REFRIGERATION CYCLE APPARATUS
In a refrigeration cycle apparatus, refrigerant circulates in order of a compressor, first and second heat exchangers. The refrigeration cycle apparatus has a refrigerant container, first and second switch units, and a controller. When a first condition meaning that an amount of refrigerant in liquid state stored in the refrigerant container is excessive is satisfied, the controller controls the first switch unit to guide the refrigerant from the compressor to the first heat exchanger through the refrigerant container and controls the second switch unit to guide the refrigerant from the second heat exchanger to the compressor not through the refrigerant container. When the first condition is not satisfied, the controller controls the first switch unit to guide the refrigerant from the compressor to the first heat exchanger not through the refrigerant container and controls the second switch unit to guide the refrigerant from the refrigerant container to the compressor.
This application is a U.S. national stage application of International Patent Application No. PCT/JP2020/000498 filed on Jan. 9, 2020, the disclosure of which is incorporated herein by reference.
TECHNICAL FIELDThe present disclosure relates to a refrigeration cycle apparatus having a function of preventing refrigerant in liquid state (liquid refrigerant) from being sucked into a compressor.
BACKGROUNDA conventional refrigeration cycle apparatus having a function of preventing liquid refrigerant from being sucked into a compressor (liquid back) has been known. For example, Japanese Patent Laying-Open No. 2010-19439 (PTL 1) discloses a refrigeration cycle apparatus capable of switching refrigerant that is to flow into a refrigerant accumulator, depending on the elapsed time from activation of the compressor. In this refrigeration cycle apparatus, refrigerant in the gas-liquid two-phase state of low temperature and low pressure flows into the refrigerant accumulator through low-pressure-side flow path switch means upon activation of the compressor, and refrigerant in gas state (gas refrigerant) separated from the gas-liquid two-phase refrigerant is sucked into the compressor and liquid refrigerant separated therefrom is stored in the refrigerant accumulator.
PATENT LITERATUREPTL 1: Japanese Patent Laying-Open No. 2010-19439
Depending on the time for which the refrigeration cycle apparatus is stopped, a relatively large amount of liquid refrigerant may be stored in the refrigerant container as a result of cooling and resultant liquefaction of the gas refrigerant. If the compressor is activated under this condition, liquid back may occur. Occurrence of the liquid back causes deterioration of the lubrication performance of lubricating oil stored in the compressor, which leads to an increased possibility of failure of the compressor. Moreover, depending on the amount of the lubricating oil stored in the compressor, the performance of the compressor may be deteriorated. For the refrigeration cycle apparatus disclosed in PTL 1, however, no consideration is given to reduction of the amount of liquid refrigerant in the refrigerant container upon activation of the compressor, and no consideration is given to adjustment of the amount of the lubricating oil during operation of the compressor.
SUMMARYThe present disclosure is made to solve the problems as described above, and an object of the present disclosure is to improve the stability of the refrigeration cycle apparatus.
In a refrigeration cycle apparatus according to the present disclosure, refrigerant circulates in order of a compressor, a first heat exchanger, a decompressor, and a second heat exchanger. The refrigeration cycle apparatus has a refrigerant container, a first switch unit, a second switch unit, and a controller. The refrigerant container is configured to store the refrigerant in liquid state. The controller is configured to control the first switch unit and the second switch unit. When a first condition meaning that an amount of the refrigerant in liquid state stored in the refrigerant container is excessive is satisfied, the controller is configured to control the first switch unit to guide the refrigerant from the compressor to the first heat exchanger through the refrigerant container and control the second switch unit to guide the refrigerant from the second heat exchanger to the compressor not through the refrigerant container. When the first condition is not satisfied, the controller is configured to control the first switch unit to guide the refrigerant from the compressor to the first heat exchanger not through the refrigerant container and control the second switch unit to guide the refrigerant from the refrigerant container to the compressor.
In the refrigeration cycle apparatus according to the present disclosure, when the first condition meaning that the amount of refrigerant in liquid state stored in the refrigerant container is excessive is satisfied, refrigerant is guided from the compressor to the first heat exchanger through the refrigerant container and refrigerant is guided from the second heat exchanger to the compressor not through the refrigerant container and, when the first condition is not satisfied, refrigerant is guided from the compressor to the first heat exchanger not through the refrigerant container and refrigerant is guided from the refrigerant container to the compressor. Accordingly, the stability of the refrigeration cycle apparatus can be improved.
Embodiments of the present disclosure are hereinafter described in detail with reference to the drawings. In the drawings, the same or corresponding parts are denoted by the same reference characters, and a description thereof is not herein repeated in principle.
Embodiment 1As shown in
Controller 10 controls the drive frequency of compressor 1 to control the amount of refrigerant discharged per unit time from compressor 1. Controller 10 controls the opening degree of expansion valve 3. Controller 10 controls compressor 1 and expansion valve 3 in such a manner that the degree of subcooling of refrigerant discharged from condenser 2 and the degree of superheat of refrigerant discharged from evaporator 4, for example, meet respective target values.
Controller 10 switches the operation mode of refrigeration cycle apparatus 100. The operation mode includes a refrigerant discharge mode and a normal mode. The refrigerant discharge mode is an operation mode in which the amount of liquid refrigerant stored in accumulator 5 is reduced to increase the amount of refrigerant circulating in refrigeration cycle apparatus 100. The normal mode is an operation mode in which accumulator 5 is caused to store liquid refrigerant and gas refrigerant is caused to flow out from accumulator 5 into compressor 1, to thereby prevent liquid back.
Accumulator 5 includes a port Pt1 (first port), a port Pt2 (second port), a port Pt3 (third port), and a port Pt4 (fourth port). Port Pt2 is formed in the bottom of accumulator 5. Ports Pt1, Pt3, and Pt4 are formed in the top of accumulator 5. The height of port Pt2 is lower than the height of each of port Pt1, port Pt3, and port Pt4. Therefore, flow of liquid refrigerant from port Pt2 can be facilitated, and flow of liquid refrigerant from ports Pt1, Pt3, and Pt4 can be suppressed.
Switch unit 6 includes an on-off valve 61 (first valve), an on-off valve 62 (second valve), and an on-off valve 63 (third valve). On-off valve 61 is connected between a discharge port Ptd of compressor 1 and condenser 2. On-off valve 62 is connected between port Pt1 and a flow path FP1 (first flow path) from discharge port Ptd to on-off valve 61. On-off valve 63 is connected between port Pt2 and a flow path FP2 (second flow path) from on-off valve 61 to condenser 2.
Switch unit 7 includes an on-off valve 71 (fourth valve), an on-off valve 72 (fifth valve), and an on-off valve 73 (sixth valve). On-off valve 71 is connected between evaporator 4 and a suction port Pts of compressor 1. On-off valve 72 is connected between port Pt3 and a flow path FP3 (third flow path) from evaporator 4 to on-off valve 71. On-off valve 73 is connected between port Pt4 and a flow path FP4 (fourth flow path) from on-off valve 71 to suction port Pts.
Input/output unit 13 receives operation from a user, and outputs a result of processing to the user. Input/output unit 13 includes a mouse, a keyboard, a touch panel, a display, and a speaker, for example.
Depending on the time for which refrigeration cycle apparatus 100 is stopped, a relatively large amount of liquid refrigerant may be stored in accumulator 5 as a result of cooling and resultant liquefaction of gas refrigerant. If the normal mode is started under this condition, liquid back may occur. Occurrence of the liquid back causes deterioration of the lubrication performance of refrigeration oil, which leads to an increased possibility of failure of compressor 1.
In refrigeration cycle apparatus 100, therefore, the refrigerant discharge mode is performed when a refrigerant discharge condition (first condition) that the elapsed time from activation of compressor 1 is shorter than a reference time is satisfied, and the normal mode is performed after elapse of the reference time from the activation of compressor 1. During the reference time from activation of compressor 1, liquid refrigerant in accumulator 5 is prevented from being sucked directly into compressor 1. The amount of liquid refrigerant stored in accumulator 5 is reduced during execution of the refrigerant discharge mode, and therefore, the amount of liquid refrigerant stored in accumulator 5, at the time when the normal mode, which is performed after elapse of the reference time, is started, can be reduced to the extent that prevents the liquid refrigerant from flowing out from accumulator 5. Consequently, liquid back in the normal mode can be suppressed.
As shown in
Refrigeration cycle apparatus 100 is described above as the one in which each of switch units 6, 7 has three on-off valves. The configuration of the first switch unit and the second switch unit, however, is not limited to the configuration of switch units 6, 7. The functions of each of the first switch unit and the second switch unit may also be implemented by a four-way valve.
As shown in
Accordingly, the refrigeration cycle apparatuses according to Embodiment 1 and the modification thereof enable the stability to be improved.
Embodiment 2In connection with Embodiment 1, the above description is given of the configuration in which the refrigerant discharge mode is carried out when the refrigerant discharge condition that the elapsed time from activation of the compressor is shorter than a reference time is satisfied, in consideration of the fact that an excessive amount of liquid refrigerant may be stored in the refrigerant container when the compressor is activated. The refrigerant discharge condition is a condition indicative of a high possibility of occurrence of liquid back, and is not limited to the condition that the elapsed time from activation of the compressor is shorter than a reference time. In connection with Embodiment 2, a description is given below of a configuration in which the operation mode is switched between the refrigerant discharge mode and the normal mode, in consideration of the height of the surface of liquid stored in the refrigerant container, or the density of lubricating oil for the compressor in liquid stored in the refrigerant container.
As shown in
As shown in
As shown in
As shown in
In refrigeration cycle apparatus 200A, the normal mode is performed based on the fact that the amount of liquid refrigerant stored in accumulator 5 is relatively small when density D1 is large, even if the height of the liquid surface in accumulator 5 is relatively high. Consequently, liquid back can be suppressed and deficiency of refrigeration oil in compressor 1 can be avoided, and therefore, the reliability of compressor 1 can be improved.
In refrigeration cycle apparatuses 200, 200A, the refrigerant discharge mode may also be performed, as in Embodiment 1, when the elapsed time from activation of compressor 1 is shorter than a reference time. The refrigerant discharge condition may include more than one of the conditions in S101 of
Accordingly, the refrigeration cycle apparatuses according to Embodiment 2 and the modification thereof enable the stability to be improved.
Embodiment 3In connection with Embodiment 3, a description is given below of a configuration in which the operation mode is switched, when the refrigerant discharge condition is not satisfied, between the normal mode and an oil retrieval mode of retrieving lubricating oil stored in the refrigerant container into the compressor, in order to appropriately maintain the amount of lubricating oil stored in the compressor.
As shown in
As shown in
When the oil retrieval condition is satisfied (YES in S303), controller 30 sets the operation mode into the oil retrieval mode in S304, and returns the process back to the main routine. When the oil retrieval condition is not satisfied (NO in S303), controller 30 sets the operation mode into the normal mode in S305, and returns the process back to the main routine.
The oil retrieval condition is not limited to the condition that the amount of change, per sampling time, of the drive frequency of compressor 1 is less than a reference amount. The oil retrieval condition may for example be a condition that the temperature of refrigerant discharged from compressor 1 (discharge temperature) is higher than a reference temperature, a condition that the height of the surface of liquid stored in compressor 1 is higher than a reference height (second reference height), a condition that the density of refrigeration oil in liquid stored in compressor is larger than a reference density (second reference density), or a condition that the height of the surface of liquid stored in accumulator 5 is lower than a reference height (third reference height). The oil retrieval condition may include more than one of these conditions, or include an additional condition(s).
Accordingly, the refrigeration cycle apparatuses according to Embodiment 3 and Modifications 1 to 4 enable the stability to be improved.
The embodiments disclosed herein are also intended to be implemented in an appropriate combination within the range where they are consistent with each other. It should be construed that the embodiments disclosed herein are given by way of illustration in all respects, not by way of limitation. It is intended that the scope of the present disclosure is defined by claims, not by the description above, and encompasses all modifications and variations equivalent in meaning and scope to the claims.
Claims
1. A refrigeration cycle apparatus in which refrigerant circulates in order of a compressor, a first heat exchanger, a decompressor, and a second heat exchanger, the refrigeration cycle apparatus comprising:
- a refrigerant container configured to store the refrigerant in liquid state;
- a first switch unit and a second switch unit; and
- a controller configured to control the first switch unit and the second switch unit,
- when a first condition is satisfied, the controller being configured to control the first switch unit to guide the refrigerant from the compressor to the first heat exchanger through the refrigerant container and to control the second switch unit to guide the refrigerant from the second heat exchanger to the compressor not through the refrigerant container, the first condition meaning that an amount of the refrigerant in liquid state stored in the refrigerant container is excessive,
- when the first condition is not satisfied, the controller being configured to control the first switch unit to guide the refrigerant from the compressor to the first heat exchanger not through the refrigerant container and to control the second switch unit to guide the refrigerant from the refrigerant container to the compressor.
2. The refrigeration cycle apparatus according to claim 1, wherein the first condition includes a condition that an elapsed time from activation of the compressor is shorter than a reference time.
3. The refrigeration cycle apparatus according to claim 1, wherein the first condition includes a condition that a height of a surface of liquid stored in the refrigerant container is higher than a first reference height.
4. The refrigeration cycle apparatus according to claim 1, wherein the first condition includes a condition that a density of lubricating oil for the compressor in liquid stored in the refrigerant container is smaller than a first reference density.
5. The refrigeration cycle apparatus according to claim 1, wherein
- the refrigerant container includes a first port, a second port, a third port, and a fourth port,
- the first switch unit includes a first four-way valve,
- the second switch unit includes a second four-way valve,
- when the first condition is satisfied, the controller is configured to control the first four-way valve to cause a discharge port of the compressor and the first port to communicate with each other and cause the second port and the first heat exchanger to communicate with each other, and control the second four-way valve to cause the third port and the fourth port to communicate with each other and cause the second heat exchanger and a suction port of the compressor to communicate with each other, and
- when the first condition is not satisfied, the controller is configured to control the first four-way valve to cause the discharge port and the first heat exchanger to communicate with each other and cause the first port and the second port to communicate with each other, and control the second four-way valve to cause the third port and the second heat exchanger to communicate with each other and cause the fourth port and the suction port to communicate with each other.
6. The refrigeration cycle apparatus according to claim 1, wherein
- the refrigerant container includes a first port, a second port, a third port, and a fourth port,
- the first switch unit includes a first valve, a second valve, and a third valve,
- the first valve is connected between a discharge port of the compressor and the first heat exchanger,
- the second valve is connected between the first port and a first flow path from the discharge port to the first valve,
- the second switch unit includes a fourth valve, a fifth valve, and a sixth valve,
- the third valve is connected between the second port and a second flow path from the first valve to the first heat exchanger,
- the fourth valve is connected between the second heat exchanger and a suction port of the compressor,
- the fifth valve is connected between the third port and a third flow path from the second heat exchanger to the fourth valve,
- the sixth valve is connected between the fourth port and a fourth flow path from the fourth valve to the suction port,
- when the first condition is satisfied, the controller is configured to close the first valve, open the second valve and the third valve, open the fourth valve, and close the fifth valve and the sixth valve, and
- when the first condition is not satisfied, the controller is configured to open the first valve and open the sixth valve.
7. The refrigeration cycle apparatus according to claim 6, wherein
- when the first condition is not satisfied and a second condition meaning that an amount of lubricating oil stored in the compressor is excessive is satisfied, the controller is configured to open the first valve and the second valve, close the third valve, open the fourth valve, close the fifth valve, and open the sixth valve, and
- when the first condition is not satisfied and the second condition is not satisfied, the controller is configured to open the first valve, close the second valve and the third valve, close the fourth valve, and open the fifth valve and the sixth valve.
8. The refrigeration cycle apparatus according to claim 7, wherein the second condition includes a condition that an amount of change, per unit time, of a drive frequency of the compressor is smaller than a reference amount.
9. The refrigeration cycle apparatus according to claim 7, wherein the second condition includes a condition that a temperature of the refrigerant discharged from the compressor is higher than a reference temperature.
10. The refrigeration cycle apparatus according to claim 7, wherein the second condition includes a condition that a height of a surface of liquid stored in the compressor is higher than a second reference height.
11. The refrigeration cycle apparatus according to claim 7, wherein the second condition includes a condition that a density of lubricating oil for the compressor in liquid stored in the compressor is larger than a second reference density.
12. The refrigeration cycle apparatus according to claim 7, wherein the second condition includes a condition that a height of a surface of liquid stored in the refrigerant container is lower than a third reference height.
13. The refrigeration cycle apparatus according to claim 5, wherein a height of the second port is lower than a height of each of the first port, the third port, and the fourth port.
Type: Application
Filed: Jan 9, 2020
Publication Date: Dec 8, 2022
Inventor: Hiroki ISHIYAMA (Tokyo)
Application Number: 17/777,114