Refrigeration cycle system

Abstract

To inhibit a liquid refrigerant from remaining in a second condenser when a first circulation circuit where a refrigerant is condensed in a second condenser is changed to a second circulation circuit where the refrigerant is not condensed in the second condenser.SOLUTION: A refrigeration circuit system includes a compressor 11 that compresses and discharges a refrigerant, a first condenser 12 and second condenser 15 each of which exchanges heat energy with the refrigerant and thus condenses the refrigerant, an evaporator 20 that exchanges heat energy with the refrigerant and thus evaporates the refrigerant, a first expansion valve 14 that depressurizes and expands the refrigerant which flows into the second condenser, a second expansion valve 19 that depressurizes and expands the refrigerant which flows into the evaporator, refrigerant route changers 17 and 23 that change a first circulation route along which the refrigerant circulates orderly from the compressor through the first condenser, first expansion valve, second condenser, second expansion valve, and evaporator to the compressor, and a second circulation route along which the refrigerant circulates orderly from the compressor through the first condenser, second expansion valve, and evaporator to the, compressor, and a control unit 40 that implements dryness boost control of boosting the dryness of the refrigerant in the second condenser when the first circulation route is changed to the second circulation route.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The present invention relates to a refrigeration cycle device that has two condensers and is capable of switching between a refrigerant circulation circuit that uses one of the condensers and a refrigerant circulation circuit that does not use the other condenser. [Background technology]

[0002] Conventionally, Patent Document 1 describes a refrigeration cycle device having two condensers, an indoor condenser and an outdoor heat exchanger. In this conventional technology, it is possible to switch between a refrigerant circulation circuit in which the refrigerant discharged from the compressor flows through the outdoor heat exchanger and is condensed therein, and a refrigerant circulation circuit in which the refrigerant discharged from the compressor bypasses the outdoor heat exchanger and is not condensed therein. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 6149580 Summary of the Invention [Problem to be solved by the invention]

[0004] In the above-mentioned conventional technology, when switching from a refrigerant circulation circuit (in other words, the first circulation circuit) that condenses the refrigerant in the outdoor heat exchanger (in other words, the second condenser) to a refrigerant circulation circuit (in other words, the second circulation circuit) that does not condense the refrigerant in the outdoor heat exchanger, liquid refrigerant may be left behind in the outdoor heat exchanger, and there is a risk of a shortage of refrigerant circulating in the cycle in the refrigerant circulation circuit after switching.

[0005] In view of the above, an object of the present invention is to suppress liquid refrigerant from remaining in the second condenser when switching from a first circulation circuit, in which the refrigerant is condensed in the second condenser, to a second circulation circuit, in which the refrigerant is not condensed in the second condenser. [Means for solving the problem]

[0006] In order to achieve the above object, the refrigeration cycle device according to claim 1 comprises: a compressor (11) that compresses and discharges a refrigerant; a first condenser (12) and a second condenser (15) for condensing a refrigerant by heat exchange; an evaporator (20) that evaporates a refrigerant by heat exchange; a first expansion valve (14) for reducing the pressure and expanding the refrigerant flowing into the second condenser; a second expansion valve (19) for reducing the pressure and expanding the refrigerant flowing into the evaporator; a refrigerant path switching unit (17, 23) that switches between a first circulation path in which the refrigerant circulates through the compressor, the first condenser, the first expansion valve, the second condenser, the second expansion valve, the evaporator, and the compressor in this order, and a second circulation path in which the refrigerant circulates through the compressor, the first condenser, the second expansion valve, the evaporator, and the compressor in this order; The refrigerant condenser further includes a control unit (40) that performs a dryness increase control for increasing the dryness of the refrigerant in the second condenser when switching from the first circulation path to the second circulation path.

[0007] According to this, when switching from the first circulation path to the second circulation path, the dryness of the refrigerant in the second condenser increases, and the liquid refrigerant in the second condenser decreases. Therefore, when switching from the first circulation path to the second circulation path, it is possible to suppress the liquid refrigerant from remaining in the second condenser.

[0008] In order to achieve the above object, the refrigeration cycle device according to claim 2 comprises: a compressor (11) that compresses and discharges a refrigerant; a first condenser (12) that exchanges heat between the air to be blown into the space to be air-conditioned and a refrigerant, thereby dissipating heat from the refrigerant; a second condenser (15) for exchanging heat between the refrigerant and outside air; an evaporator (20) that evaporates a refrigerant by exchanging heat between the refrigerant and air before passing through the first condenser; a first expansion valve (14) for reducing the pressure and expanding the refrigerant flowing into the second condenser; a second expansion valve (19) for reducing the pressure and expanding the refrigerant flowing into the evaporator; a low-pressure refrigerant passage (16) that guides the refrigerant flowing out of the second condenser to a suction side of the compressor, bypassing the second expansion valve and the evaporator; a refrigerant path switching unit (17, 23) that switches between a first circulation path in which the refrigerant circulates through the compressor, the first condenser, the first expansion valve, the second condenser, the second expansion valve, the evaporator, and the compressor in this order, and a second circulation path in which the refrigerant circulates through the compressor, the first condenser, the second expansion valve, the evaporator, and the compressor in this order, and opens and closes the low-pressure refrigerant path; The refrigerant circulation system further includes a control unit (40) that controls the refrigerant path switching unit so that the low-pressure refrigerant path is opened when switching from the first circulation path to the second circulation path.

[0009] According to this, by opening the first on-off valve, the outlet side of the second condenser is connected to the low-pressure refrigerant circuit, so that the refrigerant inside the second condenser is actively discharged and the liquid refrigerant inside the second condenser is further reduced. Therefore, it is possible to suppress the liquid refrigerant from remaining in the second condenser when switching from the first circulation path to the second circulation path.

[0010] In addition, the reference symbols in parentheses for each means described in this column and in the claims indicate the correspondence with the specific means described in the embodiments described later. [Brief description of the drawings]

[0011] [Figure 1] 1 is an overall configuration diagram showing a refrigeration cycle device of a first embodiment. [Diagram 2] 3 is a time chart showing an example of a control process executed by a control device of the refrigeration cycle device of the first embodiment. [Diagram 3] 3 is a Mollier diagram showing changes in the state of a refrigerant in the refrigeration cycle device of the first embodiment. FIG. [Figure 4] 5 is a graph illustrating an upper limit storage amount in the dryness fraction increase control of the first embodiment. [Diagram 5] 4 is a graph illustrating a lower limit dryness fraction in the dryness fraction increase control of the first embodiment. [Figure 6] 6 is a time chart showing an example of a control process executed by a control device of a refrigeration cycle device of a second embodiment. [Figure 7] 10 is a time chart showing an example of a control process executed by a control device of a refrigeration cycle device of a third embodiment. [Figure 8] FIG. 11 is an overall configuration diagram showing a refrigeration cycle device of a fourth embodiment. [Figure 9] FIG. 11 is an overall configuration diagram showing a refrigeration cycle device of a fifth embodiment. [Figure 10] FIG. 13 is an overall configuration diagram showing a refrigeration cycle device of a sixth embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] (First embodiment) A refrigeration cycle device 10 according to the present embodiment will be described with reference to the drawings. The refrigeration cycle device 10 shown in Fig. 1 is applied to a vehicle air conditioner for a hybrid vehicle. The vehicle air conditioner to which the refrigeration cycle device 10 is applied cools or heats air to be blown into a vehicle interior, which is a space to be air-conditioned.

[0013] The refrigeration cycle device 10 can be switched between a cooling mode refrigerant flow path, a dehumidifying and heating mode refrigerant flow path, and a heating mode refrigerant flow path. The cooling mode is an operation mode during cooling operation to cool the vehicle interior. The dehumidifying and heating mode is an operation mode during dehumidifying operation to heat the vehicle interior while dehumidifying it. The heating mode is an operation mode during heating operation to heat the vehicle interior.

[0014] The refrigeration cycle apparatus 10 can execute a first dehumidification heating mode, a second dehumidification heating mode, and a third dehumidification heating mode as the dehumidification heating mode.

[0015] In this embodiment, the refrigerant in the refrigeration cycle apparatus 10 is a fluorocarbon-based refrigerant, and the refrigeration cycle apparatus 10 is configured as a subcritical refrigeration cycle in which the pressure of the high-pressure refrigerant does not exceed the critical pressure of the refrigerant.

[0016] The refrigeration cycle device 10 includes a compressor 11, an indoor condenser 12, a first refrigerant passage 13, a first expansion valve 14, an outdoor heat exchanger 15, a second refrigerant passage 16, a first on-off valve 17, a third refrigerant passage 18, a second expansion valve 19, an indoor evaporator 20, an accumulator 21, a fourth refrigerant passage 22, a second on-off valve 23, a check valve 24, a constant pressure valve 25, and a control device 40.

[0017] The compressor 11 is disposed in an engine room of the vehicle, and draws in, compresses, and discharges refrigerant in the refrigeration cycle device 10. The compressor 11 is an electric compressor that includes an electric motor and a compression mechanism that is driven by the electric motor to compress the refrigerant, and changes the compression power according to the rotation speed of the electric motor. The compression mechanism of the compressor 11 is, for example, one of various compression mechanisms such as a scroll type compression mechanism or a vane type compression mechanism.

[0018] The inlet side of the interior condenser 12 is connected to the discharge port side of the compressor 11. The interior condenser 12 is disposed inside a casing 31 of the interior air conditioning unit 30. The interior condenser 12 is a first condenser that condenses the high-pressure refrigerant discharged from the compressor 11 by heat exchange with air blown into the vehicle cabin, and dissipates heat from the high-pressure refrigerant.

[0019] A first refrigerant passage 13 that guides the refrigerant flowing out from the indoor condenser 12 to the outdoor heat exchanger 15 is connected to the outlet side of the indoor condenser 12. A first expansion valve 14 that is configured to be able to change the passage area of ​​the first refrigerant passage 13 is arranged in the first refrigerant passage 13.

[0020] The first expansion valve 14 is an electric variable throttle mechanism having a valve body configured to be able to change the throttle opening and an electric actuator consisting of a stepping motor that changes the throttle opening of the valve body. The first expansion valve 14 increases or decreases the throttle opening of the first expansion valve 14 according to a control signal output from the control device 40.

[0021] The larger the throttle opening of the first expansion valve 14, the larger the passage area of ​​the first refrigerant passage 13. The first expansion valve 14 reduces the pressure of the refrigerant passing through it according to its throttle opening, thereby causing the refrigerant to expand.

[0022] For example, when the first expansion valve 14 is fully open, it allows the refrigerant to pass without decompressing and expanding it. When the first expansion valve 14 is fully closed, it blocks the flow of the refrigerant and prevents the refrigerant from flowing into the exterior heat exchanger 15.

[0023] The outlet side of the first expansion valve 14 is connected to the inlet side of the outdoor heat exchanger 15. The outdoor heat exchanger 15 is a refrigerant-outdoor air heat exchanger that exchanges heat between the refrigerant and the outdoor air. The outdoor heat exchanger 15 serves as an evaporator that evaporates the refrigerant to exert a heat absorption effect in the heating mode, etc., and serves as a second condenser that condenses the refrigerant to exert a heat dissipation effect in the cooling mode, etc.

[0024] A second refrigerant passage 16 and a third refrigerant passage 18 are connected to the outlet side of the outdoor heat exchanger 15. The second refrigerant passage 16 is a low-pressure refrigerant passage that guides the refrigerant flowing out from the outdoor heat exchanger 15 to the inlet side of the accumulator 21. The third refrigerant passage 18 is a refrigerant passage that guides the refrigerant flowing out from the outdoor heat exchanger 15 to the inlet side of the indoor evaporator 20.

[0025] A first on-off valve 17 is disposed in the second refrigerant passage 16. The first on-off valve 17 is a solenoid valve that opens and closes the second refrigerant passage 16. The first on-off valve 17 is a refrigerant path switching unit that switches the refrigerant path. The operation of the first on-off valve 17 is controlled by a control signal output from the control device 40.

[0026] A second expansion valve 19 configured to be able to change the passage area of ​​the third refrigerant passage 18 is disposed in the third refrigerant passage 18. The second expansion valve 19 is an electric variable throttling mechanism similar to the first expansion valve 14, and increases or decreases the throttling opening of the second expansion valve 19 according to a control signal output from the control device 40. Specifically, the second expansion valve 19 reduces the pressure of the refrigerant passing through it according to its throttling opening, thereby decompressing and expanding the refrigerant. When fully open, the second expansion valve 19 allows the refrigerant to pass through without reducing the pressure and expanding it. When fully closed, the second expansion valve 19 blocks the flow of the refrigerant.

[0027] The outlet side of the second expansion valve 19 is connected to the inlet side of the indoor evaporator 20. The indoor evaporator 20 is disposed in a casing 31 of the indoor air-conditioning unit 30, upstream of the air flow of the indoor condenser 12. A refrigerant flows through the indoor evaporator 20, for example, in a cooling mode and a dehumidifying heating mode. The indoor evaporator 20 is an evaporator that evaporates the refrigerant flowing therethrough by heat exchange with the air before passing through the indoor condenser 12, and cools the air by exerting a heat absorbing effect.

[0028] The outlet side of the indoor evaporator 20 is connected to the inlet side of the accumulator 21 via a constant pressure valve 25. The constant pressure valve 25 is a mechanical pressure reducing device that reduces the pressure of the refrigerant passing through it by mechanical operation. Specifically, the constant pressure valve 25 reduces the pressure of the refrigerant passing through it while maintaining the pressure of the refrigerant at the outlet side of the indoor evaporator 20 at a predetermined value.

[0029] The accumulator 21 is a gas-liquid separator that separates the refrigerant that flows into it into gas and liquid and stores the excess refrigerant in the cycle. The gas-phase refrigerant outlet of the accumulator 21 is connected to the suction port side of the compressor 11. The accumulator 21 prevents the liquid-phase refrigerant from being sucked into the compressor 11, and prevents liquid compression in the compressor 11.

[0030] The refrigeration cycle apparatus 10 is provided with a bypass passage 22 that guides the refrigerant upstream of the first expansion valve 14 in the first refrigerant passage 13 to the inlet side of the second expansion valve 19. The bypass passage 22 is a refrigerant passage that guides the refrigerant flowing out of the indoor condenser 12 to the inlet side of the second expansion valve 19 while bypassing the first expansion valve 14 and the outdoor heat exchanger 15.

[0031] A second on-off valve 23 is disposed in the bypass passage 22. The second on-off valve 23 is a solenoid valve that opens and closes the bypass passage 22. The second on-off valve 23 is a refrigerant path switching unit that switches the refrigerant path. The operation of the second on-off valve 23 is controlled by a control signal output from the control device 40.

[0032] A check valve 24 is disposed in the third refrigerant passage 18 upstream of the junction with the bypass passage 22. The check valve 24 allows the refrigerant to flow from the outlet side of the outdoor heat exchanger 15 to the inlet side of the second expansion valve 19, while prohibiting the refrigerant from flowing from the inlet side of the second expansion valve 19 to the outlet side of the outdoor heat exchanger 15. The check valve 24 prevents the refrigerant that has merged with the third refrigerant passage 18 from the bypass passage 22 from flowing toward the outdoor heat exchanger 15.

[0033] The interior air conditioning unit 30 is disposed inside the instrument panel at the front end of the vehicle interior. The interior air conditioning unit 30 includes a casing 31 that forms the outer shell of the unit, and contains a blower 32, a heater core 34, an interior condenser 12, an interior evaporator 20, etc.

[0034] The casing 31 forms a passage for air to be blown into the vehicle cabin, and is made of a resin (e.g., polypropylene) that has a certain degree of elasticity and excellent strength. An inside / outside air switching device 33 is disposed on the most upstream side of the air flow in the casing 31, which switches between introducing outside air, which is air outside the vehicle cabin, and inside air, which is air inside the vehicle cabin.

[0035] The inside / outside air switching device 33 is formed with an inside air inlet for introducing inside air into the casing 31 and an outside air inlet for introducing outside air. An inside / outside air switching door is disposed inside the inside / outside air switching device 33, which adjusts the opening areas of the inside air inlet and the outside air inlet to change the ratio of the air volumes of the inside air and the outside air.

[0036] A blower 32 is disposed downstream of the inside / outside air switching device 33 in the air flow direction, and blows the air introduced through the inside / outside air switching device 33 toward the inside of the vehicle cabin. The blower 32 is, for example, an electric sirocco fan. The amount of air blown by the blower 32 is controlled by a control signal output from the control device 40.

[0037] The indoor evaporator 20, the heater core 34, and the indoor condenser 12 are arranged in this order in the air flow direction on the air flow downstream side of the blower 32. In other words, the indoor evaporator 20 is arranged on the air flow upstream side with respect to the indoor condenser 12 and the heater core 34.

[0038] The heater core 34 is a heating heat exchanger that exchanges heat between the coolant of the engine that outputs the driving force for running the vehicle and the air blown into the vehicle cabin. The heater core 34 is disposed upstream of the air flow relative to the interior condenser 12. A cool air bypass passage 35 is formed in the casing 31, which allows the air that has passed through the interior evaporator 20 to bypass the interior condenser 12 and the heater core 34.

[0039] An air mix door 36 is disposed downstream of the indoor evaporator 20 in the air flow and upstream of the indoor condenser 12 and the heater core 34 in the air flow, and adjusts the ratio of the air volume passing through the indoor condenser 12 and the heater core 34 and the air passing through the cold air bypass passage 35 after passing through the indoor evaporator 20.

[0040] A mixing space is provided on the air flow downstream side of the indoor condenser 12 and the air flow downstream side of the cold air bypass passage 35, for mixing the air that has passed through the indoor condenser 12 and the air that has passed through the cold air bypass passage 35.

[0041] An air outlet for blowing air into the vehicle cabin is provided at the most downstream side of the blown air flow of the casing 31, and the conditioned air mixed in the mixing space is blown out from the air outlet into the vehicle cabin. The air mix door 36 is driven by a servo motor (not shown) that operates according to a control signal output from the control device 40.

[0042] As shown in FIG. 1, the refrigeration cycle apparatus 10 includes a first temperature sensor 42, a first pressure sensor 44, a second temperature sensor 46, a third temperature sensor 48, a fourth temperature sensor 50 and an outside air temperature sensor 52.

[0043] The first temperature sensor 42 and the first pressure sensor 44 are provided in the first refrigerant passage 13 between the indoor condenser 12 and the first expansion valve 14. The first temperature sensor 42 detects the temperature of the refrigerant flowing out from the indoor condenser 12. The first pressure sensor 44 detects the pressure of the refrigerant flowing out from the indoor condenser 12.

[0044] The second temperature sensor 46 is provided at a refrigerant outlet of the exterior heat exchanger 15 , and detects the temperature of the refrigerant flowing out from the exterior heat exchanger 15 .

[0045] The third temperature sensor 48 is provided in the casing 31 of the indoor air conditioning unit 30 downstream of the air flow of the indoor evaporator 20, and detects the temperature Te of the air blown out from the indoor evaporator 20 (hereinafter referred to as the evaporator blowout temperature Te).

[0046] The fourth temperature sensor 50 is provided in a refrigerant flow path from the interior evaporator 20 to the constant pressure valve 25, and detects the temperature of the refrigerant flowing out from the interior evaporator 20. The outside air temperature sensor 52 is provided outside the vehicle compartment, and detects the outside air temperature Tam.

[0047] The control device 40 is an electronic control device configured with a microcomputer including a CPU, a ROM, a RAM, etc. and its peripheral circuits. The control device 40 is a control unit that executes various control processes according to computer programs previously stored in the ROM, etc.

[0048] The control device 40 receives detection signals representing detection values ​​from each of the sensors 42, 44, 46, 48, 50, and 52. The control device 40 receives detection signals representing detection values ​​from a group of various sensors for air conditioning control, such as an inside air sensor, a solar radiation sensor, a discharge temperature sensor, and a blown temperature sensor. The inside air sensor detects the temperature Tr inside the vehicle cabin. The solar radiation sensor detects the amount of solar radiation Ts inside the vehicle cabin. The discharge temperature sensor detects the temperature Td of the refrigerant discharged from the compressor 11. The blown temperature sensor detects the blown temperature TAV of the air blown from the interior air conditioning unit 30 into the vehicle cabin.

[0049] An operation panel (not shown) arranged on the instrument panel is connected to the control device 40, and operation signals are input from various operation switches provided on the operation panel. The various operation switches provided on the operation panel include an air conditioner switch for setting whether or not the interior air conditioning unit 30 cools the air, a temperature setting switch for setting the preset temperature inside the vehicle cabin, and the like.

[0050] The air conditioner switch is turned on by a passenger when the vehicle air conditioner is to be operated in cooling or dehumidifying mode. That is, when the air conditioner switch is on, the air is cooled by the interior evaporator 20 in the cooling mode or the dehumidifying and heating mode.

[0051] When the air conditioner switch is off, in the heating mode, the air is heated by the interior condenser 12 without being cooled by the interior evaporator 20.

[0052] When the air conditioner switch is on, the controller 40 determines the operation mode of the vehicle air conditioner to be one of the cooling mode, the first dehumidification and heating mode, the second dehumidification and heating mode, or the third dehumidification and heating mode based on the target outlet temperature TAO.

[0053] The target outlet temperature TAO is calculated from a predetermined formula based on the interior temperature Tset set by the temperature setting switch in the operation panel, the interior temperature Tr detected by the interior air sensor, the outside air temperature Tam detected by the outside air temperature sensor 52, and the amount of solar radiation Ts detected by the solar radiation sensor.

[0054] When the air conditioner switch is on, if the target air outlet temperature TAO is lower than the cooling reference temperature α, the control device 40 determines the operation mode of the vehicle air conditioner to be the cooling mode. The cooling reference temperature α is the maximum value of the target air outlet temperature TAO to be realized in the cooling mode.

[0055] When the air conditioner switch is on, if the target outlet temperature TAO is equal to or higher than the cooling reference temperature α and lower than the first determination value T1, the controller 40 determines the operation mode of the vehicle air conditioner to be the first dehumidification heating mode.

[0056] The first determination value T1 is the maximum value of the target air outlet temperature TAO to be realized in the first dehumidification heating mode. The first determination value T1 is a value greater than the cooling reference temperature α.

[0057] When the air conditioner switch is on and the target blowing temperature TAO is equal to or higher than the first judgment value T1, the control device 40 determines that the heating capacity of the interior condenser 12 is insufficient if dehumidification operation is performed in the first dehumidification heating mode, and determines the operating mode of the vehicle air conditioner to be either the second dehumidification heating mode or the third dehumidification heating mode.

[0058] Specifically, when the target blowing temperature TAO is greater than the second judgment value T2, the second dehumidification heating mode is selected. The second judgment value T2 is the minimum value of the target blowing temperature TAO to be realized in the second dehumidification heating mode. The second judgment value T2 is a value equal to or greater than the first judgment value T1, which is equal to or greater than the cooling reference temperature α.

[0059] If the target blowing temperature TAO is equal to or lower than the second judgment value T2, the third dehumidification heating mode is selected. That is, when attempting to make the blowing temperature TAV into the vehicle compartment equal to the target blowing temperature TAO while maintaining the dehumidification capacity of the interior evaporator 20 at a required predetermined level, it is determined that the heating capacity of the interior condenser 12 would be excessive if dehumidification operation was performed in the second dehumidification heating mode, and the third dehumidification heating mode is selected.

[0060] In the cooling mode, the control device 40 shuts off the second refrigerant passage 16 with the first on-off valve 17, shuts off the bypass passage 22 with the second on-off valve 23, and fully opens the first expansion valve 14. As a result, the control device 40 establishes a cooling circulation path in which the refrigerant discharged from the compressor 11 flows through the indoor condenser 12, the first expansion valve 14, the outdoor heat exchanger 15, the check valve 24, the second expansion valve 19, the indoor evaporator 20, the constant pressure valve 25, and the accumulator 21 in this order, and then returns to the compressor 11, as shown by the outlined arrow in FIG.

[0061] In the cooling mode, the control device 40 closes the air passages of the heater core 34 and the interior condenser 12 by the air mix door 36, so that the entire flow rate of the blown air after passing through the interior evaporator 20 flows into the cool air bypass passage 35. Then, the refrigerant that has flowed into the interior condenser 12 flows out of the interior condenser 12 with almost no heat exchange with the air.

[0062] In the cooling mode, the control device 40 refers to a control map stored in advance in the control device 40 based on the target air outlet temperature TAO, and determines a target evaporator outlet temperature TEO, which is a target value for the temperature of air blown out from the interior evaporator 20. Then, based on the deviation between the target evaporator outlet temperature TEO and the evaporator outlet temperature Te detected by the third temperature sensor 48, the rotation speed of the compressor 11 is controlled so that the air outlet temperature TAV into the vehicle interior approaches the target air outlet temperature TAO.

[0063] The control device 40 controls the throttle opening of the second expansion valve 19 so that the degree of subcooling of the refrigerant flowing into the second expansion valve 19 approaches a predetermined target degree of subcooling so as to maximize the coefficient of performance (hereinafter referred to as COP) of the cycle. The degree of subcooling of the refrigerant flowing into the second expansion valve 19 is calculated, for example, from the refrigerant temperature at the outlet of the outdoor heat exchanger 15 detected by the second temperature sensor 46 and the refrigerant pressure at the outlet of the outdoor heat exchanger 15 detected by the first pressure sensor 44. At this time, since the first expansion valve 14 is in a fully open state, the pressure of the refrigerant at the outlet of the outdoor heat exchanger 15 can be detected by the first pressure sensor 44 provided at the outlet of the indoor condenser 12.

[0064] As described above, in the cooling mode, the air mix door 36 closes the air passages of the interior condenser 12 and the heater core 34, so that the air cooled by the interior evaporator 20 can be blown out into the vehicle interior. This allows the vehicle interior to be cooled.

[0065] In the first dehumidifying and heating mode, the control device 40 shuts off the second refrigerant passage 16 with the first on-off valve 17, shuts off the bypass passage 22 with the second on-off valve 23, and sets the first expansion valve 14 and the second expansion valve 19 to a throttled state or a fully open state, respectively. As a result, the control device 40 establishes a first circulation path in which the refrigerant discharged from the compressor 11 flows through the indoor condenser 12, the first expansion valve 14, the outdoor heat exchanger 15, the check valve 24, the second expansion valve 19, the indoor evaporator 20, the constant pressure valve 25, and the accumulator 21 in this order and returns to the compressor 11, as shown by the outlined horizontal arrow in FIG. In this first circulation path, the outdoor heat exchanger 15 and the indoor evaporator 20 are connected in series in the refrigerant flow. The first circulation path is the same as the above-mentioned cooling circulation path.

[0066] In the first dehumidification heating mode, the control device 40 controls the rotation speed of the compressor 11 in the same manner as in the cooling mode. In addition, the control device 40 closes the cool air bypass passage 35 by the air mix door 36, so that the total flow rate of the blown air after passing through the indoor evaporator 20 passes through the heater core 34 and the air passage of the indoor condenser 12.

[0067] In the first dehumidification heating mode, the controller 40 changes the throttle opening of the first expansion valve 14 and the throttle opening of the second expansion valve 19 in accordance with the target blowing temperature TAO. Specifically, as the target blowing temperature TAO increases, the controller 40 reduces the passage area of ​​the first refrigerant passage 13 by the first expansion valve 14 and increases the passage area of ​​the third refrigerant passage 18 by the second expansion valve 19. As a result, in the first dehumidification heating mode, the exterior heat exchanger 15 may function as an evaporator or as a condenser.

[0068] In the first dehumidifying and heating mode, the outdoor heat exchanger 15 is disposed upstream of the indoor evaporator 20 in the refrigerant flow, and since the refrigerant pressure of the indoor evaporator 20 cannot be lowered below the 0°C saturation pressure in order to prevent frosting of the indoor evaporator 20, the refrigerant pressure of the outdoor heat exchanger 15 cannot be lowered below the 0°C saturation pressure either. Therefore, when the outdoor air temperature Tam is extremely low, for example below freezing point, even if the second expansion valve 19 is fully or nearly fully open to lower the refrigerant temperature of the outdoor heat exchanger 15 to the maximum extent, the outdoor air temperature Tam will be lower than the refrigerant temperature of the outdoor heat exchanger 15, and the outdoor heat exchanger 15 will function as a condenser.

[0069] As described above, in the first dehumidification and heating mode, the air cooled and dehumidified by the interior evaporator 20 can be heated by the interior condenser 12 and blown into the vehicle cabin. This allows dehumidification and heating of the vehicle cabin to be achieved.

[0070] In the second dehumidifying and heating mode, the controller 40 opens the first on-off valve 17 to open the second refrigerant passage 16, and also opens the second on-off valve 23 to open the bypass passage 22, and throttles the first expansion valve 14 and the second expansion valve 19. In this way, the controller 40 establishes the second circulation path indicated by the outlined diagonal line arrow in FIG.

[0071] The second circulation path is a path in which the refrigerant discharged from the compressor 11 flows to the indoor condenser 12, and then flows from the indoor condenser 12 to the first expansion valve 14, the outdoor heat exchanger 15, the first opening / closing valve 17, and the accumulator 21 in this order, and also flows from the indoor condenser 12 to the second opening / closing valve 23, the second expansion valve 19, the indoor evaporator 20, the constant pressure valve 25, and the accumulator 21 in this order, and further, the refrigerant that has joined at the accumulator 21 returns from the accumulator 21 to the compressor 11. That is, in the second circulation path, the outdoor heat exchanger 15 and the indoor evaporator 20 are connected in parallel in the refrigerant flow. Therefore, in the refrigeration cycle of the second dehumidification heating mode, the outdoor heat exchanger 15 always functions as an evaporator.

[0072] When the refrigerant circulates in the second circulation path, the check valve 24 prevents the refrigerant from flowing back from the bypass passage 22 to the outlet side of the outdoor heat exchanger 15. In addition, the constant pressure valve 25 maintains the refrigerant pressure in the indoor evaporator 20 higher than the refrigerant pressure in the outdoor heat exchanger 15.

[0073] In the second dehumidification heating mode, the control device 40 controls the rotation speed of the compressor 11 and closes the cool air bypass passage 35 with the air mix door 36 so that the air outlet temperature TAV into the passenger compartment approaches the target air outlet temperature TAO.

[0074] The control device 40 controls electric actuators that adjust the throttle opening of each of the first expansion valve 14 and the second expansion valve 19 so that the throttle opening of each of the first expansion valve 14 and the second expansion valve 19 each become predetermined predetermined openings for the second dehumidification heating mode.

[0075] As described above, in the second dehumidifying and heating mode, unlike the first dehumidifying and heating mode, the refrigerant flow path is such that the outdoor heat exchanger 15 and the indoor evaporator 20 are connected in parallel with respect to the refrigerant flow, so that the refrigerant flow rate to the indoor evaporator 20 can be reduced. Therefore, the amount of heat absorbed by the refrigerant in the indoor evaporator 20 can be reduced, and the temperature of the air dehumidified by the indoor evaporator 20 can be adjusted in a higher temperature range by the indoor condenser 12 than in the first dehumidifying and heating mode.

[0076] In the third dehumidification heating mode, the control device 40 closes the first on-off valve 17 to block the second refrigerant passage 16, opens the second on-off valve 23 to open the bypass passage 22, fully closes the first expansion valve 14 to prevent refrigerant from flowing into the outdoor heat exchanger 15, and throttles the second expansion valve 19.

[0077] 1 , the control device 40 establishes a third circulation path in which the refrigerant discharged from the compressor 11 flows through the indoor condenser 12, the second on-off valve 23, the second expansion valve 19, the indoor evaporator 20, the constant pressure valve 25, and the accumulator 21 in this order, before returning to the compressor 11. When the refrigerant circulates through the third circulation path, the check valve 24 prevents the refrigerant from flowing back from the bypass passage 22 to the outlet side of the outdoor heat exchanger 15.

[0078] In the refrigeration cycle of the third dehumidifying heating mode, the refrigerant pressure in the indoor evaporator 20 is maintained at a constant pressure by the action of the constant pressure valve 25. Specifically, the refrigerant pressure in the indoor evaporator 20 is maintained at a predetermined pressure higher than the 0° C. saturation pressure so that frosting of the indoor evaporator 20 can be prevented.

[0079] In the third dehumidification heating mode, similarly to the first dehumidification heating mode, the control device 40 controls the rotation speed of the compressor 11 and closes the cool air bypass passage 35 with the air mix door 36. For example, the control device 40 can increase the rotation speed of the compressor 11 to increase the compression power of the compressor 11, thereby increasing the heat dissipation capacity of the indoor condenser 12 to dissipate heat from the refrigerant, in other words, the heating capacity of the indoor condenser 12. In other words, it is possible to control the heating capacity while preventing frosting of the indoor evaporator 20.

[0080] Specifically, the control device 40 can increase the heating capacity of the indoor condenser 12 by increasing the compression power of the compressor 11 while maintaining the refrigerant pressure in the indoor evaporator 20 constant.

[0081] In the third dehumidification heating mode, the control device 40 controls the electric actuator that adjusts the throttle opening of the second expansion valve 19 so that the throttle opening becomes a predetermined predetermined opening for the third dehumidification heating mode.

[0082] As described above, in the third dehumidification and heating mode in which no refrigerant flows to the outdoor heat exchanger 15, the amount of heat exchanged by the outdoor heat exchanger 15 becomes zero. Therefore, in the third dehumidification and heating mode, it is possible to obtain a heating capacity intermediate between the first dehumidification and heating mode and the second dehumidification and heating mode.

[0083] Therefore, even under low outside air temperature conditions such as when the outside air temperature Tam is below 0°C, the operating mode of the vehicle air conditioning system can be switched to the third dehumidification heating mode in addition to the first dehumidification heating mode and the second dehumidification heating mode, thereby smoothly controlling the air outlet temperature TAV into the passenger compartment while maintaining the required dehumidification capacity.

[0084] In the heating mode, the control device 40 opens the first on-off valve 17 to open the second refrigerant passage 16, closes the bypass passage 22 with the second on-off valve 23, and throttles the first expansion valve 14. Furthermore, the second expansion valve 19 is fully closed, thereby preventing the refrigerant from flowing into the indoor evaporator 20. Then, the first expansion valve 14 is throttled. As a result, the control device 40 establishes a heating circulation path in which the refrigerant discharged from the compressor 11 flows through the indoor condenser 12, the first expansion valve 14, the outdoor heat exchanger 15, the first on-off valve 17, and the accumulator 21 in this order, and returns to the compressor 11, as shown by the black arrows in FIG. 1. In this heating circulation path, the outdoor heat exchanger 15 functions as an evaporator.

[0085] In the heating mode, similarly to the second dehumidification heating mode, the control device 40 controls the rotation speed of the compressor 11 so that the blown air temperature TAV into the passenger compartment approaches the target blown air temperature TAO, and closes the cool air bypass passage 35 with the air mix door 36.

[0086] The control device 40 controls the throttle opening of the first expansion valve 14 so that the degree of subcooling of the refrigerant flowing into the first expansion valve 14 approaches a predetermined target degree of subcooling so as to maximize the COP. The degree of subcooling of the refrigerant flowing into the first expansion valve 14 is calculated, for example, from the refrigerant temperature at the outlet of the indoor condenser 12 detected by a first temperature sensor 42 and the refrigerant pressure at the outlet of the indoor condenser 12 detected by a first pressure sensor 44.

[0087] As described above, in the heating mode, the interior condenser 12 dissipates heat from the high-pressure refrigerant discharged from the compressor 11 to the air, and the heater core 34 dissipates heat from the coolant to the air, so that the heated air can be blown into the vehicle cabin. This makes it possible to heat the vehicle cabin.

[0088] When switching from the first dehumidification and heating mode to the third dehumidification and heating mode, the control device 40 performs dryness fraction increase control as shown in the time chart of FIG.

[0089] In the dryness fraction increase control, the opening degree of the first expansion valve 14 is increased and the first on-off valve 17 is opened. Fig. 3 is a Mollier diagram showing the change in the state of the refrigerant in the refrigeration cycle apparatus 10 due to the dryness fraction increase control. The two-dot chain line in Fig. 3 shows the change in the state of the refrigerant in the refrigeration cycle apparatus 10 before the dryness fraction increase control is executed.

[0090] By increasing the opening degree of the first expansion valve 14, the dryness of the refrigerant at the inlet of the outdoor heat exchanger 15 increases, and the dryness of the refrigerant flowing into the outdoor heat exchanger 15 increases. Therefore, the liquid refrigerant inside the outdoor heat exchanger 15 decreases. This makes it possible to prevent a shortage of refrigerant circulating through the refrigerant circulation path in the third dehumidification heating mode.

[0091] By opening the first on-off valve 17, the outlet side of the outdoor heat exchanger 15 is connected to the low-pressure refrigerant circuit, so that the refrigerant inside the outdoor heat exchanger 15 is actively discharged and the liquid refrigerant inside the outdoor heat exchanger 15 is further reduced. This makes it possible to further prevent a shortage of refrigerant circulating through the refrigerant circulation path in the third dehumidification heating mode.

[0092] In the dryness fraction increase control, the controller 40 sets the throttle opening of the first expansion valve 14 to an opening degree or more that makes the dryness fraction of the refrigerant in the outdoor heat exchanger 15 equal to or greater than the lower dryness fraction Xmin. The controller 40 performs the dryness fraction increase control until the dryness fraction of the refrigerant in the outdoor heat exchanger 15 becomes equal to or greater than the lower dryness fraction Xmin.

[0093] The lower limit dryness Xmin is the dryness when the amount of refrigerant stored in the outdoor heat exchanger 15 (hereinafter referred to as the stored liquid refrigerant amount) becomes the upper limit stored amount Rmax. The upper limit stored amount Rmax is the amount of refrigerant determined so that the refrigerant does not become insufficient in the third dehumidification heating mode.

[0094] That is, as shown in Fig. 4, the upper limit storage amount Rmax is the amount of refrigerant that is obtained by subtracting the amount of refrigerant required in the third dehumidification heating mode from the amount of refrigerant sealed in the refrigeration cycle apparatus 10. Fig. 5 is a graph showing the correlation between the amount of stored refrigerant in the outdoor heat exchanger 15 of this embodiment and the dryness of the refrigerant (specifically, the average dryness).

[0095] In this way, the threshold value of the amount of refrigerant that may be stored in the outdoor heat exchanger 15 is determined by the amount of refrigerant charged in the refrigeration cycle device 10 and the amount of refrigerant required in the third dehumidification and heating mode (in other words, the operation mode to be switched to). On the other hand, the amount of refrigerant to be stored in the outdoor heat exchanger 15 is correlated with the average dryness in the outdoor heat exchanger 15 and the volume of the outdoor heat exchanger.

[0096] Therefore, the upper limit storage amount Rmax is determined from the amount of refrigerant charged in the refrigeration cycle device 10, and the upper limit storage amount Rmax is controlled to be equal to or greater than the lower limit dryness fraction Xmin, which is uniquely determined for the upper limit storage amount Rmax. This reliably prevents the refrigerant circulating through the refrigerant circulation path in the third dehumidification heating mode from becoming insufficient.

[0097] In this embodiment, the control device 40 performs the dryness fraction increase control when switching from the first dehumidification heating mode to the third dehumidification heating mode. The dryness fraction increase control is a control for increasing the dryness fraction of the refrigerant in the outdoor heat exchanger 15.

[0098] According to this, the liquid refrigerant inside the outdoor heat exchanger 15 decreases when switching from the first dehumidification heating mode to the third dehumidification heating mode, so that it is possible to prevent the liquid refrigerant from remaining in the outdoor heat exchanger 15 when switching from the first dehumidification heating mode to the third dehumidification heating mode. Therefore, it is possible to prevent a shortage of the refrigerant circulating in the refrigerant circulation path in the third dehumidification heating mode.

[0099] In this embodiment, the control device 40 controls the first on-off valve 17 to open the second refrigerant passage 16 when switching from the first dehumidification heating mode to the third dehumidification heating mode. By opening the first on-off valve 17, the outlet side of the outdoor heat exchanger 15 is connected to the second refrigerant passage 16 (in other words, the low-pressure refrigerant circuit), so that the refrigerant inside the outdoor heat exchanger 15 is actively discharged, and the liquid refrigerant inside the outdoor heat exchanger 15 is further reduced. This makes it possible to further prevent a shortage of refrigerant circulating through the refrigerant circulation path in the third dehumidification heating mode.

[0100] In this embodiment, in the dryness fraction increase control, the control device 40 sets the throttle opening of the first expansion valve 14 to an opening degree or more that makes the dryness fraction of the refrigerant in the outdoor heat exchanger 15 equal to or greater than the lower limit dryness fraction Xmin. This reliably prevents a shortage of refrigerant circulating through the refrigerant circulation path in the third dehumidification heating mode.

[0101] In the present embodiment, the control device 40 performs the dryness fraction increasing control until the dryness fraction of the refrigerant in the outdoor heat exchanger 15 becomes equal to or higher than the lower limit dryness fraction Xmin. This reliably prevents the refrigerant circulating through the refrigerant circulation path in the third dehumidification heating mode from becoming insufficient.

[0102] Second embodiment In the dryness fraction increase control of the above embodiment, the opening of the first expansion valve 14 is increased and the first on-off valve 17 is opened, whereas in the dryness fraction increase control of the present embodiment, as shown in the flowchart of FIG. 6, the rotation speed of the compressor 11 is reduced and the first on-off valve 17 is opened.

[0103] By reducing the rotation speed of the compressor 11, the flow rate of the refrigerant discharged from the compressor 11 decreases, and the flow rate of the refrigerant flowing into the first expansion valve 14 decreases, so that the opening degree of the first expansion valve 14 becomes relatively large. As a result, the dryness fraction of the refrigerant at the inlet of the outdoor heat exchanger 15 increases, and the dryness fraction of the refrigerant flowing into the outdoor heat exchanger 15 increases. Therefore, the liquid refrigerant inside the outdoor heat exchanger 15 decreases.

[0104] By opening the first on-off valve 17, the outlet side of the outdoor heat exchanger 15 is connected to the low-pressure refrigerant circuit, so that the refrigerant inside the outdoor heat exchanger 15 is actively discharged and the liquid refrigerant inside the outdoor heat exchanger 15 is further reduced. This makes it possible to prevent a shortage of refrigerant circulating through the refrigerant circulation path in the third dehumidification heating mode.

[0105] In the dryness fraction increase control of the present embodiment, it is preferable not to reduce the opening degree of the first expansion valve 14. This is to suppress a decrease in the dryness fraction of the refrigerant caused by reducing the opening degree of the first expansion valve 14.

[0106] Third embodiment In the above embodiment, in the dryness fraction increase control, the rotation speed of the compressor 11 is reduced and the first opening / closing valve 17 is opened. In the present embodiment, however, as shown in the flowchart of FIG. 7, in the dryness fraction increase control, the rotation speed of the compressor 11 is reduced and the opening degree of the second expansion valve 19 is increased without opening the first opening / closing valve 17.

[0107] By reducing the rotation speed of the compressor 11, the flow rate of the refrigerant discharged from the compressor 11 decreases, and the flow rate of the refrigerant flowing into the first expansion valve 14 decreases, so that the opening degree of the first expansion valve 14 becomes relatively larger. As a result, the dryness fraction of the refrigerant at the inlet of the outdoor heat exchanger 15 increases, and the dryness fraction of the refrigerant flowing into the outdoor heat exchanger 15 increases. Therefore, the liquid refrigerant inside the outdoor heat exchanger 15 decreases. This makes it possible to suppress a shortage of refrigerant circulating through the refrigerant circulation path in the third dehumidification heating mode.

[0108] By increasing the opening of the second expansion valve 19, the pressure on the outlet side of the outdoor heat exchanger 15 decreases, the refrigerant inside the outdoor heat exchanger 15 is actively discharged, and the liquid refrigerant inside the outdoor heat exchanger 15 is further reduced. This makes it possible to further prevent a shortage of refrigerant circulating through the refrigerant circulation path in the third dehumidification heating mode.

[0109] (Fourth embodiment) As shown in FIG. 8, the refrigeration cycle device 10 of the present embodiment includes a fourth refrigerant passage 26, a third expansion valve 27, and a chiller .

[0110] The fourth refrigerant passage 26 is connected in parallel to the third refrigerant passage 18 to the outlet side of the outdoor heat exchanger 15. The fourth refrigerant passage 26 is a refrigerant passage that guides the refrigerant flowing out of the outdoor heat exchanger 15 to the inlet side of the indoor evaporator 20.

[0111] A third expansion valve 27 configured to be able to change the passage area of ​​the fourth refrigerant passage 26 is disposed in the fourth refrigerant passage 26. The third expansion valve 27 is an electric variable throttling mechanism similar to the first expansion valve 14, and increases or decreases the throttling opening of the third expansion valve 27 according to a control signal output from the control device 40. Specifically, the third expansion valve 27 reduces the pressure of the refrigerant passing through it according to its throttling opening, thereby decompressing and expanding the refrigerant. When fully open, the third expansion valve 27 allows the refrigerant to pass through without reducing the pressure and expanding it. When fully closed, the third expansion valve 27 blocks the flow of the refrigerant.

[0112] The outlet side of the third expansion valve 27 is connected to the inlet side of the chiller 28. The chiller 28 is a battery cooler that cools the battery mounted on the vehicle. A refrigerant flows through the chiller 28, for example, in a battery cooling mode and a battery cooling and heating mode. The chiller 28 is an evaporator that evaporates the refrigerant flowing therethrough by the heat of the battery, thereby exerting a heat absorbing effect to cool the battery. The outlet side of the interior evaporator 20 is connected to the inlet side of the accumulator 21.

[0113] The refrigeration cycle device 10 can execute a battery cooling mode and a heating / battery cooling mode in addition to the cooling mode, the first dehumidification heating mode, the second dehumidification heating mode, the third dehumidification heating mode, and the heating mode similar to those in the above embodiment.

[0114] In the battery cooling mode, the control device 40 closes the second refrigerant passage 16 with the first on-off valve 17, closes the bypass passage 22 with the second on-off valve 23, fully opens the first expansion valve 14, and fully closes the second expansion valve 19 to prevent the refrigerant from flowing into the evaporator 20. As a result, the control device 40 establishes a cooling circulation path in which the refrigerant discharged from the compressor 11 flows through the indoor condenser 12, the first expansion valve 14, the outdoor heat exchanger 15, the check valve 24, the third expansion valve 27, and the chiller 28 in this order, before returning to the compressor 11, as shown by the outlined arrow in Fig. 8.

[0115] In the battery cooling mode, the control device 40 stops the blower 32. As a result, the refrigerant that has flowed into the interior condenser 12 flows out of the interior condenser 12 with almost no heat exchange with the air.

[0116] As described above, in the battery cooling mode, the exterior heat exchanger 15 functions as a condenser, and the chiller 28 functions as an evaporator, thereby achieving cooling of the battery.

[0117] In the heating / battery cooling mode, the control device 40 shuts off the second refrigerant passage 16 with the first on-off valve 17, shuts off the bypass passage 22 with the second on-off valve 23, fully closes the first expansion valve 14 to prevent the refrigerant from flowing into the outdoor heat exchanger 15, and fully closes the second expansion valve 19 to prevent the refrigerant from flowing into the evaporator 20. As a result, the control device 40 establishes a cooling circulation path in which the refrigerant discharged from the compressor 11 flows through the indoor condenser 12, the third expansion valve 27, and the chiller 28 in this order, and then returns to the compressor 11, as shown by the black arrow in Fig. 8.

[0118] As described above, in the cooling mode, the heat of the high-pressure refrigerant discharged from the compressor 11 is dissipated to the air in the interior condenser 12, and heat is absorbed from the battery in the chiller 28. This makes it possible to heat the vehicle interior and cool the battery.

[0119] When switching from the battery cooling mode to the third dehumidification heating mode, the dryness fraction increase control is performed similarly to the first embodiment.When switching from the battery cooling mode to the battery cooling heating mode, the dryness fraction increase control is performed similarly to the first embodiment.

[0120] That is, when switching from an operation mode in which the outdoor heat exchanger 15 functions as a condenser to an operation mode in which the refrigerant does not flow into the outdoor heat exchanger 15, the dryness fraction increase control is performed.

[0121] By increasing the opening degree of the first expansion valve 14, the dryness of the refrigerant at the inlet of the outdoor heat exchanger 15 increases, and the dryness of the refrigerant flowing into the outdoor heat exchanger 15 increases. Therefore, the amount of liquid refrigerant inside the outdoor heat exchanger 15 decreases. This makes it possible to prevent a shortage of refrigerant circulating through the refrigerant circulation path in the battery cooling heating mode.

[0122] By opening the first on-off valve 17, the outlet side of the outdoor heat exchanger 15 is connected to the low-pressure refrigerant circuit, so that the refrigerant inside the outdoor heat exchanger 15 is actively discharged and the liquid refrigerant inside the outdoor heat exchanger 15 is further reduced. This makes it possible to further prevent a shortage of refrigerant circulating through the refrigerant circulation path in the battery cooling and heating mode.

[0123] Fifth embodiment In this embodiment, as shown in FIG. 9, the arrangement of the first expansion valve 14, the outdoor heat exchanger 15, the second expansion valve 19, the indoor evaporator 20, the third expansion valve 27 and the chiller 28 is changed from that of the above-described fourth embodiment.

[0124] The second expansion valve 19 and the indoor evaporator 20 are disposed in series upstream of the first expansion valve 14 and the outdoor heat exchanger 15 in the refrigerant flow, and are disposed in parallel with the third expansion valve 27 and the chiller 28.

[0125] An outlet-side bypass passage 29 is connected to the refrigerant outlet side of the indoor evaporator 20. The outlet-side bypass passage 29 is a refrigerant passage that guides the refrigerant flowing out from the indoor evaporator 20 to the suction side of the compressor 11, bypassing the first expansion valve 14 and the outdoor heat exchanger 15.

[0126] A bypass on-off valve 60 is disposed in the outlet-side bypass passage 29. The bypass on-off valve 60 is a solenoid valve that opens and closes the outlet-side bypass passage 29. The bypass on-off valve 60 is a refrigerant path switching unit that switches the refrigerant path. The operation of the bypass on-off valve 60 is controlled by a control signal output from the control device 40. When the control device 40 opens the bypass on-off valve 60, the refrigerant that flows out of the indoor evaporator 20 can bypass the outdoor heat exchanger 15 and be sucked into the compressor 11.

[0127] The refrigeration cycle apparatus 10 can operate in a heating mode and a waste heat recovery mode.

[0128] In the heating mode, the control device 40 shuts off the outlet side bypass passage 29 with the bypass on-off valve 60 and fully closes the third expansion valve 27 to prevent the refrigerant from flowing into the chiller 28. As a result, the control device 40 establishes a refrigerant circulation path in which the refrigerant discharged from the compressor 11 flows through the indoor condenser 12, the second expansion valve 19, the indoor evaporator 20, the first expansion valve 14, and the outdoor heat exchanger 15 in this order, and then returns to the compressor 11, as shown by the outlined arrow in FIG.

[0129] As described above, in the heating mode, the exterior heat exchanger 15 functions as an evaporator, and the interior evaporator 20 functions as a condenser, so that the air heated by the interior evaporator 20 can be blown into the vehicle interior. This makes it possible to heat the vehicle interior.

[0130] In the waste heat recovery mode, the control device 40 fully closes the second expansion valve 19 to prevent the refrigerant from flowing into the indoor evaporator 20 and the outdoor heat exchanger 15. As a result, the control device 40 establishes a refrigerant circulation path in which the refrigerant discharged from the compressor 11 flows through the indoor condenser 12, the third expansion valve 27, and the chiller 28 in this order, and then returns to the compressor 11, as shown by the black arrows in Fig. 9.

[0131] As described above, in the waste heat recovery mode, the inflow of refrigerant into the interior evaporator 20 is prevented, and heat can be absorbed from the battery by the chiller 28. This makes it possible to realize waste heat recovery from the battery.

[0132] When switching from the heating mode to the waste heat recovery mode, the dryness fraction increase control is performed in the same manner as in the first embodiment. That is, when switching from an operation mode in which the indoor evaporator 20 functions as a condenser to an operation mode in which the refrigerant does not flow into the indoor evaporator 20, the dryness fraction increase control is performed.

[0133] By increasing the opening degree of the second expansion valve 19, the dryness of the refrigerant at the inlet of the indoor evaporator 20 increases, and the dryness of the refrigerant flowing into the indoor evaporator 20 increases. Therefore, the liquid refrigerant inside the indoor evaporator 20 decreases. This makes it possible to prevent a shortage of refrigerant circulating through the refrigerant circulation path in the waste heat recovery mode.

[0134] By opening the bypass on-off valve 60, the outlet side of the indoor evaporator 20 is connected to the low-pressure refrigerant circuit (specifically, the outlet-side bypass passage 29), so that the refrigerant inside the indoor evaporator 20 is actively discharged, and the liquid refrigerant inside the indoor evaporator 20 is further reduced. This makes it possible to further prevent a shortage of refrigerant circulating through the refrigerant circulation path in the waste heat recovery mode.

[0135] Sixth embodiment A refrigeration cycle device 10 of this embodiment is shown in FIG.

[0136] An inlet side of a first three-way joint 61a having three inlet and outlet ports that communicate with each other is connected to the outlet side of the indoor condenser 12. As such a three-way joint, one formed by joining a plurality of pipes or one formed by providing a plurality of refrigerant passages in a metal block or a resin block can be used.

[0137] The refrigeration cycle 10 includes a second three-way joint 61b, a third three-way joint 61c, a fourth three-way joint 61d, a fifth three-way joint 61e, a sixth three-way joint 61f, a seventh three-way joint 61g, and an eighth three-way joint 61h. The basic configurations of the second three-way joint 61b to the eighth three-way joint 61h are all similar to that of the first three-way joint 61a.

[0138] The first three-way joint 61a to the eighth three-way joint 61h function as a branching section that branches the flow of refrigerant that has flowed in from one inlet when one of the three inlet / outlets is used as an inlet and two are used as outlets. The first three-way joint 61a to the eighth three-way joint 61h function as a merging section that merges the flows of refrigerant that have flowed in from the two inlets when two of the three inlet / outlets are used as inlets and one is used as an outlet.

[0139] In this embodiment, the first three-way joint 61a, the third three-way joint 61c, the sixth three-way joint 61f, and the seventh three-way joint 61g are connected to function as a branching section, and the second three-way joint 61b, the fourth three-way joint 61d, the fifth three-way joint 61e, and the eighth three-way joint 61h are connected to function as a merging section.

[0140] One outlet of the first three-way joint 61a is connected to the inlet side of the receiver 63 via a first on-off valve 62 and a fifth three-way joint 61e. The other outlet of the first three-way joint 61a is connected to the inlet side of the first expansion valve 14 via a second on-off valve 64 and a second three-way joint 61b.

[0141] The first on-off valve 62 is a solenoid valve that opens and closes an inlet-side passage 65a that extends from one outlet of the first three-way joint 61a to the inlet of the receiver 63. The first on-off valve 62 is a refrigerant path switching unit that switches the refrigerant path. The opening and closing operation of the first on-off valve 62 is controlled by a control voltage output from the control device 40.

[0142] The fifth three-way joint 61e has one inlet connected to the outlet side of the first on-off valve 62 in the inlet-side passage 65a. One outlet of the fifth three-way joint 61e is connected to the inlet side of the receiver 63 in the inlet-side passage 65a.

[0143] The receiver 63 is a liquid storage section having a gas / liquid separation function. The receiver 63 separates the gas and liquid of the refrigerant flowing out from the heat exchange section functioning as a condenser that condenses the refrigerant in the refrigeration cycle 10. The receiver 63 causes a part of the separated liquid-phase refrigerant to flow downstream and stores the remaining liquid-phase refrigerant as surplus refrigerant in the cycle.

[0144] The second on-off valve 64 is a solenoid valve that opens and closes an outside air side passage 65b that leads from the other outlet of the first three-way joint 61a to one inlet of the second three-way joint 61b. The second on-off valve 64 is a refrigerant path switching unit that switches the refrigerant path. The basic configuration of the second on-off valve 64 is the same as that of the first on-off valve 62. The opening and closing operation of the second on-off valve 64 is also controlled by a control voltage output from the control device 40.

[0145] The other inlet of the second three-way joint 61b is connected to the refrigerant outlet side of the receiver 63. A sixth three-way joint 61f and a first check valve 66a are disposed in an outlet-side passage 65c that connects the refrigerant outlet of the receiver 63 and the other inlet of the second three-way joint 61b.

[0146] The inlet of the sixth three-way joint 61f is connected to the refrigerant outlet side of the receiver 63 via an outlet-side passage 65c. The other inlet of the second three-way joint 61b is connected to one outlet of the sixth three-way joint 61f via an outlet-side passage 65c and a first check valve 66a. The other outlet of the sixth three-way joint 61f is connected to the inlet side of a seventh three-way joint 61g.

[0147] The outlet of the second three-way joint 61b is connected to the refrigerant inlet side of the outdoor heat exchanger 15 via the first expansion valve 14. The refrigerant outlet of the outdoor heat exchanger 15 is connected to the inlet side of the third three-way joint 61c.

[0148] One of the outlets of the third three-way joint 61c is connected to one of the inlet sides of the fourth three-way joint 61d via a third on-off valve 67. The third on-off valve 67 is an electromagnetic valve that opens and closes a suction side passage 65d that leads from one of the outlets of the third three-way joint 61c to one of the inlet sides of the fourth three-way joint 61d. The third on-off valve 67 is a refrigerant path switching unit that switches the refrigerant path. The opening and closing operation of the third on-off valve 67 is controlled by a control voltage output from the control device 40.

[0149] The outlet of the fourth three-way joint 61d is connected to the suction port side of the compressor 11. The other outlet of the third three-way joint 61c is connected to the other inlet side of the fifth three-way joint 61e via a second check valve 66b.

[0150] The second check valve 66b is disposed in a refrigerant passage extending from the other outlet of the third three-way joint 61c to the other inlet of the fifth three-way joint 61e. The second check valve 66b allows the refrigerant to flow from the refrigerant outlet side of the outdoor heat exchanger 15 to the inlet side of the receiver 63 via the third three-way joint 61c, but prohibits the refrigerant from flowing from the receiver 63 to the refrigerant outlet side of the outdoor heat exchanger 15.

[0151] The third on-off valve 67 can adjust the flow rate of the refrigerant that flows out of the exterior heat exchanger 15 and is caused to flow into the receiver 63 and the flow rate of the refrigerant that flows directly into the compressor 11.

[0152] The other outlet of the sixth three-way joint 61f disposed in the outlet-side passage 65c is connected to the inlet side of the seventh three-way joint 61g. The other inlet of the second three-way joint 61b is connected to one outlet of the sixth three-way joint 61f via a first check valve 66a.

[0153] The first check valve 66a allows the refrigerant to flow from the refrigerant outlet side of the receiver 63 to the first expansion valve 14, and prohibits the refrigerant from flowing to the receiver 63 from the second three-way joint 61b side.

[0154] An inlet side of the second expansion valve 19 is connected to one outlet of the seventh three-way joint 61g. Moreover, an inlet side of the third expansion valve 27 is connected to the other outlet of the seventh three-way joint 61g.

[0155] The outlet of the second expansion valve 19 is connected to the refrigerant inlet side of the indoor evaporator 20. One inlet of an eighth three-way joint 61h is connected to the refrigerant outlet of the indoor evaporator 20 via a third check valve 66c. The third check valve 66c allows the refrigerant to flow from the refrigerant outlet side of the indoor evaporator 20 to the eighth three-way joint 61h, and prohibits the refrigerant from flowing from the eighth three-way joint 61h to the indoor evaporator 20.

[0156] The outlet of the third expansion valve 27 is connected to the inlet side of the refrigerant passage 24a of the chiller 28. The other inlet of the eighth three-way joint 61h is connected to the refrigerant outlet side of the chiller 28. The suction port side of the compressor 11 is connected to the outlet of the eighth three-way joint 61h via the fourth three-way joint 61d.

[0157] As is clear from the above description, in the refrigeration cycle 10, the first on-off valve 62, the second on-off valve 64, and the third on-off valve 67 open and close the refrigerant passage, thereby making it possible to switch the refrigerant circuit.

[0158] The refrigeration cycle device 10 can execute a cooling / dehumidification heating mode, a battery cooling mode, a dehumidification heating mode, and a heating / battery cooling mode by switching the refrigerant circuit.

[0159] In the cooling / dehumidifying heating mode, the control device 40 shuts off the inlet side passage 65a with the first on-off valve 62, opens the second on-off valve 64 to open the outdoor air side passage 65b, fully opens the first expansion valve 14, and fully closes the third expansion valve 27 to prevent the refrigerant from flowing into the chiller 28. As a result, the control device 40 establishes a refrigerant circulation path in which the refrigerant discharged from the compressor 11 flows through the indoor condenser 12, the first expansion valve 14, the outdoor heat exchanger 15, the second check valve 66b, the receiver 63, the second expansion valve 19, and the indoor evaporator 20 in this order, and then returns to the compressor 11, as shown by the outlined arrow in FIG.

[0160] As described above, in the cooling / dehumidifying heating mode, the exterior heat exchanger 15 functions as a condenser, and the air cooled and dehumidified by the interior evaporator 20 can be blown into the vehicle interior. This allows the vehicle interior to be cooled or dehumidified and heated.

[0161] In the battery cooling mode, the control device 40 shuts off the inlet side passage 65a with the first on-off valve 62, opens the second on-off valve 64 to open the outdoor air side passage 65b, fully opens the first expansion valve 14, and fully closes the second expansion valve 19 to prevent the refrigerant from flowing into the indoor evaporator 20. As a result, the control device 40 establishes a refrigerant circulation path in which the refrigerant discharged from the compressor 11 flows through the indoor condenser 12, the first expansion valve 14, the outdoor heat exchanger 15, the second check valve 66b, the receiver 63, the third expansion valve 27, and the chiller 28 in this order, before returning to the compressor 11, as shown by the black arrows in FIG.

[0162] In the battery cooling mode, the control device 40 stops the blower 32. As a result, the refrigerant that has flowed into the interior condenser 12 flows out of the interior condenser 12 with almost no heat exchange with the air.

[0163] As described above, in the battery cooling mode, the exterior heat exchanger 15 functions as a condenser, and the chiller 28 functions as an evaporator, thereby achieving cooling of the battery.

[0164] In the battery cooling mode, the control device 40 shuts off the inlet side passage 65a with the first on-off valve 62, opens the second on-off valve 64 to open the outdoor air side passage 65b, fully opens the first expansion valve 14, and fully closes the third expansion valve 27 to prevent the refrigerant from flowing into the chiller 28. As a result, the control device 40 establishes a refrigerant circulation path in which the refrigerant discharged from the compressor 11 flows through the indoor condenser 12, the first expansion valve 14, the outdoor heat exchanger 15, the second check valve 66b, the receiver 63, the second expansion valve 19, and the indoor evaporator 20 in this order, before returning to the compressor 11, as shown by the outlined arrow in FIG.

[0165] As described above, in the dehumidifying and heating mode, the outdoor heat exchanger 15 functions as a condenser, and the chiller 28 functions as an evaporator, thereby achieving cooling of the battery.

[0166] In the dehumidifying and heating mode, the controller 40 opens the first on-off valve 62 to open the inlet side passage 65a, closes the outside air side passage 65b with the second on-off valve 64, fully opens the first expansion valve 14, and fully closes the third expansion valve 27 to prevent refrigerant from flowing into the chiller 28. In this way, the controller 40 establishes a refrigerant circulation path in which the refrigerant discharged from the compressor 11 flows through the indoor condenser 12, the receiver 63, the second expansion valve 19, and the indoor evaporator 20 in this order, and then returns to the compressor 11, as shown by the outlined horizontal arrow in Fig. 10.

[0167] As described above, in the dehumidifying and heating mode, the inflow of refrigerant into the exterior heat exchanger 15 is prevented, and the air that has been cooled and dehumidified by the interior evaporator 20 can be blown into the vehicle cabin. This allows the dehumidifying and heating of the vehicle cabin to be achieved.

[0168] In the heating battery cooling mode, the control device 40 opens the first on-off valve 62 to open the inlet side passage 65a, closes the outside air side passage 65b with the second on-off valve 64, fully opens the first expansion valve 14, and fully closes the second expansion valve 19 to prevent the refrigerant from flowing into the indoor evaporator 20. As a result, the control device 40 establishes a refrigerant circulation path in which the refrigerant discharged from the compressor 11 flows through the indoor condenser 12, the receiver 63, the third expansion valve 27, and the chiller 28 in this order, and then returns to the compressor 11, as shown by the outlined diagonal line arrow in Fig. 10.

[0169] As described above, in the dehumidifying and heating mode, the inflow of refrigerant into the exterior heat exchanger 15 is prevented, and the air that has been cooled and dehumidified by the interior evaporator 20 can be blown into the vehicle cabin. This allows the dehumidifying and heating of the vehicle cabin to be achieved.

[0170] When switching from the cooling / dehumidifying heating mode or the battery cooling mode to the dehumidifying heating mode or the heating / battery cooling mode, the control device 40 performs dryness fraction increase control similar to that of the above embodiment.

[0171] That is, when switching from an operation mode in which the outdoor heat exchanger 15 functions as a condenser to an operation mode in which the refrigerant does not flow into the outdoor heat exchanger 15, the dryness fraction increase control is performed.

[0172] By increasing the opening degree of the first expansion valve 14, the dryness of the refrigerant at the inlet of the outdoor heat exchanger 15 increases, and the dryness of the refrigerant flowing into the outdoor heat exchanger 15 increases. Therefore, the liquid refrigerant inside the outdoor heat exchanger 15 decreases. This makes it possible to prevent a shortage of refrigerant circulating through the refrigerant circulation path in the dehumidification heating mode and the heating battery cooling mode.

[0173] By opening the third on-off valve 67, the outlet side of the outdoor heat exchanger 15 is connected to the low-pressure refrigerant circuit (specifically, the suction side passage 65d), so that the refrigerant inside the outdoor heat exchanger 15 is actively discharged, and the liquid refrigerant inside the outdoor heat exchanger 15 is further reduced. This makes it possible to prevent a shortage of refrigerant circulating through the refrigerant circulation path in the dehumidification heating mode and the heating battery cooling mode.

[0174] (Other embodiments) The above embodiment can be modified in various ways as follows: The configurations of the respective embodiments may be appropriately combined.

[0175] (1) In the above embodiment, the refrigeration cycle device 10 includes the indoor condenser 12 that exchanges heat between the high-pressure refrigerant discharged from the compressor 11 and the air blown into the vehicle cabin. However, instead of the indoor condenser 12, the refrigeration cycle device 10 may include a condenser that exchanges heat between the high-pressure refrigerant discharged from the compressor 11 and the cooling water in the high-temperature cooling water circuit and the air, and a heater core that exchanges heat between the cooling water heated by the condenser and the air blown into the vehicle cabin.

[0176] (2) In the above fourth embodiment, the refrigeration cycle device 10 is equipped with a chiller 28 that evaporates the refrigerant using heat from the battery, but the chiller 28 may be configured to exchange heat between the refrigerant, the cooling water in the low-temperature cooling water circuit, and air, and to cool the battery with the cooling water cooled by the chiller 28.

[0177] (3) In the above embodiment, the operation mode of the vehicle air conditioner is switched to the heating mode when the air conditioner switch is off, and is switched to the cooling mode or the dehumidifying heating mode when the air conditioner switch is on, but the switching of the operation mode is not limited to this. For example, an operation mode setting switch for setting each operation mode may be provided on the operation panel, and the heating mode, the cooling mode, and the dehumidifying heating mode may be switched in response to an operation signal of the operation mode setting switch.

[0178] (4) The various on-off valves 17, 23, 60, 62, 64, and 67 in the above embodiments may be three-way valves provided at branching points of the refrigerant passages. The three-way valves are electric three-way flow control valves that have one inlet and two outlets and can adjust the passage area ratio of the two outlets. The operation of the three-way valves is controlled by a control signal output from the control device 40.

[0179] (5) Although the refrigeration cycle apparatus 10 of the above embodiment is used for air conditioning of a vehicle and cooling of a battery, the application of the refrigeration cycle apparatus 10 is not limited to this.

[0180] For example, the cooling water cooled by the refrigeration cycle device 10 may be used to cool various devices to be cooled, such as an inverter, a driving motor, etc. The refrigeration cycle device 10 may be applied to a stationary air conditioner, a freezing and refrigeration device, etc. [Explanation of symbols]

[0181] 11 Compressor 12 Indoor condenser (first condenser) 14 First expansion valve 15 Outdoor heat exchanger (second condenser) 16 Second refrigerant passage (low pressure refrigerant passage) 17 First opening and closing valve (refrigerant path switching section) 19 Second expansion valve 20 Indoor evaporator (evaporator) 23 Second opening / closing valve (refrigerant path switching section) 40 Control device (control unit)

Claims

1. A compressor (11) that compresses and discharges a refrigerant; a first condenser (12) and a second condenser (15) for condensing the refrigerant by heat exchange; an evaporator (20) that evaporates the refrigerant by heat exchange; a first expansion valve (14) for reducing the pressure of the refrigerant flowing into the second condenser and expanding the refrigerant; a second expansion valve (19) for reducing the pressure and expanding the refrigerant flowing into the evaporator; a refrigerant path switching unit (17, 23) that switches between a first circulation path in which the refrigerant circulates through the compressor, the first condenser, the first expansion valve, the second condenser, the second expansion valve, the evaporator, and the compressor in this order, and a second circulation path in which the refrigerant circulates through the compressor, the first condenser, the second expansion valve, the evaporator, and the compressor in this order; a control unit (40) that performs a dryness increase control for increasing the dryness of the refrigerant in the second condenser when switching from the first circulation path to the second circulation path.

2. A compressor (11) that compresses and discharges a refrigerant; a first condenser (12) and a second condenser (15) for condensing the refrigerant by heat exchange; an evaporator (20) that evaporates the refrigerant by heat exchange; a first expansion valve (14) for reducing the pressure of the refrigerant flowing into the second condenser and expanding the refrigerant; a second expansion valve (19) for reducing the pressure and expanding the refrigerant flowing into the evaporator; a low-pressure refrigerant passage (16) that guides the refrigerant flowing out of the second condenser to a suction side of the compressor, bypassing the second expansion valve and the evaporator; a refrigerant path switching unit (17, 23) that switches between a first circulation path in which the refrigerant circulates through the compressor, the first condenser, the first expansion valve, the second condenser, the second expansion valve, the evaporator, and the compressor in this order, and a second circulation path in which the refrigerant circulates through the compressor, the first condenser, the second expansion valve, the evaporator, and the compressor in this order, and opens and closes the low-pressure refrigerant path; a control unit (40) that controls the refrigerant path switching unit so that the low-pressure refrigerant passage is opened when switching from the first circulation path to the second circulation path.

3. The refrigeration cycle apparatus according to claim 2 , wherein the control unit performs a dryness increase control for increasing a dryness of the refrigerant in the second condenser when switching from the first circulation path to the second circulation path.

4. 4. The refrigeration cycle apparatus according to claim 1, wherein the dryness fraction increase control is a control for increasing a throttle opening degree of the first expansion valve.

5. The dryness fraction increase control is a control for increasing the throttle opening of the first expansion valve to an opening degree at which the dryness fraction of the refrigerant in the second condenser is equal to or greater than a lower limit dryness fraction (Xmin), The lower limit dryness is a dryness at which the amount of the refrigerant stored in the second condenser is equal to or less than an upper limit storage amount (Rmax), The refrigeration cycle apparatus according to claim 4 , wherein the upper limit storage amount is a refrigerant amount that is set so that the refrigerant does not become insufficient in the second circulation path.

6. The control unit performs the dryness fraction increase control until the dryness fraction of the refrigerant in the second condenser becomes equal to or greater than a lower limit dryness fraction (Xmin), The lower limit dryness is a dryness at which the amount of the refrigerant stored in the second condenser is equal to or less than an upper limit storage amount (Rmax), 6. The refrigeration cycle apparatus according to claim 1, wherein the upper limit storage amount is a refrigerant amount determined so that the refrigerant does not run short in the second circulation path.

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