JP2019163867A - Vapor-compression refrigerator - Google Patents

Abstract

To disclose one example of a vapor-compression refrigerator employing a gas injection cycle system, which can restrain refrigeration capacity (heat absorption capacity) occurring at an evaporator from deteriorating.SOLUTION: When a value obtained by subtracting the temperature of a cooling medium from the temperature of a refrigerant flowing into a subcooler 50 becomes equal to or less than a predetermined value, a bypass circuit 51 is communicated. Consequently, it is possible to suppress an increase in a specific enthalpy at an inlet of a second expansion valve 60, and thus it is possible to prevent a gas-liquid two-phase refrigerant from flowing into the second expansion valve 60. Therefore, the refrigerant can be sufficiently decompressed by the second expansion valve 60, and thus it may be possible to generate sufficient refrigeration capacity (heat absorption capacity) in an evaporator 70.SELECTED DRAWING: Figure 1

Description

  The present disclosure relates to a vapor compression refrigerator that moves heat on a low temperature side to a high temperature side.

  For example, the vapor compression refrigerator described in Patent Document 1 includes a compressor, a condenser, an evaporator, a supercooler, a bypass circuit that bypasses the supercooler, a first expansion valve, a second expansion valve, and the like. Yes. The first expansion valve decompresses and expands the refrigerant supplied to the evaporator. The subcooler cools the refrigerant that has flowed out of the condenser. The second expansion valve decompresses the refrigerant that has flowed out of the subcooler or the bypass circuit.

  That is, in the invention described in Patent Document 1, the refrigerant that has been decompressed and expanded by the second expansion valve and the refrigerant that has flowed out of the condenser exchanged heat with the refrigerant that has flowed out of the condenser, thereby flowing out of the condenser. The refrigerant is further cooled.

  Patent Document 2 describes a gas injection cycle type vapor compression refrigerator. The vapor compression refrigerator includes a compressor, a condenser, a first expansion valve, a gas-liquid separator, a supercooler, a second expansion valve, an evaporator, and the like.

  The gas-liquid separator separates the refrigerant that has been decompressed by the first expansion valve into a gas-liquid two-phase state into a gas-phase refrigerant and a liquid-phase refrigerant. The pressure in the gas-liquid separator is an intermediate pressure between the condensation pressure (compressor discharge pressure) and the evaporation pressure (compressor suction pressure). The intermediate-pressure gas-phase refrigerant separated and extracted by the gas-liquid separator is injected (injected) into the compressor in the middle of compression. Thereby, the power consumption of the compressor is reduced.

  The intermediate-pressure liquid phase refrigerant separated and extracted by the gas-liquid separator is cooled by the supercooler to increase the degree of subcooling (subcool), and then reduced to the evaporation pressure by the second expansion valve. Thereby, since the dryness of the refrigerant flowing into the evaporator is reduced, the specific enthalpy difference between the inlet and the outlet of the evaporator can be increased, and a large refrigerating capacity can be obtained.

Japanese Patent No. 6223573 JP 2001-41601 A

  In the gas injection cycle type vapor compression refrigerator, it is desirable that the refrigerant flowing into the second expansion valve is a saturated liquid refrigerant, that is, a dryness-free refrigerant. That is, when the refrigerant flowing into the second expansion valve is in a gas-liquid two-phase state and a gas-phase refrigerant (flash gas) is present in the refrigerant, the refrigerant can be sufficiently decompressed by the second expansion valve. At the same time, the refrigerating capacity (heat absorption capacity) generated in the evaporator is reduced.

  In view of the above points, the present disclosure is an example of a gas injection cycle type vapor compression refrigerator that can suppress a decrease in the refrigerating capacity (heat absorption capacity) generated in the evaporator.

  The vapor compression refrigerator includes, for example, a bypass circuit (51) that bypasses the supercooler (50) and the liquid phase refrigerant that has flowed out of the gas-liquid separator (40) to the second expansion valve (60), and bypass When the value obtained by subtracting the temperature of the cooling medium from the temperature of the refrigerant flowing into the supercooler (50) and the valve (52) for adjusting the communication state of the circuit (51) is equal to or less than a predetermined value, It is desirable to provide a control unit (80) for communicating the bypass circuit (51).

  Thereby, since it becomes possible to suppress the specific enthalpy at the inlet of the second expansion valve (60) from increasing, it is possible to prevent the gas-liquid two-phase refrigerant from flowing into the second expansion valve (60). Therefore, since the refrigerant can be sufficiently decompressed by the second expansion valve (60), it may be possible to generate a sufficient refrigeration capacity (heat absorption capacity) in the evaporator (70).

  Incidentally, the reference numerals in the parentheses above are examples showing the correspondence with the specific configurations described in the embodiments described later, and the present disclosure is limited to the specific configurations indicated in the reference numerals in the parentheses. It is not something.

It is a figure which shows the vapor compression refrigerator which concerns on 1st Embodiment. It is a flowchart which shows control of the vapor compression refrigerator which concerns on 1st Embodiment. It is a figure which shows the vapor compression refrigerator which concerns on 2nd Embodiment. It is a flowchart which shows control of the vapor compression refrigerator which concerns on 2nd Embodiment. It is a flowchart which shows control of the vapor compression refrigerator which concerns on 2nd Embodiment. It is a figure which shows the vapor compression refrigerator which concerns on 3rd Embodiment. It is a flowchart which shows control of the vapor compression refrigerator which concerns on 3rd Embodiment. It is a flowchart which shows control of the vapor compression refrigerator which concerns on 3rd Embodiment.

  The following description shows an example of an embodiment belonging to the technical scope of the present disclosure. In other words, the invention specific items described in the claims are not limited to the specific configurations and structures shown in the following embodiments.

  Hereinafter, embodiments of the present disclosure will be described with reference to the drawings. It should be noted that at least one member or part described with at least a reference numeral is provided, except where “one” or the like is omitted. That is, when there is no notice such as “one”, two or more members may be provided.

(First embodiment)
1. Outline of Vapor Compression Refrigerator In the present embodiment, the present disclosure is applied to a vapor compression refrigerator for an air-cooled package air conditioner. The vapor compression refrigerator is a refrigerator that moves the heat on the low temperature side to the high temperature side by utilizing the endothermic action during refrigerant evaporation.

  Therefore, in the case of absorbing heat from room air, a cooling operation can be performed with a vapor compression refrigerator. When heat is absorbed from the outdoor air, the vapor compression refrigerator 1 can be used for heating operation. A vapor compression refrigerator 1 shown in FIG. 1 has a basic configuration of the vapor compression refrigerator 1 capable of cooling operation.

2. Configuration of Vapor Compression Refrigerator The vapor compression refrigerator 1 includes a compression device 10, a radiator 20, a first expansion valve 30, a gas-liquid separator 40, a supercooler 50, a second expansion valve 60, an evaporator 70, and At least a bypass circuit 51 and the like are provided.

  The compression device 10 sucks and compresses the refrigerant. The compression device 10 is a device that can inject and inject an intermediate-pressure refrigerant in the middle of a compression stroke. Specifically, the compressor 10 includes a first compressor 11 and a second compressor 12.

  The first compressor 11 compresses the low-pressure refrigerant flowing out from the evaporator 70 to a high pressure and discharges the compressed refrigerant toward the radiator 20. The second compressor 12 compresses the intermediate pressure refrigerant to a high pressure and discharges the refrigerant toward the radiator 20.

  The low pressure means the pressure in the evaporator 70. High pressure refers to the pressure in the radiator 20. The intermediate pressure is a pressure between the pressure in the evaporator 70 and the pressure in the radiator 20. Specifically, the intermediate pressure substantially matches the pressure of the refrigerant that has flowed out of the first expansion valve 30.

  The radiator 20 cools the refrigerant discharged from the compressor 10 and releases the heat absorbed by the evaporator 70 to the high temperature side (outdoor air in the present embodiment). In the present embodiment, the discharge pressure of the compression device 10, that is, the refrigerant pressure in the radiator 20, is less than the critical pressure of the refrigerant.

  For this reason, at least a part of the gas-phase refrigerant cooled by the radiator 20 is condensed and liquefied. Therefore, the heat radiator 20 according to the present embodiment functions as a condenser. When the refrigerant pressure in the radiator 20 exceeds the critical pressure, the refrigerant is not condensed in the radiator 20.

  The first expansion valve 30 decompresses and expands the refrigerant that has flowed out of the radiator 20. The refrigerant decompressed by the first expansion valve 30 becomes a gas-liquid two-phase refrigerant. The gas-liquid separator 40 separates the gas-liquid two-phase refrigerant flowing out of the first expansion valve 30 into a liquid-phase refrigerant and a gas-phase refrigerant.

  The intermediate-pressure gas-phase refrigerant separated and extracted by the gas-liquid separator 40 is injected and injected into the compression device 10 during the compression stroke via the injection unit 41. Specifically, the gas-phase refrigerant that has flowed out of the gas-liquid separator 40 is sucked and compressed by the second compressor 12 and then directed to the radiator 20 together with the gas-phase refrigerant compressed by the first compressor 11. Discharged.

  The subcooler 50 cools the intermediate-pressure liquid phase refrigerant separated and extracted by the gas-liquid separator 40. Thereby, the degree of supercooling of the liquid-phase refrigerant increases. The subcooler 50 according to the present embodiment is disposed outside the room and cools the liquid-phase refrigerant with outdoor air. That is, the subcooler 50 cools the liquid-phase refrigerant using the atmosphere (outdoor air) in which the radiator 20 is installed as a cooling medium.

  The second expansion valve 60 decompresses and expands the refrigerant that has flowed out of the subcooler 50. The evaporator 70 absorbs heat from the low temperature side (in this embodiment, indoor air) by evaporating the liquid-phase refrigerant that has flowed out of the second expansion valve 60. The gas-phase refrigerant that has flowed out of the evaporator 70 is supplied to the suction side of the compressor 10 (in the present embodiment, the first compressor 11). The compressor 10 sucks and compresses the gas-phase refrigerant and discharges it to the radiator 20 side.

  In addition, the 2nd expansion valve 60 is arrange | positioned in the position where piping length becomes long enough from the room or the subcooler 50 to the 2nd expansion valve 60. That is, the second expansion valve 60 is disposed at a position where the flash gas may be generated in the refrigerant flowing into the second expansion valve 60. In addition, piping length is long enough means the piping length of 7.5 m or more, for example.

3. Control of vapor compression refrigerator 3.1. Outline of Control The first expansion valve 30 and the second expansion valve 60 are electric expansion valves capable of continuously changing and controlling the throttle opening (decompression degree). The throttle opening of the first expansion valve 30 and the throttle opening of the second expansion valve 60 are controlled by the control unit 80.

  The control unit 80 is configured by a microcomputer having a CPU, a ROM, a RAM, and the like. The control unit 80 controls the first expansion valve 30 and the second expansion valve 60 according to a program stored in advance in a nonvolatile storage unit such as a ROM.

  The controller 80 includes a first pressure sensor S1, a second pressure sensor S2, a third pressure sensor S3, a first temperature sensor S4, a second temperature sensor S5, an outside air temperature sensor S6, and an indoor temperature sensor (not shown). )) Is input.

  The first pressure sensor S <b> 1 detects the refrigerant pressure at the refrigerant inlet of the radiator 20. The second pressure sensor S <b> 2 detects the refrigerant pressure at the refrigerant outlet of the evaporator 70. The third pressure sensor S3 detects the pressure in the gas-liquid separator 40.

  The first temperature sensor S <b> 4 detects the refrigerant temperature at the refrigerant outlet of the radiator 20. The second temperature sensor S <b> 5 detects the refrigerant temperature at the refrigerant outlet of the evaporator 70. The outside air temperature sensor S6 detects the ambient temperature of the radiator 20 and the subcooler 50, that is, the temperature of the outdoor air. The room temperature sensor detects the temperature of the room air before being cooled by the evaporator 70.

<Control of first expansion valve>
The control unit 80 controls the throttle opening degree of the first expansion valve 30 so that the intermediate pressure (in this embodiment, the detection pressure of the third pressure sensor S3) becomes a predetermined target pressure. The target value according to this embodiment is a geometric mean of a high pressure (in this embodiment, a detection pressure of the first pressure sensor S1) and a low pressure (in this embodiment, a detection pressure of the second pressure sensor S2).

<Control of the second expansion valve>
The control unit 80 controls the opening degree of the second expansion valve 60 so that the degree of superheat at the refrigerant outlet of the evaporator 70 is 0 ° C. or higher.

  At this time, the control unit 80 uses the refrigerant pressure at the refrigerant outlet of the evaporator 70 (the detected pressure of the second pressure sensor S2) and the refrigerant temperature at the refrigerant outlet of the evaporator 70 (the detected temperature of the second temperature sensor S5). Then, the state of the refrigerant at the refrigerant outlet of the evaporator 70 is determined.

<Control of the first compressor>
The controller 80 controls the rotation speed of the first compressor 11 so that the degree of supercooling at the refrigerant outlet of the radiator 20 is 0 ° C. or higher.

  At this time, the control unit 80 uses the refrigerant pressure at the refrigerant outlet of the radiator 20 (in this embodiment, the detection pressure of the first pressure sensor S1 substitutes) and the refrigerant temperature at the refrigerant outlet of the radiator 20 (first temperature sensor). The state of the refrigerant at the refrigerant outlet of the radiator 20 is determined using the detected temperature of S4.

<Control of the second compressor>
The control unit 80 controls the rotation speed of the second compressor 12 according to the refrigerating capacity required in the evaporator 70.

  The refrigerating capacity required in the evaporator 70 is determined based on, for example, a value obtained by subtracting the set temperature from the indoor air temperature detected by the indoor temperature sensor (hereinafter referred to as a temperature difference). The set temperature is, for example, a target indoor air temperature or a target air temperature, which is the temperature of air cooled by the evaporator 70 or the like.

  For example, when the temperature difference becomes larger than a predetermined value, the control unit 80 increases the refrigerating capacity generated by the evaporator 70 by increasing the rotational speed of the second compressor 12 from the current rotational speed. For example, when the temperature difference becomes smaller than a predetermined value, the control unit 80 reduces the refrigerating capacity generated by the evaporator 70 by making the rotational speed of the second compressor 12 smaller than the current rotational speed.

<Control of bypass circuit>
The control unit 80 adjusts the communication state of the bypass circuit 51 by controlling the operation of the valve 52. Specifically, the control unit 80 obtains a value obtained by subtracting the temperature of the cooling medium, that is, the temperature of the outdoor air (in this embodiment, the temperature detected by the outdoor air temperature sensor S6) from the refrigerant temperature flowing into the subcooler 50. The valve 52 is actuated so that the bypass circuit 51 is communicated when it becomes equal to or less than a predetermined value.

  The valve 52 according to the present embodiment is configured by a three-way valve that can switch the flow path of the refrigerant that has flowed out of the gas-liquid separator 40. The valve 52 may be provided at any position on the refrigerant outlet side and the refrigerant inlet side of the supercooler 50.

3.2. Details of Control FIG. 2 is an example of a control flow for implementing the outline of the control. In addition, the code | symbol in () in the following description has shown the control step shown by FIG.

  When the vapor compression refrigerator 1 is activated, as shown in FIG. 2, the control unit 80 executes the normal control mode (S1). In the normal control mode, all of the liquid phase refrigerant that has flowed out of the gas-liquid separator 40 passes through the subcooler 50. Control of each of the first expansion valve 30, the second expansion valve 60, the first compressor 11 and the second compressor 12 is as described above.

  Next, the control unit 80 determines whether or not the temperature of the refrigerant flowing into the subcooler 50 is equal to or lower than the temperature of the outdoor air (S3). When it is determined that the temperature of the refrigerant flowing into the subcooler 50 is higher than the temperature of the outdoor air (S3: NO), the control unit 80 continues to execute the normal control mode.

  When it is determined that the temperature of the refrigerant flowing into the subcooler 50 is equal to or lower than the temperature of the outdoor air (S3: YES), the control unit 80 executes the bypass control mode (S5) and then executes S3 again. To do. The bypass control mode is an operation mode in which part or all of the refrigerant flowing out from the gas-liquid separator 40 flows through the bypass circuit 51.

  The control of the first expansion valve 30, the second expansion valve 60, the first compressor 11 and the second compressor 12 in the bypass control mode is the same as in the normal control mode. When the vapor compression refrigerator 1 stops, the bypass circuit 51 is closed.

4). When the controller 80 determines that the temperature of the refrigerant flowing into the subcooler 50 is equal to or lower than the temperature of the outdoor air, the controller 80 executes the bypass control mode. Thereby, even if it is a case where the temperature of outdoor air rises, it can suppress that the specific enthalpy in the inlet_port | entrance of the 2nd expansion valve 60 becomes high.

  Therefore, since the refrigerant in the gas-liquid two-phase state can be prevented from flowing into the second expansion valve 60, the refrigerant can be sufficiently depressurized by the second expansion valve 60, and the evaporator 70 has a sufficient refrigerating capacity. It may be possible to generate (endothermic capacity).

(Second Embodiment)
1. Composition of vapor compression refrigerator <Outline of control>
The vapor compression refrigerator 1 according to the present embodiment can execute the supercooling degree control mode. The supercooling degree control mode is a control mode that is executed when the supercooling degree of the refrigerant flowing into the second expansion valve 60 becomes less than 0 ° C. This is a control mode in which the throttle opening degree of the first expansion valve 30 is controlled so that the cooling degree becomes a liquid phase refrigerant of 0 ° C. or higher.

  As shown in FIG. 3, the control unit 80 according to this embodiment includes detection signals from the fourth pressure sensor S7 and the third temperature sensor S8 in addition to the detection signals from the sensors S1 to S6 according to the first embodiment. Is entered.

  The fourth pressure sensor S7 detects the refrigerant pressure at the refrigerant inlet of the second expansion valve 60. The third temperature sensor S8 detects the refrigerant temperature at the refrigerant inlet of the second expansion valve 60. The control unit 80 determines the state of the refrigerant at the refrigerant inlet of the second expansion valve 60 using the detection value of the fourth pressure sensor S7 and the detection value of the third temperature sensor S8.

  In the supercooling degree control mode, the control unit 80 sets the temperature of the refrigerant flowing into the supercooler 50 to be higher than the ambient temperature (in this embodiment, the temperature detected by the outside air temperature sensor S6). The throttle opening degree of the expansion valve 30 is controlled. That is, the control unit 80 controls the throttle opening of the first expansion valve 30 so that the degree of supercooling of the refrigerant at the refrigerant outlet of the supercooler 50 becomes a predetermined value greater than 0 ° C.

  The “predetermined value greater than 0 ° C.” is a value greater than a value in consideration of the degree of subcooling decrease ΔSC in the refrigerant path from the refrigerant outlet of the supercooler 50 to the refrigerant inlet of the second expansion valve 60. It is.

  That is, the control unit 80 determines that “the degree of supercooling at the refrigerant outlet of the supercooler 50 is equal to or greater than the value obtained by adding the degree of decrease ΔSC to the degree of supercooling at the refrigerant inlet of the second expansion valve 60. That is, the throttle opening degree of one expansion valve 30 is controlled. "

<Details of control>
4 and 5 are examples of a control flow for implementing the above outline. In addition, the code | symbol in () in the following description has shown the control step shown by FIG.4 and FIG.5.

  When the vapor compression refrigerator 1 is activated, the control unit 80 executes the normal control mode (S10). Next, the control unit 80 determines whether or not the degree of supercooling of the refrigerant flowing into the second expansion valve 60 is less than 0 ° C. (S11). When it is determined that the degree of supercooling is not less than 0 ° C. (S11: NO), the controller 80 continues to execute the normal control mode.

  When the control unit 80 determines that the degree of supercooling is less than 0 ° C. (S11: YES), the control unit 80 stores the current outdoor air temperature (hereinafter referred to as “outside air temperature”) in a storage unit such as a RAM ( S12). In the following description, the stored outside air temperature is described as the second outside air temperature.

  Next, after starting the supercooling control mode (S13), the controller 80 determines whether or not the current outside air temperature is equal to or higher than the second outside air temperature (S14). When determining that the current outside air temperature is not equal to or higher than the second outside air temperature (S14: NO), the control unit 80 stops the supercooling control mode and then executes the normal control mode (S10).

  When the control unit 80 determines that the current outside air temperature is equal to or higher than the second outside air temperature (S14: YES), the control unit 80 is a condition for the current operating state of the vapor compression refrigerator 1 to protect the compressor 10. Is judged whether or not (S15).

  The condition deviating from the conditions for protecting the compression device 10 (hereinafter abbreviated as conditions) is, for example, an increase in the outside air temperature resulting in an increase in high pressure and an excessive increase in the load on the compression device 10. State. Specifically, when the state of the vapor compression refrigerator 1 becomes one of the following states, the control unit 80 determines that the condition has deviated.

a) State where the pressure ratio between the intermediate pressure and the condensation pressure is below the set threshold value b) State where the opening of the first expansion valve 30 is above the set threshold value c) State where the intermediate pressure is above the set threshold value d) Condensation pressure ( High pressure) exceeds the set threshold value e) refrigerant temperature discharged from the compressor 10 exceeds the set threshold value When the controller 80 determines that the condition does not deviate (S15: NO), It is determined whether or not the temperature of the refrigerant flowing into the cooler 50 is equal to or lower than the outside air temperature (S19). When it is determined that the temperature of the refrigerant flowing into the subcooler 50 is higher than the outside air temperature (S19: NO), the controller 80 continues to execute the supercooling control mode (S13).

  When it is determined that the temperature of the refrigerant flowing into the subcooler 50 is equal to or lower than the outside air temperature (S19: YES), the control unit 80 stores the current outside air temperature as the first outside air temperature in a storage unit such as a RAM. After that (S16), the bypass control mode is started (S17). The first outside air temperature is usually higher than the second outside air temperature.

  When it is determined that the condition has deviated (S15: YES), the control unit 80 executes S16 and S17. When the bypass control mode is started, the control unit 80 determines whether or not the current outside air temperature is equal to or higher than the first outside air temperature (S18).

  The control of the first expansion valve 30, the second expansion valve 60, the first compressor 11 and the second compressor 12 in the bypass control mode is the same as in the normal control mode. That is, when the bypass control mode is started, the supercooling control mode is stopped.

  When it is determined that the current outside air temperature is equal to or higher than the first outside air temperature (S18: YES), the control unit 80 continues to execute the bypass control mode (S17). When determining that the current outside air temperature is not equal to or higher than the first outside air temperature (S18: NO), the controller 80 shifts to the supercooling control mode (S13).

2. Features of the Vapor Compression Refrigerating Machine According to this Embodiment In the supercooling control mode according to this embodiment, the first is so that the supercooling degree of the refrigerant flowing into the second expansion valve 60 becomes a liquid phase refrigerant of 0 ° C. or higher. The throttle opening degree of the expansion valve 30 is controlled.

  As a result, it is possible to prevent the refrigerant in the gas-liquid two-phase state from flowing into the second expansion valve 60, so that the refrigerant can be sufficiently decompressed by the second expansion valve 60, and sufficient freezing can be performed by the evaporator 70. It may be possible to generate capacity (endothermic capacity).

  The controller 80 controls the throttle opening of the first expansion valve 30 so as to maintain the temperature of the refrigerant flowing into the subcooler 50 at a temperature higher than the ambient temperature. Thereby, it can suppress that the refrigerant | coolant which flows in into the subcooler 50 absorbs heat from atmosphere.

  That is, if the temperature of the refrigerant flowing into the subcooler 50 is lower than the ambient temperature (outdoor air temperature), the refrigerant absorbs heat from the atmosphere, and there is a high possibility that flash gas is generated.

  However, in the present embodiment, the temperature of the refrigerant flowing into the subcooler 50 is maintained at a temperature higher than the ambient temperature (outdoor air temperature), so that the refrigerant does not absorb heat from the atmosphere, and flash gas is generated. Can be suppressed.

  In the present embodiment, it is determined whether or not the operating state of the vapor compression refrigerator 1 has deviated from the conditions for protecting the compressor 10. Thereby, in the said vapor compression refrigerator 1, the high voltage | pressure raises too much and it is suppressed that an excessive load acts on the compression apparatus 10 and the heat radiator 20. FIG.

In addition, the same code | symbol as the above-mentioned embodiment is attached | subjected to the same component requirements as the above-mentioned embodiment. For this reason, in this embodiment, the overlapping description is omitted.
(Third embodiment)
1. Composition of vapor compression refrigerator <Outline of control>
In the vapor compression refrigerator 1 according to the present embodiment, as shown in FIG. 6, a cooler 53 that increases the cooling capacity of the supercooler 50 is provided. The cooler 53 according to the present embodiment is configured by a watering device that sprays a liquid such as water to the supercooler 50.

  The operation of the cooler 53, that is, the watering device is controlled by the control unit 80. In the following description, the control for operating the cooler 53 is described as a watering control mode. After starting the supercooling control mode, the control unit 80 starts the sprinkling control mode when the operating state of the vapor compression refrigeration machine 1 deviates from the conditions for protecting the compressor 10 or in S33 described later.

<Details of control>
7 and 8 are examples of a control flow for implementing the above outline. In addition, the code | symbol in () in the following description has shown the control step shown by FIG.7 and FIG.8.

  When the vapor compression refrigerator 1 is activated, the control unit 80 executes the normal control mode (S20). Next, the control unit 80 determines whether or not the degree of supercooling of the refrigerant flowing into the second expansion valve 60 is less than 0 ° C. (S21). When it is determined that the degree of supercooling is not less than 0 ° C. (S21: NO), the controller 80 continues to execute the normal control mode.

  When determining that the degree of supercooling is less than 0 ° C. (S21: YES), the controller 80 stores the current outside air temperature as the second outside air temperature in a storage unit such as a RAM (S22). After storing the second outside air temperature, the control unit 80 starts the supercooling control mode (S23).

  Next, the control unit 80 determines whether or not the current outside air temperature is equal to or higher than the second outside air temperature (S24). When it is determined that the current outside air temperature is not equal to or higher than the second outside air temperature (S24: NO), the control unit 80 stops the supercooling control mode and then executes the normal control mode (S20).

  When the control unit 80 determines that the current outside air temperature is equal to or higher than the second outside air temperature (S24: YES), the control unit 80 is a condition for the current operating state of the vapor compression refrigerator 1 to protect the compressor 10. Is judged whether or not (S25). This determination is the same as S15.

  When determining that the condition does not deviate (S25: NO), the controller 80 determines whether or not the temperature of the refrigerant flowing into the subcooler 50 is equal to or lower than the outside air temperature (S33). When it is determined that the temperature of the refrigerant flowing into the subcooler 50 is higher than the outside air temperature (S33: NO), the controller 80 continues to execute the supercooling control mode (S23).

  When the control unit 80 determines that the temperature of the refrigerant flowing into the subcooler 50 is equal to or lower than the outside air temperature (S33: YES), the control unit 80 stores the current outside air temperature as the third outside air temperature in the storage unit such as the RAM. (S26), the sprinkling control mode is started (S27).

  The control of the first expansion valve 30, the second expansion valve 60, the first compressor 11 and the second compressor 12 in the watering control mode is the same as in the supercooling control mode. The third outside air temperature is usually higher than the second outside air temperature.

  When it is determined that the condition has deviated (S25: YES), the control unit 80 executes S26 and S27. When the sprinkling control mode is started, the control unit 80 determines whether or not the current outside air temperature is equal to or higher than the third outside air temperature (S28).

  When it is determined that the current outside air temperature is not equal to or higher than the third outside air temperature (S28: NO), the controller 80 continues to execute the supercooling control mode (S23). When it is determined that the current outside air temperature is equal to or higher than the third outside air temperature (S28: YES), the control unit 80 determines whether or not the current operation state of the vapor compression refrigerator 1 has deviated from the condition. Judgment is made (S29). This determination is the same as S25.

  When determining that the condition does not deviate (S29: NO), the controller 80 determines whether or not the temperature of the refrigerant flowing into the subcooler 50 is equal to or lower than the outside air temperature (S34). When it is determined that the temperature of the refrigerant flowing into the subcooler 50 is higher than the outside air temperature (S34: NO), the control unit 80 continues to execute the sprinkling control mode.

  When it is determined that the temperature of the refrigerant flowing into the subcooler 50 is equal to or lower than the outside air temperature (S34: YES), the control unit 80 stores the current outside air temperature in the storage unit such as a RAM as the first outside air temperature. (S30). Next, the controller 80 starts the bypass control mode after stopping the watering control mode (S31). The first outside air temperature is usually higher than the third outside air temperature.

  When the bypass control mode is started, the control unit 80 determines whether or not the current outside air temperature is equal to or higher than the first outside air temperature (S32). When it is determined that the current outside air temperature is equal to or higher than the first outside air temperature (S32: YES), the controller 80 continues to execute the bypass control mode (S31). When it is determined that the current outside air temperature is not equal to or higher than the first outside air temperature (S32: NO), the control unit 80 continues to execute the sprinkling control mode (S27).

2. Features of the Vapor Compression Refrigerator According to the Present Embodiment In the present embodiment, when the operation state of the vapor compression refrigeration machine 1 deviates from the conditions, the sprinkling control mode is executed, so the compressor 10 and the radiator 20 It is suppressed that an excessive load acts on.

  Therefore, the execution time of the supercooling control mode can be longer than that of the vapor compression refrigerator 1 according to the second embodiment. As a result, since the state in which the temperature of the refrigerant flowing into the subcooler 50 is maintained at a temperature higher than the ambient temperature (outdoor air temperature) becomes longer, generation of flash gas can be more effectively suppressed.

In addition, the same code | symbol as the above-mentioned embodiment is attached | subjected to the same component requirements as the above-mentioned embodiment. For this reason, in this embodiment, the overlapping description is omitted.
(Other embodiments)
The valve 52 according to the above-described embodiment is configured by a three-way valve. However, the invention disclosed in this specification is not limited to this. That is, the present invention may be configured such that, for example, the bypass circuit 51 is provided with a two-way valve (open / close valve).

  The supercooler 50 according to the above-described embodiment cooled the liquid-phase refrigerant flowing out of the gas-liquid separator 40 using outdoor air. However, the invention disclosed in this specification is not limited to this. That is, the subcooler 50 according to the present invention may be a heat exchanger that cools the liquid phase refrigerant by exchanging heat between a liquid such as cooling water and the liquid phase refrigerant, for example.

  The cooler 53 according to the above-described third embodiment is configured by a watering device. However, the invention disclosed in this specification is not limited to this. That is, the cooler 53 according to the present invention may be, for example, (1) a heat exchanger that uses the refrigerant flowing out of the evaporator 70, or (2) a heat exchanger that uses the thermoelectric effect.

  The compression apparatus 10 according to the above-described embodiment is configured by two compressors. However, the invention disclosed in this specification is not limited to this. That is, for example, the invention may be configured by the compression device 10 including one compressor having an intermediate pressure refrigerant injection portion. In addition, when the compression apparatus 10 is comprised with two compressors, the connection form of the said two compressors is not ask | required.

  In the above-described embodiment, the vapor compression refrigerator is applied to the air-cooled package air conditioner. However, the invention disclosed in this specification is not limited to this. That is, for example, the present invention can also be applied to a multi-type air conditioner in which the number of indoor units is larger than the number of outdoor units.

  In the multi-type air conditioner provided with a plurality of evaporators 70, the second expansion valve 60 is also a plurality. Therefore, in the second embodiment and the third embodiment, the first expansion valve 30 is opened so that the degree of subcooling of the refrigerant flowing into each second expansion valve 60 becomes a liquid phase refrigerant of 0 ° C. or higher. The degree is controlled.

  The vapor compression refrigerator 1 according to the above-described embodiment is a vapor compression refrigerator that uses cold generated in the evaporator 70 during cooling operation or the like. However, the invention disclosed in this specification is not limited to this. That is, the invention may be a vapor compression refrigerator that uses the heat generated by the radiator 20 such as a heating operation or a water heater.

  The gas-liquid separator 40 in the above-described embodiment is a container-shaped gas-liquid separator that utilizes the density difference between the liquid-phase refrigerant and the gas-phase refrigerant. However, the invention disclosed in this specification is not limited to this.

  That is, the gas-liquid separator 40 is sufficient if it can exhibit the gas-liquid separation function. Therefore, the gas-liquid separator 40 may be, for example, a tubular gas-liquid separator using a refrigerant pipe extending in the horizontal direction.

  Control part 80 concerning the above-mentioned embodiment performed bypass control mode, when the refrigerant temperature which flows into subcooler 50 is larger than the temperature of outdoor air. However, the invention disclosed in this specification is not limited to this.

  That is, the control unit 80 is configured such that a value obtained by subtracting the outdoor temperature from the refrigerant temperature flowing into the subcooler 50 (hereinafter referred to as a temperature difference) is equal to or less than a predetermined value (hereinafter referred to as a predetermined value). It is sufficient to execute the bypass control mode. The predetermined value may be a positive number, a negative number, or 0. Note that the predetermined value according to the above-described embodiment is a negative number.

  The valve 52 according to the above-described embodiment is a switching valve that causes the refrigerant to flow through the bypass circuit 51 or the subcooler 50. However, the invention disclosed in this specification is not limited to this. That is, the present invention may be configured such that the amount of refrigerant flowing through the bypass circuit 51 and the amount of refrigerant flowing through the subcooler 50 are continuously changed according to the temperature difference.

  Furthermore, the present disclosure is not limited to the above-described embodiment as long as it matches the gist of the invention described in the claims. Therefore, you may combine at least 2 embodiment among several embodiment mentioned above.

DESCRIPTION OF SYMBOLS 1 ... Vapor compression refrigerator 10 ... Compressor 11 ... 1st compressor 12 ... 2nd compressor 20 ... Radiator 30 ... 1st expansion valve 40 ... Gas-liquid separator 41 ... Injection part 50 ... Supercooler 51 ... Bypass circuit 52 ... Valve 60 ... Second expansion valve 70 ... Evaporator 80 ... Controller

Claims (1)

In the vapor compression refrigerator that moves the heat on the low temperature side to the high temperature side,
A compression device for compressing the refrigerant;
A radiator that cools the refrigerant discharged from the compressor and releases heat absorbed from the refrigerant to the high temperature side;
A first expansion valve for decompressing and expanding the refrigerant flowing out of the radiator;
A gas-liquid separator that separates the gas-liquid two-phase refrigerant flowing out of the first expansion valve into a liquid-phase refrigerant and a gas-phase refrigerant;
An injection unit for injecting the gas-phase refrigerant flowing out of the gas-liquid separator into the compression device;
A supercooler that cools the liquid-phase refrigerant by exchanging heat between the cooling medium that is a medium other than the refrigerant and the liquid-phase refrigerant that has flowed out of the gas-liquid separator;
A second expansion valve for decompressing and expanding the refrigerant flowing out of the supercooler;
An evaporator that evaporates liquid-phase refrigerant that has flowed out of the second expansion valve and absorbs heat from a low-temperature side, and supplies the evaporated gas-phase refrigerant to the suction side of the compression device;
A bypass circuit that bypasses the supercooler to guide the liquid refrigerant flowing out of the gas-liquid separator to the second expansion valve;
A valve for adjusting the communication state of the bypass circuit;
A control unit for controlling the operation of the valve, wherein when the value obtained by subtracting the temperature of the cooling medium from the refrigerant temperature flowing into the subcooler is equal to or less than a predetermined value, the bypass circuit is A vapor compression refrigeration machine comprising a control unit for communication.

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