HEAT EXCHANGER

Abstract

A heat exchanger includes a refrigerant condensing part including tubes and fins. A refrigerant is to flow in the tubes to exchange heat between the refrigerant and an external gas to flow outside the tubes. The fins are connected to the tubes. A gas/liquid separating part is to separate the refrigerant into gas and liquid. A refrigerant supercooling part is to exchange heat between the refrigerant and the external gas. The refrigerant supercooling part includes an inlet and an outlet. The refrigerant is to flow into the refrigerant supercooling part from the inlet. The refrigerant is to flow out of the refrigerant supercooling part from the outlet. The refrigerant flows through the refrigerant condensing part, the gas/liquid separating part, and the refrigerant supercooling part in this order. The external gas flows around the refrigerant supercooling part and then flows around the refrigerant condensing part.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application claims priority under 35 U.S.C. §119 to Japanese Patent Application No. 2010-057192, filed on Mar. 15, 2010, entitled “Heat Exchanger.” The contents of this application are incorporated herein by reference in their entirety.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a heat exchanger.

2. Description of the Related Art

Various different vehicle air conditioners corresponding to different types of vehicles that emit a relatively low amount of heat, such as fuel cell vehicles and electric vehicles are proposed. With such vehicle air conditioners, there is need for improving the ability of the heat pump, and, for example, a known technique proposes a technique of providing a supercooling part (subcooling part) downstream of a capacitor (peak) (refer to Japanese Unexamined Patent Application Publication No. 6-341736 (claim 1 and FIG. 1)).

With the technique described in Japanese Unexamined Patent Application Publication No. 6-341736, a refrigerant flows in order through a capacitor and a supercooling part to improve the heat pump capacity. However, the temperature variation in the air received from the heat exchanger has not been considered.

SUMMARY OF THE INVENTION

According to one aspect of the present invention, a heat exchanger includes a refrigerant condensing part, a gas/liquid separating part, and a refrigerant supercooling part. The refrigerant condensing part includes tubes and fins. A refrigerant is to flow in the tubes to exchange heat between the refrigerant and an external gas to flow outside the tubes. The fins are connected to the tubes. The gas/liquid separating part is to separate the refrigerant into gas and liquid. The refrigerant supercooling part is to exchange heat between the refrigerant and the external gas. The refrigerant supercooling part includes a supercooling part inlet and an outlet. The refrigerant is to flow into the refrigerant supercooling part from the supercooling part inlet. The refrigerant is to flow out of the refrigerant supercooling part from the outlet. The heat exchanger is so constructed that the refrigerant flows through the refrigerant condensing part, the gas/liquid separating part, and the refrigerant supercooling part in this order. The heat exchanger is so constructed that the external gas flows around the refrigerant supercooling part and then flows around the refrigerant condensing part.

BRIEF DESCRIPTION OF THE DRAWINGS

A more complete appreciation of the invention and many of the attendant advantages thereof will be readily obtained as the same becomes better understood by reference to the following detailed description when considered in connection with the accompanying drawings, wherein:

FIG. 1 is an exploded perspective view of a heat exchanger according to a first embodiment;

FIG. 2 is an external perspective view of the heat exchanger according to the first embodiment;

FIG. 3A is a sectional view of an upper header; and FIG. 3B is a sectional view of a lower header;

FIG. 4 is a sectional view of a connecting part of a receiver tank and a refrigerant supercooling part;

FIG. 5 illustrates, in outline, the flow of refrigerant in a heating mode when the heat exchanger of the first embodiment is applied to a vehicle air conditioner;

FIG. 6 illustrates, in outline, the flow of refrigerant in a cooling mode when the heat exchanger of the first embodiment is applied to a vehicle air conditioner;

FIGS. 7A and 7B illustrate the effect of the heat exchanger of the first embodiment, where FIG. 7A illustrates the first embodiment, and FIG. 7B illustrates a comparative example;

FIGS. 8A, 8B, and 8C illustrate a heat exchanger according to a second embodiment, where FIG. 8A is a partially omitted perspective view, FIG. 8B is a sectional view taken along line VIIIB-VIIIB in FIG. 8A, and FIG. 8C is s sectional view taken along line VIIIC-VIIIC in FIG. 8A;

FIGS. 9A and 9B illustrate a heat exchanger according to a third embodiment, where FIG. 9A is a longitudinal sectional view, and FIG. 9B is a perspective view of the configuration of a tube;

FIGS. 10A and 10B are sectional views of a connecting part of a refrigerant condensing part, a refrigerant supercooling part, and a receiver tank, where FIG. 10A is a variation, and FIG. 10B is another variation; and

FIGS. 11A and 11B illustrate variations in the internal structure of the tube; and FIGS. 11C to 11F illustrate variations in the sectional structure of a header.

DESCRIPTION OF THE EMBODIMENTS

Embodiments of the present invention will be described with reference to the drawings, wherein like reference numerals designate corresponding or identical elements throughout the various drawings. As illustrated in FIGS. 1 and 2, a heat exchanger 20 according to a first embodiment includes a refrigerant condensing part 21, a receiver tank (gas/liquid separating part) 22, and a refrigerant supercooling part 23. The refrigerant supercooling part 23 is stacked on the refrigerant condensing part 21.

The refrigerant condensing part 21 includes tubes 21a extending in the vertical direction arranged at regular intervals and corrugated radiator fins (fins) 21b disposed between the tubes 21a. The tubes 21a and the radiator fins 21b are made of a metal having high heat conductivity (radiation performance), such as aluminum or copper.

The refrigerant condensing part 21 includes, in the top area, an upper header 21c that distributes a refrigerant discharged from a compressor 10, which is described below, to the tubes 21a and, in the bottom area, a lower header 21d where the refrigerant that has passed through the tubes 21a is collected. Details of the upper header 21c and the lower header 21d will be described below.

A receiver tank 22 is disposed on a side of the refrigerant condensing part 21 and the refrigerant supercooling part 23 (see FIG. 2) and has a function (liquid/gas separating function) of separating a refrigerant liquefied by the refrigerant condensing part 21 (liquid refrigerant) and a refrigerant not liquefied (gas refrigerant).

The receiver tank 22 is a vertical cylinder and includes a tank portion 22a that separately retains the liquid refrigerant and the gas refrigerant. Water contained in the refrigerant introduced to the tank portion 22a may be removed. In this embodiment, for example, the bottom surface inside the tank portion 22a may be covered with a desiccant to remove water.

The refrigerant supercooling part 23 performs heat exchange between the liquid refrigerant from the receiver tank 22 and air-conditioning air (external gas) A to further cool the liquid refrigerant to a complete liquefied.

The refrigerant supercooling part 23 includes a tube 23a made of the same material as the refrigerant condensing part 21 and radiator fins 23b that covers the tube 23a.

The tube 23a extends horizontally and is bent in a U-shape at both ends of the refrigerant condensing part 21 in a meandering manner from bottom to top.

The radiator fins 23b are longitudinal plate-liken fins arranged in parallel to cover the periphery of the meandering tube 23a.

The shape of the radiator fins 21b of the refrigerant condensing part 21 and the radiator fins 23b of the refrigerant supercooling part 23 is not particularly limited so long as the air-conditioning air A can pass through between the radiator fins 21b of the refrigerant condensing part 21 and between the radiator fins 23b of the refrigerant supercooling part 23. Various modifications may be made. For example, both the radiator fins 21b and the radiator fins 23b may be corrugated fins.

As illustrated in FIG. 3A, there is a space inside the upper header 21c where the refrigerant flows horizontally. The upper ends of the tubes 21a are inserted into through-holes 21c1 in the bottom surface of the upper header 21c to join the upper header 21c and the tubes 21a. In this way, the refrigerant is guided from the compressor 10 to the upper header 21c are distributed to the tubes 21a, as indicted by the arrows, and flows downward.

As illustrated in FIG. 3B, there is a space inside the lower header 21d where the refrigerant flows horizontally. The lower ends of the tubes 21a are inserted into through-holes 21d1 in the upper surface of the lower header 21d to join the tubes 21a and the lower header 21d.

The lower header 21d is connected to the receiver tank 22 via a pipe 22b. The pipe 22b penetrates the bottom of the tank portion 22a upward into the tank portion 22a by a predetermined length. The predetermined length is preferably set to a length that the liquid surface of the retained refrigerant does not exceed the tip (upper edge) of the pipe 22b. In FIG. 3A, the predetermined length appears shorter than it actually is for the sake of description.

The lower header 21d is connected to a capacitor 30, which is described below, via a pipe a2 that extends away from the receiver tank 22 (see FIG. 6). In this embodiment, the lower header 21d constitutes a branching channel.

As illustrated in FIG. 4, the refrigerant supercooling part 23 is connected to the receiver tank 22 via a pipe 22c. The pipe 22c extends downward from the bottom of the receiver tank 22 and is connected to an inlet 23a1 (introducing part 23c) of the tube 23a of the refrigerant supercooling part 23.

The heat exchanger 20 having such a configuration can be used as a vehicle air conditioner 1A of a vehicle V, such as an electric vehicle (EV), a fuel cell vehicle (FCV), or a hybrid electric vehicle (HEV).

As illustrated in FIGS. 5 and 6, the vehicle air conditioner 1A includes the compressor 10, the heat exchanger 20, the capacitor 30, an automatic expansion valve 40, a first evaporator 50, a second evaporator 60, a cooler/heater switching unit 70, and an electronic control unit (ECU) 80.

The compressor 10 is driven by a motor (or an engine) to take in and compress a refrigerant, and discharge a high-temperature, high-pressure refrigerant to the heat exchanger 20.

The capacitor 30 includes a condensing part 31 and a receiver tank 32 and is disposed inside the front hood of the vehicle V. The refrigerant flowing through the condensing part 31 exchanges (radiates) heat with (to) the outside air introduced through the front of the vehicle V. The condensing part 31 includes a plurality of tubes (not shown) extending transversely and radiator fins (not shown).

The receiver tank 32 is disposed on one side of the condensing part 31 and is shaped as a cylinder, such as that of the receiver tank 22. The receiver tank 32 has a function (liquid/gas separating function) of separating the liquid refrigerant and the gas refrigerant in the condensing part 31 during cooling.

The opening of the automatic expansion valve 40 can be changed in accordance with the refrigerant temperature. The automatic expansion valve 40 includes a detector (not shown) that detects the temperature and pressure of the refrigerant that flowed out from the first evaporator 50 (or second evaporator 60), which is described below. The opening of the automatic expansion valve 40 is changed in accordance with the temperature and pressure of the refrigerant that flowed out from the first evaporator 50 (or second evaporator 60) to change the flow rate of the refrigerant.

The refrigerant flowing through the first evaporator 50 exchanges heat with the air-conditioning air A (heat source) discharged from the vehicle interior C. The first evaporator 50 is disposed in the rear area, such as a luggage compartment D (trunk), of the vehicle V where the air-conditioning air A is discharged outside the vehicle. The first evaporator 50 takes in heat from the air-conditioning air A (heat source) discharged from the vehicle interior C of the vehicle V to the outside of the vehicle through the refrigerant during heating. The heat source is not limited to the air-conditioning air A discharged from the vehicle interior C, and instead, exhaust heat from the driving part (for example, the motor) of the vehicle V may be used.

The second evaporator 60 is disposed in the vehicle interior C and performs heat exchange between the refrigerant and the air-conditioning air A. The second evaporator 60 is disposed upstream of the heat exchanger 20 along the flow of the air-conditioning air A.

A refrigerant discharge port 10b of the compressor 10 is connected to a refrigerant inlet 21a1 of the refrigerant condensing part 21 via a pipe a1, and a refrigerant outlet 21a2 of the refrigerant condensing part 21 is connected to a refrigerant inlet 30a of the capacitor 30 via a pipe a2, which has an electromagnetic valve V1. The electromagnetic valve V1 constitutes a capacitor blocking unit that blocks the flow of the refrigerant to the capacitor 30 by closing.

A refrigerant outlet 30b of the capacitor 30 is connected to a decompression-side inlet 40a of the automatic expansion valve 40 via a pipe a3 having a check valve V2. A decompression-side outlet 40b of the automatic expansion valve 40 is connected to a refrigerant inlet 50a of the first evaporator 50 via a pipe a4. The check valve V2 restricts only the flow of the refrigerant from the capacitor 30 to the automatic expansion valve 40.

A refrigerant outlet 50b of the first evaporator 50 is connected to a refrigerant inlet 60a of the second evaporator 60 via a pipe a5. A refrigerant outlet 60b of the second evaporator 60 is connected to a temperature-detection-side inlet 40c of the automatic expansion valve 40 via a pipe a6. A temperature-detection-side outlet 40d of the automatic expansion valve 40 is connected to a refrigerant suction port 10a of the compressor 10 via a pipe a7.

An outlet 23a2 of the refrigerant supercooling part 23 of the heat exchanger 20 merges with the pipe a3 between the check valve V2 and the automatic expansion valve 40 via a pipe a8 having, in order from the upstream side, an electronic valve V3, a middle aperture S, and a check valve V4. The check valve V4 restricts only the flow of the refrigerant from the refrigerant supercooling part 23 to the automatic expansion valve 40. The electronic valve V3 constitutes a supercooling circumvention unit through which the refrigerant flow to circumvent the refrigerant supercooling part 23 by closing.

The pipe a3 between the outlet 30b of the capacitor 30 and the check valve V2 merges with the pipe a7 via a pipe a9 having, in order from the upstream side, an electronic valve V5 and a check valve V6. The check valve V6 restricts only the flow of the refrigerant from the pipe a3 to the pipe a7.

A pipe a10 having an electronic valve V7 functions as a first-evaporator circumvention unit and connects the pipe a4 and the pipe a5.

A pipe all having an electronic valve V8 functions as a second-evaporator circumvention unit and connects the pipe a5 and the pipe a6.

The cooler/heater switching unit 70 switches the flow of the refrigerant and the air-conditioning air A during heating and the flow of the refrigerant and the air-conditioning air A during cooling. The cooler/heater switching unit 70 includes the first-evaporator circumvention unit, the second-evaporator circumvention unit, the capacitor circumvention unit, the supercooling circumvention unit, and an air damper 71.

The air damper 71 is disposed in a space between the heat exchanger 20 and the second evaporator 60. In a heating mode, the air damper 71 is opened to pass the air-conditioning air A introduced from outside the vehicle to the vehicle interior C through the second evaporator 60 and through the heat exchanger 20 (see FIG. 5). In contrast, in a cooling mode, the air damper 71 is closed to prevent the air-conditioning air A introduced to the vehicle interior C from passing through the second evaporator 60 and the heat exchanger 20 (see FIG. 6).

The ECU 80 controls the opening and closing of the electromagnetic valves V1, V3, V5, V7, and V8 and controls the opening and closing of the air damper 71 to control the flow of the refrigerant and the flow of the air-conditioning air A during heating and cooling.

Next, the operation of the vehicle air conditioner 1A will be described. The vehicle V illustrated in FIG. 5 is in a heating mode, and the electromagnetic valves V1 and V7 are closed. The vehicle V illustrated in FIG. 6 is in a cooling mode, and the electronic valves V3, V5, and V8 are closed.

Operation in Heating Mode

As illustrated in FIG. 5, in a heating mode, when the compressor 10 is driven, the refrigerant sucked in through the suction port 10a of the compressor 10 and discharged from the discharge port 10b is supplied through the pipe a1 to the heat exchanger 20. In this way, a high-temperature, high-pressure refrigerant (gas) is supplied to the heat exchanger 20.

The refrigerant supplied from the compressor 10 is introduced to the refrigerant condensing part 21 of the heat exchanger 20 and exchanges heat with the air-conditioning air A introduced from outside the vehicle to the vehicle interior C while flowing through the refrigerant condensing part 21 from top to bottom (see FIG. 1). The refrigerant is cooled and condensed by the air-conditioning air A (cold outside air) to change the high-temperature gas refrigerant to a low-temperature liquid refrigerant. The temperature of the air-conditioning air A is raised by the heat emitted during condensation.

The refrigerant (liquid refrigerant) from the refrigerant condensing part 21 is introduced to the receiver tank 22 through the pipe 22b. At the receiver tank 22, the refrigerant is separated into gas and liquid, i.e., the liquid refrigerant accumulates in the bottom area of the tank portion 22a (see FIG. 1), and the gas refrigerant that was not liquefied at the refrigerant condensing part 21 accumulates in the top area of the tank portion 22a. The liquid refrigerant separated at the receiver tank 22 is sent from the bottom of the receiver tank 22 through the pipe 22c to the refrigerant supercooling part 23.

The refrigerant (liquid refrigerant) introduced to the introducing part 23c at the lower edge of the refrigerant supercooling part 23 exchanges heat with the air-conditioning air A (cold outside air) introduced to the vehicle interior C. Since the refrigerant supercooling part 23 is positioned upstream (windward) of the refrigerant condensing part 21 with respect to the flow of the air-conditioning air A, the refrigerant is further cooled by the air-conditioning air A and becomes a liquid refrigerant having a temperature lower than the condensation temperature. The processing carried out in a subcooled state.

The liquid refrigerant from a deriving part 23d disposed at the upper edge of the refrigerant supercooling part 23 passes through the middle aperture S, where it is decompressed.

The liquid refrigerant decompressed at the middle aperture S is introduced to the automatic expansion valve 40 through the pipe a3. The decompressed liquid refrigerant becomes a mixture of liquid and gas at the automatic expansion valve 40 and is then introduced to the first evaporator 50.

The first evaporator 50 performs heat exchange between the air-conditioning air A discharged from the vehicle interior C to the luggage compartment D (see FIG. 5) and the refrigerant. The refrigerant absorbs heat from the air-conditioning air A and evaporates while it passes through the first evaporator 50. In this way, the heat of the vehicle interior C can be efficiently used.

The refrigerant from the first evaporator 50 passes through a pipe all that circumvents the second evaporator 60 and then passes through the pipe a6, the automatic expansion valve 40, and the pipe a7 to return to the compressor 10.

In the vehicle air conditioner 1A in a heating mode, the ECU 80 fully opens the air damper 71 to allow the air-conditioning air A took in from outside the vehicle to pass through both the second evaporator 60 and the heat exchanger 20. Since the refrigerant circumvents the second evaporator 60, heat exchange is not performed at the second evaporator 60. At the heat exchanger 20, the air-conditioning air A is heated by the high-temperature, high-pressure refrigerant by heat emission at the refrigerant condensing part 21. As a result, warm air is introduced to the vehicle interior C.

In heating mode, the electronic valve V5 is opened by the ECU 80 such that the capacitor 30 and the suction port 10a of the compressor 10 communicate through the pipe a9. In this way, the suction force (negative pressure) generated at the suction port 10a when the compressor 10 is operated sucks the refrigerant (liquid refrigerant) remaining in the capacitor 30, such as in the receiver tank 32, through the pipe a9. Accordingly, the refrigerant can be efficiently used.

Operation in Cooling Mode

As illustrated in FIG. 6, when the compressor 10 is driven in a cooling mode, the refrigerant compressed at the compressor 10 is supplied through the pipe a1 to the heat exchanger 20. In this way, the high-temperature, high-pressure refrigerant (gas) is supplied to the heat exchanger 20.

The refrigerant supplied from the compressor 10 is introduced to the refrigerant condensing part 21 of the heat exchanger 20. However, since the air damper 71 is fully closed, heat is not exchanged with the air-conditioning air A even when the refrigerant flows through the refrigerant condensing part 21. Therefore, the air-conditioning air A is not heated by the high-temperature, high-pressure refrigerant. Since the ECU 80 opens the electromagnetic valve V1 and closes the electronic valve V3, the refrigerant that has passed through the refrigerant condensing part 21 is introduced to the capacitor 30 through the pipe a2, without flowing through the receiver tank 22 and the refrigerant supercooling part 23.

The refrigerant introduced to the capacitor 30 is cooled by exchanging heat with the outside air while it passes through the condensing part 31. The refrigerant after heat exchange is separated into gas and liquid in the receiver tank 32 to separate the liquid refrigerant. The liquid refrigerant in the receiver tank 32 is introduced to the automatic expansion valve 40 through the pipe a3.

The liquid refrigerant introduced to the automatic expansion valve 40 is decompressed to a mixture of liquid refrigerant and gas refrigerant. The refrigerant that passed through the automatic expansion valve 40 passes through the pipe a10 that circumvents the first evaporator 50 and is introduced to the second evaporator 60.

At the second evaporator 60, the air-conditioning air A is cooled by heat exchange between the air-conditioning air A introduced to the vehicle interior C and the refrigerant, i.e., by the low-temperature refrigerant cooled by the capacitor 30 absorbing heat from the air-conditioning air A while passing through the second evaporator 60, and the cooled air-conditioning air A is introduced to the vehicle interior C.

The refrigerant from the second evaporator 60 returns to the compressor 10 through the pipe a6, the automatic expansion valve 40, and the pipe a7.

Since the air damper 71 is fully closed in the vehicle air conditioner 1A in a cooling mode, the air-conditioning air A cooled at the second evaporator 60 is not heated at the heat exchanger 20. As a result, cold air is introduced to the vehicle interior C.

In a dehumidification heating mode, unlike in a heating mode, the ECU 80 closes the electronic valve V8 so that the refrigerant passes through the second evaporator 60. Steps in the operation that are the same as those in a heating mode will not be repeated.

The refrigerant introduced from the first evaporator 50 to the second evaporator 60 absorbs heat from the air-conditioning air A, and as a result, the air-conditioning air A is cooled. Then, the refrigerant from the second evaporator 60 returns to the compressor 10 through the pipe a6, the automatic expansion valve 40, and the pipe a7.

In this way, in a dehumidification heating mode, the second evaporator 60, where heat exchange is performed between the refrigerant from the first evaporator 50 and the air-conditioning air A, cools the air-conditioning air A by the refrigerant flowing into the second evaporator 60 absorbing heat. Consequently, dehumidification is performed to remove the water vapor contained in the air took in from outside (air-conditioning air A).

As described above, in the heat exchanger 20 according to the first embodiment, by extending the tubes 21a vertically to provide a downward stream of the refrigerant flowing through the refrigerant condensing part 21 and by providing the refrigerant introducing part 23c in the lower area of the refrigerant supercooling part 23 and the refrigerant deriving part 23d in the upper area to provide a upward stream of the refrigerant, the temperature of the refrigerant is lowered from top to bottom in the refrigerant condensing part 21, and the temperature of the refrigerant is lowered from bottom to top in the refrigerant supercooling part 23. Therefore, the temperature of the gas discharged from the refrigerant condensing part 21 can be uniform.

In the heat exchanger 20 according to the first embodiment, by providing an overheating region R1 at a refrigerant inlet Q1 of the refrigerant condensing part 21 (see FIG. 3A) and a supercooling region R2 at a refrigerant outlet Q2 of the refrigerant supercooling part 23 (see FIG. 1) and letting the air-conditioning air A flow through the supercooling region R2 and then through the overheating region R1, the following advantages are achieved.

As illustrated in FIG. 7A, when the cold air-conditioning air A is introduced from outside the vehicle to the refrigerant supercooling part 23, a refrigerant cooled at the refrigerant supercooling part 23 and having a temperature lower than the condensation temperature flows through the supercooling region R2, and a (gaseous) refrigerant from the compressor 10 having a temperature higher than the condensation temperature flows through the overheating region R1. Therefore, the air-conditioning air A received from the refrigerant condensing part 21 at the height of the supercooling region R2 and the overheating region R1 turns into warm wind (gas) with a predetermined temperature (for example, Ta). A refrigerant that has just been introduced to the refrigerant supercooling part 23 and has a temperature close to the condensation temperature flows through a region R3 on the refrigerant inlet side of the refrigerant supercooling part 23, and a refrigerant that has released heat at the refrigerant condensing part 21 and has a temperature close to the condensation temperature flow through a region R4 on the refrigerant outlet side of the refrigerant condensing part 21. Therefore, the air-conditioning air A received from the refrigerant condensing part 21 at the height of the regions R3 and R4 turns into warm wind (gas) having a temperature Ta, similar to that described above.

For comparison, as illustrated in FIG. 7B, when the air-conditioning air A is passed only through the refrigerant condensing part 21, a refrigerant having a temperature higher than the condensation temperature flows through a region R10 on the refrigerant inlet side, and, as a result, the air-conditioning air A received from the refrigerant condensing part 21 becomes hot; since a refrigerant having a temperature close to the condensation temperature flows through a region R20 on the refrigerant outlet side, the air-conditioning air A received from the refrigerant condensing part 21 becomes warm. Consequently, there is a temperature variation along the vertical direction of the refrigerant condensing part 21.

By letting the same air-conditioning air A flow through the overheating region R1 provided at the refrigerant inlet Q1 of the refrigerant condensing part 21 and the supercooling region R2 provided at the refrigerant outlet Q2 of the refrigerant supercooling part 23, temperature variation in other regions can be prevented, and stable heat exchange can be achieved. Here, “the same air-conditioning air A flow[ing] through” means the air-conditioning air A that exchanged heat with the refrigerant flowing through the supercooling region R2 exchanges heat with the refrigerant flowing through the overheating region R1.

In the heat exchanger 20 according to the first embodiment, as illustrated in FIG. 3B, since the lower header 21d of the refrigerant condensing part 21 is a branching channel, by closing the electronic valve V3 (see FIG. 6) in a cooling mode, the refrigerant that passed through the tubes 21a flows into the capacitor 30, without flowing into the receiver tank 22. In contrast, in a heating mode, by closing the electromagnetic valve V1 (see FIG. 5), the refrigerant that passed through the tubes 21a flows to the receiver tank 22, without being directed to the capacitor 30, and is introduced to the automatic expansion valve 40 through the refrigerant supercooling part 23. In this way, in a cooling mode, the refrigerant is prevented from flowing into the receiver tank 22 and the refrigerant supercooling part 23.

FIGS. 8A, 8B, and 8C illustrate a heat exchanger 200 according to a second embodiment. FIG. 8A is a partially omitted perspective view; FIG. 8B is a sectional view taken along line VIIIB-VIIIB in FIG. 8A; and FIG. 8C is a sectional view taken along line VIIIC-VIIIC in FIG. 8A. The heat exchanger 200 according to the second embodiment is an integrated unit of tubes constituting a refrigerant condensing part and tubes constituting a refrigerant supercooling part.

As illustrated in FIG. 8A, the heat exchanger 200 includes a plurality of tubes 210 extending in the vertical direction, radiator fins 220 disposed between the tubes 210, an upper header 230, and a lower header 240. Since the receiver tank 22 is the same as that according to the first embodiment, the same reference numeral is used, and description thereof is not repeated.

As illustrated in FIG. 8C, the tubes 210 each includes a substantially oval cylinder 211 and a partition 212 that divides the space inside the cylinder 211 into two sections. The partition 212 extends vertically from the upper edge to the lower edge of the tube 210 to divide the space inside the tube 210 into two sections. The upper edge 213 of the cylinder 211 has notches 214 at positions corresponding to the partition 212. The lower edge 215 of the cylinder 211 also has notches 216 at positions corresponding to the partition 212 (see FIG. 8B).

The radiator fins 220 are corrugated fins and are disposed entirely along both sides of the tube 210 (see FIG. 8A).

As illustrated in FIG. 8B, the upper header 230 as a substantially convex cross-section with respect to the flow of the refrigerant. The upper header 230 includes a base 231 to which the tube 210 is connected, a cover 232 that covers the top of the base 231, and a partition 233 that partitions the space inside the upper header 230 at a position corresponding to the partition 212.

The base 231 has a substantially plate-like form extending in the same direction as the tubes 210. Through-holes 231a into which the upper edges 213 of tubes 210 are inserted are formed at positions corresponding to the tubes 210. The cover 232 has a convex shape and blocks the upper section of the base 231 and one of the ends on the receiver tank 22 side. The partition 233 extends in the alignment direction of the tube 210. The lower edges of the partition 233 contact a notch 214.

The base 231, the cover 232, and the partition 233 configured in this way are joined together by, for example, welding. The channel cross-section of a channel S10 of a tube 210 disposed leeward of the air-conditioning air A is larger than the channel cross-section of a channel S20 of a tube 210 disposed windward of the air-conditioning air A. In the upper header 230, the channel cross-section of a channel S1 corresponding to the channel S10 is larger than the channel cross-section of a channel S3 corresponding to the channel S20. Similarly, in the lower header 240, the channel cross-section of a channel S2 corresponding to the channel S10 is larger than the channel cross-section of a channel S4 corresponding to the channel S20.

The lower header 240 has a configuration similar to the upper header 230 in that it includes a base 241 having through-holes 241a in which the lower ends of the tubes 210 are inserted, a cover 242 that covers the base 241, and a partition 243. An end surface 240a of the lower header 240 on the receiver tank 22 side is connected to a pipe 22b that communicates with the channel S2 and a pipe 22c that communicates with the channel S4.

In the heat exchanger 200 having such a configuration, in a heating mode, the refrigerant from the compressor 10 passes through the channel S1 of the upper header 230, the channel S10 of the tube 210, and the channel S2 of the lower header 240 to heat the air-conditioning air A. The refrigerant that exchanged heat with the air-conditioning air A is introduced to the receiver tank 22, where liquid and gas is separated, through the pipe 22b and is introduced to the channel S4 of the lower header 240 through the pipe 22c. Then, the refrigerant is introduced to the automatic expansion valve 40 (middle aperture S) through the channels S20 of the tubes 210 and the channel S3 of the upper header 230.

Accordingly, in the heat exchanger 200 according to the second embodiment, the refrigerant condensing part 21 is constituted of the channels S10 of the tubes 210, the radiator fins 220, the channel S1 of the upper header 230, and the channel S2 of the lower header 240. In the second embodiment, the refrigerant supercooling part is constituted of the channels S20 of the tubes 210, the radiator fins 220, the channel S3 of the upper header 230, and the channel S4 of the lower header 240.

As illustrated in FIG. 8B, in the heat exchanger 200 according to the second embodiment having such a configuration, the same air-conditioning air A flows through the overheating region R1 at the refrigerant inlet Q1 of the refrigerant condensing part and the supercooling region R2 at the refrigerant outlet Q2 of the refrigerant supercooling part. Therefore, air-conditioning air A having a similar temperature can be received from other regions, and stable heat exchange without a temperature variation can be achieved.

According to the second embodiment, since the lower header 240 constitutes the channel S2 (branching channel) that branches into the channel through the receiver tank 22 and the channel through the capacitor 30, in a cooling mode, the refrigerant can be prevented from flowing through the receiver tank 22 and the refrigerant supercooling part.

FIGS. 9A and 9B illustrate a heat exchanger 300 according to a third embodiment. FIG. 9A is a longitudinal sectional view; and FIG. 9B is a perspective view of the configuration of a tube. In the heat exchanger 300 according to the third embodiment, tubes 310 constituting a refrigerant condensing part and tubes 320 constituting a refrigerant supercooling part are different types of tubes.

The heat exchanger 300 includes the vertically-extending tubes 310 and 320, radiator fins 330 disposed between the tubes 310 and 320, an upper header 340, and a lower header 350.

As illustrated in FIG. 9B, the channel of a tube 310 is shaped as half a racetrack, and the channel of a tube 320 is shaped as a half oval. The flat wall surface of a tube 310 and the flat wall surface of a tube 320 face each other and a gap 360 is provided therebetween.

The upper header 340 differs from the upper header 230 of the second embodiment in that the base 341 has through-holes 341a and 341b into which the upper ends of the tubes 310 and 320 are respectively inserted. The lower header 350 differs from the lower header 240 of the second embodiment in that the base 351 has through-holes 351a and 351b into which the upper ends of the tubes 310 and 320 are respectively inserted.

In the third embodiment, the tubes 310, the radiator fins 330, the channel S1 of the upper header 340, and the channel S2 of the lower header 350 constitute a refrigerant condensing part. In the third embodiment, the tubes 320, the radiator fins 330, the channel S3 of the upper header 340, and the channel S4 of the lower header 350 constitute a refrigerant supercooling part 23.

The heat exchanger 300 according to the third embodiment having such a configuration, similar to the first and second embodiments, can achieve stable heat exchange without a temperature variation, and in a cooling mode, the refrigerant can be prevented from flowing to the receiver tank 22 and the refrigerant supercooling part.

In the second embodiment, the lower header 240 and the receiver tank 22 are connected with the pipes 22b and 22c. This, however, is not limited, and, as illustrated in FIG. 10A, a block member 400 having a channel 401 connecting the channel S2 of the lower header 240 and the receiver tank 22 and a channel 402 connecting the channel S4 of the lower header 240 and the receiver tank 22 may be used instead. As illustrated in FIG. 10B, the lower header 240 may extend to the bottom of the receiver tank 22; the pipe 22b in the receiver tank 22 may be connected to a communicating hole 245 in the upper surface of the receiver tank 22; and the opening of an outlet of the receiver tank 22 may be connected to a communicating hole 246 in the upper surface. The configuration illustrated in FIGS. 10A and 10B may also be applied to the first and third embodiments.

The tubes 21a, 23a, 210, 310, and 320 in the embodiments of the present invention are not limited to simple cylinders. Instead, for example, as illustrated in FIGS. 11A and 11B, a plurality of channels may be provided inside tubes 210A, 310A, and 320A by embedding a plurality of partitions s. The partition 212 illustrated in FIG. 8C may be used together with the partition s in the tube 210A illustrated in FIG. 11A.

In the headers 230 and 240 illustrated in FIGS. 8A, 8B, and 8C and the headers 340 and 350 illustrated in FIGS. 9A and 9B, the partition and cover may be provided as an integrated unit, as represented by reference numeral 230A in FIG. 11C. As represented by reference numeral 230B in FIG. 11D, the cover, base, and partition may be provided as an integrated unit. As represented by reference numeral 230C in FIG. 11E, a convex header h1 on the refrigerant condensing part side and a convex header h2 on the refrigerant supercooling part side may be connected at their opposing sides, and the contact surface of the headers h1 and h2 may constitute a partition. As represented by reference numeral 230D in FIG. 11F, a sealing member t may be applied at in contact area.

According to the embodiment of the present invention, by extending the tubes vertically and providing a deriving part and an introducing part at the top and bottom of the refrigerant supercooling part, the direction of the refrigerant flowing through the refrigerant condensing part and the direction of the refrigerant flowing through the refrigerant supercooling part becomes opposite, and, as a result, the temperature of the gas received from the heat exchanger becomes uniform.

That is, by the refrigerant flowing from top to bottom in the refrigerant condensing part, the gas is cooled by the refrigerant emitting heat and the condensed refrigerant (liquid refrigerant) accumulates at the bottom, whereas, by the refrigerant (liquid refrigerant) flowing from the introducing part at the bottom to the deriving part at the top, the gas is cooled even more by heat emission of the refrigerant. In this way, the temperature of the refrigerant decreases from the top to the bottom in the refrigerant condensing part and from the bottom to top in the refrigerant supercooling part, a temperature variation along the vertical direction of the heat exchanger can be prevented.

According to the embodiment of the present invention, for example, a refrigerant having a temperature higher than the condensation temperature flows through the overheating region at the refrigerant inlet, and a refrigerant having a temperature lower than the condensation temperature flows through the supercooling region at the refrigerant outlet. Therefore, the refrigerant discharged from the heat exchanger is a gas having an intermediate temperature close to the condensation temperature. By disposing an overheating region and a supercooling region, as described above, gas having no temperature variation in the vertical direction of the heat exchanger can be obtained. In this way, stable heat exchange is possible.

According to the embodiment of the present invention, by providing the branching channel upstream of the gas/liquid separating part, when the refrigerant does not have to flow through the gas/liquid separating part and the refrigerant supercooling part in cooling mode, the refrigerant can be prevented from flowing to the gas/liquid separating part side.

The embodiment of the present invention provides a heat exchanger preventing temperature variation in air received from the heat exchanger.

Obviously, numerous modifications and variations of the present invention are possible in light of the above teachings. It is therefore to be understood that within the scope of the appended claims, the invention may be practiced otherwise than as specifically described herein.

Claims

1. A heat exchanger comprising:

a refrigerant condensing part comprising: tubes in which a refrigerant is to flow to exchange heat between the refrigerant and an external gas to flow outside the tubes; and fins connected to the tubes;

a gas/liquid separating part to separate the refrigerant into gas and liquid; and

a refrigerant supercooling part to exchange heat between the refrigerant and the external gas, the refrigerant supercooling part comprising: a supercooling part inlet from which the refrigerant is to flow into the refrigerant supercooling part; and an outlet from which the refrigerant is to flow out of the refrigerant supercooling part,

wherein the heat exchanger is so constructed that the refrigerant flows through the refrigerant condensing part, the gas/liquid separating part, and the refrigerant supercooling part in this order, and

wherein the heat exchanger is so constructed that the external gas flows around the refrigerant supercooling part and then flows around the refrigerant condensing part.

2. The heat exchanger according to claim 1,

wherein the refrigerant condensing part includes a condensing part inlet from which the refrigerant is to flow into the tubes,

wherein an overheating region is disposed around the condensing part inlet of the refrigerant condensing part, and a supercooling region is disposed around the outlet of the refrigerant supercooling part, and

wherein the heat exchanger is so constructed that the external gas flows through the supercooling region and then, at least part of the external gas flows through the overheating region.

3. The heat exchanger according to claim 1,

wherein the refrigerant condensing part includes a branching channel to branch into a first channel connected to the gas/liquid separating part and a second channel from which the refrigerant is to flow out of the refrigerant condensing part.

4. The heat exchanger according to claim 2,

wherein the refrigerant condensing part includes a branching channel to branch into a first channel connected to the gas/liquid separating part and a second channel from which the refrigerant is to flow out of the refrigerant condensing part.