WO2022024721A1 - Refrigeration cycle device - Google Patents

Abstract

A refrigeration cycle device (10) has a compressor (11), a condenser (12), a branch part (13a), a first decompression unit (14a), and a first evaporator (15). The refrigeration cycle device further has a second decompression unit (14b), a second evaporator (16), a converging section (13b), and a control unit (70). The control unit has a determination unit (70b) and a decompression control unit (70c). The determination unit circulates a refrigerant to the first evaporator and the second evaporator, and determines whether a liquid backup condition is satisfied in an operation mode in which the refrigerant flow rate circulating through the first evaporator is used as a minimum reference flow rate for suppressing accumulation of refrigerator oil. When the liquid backup condition is determined to be satisfied by the determination unit, the decompression control unit controls the action of the second decompression unit so as to reduce the refrigerant pressure at the outflow opening of the second evaporator to the point at which the refrigerant discharged from the compressor has superheat.

Description

Refrigeration cycle device Cross-reference of related applications

This application is based on Japanese Patent Application No. 2020-126479 filed on July 27, 2020 and Japanese Patent Application No. 2021-69023 filed on April 15, 2021, which are described herein. Use it.

This disclosure relates to a refrigeration cycle device.

Conventionally, in the refrigeration cycle device, in order to protect the compressor, the refrigerating machine oil contained in the refrigerant is suppressed from staying inside the heat exchanger. If the refrigerating machine oil stays in the heat exchanger, the amount of the refrigerating machine oil that circulates substantially in the cycle may decrease, resulting in seizure of the compressor or the like. In this regard, Patent Document 1 protects the compressor by ensuring the flow rate of the refrigerant flowing through the evaporator that exchanges heat with the specific object at least to the extent that the retention of refrigerating machine oil can be suppressed.

Japanese Unexamined Patent Publication No. 2019-129087

Here, in Patent Document 1, when a condition is added to the flow rate of the refrigerant flowing through the heat exchanger as in Patent Document 1, the cooling load in the evaporator and the flow rate of the refrigerant cannot be balanced, and the flow rate of the refrigerant becomes the cooling load. On the other hand, it is expected that it will be excessive. In this case, it is considered that the liquid phase refrigerant that could not be completely evaporated by the evaporator causes a liquid back to flow into the compressor, which causes a failure of the compressor such as liquid compression. In view of this point, it is conceivable to control the operation such as intermittent operation of the compressor in order to adjust the flow rate of the refrigerant as a time average so as to correspond to the cooling load of the evaporator.

On the other hand, there is a configuration having a plurality of evaporators as a refrigeration cycle device. Here, a case where the operation of the compressor is controlled as a method of suppressing the retention of refrigerating machine oil in one of the evaporators and the liquid back from one evaporator to the compressor will be considered. .. In this case, if the operation of the compressor is controlled due to the retention of refrigerating machine oil in one evaporator, the flow rate of the refrigerant to the other evaporator also changes, which affects the cooling performance in the other evaporator. ..

In view of the above points, the present disclosure relates to a refrigerating cycle apparatus having a plurality of evaporators, and the refrigerating cycle capable of suppressing the retention of refrigerating machine oil in the evaporator and liquid backing to the compressor and effectively utilizing the plurality of evaporators. The purpose is to provide the device.

In order to achieve the above object, the refrigeration cycle apparatus according to the first aspect of the present disclosure includes a compressor, a condenser, a branch portion, a first decompression portion, and a first evaporator. Further, the refrigeration cycle apparatus has a second decompression unit, a second evaporator, a confluence unit, and a control unit.

The compressor compresses and discharges the refrigerant including refrigerating machine oil. The condenser condenses the refrigerant discharged from the compressor. The branch portion branches the refrigerant flowing out of the condenser. The first decompression section decompresses the refrigerant flowing out from one of the outlets at the branch section. The first evaporator evaporates the refrigerant flowing out from the first decompression unit.

The second decompression section decompresses the refrigerant that has flowed out from the other end of the outlet at the branch section. The second evaporator evaporates the refrigerant flowing out from the second decompression section. The merging portion merges the refrigerant flowing out of the first evaporator and the refrigerant flowing out of the second evaporator and guides them to the compressor. The control unit controls the operation of the first decompression unit and the second decompression unit.

The control unit has a determination unit and a decompression control unit. The determination unit is in an operation mode in which the refrigerant is circulated to the first evaporator and the second evaporator, and the flow rate of the refrigerant flowing through the first evaporator is equal to or higher than the reference flow rate for suppressing the retention of refrigerating machine oil. , Judge whether the liquid back condition is satisfied. The liquid back condition is a condition relating to the liquid back in which the liquid phase refrigerant flows into the compressor. When the determination unit determines that the liquid back condition is satisfied, the decompression control unit reduces the refrigerant pressure at the outlet of the second evaporator until the refrigerant discharged from the compressor has a degree of superheat. Controls the operation of the second decompression unit.

When the determination unit determines that the liquid back condition is satisfied, the refrigeration cycle device lowers the refrigerant pressure at the outlet of the second evaporator until the refrigerant discharged from the compressor has a degree of superheat. As a result, the refrigerating cycle apparatus distributes the refrigerant to the first evaporator and the second evaporator, and makes the refrigerant flow through the first evaporator equal to or higher than the reference flow rate. Therefore, the refrigerating machine oil in the first evaporator is used. Can suppress the retention of

At the same time, the refrigeration cycle device can increase the dryness of the refrigerant at the confluence by lowering the refrigerant pressure at the outlet of the second evaporator. Therefore, according to the refrigeration cycle device, the state of the refrigerant sucked into the compressor can be changed from the gas phase, so that the occurrence of liquid back to the compressor can be suppressed.

Also, in the Moriel diagram, the slope of the isentropic line shows a smaller value as the pressure decreases. Therefore, the refrigerating cycle device can reduce the refrigerant pressure at the confluence so that the refrigerant discharged from the compressor has a degree of superheat and discharge the gas phase refrigerant from the compressor. It is possible to prevent failures caused by liquid back, such as liquid compression in.

As a result, in the configuration having the first evaporator and the second evaporator, the refrigeration cycle apparatus suppresses the retention of the refrigerating machine oil in the first evaporator and the failure caused by the liquid back to the compressor, and also suppresses the first evaporation. The vessel and the second evaporator can be fully utilized.

Further, the refrigeration cycle apparatus according to the second aspect of the present disclosure includes a compressor, a condenser, a branch portion, a first decompression portion, and a first evaporator. Further, the refrigeration cycle apparatus has a second decompression unit, a second evaporator, a confluence unit, and a control unit.

The compressor compresses and discharges the refrigerant including refrigerating machine oil. The condenser condenses the refrigerant discharged from the compressor. The branch portion branches the refrigerant flowing out of the condenser. The first decompression section decompresses the refrigerant flowing out from one of the outlets at the branch section. The first evaporator evaporates the refrigerant flowing out from the first decompression unit.

The second decompression section decompresses the refrigerant that has flowed out from the other end of the outlet at the branch section. The second evaporator evaporates the refrigerant flowing out from the second decompression section. The merging portion merges the refrigerant flowing out of the first evaporator and the refrigerant flowing out of the second evaporator and guides them to the compressor. The control unit controls the operation of the compressor.

The control unit has a determination unit and a discharge capacity control unit. The determination unit is in an operation mode in which the refrigerant is circulated to the first evaporator and the second evaporator, and the flow rate of the refrigerant flowing through the first evaporator is equal to or higher than the reference flow rate for suppressing the retention of refrigerating machine oil. , Judge whether the liquid back condition is satisfied. The liquid back condition is a condition relating to the liquid back in which the liquid phase refrigerant flows into the compressor. When the determination unit determines that the liquid back condition is satisfied, the discharge capacity control unit reduces the refrigerant pressure at the outlet of the second evaporator until the refrigerant discharged from the compressor has a degree of superheat. , Control the operation of the compressor.

When the determination unit determines that the liquid back condition is satisfied, the refrigeration cycle device reduces the refrigerant pressure at the outlet of the second evaporator until the refrigerant discharged from the compressor has a degree of superheat. Controls the operation of the compressor. As a result, the refrigerating cycle apparatus distributes the refrigerant to the first evaporator and the second evaporator, and makes the refrigerant flow through the first evaporator equal to or higher than the reference flow rate. Therefore, the refrigerating machine oil in the first evaporator is used. Can suppress the retention of

At the same time, the refrigeration cycle device can increase the dryness of the refrigerant at the confluence by lowering the refrigerant pressure at the outlet of the second evaporator. Therefore, according to the refrigeration cycle device, the state of the refrigerant sucked into the compressor can be changed from the gas phase, so that the occurrence of liquid back to the compressor can be suppressed.

Also, in the Moriel diagram, the slope of the isentropic line shows a smaller value as the pressure decreases. Therefore, the refrigerating cycle device can reduce the refrigerant pressure at the confluence so that the refrigerant discharged from the compressor has a degree of superheat and discharge the gas phase refrigerant from the compressor. It is possible to prevent failures caused by liquid back, such as liquid compression in.

As a result, in the configuration having the first evaporator and the second evaporator, the refrigeration cycle apparatus suppresses the retention of the refrigerating machine oil in the first evaporator and the failure caused by the liquid back to the compressor, and also suppresses the first evaporation. The vessel and the second evaporator can be fully utilized.

The above objectives and other objectives, features and advantages of the present disclosure will become clearer from the detailed description below with reference to the accompanying drawings. In the attached drawing
FIG. 1 is a configuration diagram of a vehicle air conditioner including the refrigeration cycle device according to the first embodiment. FIG. 2 is a configuration diagram of the indoor air conditioning unit according to the first embodiment. FIG. 3 is a block diagram showing a control system of the vehicle air conditioner according to the first embodiment. FIG. 4 is a flowchart of the control process for suppressing the liquid back according to the first embodiment. FIG. 5 is an explanatory diagram showing an example of a control table for determining whether or not the liquid back condition in the first embodiment is satisfied. FIG. 6 is an explanatory diagram relating to an example of a criterion for determining whether or not the liquid back condition is satisfied. FIG. 7 is an example of a Moriel diagram when the liquid back condition is satisfied. FIG. 8 is an example of a Moriel diagram when the liquid back suppression control is executed. FIG. 9 is an explanatory diagram showing an example of a control table for determining the target low pressure of the liquid back suppression control in the first embodiment. FIG. 10 is an explanatory diagram showing an example of a control table for determining the target superheat degree of the liquid back suppression control in the second embodiment. FIG. 11 is an explanatory diagram showing an example of a control table for determining the minimum rotation speed of the compressor for liquid back suppression control according to the third embodiment. FIG. 12 is a first modification regarding the configuration of the refrigeration cycle device. FIG. 13 is a second modification regarding the configuration of the refrigeration cycle device.

Hereinafter, a plurality of forms for carrying out the present disclosure will be described with reference to the drawings. In each embodiment, the same reference numerals may be given to the parts corresponding to the matters described in the preceding embodiments, and duplicate description may be omitted. When only a part of the configuration is described in each embodiment, other embodiments described above can be applied to the other parts of the configuration. Not only the combination of the parts that clearly indicate that the combination is possible in each embodiment, but also the partial combination of the embodiments even if the combination is not specified if there is no problem in the combination. Is also possible.

(First Embodiment)
First, the first embodiment in the present disclosure will be described with reference to FIGS. 1 to 3. In the first embodiment, the vehicle air conditioner 1 according to the present disclosure is applied to an electric vehicle in which a driving force for traveling a vehicle is obtained from a traveling electric motor. The vehicle air-conditioning device 1 performs air-conditioning in the vehicle interior, which is an air-conditioning target space, and temperature adjustment of equipment including a battery 42 and the like in an electric vehicle. The vehicle air conditioner 1 can switch between a cooling mode, a heating mode, and a dehumidifying heating mode as an operation mode for air-conditioning the interior of the vehicle.

The refrigeration cycle device 10 in the vehicle air conditioner 1 employs an HFC-based refrigerant (specifically, R134a) as a refrigerant, and a subcritical refrigeration cycle in which the high-pressure side refrigerant pressure does not exceed the critical pressure of the refrigerant. Consists of. It is also possible to use R1234yf or the like as the refrigerant. Refrigerant oil for lubricating the compressor 11 is mixed in the refrigerant. As the refrigerating machine oil, PAG oil (polyalkylene glycol oil) having compatibility with the liquid phase refrigerant is adopted. Some of the refrigerating machine oil circulates in the cycle together with the refrigerant.

Next, a specific configuration of the vehicle air conditioner 1 according to the first embodiment will be described with reference to FIG. The vehicle air conditioner 1 includes a refrigeration cycle device 10, a high temperature side heat medium circuit 20, a low temperature side heat medium circuit 40, a device heat medium circuit 50, an indoor air conditioner unit 60, and a control device 70. There is.

First, the configuration of the refrigeration cycle device 10 in the vehicle air conditioner 1 will be described. The refrigeration cycle device 10 is a steam compression type refrigeration cycle device. The compressor 11 sucks in the refrigerant in the refrigerating cycle device 10, compresses it, and discharges it. The compressor 11 is arranged in the vehicle bonnet.

The compressor 11 is an electric compressor in which a fixed capacity type compression mechanism having a fixed discharge capacity is rotationally driven by an electric motor. The number of revolutions (that is, the refrigerant discharge capacity) of the compressor 11 is controlled by a control signal output from the control device 70 described later.

Then, the inlet side of the refrigerant passage of the heat medium refrigerant heat exchanger 12 is connected to the discharge port of the compressor 11. The heat medium refrigerant heat exchanger 12 is a heat exchanger that radiates heat from the high-pressure refrigerant discharged from the compressor 11 to the heat medium of the high-temperature side heat medium circuit 20 to heat the heat.

The heat medium refrigerant heat exchanger 12 is composed of a so-called subcool type condenser, and has a condensing section 12a, a receiver section 12b, and a supercooling section 12c. The condensing unit 12a is a heat exchange unit that condenses the refrigerant by exchanging heat between the high-pressure refrigerant and the heat medium of the high-temperature side heat medium circuit 20. The receiver unit 12b is a liquid receiving unit that stores the liquid phase refrigerant flowing out of the condensing unit 12a. The supercooling unit 12c is a heat exchange unit that supercools the liquid phase refrigerant by exchanging heat between the liquid phase refrigerant flowing out from the receiver unit 12b and the heat medium of the high temperature side heat medium circuit 20.

As a result, a so-called receiver cycle can be configured, and the high-pressure liquid-phase refrigerant condensed in the condensing section 12a can be stored in the receiver section 12b as a surplus refrigerant in the cycle. Therefore, the refrigerant flowing out of the indoor evaporator 15 can be evaporated until it becomes a vapor phase refrigerant having a degree of superheat. Further, by supercooling the refrigerant in the supercooling unit 12c, the enthalpy difference between the enthalpy of the outlet side refrigerant and the enthalpy of the inlet side refrigerant of the indoor evaporator 15 can be increased.

The heat medium refrigerant heat exchanger 12 corresponds to an example of a condenser. As the heat medium in the high temperature side heat medium circuit 20, a solution containing ethylene glycol, an antifreeze solution, or the like can be adopted.

The refrigerant inlet side of the branch portion 13a is connected to the outlet of the refrigerant passage of the heat medium refrigerant heat exchanger 12. The branch portion 13a branches the flow of the liquid phase refrigerant flowing out of the heat medium refrigerant heat exchanger 12. The branch portion 13a is formed so as to have a three-way joint structure having three refrigerant inflow / outlets communicating with each other. In the branch portion 13a, one of the three inflow outlets is a refrigerant inlet, and the remaining two are refrigerant outlets.

The refrigerant inlet side of the indoor evaporator 15 is connected to one of the refrigerant outlets of the branch portion 13a via the first expansion valve 14a. The refrigerant inlet side of the chiller 16 is connected to the other refrigerant outlet of the branch portion 13a via the second expansion valve 14b.

The first expansion valve 14a is a pressure reducing unit that reduces the pressure of the refrigerant flowing out from one of the refrigerant outlets of the branch portion 13a at least in the cooling mode, and corresponds to an example of the first pressure reducing unit. The first expansion valve 14a is an electric variable throttle mechanism, and has a valve body and an electric actuator. That is, the first expansion valve 14a is configured by a so-called electric expansion valve.

The valve body of the first expansion valve 14a is configured so that the passage opening (in other words, the throttle opening) of the refrigerant passage can be changed. The electric actuator has a stepping motor that changes the throttle opening of the valve body. The operation of the first expansion valve 14a is controlled by a control signal output from the control device 70.

Further, the first expansion valve 14a is composed of a variable throttle mechanism having a fully open function of fully opening the refrigerant passage when the throttle opening is fully opened and a fully closed function of closing the refrigerant passage when the throttle opening is fully closed. Has been done. That is, the first expansion valve 14a can prevent the refrigerant from exerting the depressurizing action by fully opening the refrigerant passage.

Then, the first expansion valve 14a can block the inflow of the refrigerant to the indoor evaporator 15 by blocking the refrigerant passage. That is, the first expansion valve 14a has both a function as a pressure reducing unit for reducing the pressure of the refrigerant and a function as a refrigerant circuit switching unit for switching the refrigerant circuit.

The refrigerant inlet side of the indoor evaporator 15 is connected to the outlet of the first expansion valve 14a. The indoor evaporator 15 is an evaporator that cools the blown air W by exchanging heat between the low-pressure refrigerant decompressed by the first expansion valve 14a and the blown air W to evaporate the low-pressure refrigerant at least in the cooling mode. The indoor evaporator 15 corresponds to an example of the first evaporator. As shown in FIGS. 1 and 2, the indoor evaporator 15 is arranged in the casing 61 of the indoor air conditioning unit 60.

As shown in FIG. 1, a second expansion valve 14b is connected to the other refrigerant outlet at the branch portion 13a. The second expansion valve 14b is a pressure reducing unit that reduces the pressure of the refrigerant flowing out from the other refrigerant outlet of the branch portion 13a at least in the heating mode, and corresponds to an example of the second pressure reducing unit.

Like the first expansion valve 14a, the second expansion valve 14b is an electric variable throttle mechanism, and has a valve body and an electric actuator. That is, the second expansion valve 14b is composed of a so-called electric expansion valve, and has a fully open function and a fully closed function.

That is, the second expansion valve 14b can prevent the refrigerant from exerting the depressurizing action by fully opening the refrigerant passage. Further, the second expansion valve 14b can block the inflow of the refrigerant to the chiller 16 by closing the refrigerant passage. That is, the second expansion valve 14b has both a function as a pressure reducing unit for reducing the pressure of the refrigerant and a function as a refrigerant circuit switching unit for switching the refrigerant circuit.

The refrigerant inlet side of the chiller 16 is connected to the outlet of the second expansion valve 14b. The chiller 16 is a heat exchanger that exchanges heat between the low-pressure refrigerant decompressed by the second expansion valve 14b and the heat medium circulating in the low-temperature side heat medium circuit 40. The chiller 16 corresponds to an example of the second evaporator.

The chiller 16 has a refrigerant passage for circulating the low-pressure refrigerant decompressed by the second expansion valve 14b and a heat medium passage for circulating the heat medium circulating in the low-temperature side heat medium circuit 40. Therefore, the chiller 16 is a heat absorber that evaporates the low-pressure refrigerant and absorbs heat from the heat medium by heat exchange between the low-pressure refrigerant flowing through the refrigerant passage and the heat medium flowing through the heat medium passage.

Then, the inlet side of the evaporation pressure adjusting valve 17 is connected to the refrigerant outlet of the indoor evaporator 15. The evaporation pressure adjusting valve 17 is an evaporation pressure adjusting unit that maintains the refrigerant evaporation pressure in the indoor evaporator 15 at a predetermined reference pressure or higher. The evaporation pressure adjusting valve 17 is configured by a mechanical variable throttle mechanism that increases the valve opening degree as the refrigerant pressure on the outlet side of the indoor evaporator 15 rises.

The evaporation pressure adjusting valve 17 is configured to maintain the refrigerant evaporation temperature in the indoor evaporator 15 at a reference temperature (1 ° C. in the present embodiment) that can suppress frost formation in the indoor evaporator 15. There is.

The other refrigerant inlet side of the merging portion 13b is connected to the outlet of the evaporation pressure adjusting valve 17. As shown in FIG. 1, one refrigerant inlet side of the merging portion 13b is connected to the refrigerant outlet side of the chiller 16.

The merging portion 13b has a three-way joint structure similar to that of the branch portion 13a, and two of the three inflow outlets are used as the refrigerant inlet and the remaining one is used as the refrigerant outlet. The merging portion 13b merges the flow of the refrigerant flowing out from the evaporation pressure adjusting valve 17 and the flow of the refrigerant flowing out from the chiller 16. The suction port side of the compressor 11 is connected to the refrigerant outlet of the merging portion 13b.

Next, the configuration of the high temperature side heat medium circuit 20 in the vehicle air conditioner 1 will be described. The high temperature side heat medium circuit 20 is a heat medium circuit that circulates a heat medium. As the heat medium in the high temperature side heat medium circuit 20, a solution containing ethylene glycol, an antifreeze solution, or the like can be adopted.

The high temperature side heat medium circuit 20 includes a heat medium passage of the heat medium refrigerant heat exchanger 12, a radiator 21, a heater core 22, an electric heater 26, a high temperature side pump 27, a first reserve tank 28, a second reserve tank 29, and circuit switching. The part 30 and the like are arranged.

The radiator 21 is a heat exchanger that exchanges heat between a heat medium heated by a heat medium refrigerant heat exchanger 12 or the like and an outside air OA blown from an outside air fan (not shown), and dissipates the heat of the heat medium to the outside air OA. be.

And the radiator 21 is arranged on the front side in the vehicle bonnet. With the operation of the outside air fan described above, the outside air OA flows from the front side of the vehicle to the rear side and passes through the heat exchange portion of the radiator 21. Further, when the vehicle is traveling, the traveling wind can be applied to the radiator 21 from the front side of the vehicle toward the rear.

The heater core 22 is a heat exchanger that heats the blown air W by exchanging heat between the heat medium heated by the heat medium refrigerant heat exchanger 12 and the blown air W that has passed through the indoor evaporator 15. As shown in FIGS. 1 and 2, the heater core 22 is arranged in the casing 61 of the indoor air conditioning unit 60.

As shown in FIG. 1, in the high temperature side heat medium circuit 20, the radiator 21 and the heater core 22 are connected in parallel to the flow of the heat medium in the high temperature side heat medium circuit 20. That is, the high temperature side heat medium circuit 20 has a common flow path 23 in which both the heat medium circulating via the radiator 21 and the heat medium circulating via the heater core 22 flow in common.

The common flow path 23 includes a heat medium passage of the heat medium refrigerant heat exchanger 12. A heat medium branching portion 24 is arranged on one end side of the common flow path 23. The heat medium branch portion 24 is formed so as to have a three-way joint structure having three inflow / outlets communicating with each other. In the heat medium branching portion 24, one of the three inflow outlets is an inlet, and the remaining two are outlets.

One end of the common flow path 23 is connected to the heat medium inlet side of the heat medium branch portion 24. The inlet side of the radiator 21 is connected to one outlet side of the heat medium branch portion 24 via the first solenoid valve 30a and the second reserve tank 29.

The inlet side of the heater core 22 is connected to the other outlet side of the heat medium branch portion 24 via the second solenoid valve 30b. That is, the heat medium branching portion 24 branches the flow of the heat medium into a flow toward the radiator 21 side and a flow toward the heater core 22 side at the end of the common flow path 23.

A heat medium merging portion 25 is arranged on the other end side of the common flow path 23. The heat medium merging portion 25 is configured to have a three-way joint structure similar to that of the heat medium branching portion 24, and one of the three inflow outlets is an outlet and the other two are inlets. ..

The outlet side of the radiator 21 is connected to one inlet side of the heat medium merging portion 25. The outlet side of the heater core 22 is connected to the other inlet side of the heat medium merging portion 25. The other end of the common flow path 23 is connected to the outlet side of the heat medium merging portion 25.

Therefore, in the high temperature side heat medium circuit 20, the common flow path 23 is connected so that the heat medium flowing out from the radiator 21 and the heat medium flowing out from the heater core 22 can flow in. In the common flow path 23, the heat medium merging portion 25 is located on the most upstream side of the flow of the heat medium. The heat medium branching portion 24 is located on the most downstream side of the flow of the heat medium in the common flow path 23.

As shown in FIG. 1, in addition to the heat medium refrigerant heat exchanger 12, an electric heater 26, a high temperature side pump 27, and a first reserve tank 28 are arranged in the common flow path 23. The electric heater 26 is a heating device that heats a heat medium that generates heat by being supplied with electric power and flows through a common flow path 23.

As the electric heater 26, for example, a PTC heater having a PTC element (that is, a positive characteristic thermistor) can be used. The electric heater 26 can arbitrarily adjust the amount of heat for heating the heat medium by the control voltage output from the control device 70.

The electric heater 26 is arranged on the upstream side of the heat medium branch portion 24 with respect to the flow of the heat medium in the common flow path 23. Specifically, the inlet of the heat medium passage in the electric heater 26 is connected to the outlet side of the heat medium passage in the heat medium refrigerant heat exchanger 12. The outlet side of the heat medium passage in the electric heater 26 is connected to the inlet side of the heat medium branch portion 24. That is, the electric heater 26 is arranged between the heat medium refrigerant heat exchanger 12 and the heat medium branch portion 24 in the common flow path 23.

The high temperature side pump 27 is a heat medium pump that pumps to circulate the heat medium in the high temperature side heat medium circuit 20. The high temperature side pump 27 is an electric pump whose rotation speed (that is, pumping capacity) is controlled by a control voltage output from the control device 70.

As shown in FIG. 1, the suction port of the high temperature side pump 27 is connected to the outlet side of the heat medium merging portion 25 via the first reserve tank 28. The discharge port of the high temperature side pump 27 is connected to the inlet side of the heat medium passage in the heat medium refrigerant heat exchanger 12. Therefore, the high temperature side pump 27 is arranged on the upstream side of the heat medium refrigerant heat exchanger 12 with respect to the flow of the heat medium in the common flow path 23.

The first reserve tank 28 is a heat medium storage unit that stores excess heat medium. By storing the excess heat medium in the first reserve tank 28, it is possible to suppress a decrease in the amount of liquid in the heat medium circulating in the heat medium circuit. Further, the first reserve tank 28 functions as a heat medium supply port for supplying a heat medium when the amount of the heat medium in the heat medium circuit is insufficient.

As described above, in the common flow path 23 of the high temperature side heat medium circuit 20, the heat medium merging portion 25, the first reserve tank 28, the high temperature side pump 27, the heat medium refrigerant heat exchanger 12, and the electric heater 26 follow the flow of the heat medium. , The heat medium branching portion 24 is arranged in this order.

The second reserve tank 29 is a heat medium storage unit for storing excess heat medium, and is arranged on the inlet side of the radiator 21. The second reserve tank 29 also functions as a heat medium supply port for supplying the heat medium when the amount of the heat medium in the heat medium circuit is insufficient.

As shown in FIG. 1, the high temperature side heat medium circuit 20 switches the circuit in the heat medium branch portion 24 to control the flow rate of the heat medium flowing to the radiator 21 side and the flow rate of the heat medium flowing to the heater core 22 side. It has a part 30. Specifically, the circuit switching unit 30 is composed of a first solenoid valve 30a and a second solenoid valve 30b.

The first solenoid valve 30a is a solenoid valve configured so that the opening degree of the heat medium flow path can be adjusted, and is connected to one outlet of the heat medium branch portion 24. The first solenoid valve 30a has a fully closed function and a fully opened function.

Like the first solenoid valve 30a, the second solenoid valve 30b is a solenoid valve configured so that the opening degree of the heat medium flow path can be adjusted, and is arranged at the other outlet of the heat medium branch portion 24. The second solenoid valve 30b has a fully closed function and a fully closed function.

Therefore, when the second solenoid valve 30b is fully closed, the circuit switching unit 30 can allow the heat medium that has passed through the heat medium branching unit 24 to flow into the radiator 21. When the first solenoid valve 30a is fully closed, the circuit switching unit 30 can allow the heat medium that has passed through the heat medium branching unit 24 to flow into the heater core 22. That is, the circuit switching unit 30 can switch the circuit configuration of the high temperature side heat medium circuit 20.

Then, in the vehicle air conditioner 1, a shutter device 31 is arranged on the front side of the radiator 21. The shutter device 31 is configured by rotatably arranging a plurality of blades in the opening of the frame-shaped frame. The plurality of blades rotate in conjunction with each other by the operation of an electric actuator (not shown) to adjust the opening area at the opening of the frame. As a result, the shutter device 31 can adjust the flow rate of the outside air OA passing through the heat exchange unit of the radiator 21, so that the heat exchange capacity of the radiator 21 can be adjusted.

The high temperature side heat medium circuit 20 configured in this way can switch the flow of the heat medium by controlling the circuit switching unit 30. When the second electromagnetic valve 30b is fully closed, the heat medium merging portion 25, the first reserve tank 28, the high temperature side pump 27, the heat medium refrigerant heat exchanger 12, the electric heater 26, the first electromagnetic valve 30a, and the first. 2 The heat medium circulates in the order of the reserve tank 29, the radiator 21, and the heat medium merging portion 25. In this case, the heat of the heat medium of the high temperature side heat medium circuit 20 can be dissipated to the outside air OA, and the frosted radiator 21 can be defrosted by the heat of the heat medium.

On the other hand, when the first electromagnetic valve 30a is fully closed, the heat medium merging portion 25, the first reserve tank 28, the high temperature side pump 27, the heat medium refrigerant heat exchanger 12, the electric heater 26, and the second electromagnetic valve 30b. , The heater core 22, and the heat medium merging portion 25 circulate in this order. In this case, the blown air W can be heated by the heater core 22 by using the heat of the heat medium of the high temperature side heat medium circuit 20, and the heating of the vehicle interior can be realized.

Subsequently, the configuration of the low temperature side heat medium circuit 40 in the vehicle air conditioner 1 will be described. The low temperature side heat medium circuit 40 is a heat medium circuit that circulates a heat medium. As the heat medium of the low temperature side heat medium circuit 40, the same fluid as that of the high temperature side heat medium circuit 20 can be adopted.

The low temperature side heat medium circuit 40 is arranged with a heat medium passage of the chiller 16, a low temperature side pump 41, a battery 42, a charger 43, a low temperature side three-way valve 44, and the like. The discharge port side of the low temperature side pump 41 is connected to the inlet of the heat medium passage in the chiller 16. The low temperature side pump 41 is a heat medium pump that pumps the heat medium of the low temperature side heat medium circuit 40 to the inlet side of the heat medium passage of the chiller 16. The basic configuration of the low temperature side pump 41 is the same as that of the high temperature side pump 27.

One of the inflow outlets of the low temperature side three-way valve 44 is connected to the outlet of the heat medium passage in the chiller 16. The low temperature side three-way valve 44 is composed of an electric three-way flow rate regulating valve having three inflow ports.

The inlet side of the heat medium passage in the battery 42 is connected to another inflow port of the low temperature side three-way valve 44. The battery 42 supplies electric power to various electric devices of the vehicle, and for example, a rechargeable and dischargeable secondary battery (in this embodiment, a lithium ion battery) is adopted. The heat medium passage of the battery 42 is formed in the cover of the battery 42, and by passing the heat medium, the temperature of the battery 42 is adjusted to keep the temperature of the battery 42 within a predetermined temperature range. Can be done.

Then, the inlet side of the heat medium passage in the charger 43 is connected to the outlet side of the heat medium passage of the battery 42. The charger 43 is a charger that charges the battery 42 with electric power. Since the charger 43 generates heat when the battery 42 is charged, the charger 43 can be cooled by the heat medium of the low temperature side heat medium circuit 40.

The outlet side of the heat medium passage in the charger 43 is connected to the suction port of the low temperature side pump 41. Therefore, the low temperature side heat medium circuit 40 can circulate the heat medium by the low temperature side pump 41.

As shown in FIG. 1, yet another inflow port of the low temperature side three-way valve 44 is connected to a heat medium pipe connecting the outlet of the radiator 21 and the heat medium confluence portion 25. Further, the outlet of the heat medium passage in the charger 43 is connected to a heat medium pipe connecting the outlet of the first solenoid valve 30a and the inlet of the second reserve tank 29. That is, in the low temperature side heat medium circuit 40 according to the first embodiment, the battery 42 and the charger 43, the radiator 21 and the second reserve tank 29 are connected in parallel.

Therefore, the low temperature side heat medium circuit 40 can switch the flow of the heat medium in the low temperature side heat medium circuit 40 by controlling the operation of the low temperature side three-way valve 44. For example, the low temperature side three-way valve 44 can communicate the inflow port on the chiller 16 side and the inflow port on the battery 42 side, and can block the remaining inflow port.

In this case, the heat medium in the low temperature side heat medium circuit 40 flows in the order of the low temperature side pump 41, the chiller 16, the low temperature side three-way valve 44, the battery 42, the charger 43, and the low temperature side pump 41, and the low temperature side heat medium circuit 40. To circulate. According to this aspect, since the heat medium cooled by the chiller 16 can be supplied to the battery 42 and the charger 43, the battery 42 and the charger 43 can be cooled.

Further, the low temperature side three-way valve 44 can communicate the three inflow outlets with each other. According to this aspect, the heat medium in the low temperature side heat medium circuit 40 flows in the order of the low temperature side pump 41, the chiller 16, and the low temperature side three-way valve 44, and branches and flows at the low temperature side three-way valve 44. One of the flows of the heat medium flows in the order of the low temperature side three-way valve 44, the battery 42, and the charger 43, and the other flows in the order of the low temperature side three-way valve 44, the radiator 21, and the second reserve tank 29.

Then, the heat medium flowing out from the charger 43 and the heat medium flowing out from the second reserve tank 29 merge and reach the suction port of the low temperature side pump 41. In this case, the low temperature side heat medium circuit 40 can realize cooling of the battery 42 and the charger 43 and heat exchange with the outside air OA in the radiator 21 in parallel.

The vehicle air conditioner 1 can cool the battery 42 and the charger 43 and adjust the temperature by using the low temperature side heat medium circuit 40. Further, the vehicle air conditioner 1 can use the outside air OA as a heat source or dissipate heat to the outside air OA by using the radiator 21.

Next, the configuration of the equipment heat medium circuit 50 in the vehicle air conditioner 1 will be described. The equipment heat medium circuit 50 is a heat medium circuit that circulates a heat medium. As the heat medium of the equipment heat medium circuit 50, the same fluid as the high temperature side heat medium circuit 20 described above can be adopted.

In the heat medium circuit 50 for equipment, a heat medium passage of an in-vehicle device 51, a pump 52 for equipment, a three-way valve 53 for equipment, and the like are arranged. The in-vehicle device 51 is mounted on an electric vehicle and is composed of a device that generates heat during operation. The in-vehicle device 51 includes, for example, an inverter, a motor generator, a transaxle device, and the like.

The inverter is a power conversion unit that converts direct current into alternating current. The motor generator outputs the driving force for traveling by being supplied with electric power, and also generates regenerative electric power at the time of deceleration or the like. The transaxle device is a device that integrates a transmission and a final gear / differential gear (diff gear). The heat medium passage in the in-vehicle device 51 is formed so that each device can be cooled by circulating the heat medium of the device heat medium circuit 50.

Then, the discharge port of the device pump 52 is connected to the inlet side of the heat medium passage in the in-vehicle device 51. The equipment pump 52 is a heat medium pump that pumps the heat medium of the equipment heat medium circuit 50 to the inlet side of the heat medium passage of the in-vehicle equipment 51. The basic configuration of the equipment pump 52 is the same as that of the high temperature side pump 27 and the like.

As shown in FIG. 1, the suction port of the equipment pump 52 is connected to a heat medium pipe connecting the outlet of the first solenoid valve 30a and the inlet of the second reserve tank 29. More specifically, the heat medium pipe extending from the equipment pump 52 is connected between the connection portion with the heat medium pipe extending from the suction port of the low temperature side pump 41 and the inlet of the second reserve tank 29. There is.

Then, one of the inflow outlets of the three-way valve 53 for equipment is connected to the outlet side of the heat medium passage in the in-vehicle device 51. The device three-way valve 53 is composed of an electric three-way flow rate regulating valve having three inflow ports.

Another inflow outlet in the three-way valve 53 for equipment is connected to a heat medium pipe connecting the outlet of the radiator 21 and the heat medium merging portion 25. More specifically, the heat medium pipe extending from the device three-way valve 53 is connected between the outlet of the radiator 21 and the connection portion with the heat medium pipe extending from the low temperature side three-way valve 44.

Therefore, according to the device heat medium circuit 50, the heat medium that has passed through the vehicle-mounted device 51 can be supplied to the radiator 21, and the heat absorbed from the vehicle-mounted device 51 is dissipated to the outside air OA via the heat medium. You can also do it.

Here, a bypass flow path 54 is connected to yet another inflow port of the three-way valve 53 for equipment. The bypass flow path 54 is a heat medium flow path for bypassing the radiator 21 and the second reserve tank 29 with respect to the flow of the heat medium. The other end side of the bypass flow path 54 is connected to the suction port side of the equipment pump 52.

Therefore, the equipment heat medium circuit 50 can switch the flow of the heat medium in the equipment heat medium circuit 50 by controlling the operation of the equipment three-way valve 53. For example, the device three-way valve 53 can communicate the inflow port on the vehicle-mounted device 51 side and the inflow port on the bypass flow path 54 side, and close the remaining inflow port. In this case, the heat medium of the equipment heat medium circuit 50 flows and circulates in the order of the equipment pump 52, the in-vehicle equipment 51, the equipment three-way valve 53, the bypass flow path 54, and the equipment pump 52.

Further, the three-way valve 53 for equipment can block the inflow outlet on the bypass flow path 54 side and allow the remaining two inflow outlets to communicate with each other. In this case, the flow of the heat medium of the equipment heat medium circuit 50 flows and circulates in the order of the equipment pump 52, the in-vehicle equipment 51, the equipment three-way valve 53, the radiator 21, the second reserve tank 29, and the equipment pump 52. ..

According to this aspect, since the heat medium absorbed from the in-vehicle device 51 can be supplied to the radiator 21, the heat generated in the in-vehicle device 51 can be dissipated to the outside air OA. That is, the vehicle air conditioner 1 can cool the in-vehicle device 51 and adjust the temperature by using the device heat medium circuit 50.

Next, the indoor air-conditioning unit 60 constituting the vehicle air-conditioning device 1 will be described with reference to FIG. The indoor air-conditioning unit 60 is a unit for blowing out the blown air W whose temperature has been adjusted by the refrigerating cycle device 10 to an appropriate place in the vehicle interior in the vehicle air-conditioning device 1. The indoor air conditioning unit 60 is arranged inside the instrument panel (that is, the instrument panel) at the front of the vehicle interior.

The indoor air conditioning unit 60 accommodates a blower 62, an indoor evaporator 15, a heater core 22, and the like in an air passage formed inside a casing 61 forming the outer shell thereof. The casing 61 forms an air passage for the blown air W to be blown into the vehicle interior. The casing 61 is made of a resin (specifically, polypropylene) having a certain degree of elasticity and excellent strength.

As shown in FIG. 2, an inside / outside air switching device 63 is arranged on the most upstream side of the blown air flow of the casing 61. The inside / outside air switching device 63 switches and introduces the inside air (vehicle interior air) and the outside air (vehicle interior outside air) into the casing 61.

The inside / outside air switching device 63 continuously adjusts the opening areas of the inside air introduction port for introducing the inside air into the casing 61 and the outside air introduction port for introducing the outside air by the inside / outside air switching door, and adjusts the introduction air volume of the inside air and the outside air. Change the introduction ratio with the introduction air volume. The inside / outside air switching door is driven by an electric actuator for the inside / outside air switching door. The operation of this electric actuator is controlled by a control signal output from the control device 70.

A blower 62 is arranged on the downstream side of the blower air flow of the inside / outside air switching device 63. The blower 62 is composed of an electric blower that drives a centrifugal multi-blade fan with an electric motor. The blower 62 blows the air sucked through the inside / outside air switching device 63 toward the vehicle interior. The rotation speed (that is, the blowing capacity) of the blower 62 is controlled by the control voltage output from the control device 70.

On the downstream side of the blower air flow of the blower 62, the indoor evaporator 15 and the heater core 22 are arranged in this order with respect to the blower air flow. That is, the indoor evaporator 15 is arranged on the upstream side of the blown air flow with respect to the heater core 22.

Further, a cold air bypass passage 65 is formed in the casing 61. The cold air bypass passage 65 is an air passage that allows the blown air W that has passed through the indoor evaporator 15 to bypass the heater core 22 and flow to the downstream side.

The air mix door 64 is arranged on the downstream side of the blown air flow of the indoor evaporator 15 and on the upstream side of the blown air flow of the heater core 22. The air mix door 64 adjusts the air volume ratio between the air volume passing through the heater core 22 and the air volume passing through the cold air bypass passage 65 in the blown air W after passing through the indoor evaporator 15.

The air mix door 64 is driven by an electric actuator for driving the air mix door. The operation of this electric actuator is controlled by a control signal output from the control device 70.

A mixing space 66 is provided on the downstream side of the blown air flow of the heater core 22. In the mixing space 66, the blown air W heated by the heater core 22 and the blown air W that has passed through the cold air bypass passage 65 and has not been heated by the heater core 22 are mixed.

Further, an opening hole for blowing out the blown air (air-conditioned air) mixed in the mixing space 66 into the vehicle interior is arranged at the most downstream portion of the blown air flow of the casing 61. As the opening hole, a face opening hole, a foot opening hole, and a defroster opening hole (none of which are shown) are provided.

The face opening hole is an opening hole for blowing air-conditioned air toward the upper body of the occupant in the passenger compartment. The foot opening hole is an opening hole for blowing air-conditioned air toward the feet of the occupant. The defroster opening hole is an opening hole for blowing air conditioning air toward the inner side surface of the front window glass of the vehicle.

These face opening holes, foot opening holes, and defroster opening holes are the face outlets, foot outlets, and defroster outlets (none of which are shown) provided in the vehicle interior via ducts forming air passages, respectively. )It is connected to the.

Therefore, the temperature of the conditioned air mixed in the mixing space 66 is adjusted by adjusting the air volume ratio between the air volume passing through the heater core 22 and the air volume passing through the cold air bypass passage 65 by the air mix door 64. As a result, the temperature of the blown air (air-conditioned air) blown from each outlet into the vehicle interior is also adjusted.

A face door, a foot door, and a defroster door (none of which are shown) are arranged on the upstream side of the blast air flow of the face opening hole, the foot opening hole, and the defroster opening hole, respectively. The face door adjusts the opening area of the face opening hole. The foot door adjusts the opening area of the foot opening hole. The defroster door adjusts the opening area of the defroster opening hole.

These face doors, foot doors, and defroster doors constitute an outlet mode switching device that switches the outlet from which the air-conditioned air is blown out. The face door, foot door, and defroster door are connected to an electric actuator for driving the outlet mode door via a link mechanism and the like, and are rotated in conjunction with each other. The operation of this electric actuator is controlled by a control signal output from the control device 70.

Next, the control system of the vehicle air conditioner 1 according to the first embodiment will be described with reference to FIG. The control device 70 includes a well-known microcomputer including a CPU, ROM, RAM, and the like, and peripheral circuits thereof.

Then, the control device 70 performs various calculations and processes based on the control program stored in the ROM, and controls the operation of various controlled target devices connected to the output side thereof. The control device 70 corresponds to an example of a control unit.

The equipment to be controlled includes a compressor 11, a first expansion valve 14a, a second expansion valve 14b, an electric heater 26, a high temperature side pump 27, a first solenoid valve 30a, a second solenoid valve 30b, and the like. A shutter device 31 is included. Further, the equipment to be controlled includes a low temperature side pump 41, a low temperature side three-way valve 44, an equipment pump 52, an equipment three-way valve 53, a blower 62 and the like.

As shown in FIG. 3, a sensor group for air conditioning control is connected to the input side of the control device 70. The sensor group for air conditioning control includes internal temperature sensor 72a, outside temperature sensor 72b, solar radiation sensor 72c, high pressure sensor 72d, chiller side pressure sensor 72e, evaporator temperature sensor 72f, confluence temperature sensor 72g, air conditioning air temperature sensor 72h, It includes a battery temperature sensor 72i. The detection signals of these sensors for air conditioning control are input to the control device 70.

The internal air temperature sensor 72a is an internal air temperature detection unit that detects the vehicle interior temperature (internal air temperature) Tr. The outside air temperature sensor 72b is an outside air temperature detection unit that detects the outside air temperature (outside air temperature) Tam. The solar radiation sensor 72c is a solar radiation amount detection unit that detects the solar radiation amount As irradiated to the vehicle interior.

The high pressure sensor 72d is a refrigerant temperature detecting unit that detects the high pressure refrigerant temperature of the refrigerant flow path from the discharge port side of the compressor 11 to the inlet side of the first expansion valve 14a or the second expansion valve 14b. The high pressure sensor 72d is arranged on the outlet side of the refrigerant passage of the heat medium refrigerant heat exchanger 12 and detects the temperature of the refrigerant flowing out from the refrigerant passage of the heat medium refrigerant heat exchanger 12. The high pressure sensor 72d corresponds to an example of the high pressure side temperature detection unit. The chiller-side pressure sensor 72e is a refrigerant pressure detection unit that detects the refrigerant pressure on the outlet side in the refrigerant flow path of the chiller 16. The chiller side pressure sensor 72e corresponds to an example of the refrigerant pressure detection unit.

The evaporator temperature sensor 72f is an evaporator temperature detection unit that detects the refrigerant evaporation temperature (evaporator temperature) Tefien in the indoor evaporator 15. Further, the merging section temperature sensor 72g is a refrigerant temperature detecting section that detects the refrigerant temperature at the merging section 13b of the refrigeration cycle device 10. The conditioned air temperature sensor 72h is an conditioned air temperature detecting unit that detects the blast air temperature TAV blown into the vehicle interior.

The battery temperature sensor 72i is a battery temperature detection unit that detects the battery temperature TB (that is, the temperature of the battery 42). The battery temperature sensor 72i has a plurality of temperature sensors and detects the temperature at a plurality of points of the battery 42. Therefore, the control device 70 can also detect the temperature difference of each part of the battery 42. As the battery temperature TB, the average value of the detection values of a plurality of temperature sensors is adopted.

Then, on the input side of the control device 70, a plurality of heats are used to detect the temperature of the heat medium in each heat medium circuit of the high temperature side heat medium circuit 20, the low temperature side heat medium circuit 40, and the equipment heat medium circuit 50. A medium temperature sensor is connected. The plurality of heat medium temperature sensors include a first heat medium temperature sensor 73a to a fifth heat medium temperature sensor 73e.

The first heat medium temperature sensor 73a is arranged at the inlet portion of the heat medium branch portion 24 to which the common flow path 23 is connected, and detects the temperature of the heat medium flowing out from the common flow path 23. The second heat medium temperature sensor 73b is arranged at the inlet portion of the radiator 21 and detects the temperature of the heat medium passing through the radiator 21. The third heat medium temperature sensor 73c is arranged at the inlet portion of the heater core 22 and detects the temperature of the heat medium passing through the heater core 22.

The fourth heat medium temperature sensor 73d is arranged at the outlet portion of the heat medium passage in the chiller 16 and detects the temperature of the heat medium flowing out of the chiller 16. The fifth heat medium temperature sensor 73e is arranged at the outlet portion of the heat medium passage in the vehicle-mounted device 51, and detects the temperature of the heat medium flowing out from the heat medium passage of the vehicle-mounted device 51.

The vehicle air conditioner 1 refers to the detection results of the first heat medium temperature sensor 73a to the fifth heat medium temperature sensor 73e, and refers to the high temperature side heat medium circuit 20, the low temperature side heat medium circuit 40, and the equipment heat medium circuit 50. Switch the flow of heat medium in. Thereby, the vehicle air conditioner 1 can manage the heat in the vehicle by using the heat medium.

Further, an operation panel 71 arranged near the instrument panel in the front part of the vehicle interior is connected to the input side of the control device 70. A plurality of operation switches are arranged on the operation panel 71. Therefore, operation signals from the plurality of operation switches are input to the control device 70. Various operation switches on the operation panel 71 include an auto switch, a cooling switch, an air volume setting switch, a temperature setting switch, and the like.

The auto switch is operated when setting or canceling the automatic control operation of the vehicle air conditioner 1. The cooling switch is operated when requesting cooling of the passenger compartment. The air volume setting switch is operated when manually setting the air volume of the blower 62. Then, the temperature setting switch is operated when setting the target temperature Tset in the vehicle interior.

In the control device 70, a control unit that controls various control target devices connected to the output side thereof is integrally configured, but a configuration (hardware and software) that controls the operation of each control target device is provided. It constitutes a control unit that controls the operation of each controlled device. For example, in the control device 70, when the operation mode in which the refrigerant is circulated via the indoor evaporator 15 and the chiller 16 (for example, the cooling / cooling mode) is performed, the operation for suppressing the retention of the refrigerating machine oil is controlled. Is a retention suppression control unit 70a.

Further, among the control devices 70, the determination unit 70b is configured to determine the liquid back of the refrigerant to the compressor 11 in the operation mode in which the refrigerant is circulated via the indoor evaporator 15 and the chiller 16. In the control device 70, the decompression control unit 70c controls the operation of the second expansion valve 14b in order to suppress the liquid backing of the refrigerant to the compressor 11. Further, among the control devices 70, the configuration for controlling the refrigerant discharge capacity (that is, the rotation speed) of the compressor 11 in order to suppress the liquid back of the refrigerant to the compressor 11 is the discharge capacity control unit 70d.

Subsequently, the operation of the vehicle air conditioner 1 in the first embodiment will be described. As described above, in the vehicle air conditioner 1 according to the first embodiment, the operation mode can be appropriately switched from the plurality of operation modes. These operation modes are switched by executing a control program stored in advance in the control device 70.

More specifically, in the control program, the target blowing temperature TAO of the blown air to be blown into the vehicle interior is calculated based on the detection signal detected by the sensor group for air conditioning control and the operation signal output from the operation panel 71. do. Then, the operation mode related to the vehicle interior air conditioning is switched based on the target blowout temperature TAO and the detection signal.

Further, the operation mode related to the temperature adjustment for the battery 42 and the in-vehicle device 51 is determined based on the detection signal of the heat medium temperature sensor group and the battery temperature TB. Whether or not to cool the battery 42 is determined based on, for example, whether or not the battery temperature TB exceeds the threshold value, and when the battery temperature TB exceeds the threshold value, an operation mode for cooling the battery 42 is performed. Can be switched to.

Therefore, the plurality of operation modes in the vehicle air conditioner 1 are composed of a combination of an operation mode related to vehicle interior air conditioning and an operation mode related to cooling of the battery 42. The plurality of operation modes include a heating mode, a cooling mode, a dehumidifying heating mode, a heating / cooling mode, a cooling cooling mode, and a dehumidifying / heating / cooling mode.

The heating mode is an operation mode in which the blown air blown into the vehicle interior is heated by the heater core 22 and supplied to the vehicle interior without cooling the battery 42. Further, the cooling mode is an operation mode in which the blown air is cooled by the indoor evaporator 15 and supplied to the vehicle interior without cooling the battery 42. The dehumidifying / heating mode is an operation mode in which the blown air dehumidified by the indoor evaporator 15 is heated by the heater core 22 and supplied to the vehicle interior without cooling the battery 42.

Further, the heating / cooling mode is an operation mode in which the battery 42 is cooled and the blown air is heated by the heater core 22 and supplied to the vehicle interior. Further, the cooling cooling mode is an operation mode in which the battery 42 is cooled and the blown air is cooled by the indoor evaporator 15 and supplied to the vehicle interior. The dehumidifying / heating / cooling mode is an operation mode in which the battery 42 is cooled and the blown air dehumidified by the indoor evaporator 15 is heated by the heater core 22 and supplied to the vehicle interior.

Then, in the plurality of operation modes in the first embodiment, the cooling / cooling mode and the dehumidifying / heating / cooling mode exist as the operation modes in which the refrigerant is circulated to both the indoor evaporator 15 and the chiller 16. In the following description, the operation of the cooling / cooling mode will be described in detail as a specific example of the operation mode in which the refrigerant is circulated to both the indoor evaporator 15 and the chiller 16.

In the cooling / cooling mode, the control device 70 opens the first expansion valve 14a and the second expansion valve 14b at predetermined throttle openings, respectively. Therefore, in the refrigerating cycle device 10 in the cooling / cooling mode, the refrigerant first flows to the compressor 11, the heat medium refrigerant heat exchanger 12, and the branch portion 13a.

The refrigerant flowing out from one side of the branch portion 13a flows to the first expansion valve 14a, the indoor evaporator 15, and the evaporation pressure adjusting valve 17, and the refrigerant flowing out from the other side of the branch portion 13a flows to the second expansion valve 14b. , Flows to the chiller 16. The refrigerant flowing out of the evaporation pressure adjusting valve 17 and the refrigerant flowing out of the chiller 16 merge at the merging portion 13b, and then flow and circulate in the order of the compressor 11.

That is, in the cooling / cooling mode, the refrigerant can be switched to the refrigerant circuit in which the refrigerant flows into the indoor evaporator 15 to cool the blown air W and the refrigerant flows into the chiller 16 to cool the heat medium of the low temperature side heat medium circuit 40. ..

Then, in this cycle configuration, the control device 70 controls the operation of various controlled devices connected to the output side. For example, the control device 70 controls the operation of the compressor 11 so that the refrigerant evaporation temperature Tefien detected by the evaporator temperature sensor 72f becomes the target evaporation temperature TEO. The target evaporation temperature TEO is determined based on the target blowout temperature TAO with reference to the control map for the cooling cooling mode stored in advance in the control device 70.

Specifically, in this control map, the target evaporation temperature TEO is increased as the target outlet temperature TAO increases so that the blown air temperature TAV detected by the air conditioning air temperature sensor 72h approaches the target outlet temperature TAO. Further, the target evaporation temperature TEO is determined to be a value within a range (specifically, 1 ° C. or higher) in which frost formation of the indoor evaporator 15 can be suppressed.

Then, the control device 70 determines the control voltage (blower capacity) of the blower 62 with reference to the control map stored in advance in the control device 70 based on the target blowout temperature TAO. Specifically, in this control map, the amount of air blown by the blower 62 is maximized in the cryogenic region (maximum cooling region) and the cryogenic region (maximum heating region) of the target blowout temperature TAO, and as the temperature approaches the intermediate temperature region. Reduce the amount of air blown. Further, the control device 70 controls the operation of the air mix door 64 so as to fully open the cold air bypass passage 65 and block the ventilation path on the heater core 22 side.

Regarding the high temperature side heat medium circuit 20, the control device 70 controls the operation of the high temperature side pump 27 so as to exert the water pressure feeding capacity in the predetermined cooling cooling mode. Further, the control device 70 controls the circuit switching unit 30 so that the first solenoid valve 30a is fully opened and the second solenoid valve 30b is fully closed.

As a result, the heat medium of the high temperature side heat medium circuit 20 becomes the high temperature side pump 27, the heat medium refrigerant heat exchanger 12, the electric heater 26, the heat medium branch portion 24, the first electromagnetic valve 30a, the second reserve tank 29, and the radiator. It circulates in the order of 21, the heat medium merging portion 25, and the high temperature side pump 27.

As for the low temperature side heat medium circuit 40, the control device 70 controls the operation of the low temperature side pump 41 so as to exert the water pressure feeding capacity in the cooling cooling mode. Further, the control device 70 controls the operation of the low temperature side three-way valve 44 to communicate the inflow outlet on the chiller 16 side and the inflow outlet on the battery 42 side, and close the remaining inflow outlet. As a result, the heat medium in the low temperature side heat medium circuit 40 circulates in the order of the low temperature side pump 41, the chiller 16, the low temperature side three-way valve 44, the battery 42, the charger 43, and the low temperature side pump 41.

In the equipment heat medium circuit 50, the control device 70 controls the operation of the equipment pump 52 so as to exert the water pressure feeding capacity in the predetermined cooling / cooling mode. Further, the control device 70 controls the operation of the three-way valve 53 for the device to communicate the inflow port on the vehicle-mounted device 51 side and the inflow port on the bypass flow path 54 side, and close the remaining inflow port. As a result, the heat medium in the equipment heat medium circuit 50 circulates in the order of the equipment pump 52, the in-vehicle equipment 51, the equipment three-way valve 53, the bypass flow path 54, and the equipment pump 52.

As described above, in the refrigerating cycle device 10 in the cooling / cooling mode, the high-pressure refrigerant discharged from the compressor 11 flows into the heat medium refrigerant heat exchanger 12. In the heat medium refrigerant heat exchanger 12, since the high temperature side pump 27 is operating, the high pressure refrigerant and the heat medium of the high temperature side heat medium circuit 20 exchange heat, the high pressure refrigerant is cooled and condensed, and the heat medium is generated. Be heated.

Then, in the high temperature side heat medium circuit 20, the heat medium heated by the heat medium refrigerant heat exchanger 12 flows into the radiator 21 via the heat medium branch portion 24 and the first solenoid valve 30a. The heat medium flowing into the radiator 21 exchanges heat with the outside air OA to dissipate heat. As a result, the heat medium of the high temperature side heat medium circuit 20 is cooled. The heat medium cooled by the radiator 21 is sucked into the high temperature side pump 27 and again pressure-fed to the heat medium passage of the heat medium refrigerant heat exchanger 12.

On the other hand, the high-pressure refrigerant cooled in the refrigerant passage of the heat medium refrigerant heat exchanger 12 flows into the first expansion valve 14a via the branch portion 13a and is depressurized. The throttle opening of the first expansion valve 14a is basically adjusted so that the degree of superheat of the refrigerant on the outlet side of the indoor evaporator 15 is approximately 3 ° C.

However, the minimum value of the throttle opening of the first expansion valve 14a is limited so that the low-pressure refrigerant decompressed by the first expansion valve 14a suppresses the retention of refrigerating machine oil in the indoor evaporator 15. By limiting the minimum value of the throttle opening of the first expansion valve 14a, the flow rate of the refrigerant flowing through the indoor evaporator 15 is secured to be equal to or higher than the reference flow rate capable of suppressing the retention of refrigerating machine oil.

The low-pressure refrigerant decompressed by the first expansion valve 14a flows into the indoor evaporator 15. The refrigerant flowing into the indoor evaporator 15 absorbs heat from the blown air W blown from the blower 62 and evaporates, and cools the blown air W. The refrigerant flowing out of the indoor evaporator 15 is appropriately depressurized by the evaporation pressure adjusting valve 17, is sucked into the compressor 11 via the merging portion 13b, and is compressed again.

Therefore, in the cooling cooling mode, the interior of the vehicle can be cooled by blowing out the blown air W cooled by the indoor evaporator 15 into the vehicle interior.

Then, the high-pressure refrigerant flowing out from the other side of the branch portion 13a flows into the second expansion valve 14b and is depressurized. The throttle opening of the second expansion valve 14b is usually set so that the degree of superheat of the refrigerant on the outlet side in the refrigerant passage of the chiller 16 approaches the target degree of superheat.

The low-pressure refrigerant decompressed by the second expansion valve 14b flows into the chiller 16 and absorbs heat from the heat medium flowing through the heat medium passage of the chiller 16 and evaporates. As a result, the heat medium of the low temperature side heat medium circuit 40 is cooled. The low-pressure refrigerant flowing out of the chiller 16 is sucked into the compressor 11 via the merging portion 13b and compressed again.

Here, in the low temperature side heat medium circuit 40, the heat medium cooled by the chiller 16 flows into the battery 42 and the charger 43 via the low temperature side three-way valve 44. In the heat medium passage of the battery 42 and the charger 43, the heat medium absorbs heat from the battery 42 and the charger 43 to cool the battery 42 and the charger 43. The heat medium flowing out of the charger 43 is sucked into the low temperature side pump 41 and again pumped to the heat medium passage of the chiller 16.

That is, according to the vehicle air conditioner 1, the heat absorbed when cooling the blown air W and the heat absorbed when cooling the battery 42 and the charger 43 are transferred by the chiller 16 to the heat medium of the low temperature side heat medium circuit 40. It is possible to absorb heat from the low pressure refrigerant.

Then, the vehicle air conditioner 1 draws up the heat absorbed by the chiller 16 and the indoor evaporator 15 in the refrigeration cycle device 10, and dissipates the heat to the heat medium of the high temperature side heat medium circuit 20 by the heat medium refrigerant heat exchanger 12. Then, the heat medium can be heated. The vehicle air conditioner 1 can dissipate the heat of the heat medium of the high temperature side heat medium circuit 20 to the outside air OA by the radiator 21.

In this cooling / cooling mode, the high-temperature side heat medium circuit 20 was configured to dissipate the heat of the heat medium to the outside air OA, but by changing the circuit configuration of the high-temperature side heat medium circuit 20, the circuit configuration can be changed. A circuit configuration of a dehumidifying heating cooling mode can be realized.

Specifically, in the circuit configuration of the dehumidifying / heating / cooling mode, the circuit configurations of the refrigerating cycle device 10, the low temperature side heat medium circuit 40, and the equipment heat medium circuit 50 are the same as those in the cooling / cooling mode. Regarding the high temperature side heat medium circuit 20 in the dehumidifying / heating / cooling mode, the control device 70 controls the circuit switching unit 30 so that the second solenoid valve 30b is fully opened and the first solenoid valve 30a is fully closed. do.

As a result, the heat medium of the high temperature side heat medium circuit 20 becomes the high temperature side pump 27, the heat medium refrigerant heat exchanger 12, the electric heater 26, the heat medium branch portion 24, the second electromagnetic valve 30b, the heater core 22, and the heat medium confluence portion. It circulates in the order of 25 and the high temperature side pump 27. That is, in the dehumidifying / heating / cooling mode, the blown air W dehumidified by the indoor evaporator 15 can be heated by the heater core 22 using the heat of the heat medium as a heat source and supplied to the vehicle interior. Needless to say, in the dehumidifying / heating / cooling mode, the electric heater 26 may be operated as needed.

As described above, in the cooling / cooling mode of the vehicle air conditioner 1, the lower limit of the throttle opening of the first expansion valve 14a is limited in order to suppress the retention of refrigerating machine oil. That is, there is a limit to the minimum value of the refrigerant flow rate flowing through the indoor evaporator 15 that can be adjusted by the first expansion valve 14a.

On the other hand, the cooling load in the indoor evaporator 15 is determined by the temperature of the blown air W to be cooled and the air volume of the blown air W passing through the indoor evaporator 15. Therefore, the cooling load in the indoor evaporator 15 may be too low with respect to the flow rate of the refrigerant flowing through the indoor evaporator 15. In this case, in the indoor evaporator 15, the inflowing refrigerant may not be completely evaporated, and liquid back may occur in which the liquid phase refrigerant remains as it is and flows into the suction port of the compressor 11. When liquid backing occurs, it is assumed that a failure of the compression mechanism due to liquid compression in the compressor 11 will occur.

In the vehicle air conditioner 1 according to the first embodiment, in order to suppress both the retention of the refrigerating machine oil in the indoor evaporator 15 and the failure of the compressor 11 due to the liquid back in the cooling / cooling mode or the like. , The control program is executed.

The control program shown in FIG. 4 is an operation mode in which the refrigerant circulates through the indoor evaporator 15 and the chiller 16 (for example, cooling cooling mode, dehumidifying heating cooling mode), and the throttle opening of the first expansion valve 14a. Executed when the minimum value is limited. That is, when the control device 70 is in an operation mode in which the refrigerant circulates through the indoor evaporator 15 and the chiller 16, the refrigerant flow rate to the indoor evaporator 15 secures a flow rate capable of suppressing the retention of refrigerating machine oil. Then, the control program shown in FIG. 4 is executed.

First, in step S10, it is determined whether or not the liquid back condition indicating a state in which a failure of the compressor 11 due to the liquid back is likely to occur is satisfied. In the first embodiment, with reference to the control map shown in FIG. 5, it is determined whether or not the liquid back condition is satisfied by comparing the cooling load in the indoor evaporator 15 with the reference value defined in the control map. do.

Specifically, the processing content in step S10 will be described. In step S10, first, the cooling load in the indoor evaporator 15 is specified by using the air volume of the blown air passing through the indoor evaporator 15 and the temperature of the blown air passing through the indoor evaporator 15.

The air volume of the blown air passing through the indoor evaporator 15 can be specified, for example, from the control voltage for the blower 62. Further, the temperature of the blown air passing through the indoor evaporator 15 is controlled to be input to, for example, the detection results of the inside air temperature sensor 72a and the outside air temperature sensor 72b and the electric actuator for the inside / outside air switching door in the inside / outside air switching device 63. It can be identified from the signal.

Whether or not the liquid back condition is satisfied by reading the control map shown in FIG. 5 from the ROM of the control device 70 and comparing the cooling load of the indoor evaporator 15 with the reference line KL defined in the control map. Judgment is made.

Specifically, when the cooling load of the indoor evaporator 15 is smaller than the reference line KL defined in the control map, it is highly likely that the compressor 11 will fail due to the liquid back, and the liquid back condition is satisfied. Is determined. On the other hand, when the cooling load of the indoor evaporator 15 is equal to or higher than the reference line KL defined in the control map, it is determined that the liquid back condition is not satisfied because it is unlikely that the compressor 11 will fail due to the liquid back. .. The control device 70 when executing step S10 corresponds to the determination unit 70b.

Here, the reference line KL of the control map shown in FIG. 5 is determined to indicate a case where the refrigerant circulating in the refrigerating cycle device 10 is in a state where the compressor 11 is likely to fail due to liquid backing. Specifically, the reference line KL has a predetermined relationship between the dryness of the refrigerant discharged from the compressor 11 and the amount of refrigerating machine oil remaining inside the compressor 11 (that is, the amount of residual oil). It is defined to be a relationship. The amount of residual oil is calculated from the amount of refrigerating machine oil adhering to the back surface of the scroll arranged inside the compressor 11.

As shown in FIG. 6, there is a relationship between the dryness of the discharged refrigerant and the amount of residual oil, as the dryness of the discharged refrigerant from the compressor 11 increases, the amount of residual oil inside the compressor 11 increases. There is.

Here, in the compressor 11, the minimum amount of oil Vol, which is likely to cause a failure of the compressor 11 due to liquid backing, is experimentally determined based on the specifications such as the configuration of the compression mechanism in the compressor 11. .. Therefore, from the relationship between the dryness of the discharged refrigerant and the residual oil amount shown in FIG. 6, the reference value Kp can be obtained as the dryness of the discharged refrigerant required to secure the minimum oil amount Vol.

That is, the reference line KL according to the first embodiment is the temperature of the intake air for the indoor evaporator 15 and the temperature of the intake air for the indoor evaporator 15 on the premise that the dryness of the discharged refrigerant is the reference value Kp. Shows the relationship.

Subsequently, the Moriel diagram of the refrigerating cycle apparatus 10 when the liquid back condition is satisfied will be described with reference to the drawings. In the Moriel diagram shown in FIG. 7, the point a indicates the state of the refrigerant discharged from the compressor 11, and is located on the left side of the saturated steam line. Therefore, the point a indicates that the refrigerant discharged from the compressor 11 contains the liquid phase refrigerant.

Between points a and b, the high-pressure refrigerant discharged from the compressor 11 is radiated and condensed in the heat medium of the high-temperature side heat medium circuit 20 by the heat medium refrigerant heat exchanger 12. Point b indicates the state of the refrigerant between the outlet side and the branch portion 13a in the refrigerant flow path of the heat medium refrigerant heat exchanger 12, and it can be seen that the refrigerant has a predetermined degree of supercooling.

Between the points b and c, the refrigerant flowing out from one side of the branch portion 13a is depressurized by the first expansion valve 14a. On the other hand, between the points b and e, the refrigerant flowing out from the other side of the branch portion 13a is depressurized by the second expansion valve 14b.

Here, in the refrigerating cycle apparatus 10 when the control program is executed, the lower limit of the throttle opening of the first expansion valve 14a is limited to a refrigerant flow rate capable of suppressing the retention of refrigerating machine oil. .. On the other hand, the throttle opening of the second expansion valve 14b is set so that the degree of superheat of the refrigerant on the outlet side in the refrigerant passage of the chiller 16 approaches the target degree of superheat. Therefore, the decompression amount in the first expansion valve 14a is smaller than the decompression amount in the second expansion valve 14b.

Between the points c and d, the refrigerant flowing out from the first expansion valve 14a exchanges heat with the blown air W in the indoor evaporator 15 and evaporates. At this time, since the cooling load in the indoor evaporator 15 is lower than the flow rate of the refrigerant flowing through the indoor evaporator 15, the refrigerant at the point d is in a gas-liquid two-phase state.

On the other hand, between the points e and f, the refrigerant flowing out from the second expansion valve 14b absorbs heat from the heat medium of the low temperature side heat medium circuit 40 in the chiller 16 and evaporates. The refrigerant flowing out of the chiller 16 is guided to the suction port of the compressor 11 via the merging portion 13b.

Then, between the points d and f, the refrigerant flowing out of the indoor evaporator 15 flows into the evaporation pressure adjusting valve 17 and is depressurized. The refrigerant decompressed by the evaporative pressure adjusting valve 17 merges with the refrigerant flowing out of the chiller 16 at the merging portion 13b, and then is guided to the suction port of the compressor 11. The point f indicates the state of the refrigerant from the confluence portion 13b to the suction port of the compressor 11, and is a gas-liquid two-phase state.

That is, in the Moriel diagram shown in FIG. 7, the compressor 11 sucks in the refrigerant in the gas-liquid two-phase state shown in the point f and discharges it as the refrigerant in the gas-liquid two-phase state shown in the point a. That is, since the refrigerant in the liquid phase state is sucked in, compressed, and discharged in the liquid phase state, it is assumed that the compression mechanism of the compressor 11 fails due to the liquid compression of the refrigerant.

In step S10, it can be said that the cooling load in the indoor evaporator 15 is used to determine whether or not the points a and f in the Moriel diagram of FIG. 7 are in the gas-liquid two-phase state.

When the process proceeds to step S20, it is determined that the liquid back condition is satisfied and there is a possibility that the compressor 11 may fail due to the liquid back, so that the liquid back suppression control is executed. The liquid back suppression control is a control for adjusting the throttle opening of the second expansion valve 14b in order to suppress a failure of the compressor 11 due to the liquid back (for example, a failure of the compression mechanism due to liquid compression). The control device 70 that executes step S20 is a decompression control unit 70c.

Specifically, in the liquid back suppression control in step S20, the control device 70 first makes the control mode of the throttle opening of the second expansion valve 14b different from the normal case (step S30 described later). More specifically, the control device 70 reduces the throttle opening of the second expansion valve 14b until the refrigerant on the discharge port side of the compressor 11 has a degree of superheat. As a result, the amount of decompression in the second expansion valve 14b increases, so that the pressure of the refrigerant flowing through the chiller 16 can be reduced.

Here, with reference to FIG. 8, the state of the refrigerant when the liquid back suppression control is executed will be described. The points a to f in FIG. 8 indicate the same state as the points a to f in the Moriel diagram shown in FIG. 7 described above (that is, a state satisfying the liquid back condition).

As described above, in the liquid back suppression control in step S20, the throttle opening of the second expansion valve 14b is reduced to reduce the pressure of the refrigerant flowing through the chiller 16. Therefore, the point e1 indicating the state of the refrigerant on the refrigerant outlet side of the second expansion valve 14b has a lower pressure than the point e indicating the state of the refrigerant on the refrigerant outlet side of the second expansion valve 14b at the time of determining the liquid back condition. show.

As a result, the point f1 indicating the state of the refrigerant on the outlet side of the refrigerant flow path of the chiller 16 indicates a pressure lower than the point f indicating the state of the refrigerant on the refrigerant outlet side of the chiller 16 at the time of determining the liquid back condition. Further, when the throttle opening degree of the second expansion valve 14b is adjusted by the liquid back suppression control, the amount of decompression in the evaporation pressure adjusting valve 17 increases.

Point f1 in FIG. 8 shows the state of the refrigerant from the confluence portion 13b to the suction port of the compressor 11 when the liquid back suppression control is executed. Here, the saturated steam line in the Moriel diagram shown in FIGS. 7 and 8 is inclined so that the lower the pressure in the low pressure region, the smaller the specific enthalbi.

Therefore, by lowering the refrigerant pressure on the outlet side of the chiller 16 by the liquid back suppression control, the dryness of the refrigerant at the point f1 can be made larger than the dryness of the refrigerant at the point f. In other words, by adjusting the throttle opening of the second expansion valve 14b in the liquid back suppression control, the refrigerant pressure on the outlet side of the chiller 16 is lowered, so that the state of the refrigerant sucked into the compressor 11 is brought closer to the gas phase. Can be.

Further, in the Moriel diagram in FIGS. 7 and 8, the slope of the isentropic line becomes smaller as the pressure becomes smaller. Therefore, in the liquid back suppression control, by lowering the throttle opening degree of the second expansion valve 14b, the specific enthalbi of the refrigerant discharged from the compressor 11 can be increased, and a state having a degree of superheat can be obtained.

That is, by executing the liquid back suppression control, the state of the refrigerant discharged from the compressor 11 can be changed from the point a to the point a1 in the Moriel diagram shown in FIG. 8, and the compressor 11 can be used. The discharged refrigerant can be adjusted to the state of superheated steam. Since the refrigerant at the discharge port of the compressor 11 is superheated steam, the possibility of liquid compression occurring in the compressor 11 can be reduced.

In other words, by adjusting the liquid back suppression control so that the refrigerant discharged from the compressor 11 is in the state of superheated steam, it is possible to suppress the failure of the compressor 11 due to the liquid back.

Further, in the liquid back suppression control in step S20, the second expansion is performed by using the difference between the target low pressure pressure Plo determined according to the cooling load of the indoor evaporator 15 and the detection result detected by the chiller side pressure sensor 72e. The throttle opening of the valve 14b is adjusted.

Specifically, the control device 70 determines the target low pressure pressure Plo as the target value of the refrigerant pressure on the outlet side of the refrigerant flow path of the chiller 16 according to the cooling load in the indoor evaporator 15. The target low pressure pressure Plo corresponds to an example of the target pressure. The cooling load in the indoor evaporator 15 is specified by using the air volume of the blown air passing through the indoor evaporator 15 and the temperature of the blown air passing through the indoor evaporator 15, as in the case of determining the liquid back condition. ..

When determining the target low pressure Plo, the target low pressure Plo is determined using the cooling load in the specified indoor evaporator 15 and the control table for determining the target low pressure Plo. As shown in FIG. 9, in the control table for determining the target low pressure pressure Plo, a plurality of types of target low pressure pressure Plo are associated with the cooling load in the indoor evaporator 15.

There are three types of target low-pressure pressure Plo associated with the control table, Ploa, Plob, and Ploc, and Ploa shows the smallest value. Then, Ploc shows the largest value, and Plob shows a value larger than Ploa and smaller than Ploc. In the control table shown in FIG. 9, the larger the cooling load in the indoor evaporator 15, the larger the target low pressure pressure Plo is associated with.

Then, the control device 70 throttles the second expansion valve 14b by feedback control using the difference between the detection result of the chiller side pressure sensor 72e and the target low pressure pressure Plo determined by using the control table shown in FIG. Adjust the opening. At this time, the throttle opening of the second expansion valve 14b is adjusted so that the value of the refrigerant pressure detected by the chiller side pressure sensor 72e approaches the target low pressure pressure Plo.

As a result, according to the liquid back suppression control in step S20, the throttle opening of the second expansion valve 14b is adjusted according to the cooling load of the indoor evaporator 15, so that the liquid in the compressor 11 caused by the liquid back is adjusted. It is possible to suppress compression and the like, and it is possible to prevent a failure of the compressor 11.

On the other hand, if it is determined in step S10 that the liquid back condition is not satisfied, the control device 70 executes normal control in step S30. In normal control, the control device 70 adjusts the degree of superheat of the refrigerant on the outlet side in the refrigerant passage of the chiller 16 so as to approach the target value. As the target value, a predetermined constant (for example, 5 ° C.) can be adopted.

As described above, in the cooling / cooling mode according to the first embodiment, the refrigerating cycle device 10 limits the minimum value of the throttle opening of the first expansion valve 14a, so that the flow rate of the refrigerant to the indoor evaporator 15 is refrigerated. A flow rate that can suppress the retention of machine oil is secured. As a result, the refrigerating cycle device 10 can suppress the retention of refrigerating machine oil in the indoor evaporator 15.

Further, the refrigerating cycle apparatus 10 adjusts the throttle opening of the second expansion valve 14b by executing the liquid back suppression control in step S20 in the control program shown in FIG. 4, and the refrigerant flowing through the chiller 16 is adjusted. Reduce the pressure. As a result, the dryness of the refrigerant between the confluence portion 13b located downstream of the chiller 16 and the suction port of the compressor 11 can be increased, so that liquid back to the compressor 11 can be suppressed.

Then, the refrigerating cycle apparatus 10 is in a state where the refrigerant at the discharge port of the compressor 11 has a degree of superheat when the pressure of the refrigerant flowing through the chiller 16 is lowered by the liquid back suppression control in step S20. The throttle opening of the second expansion valve 14b is controlled. As a result, the refrigerant discharged from the compressor 11 is in a state of superheated steam, so that the refrigeration cycle device 10 can prevent the liquid compression in the compressor 11, and the failure of the compressor 11 due to the liquid back can be prevented. It can be suppressed.

As a result, according to the refrigeration cycle apparatus 10 according to the first embodiment, by executing the liquid back suppression control in step S20, the retention of the refrigerating machine oil in the indoor evaporator 15 is suppressed, and the compression caused by the liquid back is suppressed. It is possible to prevent the failure of the machine 11.

Then, in step S10, the refrigerating cycle apparatus 10 according to the first embodiment compares the cooling load of the indoor evaporator 15 with the reference set in the control table to determine whether or not the liquid back condition is satisfied. I'm going.

Thereby, in step S10, the magnitude of the possibility that the compressor 11 may fail due to the liquid back can be accurately estimated from the cooling load of the indoor evaporator 15 and the determination accuracy can be improved.

Further, the refrigerating cycle apparatus 10 according to the first embodiment has a target low pressure pressure Plo determined according to the cooling load in the indoor evaporator 15 and a detection value of the chiller side pressure sensor 72e in the liquid back suppression control in step S20. Feedback control is performed using the difference between. Specifically, the control device 70 makes the refrigerant pressure detected by the chiller side pressure sensor 72e approach the target low pressure pressure Plo according to the difference between the target low pressure pressure Plo and the detected value of the chiller side pressure sensor 72e. , Controls the throttle opening of the second expansion valve 14b.

Thereby, in the liquid back suppression control in step S20, the retention of the refrigerating machine oil in the indoor evaporator 15 and the failure of the compressor 11 due to the liquid back are prevented, and at the same time, the cooling performance of the indoor evaporator 15 and the chiller 16 is appropriate. Can be demonstrated.

(Second Embodiment)
Next, a second embodiment different from the first embodiment will be described with reference to FIG. In the second embodiment, the processing contents of steps S10 and S20 in the control program shown in FIG. 4 are different from those in the first embodiment. The basic configurations of the vehicle air conditioner 1, the refrigeration cycle device 10, the high temperature side heat medium circuit 20, the low temperature side heat medium circuit 40, the equipment heat medium circuit 50, the indoor air conditioner unit 60, etc. are the same as those in the first embodiment. Therefore, the explanation will be omitted again.

In step S10 in the second embodiment, it is determined whether or not the liquid back condition is satisfied, as in the first embodiment. Here, in the first embodiment, it is determined whether or not the liquid back condition is satisfied by comparing the cooling load of the indoor evaporator 15 with the standard defined in the control map. Then, the determination is made using the refrigerant temperature on the discharge port side of the compressor 11 detected by the high pressure sensor 72d.

Specifically, in the second embodiment, the control device 70 uses the detection value of the high pressure sensor 72d to back up the liquid depending on whether or not the refrigerant on the discharge port side of the compressor 11 has a degree of superheat. Determine if the condition is met.

When the refrigerant on the discharge port side of the compressor 11 has a degree of superheat, it is considered that there is a low possibility that the compressor 11 will fail due to liquid compression because the discharged refrigerant is in the state of superheated vapor. Therefore, when the discharged refrigerant of the compressor 11 has a degree of superheat, it is determined that the liquid back condition is not satisfied.

On the other hand, when the refrigerant on the discharge port side of the compressor 11 does not have a degree of superheat, the discharged refrigerant is in a gas-liquid two-phase state and contains a liquid-phase refrigerant. Since the liquid phase refrigerant is contained in the state of being discharged from the compression mechanism, it is considered that the compressor 11 may be damaged due to the liquid compression. Therefore, if the discharged refrigerant of the compressor 11 does not have a degree of superheat, it is determined that the liquid back condition is satisfied.

In the second embodiment, since it is determined whether or not the liquid back condition is satisfied by using the measured value detected by the high pressure sensor 72d, it is possible to surely suppress the failure of the compressor 11 due to the liquid back. can.

Subsequently, the liquid back suppression control in step S20 according to the second embodiment will be described. In the liquid back suppression control in the second embodiment, the control device 70 throttles the second expansion valve 14b until the refrigerant on the discharge port side of the compressor 11 has a degree of superheat, as in the first embodiment. Reduce the opening. Since this point is the same as that of the first embodiment, the description thereof will be omitted again.

Here, in the liquid back suppression control according to the first embodiment, the difference between the target low pressure pressure Plo determined according to the cooling load of the indoor evaporator 15 and the detection result detected by the chiller side pressure sensor 72e is used. , The throttle opening of the second expansion valve 14b is adjusted.

On the other hand, in the liquid back suppression control according to the second embodiment, the target superheat degree determined according to the cooling load of the indoor evaporator 15 and the refrigerant temperature on the discharge side of the compressor 11 detected by the high pressure sensor 72d. The difference is used to adjust the throttle opening of the second expansion valve 14b.

Specifically, the control device 70 determines the target superheat degree Sho as the target value of the refrigerant temperature on the discharge port side of the compressor 11 according to the cooling load in the indoor evaporator 15. The cooling load in the indoor evaporator 15 is specified by the same method as that of the first embodiment described above.

When determining the target superheat degree Sho, the target superheat degree Sho is determined using the cooling load in the specified indoor evaporator 15 and the control table for determining the target superheat degree Sho. As shown in FIG. 10, in the control table for determining the target superheat degree Sho, a plurality of types of target superheat degree Sho are associated with the cooling load in the indoor evaporator 15.

There are three types of target superheat degree Sho associated with the control table, Shoa, Shob, and Shoc, and Shoa shows the smallest value. And, Shoc shows the largest value, Shob shows a larger value than Shoa, and shows a smaller value than Shoc. In the control table shown in FIG. 10, the larger the cooling load in the indoor evaporator 15, the larger the target superheat degree Sho is associated with.

Then, the control device 70 controls the throttle opening of the second expansion valve 14b by feedback control using the difference between the detection result of the high pressure sensor 72d and the target superheat degree Sho determined by using the control table shown in FIG. To adjust. At this time, the throttle opening of the second expansion valve 14b is adjusted so that the value of the superheat degree of the discharged refrigerant of the compressor 11 detected by the high pressure sensor 72d approaches the target superheat degree Sho.

In the second embodiment, feedback control regarding the throttle opening of the second expansion valve 14b is performed so as to approach the target superheat degree Sho determined by using the measured value detected by the high pressure sensor 72d. Therefore, the refrigeration cycle device 10 can appropriately adjust the cooling capacity of the indoor evaporator 15 and the chiller 16 according to the current situation.

As described above, the refrigerating cycle apparatus 10 according to the second embodiment is the same as the first embodiment described above even when the control mode is changed to the one using the degree of superheat of the refrigerant on the discharge port side of the compressor 11. The action and effect produced from the configuration and operation of the above can be obtained in the same manner as in the first embodiment.

Further, in the second embodiment, the result of actually detecting the state of the discharged refrigerant of the compressor 11 is used to determine the liquid back condition and control the throttle opening of the second expansion valve 14b. Therefore, when the failure of the compressor 11 due to the liquid back is likely to actually occur, the failure of the compressor 11 can be reliably suppressed.

(Third Embodiment)
Subsequently, a third embodiment different from the above-described embodiment will be described with reference to FIG. In the third embodiment, the processing contents of steps S10 and S20 in the control program shown in FIG. 4 are different from the above-described embodiment. The basic configurations of the vehicle air conditioner 1, the refrigeration cycle device 10, the high temperature side heat medium circuit 20, the low temperature side heat medium circuit 40, the equipment heat medium circuit 50, the indoor air conditioner unit 60, etc. are the same as those in the above-described embodiment. Therefore, the explanation will be omitted again.

Also in the third embodiment, the control device 70 executes the control program shown in FIG. 4 in the operation mode in which the refrigerant circulates through the indoor evaporator 15 and the chiller 16. In step S10 of the third embodiment, the control device 70 determines whether or not the required refrigerant flow rate in the indoor evaporator 15 is equal to or less than the reference flow rate for suppressing the retention of refrigerating machine oil as a liquid back condition.

The required refrigerant flow rate means the refrigerant flow rate required for the indoor evaporator 15 to dehumidify from the blown air, and the operation of the inside air temperature sensor 72a, the outside air temperature sensor 72b, the evaporator temperature sensor 72f, and the inside / outside air switching device 63. It can be estimated using the mode, the amount of air blown by the blower 62, and the like. The reference flow rate is defined as the refrigerant flow rate required for the residual oil amount of the compressor 11 to secure the minimum oil amount Vol.

When the required refrigerant flow rate is equal to or less than the reference flow rate, it is determined that the amount of refrigerant liquid back to the compressor 11 is excessive, and the process proceeds to step S20. On the other hand, if the required refrigerant flow rate is larger than the reference flow rate, the process proceeds to step S30. Since the processing content of step S30 is the same as that of the above-described embodiment, the description thereof will be omitted again.

In step S20 according to the third embodiment, the refrigerant discharge capacity of the compressor 11 is controlled as a liquid back suppression control for suppressing a failure of the compressor 11 due to the liquid back (for example, a failure of the compression mechanism due to liquid compression). Control is performed to adjust the lower limit value (that is, the minimum rotation speed). The control device 70 that executes step S20 constitutes the discharge capacity control unit 70d according to the third embodiment.

By setting the minimum rotation speed of the compressor 11, it means that the state does not become lower than the minimum rotation speed in controlling the refrigerant discharge capacity of the compressor 11. In other words, in controlling the refrigerant discharge capacity of the compressor 11, if the refrigerant discharge capacity is larger than the minimum rotation speed, it can be appropriately changed according to the required cooling capacity and the like.

Specifically, in the liquid back suppression control in step S20, the control device 70 uses the lower refrigerant pressure of the refrigerant pressure on the outlet side of the indoor evaporator 15 and the refrigerant pressure on the outlet side of the chiller 16. Set the minimum rotation speed of 11.

Here, in the refrigerating cycle device 10 of the vehicle air conditioner 1, the indoor evaporator 15 and the chiller 16 are connected in parallel to the flow of the refrigerant flowing out from the heat medium refrigerant heat exchanger 12. Further, an evaporation pressure adjusting valve 17 is arranged on the refrigerant outlet side of the indoor evaporator 15. Therefore, in the third embodiment, the lower refrigerant pressure of the refrigerant pressure on the outlet side of the indoor evaporator 15 and the refrigerant pressure on the outlet side of the chiller 16 becomes the refrigerant pressure on the outlet side of the chiller 16 and the chiller side pressure. It can be detected by the sensor 72e.

Therefore, in step S20 according to the third embodiment, the control device 70 refers to the refrigerant pressure on the outlet side of the chiller 16 detected by the chiller side pressure sensor 72e and the control map shown in FIG. Set the minimum rotation speed of 11. In the control map shown in FIG. 11, the minimum rotation speed of the compressor 11 is set so that the dryness of the refrigerant discharged from the compressor 11 is equal to or higher than the reference value Kp, and the refrigerant pressure on the outlet side of the chiller 16 is set. The higher the value, the smaller the minimum rotation speed of the compressor 11.

In the liquid back suppression control according to the third embodiment, it is determined that the lower the refrigerant pressure on the outlet side of the chiller 16 detected by the chiller side pressure sensor 72e, the higher the minimum rotation speed of the compressor 11. As a result, the refrigerant discharge capacity of the compressor 11 becomes high as a whole.

The operation mode at this time is an operation mode in which the refrigerant circulates through the indoor evaporator 15 and the chiller 16, and the evaporation pressure adjusting valve 17 is arranged on the outlet side of the indoor evaporator 15. Therefore, when the refrigerant discharge capacity is increased by setting the minimum rotation speed of the compressor 11, the refrigerant flow rate on the indoor evaporator 15 side hardly changes, and the refrigerant flow rate on the chiller 16 side increases.

Here, the enthalpy of the intake refrigerant for the compressor 11 can be expressed by using the enthalpy of the outflow refrigerant from the indoor evaporator 15 and the enthalpy of the outflow refrigerant from the chiller 16. As described above, when the refrigerant discharge capacity of the compressor 11 is increased by the liquid back suppression control, the refrigerant flow rate on the indoor evaporator 15 side hardly changes, and the refrigerant flow rate on the chiller 16 side increases. Therefore, the enthalpy of the intake refrigerant with respect to the compressor 11 approaches the enthalpy of the outflow refrigerant from the chiller 16, and the enthalpy of the discharge refrigerant from the compressor 11 increases.

In the pressure-enthalpy diagram, it is known that the lower the pressure, the smaller the slope of the isentropic line with respect to the enthalpy. As a result, in the liquid back suppression control according to the third embodiment, the minimum rotation speed of the compressor 11 is adjusted according to the refrigerant pressure on the outlet side of the chiller 16, so that the discharge refrigerant of the compressor 11 is overheated. It is possible to suppress the liquid back to the compressor 11.

As described above, according to the refrigerating cycle apparatus 10 according to the third embodiment, even when the control mode is changed to the minimum rotation speed of the compressor 11, the configuration and operation common to those of the above-described embodiment can be achieved. The action and effect to be performed can be obtained in the same manner as in the above-described embodiment.

Regarding step S10 in the third embodiment, as a liquid back condition, it was determined whether or not the required refrigerant flow rate in the indoor evaporator 15 is equal to or less than the reference flow rate for suppressing the retention of refrigerating machine oil. It is not limited to this aspect. As the liquid back condition, it is also possible to adopt the same conditions as those in the above-described embodiment.

Although the present disclosure has been described above based on the embodiments, the present disclosure is not limited to the above-described embodiments. That is, various improvements and changes can be made without departing from the gist of the present disclosure.

In the above-described embodiment, the refrigerating cycle apparatus 10 is configured to include two, a first evaporator and a second evaporator, but the present invention is not limited to this embodiment. As a plurality of evaporators arranged in the refrigeration cycle apparatus 10, for example, a configuration in which three or more evaporators are connected in parallel can be adopted.

As a configuration in which the auxiliary evaporator 18 is arranged in addition to the indoor evaporator 15 and the chiller 16, as shown in FIG. 12, a configuration in which the auxiliary evaporator 18 is connected in parallel to the indoor evaporator 15 is adopted. Can be done. In this case, the refrigerant inlet side of the auxiliary evaporator 18 is connected so as to branch from the outlet of the first expansion valve 14a, and the refrigerant outlet side of the auxiliary evaporator 18 merges with the flow of the outflow refrigerant of the indoor evaporator 15. After that, it is desirable that the evaporation pressure adjusting valve 17 is connected so as to flow into the refrigerant inlet side.

Further, as shown in FIG. 13, it is also possible to adopt a configuration in which the auxiliary evaporator 18 is connected in parallel to the chiller 16. In this case, the refrigerant inlet side of the auxiliary evaporator 18 is connected so as to branch from the outlet of the second expansion valve 14b, and the refrigerant outlet side of the auxiliary evaporator 18 is connected from the chiller 16 upstream of the merging portion 13b. It is desirable to be connected so as to merge with the flow of the outflow refrigerant.

Further, in the above-described embodiment, the present disclosure is applied to the vehicle air conditioner 1 including the refrigerating cycle device 10, the high temperature side heat medium circuit 20, the low temperature side heat medium circuit 40, and the equipment heat medium circuit 50. However, the present invention is not limited to this aspect. The present disclosure can be applied to various configurations as long as it has at least the refrigeration cycle device 10 and the control device 70.

In the above-described embodiment, the cooling / cooling mode has been mentioned as a specific example of the operation mode to which the present disclosure is applied, but the present invention is not limited to this mode. Various modes shall be adopted as long as the operation mode ensures that the refrigerant is circulated to the indoor evaporator 15 and the chiller 16 and the flow rate of the refrigerant flowing to the indoor evaporator 15 is such that the retention of the refrigerating machine oil can be suppressed. It is also possible to apply it to the dehumidifying heating cooling mode.

In the above-described embodiment, an example in which the indoor evaporator 15 is adopted as an example of the first evaporator and the chiller 16 is adopted as an example of the second evaporator has been described, but the present invention is not limited to this embodiment. The present disclosure can be applied to various aspects as long as the first evaporator and the second evaporator are arranged in the refrigeration cycle device 10. For example, the cooling target cooled by the first evaporator and the second evaporator can be different from the blown air or the heat medium in the above-described embodiment.

It is also possible to adopt a configuration in which the arrangement positions of the first evaporator and the second evaporator are significantly different. For example, there may be a case where the first evaporator is arranged for air conditioning on the front side of the vehicle and the second evaporator is arranged for air conditioning on the rear side of the vehicle.

Further, in the above-described embodiment, an example in which the heat medium refrigerant heat exchanger 12 is adopted as the condenser is given, but the present invention is not limited to this embodiment. As the condenser, it suffices if the heat of the high-pressure refrigerant can be dissipated to condense the refrigerant. For example, an indoor condenser that dissipates the heat of the high-pressure refrigerant to the blown air to condense the refrigerant can also be adopted. ..

Although the present disclosure has been described in accordance with the examples, it is understood that the present disclosure is not limited to the examples and structures. The present disclosure also includes various variations and variations within a uniform range. In addition, various combinations and forms, as well as other combinations and forms that include only one element, more, or less, are within the scope and scope of the present disclosure.

Claims (10)

1. A compressor (11) that compresses and discharges a refrigerant containing refrigerating machine oil, and
   A condenser (12) that condenses the refrigerant discharged from the compressor, and
   A branch portion (13a) for branching the refrigerant flowing out of the condenser, and
   A first decompression unit (14a) that decompresses the refrigerant flowing out from one of the outlets in the branch unit, and
   A first evaporator (15) for evaporating the refrigerant flowing out of the first decompression unit, and
   A second decompression unit (14b) that decompresses the refrigerant that has flowed out from the other end of the outlet at the branch unit, and
   A second evaporator (16) for evaporating the refrigerant flowing out of the second decompression unit, and
   A confluence portion (13b) that merges the refrigerant that has flowed out of the first evaporator and the refrigerant that has flowed out of the second evaporator and guides the refrigerant to the compressor.
   It has a first decompression unit and a control unit (70) that controls the operation of the second decompression unit.
   The control unit
   In an operation mode in which the refrigerant is circulated to the first evaporator and the second evaporator, and the flow rate of the refrigerant flowing through the first evaporator is equal to or higher than the reference flow rate for suppressing the retention of the refrigerating machine oil. A determination unit (70b) for determining whether or not the liquid back condition regarding the liquid back in which the liquid phase refrigerant flows into the compressor is satisfied.
   When the determination unit determines that the liquid back condition is satisfied, the refrigerant pressure at the outlet of the second evaporator is lowered until the refrigerant discharged from the compressor has a degree of superheat. A refrigeration cycle device including a decompression control unit (70c) that controls the operation of the second decompression unit.
2. Evaporation pressure adjusting valve (17) arranged between the outlet of the first evaporator and the confluence portion, which reduces the pressure of the refrigerant flowing out of the first evaporator and adjusts the refrigerant evaporation pressure in the first evaporator. The refrigeration cycle apparatus according to claim 1, wherein the refrigerating cycle apparatus has.
3. The refrigerating cycle apparatus according to claim 1 or 2, wherein the determination unit (70b) determines that the liquid back condition is satisfied when the cooling load in the first evaporator (15) is smaller than the reference (KL). ..
4. It has a refrigerant pressure detection unit (72e) that detects the refrigerant pressure on the outlet side of the second evaporator (16).
   The decompression control unit (70c) has the target pressure determined from the cooling load in the first evaporator (15) and the target pressure when the determination unit (70b) determines that the liquid back condition is satisfied. One of claims 1 to 3 for controlling the opening degree of the second decompression unit (14b) so that the refrigerant pressure approaches the target pressure according to the difference from the refrigerant pressure detected by the refrigerant pressure detection unit. The refrigeration cycle device according to one.
5. It has a high-pressure side temperature detection unit (72d) that detects the temperature of the refrigerant discharged from the compressor.
   A claim that the determination unit (70b) determines that the liquid back condition is satisfied when the refrigerant discharged from the compressor does not have a degree of superheat based on the detection result of the high pressure side temperature detection unit. The refrigeration cycle apparatus according to 1 or 2.
6. The decompression control unit (70c) has a target superheat degree determined from the cooling load in the first evaporator (15) when the determination unit (70b) determines that the liquid back condition is satisfied. The claim that controls the opening degree of the second decompression unit (14b) so that the superheat degree of the refrigerant approaches the target superheat degree according to the difference from the superheat degree of the refrigerant detected by the high pressure side temperature detection unit. 5. The refrigeration cycle apparatus according to 5.
7. A compressor (11) that compresses and discharges a refrigerant containing refrigerating machine oil, and
   A condenser (12) that condenses the refrigerant discharged from the compressor, and
   A branch portion (13a) for branching the refrigerant flowing out of the condenser, and
   A first decompression unit (14a) that decompresses the refrigerant flowing out from one of the outlets in the branch unit, and
   A first evaporator (15) for evaporating the refrigerant flowing out of the first decompression unit, and
   A second decompression unit (14b) that decompresses the refrigerant that has flowed out from the other end of the outlet at the branch unit, and
   A second evaporator (16) for evaporating the refrigerant flowing out of the second decompression unit, and
   A confluence portion (13b) that merges the refrigerant that has flowed out of the first evaporator and the refrigerant that has flowed out of the second evaporator and guides the refrigerant to the compressor.
   It has a control unit (70) that controls the operation of the compressor, and has.
   The control unit
   In an operation mode in which the refrigerant is circulated to the first evaporator and the second evaporator, and the flow rate of the refrigerant flowing through the first evaporator is equal to or higher than the reference flow rate for suppressing the retention of the refrigerating machine oil. A determination unit (70b) for determining whether or not the liquid back condition regarding the liquid back in which the liquid phase refrigerant flows into the compressor is satisfied.
   When the determination unit determines that the liquid back condition is satisfied, the refrigerant pressure at the outlet of the second evaporator is lowered until the refrigerant discharged from the compressor has a degree of superheat. A refrigeration cycle device including a discharge capacity control unit (70d) that controls the operation of the compressor.
8. Evaporation pressure adjusting valve (17) arranged between the outlet of the first evaporator and the confluence portion, which reduces the pressure of the refrigerant flowing out of the first evaporator and adjusts the refrigerant evaporation pressure in the first evaporator. The refrigeration cycle apparatus according to claim 7, wherein the refrigerating cycle apparatus has.
9. The refrigerating cycle apparatus according to claim 7 or 8, wherein the determination unit (70b) determines that the liquid back condition is satisfied when the cooling load in the first evaporator (15) is smaller than the reference (KL). ..
10. When the determination unit (70b) determines that the liquid back condition is satisfied, the discharge capacity control unit (70d) determines the refrigerant pressure on the outlet side of the first evaporator (15) and the second. The refrigerant discharge capacity of the compressor is controlled so that the refrigerant discharged from the compressor has a degree of overheating according to the lower of the refrigerant pressures on the outlet side of the evaporator (16). The refrigerating cycle apparatus according to any one of claims 7 to 9.

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