Refrigeration cycle device

Abstract

To suppress frosting of one of evaporators even during transient load fluctuations or the like.SOLUTION: A refrigeration cycle device comprises: a second pressure reduction unit 19 that is disposed in parallel to a first pressure reduction unit in the flow of a refrigerant and reduces the pressure of the refrigerant whose heat is dissipated in a radiator; a second evaporator 20 for reducing the pressure of the refrigerant whose pressure is reduced in the second pressure reduction unit; an opening adjustment unit 25 for adjusting the opening of a refrigerant flow passage that is parallel to the first evaporator and on a downstream side of the second evaporator; and a control unit 40 for controlling the openings of the first pressure reduction unit and the opening adjustment unit. The control unit performs frosting suppression control of, during normal control, setting the opening of the second pressure reduction unit to an opening above a first predetermined opening and controlling the opening of the opening adjustment unit to an opening above a second predetermined opening, and when the temperature of the second evaporator becomes equal to or lower than a predetermined temperature Te1, which is the temperature associated with the occurrence of frosting in the second evaporator, setting the opening of the second pressure reduction unit to the first predetermined opening or less and setting the opening of the opening adjustment section to the second predetermined opening or less.SELECTED DRAWING: Figure 8

Description

[Technical field]

[0001] The present invention relates to a refrigeration cycle device including two evaporators. [Background technology]

[0002] Conventionally, Patent Document 1 discloses a refrigeration cycle device including two evaporators arranged in parallel with each other in the flow of refrigerant, and a constant pressure valve arranged on the outlet side of one of the evaporators.

[0003] The constant pressure valve is a mechanical variable throttle mechanism that maintains the pressure of the refrigerant at the outlet side of one of the evaporators at a predetermined value. The constant pressure valve prevents the refrigerant evaporation temperature of one of the evaporators from dropping below freezing point and causing frost. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent No. 5929372 Summary of the Invention [Problem to be solved by the invention]

[0005] In this conventional technology, the constant pressure valve prevents the refrigerant evaporation temperature of one of the evaporators from dropping below freezing. However, during transient load fluctuations, the refrigerant evaporation temperature of one of the evaporators may drop below freezing, causing frost to form.

[0006] Therefore, in order to suppress such a decrease in the refrigerant evaporation temperature in one of the evaporators, it is possible to consider blocking the flow of refrigerant flowing into one of the evaporators by using a valve arranged on the inlet side of the one of the evaporators.

[0007] However, even if the flow of refrigerant into one of the evaporators is blocked, the refrigerant pressure in one evaporator will be equalized with the refrigerant pressure in the other evaporator via the constant pressure valve on the outlet side, and the temperature of the refrigerant in one evaporator will eventually drop below freezing.

[0008] In view of the above, an object of the present invention is to prevent one of the evaporators from frosting even during a transient load change or the like. [Means for solving the problem]

[0009] In order to achieve the above object, the refrigeration cycle device of the present invention comprises: a compressor (11) that draws in, compresses, and discharges a refrigerant; a radiator (12) that radiates heat from a refrigerant discharged from the compressor; a first pressure reducing section (14) that reduces the pressure of the refrigerant whose heat has been radiated by the radiator; a first evaporator (15) that reduces the pressure of the refrigerant reduced in pressure by the first pressure reduction section; a second pressure reducing section (19) that is arranged in parallel with the first pressure reducing section in the flow of the refrigerant and reduces the pressure of the refrigerant whose heat has been radiated by the radiator; a second evaporator (20) that reduces the pressure of the refrigerant reduced in pressure by the second pressure reduction section; an opening adjustment unit (25) that adjusts an opening of a refrigerant flow path that is parallel to the first evaporator and downstream of the second evaporator; a control unit (40) that controls the opening degree of the first pressure reducing unit and the opening degree adjusting unit, The control unit During normal control, the opening degree of the second pressure reducing unit is controlled to be greater than the first predetermined opening degree, and the opening degree of the opening degree adjustment unit is controlled to be greater than the second predetermined opening degree, When the temperature of the second evaporator falls below a predetermined temperature (Te1) which is a temperature related to the occurrence of frost in the second evaporator, frost suppression control is performed in which the opening degree of the second pressure reduction section is set to a first predetermined opening degree or less and the opening degree of the opening adjustment section is set to a second predetermined opening degree or less.

[0010] According to this, in the frost prevention control, the flow rate of refrigerant supplied to the second evaporator is reduced by setting the opening degree of the second pressure reduction section to a first predetermined opening degree or less, and the opening degree of the opening degree adjustment section to a second predetermined opening degree or less is pressure equalized from the downstream side of the second evaporator, thereby suppressing a pressure drop (in other words, a temperature drop).

[0011] Therefore, when the flow rate of the refrigerant supplied to the second evaporator is reduced in the second pressure reducing section in order to suppress frosting of the second evaporator, a decrease in the pressure of the refrigerant in the second evaporator can be suppressed, so that frosting of the second evaporator can be suppressed even during transient load fluctuations, etc.

[0012] In addition, the reference numerals in parentheses next to each means described in this section and in the claims indicate the correspondence with the specific means described in the embodiments described later. [Brief description of the drawings]

[0013] [Figure 1] 1 is a schematic configuration diagram of a vehicle air conditioner according to a first embodiment. [Diagram 2] 3 is a flowchart showing a flow of a control process executed by a control device of the vehicle air conditioner in the first embodiment. [Diagram 3] FIG. 2 is a Mollier diagram showing a state of a refrigerant in a first dehumidification heating mode (first mode) in the refrigeration cycle device of the first embodiment. [Figure 4] FIG. 3 is a Mollier diagram showing the state of a refrigerant in a first dehumidification heating mode (second mode) in the refrigeration cycle device of the first embodiment. [Diagram 5] FIG. 4 is a Mollier diagram showing the state of a refrigerant in a first dehumidification heating mode (third mode) in the refrigeration cycle device of the first embodiment. [Figure 6] FIG. 4 is a Mollier diagram showing the state of a refrigerant in a first dehumidification heating mode (fourth mode) in the refrigeration cycle device of the first embodiment. [Figure 7] FIG. 4 is a Mollier diagram showing a state of a refrigerant in a second dehumidification heating mode in the refrigeration cycle device of the first embodiment. [Figure 8] 5 is a time chart showing a control example of frost suppression control in the refrigeration cycle device of the first embodiment. [Figure 9] FIG. 11 is a schematic cross-sectional view of a motor-operated valve according to a second embodiment. [Figure 10] FIG. 11 is a partially enlarged view of a motor-operated valve in a first example of a second embodiment. [Figure 11] FIG. 11 is a partially enlarged view of a motor-operated valve in a second example of the second embodiment. [Figure 12] FIG. 11 is a partially enlarged view of a motor-operated valve in a third example of the second embodiment. [Figure 13] 13 is a time chart showing an example of control of the motor-operated valve in the refrigeration cycle device of the third embodiment. [Figure 14] FIG. 11 is a schematic configuration diagram of a vehicle air conditioner according to a fourth embodiment. [Figure 15] 13 is a Mollier diagram comparing cooling states during normal control and during high battery cooling control of the vehicle air conditioner in the fourth embodiment. FIG. [Figure 16] 13 is an explanatory diagram comparing cooling temperatures during normal control and during high battery cooling control in a vehicle air conditioner in the fourth embodiment. FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0014] (First embodiment) FIG. 1 is a schematic configuration diagram of a vehicle air conditioner 1 according to this embodiment.

[0015] In this embodiment, the refrigeration cycle device 10 of the present invention is applied to a vehicle air conditioner 1 of a hybrid vehicle that obtains driving force for running the vehicle from an internal combustion engine and a running electric motor. In the vehicle air conditioner 1, the refrigeration cycle device 10 performs a function of cooling or heating the air blown into the vehicle cabin, which is the space to be air-conditioned.

[0016] For this reason, the refrigeration cycle device 10 is configured to be able to switch between a refrigerant flow path for a cooling mode (cooling operation) that cools the interior of the vehicle cabin, a refrigerant flow path for a dehumidification heating mode (dehumidification operation) that heats the interior of the vehicle cabin while dehumidifying it, and a refrigerant flow path for a heating mode (heating operation) that heats the interior of the vehicle cabin.

[0017] Furthermore, in the refrigeration cycle apparatus 10, as the dehumidifying and heating mode, a first dehumidifying and heating mode that is normally performed, and a second dehumidifying and heating mode that is performed when the outside air temperature is extremely low, etc., can be performed.

[0018] In addition, the refrigeration cycle device 10 of this embodiment uses a normal fluorocarbon refrigerant as the refrigerant, and configures a subcritical refrigeration cycle in which the pressure of the high-pressure refrigerant does not exceed the critical pressure of the refrigerant. Refrigeration oil for lubricating the compressor 11 is mixed into the refrigerant, and a part of the refrigeration oil circulates through the cycle together with the refrigerant.

[0019] The compressor 11 is disposed in an engine room (not shown) and sucks, compresses and discharges the refrigerant in the refrigeration cycle device 10. The compressor 11 is an electric compressor that drives a fixed-capacity compression mechanism 11a having a fixed discharge capacity by an electric motor 11b. As the compression mechanism 11a, specifically, various compression mechanisms such as a scroll type compression mechanism and a vane type compression mechanism can be adopted.

[0020] The electric motor 11b has its operation (rotation speed) controlled by a control signal output from the control device 40, and may be an AC motor or a DC motor. The refrigerant discharge capacity of the compression mechanism 11a is changed by controlling the rotation speed of the electric motor 11b. Therefore, in this embodiment, the electric motor 11b constitutes a discharge capacity changing means for the compression mechanism 11a.

[0021] The discharge port side of the compressor 11 is connected to the inlet side of the interior condenser 12. The interior condenser 12 is disposed in a casing 31 of the interior air-conditioning unit 30, and is a radiator that radiates heat from the discharged refrigerant (i.e., high-pressure refrigerant) discharged from the compressor 11, and heats the air to be blown into the vehicle interior that has passed through the interior evaporator 20.

[0022] 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 (in other words, the throttle opening) of the first refrigerant passage 13 is arranged in the first refrigerant passage 13. The first expansion valve 14 is a first pressure reducing section of the refrigeration cycle device 10.

[0023] More specifically, the first expansion valve 14 is an electric variable throttling mechanism comprising a valve body configured to change the passage opening (in other words, the throttling opening) of the first refrigerant passage 13, and an electric actuator consisting of a stepping motor that changes the throttling opening of the valve body.

[0024] The first expansion valve 14 of the present embodiment is configured as a variable throttling mechanism with a full opening function that fully opens the first refrigerant passage 13 when the throttling opening is fully opened. In other words, the first expansion valve 14 can prevent the refrigerant from being decompressed by fully opening the first refrigerant passage 13. The operation of the first expansion valve 14 is controlled by a control signal output from the control device 40.

[0025] 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 exchanges heat between the refrigerant flowing therethrough and the outside air blown by a blower fan (not shown). The outdoor heat exchanger 15 functions as an evaporator (first evaporator) that evaporates the refrigerant and exerts a heat absorbing effect in the heating mode, etc., and functions as a radiator that radiates heat from the refrigerant in the cooling mode, etc.

[0026] Connected to the outlet side of the outdoor heat exchanger 15 are a second refrigerant passage 16 that guides the refrigerant flowing out from the outdoor heat exchanger 15 to the suction side of the compressor 11 via the accumulator 21, and a third refrigerant passage 18 that guides the refrigerant flowing out from the outdoor heat exchanger 15 to the suction side of the compressor 11 via the indoor evaporator 20 and the accumulator 21.

[0027] A first on-off valve (first on-off portion) 17 is disposed in the second refrigerant passage 16. The first on-off valve 17 is an electromagnetic valve that opens and closes the second refrigerant passage 16, and the operation thereof is controlled by a control signal output from the control device 40.

[0028] When the first on-off valve 17 is open, the pressure loss that occurs when the refrigerant passes through the second refrigerant passage 16 is smaller than the pressure loss that occurs when the refrigerant passes through the third refrigerant passage 18. This is because the check valve 24 and the second expansion valve 19 are arranged in the third refrigerant passage 18. Therefore, the refrigerant that flows out of the outdoor heat exchanger 15 flows to the second refrigerant passage 16 side when the first on-off valve 17 is open, and flows to the third refrigerant passage 18 side when the first on-off valve 17 is closed.

[0029] In this way, the first on-off valve 17 functions to switch the cycle configuration (refrigerant flow path) by opening and closing the second refrigerant passage 16. Therefore, the first on-off valve 17 constitutes a refrigerant flow path switching means that switches the refrigerant flow path of the refrigerant circulating in the cycle.

[0030] Further, a second expansion valve 19 configured to be able to change the passage area (throttle opening) of the third refrigerant passage 18 is disposed in the third refrigerant passage 18. The second expansion valve 19 is a second pressure reducing section of the refrigeration cycle apparatus 10.

[0031] More specifically, the second expansion valve 19 is an electric variable throttling mechanism comprising a valve body configured to change the passage opening (throttle opening) of the third refrigerant passage 18, and an electric actuator consisting of a stepping motor that changes the throttle opening of the valve body.

[0032] The second expansion valve 19 of the present embodiment is configured as a variable throttling mechanism with a full opening function that fully opens the third refrigerant passage 18 when the throttling opening is fully opened, and a full closing function that closes the third refrigerant passage 18 when the throttling opening is fully closed. In other words, the second expansion valve 19 can be made not to exert a decompression effect on the refrigerant, and can open and close the third refrigerant passage 18. The operation of the second expansion valve 19 is controlled by a control signal output from the control device 40.

[0033] The outlet side of the second expansion valve 19 is connected to the inlet side of the interior evaporator 20. The interior evaporator 20 is disposed inside the casing 31 of the interior air conditioning unit 30, upstream of the interior condenser 12 in the flow of air blown into the vehicle interior, and is an evaporator that evaporates the refrigerant flowing therethrough during a cooling mode, a dehumidifying heating mode, etc., by heat exchange with the air blown into the vehicle interior before passing through the interior condenser 12, thereby exerting a heat absorption effect to cool the air blown into the vehicle interior.

[0034] An inlet side of a motor-operated valve 25 is connected to an outlet side of the indoor evaporator 20. The motor-operated valve 25 is disposed on the outlet side of the indoor evaporator 20 in the third refrigerant passage 18, and is a constant pressure adjustment unit that maintains the pressure of the refrigerant on the outlet side of the indoor evaporator 20 at a predetermined value (0.3 MPa in this embodiment).

[0035] The electric valve 25 is an electric variable throttling mechanism comprising a valve body configured to change the passage opening (throttle opening) of the third refrigerant passage 18, and an electric actuator consisting of a stepping motor that changes the throttle opening of the valve body.

[0036] The motor-operated valve 25 is configured as a variable throttle mechanism with a full-closing function that fully closes the third refrigerant passage 18. The motor-operated valve 25 is an opening adjustment unit that adjusts the opening of the refrigerant passage in parallel with the exterior heat exchanger 15, downstream of the interior evaporator 20. The operation of the motor-operated valve 25 is controlled by a control signal output from the control device 40.

[0037] The outlet side of the motor-operated valve 25 is connected to the inlet side of the accumulator 21. The accumulator 21 is a gas-liquid separator that separates the refrigerant that flows into it into gas and liquid and stores the surplus refrigerant in the cycle. The gas-phase refrigerant outlet of the accumulator 21 is connected to the suction port side of the compressor 11. Therefore, the accumulator 21 serves to suppress the liquid-phase refrigerant from being sucked into the compressor 11 and to prevent liquid compression in the compressor 11.

[0038] In this embodiment, a bypass passage 22 is provided to guide the refrigerant in the first refrigerant passage 13 in a range from the outlet side of the indoor condenser 12 to the inlet side of the first expansion valve 14, to a range in the third refrigerant passage 18 from the outlet side of the outdoor heat exchanger 15 to the inlet side of the second expansion valve 19. In other words, the bypass passage 22 is a refrigerant passage that guides the refrigerant that flows out of the indoor condenser 12 to the inlet side of the second expansion valve 19, bypassing the first expansion valve 14 and the outdoor heat exchanger 15.

[0039] A second on-off valve (second on-off unit) 23 is disposed in the bypass passage 22. The second on-off valve 23 is an electromagnetic valve that opens and closes the bypass passage 22, and the operation thereof is controlled by a control signal output from the control device 40.

[0040] The second on-off valve 23 switches the cycle configuration (refrigerant flow path) by opening and closing the bypass passage 22. Therefore, the second on-off valve 23, together with the first on-off valve 17, constitutes a refrigerant flow path switching means for switching the refrigerant flow path of the refrigerant circulating in the cycle.

[0041] Furthermore, in this embodiment, a check valve (backflow prevention means) 24 is arranged in the third refrigerant passage 18 between the outlet side of the outdoor heat exchanger 15 and the junction of the bypass passage 22 and the third refrigerant passage 18. 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 and prohibits the refrigerant from the inlet side of the second expansion valve 19 to the outlet side of the outdoor heat exchanger 15. The check valve 24 can prevent the refrigerant that has merged with the third refrigerant passage 18 from the bypass passage 22 from flowing toward the outdoor heat exchanger 15.

[0042] Next, a description will be given of the interior air conditioning unit 30. The interior air conditioning unit 30 is disposed inside the instrument panel at the frontmost part of the vehicle interior, and houses a blower 32, the interior condenser 12, the interior evaporator 20, a heater core 34, etc. in a casing 31 that forms the outer shell of the unit.

[0043] The casing 31 forms an air passage for blowing air 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 that switches between introducing inside the vehicle cabin air (inside air) and outside air is disposed on the most upstream side of the blown air flow in the casing 31.

[0044] 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. Furthermore, an inside / outside air switching door is arranged inside the inside / outside air switching device 33, which continuously 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.

[0045] A blower 32 is disposed on the air flow downstream side of the inside / outside air switching device 33, which blows the air introduced through the inside / outside air switching device 33 toward the vehicle cabin. The blower 32 is an electric blower in which a centrifugal multi-blade fan (sirocco fan) 32a is driven by an electric motor 32b, and the rotation speed (airflow rate) is controlled by a control signal (control voltage) output from the control device 40. The centrifugal multi-blade fan 32a functions as a blowing means for blowing air into the vehicle cabin.

[0046] The interior evaporator 20, the heater core 34, and the interior condenser 12 are arranged in this order with respect to the flow of air to be blown into the vehicle compartment on the air flow downstream side of the blower 32. In other words, the interior evaporator 20 is arranged on the upstream side of the interior condenser 12 and the heater core 34 with respect to the flow direction of the air to be blown into the vehicle compartment.

[0047] Here, the heater core 34 is a heating heat exchanger that exchanges heat between the cooling water of the engine that outputs the driving force for running the vehicle and the air blown into the vehicle compartment. The heater core 34 in this embodiment is disposed upstream of the interior condenser 12 in the flow direction of the air blown into the vehicle compartment. In addition, a cold 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.

[0048] 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, for adjusting the ratio of the air volume passing through the indoor condenser 12 and the heater core 34 to the air passing through the cold air bypass passage 35, among the air after passing through the indoor evaporator 20. In addition, a mixing space is provided downstream of the indoor condenser 12 in the air flow and downstream of the cold air bypass passage 35 in the air flow, for mixing the air that has passed through the indoor condenser 12 and the cold air bypass passage 35.

[0049] Furthermore, an air outlet (not shown) for blowing the conditioned air mixed in the mixing space into the vehicle interior, which is the space to be air-conditioned, is disposed on the most downstream side of the blown air flow of the casing 31. Specifically, the air outlets include a face air outlet for blowing the conditioned air to the upper bodies of the occupants in the vehicle interior, a foot air outlet for blowing the conditioned air to the feet of the occupants, and a defroster air outlet for blowing the conditioned air to the inside surface of the vehicle front windshield.

[0050] Therefore, the air mix door 36 adjusts the ratio of the air volumes of the air passing through the indoor condenser 12 and the air passing through the cold air bypass passage 35, thereby adjusting the temperature of the conditioned air mixed in the mixing space and adjusting the temperature of the conditioned air blown out from each air outlet. The air mix door 36 is driven by a servo motor (not shown) which operates according to a control signal output from the control device 40.

[0051] Furthermore, upstream of the blown air flow of the face outlet, foot outlet, and defroster outlet, there are provided a face door (not shown) that adjusts the opening area of ​​the face outlet, a foot door (not shown) that adjusts the opening area of ​​the foot outlet, and a defroster door (not shown) that adjusts the opening area of ​​the defroster outlet.

[0052] These face doors, foot doors, and defroster doors constitute an air outlet mode switching means for switching the air outlet mode, and are driven by a servo motor (not shown) whose operation is controlled by a control signal output from the control device 40 via a link mechanism or the like.

[0053] Next, the electric control unit of this embodiment will be described. The control device 40 is composed of a well-known microcomputer including a CPU, ROM, RAM, etc., and its peripheral circuits, and performs various calculations and processing based on the control programs stored in the ROM, and controls the operation of various control devices connected to the output side.

[0054] In addition, connected to the input side of the control device 40 are various sensors for air conditioning control, such as an inside air sensor that detects the interior temperature Tr, an outside air sensor that detects the outside air temperature Tam, a solar radiation sensor that detects the amount of solar radiation Ts inside the vehicle cabin, an evaporator temperature sensor serving as an evaporator discharge temperature detection means that detects the temperature of the air blown out from the interior evaporator 20 (evaporator temperature) Te, a discharge temperature sensor Td that detects the temperature of the refrigerant discharged from the compressor 11, and a blown air temperature sensor serving as a blown temperature detection means that detects the temperature of the air blown into the vehicle cabin (vehicle interior blown air temperature) TAV.

[0055] Furthermore, an operation panel (not shown) disposed near the instrument panel at the front of the vehicle interior is connected to the input side of the control device 40, and operation signals are input from various operation switches provided on the operation panel. Specifically, the various operation switches provided on the operation panel include an air conditioner switch (A / C switch) for setting whether or not the air to be blown into the vehicle interior is cooled by the interior air conditioning unit 30, a temperature setting switch for setting the set temperature inside the vehicle interior, and the like.

[0056] The control device 40 is an integrated configuration of control means for controlling the operation of various control devices connected to its output side, and the configurations (software and hardware) for controlling the operation of each control device constitute the control means for controlling the operation of each control device.

[0057] For example, the configuration for controlling the electric motor of the compressor 11 constitutes a discharge capacity control means, the configuration for controlling the first expansion valve 14 constitutes a first throttling control means, the configuration for controlling the second expansion valve 19 constitutes a second throttling control means, and the configuration for controlling the first and second on-off valves 17, 23 constitutes a flow path switching control means.

[0058] Next, a description will be given of the operation of the vehicle air conditioner 1 of this embodiment in the above configuration. As described above, the vehicle air conditioner 1 of this embodiment can be switched among a cooling mode for cooling the vehicle interior, a heating mode for heating the vehicle interior, and a dehumidification heating mode for heating the vehicle interior while dehumidifying it.

[0059] The switching control process for each operation mode will be described with reference to Fig. 2. Fig. 2 is a flowchart showing the flow of the control process executed by the control device 40 of the vehicle air conditioner 1 of this embodiment. The flowchart in Fig. 2 is executed as a subroutine of a main routine for air conditioning control (not shown). Each control step in Fig. 2 constitutes various function realization means possessed by the control device 40.

[0060] First, the control device 40 reads the detection signals of the above-mentioned sensors and the operation signal of the operation panel (S10), and calculates a target blown-out temperature TAO, which is a target temperature of the air blown into the vehicle cabin, based on the values ​​of the read detection signals and operation signals, using the following formula F1 (S20). Therefore, the control step S20 in this embodiment constitutes a target blown-out temperature determination means. TAO=Kset×Tset-Kr×Tr-Kam×Tam-Ks×Ts+C…(F1) In addition, Tset is the vehicle interior temperature set by the temperature setting switch, Tr is the vehicle interior temperature (inside air temperature) detected by the inside air sensor, Tam is the outside air temperature detected by the outside air sensor, and Ts is the amount of solar radiation detected by the solar radiation sensor. Kset, Kr, Kam, and Ks are control gains, and C is a correction constant.

[0061] Next, it is determined whether the A / C switch on the operation panel is turned on (S30). If it is determined that the A / C switch is turned off (S30: NO), the operation mode is determined to be a heating mode in which the air blown into the vehicle cabin is not cooled by the interior air conditioning unit 30 (S40). If it is determined that the A / C switch is turned on (S30: YES), the process proceeds to step S50.

[0062] In step S50, it is determined whether the target air outlet temperature TAO is lower than a predetermined cooling reference temperature α. If it is determined that the target air outlet temperature TAO is lower than the cooling reference temperature α (S50: YES), the operation mode is set to the cooling mode to cool the passenger compartment (S60). If it is determined that the target air outlet temperature TAO is equal to or higher than the cooling reference temperature α (S50: YES), the process proceeds to step S70.

[0063] In step S70, it is determined whether the detection value of the outside air sensor (outside air temperature) is higher than a predetermined outside air reference temperature T1. As a result, if it is determined that the detection value of the outside air sensor is higher than the outside air reference temperature T1 (S70: YES), it is further determined whether the temperature difference (=TAV-TAO) between the detection value of the blown air temperature sensor (cabin blown air temperature TAV) and the target blown air temperature TAO is smaller than a predetermined reference value β (hereinafter referred to as threshold value β) (S80).

[0064] If it is determined in step S80 that the temperature difference between the air temperature T blown into the vehicle cabin and the target air temperature TAO is smaller than the threshold value β (S80: YES), the first dehumidification and heating mode is selected, which is a normal dehumidification and heating mode in which the temperature of the air blown into the vehicle cabin can be adjusted over a wide range from low to high temperatures (S90).

[0065] On the other hand, if it is determined that the detection value of the outside air sensor is equal to or lower than the outside air reference temperature T1 (S70: NO), or if it is determined that the temperature difference between the air blown into the vehicle cabin TAV and the target blown air temperature TAO is equal to or higher than the threshold value β (S80: NO), the second dehumidification and heating mode is selected, in which the temperature adjustable range of the air blown into the vehicle cabin is higher than that of the first dehumidification and heating mode (S100).

[0066] In this manner, the operation modes can be appropriately switched among the heating mode, the cooling mode, the first dehumidification heating mode, and the second dehumidification heating mode depending on the operating environment of the vehicle air conditioner 1.

[0067] Next, operations in the heating mode, the cooling mode, the first dehumidifying and heating mode, and the second dehumidifying and heating mode will be described.

[0068] (A) Heating mode In the heating mode, the control device 40 opens the second refrigerant passage 16 with the first on-off valve 17 and closes (blocks) the bypass passage 22 with the second on-off valve 23. Furthermore, the third refrigerant passage 18 is closed (fully closed) with the second expansion valve 19. As a result, in the refrigeration cycle device 10, the refrigerant flow path is switched to one in which the refrigerant flows as shown by the black arrows in FIG.

[0069] With this refrigerant flow path configuration, the control device 40 determines the operating states of various control devices connected to the control device 40 (control signals to be output to various control devices) based on the target blowing temperature TAO, detection signals from the sensor group, etc.

[0070] For example, the refrigerant discharge capacity of the compressor 11, i.e., the control signal output to the electric motor 11b of the compressor 11, is determined as follows: First, a target condenser temperature TCO of the indoor condenser 12 is determined based on the target blowing temperature TAO with reference to a control map previously stored in the control device 40.

[0071] Then, based on the deviation between the target condenser temperature TCO and the detection value of the discharge temperature sensor, a feedback control method is used to determine a control signal to be output to the electric motor 11b of the compressor 11 so that the temperature of the air blown into the vehicle cabin approaches the target discharge temperature TAO.

[0072] Moreover, the control signal output to the first expansion valve 14 is determined 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 coefficient of performance (COP) of the cycle. The control signal output to the motor-operated valve 25 is determined so that the opening degree becomes a predetermined fixed opening degree.

[0073] In addition, the control signal output to the servo motor of the air mix door 36 is determined so that the air mix door 36 blocks the cold air bypass passage 35 and the total flow rate of the blown air after passing through the indoor evaporator 20 passes through the air passage of the heater core 34 and the indoor condenser 12.

[0074] Then, the control signals and the like determined as described above are output to the various control devices. Thereafter, a control routine including a process of determining an operation mode, determining the operation states of the various control devices, and outputting control signals and the like is repeated at predetermined intervals until a request to stop the operation of the vehicle air conditioner 1 is made through the operation panel. Note that such repetition of the control routine is also performed in the other operation modes.

[0075] Therefore, in the refrigeration cycle device 10 in the heating mode, the high-pressure refrigerant discharged from the compressor 11 flows into the interior condenser 12. The refrigerant that flows into the interior condenser 12 exchanges heat with the air blown into the vehicle compartment by the blower 32 and passing through the interior evaporator 20, and dissipates heat. As a result, the air blown into the vehicle compartment is heated.

[0076] The refrigerant flowing out from the indoor condenser 12 flows into the first expansion valve 14 via the first refrigerant passage 13, and is reduced in pressure and expanded in the first expansion valve 14 until it becomes a low-pressure refrigerant. The low-pressure refrigerant reduced in pressure in the first expansion valve 14 then flows into the outdoor heat exchanger 15 and absorbs heat from the outside air blown by the blower fan. The refrigerant flowing out from the outdoor heat exchanger 15 flows into the accumulator 21 via the second refrigerant passage 16, and is separated into gas and liquid.

[0077] Then, the gas phase refrigerant separated in the accumulator 21 is sucked into the suction side of the compressor 11 and compressed again by the compressor 11. The liquid phase refrigerant separated in the accumulator 21 is stored inside the accumulator 21 as surplus refrigerant that is not required for the cycle to exhibit the required refrigeration capacity. Since the third refrigerant passage 18 is closed by the second expansion valve 19, no refrigerant flows into the indoor evaporator 20.

[0078] 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 blown into the vehicle cabin, and the heater core 34 dissipates heat from the coolant to the air blown into the vehicle cabin, so that the heated air blown into the vehicle cabin can be blown into the vehicle cabin. This realizes heating of the vehicle cabin.

[0079] (B) Cooling mode In the cooling mode, the control device 40 closes the second refrigerant passage 16 with the first on-off valve 17, and closes the bypass passage 22 with the second on-off valve 23. Furthermore, the first expansion valve 14 fully opens the first refrigerant passage 13, and the motor-operated valve 25 fully opens. As a result, the refrigeration cycle device 10 is switched to the first refrigerant passage through which the refrigerant flows as shown by the outlined arrow in FIG.

[0080] With this refrigerant flow path configuration, the control device 40 determines the operating states of various control devices connected to the control device 40 (control signals to be output to various control devices) based on the target blowing temperature TAO, detection signals from the sensor group, etc.

[0081] For example, the refrigerant discharge capacity of the compressor 11, i.e., the control signal output to the electric motor 11b of the compressor 11, is determined as follows. First, a target evaporator outlet temperature TEO of the blown air from the indoor evaporator 20 is determined based on the target outlet temperature TAO, with reference to a control map stored in advance in the control device 40. Therefore, among the control routines executed by the control device 40, the control step of determining the target evaporator outlet temperature TEO constitutes a target evaporator outlet temperature determination means.

[0082] Then, based on the deviation between the target evaporator discharge temperature TEO and the detection value of the evaporator temperature sensor, a control signal is determined using a feedback control technique to be output to the electric motor 11b of the compressor 11 so that the temperature of the air passing through the indoor evaporator 20 approaches the target discharge temperature TAO.

[0083] In addition, the control signal output to the second expansion valve 19 is determined 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 bring the COP closer to the maximum value.

[0084] In addition, the control signal output to the servo motor of the air mix door 36 is determined so that the air mix door 36 blocks the air passage of the heater core 34 and the indoor condenser 12, and the total flow rate of the blown air after passing through the indoor evaporator 20 passes through the cold air bypass passage 35.

[0085] Therefore, in the cooling mode of the refrigeration cycle device 10, the high-pressure refrigerant discharged from the compressor 11 flows into the interior condenser 12. At this time, since the air mix door 36 closes the air passages of the heater core 34 and the interior condenser 12, 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 blown into the vehicle cabin.

[0086] The refrigerant flowing out from the indoor condenser 12 flows into the first expansion valve 14 via the first refrigerant passage 13. At this time, since the first expansion valve 14 fully opens the first refrigerant passage 13, the refrigerant flowing out from the indoor condenser 12 flows into the outdoor heat exchanger 15 without being depressurized by the first expansion valve 14. Then, the refrigerant that has flowed into the outdoor heat exchanger 15 dissipates heat in the outdoor heat exchanger 15 to the outside air blown by the blower fan.

[0087] The refrigerant flowing out from the exterior heat exchanger 15 flows into the second expansion valve 19 via the third refrigerant passage 18, where it is reduced in pressure and expanded to become a low-pressure refrigerant. The low-pressure refrigerant reduced in pressure by the second expansion valve 19 flows into the interior evaporator 20, where it absorbs heat from the air blown into the vehicle compartment by the blower 32 and evaporates. This cools the air blown into the vehicle compartment.

[0088] The refrigerant flowing out from the indoor evaporator 20 flows into the accumulator 21 and is separated into gas and liquid. Then, the gas-phase refrigerant separated in the accumulator 21 is sucked into the suction side of the compressor 11 and compressed again by the compressor 11. The liquid-phase refrigerant separated in the accumulator 21 is stored inside the accumulator 21 as surplus refrigerant that is not required for the cycle to exhibit the required refrigeration capacity.

[0089] As described above, in the cooling mode, the air passages of the interior condenser 12 and the heater core 34 are closed by the air mix door 36, so that the air cooled by the interior evaporator 20 can be blown out into the vehicle interior. This allows the interior of the vehicle to be cooled.

[0090] (C) 1st dehumidification heating mode In the first dehumidifying and heating mode, the control device 40 closes the second refrigerant passage 16 with the first on-off valve 17 and closes the bypass passage 22 with the second on-off valve 23. Then, the first expansion valve 14 and the second expansion valve 19 are throttled or fully open, and the motor-operated valve 25 is fully open. As a result, the refrigeration cycle device 10 is switched to the first refrigerant passage in which the refrigerant flows as shown by the outlined horizontal arrow in Fig. 1, similar to the cooling mode. In the first dehumidifying and heating mode (first refrigerant passage), the outdoor heat exchanger 15 and the indoor evaporator 20 are connected in series with respect to the refrigerant flow.

[0091] With this refrigerant flow path configuration, the control device 40 determines the operating states of various control devices connected to the control device 40 (control signals to be output to various control devices) based on the target blowing temperature TAO, detection signals from the sensor group, etc.

[0092] For example, the control signal output to the electric motor 11b of the compressor 11 is determined in the same manner as in the cooling mode. Also, the control signal output to the servo motor of the air mix door 36 is determined so that the air mix door 36 closes the cool air bypass passage 35 and the total flow rate of the blown air after passing through the indoor evaporator 20 passes through the air passage of the heater core 34 and the indoor condenser 12.

[0093] The first expansion valve 14 and the second expansion valve 19 are changed according to a target blowing temperature TAO, which is a target temperature of the air blown into the vehicle cabin. Specifically, as the target blowing temperature TAO, which is the target temperature of the air blown into the vehicle cabin, increases, the control device 40 causes the first expansion valve 14 to reduce the passage area of ​​the first refrigerant passage 13 and the second expansion valve 19 to increase the passage area of ​​the third refrigerant passage 18. As a result, in the first dehumidification heating mode, four modes, from the first mode to the fourth mode, are executed.

[0094] (C-1) First mode The first mode is executed when, in the first dehumidification and heating mode, the target air outlet temperature TAO is equal to or higher than the cooling reference temperature α and equal to or lower than a predetermined first reference temperature.

[0095] In the first mode, the first expansion valve 14 fully opens the first refrigerant passage 13, and the second expansion valve 19 is throttled. Therefore, although the cycle configuration (refrigerant passage) is exactly the same as that in the cooling mode, the air mix door 36 fully opens the air passages on the indoor condenser 12 and heater core 34 sides, so the state of the refrigerant circulating in the cycle changes as shown in the Mollier diagram of FIG.

[0096] That is, as shown in Fig. 3, the high-pressure refrigerant (point a1) discharged from the compressor 11 flows into the interior condenser 12 and dissipates heat through heat exchange with the air to be blown into the vehicle compartment that has been cooled and dehumidified by the interior evaporator 20 (points a1 and a2 in Fig. 3). As a result, the air to be blown into the vehicle compartment is heated.

[0097] The refrigerant flowing out from the indoor condenser 12 flows into the first expansion valve 14 via the first refrigerant passage 13. At this time, since the first expansion valve 14 fully opens the first refrigerant passage 13, the refrigerant flowing out from the indoor condenser 12 flows into the outdoor heat exchanger 15 without being depressurized by the first expansion valve 14. Then, the refrigerant that has flowed into the outdoor heat exchanger 15 dissipates heat to the outside air blown by the blower fan in the outdoor heat exchanger 15 (points a2 and a3 in FIG. 3).

[0098] The refrigerant flowing out from the exterior heat exchanger 15 flows into the second expansion valve 19 via the third refrigerant passage 18, and is decompressed and expanded by the second expansion valve 19 until it becomes a low-pressure refrigerant (points a3 and a4 in FIG. 3). The low-pressure refrigerant decompressed by the second expansion valve 19 flows into the interior evaporator 20, and evaporates by absorbing heat from the air blown into the vehicle compartment by the blower 32 (points a4 and a5 in FIG. 3). This cools the air blown into the vehicle compartment. The refrigerant flowing out from the interior evaporator 20 flows to the accumulator 21 and the suction side of the compressor 11, and is compressed again by the compressor 11, as in the cooling mode.

[0099] As described above, in the first mode of the first dehumidifying and heating mode, the air to be blown into the vehicle cabin that has been cooled and dehumidified by the interior evaporator 20 can be heated by the interior condenser 12 and blown into the vehicle cabin. This allows the dehumidifying and heating of the vehicle cabin to be achieved.

[0100] (C-2) Second mode The second mode is executed when the target blowing temperature TAO is higher than the first reference temperature and is equal to or lower than a predetermined second reference temperature. In the second mode, the first expansion valve 14 is in a throttled state, and the throttle opening of the second expansion valve 19 (the passage area of ​​the third refrigerant passage 18) is increased from that in the first mode. Therefore, in the second mode, the state of the refrigerant circulating in the cycle changes as shown in the Mollier diagram of FIG.

[0101] That is, as shown in Fig. 4, the high-pressure refrigerant (point b1) discharged from the compressor 11 flows into the interior condenser 12 and dissipates heat through heat exchange with the air to be blown into the vehicle compartment that has been cooled and dehumidified by the interior evaporator 20 (points b1 and b2 in Fig. 4). As a result, the air to be blown into the vehicle compartment is heated.

[0102] The refrigerant flowing out from the indoor condenser 12 flows into the first expansion valve 14 via the first refrigerant passage 13, and is reduced in pressure to become an intermediate-pressure refrigerant (points b2 and b3 in FIG. 4). Then, the intermediate-pressure refrigerant reduced in pressure by the first expansion valve 14 flows into the outdoor heat exchanger 15, and dissipates heat to the outside air blown by the blower fan (points b3 and b4 in FIG. 4).

[0103] The refrigerant flowing out from the exterior heat exchanger 15 flows into the second expansion valve 19 via the third refrigerant passage 18, and is decompressed and expanded by the second expansion valve 19 until it becomes a low-pressure refrigerant (points b4 and b5 in FIG. 4). The low-pressure refrigerant decompressed by the second expansion valve 19 flows into the interior evaporator 20, and evaporates by absorbing heat from the air blown into the vehicle compartment by the blower 32 (points b5 and b6 in FIG. 4). This cools the air blown into the vehicle compartment. The refrigerant flowing out from the interior evaporator 20 flows to the accumulator 21 and the suction side of the compressor 11, and is compressed again by the compressor 11, in the same manner as in the cooling mode.

[0104] As described above, in the second mode of the first dehumidifying and heating mode, the air to be blown into the vehicle cabin that has been cooled and dehumidified by the interior evaporator 20 can be heated by the interior condenser 12 and blown into the vehicle cabin, similar to the first mode. This allows the dehumidifying and heating of the vehicle cabin to be achieved.

[0105] At this time, in the second mode, since the first expansion valve 14 is in a throttled state, it is possible to lower the temperature of the refrigerant flowing into the outdoor heat exchanger 15 compared to the first mode. Therefore, it is possible to reduce the temperature difference between the refrigerant temperature in the outdoor heat exchanger 15 and the outside air temperature, and to reduce the amount of heat dissipated by the refrigerant in the outdoor heat exchanger 15.

[0106] As a result, the amount of heat dissipated by the refrigerant in the indoor condenser 12 can be increased without increasing the refrigerant circulation flow rate circulating through the cycle compared to the first mode, and the temperature of the air blown out from the indoor condenser 12 can be increased more than in the first mode.

[0107] (C-3) Third mode The third mode is executed when the target blowing temperature TAO is higher than the second reference temperature and is equal to or lower than a predetermined third reference temperature. In the third mode, the throttle opening of the first expansion valve 14 (the passage area of ​​the first refrigerant passage 13) is reduced from that in the second mode, and the throttle opening of the second expansion valve 19 (the passage area of ​​the third refrigerant passage 18) is increased from that in the second mode. Therefore, in the third mode, the state of the refrigerant circulating in the cycle changes as shown in the Mollier diagram of FIG. 5.

[0108] That is, as shown in Fig. 5, the high-pressure refrigerant (point c1) discharged from the compressor 11 flows into the interior condenser 12 and dissipates heat through heat exchange with the air to be blown into the vehicle compartment that has been cooled and dehumidified by the interior evaporator 20 (points c1 and c2 in Fig. 5). As a result, the air to be blown into the vehicle compartment is heated.

[0109] The refrigerant flowing out from the indoor condenser 12 flows into the first expansion valve 14 via the first refrigerant passage 13, and is reduced in pressure until it becomes an intermediate-pressure refrigerant whose temperature is lower than the outside air temperature (points c2 and c3 in FIG. 5). Then, the intermediate-pressure refrigerant reduced in pressure by the first expansion valve 14 flows into the outdoor heat exchanger 15, and absorbs heat from the outside air blown by the blower fan (points c3 and c4 in FIG. 5).

[0110] The refrigerant flowing out from the exterior heat exchanger 15 flows into the second expansion valve 19 via the third refrigerant passage 18, and is decompressed and expanded by the second expansion valve 19 until it becomes a low-pressure refrigerant (points c4 and c5 in FIG. 5). The low-pressure refrigerant decompressed by the second expansion valve 19 flows into the interior evaporator 20, and evaporates by absorbing heat from the air blown into the vehicle compartment by the blower 32 (points c5 and c6 in FIG. 5). This cools the air blown into the vehicle compartment. The refrigerant flowing out from the interior evaporator 20 flows to the accumulator 21 and the suction side of the compressor 11, and is compressed again by the compressor 11, in the same manner as in the cooling mode.

[0111] As described above, in the third mode of the first dehumidifying and heating mode, similarly to the first and second modes, the air to be blown into the vehicle cabin that has been cooled and dehumidified by the interior evaporator 20 can be heated by the interior condenser 12 and blown into the vehicle cabin. This allows dehumidifying and heating the vehicle cabin.

[0112] At this time, in the third mode, the throttle opening of the first expansion valve 14 is reduced to cause the outdoor heat exchanger 15 to function as a heat absorber (evaporator), so that the temperature blown out from the indoor condenser 12 can be increased more than in the second mode.

[0113] As a result, the density of the refrigerant suctioned into the compressor 11 can be increased compared to the second mode, and the amount of heat dissipated by the refrigerant in the indoor condenser 12 can be increased without increasing the rotation speed (refrigerant discharge capacity) of the compressor 11, and the temperature of the air blown out from the indoor condenser 12 can be increased more than in the second mode.

[0114] (C-4) Fourth mode The fourth mode is executed when the target blowing temperature TAO becomes higher than the third reference temperature. In the fourth mode, the throttle opening of the first expansion valve 14 (the passage area of ​​the first refrigerant passage 13) is reduced from that in the third mode, and the third refrigerant passage 18 is fully opened by the second expansion valve 19. Therefore, in the fourth mode, the state of the refrigerant circulating in the cycle changes as shown in the Mollier diagram of FIG.

[0115] That is, as shown in Fig. 6, the high-pressure refrigerant (point d1) discharged from the compressor 11 flows into the interior condenser 12 and dissipates heat through heat exchange with the air to be blown into the vehicle compartment that has been cooled and dehumidified by the interior evaporator 20 (points d1 and d2 in Fig. 6). As a result, the air to be blown into the vehicle compartment is heated.

[0116] The refrigerant flowing out from the indoor condenser 12 flows into the first expansion valve 14 via the first refrigerant passage 13 and is reduced in pressure to become a low-pressure refrigerant (points d2 and d3 in FIG. 6). The low-pressure refrigerant reduced in pressure by the first expansion valve 14 then flows into the outdoor heat exchanger 15 and absorbs heat from the outside air blown by the blower fan (points d3 and d4 in FIG. 6).

[0117] The refrigerant flowing out from the outdoor heat exchanger 15 flows into the second expansion valve 19 via the third refrigerant passage 18. At this time, since the second expansion valve 19 fully opens the third refrigerant passage 18, the refrigerant flowing out from the outdoor heat exchanger 15 flows into the indoor evaporator 20 without being decompressed by the second expansion valve 19.

[0118] The low-pressure refrigerant that has flowed into the interior evaporator 20 absorbs heat from the air blown into the vehicle compartment by the blower 32 and evaporates (points d4 and d5 in FIG. 6). This cools the air blown into the vehicle compartment. The refrigerant that has flowed out of the interior evaporator 20 flows to the accumulator 21 and the suction side of the compressor 11, and is compressed again by the compressor 11, in the same manner as in the cooling mode.

[0119] As described above, in the fourth mode of the first dehumidifying and heating mode, similarly to the first to third modes, the air to be blown into the vehicle cabin that has been cooled and dehumidified by the interior evaporator 20 can be heated by the interior condenser 12 and blown out into the vehicle cabin. This allows dehumidifying and heating the vehicle cabin.

[0120] At this time, in the fourth mode, similarly to the third mode, the outdoor heat exchanger 15 can function as a heat absorber (evaporator), and since the throttle opening of the first expansion valve 14 is reduced more than in the third mode, it is possible to lower the refrigerant evaporation temperature in the outdoor heat exchanger 15. Therefore, it is possible to increase the temperature difference between the refrigerant temperature in the outdoor heat exchanger 15 and the outside air temperature more than in the third mode, and to increase the amount of heat absorption by the refrigerant in the outdoor heat exchanger 15.

[0121] As a result, the suction refrigerant density of compressor 11 can be increased compared to the third mode, and the amount of heat dissipated by the refrigerant in indoor condenser 12 can be increased without increasing the rotation speed (refrigerant discharge capacity) of compressor 11, and the temperature of the blown air from indoor condenser 12 can be increased more than in the third mode.

[0122] In this way, in the first dehumidification heating mode, the temperature of the air blown into the vehicle cabin can be adjusted over a wide range from low temperature to high temperature (for example, a range including the intermediate temperature region shown in Figure 25) by changing the throttle opening of the first expansion valve 14 and the second expansion valve 19 according to the target blowing temperature TAO.

[0123] In other words, in the first dehumidification heating mode, the amount of heat released or absorbed by the refrigerant in the outdoor heat exchanger 15 can be adjusted by switching the outdoor heat exchanger 15 from a state in which it functions as a radiator that causes the refrigerant to release heat to a state in which it functions as an evaporator that causes the refrigerant to absorb heat.

[0124] Therefore, the amount of heat dissipated by the refrigerant in the indoor condenser 12 can be adjusted over a wider range than in a cycle configuration in which the outdoor heat exchanger 15 functions as either a radiator or an evaporator, and the temperature adjustment range of the air blown into the space to be air-conditioned during dehumidification operation can be expanded.

[0125] (D) Second dehumidification heating mode In the second dehumidifying and heating mode, the control device 40 opens the second refrigerant passage 16 with the first on-off valve 17 and opens the bypass passage 22 with the second on-off valve 23. Then, the first expansion valve 14 and the second expansion valve 19 are each throttled, and the motor-operated valve 25 is throttled. Therefore, the refrigeration cycle device 10 is switched to the second refrigerant passage in which the refrigerant flows as shown by the outlined diagonal line arrow in Fig. 1. In the second dehumidifying and heating mode (second refrigerant passage), the outdoor heat exchanger 15 and the indoor evaporator 20 are connected in parallel with respect to the refrigerant flow.

[0126] With this refrigerant flow path configuration, the control device 40 determines the operating states of various control devices connected to the control device 40 (control signals to be output to various control devices) based on the target blowing temperature TAO, detection signals from the sensor group, etc.

[0127] For example, the control signal output to the electric motor 11b of the compressor 11 is determined in the same manner as in the cooling mode. Also, the control signal output to the servo motor of the air mix door 36 is determined so that the air mix door 36 closes the cool air bypass passage 35 and the total flow rate of the blown air after passing through the indoor evaporator 20 passes through the air passage of the heater core 34 and the indoor condenser 12.

[0128] In addition, the control signal output to the first expansion valve 14 is determined 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 bring the COP closer to the maximum value.

[0129] The control signal output to the second expansion valve 19 is determined so that the degree of superheat of the refrigerant at the outlet side of the indoor evaporator 20 approaches a predetermined target degree of superheat and the opening degree of the second expansion valve 19 exceeds a first predetermined opening degree. In this example, the first predetermined opening degree is an opening degree that closes the second expansion valve 19.

[0130] The control signal output to the motor-operated valve 25 is determined so that the evaporation pressure of the indoor evaporator 20 approaches the target value and the opening degree of the motor-operated valve 25 exceeds the second predetermined opening degree. In this example, the second predetermined opening degree is an opening degree that closes the motor-operated valve 25. In other words, the control signal output to the motor-operated valve 25 is feedback-controlled based on the deviation between the target evaporation pressure of the indoor evaporator 20 and the actual evaporation pressure.

[0131] Therefore, in the refrigeration cycle device 10 in the second dehumidification heating mode, as shown in the Mollier diagram of Fig. 7, the high-pressure refrigerant (point e1) discharged from the compressor 11 flows into the interior condenser 12 and dissipates heat through heat exchange with the air to be blown into the vehicle compartment that has been cooled and dehumidified by the interior evaporator 20 (points e1 and e2 in Fig. 7). As a result, the air to be blown into the vehicle compartment is heated.

[0132] The refrigerant flowing out from the indoor condenser 12 flows into the first expansion valve 14 via the first refrigerant passage 13, and also flows into the second expansion valve 19 via the bypass passage 22. The high-pressure refrigerant flowing into the first expansion valve 14 is reduced in pressure to become low-pressure refrigerant (points e2 and e3 in FIG. 7). The low-pressure refrigerant reduced in pressure by the first expansion valve 14 then flows into the outdoor heat exchanger 15 and absorbs heat from the outside air blown by the blower fan (points e3 and e5 in FIG. 7).

[0133] Meanwhile, the high-pressure refrigerant that has flowed into the second expansion valve 19 is reduced in pressure to become a low-pressure refrigerant (points e2 and e4 in FIG. 7). The low-pressure refrigerant reduced in pressure by the second expansion valve 19 then flows into the interior evaporator 20, where it absorbs heat from the air blown into the vehicle compartment by the blower 32 and evaporates (points e4 and e6 in FIG. 7). This cools the air blown into the vehicle compartment. The pressure of the refrigerant in the interior evaporator 20 is adjusted to a constant pressure by the motor-operated valve 25.

[0134] The refrigerant flowing out from the outdoor heat exchanger 15 and the refrigerant flowing out from the indoor evaporator 20 flow to the accumulator 21 and the suction side of the compressor 11, and is compressed again by the compressor 11. In this embodiment, the pressure of the low-pressure refrigerant flowing out from the outdoor heat exchanger 15 and the pressure of the low-pressure refrigerant flowing out from the indoor evaporator 20 are equal to each other. In addition, a check valve 24 is provided in the third refrigerant passage 18, so that the refrigerant does not flow back from the bypass passage 22 to the outlet side of the outdoor heat exchanger 15.

[0135] As described above, in the second dehumidification heating mode, unlike the first dehumidification heating mode, the refrigerant flow path is such that the exterior heat exchanger 15 and the interior evaporator 20 are connected in parallel with respect to the refrigerant flow, so that the refrigerant flow rate to the interior evaporator 20 can be reduced. Therefore, the amount of heat absorbed by the refrigerant in the interior evaporator 20 can be reduced, and the temperature of the blown air dehumidified by the interior evaporator 20 can be adjusted in a higher temperature range by the interior condenser 12 than in the first dehumidification heating mode. Note that when the refrigerant flow rate to the interior evaporator 20 is reduced, it is desirable to reduce it within a range that allows sufficient dehumidification of the air blown into the vehicle cabin.

[0136] Since the electric valve 25 is arranged on the outlet side of the indoor evaporator 20, even when the refrigerant flow path connects the outdoor heat exchanger 15 and the indoor evaporator 20 in parallel, as in the second dehumidification heating mode, the refrigerant evaporation pressure in the outdoor heat exchanger 15 can be reduced below the refrigerant evaporation pressure in the indoor evaporator 20, as shown in Figure 7.

[0137] Therefore, the refrigerant evaporation pressure in the interior evaporator 20 is maintained at or above a predetermined value to prevent frost from forming on the interior evaporator 20, while the amount of heat absorbed by the refrigerant in the exterior heat exchanger 15 is increased to increase the amount of heat released by the refrigerant in the interior condenser 12. As a result, the temperature adjustment range can be expanded to increase the temperature of the air blown into the vehicle cabin in the second dehumidifying and heating mode.

[0138] In the vehicle air conditioning system 1 of the present embodiment described above, as described above, by switching the refrigerant flow path of the refrigeration cycle device 10, appropriate cooling, heating, and dehumidifying and heating can be performed in the vehicle cabin, thereby achieving comfortable air conditioning in the vehicle cabin.

[0139] In particular, in the vehicle air conditioning system 1 of this embodiment, the dehumidifying and heating modes can be switched between a first dehumidifying and heating mode in which the heat exchange capacity (heat dissipation capacity and heat absorption capacity) in the exterior heat exchanger 15 is adjusted to adjust the temperature of the air blown into the passenger compartment over a wide range from low to high temperatures, and a second dehumidifying and heating mode in which the temperature of the air blown into the passenger compartment can be adjusted to a higher temperature range than in the first dehumidifying and heating mode.

[0140] Therefore, the range in which the temperature of the air blown into the vehicle interior, which is the space to be air-conditioned, can be adjusted can be expanded.

[0141] Furthermore, since the first dehumidification heating mode and the second dehumidification heating mode can be switched using a simple configuration such as the first on-off valve 17 and the second on-off valve 23, a configuration can be specifically and easily realized that expands the temperature adjustment range of the air blown into the vehicle cabin.

[0142] As described above, in the second dehumidifying and heating mode, the motor-operated valve 25 maintains the refrigerant evaporation pressure in the indoor evaporator 20 at or above a predetermined value to prevent frost from forming on the indoor evaporator 20. However, during transient load fluctuations, the refrigerant evaporation pressure in the indoor evaporator 20 may fall below the predetermined value and drop to the frost region.

[0143] Therefore, in this embodiment, when the refrigerant temperature Te in the indoor evaporator 20 becomes equal to or lower than a predetermined value Te1 (e.g., 0°C), the control device 40 performs frost suppression control to suppress the formation of frost on the indoor evaporator 20.

[0144] The control device 40 may be configured to perform frost suppression control in order to suppress the formation of frost on the indoor evaporator 20 when the refrigerant pressure in the indoor evaporator 20 becomes equal to or lower than a predetermined value.

[0145] An example of frost prevention control is shown in Fig. 8. In frost prevention control, the second expansion valve 19 and the motor-operated valve 25 are fully closed. Specifically, when frost prevention control starts, the second expansion valve 19 is first fully closed, and then the motor-operated valve 25 is fully closed.

[0146] This cuts off the refrigerant supply to the indoor evaporator 20 and prevents the pressure of the indoor evaporator 20 from being equalized with the pressure of the outdoor heat exchanger 15 from the outlet side of the indoor evaporator 20, thereby suppressing a pressure drop (temperature drop) in the indoor evaporator 20 and ultimately suppressing the formation of frost on the indoor evaporator 20.

[0147] When the refrigerant temperature Te in the indoor evaporator 20 exceeds a predetermined value Te2 (e.g., 2° C.) due to the frost prevention control, the control device 40 ends the frost prevention control by throttling the second expansion valve 19 and the motor-operated valve 25. Specifically, when ending the frost prevention control, the control device 40 first sets the motor-operated valve 25 to the throttling state and then sets the second expansion valve 19 to the throttling state.

[0148] When the refrigerant pressure in the indoor evaporator 20 exceeds a predetermined value due to the frost prevention control, the control device 40 may end the frost prevention control by throttling the second expansion valve 19 and the motor-operated valve 25.

[0149] If the second expansion valve 19 were to be open while the motor-operated valve 25 was closed at the start and end of frost prevention control, high-pressure refrigerant would flow into the indoor evaporator 20 while high-pressure refrigerant would not flow out of the indoor evaporator 20, resulting in a rise in pressure. To avoid this, at the start of frost prevention control, the second expansion valve 19 is first brought to a fully closed state before the motor-operated valve 25 is brought to a fully closed state, and at the end of frost prevention control, the motor-operated valve 25 is first brought to a throttling state before the second expansion valve 19 is brought to a throttling state.

[0150] In this embodiment, hysteresis is applied to the temperature threshold value at the start of frost suppression control and the temperature threshold value at the end of frost suppression control in order to ensure control stability when switching between normal control and frost suppression control. However, the temperature threshold value at the start of frost suppression control and the temperature threshold value at the end of frost suppression control may be the same as the temperature threshold value at the end of frost suppression control without applying hysteresis to the temperature threshold value at the start of frost suppression control and the temperature threshold value at the end of frost suppression control.

[0151] In this embodiment, during normal control, the control device 40 controls the opening degree of the second expansion valve 19 to an opening degree exceeding a first predetermined opening degree and the opening degree of the motor-operated valve 25 to an opening degree exceeding a second predetermined opening degree. When the temperature of the second evaporator 20 becomes equal to or lower than a predetermined temperature Te1 that is a temperature related to the occurrence of frost in the second evaporator 20, the control device 40 performs frost suppression control by setting the opening degree of the second expansion valve 19 to an opening degree equal to or lower than the first predetermined opening degree and setting the opening degree of the motor-operated valve 25 to an opening degree equal to or lower than the second predetermined opening degree.

[0152] According to this, in the frost suppression control, the flow rate of refrigerant supplied to the second evaporator 20 is reduced by setting the opening degree of the second expansion valve 19 to a first predetermined opening degree or less, and the pressure drop and temperature drop can be suppressed by setting the opening degree of the electric valve 25 to a second predetermined opening degree or less to equalize the pressure from the downstream side of the second evaporator 20.

[0153] Therefore, when the flow rate of the refrigerant supplied to the second evaporator 20 is reduced by the second expansion valve 19 in order to suppress frosting of the second evaporator 20, a decrease in the pressure of the refrigerant in the second evaporator 20 can be suppressed, so that frosting of the second evaporator 20 can be suppressed even during transient load fluctuations, etc.

[0154] In this embodiment, when starting frost prevention control, the control device 40 sets the opening degree of the second expansion valve 19 to a first predetermined opening degree or less, and then sets the opening degree of the motor-operated valve 25 to a second predetermined opening degree or less. This makes it possible to prevent the pressure in the second evaporator 20 from increasing too much when starting frost prevention control.

[0155] In this embodiment, when terminating the frost prevention control, the control device 40 sets the opening degree of the motor-operated valve 25 to an opening degree exceeding the second predetermined opening degree, and then sets the opening degree of the second expansion valve 19 to an opening degree exceeding the first predetermined opening degree. This makes it possible to suppress an excessive increase in pressure in the second evaporator 20 when terminating the frost prevention control.

[0156] In this embodiment, the above-mentioned first predetermined opening degree is an opening degree that closes the second expansion valve 19, and the above-mentioned second predetermined opening degree is an opening degree that closes the motor-operated valve 25. This makes it possible to more reliably suppress frosting of the second evaporator 20.

[0157] Second embodiment In this embodiment, as shown in FIGS. 9 to 12, the motor-operated valve 25 is provided with a bleed port 25a. The motor-operated valve 25 is an electric variable throttle mechanism (in other words, an electric expansion valve) having a valve element 251 and an electric actuator 252. The valve element 251 changes the throttle opening of the motor-operated valve 25. The electric actuator 252 is a drive unit that displaces the valve element 251. The electric actuator 252 is a brushless DC motor having a coil 252a and a rotor 252b.

[0158] The motor-operated valve 25 includes a control board 253 , a target magnet 254 , a Hall IC unit 255 , a speed reducing mechanism 256 , a rotary-linear motion conversion mechanism 257 , and a partition wall 258 .

[0159] The control board 253 has a driver IC section. The driver IC section has an inverter and outputs a drive current to the coil 252a of the electric actuator 252. The target magnet 254 is a permanent magnet that rotates together with the rotor 252b. The Hall IC section 255 detects a change in magnetic flux accompanying the rotation of the target magnet 254. The Hall IC section 255 detects the change in magnetic flux accompanying the rotation of the target magnet 254, thereby determining the rotation state of the rotor 252b.

[0160] The speed reducing mechanism 256 reduces the speed of rotation of the rotor 252b and transmits it to the rotary-to-linear motion conversion mechanism 257. The rotary-to-linear motion conversion mechanism 257 converts the rotational motion transmitted from the rotary-to-linear motion conversion mechanism 256 into linear motion and transmits it to the valve body 251. The partition wall 258 is a member that divides the internal space of the motor-operated valve 25 into a space in which the refrigerant is present and a space in which electrical components such as the control board 253 and the coil 252a are housed. In this example, the rotor 252b, the rotary-to-linear motion conversion mechanism 257, and the rotary-to-linear motion conversion mechanism 257 are disposed in the space in which the refrigerant is present.

[0161] The operation of the electric actuator 252 is controlled by command value information relating to the opening degree of the electric expansion valve output from the control device 40. Specifically, the command value information relating to the opening degree of the electric expansion valve output from the control device 40 is output to the control board 253, and the driver IC section of the control board 253 outputs a drive current (in other words, an operating current) according to the command value information relating to the opening degree of the motor-operated valve 25 to the coil 252a.

[0162] A rotating magnetic field is created by precisely controlling the drive current applied to coil 252a, which rotates rotor 252b equipped with a permanent magnet. The rotational force is converted into vertical movement of valve body 251 via reduction mechanism 256 and rotary-to-linear conversion mechanism 257, thereby varying the opening area of ​​the refrigerant passage (in other words, the throttle opening).

[0163] The motor-operated valve 25 has a full opening function that functions simply as a refrigerant passage without exerting any refrigerant pressure reduction or flow rate adjustment action by fully opening the throttle. The motor-operated valve 25 has a full closing function that closes the refrigerant passage by fully closing the throttle. In the full closing state, the valve body 251 abuts against the valve seat 259 to close the refrigerant passage.

[0164] The bleed port 25a is a communication portion that communicates between the inlet side and the outlet side of the motor-operated valve 25 in order to prevent the valve from being completely closed even when the throttle opening is set to the fully closed state.

[0165] In a first embodiment shown in Fig. 10, bleed port 25a is a communication hole formed in valve seat 259. In a second embodiment shown in Fig. 11, bleed port 25a is a communication hole formed in valve body 251. In a second embodiment shown in Fig. 12, bleed port 25a is a chamfered portion formed in a corner of valve seat 259 that abuts against valve body 251.

[0166] In any of the first to third embodiments, the diameter of the bleed port 25a (in other words, the port cross-sectional area) is set to a size that can suppress the pressure drop (temperature drop) of the indoor evaporator 20 when the motor-operated valve 25 is fully closed during frost suppression control.

[0167] In this embodiment, the motor-operated valve 25 is provided with the bleed port 25a, so that the indoor evaporator 20 can be prevented from becoming a completely closed space even if the second expansion valve 19 and the motor-operated valve 25 are fully closed during frost prevention control. Therefore, even if the refrigerant temperature rises with a large amount of liquid refrigerant inside the indoor evaporator 20 during frost prevention control, it is possible to prevent a sudden increase in the internal pressure of the indoor evaporator 20 and adverse effects on the durability of the indoor evaporator 20.

[0168] In this embodiment, the motor-operated valve 25 has a bleed port 25a that ensures a predetermined opening area even when the valve is closed.

[0169] This makes it possible to prevent the inside of the second evaporator 20 from becoming a completely closed space when the motor-operated valve 25 is closed during frost suppression control, thereby preventing the pressure inside the second evaporator 20 from rising suddenly.

[0170] Third embodiment In the above embodiment, in the second parallel dehumidification mode, the control device 40 feedback controls the opening degree of the motor-operated valve 25 so that the evaporation pressure of the indoor evaporator 20 approaches the target value. In the present embodiment, the control device 40 does not perform feedback control at the beginning of the startup of the refrigeration cycle apparatus 10 (i.e., the beginning of the startup of the compressor 11), immediately after switching of the operation mode of the refrigeration cycle apparatus 10, or when the air conditioning load fluctuates significantly, and appropriately controls the evaporation pressure of the indoor evaporator 20 by determining the opening degree of the motor-operated valve 25 to the target opening degree predicted from the air conditioning load.

[0171] Immediately after the operation mode of the refrigeration cycle device 10 is switched, specifically, means immediately after switching from an operation mode in which the evaporation pressure of the indoor evaporator 20 is not controlled by the motor valve 25, such as the heating mode, to the second parallel dehumidification mode in which the evaporation pressure of the indoor evaporator 20 is controlled by the motor valve 25.

[0172] A large change in the air conditioning load occurs, for example, when the temperature of the intake air to the interior evaporator 20, the amount of intake air, or the interior air conditioning temperature setting Tset changes significantly.

[0173] That is, when the evaporation pressure of the indoor evaporator 20 cannot be appropriately controlled by controlling the motor-operated valve 25 through feedback control, the opening degree of the motor-operated valve 25 is determined to be a target opening degree predicted from the air-conditioning load.

[0174] The opening degree predicted from the air conditioning load is the opening degree predicted based on the intake air temperature to the interior evaporator 20, the intake air volume, the air conditioning interior set temperature Tset, and the target evaporation pressure or evaporation temperature of the interior evaporator 20.

[0175] Specifically, the higher the intake air temperature to the indoor evaporator 20, the greater the refrigerant flow rate to the indoor evaporator 20, so the opening of the motor-operated valve 25 is increased to set the evaporation pressure of the indoor evaporator 20 to the target value.

[0176] The greater the amount of air drawn into the indoor evaporator 20, the greater the amount of refrigerant flowing to the indoor evaporator 20. Therefore, the opening of the motor-operated valve 25 is increased to set the evaporation pressure of the indoor evaporator 20 to a target value.

[0177] The higher the air conditioning interior temperature setting Tset, the higher the rotation speed of the compressor 11 is to increase the heating capacity, and the greater the refrigerant flow rate to the interior evaporator 20 is. Therefore, the opening of the motor-operated valve 25 is increased to set the evaporation pressure of the interior evaporator 20 to the target value.

[0178] The higher the target evaporation pressure or evaporation temperature of the indoor evaporator 20, the smaller the opening of the motor-operated valve 25 is made to ensure a difference with the evaporation pressure or evaporation temperature of the outdoor heat exchanger 15.

[0179] FIG. 13 shows an example of control when the temperature of the air suctioned into the interior evaporator 20 changes suddenly. Specifically, a control example is shown when the inside / outside air switching device 33 switches from a state in which inside air (inside air at 25° C. in this example) is introduced to a state in which outside air (outside air at 5° C. in this example) is introduced.

[0180] When inside air is being introduced, feedback control is performed. When the introduction of inside air is switched to the introduction of outside air, the feedback control is terminated and the opening of the motor-operated valve 25 is determined to be the target opening predicted from the air conditioning load. When the opening of the motor-operated valve 25 reaches the target opening predicted from the air conditioning load, feedback control is performed again.

[0181] By determining the target opening degree predicted from the air conditioning load, the opening degree of the motor-operated valve 25 can be changed quickly when it is necessary to suddenly change the opening degree of the motor-operated valve 25. Therefore, the evaporation pressure of the indoor evaporator 20 can be appropriately controlled even if the air conditioning load suddenly changes.

[0182] (Fourth embodiment) In this embodiment, as shown in FIG. 14, a fourth refrigerant passage 28 is connected to the third refrigerant passage 18, which guides the refrigerant flowing out from the outdoor heat exchanger 15 to the inlet side of the accumulator 21 via the third expansion valve 26 and the chiller 27.

[0183] The third expansion valve 26 is a third pressure reducing section configured to be able to change the passage area (throttle opening) of the fourth refrigerant passage 28. More specifically, the third expansion valve 26 is an electric variable throttle mechanism including a valve body configured to be able to change the passage opening (throttle opening) of the fourth refrigerant passage 28, and an electric actuator made of a stepping motor that changes the throttle opening of the valve body.

[0184] The third expansion valve 26 of the present embodiment is configured as a variable throttling mechanism with a full opening function that fully opens the fourth refrigerant passage 28 when the throttling opening is fully opened, and a full closing function that closes the fourth refrigerant passage 28 when the throttling opening is fully closed. In other words, the third expansion valve 26 can be made not to exert a decompression effect on the refrigerant, and can open and close the fourth refrigerant passage 28. The operation of the third expansion valve 26 is controlled by a control signal output from the control device 40.

[0185] The outlet side of the third expansion valve 26 is connected to the inlet side of the chiller 27. The chiller 27 is disposed in the low-temperature coolant circuit 50, and is an evaporator that, in the battery cooling mode or the like, evaporates the refrigerant flowing therethrough by heat exchange with the coolant circulating through the low-temperature coolant circuit 50, thereby exerting a heat absorption effect to cool the air to be blown into the vehicle cabin.

[0186] The coolant in the low-temperature coolant circuit 50 is a fluid that serves as a heat medium. In this embodiment, a liquid that contains at least ethylene glycol, dimethylpolysiloxane, or a nanofluid, or an antifreeze liquid is used as the coolant in the low-temperature coolant circuit 50. The low-temperature coolant circuit 50 is a low-temperature heat medium circuit in which a low-temperature heat medium circulates.

[0187] The low-temperature cooling water circuit 50 is arranged with a chiller 27, a low-temperature side pump 51, and a battery cooler 52. The low-temperature side pump 51 is a heat medium pump that draws in and discharges cooling water. The low-temperature side pump 51 is an electric pump. The low-temperature side pump 51 is a low-temperature side flow rate adjustment unit that adjusts the flow rate of cooling water circulating through the low-temperature cooling water circuit 50. The battery cooler 52 is a cooler that cools the battery with the cooling water circulating through the low-temperature cooling water circuit 50.

[0188] The vehicle air conditioner 1 of this embodiment can be switched to a heating mode, a cooling mode, and a dehumidifying heating mode, as in the above embodiment. The vehicle air conditioner 1 of this embodiment can also be switched to a battery cooling mode in which the battery cooler 52 is cooled by the cooling water cooled by the chiller 27.

[0189] Furthermore, the vehicle air conditioner 1 of this embodiment can be switched between a heating / battery cooling mode, a cooling / battery cooling mode, and a dehumidifying / heating / battery cooling mode.

[0190] The heating / battery cooling mode is an operation mode that simultaneously performs heating and cooling of the battery cooler 52. The cooling / battery cooling mode is an operation mode that simultaneously performs cooling and cooling of the battery cooler 52. The dehumidifying / heating / battery cooling mode is an operation mode that simultaneously performs dehumidifying heating and cooling of the battery cooler 52.

[0191] Among these operation modes, the air conditioning battery cooling mode will be described in detail below, and detailed descriptions of the other operation modes will be omitted.

[0192] In the air-conditioning battery cooling mode, the control device 40 closes the second refrigerant passage 16 with the first on-off valve 17, and closes the bypass passage 22 with the second on-off valve 23. Furthermore, the first refrigerant passage 13 is fully opened with the first expansion valve 14. As a result, the refrigeration cycle device 10 is switched to the first refrigerant passage through which the refrigerant flows as shown by the outlined arrow in FIG.

[0193] With this refrigerant flow path configuration, the control device 40 determines the operating states of various control devices connected to the control device 40 (control signals to be output to various control devices) based on the target blowing temperature TAO, detection signals from the sensor group, etc.

[0194] For example, the refrigerant discharge capacity of the compressor 11, i.e., the control signal output to the electric motor 11b of the compressor 11, is determined as follows. First, a target evaporator outlet temperature TEO of the blown air from the indoor evaporator 20 is determined based on the target outlet temperature TAO, with reference to a control map stored in advance in the control device 40. Therefore, among the control routines executed by the control device 40, the control step of determining the target evaporator outlet temperature TEO constitutes a target evaporator outlet temperature determination means.

[0195] Then, based on the deviation between the target evaporator discharge temperature TEO and the detection value of the evaporator temperature sensor, a control signal is determined using a feedback control technique to be output to the electric motor 11b of the compressor 11 so that the temperature of the air passing through the indoor evaporator 20 approaches the target discharge temperature TAO.

[0196] Moreover, the control signal output to the second expansion valve 19 is determined so that the degree of superheat of the refrigerant on the outlet side of the indoor evaporator 20 approaches a predetermined target degree of superheat.

[0197] In addition, the control signal output to the third expansion valve 26 is determined so that the degree of subcooling of the refrigerant flowing into the third expansion valve 26 approaches a predetermined target degree of subcooling so as to bring the COP closer to the maximum value.

[0198] The control signal output to motor-operated valve 25 is determined so as to be fully open during normal control. The control signal output to motor-operated valve 25 is determined so as to be a throttle opening degree at which the refrigerant evaporation pressure in indoor evaporator 20 is maintained at or above a predetermined value and frost does not form on indoor evaporator 20 during high battery cooling control.

[0199] In addition, the control signal output to the servo motor of the air mix door 36 is determined so that the air mix door 36 blocks the air passage of the heater core 34 and the indoor condenser 12, and the total flow rate of the blown air after passing through the indoor evaporator 20 passes through the cold air bypass passage 35.

[0200] Therefore, in the air-conditioning battery cooling mode, the refrigeration cycle device 10 receives the high-pressure refrigerant discharged from the compressor 11 and flows into the interior condenser 12. At this time, the air mix door 36 closes the air passages of the heater core 34 and the interior condenser 12, so the refrigerant that flows into the interior condenser 12 flows out of the interior condenser 12 with almost no heat exchange with the air blown into the vehicle cabin.

[0201] The refrigerant flowing out from the indoor condenser 12 flows into the first expansion valve 14 via the first refrigerant passage 13. At this time, since the first expansion valve 14 fully opens the first refrigerant passage 13, the refrigerant flowing out from the indoor condenser 12 flows into the outdoor heat exchanger 15 without being depressurized by the first expansion valve 14. Then, the refrigerant that has flowed into the outdoor heat exchanger 15 dissipates heat in the outdoor heat exchanger 15 to the outside air blown by the blower fan.

[0202] The refrigerant flowing out from the exterior heat exchanger 15 flows into the second expansion valve 19 via the third refrigerant passage 18, where it is reduced in pressure and expanded to become a low-pressure refrigerant. The low-pressure refrigerant reduced in pressure by the second expansion valve 19 flows into the interior evaporator 20, where it absorbs heat from the air blown into the vehicle compartment by the blower 32 and evaporates. This cools the air blown into the vehicle compartment.

[0203] The refrigerant flowing out from the indoor evaporator 20 flows into the accumulator 21 and is separated into gas and liquid. Then, the gas-phase refrigerant separated in the accumulator 21 is sucked into the suction side of the compressor 11 and compressed again by the compressor 11. The liquid-phase refrigerant separated in the accumulator 21 is stored inside the accumulator 21 as surplus refrigerant that is not required for the cycle to exhibit the required refrigeration capacity.

[0204] As described above, in the air-conditioning battery 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.

[0205] As described above, the control signal output to the motor-operated valve 25 is determined to be fully open during normal control, and during high battery cooling control, the throttle opening is determined to be such that the refrigerant evaporation pressure in the indoor evaporator 20 is maintained above a predetermined value and frost does not form on the indoor evaporator 20.

[0206] 15 and 16 are diagrams comparing the difference in cooling temperature during normal control and during high battery cooling control. Normal control is control in which motor-operated valve 25 is fully opened. High battery cooling control is control in which motor-operated valve 25 is controlled to a throttle opening that prevents frost from forming on indoor evaporator 20.

[0207] In FIG. 16, Q is the battery cooling amount, K1 is the thermal resistance of battery cooler 52, and K2 is the thermal resistance of chiller 27.

[0208] 15-16, the refrigerant temperature of chiller 27 during high battery cooling control (-5°C in this example) is lower than the refrigerant temperature of chiller 27 during normal control (0°C in this example), so there is a larger temperature difference between the cooling water flowing into chiller 27 and the refrigerant in chiller 27. As a result, the cooling capacity of chiller 27 is improved, so the batteries can be cooled with high capacity.

[0209] (Other embodiments) Although the embodiment of the present invention has been described above, the present invention is not limited to this, and is not limited to the wording of each claim as long as it does not deviate from the scope of each claim, and includes a range that can be easily substituted by a person skilled in the art, and improvements based on the knowledge that a person skilled in the art normally possesses can be appropriately added. For example, various modifications are possible as follows.

[0210] (1) The control of the first expansion valve 14 and the second expansion valve 19 in the above embodiment is shown as an example, and the present invention is not limited to this.

[0211] For example, in the second dehumidification heating mode of the above first embodiment, an example has been shown in which the first expansion valve 14 is controlled so that the degree of subcooling of the refrigerant flowing into the first expansion valve 14 approaches a target degree of subcooling, and the second expansion valve 19 is controlled so that the degree of superheat of the refrigerant at the outlet side of the indoor evaporator 20 approaches a predetermined target degree of superheat.

[0212] In response to this, the first expansion valve 14 may be controlled so that the degree of superheat of the refrigerant at the outlet side of the indoor evaporator 20 approaches a predetermined target degree of superheat, and the second expansion valve 19 may be controlled so that the degree of subcooling of the refrigerant flowing into the second expansion valve 19 approaches the target degree of subcooling.

[0213] (2) In the above-described embodiments, the heating mode, the cooling mode, and the dehumidifying and heating mode are switched by the operation signal of the A / C switch. However, the present invention 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 and heating mode may be switched in response to the operation signal of the operation mode setting switch.

[0214] (3) In each of the above-described embodiments, an example has been described in which the control device 40 operates the air mix door 36 to block either the air passage of the indoor condenser 12 and the heater core 34, or the cold air bypass passage 35 during each of the operating modes of the heating mode, the cooling mode, and the dehumidification heating mode. However, the operation of the air mix door 36 is not limited to this.

[0215] For example, the air mix door 36 may open both the air passage of the interior condenser 12 and the heater core 34 and the cold air bypass passage 35. The temperature of the air blown into the vehicle cabin may be adjusted by adjusting the ratio of the air volume passing through the air passage of the interior condenser 12 and the heater core 34 to the air volume passing through the cold air bypass passage 35. Such temperature adjustment is effective in that it is easy to finely adjust the temperature of the air blown into the vehicle cabin.

[0216] (4) In each of the above-described embodiments, the heater core 34 is disposed inside the indoor air conditioning unit 30. However, in cases where an external heat source such as an engine is insufficient, the heater core 34 may be eliminated or replaced with an electric heater, etc.

[0217] (5) In each of the above-described embodiments, the refrigeration cycle device 10 of the present invention is applied to a vehicle air conditioner 1. However, the present invention is not limited to this. For example, the refrigeration cycle device 10 may be applied to a stationary air conditioner or the like. [Explanation of symbols]

[0218] 11 Compressor 12 Indoor condenser (radiator) 14 First expansion valve (first pressure reducing section) 15 Outdoor heat exchanger (first evaporator) 19 Second expansion valve (second pressure reducing section) 20 Indoor evaporator (second evaporator) 25 Motor-operated valve (opening adjustment section) 25a Bleed port 40 Control device (control unit)

Claims

1. A compressor (11) that draws in, compresses, and discharges a refrigerant; a radiator (12) that radiates heat from the refrigerant discharged from the compressor; a first pressure reducing section (14) for reducing the pressure of the refrigerant whose heat has been radiated by the radiator; a first evaporator (15) for decompressing the refrigerant decompressed in the first decompression section; a second pressure reducing section (19) arranged in parallel with the first pressure reducing section in the flow of the refrigerant and reducing the pressure of the refrigerant whose heat has been radiated by the radiator; a second evaporator (20) for decompressing the refrigerant decompressed in the second decompression section; an opening adjustment unit (25) that adjusts an opening of the refrigerant flow path downstream of the second evaporator, the opening adjustment unit being parallel to the first evaporator; a control unit (40) that controls the opening degree of the first pressure reducing unit and the opening degree adjusting unit, The control unit is During normal control, the opening degree of the second pressure reducing unit is controlled to be greater than a first predetermined opening degree, and the opening degree of the opening degree adjusting unit is controlled to be greater than a second predetermined opening degree, A refrigeration cycle device that performs frost suppression control in which, when the temperature of the second evaporator falls below a predetermined temperature (Te1) that is a temperature related to the occurrence of frost in the second evaporator, the opening degree of the second pressure reduction section is set to below the first predetermined opening degree and the opening degree of the opening adjustment section is set to below the second predetermined opening degree.

2. 2. The refrigeration cycle apparatus according to claim 1, wherein when starting the frost suppression control, the control unit sets the opening degree of the second pressure reduction unit to the first predetermined opening degree or less, and then sets the opening degree of the opening degree adjustment unit to the second predetermined opening degree or less.

3. 3. The refrigeration cycle apparatus according to claim 2, wherein when terminating the frost suppression control, the control unit sets the opening degree of the opening degree adjustment unit to an opening degree greater than the second predetermined opening degree, and then sets the opening degree of the second pressure reduction unit to an opening degree greater than the first predetermined opening degree.

4. The second pressure reducing unit has a valve capable of fully closing a flow path of the refrigerant, The opening degree adjustment unit has a valve that can fully close the flow path of the refrigerant, the first predetermined opening degree is an opening degree for closing the second pressure reducing unit, 4. The refrigeration cycle apparatus according to claim 1, wherein the second predetermined opening degree is an opening degree that closes the opening degree adjustment unit.

5. 5. The refrigeration cycle apparatus according to claim 4, wherein the opening degree adjusting portion has a bleed port (25a) that ensures a predetermined opening area even when the valve is closed.

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