EJECTOR REFRIGERATION CIRCUIT

Abstract

An ejector refrigeration circuit includes a compressor, a heating heat exchanger, a first decompressor, an exterior heat exchanger, a second decompressor, a cooling heat exchanger, a heating ejector, a heating-side gas-liquid separator, and a refrigerant circuit switch. The refrigerant circuit switch switches between a refrigerant circuit in a first dehumidifying-heating mode and a refrigerant circuit in a second dehumidifying-heating mode. A flow direction of the refrigerant through the exterior heat exchanger in the first dehumidifying-heating mode is the same as a flow direction of the refrigerant through the exterior heat exchanger in the second dehumidifying-heating mode. The flow direction of the refrigerant through the exterior heat exchanger in the first dehumidifying-heating mode is different from a flow direction of the refrigerant through the exterior heat exchanger in the heating mode.

Description

CROSS REFERENCE TO RELATED APPLICATIONS

The present application is a continuation application of International Patent Application No. PCT/JP2017/019292 filed on May 24, 2017, which designated the United States and claims the benefit of priority from Japanese Patent Application No. 2016-122859 filed on Jun. 21, 2016. The entire disclosures of all of the above applications are incorporated herein by reference.

TECHNICAL FIELD

The present disclosure relates to an ejector refrigeration circuit including an ejector.

BACKGROUND ART

Ejector refrigeration circuits may be a vapor-compression refrigeration circuit device including an ejector as a refrigerant decompressor. Such ejector refrigeration circuits may be performed with a plurality of refrigerant circuits that are set selectively.

SUMMARY OF INVENTION

In one aspect of the present disclosure, an ejector refrigeration circuit for an air conditioner may include a compressor, a heating heat exchanger, a first decompressor, an exterior heat exchanger, a second decompressor, a cooling heat exchanger, a heating ejector, a heating-side gas-liquid separator, and a refrigerant circuit switch.

The compressor compresses a refrigerant mixed with a refrigerant oil to be the refrigerant having a high pressure and discharges the refrigerant having the high pressure. The heating heat exchanger heats air to be blown into an air-conditioning object space by using the refrigerant having the high pressure as a heat source. The first decompressor is disposed downstream of the heating heat exchanger and decompresses the refrigerant. The exterior heat exchanger exchanges heat between the refrigerant flowing out of the first decompressor and an outside air. The second decompressor is disposed downstream of the heating heat exchanger and decompresses the refrigerant. The cooling heat exchanger is configured to evaporate the refrigerant flowing out of the second decompressor and to cool the air before passing through the heating heat exchanger.

The heating ejector includes a heating-side nozzle, a heating-side suction port, and a heating-side pressure increasing portion. The heating-side nozzle is disposed downstream of the heating heat exchanger, decompresses the refrigerant, and injects the refrigerant as a heating-side injected refrigerant. The heating-side suction port draws in the refrigerant as a heating-side suction refrigerant by suction force of the heating-side injected refrigerant. The heating-side pressure increasing portion pressurizes a mixed refrigerant of the heating-side injected refrigerant and the heating-side suction refrigerant. The heating-side gas-liquid separator separates the refrigerant flowing out of the heating-side pressure increasing portion into a gas refrigerant and a liquid refrigerant.

The refrigerant circuit switch is configured to set a plurality of refrigerant circuits. The refrigerant circuit switch is configured to: set a refrigerant circuit that allows the refrigerant flowing out of the heating heat exchanger to flow through in order of the first decompressor, the exterior heat exchanger, the second decompressor, the cooling heat exchanger, and the compressor in a first dehumidifying-heating mode in which the heating heat exchanger reheats the air cooled by the cooling heat exchanger; set a refrigerant circuit that allows the refrigerant flowing out of the heating heat exchanger to flow through in order of the second decompressor, the cooling heat exchanger, the first decompressor, the exterior heat exchanger, and the compressor in a second dehumidifying-heating mode in which the heating heat exchanger reheats the air cooled by the cooling heat exchanger; and set a refrigerant circuit that allows the refrigerant flowing out of the heating heat exchanger to flow into the heating-side nozzle, allows the gas refrigerant flowing out of the heating-side gas-liquid separator to be drawn into the compressor, allows the liquid refrigerant flowing out of the heating-side gas-liquid separator to flow into the exterior heat exchanger, and allows the refrigerant flowing out of the exterior heat exchanger to be drawn into the heating-side suction port in a heating mode in which the heating heat exchanger heats the air,

A flow direction of the refrigerant through the exterior heat exchanger in the first dehumidifying-heating mode is the same as a flow direction of the refrigerant through the exterior heat exchanger in the second dehumidifying-heating mode. The flow direction of the refrigerant through the exterior heat exchanger in the first dehumidifying-heating mode is different from a flow direction of the refrigerant through the exterior heat exchanger in the heating mode.

In another aspect of the present disclosure, an ejector refrigeration circuit for an air conditioner may include a compressor, a heating heat exchanger, a first decompressor, an exterior heat exchanger, a second decompressor, a cooling heat exchanger, a cooling ejector, a cooling-side gas-liquid separator, and a refrigerant circuit switch. The compressor, the heating heat exchanger, the first decompressor, the exterior heat exchanger, the second decompressor, and the cooling heat exchanger may have the same configurations as the configurations set forth above in the one aspect.

The cooling ejector includes a cooling-side nozzle, a cooling-side suction port, and a cooling-side pressure increasing portion. The cooling-side nozzle decompresses the refrigerant downstream of the heating heat exchanger and injects the refrigerant as a cooling-side injected refrigerant. The cooling-side suction port draws in the refrigerant through the cooling-side suction port as a cooling-side suction refrigerant by suction force of the cooling-side injected refrigerant. The cooling-side pressure increasing portion pressurizes a mixed refrigerant of the cooling-side injected refrigerant and the cooling-side suction refrigerant. The cooling-side gas-liquid separator separates the refrigerant flowing out of the cooling-side pressure increasing portion into a gas refrigerant and a liquid refrigerant.

The refrigerant circuit switch is configured to set a plurality of refrigerant circuits. The refrigerant circuit switch is configured to: set a refrigerant circuit that allows the refrigerant flowing out of the heating heat exchanger to flow through in order of the first decompressor, the exterior heat exchanger, the second decompressor, the cooling heat exchanger, and the compressor in a first dehumidifying-heating mode in which the heating heat exchanger reheats the air cooled by the cooling heat exchanger; set a refrigerant circuit that allows the refrigerant flowing out of the heating heat exchanger to flow through in order of the second decompressor, the cooling heat exchanger, the first decompressor, the exterior heat exchanger, and the compressor in a second dehumidifying-heating mode in which the heating heat exchanger reheats the air cooled by the cooling heat exchanger; and set a refrigerant circuit that allows the refrigerant flowing out of the exterior heat exchanger to flow into the cooling-side nozzle, allows the gas refrigerant flowing out of the cooling-side gas-liquid separator to be drawn into the compressor, allows the liquid refrigerant flowing out of the cooling-side gas-liquid separator to flow into the cooling heat exchanger, and allows the refrigerant flowing out of the cooling heat exchanger to be drawn into the cooling-side suction port in a cooling mode in which the cooling heat exchanger cools the air.

A flow direction of the refrigerant through the cooling heat exchanger in the first dehumidifying-heating mode is the same as a flow direction of the refrigerant through the cooling heat exchanger in the second dehumidifying-heating mode. The flow direction of the refrigerant through the cooling heat exchanger in the first dehumidifying-heating mode is different from a flow direction of the refrigerant through the cooling heat exchanger in the cooling mode.

BRIEF DESCRIPTION OF DRAWINGS

The above and other objects, features and advantages of the present disclosure will become more apparent from the following detailed description referring to the drawings described herein.

FIG. 1 is an overall block diagram of a vehicle air conditioner;

FIG. 2 is an overall block diagram illustrating a refrigerant circuit of an ejector refrigeration circuit in a cooling mode;

FIG. 3 is an overall block diagram illustrating a refrigerant circuit of the ejector refrigeration circuit in a first dehumidifying-heating mode;

FIG. 4 is an overall block diagram illustrating a refrigerant circuit of the ejector refrigeration circuit in a second dehumidifying-heating mode;

FIG. 5 is an overall block diagram illustrating a refrigerant circuit of the ejector refrigeration circuit in a heating mode;

FIG. 6 is an overall block diagram illustrating a refrigerant circuit of the ejector refrigeration circuit in a defrosting mode;

FIG. 7 is a block diagram illustrating an electric control unit of the vehicle air conditioner;

FIG. 8 is a Mollier chart illustrating a state of a refrigerant in the ejector refrigeration circuit in the cooling mode;

FIG. 9 is a Mollier chart illustrating a state of the refrigerant in the ejector refrigeration circuit in the first dehumidifying-heating mode;

FIG. 10 is a Mollier chart illustrating a state of the refrigerant in the ejector refrigeration circuit in the second dehumidifying-heating mode;

FIG. 11 is a Mollier chart illustrating a state of the refrigerant in the ejector refrigeration circuit in the heating mode;

FIG. 12 is a Mollier chart illustrating a state of the refrigerant in the ejector refrigeration circuit in the defrosting mode; and

FIG. 13 is an explanatory diagram for explaining a temperature adjustable range of air of the ejector refrigeration circuit.

DESCRIPTION OF EMBODIMENTS

Air conditioners may include ejector refrigeration circuits. As an example, such ejector refrigeration circuit may be performed with a plurality of refrigerant circuits that are set selectively depending on various conditions. As an example, when the ejector refrigeration circuit is performed with a refrigerant circuit in a cooling mode, the air conditioner cools air supplied into an air-conditioning object space. As an example, when the ejector refrigeration circuit is performed with a refrigerant circuit in a heating mode, the air conditioner heats the air supplied into the air-conditioning object space. As an example, when the ejector refrigeration circuit is performed with a refrigerant circuit in a low dehumidifying-heating mode, the air conditioner reheats a cooled and dehumidified air.

More specifically, in the low dehumidifying-heating mode, the ejector refrigeration circuit may set the refrigerant circuit in which an interior condenser (serving as a heating heat exchanger), an exterior heat exchanger, and an outdoor evaporator (serving as a cooling heat exchanger) are connected to each other in series along a flow direction of a refrigerant. The air is then cooled and dehumidified by an interior evaporator, and the cooled and dehumidified air is reheated in the interior condenser.

The refrigerant circuit can adjust air heating capacity (i.e., a performance heating the air) of the interior condenser by adjusting a refrigerant pressure in the exterior heat exchanger and adjusting the amount of heat radiated by the refrigerant in the exterior heat exchanger.

In the low dehumidifying-heating mode, the ejector refrigeration circuit further sets the refrigerant circuit in which the refrigerant flowing out of the exterior heat exchanger flows into a cooling-side nozzle of a cooling ejector. The refrigerant is supplied to the interior evaporator by suction force of the refrigerant injected from the cooling-side nozzle. Moreover, the refrigerant pressurized by a cooling-side diffuser is drawn into a compressor in order to improve a coefficient of performance (COP) of the cycle.

However, according to the study by the inventors of the present disclosure, such ejector refrigeration circuit in the actual operation may fail to raise the temperature of the air to a desired temperature in the low dehumidifying-heating mode. The inventors studied the reason why the temperature of the air is not increased sufficiently and found that the cause of the failure is a reduction of the refrigerant pressure in the exterior heat exchanger in order to increase the air heating capacity of the interior condenser in the low dehumidifying-heating mode.

Specifically, the reduction of the refrigerant pressure in the exterior heat exchanger causes a reduction in pressure of the refrigerant flowing into the cooling-side nozzle, so that the cooling ejector cannot perform sufficient suction. The refrigerant thus cannot be supplied to the interior evaporator, whereby the ejector refrigeration circuit cannot be operated properly. As a result, the temperature of the air cannot be raised to the desired temperature.

In other words, in the low dehumidifying-heating mode, the refrigerant pressure in the exterior heat exchanger needs to be maintained at a predetermined value or higher in order to properly operate the ejector refrigeration circuit. The temperature adjustment range of the air blown into the air-conditioning object space is thus limited in the low dehumidifying-heating mode.

Moreover, in a typical refrigeration cycle system, refrigerant oil for lubricating the compressor is mixed in the refrigerant. The failure to supply the refrigerant to the interior evaporator thus causes a failure to push the refrigerant oil flowing into the interior evaporator out to the intake side of the compressor, thereby possibly causing the refrigerant oil to stay in the interior evaporator.

When the refrigerant oil stays in the interior evaporator, the amount of the refrigerant oil supplied to the compressor is decreased. The decrease in the amount of the refrigerant oil supplied to the compressor results in deterioration in durable performance of the compressor. The decrease in the amount of the refrigerant oil supplied to the compressor further results in deterioration in heat exchange performance of the interior evaporator. As a result, a cooling capacity of the interior evaporator is reduced, i.e., a cooling performance of the interior evaporator deteriorates, when the operation is switched to the cooling mode or the like.

The present disclosure addresses the above-described issues and is unique and innovative in an ejector refrigeration circuit for an air conditioner performing a dehumidifying and heating operation.

An embodiment of the present disclosure will be described with reference to FIGS. 1 to 13. In the present embodiment, an ejector refrigeration circuit 10 according to the present disclosure is applied to a vehicle air conditioner 1 mounted on an electric vehicle as illustrated in an overall block diagram of FIG. 1. The ejector refrigeration circuit 10 in the vehicle air conditioner 1 serves a function of heating or cooling air (blown air) blown into a passenger compartment that is an air-conditioning object space. Thus, a fluid subjected to heat exchange in the ejector refrigeration circuit 10 is the air blown into the passenger compartment.

Moreover, as illustrated in FIGS. 2 to 6, the ejector refrigeration circuit 10 is configured to be switchable to a refrigerant circuit in a cooling mode (see FIG. 2), a refrigerant circuit in a first dehumidifying-heating mode (see FIG. 3), a refrigerant circuit in a second dehumidifying-heating mode (see FIG. 4), a refrigerant circuit in a heating mode (see FIG. 5), and a refrigerant circuit in a defrosting mode (see FIG. 6).

The cooling mode is an operation mode that cools the passenger compartment by cooling the air. The first dehumidifying-heating mode is an operation mode that dehumidifies and heats the passenger compartment by reheating the air that is cooled and dehumidified. The second dehumidifying-heating mode is an operation mode that dehumidifies and heats the passenger compartment by reheating the air with a heating capacity higher than that of the first dehumidifying-heating mode. The heating mode is an operation mode that heats the passenger compartment by heating the air. The defrosting mode is an operation mode that removes frost on an exterior heat exchanger 17 (described later) when frost is formed.

The arrangement of components of the ejector refrigeration circuit 10 illustrated in FIG. 1 is modified in FIGS. 2 to 6 in order to clarify the flow direction of a refrigerant in each operation mode. Specifically, a heating ejector 16, the exterior heat exchanger 17, and the like and a cooling ejector 22, an interior evaporator 21, and the like are arranged symmetrically in the drawings.

Thus, the ejector refrigeration circuit 10 illustrated in FIG. 1 is equivalent to the ejector refrigeration circuit 10 illustrated in each of FIGS. 2 to 6. FIGS. 2 to 6 also indicate the flow of the refrigerant in the corresponding operation modes by solid arrows.

The ejector refrigeration circuit 10 adopts an HFC refrigerant (specifically, R134a) as the refrigerant, and forms a subcritical refrigeration cycle in which a refrigerant pressure on the high pressure side does not exceed a critical pressure of the refrigerant. Refrigerant oil for lubricating a compressor 11 is mixed in the refrigerant. Polyalkylene glycol (PAG) oil compatible with the liquid refrigerant is adopted as the refrigerant oil. Some of the refrigerant oil circulates through the cycle with the refrigerant.

Among the components of the ejector refrigeration circuit 10, the compressor 11 is disposed under a hood of the vehicle to draw in, compress, and discharge the refrigerant in the ejector refrigeration circuit 10. The present embodiment adopts, as the compressor 11, an electric compressor in which a fixed capacity compression mechanism having a fixed discharge capacity is rotationally driven by an electric motor. The operation (speed) of the compressor 11 is controlled by a control signal output from an air conditioning controller 40 as described later.

An outlet of the compressor 11 is connected to a refrigerant inlet of an interior condenser 12. The interior condenser 12 is disposed in a casing 31 that forms an air passage in an interior air-conditioning unit 30 as described later. The interior condenser 12 is a heating heat exchanger that performs heat exchange between the refrigerant having a high pressure and discharged from the compressor 11 and the air after passage through the interior evaporator 21 (described later), and heats the air by using the refrigerant having the high pressure as a heat source. Details of the interior air-conditioning unit 30 will be described later.

A refrigerant outlet of the interior condenser 12 is connected to a first port of a first four-way valve 13a. The first four-way valve 13a is a refrigerant circuit switch that sets the refrigerant circuits of the ejector refrigeration circuit 10 together with a second four-way valve 13b and the like as described later.

The first four-way valve 13a can set a refrigerant circuit that connects the refrigerant outlet of the interior condenser 12 to a first port of a first three-way joint 14a and at the same time connects a first port of the second four-way valve 13b to a first port of a third three-way joint 14c. The first port of the first three-way joint 14a is connected to the heating ejector 16 or the exterior heat exchanger 17 to be described later. The first port of the third three-way joint 14c is connected to the cooling ejector 22 or the interior evaporator 21 as described later.

The first four-way valve 13a can also set a refrigerant circuit that connects the refrigerant outlet of the interior condenser 12 to the first port of the third three-way joint 14c and at the same time connects a second port of the second four-way valve 13b to the first port of the first three-way joint 14a. The operation of the first four-way valve 13a and the second four-way valve 13b is controlled by a control voltage output from the air conditioning controller 40.

The first three-way joint 14a is a pipe joint having three ports. The ejector refrigeration circuit 10 further includes second to fourth three-way joints 14b to 14d as described later. The basic configuration of each of the second to fourth three-way joints 14b to 14d is the similar to that of the first three-way joint 14a.

A second port of the first three-way joint 14a is connected to an inlet of a heating-side nozzle 16a of the heating ejector 16 via a first flow-control valve 15a. A third port of the first three-way joint 14a is connected to a first port of the second three-way joint 14b via a second flow-control valve 15b.

The first flow-control valve 15a is an electric variable throttle mechanism including a valve body that changes the opening degree of a refrigerant passage and an electric actuator (specifically, a stepper motor) that changes the opening degree of the valve body. The first flow-control valve 15a adjusts the flow of the refrigerant flowing into the heating-side nozzle 16a of the heating ejector 16 at least in the heating mode. The second flow-control valve 15b is a first decompressor that decompresses the refrigerant downstream of the interior condenser 12 and flowing into the exterior heat exchanger 17.

The ejector refrigeration circuit 10 further includes second to sixth flow-control valves 15b to 15f. The basic configuration of each of the second to sixth flow-control valves 15b to 15f is similar to that of the first flow-control valve 15a. The first to sixth flow-control valves 15a to 15f each have a fully open function of fully opening the valve to serve merely as a refrigerant passage while exerting almost no flow control action nor refrigerant decompression action, and a fully closed function of fully closing the valve to block the refrigerant flow path. With the fully open function and the fully closed function, the first to sixth flow-control valves 15a to 15f can switch the refrigerant circuits among the operation modes. The first to sixth flow-control valves 15a to 15f thus serves as the refrigerant circuit switch together with the first four-way valve 13a and the second four-way valve 13b. The operation of each of the first to sixth flow-control valves 15a to 15f is controlled by a control signal (control pulse) output from the air conditioning controller 40.

A second port of the second three-way joint 14b is connected to one refrigerant port of the exterior heat exchanger 17. A third port of the second three-way joint 14b is connected to a heating-side suction port 16c of the heating ejector 16 via a first switching valve 18a.

The first switching valve 18a is a solenoid valve that opens and closes the refrigerant passage connecting the second three-way joint 14b and the heating-side suction port 16c of the heating ejector 16. The ejector refrigeration circuit 10 further includes a second switching valve 18b as described later. The basic configuration of the second switching valve 18b is similar to that of the first switching valve 18a.

The first switching valve 18a and the second switching valve 18b can switch the refrigerant circuits among the operation modes described above by opening and closing the refrigerant passage. The first switching valve 18a and the second switching valve 18b thus serve as the refrigerant circuit switch together with the first four-way valve 13a and the second four-way valve 13b. The operation of each of the first switching valve 18a and the second switching valve 18b is controlled by a control voltage output from the air conditioning controller 40.

The exterior heat exchanger 17 is a heat exchanger disposed under the hood of the vehicle to perform heat exchange between the refrigerant flowing therethrough and outside air supplied from a blower fan (not shown). The exterior heat exchanger 17 serves as a radiator that causes the refrigerant having the high pressure to radiate heat at least in the cooling mode. The exterior heat exchanger 17 also serves as an evaporator that causes the refrigerant to evaporate at least in the second dehumidifying-heating mode and the heating mode.

Another refrigerant port of the exterior heat exchanger 17 is connected to a liquid-refrigerant port of a heating-side accumulator 19 via the third flow-control valve 15c.

In the present embodiment, the exterior heat exchanger 17 defines a refrigerant passage therein. The refrigerant passage has a cross-sectional area changing toward a downstream side along the flow direction of the refrigerant. More specifically, the exterior heat exchanger 17 of the present embodiment is formed of a so-called tank-and-tube heat exchanger. The cross-sectional area of the refrigerant passage defined in the exterior heat exchanger 17 is changed by adjusting the configuration of a passage through which the refrigerant flows.

Here, the passage of the tank-and-tube heat exchanger can be defined as the refrigerant passage formed of a group of tubes allowing the refrigerant in the same distribution space formed in a tank to flow in the same direction toward the same collecting space formed in the tank. Thus, the cross-sectional area of the passage (the refrigerant passage), that is, the total cross-sectional area of the tubes, can be changed by changing the number of the tubes making up the passage.

The exterior heat exchanger 17 of the present embodiment has the passage configuration in which the cross-sectional area of the refrigerant passage formed in the heat exchanger decreases gradually from the other refrigerant port toward the one refrigerant port. In the present embodiment, the other refrigerant port is connected to the liquid-refrigerant port of the heating-side accumulator 19, and the one refrigerant port is connected to the second port of the second three-way joint 14b.

Next, the heating ejector 16 serves as a decompressor that decompresses the refrigerant flowing out of the interior condenser 12 at least in the heating mode. The heating ejector 16 also serves as a refrigerant transfer unit that draws in and transfers the refrigerant flowing out of the exterior heat exchanger 17 by the suction force of the refrigerant injected at a high speed.

More specifically, the heating ejector 16 includes the heating-side nozzle 16a and a heating body 16b. The heating-side nozzle 16a is formed of a substantially cylindrical member made of metal (stainless steel in the present embodiment) having a shape that gradually converges in the flow direction of the refrigerant. The heating-side nozzle 16a decompresses the refrigerant isentropically in the refrigerant passage defined therein.

The refrigerant passage defined in the heating-side nozzle 16a includes a throat (smallest passage area) having the smallest passage cross-sectional area, and a divergent part having the refrigerant passage area that expands from the throat toward a refrigerant injection port for injecting the refrigerant. That is, the heating-side nozzle 16a is formed as a Laval nozzle.

The present embodiment adopts, as the heating-side nozzle 16a, a nozzle with which the flow rate of a heating-side injected refrigerant from the refrigerant injection port is equal to or faster than the speed of sound during normal operation of the ejector refrigeration circuit 10. The heating-side nozzle 16a may of course be formed of a convergent nozzle.

The heating body 16b is formed of a cylindrical member made of metal (an aluminum alloy in the present embodiment) to function as a fixing member that supports and fixes the heating-side nozzle 16a inside as well as form an outer shell of the heating ejector 16. More specifically, the heating-side nozzle 16a is press fitted and is fixed to be housed inside one longitudinal end of the heating body 16b. Therefore, no refrigerant leaks from the fixed part (press fitted part) between the heating-side nozzle 16a and the heating body 16b.

The heating-side suction port 16c is formed at a site corresponding to the outer peripheral side of the heating-side nozzle 16a on the outer peripheral surface of the heating body 16b. The heating-side suction port 16c passes through the outer peripheral surface of the heating body 16b to communicate with the refrigerant injection port of the heating-side nozzle 16a. The heating-side suction port 16c is a through hole that draws the refrigerant flowing out of the exterior heat exchanger 17 into the heating ejector 16 by the suction force of the heating-side injected refrigerant from the heating-side nozzle 16a.

Moreover, a suction passage and a heating-side diffuser 16d serving as a heating-side pressure increasing portion are defined in the heating body 16b. The suction passage guides the refrigerant drawn into the heating-side suction port 16c toward the refrigerant injection port of the heating-side nozzle 16a, and the heating-side diffuser 16d mixes and pressurizes the heating-side suction refrigerant and flowing into the heating ejector 16 via the suction passage and the heating-side injected refrigerant.

The heating-side diffuser 16d is disposed contiguous to the outlet of the suction passage and formed such that the area of the refrigerant passage gradually increases. The heating-side diffuser 16d thus serves a function of increasing the pressure of the mixture of the refrigerant injected and the heating-side suction refrigerant by decreasing the flow rate thereof while mixing the refrigerant injected and the heating-side suction refrigerant, or a function of converging speed energy of the mixed refrigerant into pressure energy.

The refrigerant outlet of the heating-side diffuser 16d is connected to the inlet of the heating-side accumulator 19. The heating-side accumulator 19 is a heating-side gas-liquid separator that separates the refrigerant flowing out of the heating-side diffuser 16d of the heating ejector 16 into a gas refrigerant and a liquid refrigerant. The heating-side accumulator 19 is provided with a gas-refrigerant port allowing for outflow of the gas refrigerant separated, and a liquid-refrigerant port allowing for outflow of the liquid refrigerant separated.

The present embodiment adopts an accumulator with a relatively small internal volume as the heating-side accumulator 19. The heating-side accumulator 19 thus allows the separated liquid refrigerant to flow out through the liquid-refrigerant port while storing little thereof. The separated liquid refrigerant that cannot flow out through the liquid-refrigerant port may flow out through the gas refrigerant outlet.

The gas-refrigerant port of the heating-side accumulator 19 is connected to the first port of the second four-way valve 13b serving as the refrigerant circuit switch.

The second four-way valve 13b can set a refrigerant circuit that connects the gas-refrigerant port of the heating-side accumulator 19 to a third port of the first four-way valve 13a and at the same time connects a gas-refrigerant port of a cooling-side accumulator 23 (described later) to an inlet of an intake accumulator 24.

The second four-way valve 13b can also set a refrigerant circuit that connects the gas-refrigerant port of the heating-side accumulator 19 to the inlet of the intake accumulator 24 and at the same time connects the gas-refrigerant port of the cooling-side accumulator 23 to the third port of the first four-way valve 13a.

A second port of the third three-way joint 14c to which the first four-way valve 13a is connected is connected to an inlet of a cooling-side nozzle 22a of the cooling ejector 22 via the fourth flow-control valve 15d. A third port of the third three-way joint 14c is connected to a first port of the fourth three-way joint 14d via the fifth flow-control valve 15e. The fifth flow-control valve 15e is a second decompressor that decompresses the refrigerant downstream of the interior condenser 12 and flowing into the interior evaporator 21.

A second port of the fourth three-way joint 14d is connected to one refrigerant port of the interior evaporator 21. A third port of the fourth three-way joint 14d is connected to a cooling-side refrigerant suction port 22c of the cooling ejector 22 via the second switching valve 18b.

The interior evaporator 21 is disposed upstream of the interior condenser 12 along the air flow in the casing 31 of the interior air-conditioning unit 30. The interior evaporator 21 is a cooling heat exchanger that cools the air by causing the low pressure refrigerant decompressed by the fifth flow-control valve 15e or the sixth flow-control valve 15f to exchange heat with the air, evaporate, and exert a heat absorbing action.

Another refrigerant port of the interior evaporator 21 is connected to a liquid-refrigerant port of the cooling-side accumulator 23 via the sixth flow-control valve 15f.

The present embodiment adopts, as the interior evaporator 21, a so-called tank-and-tube heat exchanger as with the exterior heat exchanger 17. The cross-sectional area of the refrigerant passage defined in the tank-and-tube heat exchanger changes toward the downstream side along the flow direction of the refrigerant.

More specifically, the interior evaporator 21 of the present embodiment has the passage configuration in which the cross-sectional area of the refrigerant passage formed in the interior evaporator 21 decreases gradually from the other refrigerant port toward the one refrigerant port. The one refrigerant port of the interior evaporator 21 is connected to the second port of the fourth three-way joint 14d. The other refrigerant port of the interior evaporator 21 is connected to the liquid-refrigerant port of the cooling-side accumulator 23.

The basic configuration of the cooling ejector 22 is similar to that of the heating ejector 16. The cooling ejector 22 thus includes the cooling-side nozzle 22a and a cooling body 22b. A cooling-side suction port 22c and a cooling-side diffuser 22d that is a cooling-side pressure increasing portion are formed in the cooling body 22b.

A refrigerant outlet of the cooling-side diffuser 22d is connected to the inlet of the cooling-side accumulator 23. The cooling-side accumulator 23 is a cooling-side gas-liquid separator that separates the refrigerant flowing out of the cooling-side diffuser 22d of the cooling ejector 22 into a gas refrigerant and a liquid refrigerant. The cooling-side accumulator 23 is provided with a gas refrigerant outlet allowing for outflow of the gas refrigerant separated and a liquid refrigerant outlet allowing for outflow of the liquid refrigerant separated.

The present embodiment adopts an accumulator with a relatively small internal volume as the cooling-side accumulator 23, as with the heating-side accumulator 19. The cooling-side accumulator 23 thus allows the separated liquid refrigerant to flow out through the liquid-refrigerant port while storing little thereof. The separated liquid refrigerant that cannot flow out through the liquid-refrigerant port may flow out through the gas refrigerant outlet.

The gas-refrigerant port of the cooling-side accumulator 23 is connected to a third port of the second four-way valve 13b serving as the refrigerant circuit switch. The intake accumulator 24 is a gas-liquid separator that separates the refrigerant drawn into the compressor 11 into a gas refrigerant and a liquid refrigerant. The intake accumulator 24 causes the separated gas refrigerant to flow out toward an inlet of the compressor 11 and at the same time accumulates surplus refrigerant in the cycle.

Next, the interior air-conditioning unit 30 will be described. The interior air-conditioning unit 30 blows the air subjected to temperature control by the ejector refrigeration circuit 10 into the passenger compartment, and is disposed on the inner side relative to an instrument panel (that is, inside the passenger compartment) which is at the foremost part of the passenger compartment. The interior air-conditioning unit 30 houses a blower 32, the interior evaporator 21, the interior condenser 12, an air mix door 34, and the like in the casing 31 forming the outer shell of the interior air-conditioning unit 30.

The casing 31 forms the air passage for the air blown into the passenger compartment, and is thus made of resin (such as polypropylene) having some elasticity and excellent strength. An inside/outside air switch 33 as an inside/outside air switch that switchably introduces inside air (air in the passenger compartment) and outside air (air outside the passenger compartment) into the casing 31 is disposed on the most upstream side of the air flow in the casing 31.

The inside/outside air switch 33 uses an inside/outside air switching door to continuously adjust the area of opening of an inside-air introduction port that introduces the inside air into the casing 31 and an outside-air introduction port that introduces the outside air into the casing 31, thereby continuously changing a ratio of the air volume of the inside air to the air volume of the outside air. The inside/outside air switching door is driven by an electric actuator for the inside/outside air switching door, and the operation of the electric actuator is controlled by a control signal output from the air conditioning controller 40.

The blower 32 as a blower unit is disposed downstream of the inside/outside air switch 33 along the air flow, and blows the air drawn in via the inside/outside air switch 33 toward the passenger compartment. The blower 32 is an electric blower that drives a multi-blade centrifugal fan (sirocco fan) with an electric motor, where the speed (volume of air supplied) is controlled by a control voltage output from the air conditioning controller 40.

The interior evaporator 21 and the interior condenser 12 are disposed in this order downstream of the blower 32 along the air flow. That is, the interior evaporator 21 is disposed upstream of the interior condenser 12 along the air flow. The air mix door 34 adjusting a ratio of the air allowed to pass through the interior condenser 12 out of the air passing through the interior evaporator 21 is disposed downstream of the interior evaporator 21 and upstream of the interior condenser 12 along the air flow.

A mixing space 35 is provided downstream of the interior condenser 12 along the air flow and allows for mixing of the air heated by heat exchange with the refrigerant in the interior condenser 12 and the air bypassing the interior condenser 12 and not heated. An opening is provided at the most downstream part of the casing 31 along the air flow to allow the air (conditioned air) mixed in the mixing space 35 to be blown into the passenger compartment that is the air-conditioning object space.

Specifically, a face opening, a foot opening, and a defroster opening (none of which is shown) are provided as the opening. The face opening is the opening for blowing the conditioned air toward an upper body of a passenger in the passenger compartment. The foot opening is the opening for blowing the conditioned air toward feet of the passenger. The defroster opening is the opening for blowing the conditioned air toward an inner surface of a windshield of the vehicle.

The face opening, the foot opening, and the defroster opening are connected to a face vent, a foot vent, and a defroster vent (none of which is shown) provided in the passenger compartment via ducts forming the air passage, respectively.

Thus, the temperature of the conditioned air mixed in the mixing space is adjusted by the air mix door 34 adjusting the ratio of the volume of air passing through the interior condenser 12 and the volume of air bypassing the interior condenser 12. As a result, the temperature of the air (conditioned air) blown into the passenger compartment through each vent is adjusted.

In other words, the air mix door 34 serves as a temperature adjustment unit that adjusts the temperature of the conditioned air blown into the passenger compartment. The air mix door 34 is driven by an electric actuator for driving the air mix door, and the operation of the electric actuator is controlled by a control signal output from the air conditioning controller 40.

A face door for adjusting the area of opening of the face opening, a foot door for adjusting the area of opening of the foot opening, and a defroster door for adjusting the area of opening of the defroster opening (none of which is shown) are disposed upstream of the face opening, the foot opening, and the defroster opening along the air flow, respectively.

The face door, the foot door, and the defroster door make up an opening mode switch that switches an opening mode, and are connected to an electric actuator for driving the door corresponding to a vent mode via a link mechanism or the like to be turned while interlocked therewith. The operation of the electric actuator is also controlled by a control signal output from the air conditioning controller 40.

Vent modes switched by a vent mode switch specifically include a face mode, a bi-level mode, a foot mode, and the like.

The face mode is the vent mode in which the air is blown out through the face vent toward the upper body of a passenger in the passenger compartment by fully opening the face vent. The bi-level mode is the vent mode in which the air is blown out toward the upper body and feet of the passenger in the passenger compartment by opening both the face vent and the foot vent. The foot mode is the vent mode in which the air is blown out mainly through the foot vent by fully opening the foot vent and slightly opening the defroster vent.

When the passenger manually operates a vent mode selector switch provided on an operation panel 50, the blowing mode can also be switched to a defroster mode in which the air is blown out through the defroster vent toward the inner surface of the vehicle windshield by fully opening the defroster vent.

Next, the electric control unit (ECU) of the present embodiment will be described. The air conditioning controller 40 is formed of a well-known microcomputer including a CPU, a ROM, a RAM, and the like and a peripheral circuit thereof. The air conditioning controller 40 performs various calculations and processing on the basis of a control program stored in the ROM, thereby controlling the operation of various controlled devices connected on the output side. The various controlled devices include, for example, the compressor 11, the first four-way valve 13a, the second four-way valve 13b, the flow-control valves 15a to 15f, the first switching valve 18a, the second switching valve 18b, the blower 32, and the like.

Moreover, as illustrated in the block diagram of FIG. 7, an inside-air temperature sensor 41, an outside-air temperature sensor 42, a solar sensor 43, an exterior-heat-exchanger temperature sensor 44, a discharge temperature sensor 45, an interior-evaporator temperature sensor 46, a conditioned-air temperature sensor 47, and the like are connected on the input side of the air conditioning controller 40. The air conditioning controller 40 receives input of signals detected by the group of sensors.

The inside-air temperature sensor 41 is an inside-air temperature detector that detects a temperature inside the passenger compartment (an inside-air temperature) Tr. The outside-air temperature sensor 42 is an outside-air temperature detector that detects a temperature outside the passenger compartment (an outside-air temperature) Tam. The solar sensor 43 is a solar radiation detector that detects an amount of solar radiation As entering the passenger compartment. The exterior-heat-exchanger temperature sensor 44 is an exterior-heat-exchanger temperature detector that detects a temperature of the refrigerant in the exterior heat exchanger (an exterior-heat-exchanger temperature) Tout. The discharge temperature sensor 45 is a discharge temperature detector that detects a discharge refrigerant temperature Td of the compressor 11. The interior-evaporator temperature sensor 46 is an evaporator temperature detector that detects a refrigerant evaporating temperature of the interior evaporator 21 (an interior evaporator temperature) Tefin. The conditioned-air temperature sensor 47 is a conditioned air temperature detector that detects an air temperature TAV of the air blown into the passenger compartment from the mixing space.

Moreover, as illustrated in FIG. 7, the operation panel 50 disposed near the instrument panel in the front part of the passenger compartment is connected on the input side of the air conditioning controller 40, which receives input of operation signals from various operation switches provided on the operation panel 50. The various operation switches provided on the operation panel 50 include an auto switch, a cooling switch (an A/C switch), an air volume setting switch, a temperature setting switch, the blowing mode selector switch, and the like.

The auto switch is an input unit that sets or cancels the automatic control operation of the vehicle air conditioner 1. The cooling switch (A/C switch) is an input unit that makes a request to cool the passenger compartment. The air volume setting switch is an input unit that manually sets the air volume of the blower 32. The temperature setting switch is an input unit that manually sets a target temperature Tset in the passenger compartment. The blowing mode selector switch is an input unit that manually sets the blowing mode.

The air conditioning controller 40 of the present embodiment is formed by the integration of controllers for controlling the various controlled devices connected on the output side of the air conditioning controller 40. A configuration (hardware and software) for controlling the operation of each of the various controlled devices implements the controller for controlling the operation of each of the various controlled devices.

For example, a configuration for controlling the refrigerant discharge capacity (speed) of the compressor 11 implements a discharge capacity controller in the air conditioning controller 40. Moreover, a configuration for controlling the operation of the refrigerant circuit switch such as the first switching valve 18a and the second switching valve 18b implements a refrigerant circuit controller.

Next, the operation of the present embodiment having the above configuration will be described. As described above, the ejector refrigeration circuit 10 of the present embodiment can switch the operation mode among the cooling mode, the first dehumidifying-heating mode, the second dehumidifying-heating mode, the heating mode, and the defrosting mode.

The operation mode is switched by execution of an air conditioning control program stored in advance in a storage circuit of the air conditioning controller 40. The air conditioning control program is executed when the auto switch on the operation panel 50 is turned on.

More specifically, the main routine of the air conditioning control program reads the signals detected by the group of sensors for air conditioning control and the operation signals from the various air conditioning operation switches. On the basis of the values of the signals detected and operation signals being read, a target supply-air temperature TAO that is a target temperature of the air flowing into the passenger compartment is calculated according to formula F1 below.

TAO=Kset×Tset−Kr×Tr−Kam×Tam−Ks×As+C  (F1)

In the formula, Tset is a set temperature in the passenger compartment set by the temperature setting switch, Tr is the temperature inside the passenger compartment (inside-air temperature) detected by the inside air sensor, Tam is the outside-air temperature detected by the outside air sensor, and As is the amount of solar radiation detected by the solar sensor. Moreover, Kset, Kr, Kam, and Ks are control gains, and C is a correction constant.

The operation in the cooling mode is executed when the cooling switch on the operation panel 50 is turned on and the target supply-air temperature TAO is lower than a predetermined reference cooling temperature α.

The operation in the first dehumidifying-heating mode is executed when the target supply-air temperature TAO is equal to or higher than the reference cooling temperature α and the outside-air temperature Tam is higher than a predetermined reference dehumidifying/heating temperature 13 while the cooling switch is turned on. The operation in the second dehumidifying-heating mode is executed when the target supply-air temperature TAO is equal to or higher than the reference cooling temperature α and the outside-air temperature Tam is equal to or lower than the reference dehumidifying/heating temperature 13 while the cooling switch is turned on.

The operation in the heating mode is executed when the cooling switch is not turned on. The defrosting operation to remove frost is executed when frost is formed in the exterior heat exchanger 17 during execution of the heating mode or the like.

The vehicle air conditioner 1 according to the present embodiment thus executes the operation in the cooling mode when the outside-air temperature is relatively high mainly as in summer. The vehicle air conditioner 1 executes the operation in the first or second dehumidifying-heating mode mainly in early spring or early winter. The vehicle air conditioner 1 executes the operation in the heating mode when the outside-air temperature is relatively low mainly as in winter.

The operation in each operation mode will be described below.

(a) Cooling Mode

In the cooling mode, the air conditioning controller 40 controls the operation of the first four-way valve 13a to set the refrigerant circuit in which the refrigerant outlet of the interior condenser 12 is connected to the first three-way joint 14a and at the same time the second four-way valve 13b is connected to the third three-way joint 14c. The air conditioning controller 40 also controls the operation of the second four-way valve 13b to set the refrigerant circuit in which the gas-refrigerant port of the heating-side accumulator 19 is connected to the first four-way valve 13a and at the same time the gas-refrigerant port of the cooling-side accumulator 23 is connected to the inlet of the intake accumulator 24.

The air conditioning controller 40 further controls the first flow-control valve 15a to be fully closed, the second flow-control valve 15b to be fully open, the third flow-control valve 15c to be fully open, the fourth flow-control valve 15d to be throttled such that the refrigerant decompression action is exerted, the fifth flow-control valve 15e to be fully closed, and the sixth flow-control valve 15f to be throttled. The air conditioning controller 40 also closes the first switching valve 18a and opens the second switching valve 18b.

Thus, as indicated by solid arrows in FIG. 2, the cooling mode forms the ejector refrigeration circuit in which the refrigerant is circulated in the order of the compressor 11, the interior condenser 12, (the second flow-control valve 15b) the exterior heat exchanger 17, (the third flow-control valve 15c) the heating-side accumulator 19, the fourth flow-control valve 15d, the cooling ejector 22, the cooling-side accumulator 23, the intake accumulator 24, and the compressor 11, and in the order of the cooling-side accumulator 23, the sixth flow-control valve 15f, the interior evaporator 21, and the cooling-side suction port 22c of the cooling ejector 22.

The air conditioning controller 40 determines the operating state of each of the various controlled devices (a control signal output to each of the various controlled devices) on the basis of the target supply-air temperature TAO, the signals detected by the group of sensors, and the like in the refrigerant circuit above.

For example, the refrigerant discharge capacity of the compressor 11, that is, the control signal output to the electric motor of the compressor 11, is determined as follows. First, on the basis of the target supply-air temperature TAO, a target evaporator blowing air temperature TEO of the interior evaporator 21 is determined with reference to a control map stored in advance in the air conditioning controller 40. The target evaporator blowing air temperature TEO is determined to be equal to or higher than a reference frost formation preventing temperature (such as 1° C.) which is determined to be able to prevent frost formation in the interior evaporator 21.

Then on the basis of a deviation between the target evaporator blowing air temperature TEO and the interior evaporator temperature Tefin detected by the interior-evaporator temperature sensor 46, the control signal output to the electric motor of the compressor 11 is determined using feedback control such that the interior evaporator temperature Tefin approaches the target evaporator blowing air temperature TEO.

The throttle opening degree of the fourth flow-control valve 15d, that is, the control signal (control pulse) output to the fourth flow-control valve 15d is determined with reference to the control map stored in advance in the air conditioning controller 40 on the basis of the target supply-air temperature TAO. Specifically, the control signal is determined such that the COP of the ejector refrigeration circuit 10 approaches the local maximum.

The throttle opening degree of the sixth flow-control valve 15f, that is, the control signal (control pulse) output to the sixth flow-control valve 15f is set to a reference opening degree for cooling that is stored in advance in the air conditioning controller 40.

The control signal output to the electric actuator for driving the air mix door 34 is determined such that the air mix door 34 blocks the air passage on the side of the interior condenser 12 to allow the entire flow of the air after passage through the interior evaporator 21 to flow around the interior condenser 12.

The control signals and the like determined as described above are output to the various controlled devices. After that, a control routine is repeated every predetermined control cycle until a request is made to stop the operation of the vehicle air conditioner 1, the control routine including reading of the signals detected and the operation signals, calculation of the target supply-air temperature TAO, determination of the operating state of the various controlled devices, and output of the control voltage and control signals. The control routine is repeated similarly in another operation mode as well.

Accordingly, the state of the refrigerant in the ejector refrigeration circuit 10 changes as illustrated in a Mollier chart of FIG. 8 in the cooling mode.

Specifically, the refrigerant having the high pressure and discharged from the compressor 11 flows into the interior condenser 12 (point a8 in FIG. 8). At this time, the air passage on the side of the interior condenser 12 is blocked by the air mix door 34 so that the refrigerant flowing into the interior condenser 12 flows out of the interior condenser 12 with almost no heat exchange with the air.

The refrigerant flowing out of the interior condenser 12 flows into the one refrigerant port of the exterior heat exchanger 17 via the first four-way valve 13a, the second flow-control valve 15b that is fully open, and the like. The refrigerant flowing into the exterior heat exchanger 17 radiates heat to the outside air supplied from the blower fan in the exterior heat exchanger 17 and is condensed (from point a8 to point e8 in FIG. 8).

The refrigerant flowing out of the other refrigerant port of the exterior heat exchanger 17 flows into the heating-side accumulator 19 via the third flow-control valve 15c that is fully open, and is separated into the gas refrigerant and the liquid refrigerant. The liquid refrigerant separated by the heating-side accumulator 19 flows into the fourth flow-control valve 15d via the second four-way valve 13b, the first four-way valve 13a, and the like and is decompressed (from point e8 to point h8 in FIG. 8).

The refrigerant decompressed by the fourth flow-control valve 15d flows into the cooling-side nozzle 22a of the cooling ejector 22. The refrigerant flowing into the cooling-side nozzle 22a is isentropically decompressed and injected (from point h8 to point i8 in FIG. 8). The refrigerant flowing out of the one refrigerant port of the interior evaporator 21 is drawn in on the cooling side through the cooling-side suction port 22c of the cooling ejector 22 by the suction force of the refrigerant injected from the cooling-side nozzle 22a.

The cooling-side injected refrigerant from the cooling-side nozzle 22a and the cooling-side suction refrigerant through the cooling-side suction port 22c of the cooling ejector 22 flow into the cooling-side diffuser 22d (from point i8 to point j8 and from point p8 to point j8 in FIG. 8).

The increase in the area of the refrigerant passage in the cooling-side diffuser 22d allows the speed energy of the refrigerant to be converted into the pressure energy. As a result, the pressure of the mixture of the refrigerant injected and the cooling-side suction refrigerant is increased (from point j8 to point k8 in FIG. 8). The refrigerant flowing out of the cooling-side diffuser 22d flows into the cooling-side accumulator 23 and is separated into the gas refrigerant and the liquid refrigerant.

The liquid refrigerant separated by the cooling-side accumulator 23 (point m8 in FIG. 8) flows into the sixth flow-control valve 15f in the throttled state, and is decompressed (from point m8 to point o8 in FIG. 8). The refrigerant decompressed by the sixth flow-control valve 15f flows into the interior evaporator 21 through the other refrigerant port thereof, absorbs heat from the air supplied by the blower 32, and evaporates (from point o8 to point p8 in FIG. 8). The air is cooled as a result.

The gas refrigerant separated by the cooling-side accumulator 23 (point n8 in FIG. 8) is drawn into the compressor 11 via the second four-way valve 13b, the intake accumulator 24, and the like and is compressed again (from point n8 to point a8 in FIG. 8).

The cooling mode can thus cool the passenger compartment by blowing the air cooled by the interior evaporator 21 into the passenger compartment without reheating it in the interior condenser 12.

Moreover, in the cooling mode, the refrigerant pressurized by the cooling-side diffuser 22d of the cooling ejector 22 is drawn into the compressor 11. Specifically, the refrigerant circuit switch (i.e., the switching valves 13a, 13b, 18a, 18b) sets the refrigerant circuit in which the gas refrigerant flowing out of the cooling-side gas-liquid separator (i.e., the cooling-side accumulator 23) is drawn into the compressor 11, whereby the refrigerant pressurized by the cooling-side pressure increasing portion (i.e., the cooling-side diffuser 22d) can be drawn into the compressor 11. Therefore, the power consumption of the compressor 11 can be reduced to be able to improve the coefficient of performance COP of the cycle as compared with a typical refrigeration cycle system in which the refrigerant evaporating pressure of the heat exchanger (the interior evaporator 21 in the cooling mode) functioning as the evaporator is equal to the pressure of the refrigerant drawn into the compressor 11.

(b) First Dehumidifying-Heating Mode

In the first dehumidifying-heating mode, the air conditioning controller 40 controls the operation of the first four-way valve 13a to set the refrigerant circuit in which the refrigerant outlet of the interior condenser 12 is connected to the first three-way joint 14a and at the same time the second four-way valve 13b is connected to the third three-way joint 14c. The air conditioning controller 40 also controls the operation of the second four-way valve 13b to set the refrigerant circuit in which the gas-refrigerant port of the heating-side accumulator 19 is connected to the first four-way valve 13a and at the same time the gas-refrigerant port of the cooling-side accumulator 23 is connected to the inlet of the intake accumulator 24.

The air conditioning controller 40 further controls the first flow-control valve 15a to be fully closed, the second flow-control valve 15b to be throttled, the third flow-control valve 15c to be fully open, the fourth flow-control valve 15d to be fully closed, the fifth flow-control valve 15e to be throttled, and the sixth flow-control valve 15f to be fully open. The air conditioning controller 40 also closes the first switching valve 18a and closes the second switching valve 18b.

Thus, as indicated by solid arrows in FIG. 3, the first dehumidifying-heating mode forms the refrigeration cycle in which the refrigerant is circulated in the order of the compressor 11, the interior condenser 12, the second flow-control valve 15b, the exterior heat exchanger 17, (the third flow-control valve 15c) the heating-side accumulator 19, the fifth flow-control valve 15e, the interior evaporator 21, (the sixth flow-control valve 15f) the cooling-side accumulator 23, the intake accumulator 24, and the compressor 11.

Accordingly, in the first dehumidifying-heating mode, the interior condenser 12, the exterior heat exchanger 17, and the interior evaporator 21 are connected in series in this order along the refrigerant flow.

The air conditioning controller 40 determines the operating state of each of the various controlled devices (a control signal output to each of the various controlled devices) on the basis of the target supply-air temperature TAO, the signals detected by the group of sensors, and the like in the refrigerant circuit above.

For example, the throttle opening degree of the second flow-control valve 15b, that is, the control signal (control pulse) output to the second flow-control valve 15b is determined with reference to the control map stored in advance in the air conditioning controller 40 on the basis of the target supply-air temperature TAO. Specifically, the control signal is determined such that the throttle opening degree is reduced with an increase in the target supply-air temperature TAO. In other words, the control signal is determined such that the throttle opening degree is reduced with an increase in the heating capacity required for the cycle.

The throttle opening degree of the fifth flow-control valve 15e, that is, the control signal (control pulse) output to the fifth flow-control valve 15e, is determined with reference to the control map stored in advance in the air conditioning controller 40 on the basis of the target supply-air temperature TAO. Specifically, the control signal is determined such that the COP of the ejector refrigeration circuit 10 approaches the local maximum.

The throttle opening degree of the fifth flow-control valve 15e is thus increased as the throttle opening degree of the second flow-control valve 15b is reduced. In other words, the throttle opening degree of the fifth flow-control valve 15e is determined to be increased as the heating capacity required for the cycle is increased.

The opening degree of the air mix door 34, that is, the control signal output to the electric actuator for driving the air mix door 34, is determined such that the air temperature TAV detected by the conditioned-air temperature sensor 47 approaches the target supply-air temperature TAO. The operating state of each of the other controlled devices is determined in the manner similar to that for the cooling mode.

Accordingly, the state of the refrigerant in the ejector refrigeration circuit changes as illustrated in a Mollier chart of FIG. 9 in the first dehumidifying-heating mode. In the Mollier chart of FIG. 9, the state of the refrigerant at a site equivalent in the cycle configuration to that in the Mollier chart of FIG. 8 described in the cooling mode is denoted by the same reference character (alphabetic letter) as that in FIG. 8, and only the suffix (number) assigned to the site is changed. The similar applies to other Mollier charts described below.

Specifically, in the first dehumidifying-heating mode, the air mix door 34 opens the air passage on the side of the interior condenser 12 so that the refrigerant having the high pressure and discharged from the compressor 11 flows into the interior condenser 12 (point a9 in FIG. 9), exchanges heat with some of the air cooled and dehumidified by the interior evaporator 21, and radiates heat (from point a9 to point b9 in FIG. 9). Some of the air is heated as a result.

The refrigerant flowing out of the interior condenser 12 flows into the second flow-control valve 15b via the first four-way valve 13a and the like, and is decompressed (from point b9 to point c9 in FIG. 9). The refrigerant decompressed by the second flow-control valve 15b flows into the one refrigerant port of the exterior heat exchanger 17.

Here, when the exterior-heat-exchanger temperature Tout is higher than the outside-air temperature Tam, as illustrated in FIG. 9, the refrigerant flowing into the exterior heat exchanger 17 radiates heat to the outside air supplied by the blower fan in the exterior heat exchanger 17 (from point c9 to point e9 in FIG. 9). On the other hand, when the exterior-heat-exchanger temperature Tout is lower than the outside-air temperature Tam, the refrigerant flowing into the exterior heat exchanger 17 absorbs heat from the outside air supplied by the blower fan in the exterior heat exchanger 17.

The refrigerant flowing out of the other refrigerant port of the exterior heat exchanger 17 flows into the fifth flow-control valve 15e via the heating-side accumulator 19, the second four-way valve 13b, the first four-way valve 13a, and the like and is decompressed (from point e9 to point p9 in FIG. 9).

The refrigerant decompressed by the fifth flow-control valve 15e flows into the interior evaporator 21 through the one refrigerant port thereof, exchanges heat with the air supplied by the blower 32, and evaporates (from point p9 to point n9 in FIG. 9). The air is cooled as a result. The refrigerant flowing out of the other refrigerant port of the interior evaporator 21 is drawn into the compressor 11 via the cooling-side accumulator 23, the second four-way valve 13b, the intake accumulator 24, and the like and is compressed again (from point n9 to point a9 in FIG. 9).

The first dehumidifying-heating mode can thus dehumidify and heat the passenger compartment by reheating the air cooled and dehumidified by the interior evaporator 21 in the interior condenser 12 and blowing it into the passenger compartment.

The first dehumidifying-heating mode throttles the first flow-control valve 15a so that the temperature of the refrigerant flowing into the exterior heat exchanger 17 is lower than that in the cooling mode. As a result, the difference between the temperature of the refrigerant in the exterior heat exchanger 17 and the outside-air temperature can be smaller than that in the cooling mode, whereby the amount of heat radiated by the refrigerant in the exterior heat exchanger 17 can be smaller than that in the cooling mode.

Therefore, as compared to the case where the operation of the air mix door 34 is simply controlled such that the air temperature TAV approaches the target supply-air temperature TAO in the cooling mode, the air heating capacity of the interior condenser 12 can be improved by increasing the refrigerant pressure in the interior condenser 12 without increasing the flow of the refrigerant circulating in the cycle.

(c) Second Dehumidifying-Heating Mode

In the second dehumidifying-heating mode, the air conditioning controller 40 controls the operation of the first four-way valve 13a to set the refrigerant circuit in which the refrigerant outlet of the interior condenser 12 is connected to the third three-way joint 14c and at the same time the second four-way valve 13b is connected to the first three-way joint 14a. The air conditioning controller 40 also controls the operation of the second four-way valve 13b to set the refrigerant circuit in which the gas-refrigerant port of the heating-side accumulator 19 is connected to the inlet of the intake accumulator 24 and at the same time the gas-refrigerant port of the cooling-side accumulator 23 is connected to the first four-way valve 13a.

The air conditioning controller 40 further controls the first flow-control valve 15a to be fully closed, the second flow-control valve 15b to be throttled, the third flow-control valve 15c to be fully open, the fourth flow-control valve 15d to be fully closed, the fifth flow-control valve 15e to be throttled, and the sixth flow-control valve 15f to be fully open. The air conditioning controller 40 also closes the first switching valve 18a and closes the second switching valve 18b.

Thus, as indicated by solid arrows in FIG. 4, the second dehumidifying-heating mode forms the refrigeration cycle in which the refrigerant is circulated in the order of the compressor 11, the interior condenser 12, the fifth flow-control valve 15e, the interior evaporator 21, (the sixth flow-control valve 15f) the cooling-side accumulator 23, the second flow-control valve 15b, the exterior heat exchanger 17, (the third flow-control valve 15c) the heating-side accumulator 19, the intake accumulator 24, and the compressor 11.

Accordingly, in the second dehumidifying-heating mode, the interior condenser 12, the interior evaporator 21, and the exterior heat exchanger 17 are connected in series in this order along the refrigerant flow.

The air conditioning controller 40 determines the operating state of each of the various controlled devices (a control signal output to each of the various controlled devices) on the basis of the target supply-air temperature TAO, the signals detected by the group of sensors, and the like in the refrigerant circuit above.

For example, the throttle opening degree of the fifth flow-control valve 15e, that is, the control signal (control pulse) output to the fifth flow-control valve 15e is determined with reference to the control map stored in advance in the air conditioning controller 40 on the basis of the target supply-air temperature TAO. Specifically, the control signal is determined such that the throttle opening degree is reduced with an increase in the target supply-air temperature TAO. In other words, the control signal is determined such that the throttle opening degree is reduced with an increase in the heating capacity required for the cycle.

The throttle opening degree of the second flow-control valve 15b, that is, the control signal (control pulse) output to the second flow-control valve 15b is determined with reference to the control map stored in advance in the air conditioning controller 40 on the basis of the target supply-air temperature TAO. Specifically, the control signal is determined such that the COP of the ejector refrigeration circuit 10 approaches the local maximum.

The throttle opening degree of the second flow-control valve 15b is thus increased as the throttle opening degree of the fifth flow-control valve 15e is reduced. In other words, the control signal is determined such that the throttle opening degree is increased as the heating capacity required for the cycle is increased.

The opening degree of the air mix door 34, that is, the control signal output to the electric actuator for driving the air mix door 34, is determined such that the air temperature TAV detected by the conditioned-air temperature sensor 47 approaches the target supply-air temperature TAO. The operating state of each of the other controlled devices is determined in the manner similar to that for the cooling mode.

Accordingly, the state of the refrigerant in the ejector refrigeration circuit 10 changes as illustrated in a Mollier chart of FIG. 10 in the second dehumidifying-heating mode.

Specifically, in the second dehumidifying-heating mode, the air mix door 34 opens the air passage on the side of the interior condenser 12 so that the refrigerant having the high pressure and discharged from the compressor 11 flows into the interior condenser 12 (point a10 in FIG. 10), exchanges heat with some of the air cooled and dehumidified by the interior evaporator 21, and radiates heat (from point a10 to point b10 in FIG. 10). Some of the air is heated as a result.

The refrigerant flowing out of the interior condenser 12 flows into the fifth flow-control valve 15e via the first four-way valve 13a and the like, and is decompressed (from point b10 to point p10 in FIG. 10). The refrigerant decompressed by the fifth flow-control valve 15e flows into the one refrigerant port of the interior evaporator 21. The refrigerant flowing into the interior evaporator 21 exchanges heat with the air supplied from the blower 32 and evaporates (from point p10 to point n10 in FIG. 10). The air is cooled as a result.

The refrigerant flowing out of the other refrigerant port of the interior evaporator 21 flows into the second flow-control valve 15b via the cooling-side accumulator 23, the second four-way valve 13b, the first four-way valve 13a, and the like and is decompressed (from point n10 to point c10 in FIG. 10).

The refrigerant decompressed by the second flow-control valve 15b flows into the one refrigerant port of the exterior heat exchanger 17, and absorbs heat from the outside air supplied by the blower fan (from point c10 to point f10 in FIG. 10). The refrigerant flowing out of the other refrigerant port of the exterior heat exchanger 17 is drawn into the compressor 11 via the heating-side accumulator 19, the second four-way valve 13b, the intake accumulator 24, and the like and is compressed again (from point f10 to point a10 in FIG. 10).

The second dehumidifying-heating mode can thus dehumidify and heat the passenger compartment by reheating the air cooled and dehumidified by the interior evaporator 21 in the interior condenser 12 and blowing it into the passenger compartment.

In the second dehumidifying-heating mode, the exterior heat exchanger 17 serves as an evaporator with the refrigerant evaporating pressure of the exterior heat exchanger 17 lower than the refrigerant evaporating pressure of the interior evaporator 21. As a result, the amount of heat radiated by the refrigerant in the interior condenser 12 can be higher than that in the first dehumidifying-heating mode.

The refrigerant pressure in the interior condenser 12 can thus be increased without increasing the flow of the refrigerant circulating in the cycle relative to that in the first dehumidifying-heating mode. As a result, the air heating capacity of the interior condenser 12 is improved so that the air temperature can be raised to a higher temperature range than in the first dehumidifying-heating mode.

Moreover, as is apparent from the above description, the flow direction of the refrigerant through the exterior heat exchanger 17 in the first dehumidifying-heating mode is the same as the flow direction of the refrigerant through the exterior heat exchanger 17 in the second dehumidifying-heating mode. That is, the refrigerant flows from the one refrigerant port to the other refrigerant port of the exterior heat exchanger 17 in the first and second dehumidifying-heating modes.

The flow direction of the refrigerant through the interior evaporator 21 in the first dehumidifying-heating mode is the same as the flow direction of the refrigerant through the interior evaporator 21 in the second dehumidifying-heating mode. That is, the refrigerant flows from the one refrigerant port to the other refrigerant port of the interior evaporator 21 in the first and second dehumidifying-heating modes.

The flow direction of the refrigerant through the interior evaporator 21 in the first and second dehumidifying-heating modes is different from the flow direction of the refrigerant through the interior evaporator 21 in the cooling mode. That is, the refrigerant flows from the other refrigerant port to the one refrigerant port of the interior evaporator 21 in the cooling mode.

(d) Heating Mode

In the heating mode, the air conditioning controller 40 controls the operation of the first four-way valve 13a to set the refrigerant circuit in which the refrigerant outlet of the interior condenser 12 is connected to the first three-way joint 14a and at the same time the second four-way valve 13b is connected to the third three-way joint 14c. The air conditioning controller 40 also controls the operation of the second four-way valve 13b to set the refrigerant circuit in which the gas-refrigerant port of the heating-side accumulator 19 is connected to the inlet of the intake accumulator 24 and at the same time the gas-refrigerant port of the cooling-side accumulator 23 is connected to the first four-way valve 13a.

The air conditioning controller 40 further controls the first flow-control valve 15a to be throttled, the second flow-control valve 15b to be fully closed, the third flow-control valve 15c to be throttled, and the first switching valve 18a to be open.

Thus, as indicated by solid arrows in FIG. 5, the heating mode forms the ejector refrigeration circuit in which the refrigerant is circulated in the order of the compressor 11, the interior condenser 12, the first flow-control valve 15a, the heating ejector 16, the heating-side accumulator 19, the intake accumulator 24, and the compressor 11, and in the order of the heating-side accumulator 19, the third flow-control valve 15c, the exterior heat exchanger 17, and the heating-side suction port 16c of the heating ejector 16.

The air conditioning controller 40 determines the operating state of each of the various controlled devices (a control signal output to each of the various controlled devices) on the basis of the target supply-air temperature TAO, the signals detected by the group of sensors, and the like in the refrigerant circuit above.

For example, the refrigerant discharge capacity of the compressor 11, that is, the control signal output to the electric motor of the compressor 11, is determined as follows. First, on the basis of the target supply-air temperature TAO, a target condenser temperature TCO of the interior condenser 12 is determined with reference to the control map stored in advance in the air conditioning controller 40.

Then on the basis of a deviation between the target condenser temperature TCO and the discharge refrigerant temperature Td detected by the discharge temperature sensor 45, the control signal output to the electric motor of the compressor 11 is determined using feedback control such that the discharge refrigerant temperature Td approaches the target condenser temperature TCO.

The throttle opening degree of the first flow-control valve 15a, that is, the control signal (control pulse) output to the first flow-control valve 15a is determined with reference to the control map stored in advance in the air conditioning controller 40 on the basis of the refrigerant discharge capacity of the compressor 11 such as the control signal output to the electric motor of the compressor 11.

The control map determines the throttle opening degree of the first flow-control valve 15a such that dryness x of the refrigerant flowing into the heating-side nozzle 16a is 0.5 or higher and 0.8 or lower. The range of the dryness x is a value obtained by prior experiment as a value at which the air heating capacity of the interior condenser 12 can approach the local maximum.

The throttle opening degree of the third flow-control valve 15c, that is, the control signal (control pulse) output to the third flow-control valve 15c is set to a reference opening degree for heating that is stored in advance in the air conditioning controller 40.

The control signal output to the electric actuator for driving the air mix door 34 is determined such that the entire flow of the air after passage through the interior evaporator 21 flows through the air passage on the side of the interior condenser 12.

Accordingly, the state of the refrigerant in the ejector refrigeration circuit 10 changes as illustrated in a Mollier chart of FIG. 11 in the heating mode.

Specifically, in the heating mode, the air mix door 34 fully opens the air passage on the side of the interior condenser 12 so that the refrigerant having the high pressure and discharged from the compressor 11 flows into the interior condenser 12 (point a11 in FIG. 11), exchanges heat with the air, and radiates heat (from point a11 to point b11 in FIG. 11). The air is heated as a result. The refrigerant flowing out of the interior condenser 12 flows into the first flow-control valve 15a via the first four-way valve 13a and is decompressed (from point b11 to point r11 in FIG. 11). As a result, the dryness x of the refrigerant flowing into the heating-side nozzle 16a is adjusted to 0.5 or higher and 0.8 or lower.

The refrigerant decompressed by the first flow-control valve 15a flows into the heating-side nozzle 16a of the heating ejector 16. The refrigerant flowing into the heating-side nozzle 16a is isentropically decompressed and injected (from point r11 to point s11 in FIG. 11). The refrigerant flowing out of the one refrigerant port of the exterior heat exchanger 17 is drawn into the heating-side suction port 16c of the heating ejector 16 by the suction force of the heating-side injected refrigerant.

The heating-side injected refrigerant from the heating-side nozzle 16a and the heating-side suction refrigerant through the heating-side suction port 16c of the heating ejector 16 flow into the heating-side diffuser 16d (from point s11 to point t11 and from point c11 to point t11 in FIG. 11).

The increase in the area of the refrigerant passage in the heating-side diffuser 16d allows the speed energy of the refrigerant to be converted into the pressure energy. As a result, the pressure of the mixture of the refrigerant injected and the heating-side suction refrigerant is increased (from point t11 to point u11 in FIG. 11). The refrigerant flowing out of the heating-side diffuser 16d flows into the heating-side accumulator 19 and is separated into the gas refrigerant and the liquid refrigerant.

The liquid refrigerant separated by the heating-side accumulator 19 (point ell in FIG. 11) flows into the third flow-control valve 15c in the throttled state, and is decompressed (from point ell to point d11 in FIG. 11). The refrigerant decompressed by the third flow-control valve 15c flows into the other refrigerant port of the exterior heat exchanger 17, absorbs heat from the outside air supplied by the blower fan, and evaporates (from point d11 to point c11 in FIG. 11).

The gas refrigerant separated by the heating-side accumulator 19 (point f11 in FIG. 11) is drawn into the compressor 11 via the second four-way valve 13b, the intake accumulator 24, and the like and is compressed again (from point f11 to point a11 in FIG. 11).

The heating mode can thus heat the passenger compartment by blowing the air heated by the interior condenser 12 into the passenger compartment.

Moreover, in the heating mode, the refrigerant pressurized by the heating-side diffuser 16d of the heating ejector 16 is drawn into the compressor 11. More specifically, the refrigerant circuit switch (i.e., the switching valves 13a, 13b, 18a, 18b) sets the refrigerant circuit in which the gas refrigerant flowing out of the heating-side gas-liquid separator (i.e., the heating-side accumulator 19) is drawn into the compressor 11, whereby the refrigerant pressurized by the heating-side pressure increasing portion (i.e., the heating-side diffuser 16d) can be drawn into the compressor 11. Therefore, the power consumption of the compressor 11 can be reduced to be able to improve the COP as compared with a typical refrigeration cycle system in which the refrigerant evaporating pressure of the heat exchanger (the exterior heat exchanger 17 in the heating mode) functioning as the evaporator is equal to the pressure of the refrigerant drawn into the compressor 11.

Moreover, as is apparent from the above description, the flow direction of the refrigerant through the exterior heat exchanger 17 in the first and second dehumidifying-heating modes is different from the flow direction of the refrigerant through the exterior heat exchanger 17 in the heating mode. That is, the refrigerant flows from the other refrigerant port to the one refrigerant port of the exterior heat exchanger 17 in the heating mode.

Here, the exterior heat exchanger 17 may experience frost formation when the refrigerant evaporating temperature of the exterior heat exchanger 17 reaches below freezing (0° C. or lower) in the refrigerant circuit in which the exterior heat exchanger 17 of the ejector refrigeration circuit 10 serves as an evaporator as in the second dehumidifying-heating mode and the heating mode of the ejector refrigeration circuit 10.

Such frost formation blocks the outside air passage of the exterior heat exchanger 17 to reduce the heat exchange performance of the exterior heat exchanger 17. As a result, the amount of heat absorbed from the outside air by the refrigerant in the exterior heat exchanger 17 is reduced so that the ejector refrigeration circuit 10 fails to heat the air sufficiently.

The vehicle air conditioner 1 according to the present embodiment can execute the operation in the defrosting mode to remove frost in the exterior heat exchanger 17 of the ejector refrigeration circuit 10 when frost is formed.

Specifically, the present embodiment determines that frost is formed in the exterior heat exchanger 17 when the outside-air temperature Tam is 0° C. or lower, and a value obtained by subtracting the exterior-heat-exchanger temperature Tout from the outside-air temperature Tam (Tam−Tout) is equal to or larger than a predetermined reference temperature difference. Then, the operation in the defrosting mode is executed until a predetermined reference time elapses. The operation in defrosting mode will be described below.

(e) Defrosting Mode

In the defrosting mode, the air conditioning controller 40 controls the operation of the first four-way valve 13a to set the refrigerant circuit in which the refrigerant outlet of the interior condenser 12 is connected to the first three-way joint 14a and at the same time the second four-way valve 13b is connected to the third three-way joint 14c. The air conditioning controller 40 also controls the operation of the second four-way valve 13b to set the refrigerant circuit in which the gas-refrigerant port of the heating-side accumulator 19 is connected to the inlet of the intake accumulator 24 and at the same time the gas-refrigerant port of the cooling-side accumulator 23 is connected to the first four-way valve 13a.

The air conditioning controller 40 further controls the first flow-control valve 15a to be fully closed, the second flow-control valve 15b to be throttled, the third flow-control valve 15c to be fully open, and the first switching valve 18a to be closed.

Thus, as indicated by solid arrows in FIG. 6, the defrosting mode forms the refrigeration cycle in which the refrigerant is circulated in the order of the compressor 11, the interior condenser 12, the second flow-control valve 15b, the exterior heat exchanger 17, (the third flow-control valve 15c) the heating-side accumulator 19, the intake accumulator 24, and the compressor 11.

The air conditioning controller 40 determines the operating state of each of the various controlled devices (a control signal output to each of the various controlled devices) on the basis of the target supply-air temperature TAO, the signals detected by the group of sensors, and the like in the refrigerant circuit above.

For example, the refrigerant discharge capacity of the compressor 11, that is, the control signal output to the electric motor of the compressor 11, is determined such that the refrigerant discharge capacity for defrosting stored in advance in the air conditioning controller 40 is exerted. The throttle opening degree of the second flow-control valve 15b, that is, the control signal (control pulse) output to the second flow-control valve 15b is set to a reference opening degree for defrosting that is stored in advance in the air conditioning controller 40.

The control signal output to the electric actuator for driving the air mix door 34 is determined such that the air mix door 34 blocks the air passage on the side of the interior condenser 12 to allow the entire flow of the air after passage through the interior evaporator 21 to flow around the interior condenser 12.

Accordingly, the state of the refrigerant in the ejector refrigeration circuit 10 changes as illustrated in a Mollier chart of FIG. 12 in the defrosting mode.

Specifically, the refrigerant having the high pressure and discharged from the compressor 11 flows into the interior condenser 12 (point a12 in FIG. 12). At this time, the air passage on the side of the interior condenser 12 is blocked by the air mix door 34 so that the refrigerant flowing into the interior condenser 12 flows out of the interior condenser 12 with almost no heat exchange with the air.

The refrigerant flowing out of the interior condenser 12 flows into the second flow-control valve 15b via the first four-way valve 13a, and is decompressed (from point a12 to point c12 in FIG. 12). The refrigerant decompressed by the second flow-control valve 15b flows into the one refrigerant port of the exterior heat exchanger 17 and radiates heat to the exterior heat exchanger 17 (from point c12 to point f12 in FIG. 12). The exterior heat exchanger 17 is defrosted as a result.

The refrigerant flowing out of the exterior heat exchanger 17 is drawn into the compressor 11 via the second flow-control valve 15b that is fully open, the heating-side accumulator 19, the second four-way valve 13b, and the intake accumulator 24 and is compressed again (from point f12 to point a12 in FIG. 12).

As described above, the ejector refrigeration circuit 10 of the present embodiment can implement proper air conditioning inside the passenger compartment by switching the operation of the vehicle air conditioner 1 among the cooling mode, the first dehumidifying-heating mode, the second dehumidifying-heating mode, and the heating mode. The ejector refrigeration circuit 10 of the present embodiment can also set the refrigerant circuit in the defrosting mode to be able to remove frost formed in the exterior heat exchanger 17 in the event of frost formation.

The ejector refrigeration circuit 10 of the present embodiment can also expand the temperature adjustment range of the air at the time of dehumidifying and heating the passenger compartment.

More specifically, a conventional ejector refrigeration circuit is required to maintain the refrigerant pressure in the exterior heat exchanger at a predetermined value or higher in order to operate the ejector refrigeration circuit properly at the time of performing dehumidifying and heating by connecting the exterior heat exchanger and the interior evaporator in series with respect to the refrigerant flow. For this reason, the temperature of the air blown into the passenger compartment (supply-air temperature) cannot be adjusted in a certain range at the time of dehumidifying and heating.

Specifically, the conventional ejector refrigeration circuit can adjust the supply-air temperature within range A of FIG. 13 when switching to the refrigerant circuit in which the exterior heat exchanger and the interior evaporator are connected in series with respect to the refrigerant flow. The supply-air temperature can be adjusted within range C of FIG. 13 when the conventional ejector refrigeration circuit sets the refrigerant circuit in which the exterior heat exchanger and the interior evaporator are connected in parallel with respect to the refrigerant flow.

In other words, the conventional ejector refrigeration circuit cannot adjust the supply-air temperature within range B of FIG. 13.

On the other hand, the ejector refrigeration circuit 10 of the present embodiment sets the refrigerant circuit in which the exterior heat exchanger 17 and the interior evaporator 21 are connected in series with respect to the refrigerant flow in the first and second dehumidifying-heating modes. The refrigerant can thus be supplied to the exterior heat exchanger 17 and the interior evaporator 21 reliably by the suction and discharge action of the compressor 11 regardless of the refrigerant pressure in the exterior heat exchanger 17.

In the first dehumidifying-heating mode, the exterior heat exchanger 17 is disposed upstream of the interior evaporator 21 along the refrigerant flow via the fifth flow-control valve 15e which is the second decompressor, so that the temperature of the refrigerant in the exterior heat exchanger 17 can be adjusted in a temperature range higher than that of the refrigerant in the interior evaporator 21.

The amount of heat radiated by the refrigerant in the interior condenser 12 can thus be adjusted by adjusting the throttle opening degree of the fifth flow-control valve 15e and adjusting the amount of heat absorbed or radiated by the refrigerant in the exterior heat exchanger 17. As a result, the range in which the supply-air temperature can be adjusted is found to be expanded to range D of FIG. 13 in the first dehumidifying-heating mode.

In the second dehumidifying-heating mode, the exterior heat exchanger 17 is disposed downstream of the interior evaporator 21 along the refrigerant flow via the second flow-control valve 15b which is the first decompressor, so that the temperature of the refrigerant in the exterior heat exchanger 17 can be in a temperature range lower than that of the refrigerant in the interior evaporator 21.

The interior condenser 12 can thus heat the air with the heating capacity higher than that in the first dehumidifying-heating mode by adjusting the throttle opening degree of the second flow-control valve 15b and increasing the amount of heat absorbed by the refrigerant in the exterior heat exchanger 17. As a result, the range in which the supply-air temperature can be adjusted is found to be expanded to range E of FIG. 13 in the second dehumidifying-heating mode.

As a result, the ejector refrigeration circuit 10 of the present embodiment can adjust the temperature of the air within the wide temperature range by switching between the first dehumidifying-heating mode and the second dehumidifying-heating mode at the time of dehumidifying and heating the passenger compartment.

In the ejector refrigeration circuit 10 of the present embodiment, the flow direction of the refrigerant through the exterior heat exchanger 17 in the first and second dehumidifying-heating modes is different from the flow direction of the refrigerant through the exterior heat exchanger 17 in the heating mode. It is thus possible to prevent the refrigerant oil from staying in the exterior heat exchanger 17 by varying the mode of flow of the refrigerant through the exterior heat exchanger 17 in the first and second dehumidifying-heating modes and the mode of flow of the refrigerant through the exterior heat exchanger 17 in the heating mode.

Specifically, in the present embodiment, the cross-sectional area of the refrigerant passage defined in the exterior heat exchanger 17 is reduced from a refrigerant inlet (i.e., the other refrigerant port) toward a refrigerant outlet (i.e., the one refrigerant port) in the heating mode. As a result, the flow rate of the refrigerant flowing through the exterior heat exchanger 17 in the heating mode is increased to be able to prevent the refrigerant oil from staying in the exterior heat exchanger 17.

More specifically, the exterior heat exchanger 17 serves as an evaporator in the heating mode. The liquid refrigerant vaporizes while flowing through the refrigerant passage in the exterior heat exchanger 17 from the refrigerant inlet toward the refrigerant outlet, whereby the density of the refrigerant decreases. Thus, the reduction in the cross-sectional area of the refrigerant passage from the refrigerant inlet toward the refrigerant outlet of the exterior heat exchanger 17 can increase the flow rate of the refrigerant flowing through the exterior heat exchanger 17 and discharge the refrigerant oil staying in the exterior heat exchanger 17 out of the exterior heat exchanger 17.

In the ejector refrigeration circuit 10 of the present embodiment, the flow direction of the refrigerant through the interior evaporator 21 in the first and second dehumidifying-heating modes is different from the flow direction of the refrigerant through the interior evaporator 21 in the cooling mode. It is thus possible to prevent the refrigerant oil from staying in the interior evaporator 21 by varying the mode of flow of the refrigerant through the interior evaporator 21 in the first and second dehumidifying-heating modes and the mode of flow of the refrigerant through the interior evaporator 21 in the cooling mode.

More specifically, the interior evaporator 21 serves as an evaporator in the cooling mode. The liquid refrigerant vaporizes while flowing through the refrigerant passage in the interior evaporator 21 from the refrigerant inlet toward the refrigerant outlet, whereby the density of the refrigerant decreases. Thus, the reduction in the cross-sectional area of the refrigerant passage from the refrigerant inlet toward the refrigerant outlet of the interior evaporator 21 can increase the flow rate of the refrigerant flowing through the interior evaporator 21 and discharge the refrigerant oil staying in the interior evaporator 21 out of the interior evaporator 21.

That is, the ejector refrigeration circuit 10 of the present embodiment applied to the air conditioner that performs dehumidifying and heating can expand the temperature adjustment range of the air blown into the air-conditioning object space at the time of dehumidifying and heating while preventing the refrigerant oil from staying in the exterior heat exchanger 17 and the interior evaporator 21.

The present disclosure is not limited to the above-described embodiments, and can be appropriately modified. Individual elements or features of a particular embodiment are generally not limited to that particular embodiment, but, where applicable, are interchangeable and can be used in a selected embodiment, even if not specifically shown or described. Individual elements or features of a particular embodiment are not necessarily essential unless it is specifically stated that the elements or the features are essential in the foregoing description, or unless the elements or the features are obviously essential in principle.

A quantity, a value, an amount, a range, or the like, if specified in the above-described example embodiments, is not necessarily limited to the specific value, amount, range, or the like unless it is specifically stated that the value, amount, range, or the like is necessarily the specific value, amount, range, or the like, or unless the value, amount, range, or the like is obviously necessary to be the specific value, amount, range, or the like in principle. Furthermore, a material, a shape, a positional relationship, or the like, if specified in the above-described example embodiments, is not necessarily limited to the specific material, shape, positional relationship, or the like unless it is specifically stated that the material, shape, positional relationship, or the like is necessarily the specific material, shape, positional relationship, or the like, or unless the material, shape, positional relationship, or the like is obviously necessary to be the specific material, shape, positional relationship, or the like in principle.

(1) Although the above embodiment describes the example in which the ejector refrigeration circuit 10 according to the present disclosure is applied to the air conditioner for an electric vehicle, the application of the ejector refrigeration circuit 10 is not limited thereto. For example, the ejector refrigeration circuit may be applied to an air conditioner of a common vehicle that gains vehicle driving force from an internal combustion engine (engine), or an air conditioner of a hybrid vehicle that gains vehicle driving force from both an internal combustion engine and a driving electric motor.

When the ejector refrigeration circuit is applied to the vehicle with the internal combustion engine, a heater core that heats the air by using coolant of the internal combustion engine as a heat source may be provided as an auxiliary air heater in the vehicle air conditioner 1. The ejector refrigeration circuit may be applied to not only the vehicle air conditioner but also a stationary air conditioner.

Although the above embodiment describes the ejector refrigeration circuit 10 that directly heats the air using the refrigerant discharged from the compressor 11 as a heat source by exchanging heat between the refrigerant discharged from the compressor 11 and the air in the interior condenser 12, the air may be heated differently in the interior condenser 12.

For example, a heating medium circulation circuit for circulating a heating medium may be provided, an interior radiator may be configured as a water-refrigerant heat exchanger that exchanges heat between the refrigerant discharged from the compressor and the heating medium, and a heating heat exchanger that heats the air by exchanging heat between the heating medium heated by the interior radiator and the air may be disposed in the heating medium circulation circuit. That is, the interior radiator may indirectly heat the air via the heating medium using the refrigerant discharged from the compressor (refrigerant on the high pressure side of the cycle) as the heat source.

Alternatively, when the ejector refrigeration circuit is applied to the vehicle with the internal combustion engine, the coolant of the internal combustion engine may be used as the heating medium and circulated through the heating medium circulation circuit. In an electric vehicle, the coolant for cooling a battery or an electric device may be used as the heating medium and circulated through the heating medium circulation circuit.

(2) Although the above embodiment describes the example in which the cross-sectional area of the refrigerant passage defined in each of the exterior heat exchanger 17 and the interior evaporator 21 is changed gradually by changing the configuration of the passage, the mode of flow of the refrigerant through the exterior heat exchanger 17 and the interior evaporator 21 in the operation modes may be changed by another method. For example, the exterior heat exchanger 17 and the interior evaporator 21 may each be formed by using a plurality of types of tubes having different passage sectional areas.

Moreover, although the above embodiment describes the example in which the cross-sectional area of the refrigerant passage formed in the exterior heat exchanger 17 is reduced from the other refrigerant port toward the one refrigerant port, the cross-sectional area of the passage may be changed differently.

For example, the cross-sectional area of the refrigerant passage may be increased from the other refrigerant port toward the one refrigerant port as long as the flow direction of the refrigerant through the exterior heat exchanger 17 in the first and second dehumidifying-heating modes is different from the flow direction of the refrigerant through the exterior heat exchanger 17 in the heating mode to allow the refrigerant oil in the exterior heat exchanger 17 to be discharged in any of the operation modes. That is, the cross-sectional area of the refrigerant passage defined in the exterior heat exchanger 17 may be increased from the refrigerant inlet toward the refrigerant outlet in the heating mode.

With the cross-sectional area of the refrigerant passage increasing from the refrigerant inlet toward the refrigerant outlet in the heating mode in which the exterior heat exchanger 17 serves as an evaporator, a pressure loss can be decreased at the time the refrigerant flows through the exterior heat exchanger 17. The similar applies to the interior evaporator 21. That is, the cross-sectional area of the refrigerant passage defined in the interior evaporator 21 may be increased from the refrigerant inlet toward the refrigerant outlet in the cooling mode.

(3) The components making up the ejector refrigeration circuit 10 are not limited to those disclosed in the above embodiment.

For example, the above embodiment describes the example in which the electric compressor is adopted as the compressor 11, but the compressor 11 is not limited thereto. An engine-driven variable capacity compressor or the like may be adopted as the compressor 11, for example.

The above embodiment describes the example in which the air is heated by heat exchange between the refrigerant having the high pressure and the air in the interior condenser 12. Alternatively, for example, a heating medium circulation circuit for circulating a heating medium may be provided instead of the interior condenser 12, and a water-refrigerant heat exchanger that exchanges heat between the refrigerant having the high pressure and the heating medium, a heating heat exchanger that heats the air by exchanging heat between the heating medium heated by the water-refrigerant heat exchanger and the air, and the like may be disposed in the heating medium circulation circuit.

Although the above embodiment describes the example in which the plurality of flow-control valves and switching valves is adopted as the refrigerant circuit switches, the refrigerant circuit switches are not limited thereto. For example, a combination of a flow-control valve without a fully closed function and an switching valve, a four-way valve, and the like may be adopted as long as the refrigerant circuit switches can set at least the refrigerant circuit in the heating mode and the refrigerant circuit in the series dehumidifying-heating mode.

Alternatively, the components described in the above embodiment may be integrated. For example, the first flow-control valve 15a, the heating ejector 16, the heating-side accumulator 19, and the like may be integrated (modularized). In such a case, a valve body having a needle or cone shape may be disposed in the passage of the heating-side nozzle 16a of the heating ejector 16 to exert the function similar to that of the first flow-control valve 15a by displacing the valve body.

Similarly, the fourth flow-control valve 15d, the cooling ejector 22, the cooling-side accumulator 23, and the like may be integrated (modularized).

Moreover, an evaporating pressure regulating valve that adjusts the refrigerant evaporating pressure of the interior evaporator 21 to a predetermined value or higher may be disposed on the refrigerant outlet side of the interior evaporator 21 of the ejector refrigeration circuit 10 in the above embodiment. As a result, frosting on the interior evaporator 21 can be more reliably prevented by a mechanical mechanism.

The above embodiment describes the example in which R134a is adopted as the refrigerant, but the refrigerant is not limited thereto. For example, R1234yf, R600a, R410A, R404A, R32, R407C, or the like may be adopted. Alternatively, a mixed refrigerant obtained by mixing a plurality of these refrigerants may be adopted.

(4) The above embodiment describes the example in which the valve opening degree of the first flow-control valve 15a is adjusted on the basis of the refrigerant discharge capacity of the compressor 11 during the high heating capacity operation in the heating mode, but the valve opening degree of the first flow-control valve 15a may be adjusted differently.

For example, a dryness sensor for detecting dryness of the refrigerant on the outlet side of the interior condenser 12 may be provided, and the valve opening degree of the first flow-control valve 15a may be adjusted such that a value detected by the dryness sensor is 0.5 or higher and 0.8 or lower. Alternatively, the valve opening degree of the first flow-control valve 15a may be adjusted such that the COP of the ejector refrigeration circuit 10 approaches the local maximum.

(5) The above embodiment describes the example in which the operation modes are switched by executing the air conditioning control program, but the operation modes may be switched differently. For example, an operation mode setting switch for setting each operation mode may be provided on the operation panel 50 to set each operation mode in response to an operation signal from the operation mode setting switch.

Claims

1. An ejector refrigeration circuit for an air conditioner, comprising:

a compressor that compresses a refrigerant mixed with a refrigerant oil to be the refrigerant having a high pressure and discharges the refrigerant having the high pressure;

a heating heat exchanger that heats air flowing to an air-conditioning object space by using the refrigerant having the high pressure as a heat source;

a first decompressor that is disposed downstream of the heating heat exchanger and decompresses the refrigerant;

an exterior heat exchanger that exchanges heat between the refrigerant flowing out of the first decompressor and an outside air;

a second decompressor that is disposed downstream of the heating heat exchanger and decompresses the refrigerant;

a cooling heat exchanger that is configured to evaporate the refrigerant flowing out of the second decompressor and to cool the air before passing through the heating heat exchanger;

a heating ejector that includes: a heating-side nozzle that is disposed downstream of the heating heat exchanger, decompresses the refrigerant, and injects the refrigerant as a heating-side injected refrigerant; a heating-side suction port that draws in the refrigerant as a heating-side suction refrigerant by suction force of the heating-side injected refrigerant; and a heating-side pressure increasing portion that pressurizes a mixed refrigerant of the heating-side injected refrigerant and the heating-side suction refrigerant;

a heating-side gas-liquid separator that separates the refrigerant flowing out of the heating-side pressure increasing portion into a gas refrigerant and a liquid refrigerant; and

a refrigerant circuit switch that is configured to set a plurality of refrigerant circuits, wherein

the refrigerant circuit switch is configured to set a refrigerant circuit that allows the refrigerant flowing out of the heating heat exchanger to flow through in order of the first decompressor, the exterior heat exchanger, the second decompressor, the cooling heat exchanger, and the compressor in a first dehumidifying-heating mode in which the heating heat exchanger reheats the air cooled by the cooling heat exchanger, set a refrigerant circuit that allows the refrigerant flowing out of the heating heat exchanger to flow through in order of the second decompressor, the cooling heat exchanger, the first decompressor, the exterior heat exchanger, and the compressor in a second dehumidifying-heating mode in which the heating heat exchanger reheats the air cooled by the cooling heat exchanger, and set a refrigerant circuit that allows the refrigerant flowing out of the heating heat exchanger to flow into the heating-side nozzle, allows the gas refrigerant flowing out of the heating-side gas-liquid separator to be drawn into the compressor, allows the liquid refrigerant flowing out of the heating-side gas-liquid separator to flow into the exterior heat exchanger, and allows the refrigerant flowing out of the exterior heat exchanger to be drawn into the heating-side suction port in a heating mode in which the heating heat exchanger heats the air,

a flow direction of the refrigerant through the exterior heat exchanger in the first dehumidifying-heating mode is the same as a flow direction of the refrigerant through the exterior heat exchanger in the second dehumidifying-heating mode, and

the flow direction of the refrigerant through the exterior heat exchanger in the first dehumidifying-heating mode is different from a flow direction of the refrigerant through the exterior heat exchanger in the heating mode.

2. The ejector refrigeration circuit according to claim 1, wherein

the exterior heat exchanger defines a refrigerant passage therein, and

the refrigerant passage has a cross-sectional area decreasing from a refrigerant inlet toward a refrigerant outlet in the heating mode.

3. The ejector refrigeration circuit according to claim 1, further comprising:

a cooling ejector including a cooling-side nozzle that is disposed downstream of the heating heat exchanger, decompresses the refrigerant, and injects the refrigerant as a cooling-side injected refrigerant, a cooling-side suction port that draws in the refrigerant through the cooling-side suction port as a cooling-side suction refrigerant by suction force of the cooling-side injected refrigerant, and a cooling-side pressure increasing portion that pressurizes a mixed refrigerant of the cooling-side injected refrigerant and the cooling-side suction refrigerant; and

a cooling-side gas-liquid separator that separates the refrigerant flowing out of the cooling-side pressure increasing portion into a gas refrigerant and a liquid refrigerant, wherein

the refrigerant circuit switch sets a refrigerant circuit that allows the refrigerant flowing out of the exterior heat exchanger to flow into the cooling-side nozzle, allows the gas refrigerant flowing out of the cooling-side gas-liquid separator to be drawn into the compressor, allows the liquid refrigerant flowing out of the cooling-side gas-liquid separator to flow into the cooling heat exchanger, and allows the refrigerant flowing out of the cooling heat exchanger to be drawn into the cooling-side suction port in a cooling mode in which the cooling heat exchanger cools the air,

a flow direction of the refrigerant through the cooling heat exchanger in the first dehumidifying-heating mode is the same as a flow direction of the refrigerant through the cooling heat exchanger in the second dehumidifying-heating mode, and

the flow direction of the refrigerant through the cooling heat exchanger in the first dehumidifying-heating mode is different from a flow direction of the refrigerant through the cooling heat exchanger in the cooling mode.

4. The ejector refrigeration circuit according to claim 3, wherein

the cooling heat exchanger defines a refrigerant passage therein, and

the refrigerant passage has a cross-sectional area decreasing from a refrigerant inlet toward a refrigerant outlet in the cooling mode.

5. An ejector refrigeration circuit for an air conditioner, comprising:

a compressor that compresses a refrigerant mixed with a refrigerant oil to be the refrigerant having a high pressure and discharges the refrigerant having the high pressure;

a heating heat exchanger that heats air to be blown into an air-conditioning object space by using the refrigerant having the high pressure as a heat source;

a first decompressor that is disposed downstream of the heating heat exchanger and decompresses the refrigerant;

an exterior heat exchanger that exchanges heat between the refrigerant flowing out of the first decompressor and an outside air;

a second decompressor that is disposed downstream of the heating heat exchanger and decompresses the refrigerant;

a cooling heat exchanger that is configured to evaporate the refrigerant flowing out of the second decompressor and to cool the air before passing through the heating heat exchanger;

a cooling ejector including a cooling-side nozzle that decompresses the refrigerant downstream of the heating heat exchanger and injects the refrigerant as a cooling-side injected refrigerant, a cooling-side suction port that draws in the refrigerant through the cooling-side suction port as a cooling-side suction refrigerant by suction force of the cooling-side injected refrigerant, and a cooling-side pressure increasing portion that pressurizes a mixed refrigerant of the cooling-side injected refrigerant and the cooling-side suction refrigerant;

a cooling-side gas-liquid separator that separates the refrigerant flowing out of the cooling-side pressure increasing portion into a gas refrigerant and a liquid refrigerant; and

a refrigerant circuit switch that is configured to set a plurality of refrigerant circuits, wherein

the refrigerant circuit switch is configured to set a refrigerant circuit that allows the refrigerant flowing out of the heating heat exchanger to flow through in order of the first decompressor, the exterior heat exchanger, the second decompressor, the cooling heat exchanger, and the compressor in a first dehumidifying-heating mode in which the heating heat exchanger reheats the air cooled by the cooling heat exchanger, set a refrigerant circuit that allows the refrigerant flowing out of the heating heat exchanger to flow through in order of the second decompressor, the cooling heat exchanger, the first decompressor, the exterior heat exchanger, and the compressor in a second dehumidifying-heating mode in which the heating heat exchanger reheats the air cooled by the cooling heat exchanger, and set a refrigerant circuit that allows the refrigerant flowing out of the exterior heat exchanger to flow into the cooling-side nozzle, allows the gas refrigerant flowing out of the cooling-side gas-liquid separator to be drawn into the compressor, allows the liquid refrigerant flowing out of the cooling-side gas-liquid separator to flow into the cooling heat exchanger, and allows the refrigerant flowing out of the cooling heat exchanger to be drawn into the cooling-side suction port in a cooling mode in which the cooling heat exchanger cools the air,

a flow direction of the refrigerant through the cooling heat exchanger in the first dehumidifying-heating mode is the same as a flow direction of the refrigerant through the cooling heat exchanger in the second dehumidifying-heating mode, and

the flow direction of the refrigerant through the cooling heat exchanger in the first dehumidifying-heating mode is different from a flow direction of the refrigerant through the cooling heat exchanger in the cooling mode.

6. The ejector refrigeration circuit according to claim 4, wherein

the cooling heat exchanger defines a refrigerant passage therein, and

the refrigerant passage has a cross-sectional area decreasing from a refrigerant inlet toward a refrigerant outlet in the cooling mode.