Heat pump cycle device

Abstract

This heat pump cycle device has a compressor (11), a branch part (12a), a heating part (15), low-temperature-side decompression parts (19, 26, 27), a bypass passage (13), a bypass-side decompression part (14), merging parts (12b, 25), a heat absorption part (20), and a control unit (70). The control unit performs control for switching between a first heating mode and a second heating mode. In the first heating mode, all refrigerant discharged from a compressor is caused to flow into the heating part via the branch part, heat absorbed by the heat absorption part from a heat absorption object is pumped up, and an object to be heated is heated. In the second heating mode, some of the refrigerant discharged from the compressor is caused to flow into the bypass passage via the branch part, and the refrigerant flowing out from the bypass-side decompression part is guided to the merging parts. When switching from the first heating mode to the second heating mode, the control unit executes a limiting operation for limiting a heat dissipation amount in the heating unit in the first heating mode to be low, and then, after executing the limiting operation, completes switching to the second heating mode.

Description

Heat pump cycle device CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application is based on Japanese Patent Application No. 2023-109418 filed on July 3, 2023, the contents of which are incorporated herein by reference.

[0002] The present disclosure relates to a heat pump cycle device.

[0003] A heat pump cycle device has been applied to a vehicle air conditioner, and a heat pump heating mode has been realized in which heat absorbed from an external heat source is used to heat an object to be heated. Specifically, a vehicle air conditioner having a heat pump heating mode in which the object to be heated is the ventilation air supplied to the vehicle compartment is known.

[0004] The heating capacity in this heat pump heating mode is affected by the amount of heat absorbed from the heat sink, so if the amount of heat absorbed from the heat sink is low compared to the required heating capacity, it is possible that the object to be heated cannot be heated sufficiently. For example, if outside air is used as the heat sink, sufficient heating capacity (i.e., heating capacity) cannot be achieved in an environment with a low outside temperature.

[0005] In such a case, the heat pump cycle apparatus employs an operating mode in which a portion of the heat of the high-pressure refrigerant discharged from the compressor is utilized to increase the workload of the compressor, thereby exerting the heating capacity of the object to be heated. As a technology relating to a heat pump cycle apparatus having these two operating modes, the technology described in Patent Document 1 is known.

[0006] The vehicle air conditioning system of Patent Document 1 is configured to be switchable between a heat pump heating mode, which corresponds to a heat pump heating mode, and a hot gas heating mode. The hot gas heating mode is an operating mode in which a portion of the refrigerant discharged from the compressor is bypassed to the low-pressure side, thereby increasing the workload of the compressor itself and demonstrating the heating capacity of the object to be heated (i.e., the blown air).

[0007] Japanese Patent Application Laid-Open No. 2021-156567

[0008] Here, if the operation mode is simply switched from the heat pump heating mode to an operation mode in which part of the heat contained in the refrigerant discharged from the compressor is used to increase the workload of the compressor and thereby increase the heating capacity, it is expected that the heating capacity of the object to be heated will decrease.

[0009] Taking the heat pump heating mode and hot gas heating mode of Patent Document 1 as examples, in hot gas heating mode, the heating capacity of the object to be heated is determined by the workload of the compressor. The workload of the compressor is proportional to the refrigerant flow rate in the compressor, which in turn is proportional to the suction density of the refrigerant into the compressor. Therefore, in order to increase the heating capacity in hot gas heating mode, it is important to increase the suction density of the refrigerant into the compressor. In other words, it is necessary to increase the suction pressure of the refrigerant into the compressor.

[0010] On the other hand, in the heat pump heating mode, the heating capacity of the object to be heated corresponds to the amount of heat absorbed by the heat absorber, and the amount of heat absorbed by the heat absorber corresponds to the temperature difference between the temperature of the low-pressure refrigerant flowing through the heat absorber and the temperature of the heat absorption object. Therefore, in order to increase the heating capacity in the heat pump heating mode, it is necessary to lower the pressure of the low-pressure refrigerant in the heat absorber as much as possible relative to the standard determined by the temperature of the heat absorption object.

[0011] In this way, in hot gas heating mode, the higher the low pressure in the cycle, the more heating capacity can be ensured, whereas in heat pump heating mode, the lower the low pressure in the cycle, the more heating capacity can be ensured.

[0012] When switching between the heat pump heating mode and the hot gas heating mode, which have opposing characteristics, fluctuations in heating capacity may occur due to differences in the required conditions. For example, when switching from heat pump heating mode to hot gas heating mode, if the cycle low-pressure pressure is low, the heating capacity required for hot gas heating may be insufficient, causing fluctuations in heating capacity when the mode is switched. Furthermore, when switching to hot gas heating mode under these conditions, the low-pressure pressure must be increased to make up for the shortage, and it is expected that there will be a period of insufficient heating capacity in order to achieve the same heating capacity as before the switch.

[0013] In view of the above, the present disclosure aims to provide a heat pump cycle device that can suppress fluctuations in heating capacity when switching from a heat pump heating mode to an operating mode that utilizes part of the heat contained in the high-pressure refrigerant discharged from the compressor to exert heating capacity.

[0014] The heat pump cycle device according to the first aspect of the present disclosure includes a compressor, a branching section, a heating section, a low-temperature side pressure reducing section, a bypass passage, a bypass side pressure reducing section, a junction section, a heat absorption section, and a control section.

[0015] The compressor compresses and discharges the refrigerant. The branching section branches the flow of refrigerant discharged from the compressor. The heating section heats an object to be heated using the refrigerant flowing out from one outlet of the branching section as a heat source. The low-temperature side pressure reduction section reduces the pressure of the refrigerant flowing out from the heating section. The bypass passage circulates the other refrigerant branched at the branching section. The bypass side pressure reduction section reduces the pressure of the refrigerant flowing through the bypass passage. The confluence section merges the flow of refrigerant flowing out from the bypass side pressure reduction section and the flow of refrigerant flowing out from the low-temperature side pressure reduction section, and causes them to flow out to the suction port side of the compressor. The heat absorption section absorbs heat from the object to be heat absorbed by at least the refrigerant flowing out from the low-temperature side pressure reduction section.

[0016] The control unit controls switching between a first heating mode and a second heating mode. In the first heating mode, all of the refrigerant discharged from the compressor flows into the heating unit via the branch unit, and the heat absorbed from the heat absorption object is pumped up by the heat absorption unit to heat the object. In the second heating mode, a portion of the refrigerant discharged from the compressor flows into the bypass passage via the branch unit, and the refrigerant flowing out from the bypass-side pressure reduction unit is guided to the junction unit. At the same time, in the second heating mode, the other portion of the refrigerant discharged from the compressor flows into the heating unit via the branch unit, and the refrigerant flowing out from the heating unit is merged with the refrigerant flowing from the bypass-side pressure reduction unit at the junction unit and is drawn into the compressor.

[0017] When switching from the first heating mode to the second heating mode, the control unit performs a restriction operation to limit the amount of heat dissipation in the heating unit in the first heating mode to a low level, and after performing the restriction operation, completes the switch to the second heating mode.

[0018] Therefore, according to the heat pump cycle apparatus of the first aspect, by executing the limiting operation when switching from the first heating mode to the second heating mode and suppressing the amount of heat dissipated from the refrigerant in the heating unit, it is possible to increase the amount of heat contained in the refrigerant immediately before switching to the second heating mode. As a result, the heat pump cycle apparatus of the first aspect can minimize the difference in heating capacity between the first heating mode and the second heating mode, and can suppress fluctuations in heating capacity.

[0019] Furthermore, the heat pump cycle device according to the second aspect of the present disclosure includes a compressor, a branching section, a heating section, a low-temperature side pressure reducing section, a bypass passage, a bypass side pressure reducing section, a confluence section, a heat absorption section, and a control section.

[0020] The compressor compresses and discharges the refrigerant. The branching section branches the flow of refrigerant discharged from the compressor. The heating section heats an object to be heated using the refrigerant flowing out from one outlet of the branching section as a heat source. The low-temperature side pressure reduction section reduces the pressure of the refrigerant flowing out from the heating section. The bypass passage circulates the other refrigerant branched at the branching section. The bypass side pressure reduction section reduces the pressure of the refrigerant flowing through the bypass passage. The confluence section combines the flow of refrigerant flowing out from the bypass side pressure reduction section and the flow of refrigerant flowing out from the low-temperature side pressure reduction section, and causes the refrigerant to flow out to the suction port side of the compressor. The heat absorption section absorbs heat from the object to be heat absorbed by at least the refrigerant flowing out from the low-temperature side pressure reduction section.

[0021] The control unit controls switching between a first heating mode and a second heating mode. In the first heating mode, all of the refrigerant discharged from the compressor flows into the heating unit via the branch unit, and the heat absorbed from the heat absorption object is pumped up by the heat absorption unit to heat the object. In the second heating mode, a portion of the refrigerant discharged from the compressor flows into the bypass passage via the branch unit, and the refrigerant flowing out from the bypass-side pressure reduction unit is guided to the junction unit. At the same time, in the second heating mode, the other portion of the refrigerant discharged from the compressor flows into the heating unit via the branch unit, and the refrigerant flowing out from the heating unit is merged with the refrigerant flowing from the bypass-side pressure reduction unit at the junction unit and drawn into the compressor.

[0022] When switching from the first heating mode to the second heating mode, the control unit executes a heat absorption amount ensuring operation to ensure the amount of heat absorption in the heat absorption unit by using the heat of the refrigerant discharged from the compressor and the heat absorbed by the heat absorption unit from the heat absorption object. After executing the heat absorption amount ensuring operation, the control unit completes the switching to the second heating mode.

[0023] Therefore, according to the heat pump cycle apparatus of the second aspect, by performing the heat absorption amount ensuring operation when switching from the first heating mode to the second heating mode and ensuring the amount of heat absorption by the refrigerant, it is possible to increase the heat amount of the refrigerant immediately before switching to the second heating mode. As a result, the heat pump cycle apparatus of the second aspect can minimize the difference in heating capacity between the first heating mode and the second heating mode, and can suppress fluctuations in heating capacity.

[0024] A heat pump cycle device according to a third aspect of the present disclosure includes a heat pump cycle, a heat medium circuit, and a control unit. The heat pump cycle includes a compressor, a heat medium-refrigerant heat exchanger, a pressure reduction unit, and a chiller. The compressor compresses and discharges a refrigerant. The heat medium-refrigerant heat exchanger dissipates heat from the high-pressure refrigerant discharged from the compressor to the heat medium. The pressure reduction unit reduces the pressure of the refrigerant flowing out from the heat medium-refrigerant heat exchanger. The chiller exchanges heat between the refrigerant decompressed in the pressure reduction unit and the heat medium, causing the refrigerant to absorb heat.

[0025] The heat medium circuit includes a first circuit, a second circuit, a heat medium connecting flow path, and a flow rate adjuster. The first circuit is configured to allow the heat medium flowing out of the heat medium-refrigerant heat exchanger to circulate, and includes a heat medium radiator that radiates heat from the heat medium to a heated object. The second circuit is configured to allow the heat medium flowing through the chiller to circulate, and includes a heat medium heat absorber that absorbs heat from a heat absorption object through heat exchange with the heat medium. The heat medium connecting flow path connects the first circuit and the second circuit to allow the heat medium to flow in and out. The flow rate adjuster adjusts the flow rate of the heat medium flowing in and out between the first circuit and the second circuit via the heat medium connecting flow path.

[0026] The control unit controls switching between an independent circulation heating mode and a circuit-linked heating mode. In the independent circulation heating mode, heat from the heat absorption object is absorbed and pumped from the heat medium circulating independently through the second circuit, and the object to be heated is heated in the heat medium radiator via the heat medium circulating independently through the first circuit. In the circuit-linked heating mode, a portion of the heat medium that has circulated through the heat medium refrigerant heat exchanger is circulated through the chiller via the heat medium connection flow path, and another portion of the heat medium that has circulated through the heat medium refrigerant heat exchanger is circulated through the first circuit via the heat medium radiator, and the object to be heated is heated in the heat medium radiator.

[0027] When switching from the independent circulation heating mode to the circuit-linked heating mode, the control unit performs a restriction operation to limit the amount of heat dissipation in the heat medium radiator in the independent circulation heating mode to a low level, and after performing the restriction operation, completes the switch to the circuit-linked heating mode.

[0028] Therefore, according to the heat pump cycle apparatus of the third aspect, the limiting operation is performed when switching from the independent circulation heating mode to the circuit-linked heating mode, and the amount of heat radiated from the heat medium radiator is reduced, thereby increasing the amount of heat in the refrigerant immediately before switching to the circuit-linked heating mode. As a result, the heat pump cycle apparatus of the third aspect can minimize the difference in heating capacity between the independent circulation heating mode and the circuit-linked heating mode, thereby suppressing fluctuations in heating capacity.

[0029] The above and other objects, features, and advantages of the present disclosure will become more apparent from the following detailed description with reference to the accompanying drawings.

[0016] Fig. 1 is a configuration diagram of a heat pump cycle device according to a first embodiment. Fig. 2 is a configuration diagram of an indoor air conditioning unit according to the first embodiment. Fig. 3 is a block diagram showing a control system of the heat pump cycle device according to the first embodiment. Fig. 4 is a Mollier diagram of the heat pump cycle device according to the first embodiment during heat pump heating operation. Fig. 5 is a Mollier diagram of the heat pump cycle device according to the first embodiment during hot gas heating operation. Fig. 6 is an explanatory diagram showing an example of switching control in the heat pump cycle device according to the first embodiment. Fig. 7 is a configuration diagram of a heat pump cycle device according to a second embodiment. Fig. 8 is an explanatory diagram showing a first state of switching control in the heat pump cycle device according to the second embodiment. Fig. 9 is an explanatory diagram showing a second state of switching control in the heat pump cycle device according to the second embodiment. Fig. 10 is a configuration diagram of a heat pump cycle device according to a third embodiment. Fig. 11 is an explanatory diagram showing a first state of switching control in the heat pump cycle device according to the third embodiment. Fig. 12 is an explanatory diagram showing a second state of switching control in the heat pump cycle device according to the third embodiment. Fig. 13 is a configuration diagram of a heat pump cycle device according to a fourth embodiment. Fig. 14 is an explanatory diagram of the operation of the heat pump cycle device according to the fourth embodiment during independent circulation heating operation. Fig. 15 is an explanatory diagram of the operation of the heat pump cycle device according to the fourth embodiment during circuit-linked heating operation. FIG. 10 is an explanatory diagram showing an example of switching control of a heat pump cycle device according to a fourth embodiment.

[0030] Hereinafter, several embodiments for carrying out the present disclosure will be described with reference to the drawings. In each embodiment, parts corresponding to matters described in the preceding embodiment may be assigned the same reference numerals, and duplicate descriptions may be omitted. In each embodiment, when only a part of the configuration is described, other previously described embodiments may be applied to the other parts of the configuration. In addition to combinations of parts that are specifically specified as being combinable in each embodiment, it is also possible to partially combine embodiments even if not specified, as long as there is no particular problem with the combination.

[0031] First Embodiment A first embodiment of a heat pump cycle device according to the present disclosure will be described with reference to Figures 1 to 6. In the first embodiment, the heat pump cycle device according to the present disclosure is applied to a vehicle air conditioner 1 mounted on an electric vehicle. An electric vehicle is a vehicle that obtains driving power for traveling from an electric motor.

[0032] The vehicle air conditioner 1 according to the first embodiment includes a heat pump cycle 10, a heat medium circuit 30, an interior air conditioning unit 60, a control device 70, etc., and performs air conditioning of the interior of a vehicle, which is a space to be air-conditioned.

[0033] Next, a schematic configuration of the vehicle air conditioner 1 according to the first embodiment will be described. First, the configuration of a heat pump cycle 10 in the vehicle air conditioner 1 according to the first embodiment will be described with reference to FIG.

[0034] The heat pump cycle 10 of the vehicle air conditioner 1 according to the first embodiment is a vapor compression refrigeration cycle that adjusts the temperature of the air blown into the vehicle compartment and the heat medium circulating through the heat medium circuit 30 .

[0035] The heat pump cycle 10 is configured to be able to switch refrigerant circuits according to various operating modes to air-condition the vehicle cabin. The heat pump cycle 10 employs an HFO refrigerant (specifically, R1234yf) as the refrigerant. The heat pump cycle 10 constitutes a subcritical refrigeration cycle in which the pressure of the high-pressure side refrigerant does not exceed the critical pressure of the refrigerant.

[0036] The refrigerant is mixed with refrigerating machine oil to lubricate the compressor 11. The refrigerating machine oil is PAG oil (i.e., polyalkylene glycol oil) or POE (i.e., polyol ester) that is compatible with the liquid-phase refrigerant. A portion of the refrigerating machine oil circulates through the heat pump cycle 10 together with the refrigerant.

[0037] As shown in FIG. 1 , a heat pump cycle 10 according to the first embodiment includes a compressor 11, a bypass passage 13, a bypass-side expansion valve 14, an indoor condenser 16, a receiver 18, a low-temperature-side expansion valve 19, and a chiller 21.

[0038] The compressor 11 draws in, compresses, and discharges refrigerant in the heat pump cycle 10. The compressor 11 is an electric compressor that rotates a fixed-displacement compression mechanism with a fixed discharge capacity using an electric motor. The refrigerant discharge capacity (i.e., rotation speed) of the compressor 11 is controlled by a control signal output from the control device 70.

[0039] The compressor 11 is disposed in a drive unit compartment formed in the front of the vehicle interior. The drive unit compartment forms a space in which at least some of the equipment used to generate and adjust the driving force for the vehicle (for example, a motor generator that serves as an electric motor for driving the vehicle) is disposed.

[0040] The inlet side of a branching portion 12a formed as a three-way joint is connected to the discharge port of the compressor 11. The branching portion 12a has three inlet and outlet ports that communicate with each other. The branching portion 12a may be a joint formed by joining multiple pipes or a joint formed by providing multiple refrigerant passages in a metal block or a resin block.

[0041] The heat pump cycle 10 according to the first embodiment has a junction 12b formed in the shape of a three-way joint. Similar to the branching section 12a, the junction 12b has a basic configuration in which three inlet and outlet ports communicate with each other.

[0042] That is, when one of the three inlet / outlet ports in the three-way joint is used as an inlet and the remaining two are used as outlet ports, it functions as a branching portion that branches the refrigerant flow. Also, when two of the three inlet / outlet ports are used as inlet ports and the remaining one is used as an outlet port, it functions as a merging portion that merges the refrigerant flows. The branching portion 12a is a branching portion that branches the flow of the refrigerant discharged from the compressor 11.

[0043] One outlet of the branching portion 12a is connected to the inlet side of an interior condenser 16 that constitutes the heating portion 15. The other outlet of the branching portion 12a is connected, via a bypass passage 13, to one inlet side of a junction portion 12b that is formed in the shape of a three-way joint.

[0044] The bypass passage 13 is a refrigerant passage that guides the flow of high-pressure refrigerant discharged from the compressor 11 and flowing out from the other outlet of the branching portion 12 a to one inlet of the merging portion 12 b. As shown in FIG. 1 , a bypass-side expansion valve 14 is disposed in the bypass passage 13.

[0045] The bypass-side expansion valve 14 is a pressure reducing part on the bypass passage 13 side that reduces the pressure of the high-pressure refrigerant flowing out from the other outlet of the branching part 12 a (i.e., the other discharged refrigerant branched at the branching part 12 a) in, for example, a hot gas heating mode among various operation modes. The bypass-side expansion valve 14 can also be referred to as a flow rate adjusting part on the bypass side that adjusts the flow rate (mass flow rate) of the refrigerant flowing through the bypass passage 13.

[0046] The bypass side expansion valve 14 is an electric variable throttle mechanism having a valve element that changes the throttle opening and an electric actuator (specifically, a stepping motor) that acts as a drive unit that displaces the valve element. The operation of the bypass side expansion valve 14 is controlled by control pulses output from the control device 70.

[0047] The bypass expansion valve 14 has a full-open function that functions simply as a refrigerant passage without exerting any refrigerant pressure reduction or flow rate adjustment functions by fully opening the throttle valve 14. Furthermore, the bypass expansion valve 14 has a full-close function that closes the refrigerant passage by fully closing the throttle valve 14.

[0048] As described above, one outlet of the branch portion 12a is connected to the interior condenser 16. The interior condenser 16 is a heat-dissipating heat exchanger that exchanges heat between the high-pressure refrigerant discharged from the compressor 11 and the blown air supplied into the vehicle cabin, thereby dissipating heat contained in the high-pressure refrigerant to the blown air. The interior condenser 16 constitutes the heating portion 15 that uses the refrigerant discharged from the compressor 11 as a heat source to heat the blown air, which is an object to be heated.

[0049] A receiver 18 is connected to the outlet side of the indoor condenser 16. The receiver 18 is a gas-liquid separation unit that separates the refrigerant flowing out from the condenser (i.e., the indoor condenser 16) in the heat pump cycle 10 into gas and liquid phases and causes the liquid phase refrigerant to flow downstream, and also stores excess refrigerant from the cycle.

[0050] A low-temperature side expansion valve 19 is connected to the outlet side of the receiver 18. The low-temperature side expansion valve 19 is a pressure reducing unit that reduces the pressure of the refrigerant flowing into a refrigerant passage 21a of a chiller 21 that constitutes the heat absorption unit 20 when the refrigerant absorbs heat in the heat absorption unit 20. In other words, the low-temperature side expansion valve 19 is a chiller-side flow rate adjusting unit that adjusts the flow rate (mass flow rate) of the refrigerant flowing into the chiller 21.

[0051] The low-temperature side expansion valve 19 is configured as an electric variable throttle mechanism having a valve body and an electric actuator, similar to the bypass side expansion valve 14. The operation of the low-temperature side expansion valve 19 is controlled by control pulses output from the control device 70. Similarly to the bypass side expansion valve 14, the low-temperature side expansion valve 19 has a fully open function and a fully closed function.

[0052] A chiller 21 constituting a heat absorption unit 20 is connected to the outlet side of the low-temperature side expansion valve 19. The heat absorption unit 20 is a part where heat is absorbed from the low-pressure refrigerant decompressed by the low-temperature side expansion valve 19, and in the first embodiment, is constituted by a heat medium circuit 30 and the chiller 21.

[0053] The chiller 21 has a refrigerant passage 21a through which the low-pressure refrigerant decompressed by the low-temperature side expansion valve 19 flows, and a heat medium passage 21b through which the heat medium circulating in the heat medium circuit 30 flows. The chiller 21 is a low-temperature side heat medium heat exchanger that exchanges heat between the low-pressure refrigerant flowing in the refrigerant passage 21a and the heat medium flowing in the heat medium passage 21b. The chiller 21 cools the heat medium by evaporating the low-pressure refrigerant and exerting a heat absorption effect.

[0054] 1 , a three-way joint-shaped junction 12b is connected to the outlet side of a refrigerant passage 21a in the chiller 21. As described above, the bypass passage 13 and the bypass-side expansion valve 14 are connected to one inlet of the junction 12b. The outlet side of the refrigerant passage 21a of the chiller 21 is connected to the other inlet of the junction 12b.

[0055] The outlet side of the confluence part 12b is connected to the suction side of the compressor 11. Therefore, the confluence part 12b can merge the flow of refrigerant flowing out from the refrigerant passage 21a of the chiller 21 and the flow of refrigerant that has flowed through the bypass passage 13, and guide the merged flow to the suction side of the compressor 11.

[0056] Next, the heat medium circuit 30 of the vehicle air conditioner 1 according to the first embodiment will be described with reference to the drawings. The heat medium circuit 30 is a circuit for circulating a heat medium. In this embodiment, an ethylene glycol aqueous solution is used as the heat medium.

[0057] 1 , the heat medium circuit 30 according to the first embodiment is configured to be able to exchange heat with the low-pressure refrigerant of the heat pump cycle 10 in the chiller 21, and therefore can be referred to as a low-temperature side circuit 31. In addition to the heat medium passage 21b of the chiller 21, the low-temperature side circuit 31 also includes a low-temperature side pump 32, an outside-air heat exchanger 33, a heat medium three-way valve 34, and a bypass connection part 35.

[0058] The low-temperature side pump 32 is a heat medium pumping unit that sucks in the heat medium flowing out from the heat medium three-way valve 34 and pumps it to the outside air heat exchanger 33. The low-temperature side pump 32 is an electric water pump whose rotation speed (i.e., pumping capacity) is controlled by a control voltage output from the control device 70. Therefore, in the first embodiment, by driving the low-temperature side pump 32, it is possible to circulate the heat medium within the low-temperature side circuit 31.

[0059] An outside air heat exchanger 33 is connected to the discharge port side of the low-temperature side pump 32. The outside air heat exchanger 33 is disposed outside the vehicle compartment and exchanges heat between the heat medium cooled by the chiller 21 and circulating through the low-temperature side circuit 31 and the outdoor air outside the vehicle compartment. The outside air heat exchanger 33 constitutes a part of a heat absorption unit for absorbing heat from the outdoor air into the low-pressure refrigerant via the heat medium.

[0060] A heat medium three-way valve 34 is connected to the heat medium outlet side of the outside air heat exchanger 33. The heat medium three-way valve 34 is an electric three-way flow control valve having three inlet and outlet ports, and is configured to be able to continuously adjust the passage area ratio of each outlet port. The operation of the heat medium three-way valve 34 is controlled by a control signal output from the control device 70.

[0061] As described above, one of the inlet / outlet ports of the heat medium three-way valve 34 is connected to the heat medium outlet side of the outside air heat exchanger 33, and the other of the inlet / outlet ports of the heat medium three-way valve 34 is connected to one of the inlet / outlet ports of the heat medium passage 21b of the chiller 21. The other of the inlet / outlet ports of the heat medium three-way valve 34 is connected to the heat medium bypass flow path 36.

[0062] 1 , a bypass connection part 35 is connected to the other side of the inlet / outlet of the heat medium passage 21b of the chiller 21. The bypass connection part 35 is formed as a three-way joint having three inlet / outlets, and as described above, one of the inlet / outlets of the bypass connection part 35 is connected to the other side of the inlet / outlet of the heat medium passage 21b of the chiller 21.

[0063] The other inlet / outlet of the bypass connection portion 35 is connected to a heat medium bypass flow path 36, and the other inlet / outlet of the heat medium bypass flow path 36 is connected to the suction port side of the low-temperature side pump 32.

[0064] Therefore, according to the low-temperature side circuit 31 of the first embodiment, the circulation path of the heat medium via the chiller 21 and the outdoor air heat exchanger 33 can be switched by controlling the operation of the low-temperature side pump 32 and the heat medium three-way valve 34.

[0065] Next, the configuration of the interior air conditioning unit 60 that constitutes the vehicle air conditioner 1 will be described with reference to Fig. 2. The interior air conditioning unit 60 is a unit in the vehicle air conditioner 1 that blows out the blown air, the temperature of which has been adjusted by the heat pump cycle 10, to an appropriate location within the vehicle cabin. The interior air conditioning unit 60 is disposed inside the instrument panel at the front end of the vehicle cabin.

[0066] The interior air conditioning unit 60 according to the first embodiment is configured by accommodating an interior blower 62, a cooler core 33a, an interior condenser 16, etc. in an air passage formed inside an air conditioning case 61 that forms the outer shell of the unit. The air conditioning case 61 forms an air passage for ventilation air to be blown into the vehicle cabin. The air conditioning case 61 is molded from a resin (specifically, polypropylene) that has a certain degree of elasticity and excellent strength.

[0067] 2, an inside / outside air switching device 63 is disposed on the most upstream side of the blown air flow of the air conditioning case 61. The inside / outside air switching device 63 switches between introducing inside air (air inside the vehicle cabin) and outside air (air outside the vehicle cabin) into the air conditioning case 61.

[0068] The inside / outside air switching device 63 continuously adjusts the opening areas of the inside air inlet, which introduces inside air, and the outside air inlet, which introduces outside air, into the air-conditioning case 61, using an inside / outside air switching door, thereby changing the ratio of the amount of inside air introduced to the amount of outside air introduced. The inside / outside air switching door is driven by an electric actuator for the inside / outside air switching door. The operation of this electric actuator is controlled by a control signal output from the control device 70.

[0069] An interior blower 62 is disposed downstream of the inside / outside air switching device 63 in the flow of blown air. The interior blower 62 is configured as an electric blower that drives a centrifugal multi-blade fan with an electric motor. The interior blower 62 blows air drawn in through the inside / outside air switching device 63 toward the vehicle cabin. The rotation speed (i.e., blowing capacity) of the interior blower 62 is controlled by a control voltage output from the control device 70. The interior blower 62 can adjust the volume of the blown air, the temperature of which is to be adjusted, and thus corresponds to an example of a supply adjustment unit.

[0070] In the first embodiment, the cooler core 33a and the indoor condenser 16 are arranged in this order with respect to the flow of the blown air downstream of the indoor blower 62. The cooler core 33a constitutes a cooling heat exchanger that cools the blown air by exchanging heat between a medium (e.g., a heat medium or a refrigerant) cooled by a cold source (not shown) and the blown air flowing through the air conditioning case 61.

[0071] 2, the cooler core 33a is disposed in the air conditioning case 61 of the interior air conditioning unit 60, upstream of the interior condenser 16 in the flow of blown air. Therefore, in the interior air conditioning unit 60 of the vehicle air conditioner 1, at least a portion of the blown air that has passed through the cooler core 33a can be heated by the interior condenser 16.

[0072] A cool air bypass passage 65 is formed inside the air conditioning case 61. The cool air bypass passage 65 is an air passage that allows the blown air that has passed through the cooler core 33a to bypass the interior condenser 16 and flow downstream.

[0073] An air mix door 64 is disposed downstream of the cooler core 33a in the flow of blown air and upstream of the interior condenser 16. The air mix door 64 adjusts the ratio of the volume of blown air that passes through the interior condenser 16 and the volume of blown air that passes through the cooler core 33a to the volume of blown air that passes through the cold air bypass passage 65.

[0074] The air mix door 64 is driven by an electric actuator for driving the air mix door. The operation of this electric actuator is controlled by a control signal output from the control device 70. The air mix door 64 corresponds to an example of a supply adjustment unit, as it adjusts the supply amount of blown air, the temperature of which is adjusted in the indoor condenser 16, etc., by controlling its operation.

[0075] A mixing space is provided downstream of the interior condenser 16 in the flow of blown air. In the mixing space, the blown air heated by the interior condenser 16 and the blown air that has passed through the cold air bypass passage 65 and has not been heated by the interior condenser 16 are mixed.

[0076] Furthermore, openings for blowing the mixed air (conditioned air) into the vehicle cabin are arranged at the most downstream portion of the air flow of the air conditioning case 61. These openings include a face opening, a foot opening, and a defroster opening (none of which are shown).

[0077] The face opening is an opening for blowing conditioned air toward the upper bodies of occupants in the vehicle cabin, the foot opening is an opening for blowing conditioned air toward the feet of occupants, and the defroster opening is an opening for blowing conditioned air toward the inside surface of the window glass at the front of the vehicle.

[0078] These face opening holes, foot opening holes, and defroster opening holes are connected to face air outlets, foot air outlets, and defroster air outlets (none of which are shown) provided in the vehicle cabin via ducts that form air passages, respectively.

[0079] Therefore, the temperature of the conditioned air mixed in the mixing space is adjusted by the air mix door 64 adjusting the ratio of the air volume passing through the interior condenser 16 to the air volume passing through the cold air bypass passage 65. This also adjusts the temperature of the blown air (conditioned air) blown into the vehicle cabin from each air outlet.

[0080] A face door, a foot door, and a defroster door (none of which are shown) are disposed upstream of the face opening, foot opening, and defroster opening in the flow of blown air, respectively. The face door adjusts the opening area of ​​the face opening. The foot door adjusts the opening area of ​​the foot opening. The defroster door adjusts the opening area of ​​the defroster opening.

[0081] The face door, foot door, and defroster door constitute an air outlet mode switching device that switches the air outlet from which conditioned air is blown out. The face door, foot door, and defroster door are connected to an electric actuator for driving the air outlet mode doors via a link mechanism or the like, and are rotated in conjunction with each other. The operation of this electric actuator is controlled by a control signal output from the control device 70.

[0082] Next, an overview of the control system of the vehicle air conditioner 1 will be explained using Figure 3. The control device 70 is composed of a well-known microcomputer including a CPU, ROM, RAM, etc., and its peripheral circuits. The control device 70 performs various calculations and processes based on an air conditioning control program stored in the ROM, and controls the operation of various controlled devices connected to the output side. The control device 70 corresponds to an example of a control unit.

[0083] In the first embodiment, the various controlled devices include a compressor 11, a bypass side expansion valve 14, a low-temperature side expansion valve 19, a low-temperature side pump 32, a heat medium three-way valve 34, an indoor blower 62, an inside / outside air switching device 63, an air mix door 64, etc.

[0084] 3, various control sensors are connected to the input side of the control device 70. The control sensors include an inside air temperature sensor 72a, an outside air temperature sensor 72b, and a solar radiation sensor 72c. Other control sensors include a high-pressure sensor 72d, a low-pressure sensor 72e, a first refrigerant temperature sensor 72f, and a second refrigerant temperature sensor 72g. Other control sensors include a low-temperature heat medium temperature sensor 73a and an air conditioning air temperature sensor 73b.

[0085] The inside air temperature sensor 72a is an inside air temperature detector that detects the inside air temperature Tr, which is the temperature inside the vehicle cabin. The outside air temperature sensor 72b is an outside air temperature detector that detects the outside air temperature Tam, which is the temperature outside the vehicle cabin. The solar radiation sensor 72c is an insolation amount detector that detects the amount of solar radiation As irradiating the vehicle cabin.

[0086] The high-pressure pressure sensor 72d is a high-pressure pressure detection unit that detects the high-pressure pressure Pd, which is the pressure of the high-pressure refrigerant discharged from the compressor 11. The low-pressure pressure sensor 72e is a low-pressure pressure detection unit that detects the suction pressure (low-pressure pressure Ps) of the suction refrigerant drawn into the compressor 11. The first refrigerant temperature sensor 72f is a high-pressure side temperature detection unit that detects the temperature of the high-pressure refrigerant in the heat pump cycle 10. The first refrigerant temperature sensor 72f is disposed, for example, on the outlet side of the indoor condenser 16. The second refrigerant temperature sensor 72g is a low-pressure side temperature detection unit that detects the temperature of the low-pressure refrigerant in the heat pump cycle 10. The second refrigerant temperature sensor 72g is disposed, for example, on the outlet side of the refrigerant passage 21a of the chiller 21.

[0087] The low-temperature side heat medium temperature sensor 73a is a temperature detection unit that detects the temperature of the heat medium circulating through the low-temperature side circuit 31 of the heat medium circuit 30. The low-temperature side heat medium temperature sensor 73a is disposed, for example, on the outlet side of the heat medium passage 21b of the chiller 21. The conditioned air temperature sensor 73b is an air conditioning air temperature detection unit that detects the temperature TAV of the air blown from the mixing space into the vehicle cabin.

[0088] Furthermore, an operation panel 71 disposed near the instrument panel at the front of the vehicle interior is connected to the input side of the control device 70. Operation signals are input to the control device 70 from various operation switches provided on this operation panel 71.

[0089] The various operation switches provided on the operation panel 71 specifically include an auto switch, an air conditioner switch, an air volume setting switch, a temperature setting switch, etc. The auto switch is an operation switch that sets or cancels automatic control operation of the heat pump cycle 10.

[0090] The air conditioner switch is an operation switch that requests cooling of the blown air by the cooler core 33a. The air volume setting switch is an operation switch that is operated to manually set the air volume of the interior blower 62. The temperature setting switch is an operation switch that sets a target temperature Tset in the vehicle cabin.

[0091] The control device 70 of this embodiment is an integrated unit that controls various control target devices connected to its output side. Therefore, the configuration (i.e., hardware and software) that controls the operation of each control target device constitutes a control unit that controls the operation of each control target device.

[0092] For example, the control device 70 includes a configuration that executes switching control to reduce the difference in heating capacity of the object to be heated (i.e., the blown air) when switching from the heat pump heating mode described below to the hot gas heating mode, and corresponds to the switching control execution unit 70a.

[0093] Furthermore, in the control device 70, the configuration that controls the limiting operation for limiting the amount of heat radiation in the heating unit 15 during switching control when switching from the heat pump heating mode to the hot gas heating mode corresponds to the limiting control unit 70b.

[0094] Furthermore, within the control device 70, the configuration that performs the heat absorption amount securing operation to secure the amount of heat absorption in the heat absorption section 20 during switching control when switching from heat pump heating mode to hot gas heating mode corresponds to the heat absorption amount securing control section 70c.

[0095] The operating modes of the vehicle air conditioner 1 for heating the blown air, which is the object to be heated, include a heat pump heating mode and a hot gas heating mode. First, the heat pump heating mode of the vehicle air conditioner 1 will be described with reference to FIG.

[0096] The heat pump heating mode according to the first embodiment is an operating mode in which heat absorbed from a heat sink (air outside the vehicle cabin) is pumped up via the low-temperature side circuit 31 and released into the blown air by the interior condenser 16 that constitutes the heating unit 15. Therefore, the heat pump heating mode corresponds to an example of the first heating mode, since it pumps up heat absorbed from a heat sink to heat the blown air.

[0097] In the heat pump heating mode in the first embodiment, the control device 70 fully closes the bypass expansion valve 14 and throttles the low-temperature side expansion valve 19. Therefore, in the heat pump cycle 10 in the heat pump heating mode, the refrigerant is switched to a refrigerant circuit in which the refrigerant flows and circulates through the compressor 11, the branching portion 12a, the indoor condenser 16, the receiver 18, the low-temperature side expansion valve 19, the chiller 21, the junction portion 12b, and the compressor 11 in this order.

[0098] The control device 70 controls the refrigerant discharge capacity of the compressor 11 so that the high-pressure pressure Pd detected by the high-pressure pressure sensor 72d approaches the target high-pressure PDO. The target high-pressure PDO is determined based on the target blow-off temperature TAO by referring to a control map pre-stored in the control device 70. The control map determines the target high-pressure PDO to increase as the target blow-off temperature TAO increases.

[0099] In addition, the control device 70 controls the throttle opening of the low-temperature side expansion valve 19 so that the superheat SHC of the refrigerant at the outlet side of the refrigerant passage 21a in the chiller 21 approaches the reference superheat KSH within a range in which the refrigerant evaporation temperature in the chiller 21 is lower than the outside air temperature Tam.

[0100] With regard to the heat transfer medium circuit 30, the control device 70 determines the pumping capacity of the low-temperature side pump 32 and the opening area ratio of the three inlets and outlets of the heat transfer medium three-way valve 34 so as to ensure the amount of heat absorption required to achieve the target blowing temperature.

[0101] Then, for the indoor air conditioning unit 60, the control device 70 determines and controls the blowing capacity of the indoor blower 62, the indoor / outdoor air ratio in the indoor / outdoor air switching device 63, and the ratio of the air mix door 64 in accordance with the operating conditions specified for the heat pump heating mode.

[0102] Therefore, in the heat pump cycle 10 in the heat pump heating mode, the state of the refrigerant changes as shown in the Mollier diagram of Fig. 4. That is, the refrigerant discharged from the compressor 11 (point A1 in Fig. 4) flows into the interior condenser 16 via the branch portion 12a. The refrigerant that flows into the interior condenser 16 radiates heat to the ventilation air, which is the object to be heated, and condenses inside the interior air conditioning unit 60 (from point A1 to point A2 in Fig. 4). This heats the ventilation air, which is the object to be heated, and heating of the vehicle cabin is achieved.

[0103] The refrigerant flowing out from the indoor condenser 16 flows into the receiver 18 and is separated into gas and liquid. The liquid-phase refrigerant flowing out from the receiver 18 flows into the low-temperature side expansion valve 19 and is decompressed (from point A2 to point A3 in FIG. 4). The refrigerant decompressed by the low-temperature side expansion valve 19 flows into the chiller 21 constituting the heat absorption section 20. The refrigerant flowing into the refrigerant passage 21a of the chiller 21 absorbs heat from the heat medium flowing through the heat medium passage 21b and evaporates (from point A3 to point A4 in FIG. 4). The refrigerant flowing out from the refrigerant passage 21a of the chiller 21 is drawn into the compressor 11 and compressed again (from point A4 to point A1 in FIG. 4).

[0104] That is, in the heat pump cycle 10 in the heat pump heating mode, a vapor compression refrigeration cycle is configured in which the indoor condenser 16 functions as a condenser and the chiller 21 functions as an evaporator.

[0105] Next, the hot gas heating mode of the vehicle air conditioner 1 will be described with reference to Fig. 5. In the hot gas heating mode according to the first embodiment, a portion of the high-pressure refrigerant discharged from the compressor 11 is introduced into the low-pressure side via the bypass passage 13, thereby utilizing the workload of the compressor 11 to improve the heating capacity of the object to be heated. The hot gas heating mode corresponds to an example of a second heating mode.

[0106] Furthermore, in the hot gas heating mode, the heat source (i.e., the low-temperature side circuit 31 and the outdoor air) is not used, and the object to be heated is heated using the workload of the compressor 11. Therefore, even if the amount of heat absorption from the heat source cannot be secured, the heating capacity can be improved.

[0107] In the heat pump cycle 10 in the hot gas heating mode according to the first embodiment, the control device 70 throttles the bypass expansion valve 14 and throttles the low-temperature expansion valve 19. Therefore, in the hot gas heating mode, a portion of the refrigerant discharged from the compressor 11 circulates by flowing through the compressor 11, branching section 12a, indoor condenser 16, receiver 18, low-temperature expansion valve 19, chiller 21, junction 12b, and compressor 11 in this order. At the same time, another portion of the refrigerant discharged from the compressor 11 circulates by flowing through the compressor 11, branching section 12a, bypass passage 13, bypass expansion valve 14, junction 12b, and compressor 11 in this order. That is, in the hot gas heating mode, a refrigerant circuit is switched to one in which the refrigerant circulates via both the indoor condenser 16 and the bypass passage 13.

[0108] The control device 70 controls the refrigerant discharge capacity of the compressor 11 so that the chiller-side refrigerant pressure Pc approaches a predetermined target low pressure. Controlling the chiller-side refrigerant pressure Pc, which corresponds to the suction refrigerant pressure (low pressure Ps), so that it approaches a constant pressure is effective for stabilizing the discharge flow rate Gr (mass flow rate) of the compressor 11.

[0109] More specifically, by setting the low-pressure pressure Ps to a constant pressure of saturated gas-phase refrigerant, the density of the suctioned refrigerant becomes constant. Therefore, by controlling the low-pressure pressure Ps to approach a constant pressure, it is easy to stabilize the discharge flow rate Gr of the compressor 11 at the same rotation speed.

[0110] The controller 70 also controls the throttle opening of the bypass side expansion valve 14 so that the discharge refrigerant pressure (high-pressure pressure Pd) approaches the target high-pressure PDO, and controls the throttle opening of the low-temperature side expansion valve 19 so that the superheat degree SH of the suction refrigerant approaches the reference superheat degree KSH.

[0111] In the heat medium circuit 30 in the hot gas heating mode, the control device 70 stops the low-temperature side pump 32. In the indoor air conditioning unit 60 in the hot gas heating mode, the control device 70 controls the operation of the indoor blower 62, the inside / outside air switching device 63, and the air mix door 64. In the hot gas heating mode, the opening degree of the air mix door 64 is often controlled so that almost the entire volume of the air blown from the indoor blower 62 passes through the indoor condenser 16.

[0112] Therefore, in the heat pump cycle 10 in the hot gas heating mode according to the first embodiment, the state of the refrigerant changes as shown in the Mollier diagram in FIG.

[0113] First, the flow of refrigerant discharged from compressor 11 (point B1 in FIG. 5) is branched at branching portion 12a. One of the refrigerant branches at branching portion 12a flows into interior condenser 16, which constitutes heating portion 15, and dissipates heat to the ventilation air in interior air-conditioning unit 60 (from point B1 to point B2 in FIG. 5). This heats the ventilation air, which is the object to be heated, and realizes heating of the vehicle cabin.

[0114] The refrigerant flowing out from the indoor condenser 16 flows through the receiver 18 into the low-temperature side expansion valve 19 and is decompressed (from point B2 to point B3 in FIG. 5 ). The refrigerant decompressed by the low-temperature side expansion valve 19 flows into the chiller 21 that constitutes the heat absorption unit 20. In the hot gas heating mode, the low-temperature side pump 32 is stopped, so there is no heat exchange between the refrigerant and the heat medium of the low-temperature side circuit 31 in the chiller 21. The refrigerant flowing out from the chiller 21 flows into the other inlet of the junction 12b.

[0115] The other refrigerant branched at branching portion 12a flows into bypass passage 13. The refrigerant flowing into bypass passage 13 is decompressed by bypass-side expansion valve 14 (from point B1 to point B5 in FIG. 5 ). The refrigerant decompressed by bypass-side expansion valve 14 flows into one inlet of junction portion 12b. The refrigerant flowing out of chiller 21 and the refrigerant flowing out of bypass-side expansion valve 14 are joined and mixed at junction portion 12b, which has a three-way joint shape (point B5 in FIG. 5 ), and are then drawn into compressor 11.

[0116] In the heat pump cycle 10 in the hot gas heating mode, the refrigerant with low enthalpy flowing out from the chiller 21 (point B3 in FIG. 5 ) and the refrigerant with high enthalpy flowing out from the bypass passage 13 (point B4 in FIG. 5 ) are mixed at the junction 12b. That is, in the heat pump cycle 10 in the hot gas heating mode, the refrigerants with different enthalpies are mixed and drawn into the compressor 11.

[0117] The hot gas heating mode is an operating mode that is executed when the amount of heat absorbed by the heat absorption unit 20 is low, such as when the outside air temperature Tam is extremely low. For this reason, when the refrigerant flowing out of the indoor condenser 16 flows through the heat absorption unit 20, there is a possibility that the heat contained in the refrigerant will be radiated to the outside. If the heat contained in the refrigerant is radiated to the outside, the amount of heat radiated by the refrigerant to the blown air in the indoor condenser 16 will decrease, and the heating capacity of the blown air will decrease.

[0118] In contrast, in the hot gas heating mode of this embodiment, the circulation of the heat medium that is the target of heat exchange with the refrigerant flowing out from the bypass passage 13 is stopped, so the heat contained in the refrigerant discharged from the compressor 11 can be maintained as much as possible.

[0119] Furthermore, in the hot gas heating mode, the throttle opening of low-temperature side expansion valve 19 is controlled so that the superheat degree SH of the suction refrigerant approaches the reference superheat degree KSH. This allows the suction refrigerant (point B5 in FIG. 5) to be in a gas-phase refrigerant state having a degree of superheat, even if the refrigerant discharge capacity of compressor 11 is increased to increase the amount of heat radiated from the discharged refrigerant to the blown air in indoor condenser 16.

[0120] Therefore, in the hot gas heating mode, even if the amount of heat absorbed from the heat absorption source is small, the heat generated by the work of the compressor 11 can be effectively used to heat the blown air, thereby realizing heating of the vehicle interior.

[0121] Here, in the heat pump heating mode of the vehicle air conditioner 1, as described above, the heat absorbed by the heat absorption unit 20 is pumped up and used to heat the object to be heated (blowing air) in the heating unit 15. Therefore, the heating capacity in the heat pump heating mode has a strong correlation with the amount of heat absorbed by the heat absorption unit 20, and the greater the amount of heat absorbed, the greater the heating capacity.

[0122] The amount of heat absorbed in the heat absorption unit 20 is affected by the temperature of the heat absorption object and the temperature or pressure of the low-pressure refrigerant in the heat pump cycle 10. In other words, to ensure a sufficient amount of heat absorption in the heat absorption unit 20, it is necessary to adjust the temperature of the low-pressure refrigerant in the heat pump cycle 10 to be lower than the temperature of the heat absorption object in the heat absorption unit 20 (for example, the heat medium or air).

[0123] Furthermore, since the heating capacity in the heat pump heating mode is strongly affected by the amount of heat absorbed by the heat absorption unit 20, it is conceivable that the required heating capacity for the heating object may not be exhibited depending on the state of the heat absorption unit 20. For example, if the heat absorption unit 20 is configured to absorb heat from the air, and the air temperature is too low, a sufficient amount of heat absorption may not be secured, resulting in insufficient heating capacity in the heat pump heating mode.

[0124] In this regard, in the hot gas heating mode, the heating capacity is determined by the workload of the compressor 11, so the heating capacity of the object to be heated can be increased without being affected by the amount of heat absorbed in the heat absorption section 20. Here, the workload of the compressor 11 is proportional to the flow rate of the refrigerant circulating through the compressor 11, and the flow rate of the refrigerant circulating through the compressor 11 is proportional to the density of the refrigerant sucked into the compressor 11 (suction density).

[0125] Therefore, in order to increase the heating capacity of the object to be heated in the hot gas heating mode, it is necessary to increase the suction density of the refrigerant in the compressor 11, in other words, it is necessary to increase the suction pressure of the refrigerant in the compressor 11.

[0126] As described above, the heating capacity of the object to be heated in the heat pump heating mode can be increased as the low pressure of the refrigerant in the heat pump cycle 10 is lower. On the other hand, the heating capacity of the object to be heated in the hot gas heating mode can be increased as the low pressure of the refrigerant in the heat pump cycle 10 is higher.

[0127] That is, the heat pump heating mode and the hot gas heating mode have contradictory characteristics in the relationship between the heating capacity of the object to be heated and the low pressure of the refrigerant in the heat pump cycle 10 .

[0128] Therefore, when switching from heat pump heating mode to hot gas heating mode, fluctuations in heating capacity may occur due to the conflicting characteristics of the relationship between the heating capacity of the object to be heated and the low pressure of the refrigerant in the heat pump cycle 10.

[0129] Specifically, when switching from heat pump heating mode to hot gas heating mode, it is thought that the low pressure of the refrigerant in the heat pump cycle 10 is lowered in order to exert greater heating capacity in the heat pump heating mode.

[0130] When the system is switched to the hot gas heating mode while the low-pressure refrigerant in the heat pump cycle 10 is low, the suction density of the refrigerant in the compressor 11 is low, resulting in a reduced workload for the compressor 11. In other words, when the system is switched to the hot gas heating mode while the low-pressure refrigerant is low, the heating capacity required for the hot gas heating mode cannot be secured, and the same heating capacity as in the heat pump heating mode before the switch cannot be guaranteed. This reduces the heating capacity of the blown air, which in turn reduces the temperature of the conditioned air blown into the vehicle cabin, potentially reducing the comfort of the passengers inside the vehicle cabin.

[0131] Thereafter, when the mode is switched to the hot gas heating mode, in order to ensure the necessary heating capacity, the low-pressure refrigerant in the heat pump cycle 10 is increased. By increasing the low-pressure refrigerant in the heat pump cycle 10, the heating capacity of the object to be heated is increased, and the blowing temperature of the air-conditioned air can be raised to the state before the mode was switched.

[0132] However, between the time when the heat pump heating mode is switched to the hot gas heating mode and the time when the heating capacity in the hot gas heating mode is increased to the state before the switch, time is required to increase the low-pressure in the heat pump cycle 10. As a result, when the operating mode is switched, the outlet temperature of the conditioned air supplied to the vehicle cabin changes, resulting in a period of reduced comfort for the occupants.

[0133] The vehicle air conditioning system 1 according to the first embodiment performs switching control to suppress fluctuations in the heating capacity of the object to be heated due to differences in the operating modes when switching from the heat pump heating mode to the hot gas heating mode.

[0134] As described above, the heating capacity in the heat pump heating mode and the hot gas heating mode is affected by the low pressure of the refrigerant in the heat pump cycle 10. In order to suppress fluctuations in the heating capacity during mode switching and to make the fluctuations last for a shorter period of time, it is desirable to quickly achieve a state in which the low pressure required in the heat pump heating mode is low and the low pressure required in the hot gas heating mode is high.

[0135] In order to increase the low pressure of the refrigerant in the heat pump cycle 10, it is necessary to increase the heat quantity of the refrigerant. Therefore, as one of the operations in the switching control for increasing the low pressure of the heat pump cycle 10 and suppressing fluctuations in the heating capacity, an operation of suppressing the amount of heat radiation on the high pressure side of the heat pump cycle 10 can be considered.

[0136] As a result, by suppressing the amount of heat radiation on the high-pressure side of the heat pump cycle 10, the refrigerant discharged from the compressor 11 retains heat, making it possible to increase the low-pressure side of the heat pump cycle 10. This allows the low-pressure side of the heat pump cycle 10 to be quickly increased to a desired level, making it possible to quickly eliminate fluctuations in heating capacity caused by switching of the operation mode. Hereinafter, the operation of suppressing the amount of heat radiation on the high-pressure side of the heat pump cycle 10 during operation mode switching control is referred to as a limiting operation.

[0137] Furthermore, one possible operation in the switching control for increasing the low pressure of the heat pump cycle 10 and suppressing fluctuations in heating capacity is to maintain the amount of heat absorption on the low pressure side of the heat pump cycle 10 as much as possible.

[0138] As described above, in the heat pump heating mode before switching, the heat absorption unit 20 on the low-pressure side of the heat pump cycle 10 absorbs heat via the heat medium in the heat medium circuit 30. The amount of heat absorbed by the heat absorption unit 20 constitutes the amount of heat in the refrigerant flowing on the low-pressure side. In this state, for example, if the low-temperature side pump 32 is stopped to stop the heat absorption in the heat absorption unit 20, the amount of heat supplied from the heat absorption unit 20 to the refrigerant on the low-pressure side is immediately lost, and it is expected that the low-pressure pressure in the heat pump cycle 10 will temporarily drop.

[0139] Taking this into consideration, when switching from the heat pump heating mode to the hot gas heating mode, heat absorption in the heat absorption unit 20 continues from the heat pump heating mode. However, switching control when switching the operation mode is performed within a range that allows the amount of heat absorption in the heat absorption unit 20 to be maintained, thereby suppressing a drop in the low-pressure side of the heat pump cycle 10. Hereinafter, the operation for maintaining the amount of heat absorption on the low-pressure side of the heat pump cycle 10 as much as possible during switching control of the operation mode is referred to as heat absorption amount ensuring operation.

[0140] Next, switching control when switching from the heat pump heating mode to the hot gas heating mode in the vehicle air conditioner 1 according to the first embodiment will be described in detail with reference to FIG. 6, including the operation of each component.

[0141] 6, the automotive air conditioner 1 has been operating in the heat pump heating mode since time ta. As described above, in the automotive air conditioner 1 operating in the heat pump heating mode, the control device 70 controls the operation of the compressor 11, the bypass expansion valve 14, the low-temperature side expansion valve 19, the low-temperature side pump 32, the interior blower 62, the air mix door 64, etc.

[0142] As described above, in the heat pump heating mode, the throttle opening of bypass-side expansion valve 14 is controlled to be fully closed. In addition, the rotation speed of compressor 11, the throttle opening of low-temperature side expansion valve 19, the pumping capacity of low-temperature side pump 32, the blowing capacity of indoor blower 62, and the opening of air mix door 64 are controlled to satisfy the conditions defined for the heat pump heating mode described above.

[0143] At time tb, a decision is made to switch the operating mode from the heat pump heating mode to the hot gas heating mode, and switching control is initiated in the vehicle air conditioner 1. The switching control can be initiated, for example, when the amount of heat absorbed by the heat absorption unit 20 is insufficient for the required heating capacity, and the heat pump heating mode cannot meet the required heating capacity. The relationship between the required heating capacity and the amount of heat absorption is determined based on the relationship between the target blowout temperature of the conditioned air and the temperature of the heat absorption object (air) at the heat absorption unit 20.

[0144] The conditions for starting the switching control are not limited to the above example. For example, the switching from the heat pump heating mode to the hot gas heating mode may be determined based on the operation of the operation panel 71 by the occupant.

[0145] At time tb, when switching control from heat pump heating mode to hot gas heating mode begins, the operating modes of the rotation speed of the compressor 11, the throttling opening of the low-temperature side expansion valve 19, the pressure-feeding capacity of the low-temperature side pump 32, the blowing capacity of the indoor blower 62, and the opening of the air mix door 64 are controlled.

[0146] The rotation speed of compressor 11 is adjusted from the rotation speed in heat pump heating mode to a predetermined rotation speed determined by the switching control, and the throttle opening of low-temperature side expansion valve 19 is switched from a mode in which the throttle opening fluctuates in heat pump heating mode to a mode in which the throttle opening is maintained at the predetermined throttle opening determined by the switching control.

[0147] The throttle opening of the bypass side expansion valve 14 is controlled from the fully closed state (i.e., throttle opening=0) in the heat pump heating mode to maintain a predetermined throttle opening determined in the switching control.

[0148] As a result, during switching control, part of the refrigerant in the heat pump cycle 10 flows and circulates through the compressor 11, branch portion 12a, indoor condenser 16, receiver 18, low-temperature side expansion valve 19, chiller 21, and junction portion 12b in this order. At the same time, another part of the refrigerant discharged from the compressor 11 flows and circulates through the compressor 11, branch portion 12a, bypass passage 13, bypass side expansion valve 14, junction portion 12b, and compressor 11 in this order.

[0149] That is, under the switching control, the refrigerant circuit is switched to one in which a path in which the refrigerant circulates via the indoor condenser 16 and a path in which the refrigerant circulates via the bypass passage 13 coexist. At this time, in the heat pump cycle 10 under the switching control, the indoor condenser 16 functions as a radiator, and the chiller 21 functions as a heat absorber.

[0150] During switching control, the pumping rate of the low-temperature side pump 32 (i.e., the discharge rate of the heat medium) is controlled to maintain the pumping rate in the heat pump heating mode. As a result, during switching control, the heat absorption rate of the low-pressure refrigerant in the heat pump cycle 10 is maintained at the same level as in the heat pump heating mode. During switching control, the operation of maintaining the pumping rate of the low-temperature side pump 32 corresponds to an example of an operation of ensuring the heat absorption rate during switching control.

[0151] Furthermore, the airflow rate of the indoor fan 62 is controlled to a predetermined value for the switching control, and operates to maintain the predetermined value during the switching control. Because the airflow rate of the indoor fan 62 during the switching control is set lower than the airflow rate in the heat pump heating mode, after the elapse of time tb, the airflow rate of the indoor fan 62 is controlled to gradually decrease toward the predetermined value during the switching control.

[0152] That is, in the switching control, the supply amount of the object to be heated (blow air) supplied to the indoor condenser 16 constituting the heating unit 15 is limited by controlling the operation of the indoor blower 62. Therefore, in the switching control, the operation of limiting the blowing capacity of the indoor blower 62 to a value lower than that in the heat pump heating mode corresponds to an example of a limiting operation in the switching control.

[0153] The opening degree of the air mix door 64 is controlled to a predetermined value that is set so that the opening degree of the cool air bypass passage 65 is larger than in the heat pump heating mode. That is, during the switching operation, the air mix door 64 is controlled so that most of the blown air that has passed through the cooler core 33a flows bypassing the indoor condenser 16.

[0154] Here, if the supply amount of the object to be heated (blow air) supplied to the indoor condenser 16 is limited to a value lower than that in the heat pump heating mode, the amount of heat radiated from the high-pressure refrigerant in the heat pump cycle 10 in the heating unit 15 also decreases compared to that in the heat pump heating mode. Therefore, in the switching control, the operation of adjusting the opening degree of the air mix door 64 corresponds to an example of a limiting operation in the switching control.

[0155] In this way, when the operation control of each component related to the switching control is performed after the time tb has elapsed, the high pressure of the refrigerant in the heat pump cycle 10 decreases. In Fig. 6, the time point at which the various operations in the switching control are completed is indicated as time tc.

[0156] After time tc, while the switching control is continued, the above-mentioned limiting operation and heat absorption amount ensuring operation are also continued. In the switching control, a state in which the limiting operation and the heat absorption amount ensuring operation are performed in parallel is called a first state of the switching control.

[0157] Since the limiting operation limits the amount of heat dissipated from the high-pressure side of the refrigerant in the heat pump cycle 10, the value of the high-pressure refrigerant pressure increases over time from the start of the limiting operation. That is, the limiting operation in the switching control can improve the heating capacity of the heat pump cycle 10.

[0158] Furthermore, because the heat absorption amount ensuring operation ensures that the amount of heat absorption in the heat absorption unit 20 on the low-pressure side of the heat pump cycle 10 is approximately the same as that in heat pump heating operation, the low-pressure refrigerant pressure gradually increases as time passes from the start of the heat absorption amount ensuring operation. Similarly, the temperature of the low-pressure refrigerant flowing through the heat absorption unit 20 (i.e., the temperature of the low-pressure refrigerant flowing out from the refrigerant passage 21a of the chiller 21) also increases as time passes from time tc. In other words, the heat absorption amount ensuring operation in the switching control gradually increases the density of the refrigerant suctioned into the compressor 11, thereby increasing the workload of the compressor 11.

[0159] Furthermore, the rotation speed of the compressor 11, the throttle opening of the low-temperature side expansion valve 19, the throttle opening of the bypass side expansion valve 14, and the pumping volume of the low-temperature side pump 32 are controlled so as to maintain the predetermined values ​​set for the switching control.

[0160] As switching control continues, from time tc, the limiting operation and the heat absorption amount ensuring operation are performed, and the refrigerant temperature in the refrigerant passage 21a of the chiller 21 reaches a predetermined reference chiller-side temperature KTc. The reference chiller-side temperature KTc is determined based on the temperature of the heat medium flowing through the heat medium passage 21b of the chiller 21, and indicates that the amount of heat absorption in the chiller 21 is less than a predetermined amount. The refrigerant temperature in the refrigerant passage 21a of the chiller 21 being equal to or higher than the predetermined reference chiller-side temperature KTc is an example of a heat absorption stop condition.

[0161] The point in time td when the temperature of the low-pressure refrigerant in the refrigerant passage 21a of the chiller 21 reaches the reference chiller-side temperature KTc and the heat absorption stop condition is satisfied is referred to as time td. The point in time td indicates the point in time when the heat absorption amount in the heat absorption unit 20 can no longer be sufficiently secured. Therefore, even if the heat absorption amount securing operation is performed, it is difficult to use the heat absorption amount to raise the low-pressure refrigerant.

[0162] For this reason, after the time td has elapsed, the operation of the low-temperature side pump 32 is stopped, and the amount of heat medium pumped by the low-temperature side pump 32 is set to 0. As a result, the amount of heat absorbed by the chiller 21 constituting the heat absorption unit 20 becomes sufficiently small, and the heat absorption amount ensuring operation in the switching control is terminated.

[0163] 6, the heat absorption amount ensuring operation is terminated by stopping the operation of the low-temperature side pump 32, but the present invention is not limited to this. For example, as an example of an operation to reduce the amount of heat medium supplied to the chiller 21 in order to terminate the heat absorption amount ensuring operation, the heat medium circulation path in the low-temperature side circuit 31 may be switched to a path that does not pass through the heat medium passage 21b of the chiller 21. By controlling the operation of the heat medium three-way valve 34 to switch the heat medium circulation path as described above, it is possible to achieve the same effect as stopping the operation of the low-temperature side pump 32.

[0164] By stopping the heat absorption amount securing operation when the heat absorption stop condition is satisfied in this way, it is possible to suppress the waste of energy required for the heat absorption amount securing operation and realize energy-efficient switching control.

[0165] Even after the heat absorption amount securing operation is completed, the refrigerant circulation and the limiting operation in the heat pump cycle 10 under the switching control continue. This state is called the second state of the switching control. Because the limiting operation is continuously performed in the second state of the switching control, the high-pressure pressure, low-pressure pressure, and low-pressure-side refrigerant temperature of the refrigerant in the heat pump cycle 10 increase over time even after the time td and the end of the heat absorption amount securing operation.

[0166] As described above, the switching control is executed to suppress fluctuations in heating capacity when switching from the heat pump heating mode to the hot gas heating mode. As one of the methods for suppressing fluctuations in heating capacity, in the second state of the switching control, it is determined whether the high-pressure refrigerant in the heat pump cycle 10 has increased to a state where the heating capacity in the hot gas heating mode is equivalent to that in the heat pump heating mode.

[0167] Specifically, it is determined whether the high-pressure pressure of the refrigerant in the heat pump cycle 10 under switching control is higher than a predetermined reference high-pressure pressure KPd. If the high-pressure pressure in the heat pump cycle 10 under switching control is higher than the reference high-pressure pressure KPd, the hot gas heating mode can exhibit heating capacity equivalent to that of heat pump heating, thereby suppressing fluctuations in heating capacity.

[0168] Another method for suppressing fluctuations in heating capacity when switching to the hot gas heating mode is to increase the workload of the compressor 11 to a level equivalent to the heating capacity in the hot gas heating mode in the second state of the switching control. That is, in the second state of the switching control, it is determined whether the low-pressure pressure of the refrigerant in the heat pump cycle 10 has become higher than the reference low-pressure pressure KPs.

[0169] The reference low pressure KPs indicates the low pressure of the refrigerant in the heat pump cycle 10 and is set so that the workload of the compressor 11 in the hot gas heating mode is equivalent to the heating capacity in the heat pump heating mode. When the low pressure in the heat pump cycle 10 under switching control is higher than the reference low pressure KPs, the same heating capacity as that of heat pump heating can be exerted in the hot gas heating mode, thereby suppressing fluctuations in the heating capacity.

[0170] 6, when the switching control transitions to the second state after time td has elapsed, the high-pressure pressure and the low-pressure pressure in the heat pump cycle 10 gradually increase. The time te is the time when either the high-pressure pressure in the heat pump cycle 10 becomes equal to or greater than the reference high-pressure pressure KPd or the low-pressure pressure in the heat pump cycle 10 becomes equal to or greater than the reference low-pressure pressure KPs.

[0171] 6 illustrates an example in which the high-pressure pressure of the heat pump cycle 10 becomes equal to or greater than the reference high-pressure pressure KPd and the low-pressure pressure of the heat pump cycle 10 becomes equal to or greater than the reference low-pressure pressure KPs simultaneously. The illustration in FIG. 6 is merely an example, and the time te may be the time when either of the two conditions described above is met earlier. Furthermore, in order to reliably suppress fluctuations in heating capacity, the time te may be the time when both the high-pressure condition and the low-pressure condition are met.

[0172] When the high-pressure condition or the low-pressure condition of the refrigerant in the heat pump cycle 10 is satisfied and the time te has elapsed, the switching control is terminated and the mode is switched to hot gas heating mode. By terminating the limiting operation and switching to hot gas heating mode on the condition that the high-pressure condition of the refrigerant is satisfied, the hot gas heating mode is started with the heating capacity of the heat pump cycle 10 at a predetermined level (i.e., the level before the switching control). This makes it possible to start the hot gas heating mode with suppressed fluctuations in the heating capacity of the blown air, which is the object to be heated.

[0173] Furthermore, by terminating the limiting operation and switching to the hot gas heating mode, provided that the low-pressure condition of the refrigerant is satisfied, the hot gas heating mode is started when the workload of the compressor 11 reaches a predetermined level (i.e., the level before the switching control). Even in this case, the hot gas heating mode can be started while suppressing fluctuations in the heating capacity of the blown air, which is the object to be heated.

[0174] In the hot gas heating mode, as described above, the control device 70 controls the operation of the compressor 11, bypass side expansion valve 14, low temperature side expansion valve 19, low temperature side pump 32, indoor blower 62, air mix door 64, etc.

[0175] Specifically, in the hot gas heating mode, the throttle openings of the bypass-side expansion valve 14 and the low-temperature side expansion valve 19 are controlled to the throttle openings determined for the hot gas heating mode. The rotation speed of the compressor 11, the blowing capacity of the indoor blower 62, and the opening of the air mix door 64 are also controlled to satisfy the conditions determined for the hot gas heating mode. When transitioning to the hot gas heating mode following switching control, the pumping rate of the low-temperature side pump 32 remains at 0 because it remains stopped when transitioning from the second state of switching control.

[0176] In this way, when switching from the heat pump heating mode to the hot gas heating mode in the vehicle air conditioning system 1, the hot gas heating mode can be started with a sufficiently increased heating capacity of the heat pump cycle 10 by performing switching control and executing a limiting operation. This makes it possible to switch the operating mode while minimizing the difference in heating capacity between the heat pump heating mode and the hot gas heating mode due to the configuration of the refrigerant circuit.

[0177] 6 , as a limiting operation of the switching control, the operation of the indoor blower 62 is controlled to limit the amount of air supplied to the indoor condenser 16 that constitutes the heating unit 15. By limiting the amount of air sent by the indoor blower 62, the amount of heat radiation on the high-pressure side of the heat pump cycle 10 can be limited, and the heating capacity of the high-pressure side of the heat pump cycle 10 can be improved.

[0178] Furthermore, as a limiting operation of the switching control, the opening degree of the air mix door 64 is controlled to limit the amount of blown air supplied to the indoor condenser 16 that constitutes the heating unit 15. By operating the air mix door 64, it is possible to limit the amount of air supplied to the indoor condenser 16 from the perspective of the blown air path that is the object to be heated. Therefore, the limiting operation related to the operation control of the air mix door 64 can ensure sufficient heating capacity of the heat pump cycle 10 before switching to the hot gas heating mode.

[0179] 6, the switching control executes the limiting operation and the heat absorption amount ensuring operation in parallel. That is, by performing the limiting operation and the heat absorption amount ensuring operation in parallel, it is possible to utilize both the heating capacity of the high-pressure side of the heat pump cycle 10 and the workload of the compressor 11 due to the low-pressure side of the heat pump cycle 10. As a result, when switching from the heat pump heating mode to the hot gas heating mode, the period during which the heating capacity of the object to be heated fluctuates can be shortened and the fluctuations can be kept small.

[0180] In the switching control of the first embodiment, the heat absorption amount ensuring operation is performed in the same manner as in heat pump heating, by circulating a portion of the refrigerant discharged from the compressor 11 through the bypass passage 13 in parallel with the operation of absorbing heat from the heat medium into the low-pressure refrigerant in the chiller 21. This increases the low-pressure pressure of the heat pump cycle 10, improves the workload of the compressor 11, and realizes a circuit configuration that makes it easy to switch to hot gas heating mode.

[0181] As shown at time td in Fig. 6, the heat absorption amount ensuring operation in the switching control is terminated when the heat absorption stop condition is satisfied and the heat absorption amount becomes smaller than a predetermined reference value. That is, in the switching control, the heat absorption amount ensuring operation can be efficiently executed, and fluctuations in the heating capacity can be suppressed.

[0182] 6, when the heat absorption amount ensuring operation is being performed, if the heat absorption stop condition is met, the operation of the low-temperature side pump 32 is stopped and the amount of heat medium supplied to the chiller 21 of the heat absorption unit 20 is reduced to 0. By simple operation control, it is possible to achieve a reduction in the amount of heat absorption via the heat medium in the heat absorption unit 20.

[0183] As described above, the vehicle air conditioner 1 according to the first embodiment executes a limiting operation in the switching control when switching from the heat pump heating mode to the hot gas heating mode, limiting the amount of heat dissipation from the interior condenser 16 that constitutes the heating unit 15. By executing the limiting operation in the switching control, the heating capacity of the high-pressure side of the heat pump cycle 10 can be sufficiently increased, and fluctuations in heating capacity between the heat pump heating mode and the hot gas heating mode can be minimized.

[0184] 6 , as a limiting operation of the switching control, the operation of the indoor blower 62 is controlled to limit the amount of air supplied to the indoor condenser 16 that constitutes the heating unit 15. By limiting the amount of air sent by the indoor blower 62, the amount of heat radiation on the high-pressure side of the heat pump cycle 10 can be limited, and the heating capacity of the high-pressure side of the heat pump cycle 10 can be improved.

[0185] Furthermore, as a limiting operation in the switching control, the opening degree of the air mix door 64 is controlled to limit the amount of blown air supplied to the indoor condenser 16 that constitutes the heating unit 15. By operating the air mix door 64, it is possible to limit the amount of air supplied to the indoor condenser 16 from the perspective of the blown air path that is the object to be heated. Therefore, the limiting operation related to the operation control of the air mix door 64 makes it possible to ensure sufficient heating capacity of the heat pump cycle 10 before switching to the hot gas heating mode.

[0186] As shown from time tc to time te in Figure 6, the limiting operation in the switching control releases the limit on the heat radiation amount when the high-pressure pressure of the heat pump cycle 10 becomes equal to or higher than the reference high-pressure pressure KPd. The state in which the high-pressure pressure becomes equal to or higher than the reference high-pressure pressure indicates that the heating capacity of the heat pump cycle 10 has improved to a predetermined standard. Therefore, from the viewpoint of the heating capacity of the heat pump cycle 10, the limiting operation can be terminated when fluctuations in the heating capacity can be suppressed, and the system can be switched to the hot gas heating mode.

[0187] Furthermore, the limiting operation in the switching control releases the limit on the heat dissipation amount when the low-pressure pressure of the heat pump cycle 10 becomes equal to or greater than the reference low-pressure pressure KPs. The state in which the low-pressure pressure becomes equal to or greater than the reference low-pressure pressure KPs indicates that the workload of the compressor 11 has increased to a predetermined standard. Therefore, the limiting operation can be terminated and the system can be switched to the hot gas heating mode when fluctuations in the heating capacity can be suppressed from the perspective of the workload of the compressor 11.

[0188] As shown in Figure 6, in the switching control for switching from heat pump heating mode to hot gas heating mode, the limiting operation and the heat absorption amount ensuring operation are performed in parallel, and then the mode is switched to hot gas heating mode. The limiting operation improves the heating capacity of the heat pump cycle 10, while the heat absorption amount ensuring operation increases the workload of the compressor 11. Therefore, by performing the limiting operation and the heat absorption amount ensuring operation in parallel, the period required for the switching control can be shortened, and fluctuations in heating capacity can be suppressed in a short period of time.

[0189] Then, in the switching control when switching from the heat pump heating mode to the hot gas heating mode, a heat absorption amount ensuring operation is performed to ensure that the amount of heat absorption in the heat absorption unit 20 is the same as before the switching. By performing the heat absorption amount ensuring operation in the switching control, the density of the refrigerant drawn into the compressor 11 can be increased, and the workload of the compressor 11 can be sufficiently increased, and fluctuations in the heating capacity between the heat pump heating mode and the hot gas heating mode can be kept small.

[0190] As described above, in the heat pump cycle 10 when the heat absorption amount ensuring operation is being performed, a portion of the refrigerant discharged from the compressor 11 circulates via the chiller 21. At the same time, another portion of the refrigerant discharged from the compressor 11 circulates via the bypass passage 13. The heat absorption amount ensuring operation in the switching control is performed in a state where two refrigerant circulation paths similar to those in the hot gas heating mode coexist, so that the transition from the switching control to the hot gas heating mode can be performed in a short time with a simple operation.

[0191] 6 , the heat absorption amount ensuring operation in the switching control ends when the heat absorption stop condition is met, and heat absorption in the heat absorption unit 20 ends. The heat absorption stop condition indicates a situation in which the amount of heat absorbed in the heat absorption unit 20 has become small and there is no longer any need to continue the heat absorption amount ensuring operation. In other words, by ending the heat absorption amount ensuring operation when the heat absorption stop condition is met, the vehicle air conditioner 1 can efficiently execute the switching control and transition to the hot gas heating mode with reduced fluctuations in heating capacity.

[0192] When the heat absorption amount securing operation is terminated and heat absorption in the heat absorption unit 20 is suppressed, the pumping rate of the low-temperature side pump 32 is reduced to 0. In other words, heat absorption is suppressed by reducing the supply rate of the heat medium constituting the heat absorption object to the chiller 21 constituting the heat absorption unit 20. By adopting this configuration, heat absorption in the heat absorption unit 20 can be suppressed by simple control.

[0193] Second Embodiment Next, a second embodiment, which differs from the above-described embodiment, will be described with reference to Figures 7 to 9. Similar to the first embodiment, the heat pump cycle device according to the second embodiment is applied to a vehicle air conditioner 1 mounted on an electric vehicle. However, in the vehicle air conditioner 1 according to the second embodiment, the configuration of the heat absorption unit 20 is changed from that of the first embodiment, and the vehicle air conditioner 1 according to the second embodiment is configured as a vehicle heating device.

[0194] Other components of the vehicle air conditioner 1 according to the second embodiment (heat pump cycle 10, interior air conditioning unit 60, etc.) are the same as those of the above-described embodiment, and therefore will not be described again.

[0195] 7, unlike the first embodiment, the heat absorption section 20 of the vehicle air conditioner 1 according to the second embodiment is configured with an outside air heat absorber 22. Also, unlike the first embodiment, the heat medium circuit 30 and the components associated with the heat medium circuit 30 are eliminated in the second embodiment. That is, the low-temperature side pump 32, the outside air heat exchanger 33, the heat medium three-way valve 34, and the like, which were arranged in the low-temperature side circuit 31 of the heat medium circuit 30, are now arranged.

[0196] The heat pump cycle 10 according to the second embodiment has the same configuration as that of the first embodiment, except for the configuration of the heat absorption unit 20. Similar to the chiller 21 of the first embodiment, the outside air heat absorber 22 is disposed between the outlet side of the low-temperature side expansion valve 19 and the junction 12b. The outside air heat absorber 22 is a heat absorber that exchanges heat between the refrigerant flowing out from the low-temperature side expansion valve 19 and outside air present outside the passenger compartment of the electric vehicle, thereby absorbing heat contained in the outside air into the low-pressure refrigerant. That is, the object of heat absorption in the heat absorption unit 20 of the second embodiment is outside air.

[0197] The method of supplying outside air to the outside air heat sink 22 is not particularly limited. For example, the outside air may be supplied by operating an outside air fan (not shown), or a configuration may be adopted in which wind generated by the running of the electric vehicle is used.

[0198] A shutter device 23 is disposed upstream of the outside air flow relative to the outside-air heat sink 22. The shutter device 23 is configured by rotatably arranging multiple blades in an opening of a frame. The multiple blades rotate in unison by the operation of an electric actuator (not shown) to adjust the opening area of ​​the frame opening.

[0199] As a result, the shutter device 23 can adjust the flow rate of outside air supplied to the outside air heat sink 22, and can adjust the amount of heat absorption in the outside air heat sink 22. Therefore, the shutter device 23 corresponds to an example of a heat absorption amount adjustment unit.

[0200] The vehicle air conditioner 1 according to the second embodiment configured as described above can also achieve a heat pump heating mode and a hot gas heating mode. In the heat pump heating mode according to the second embodiment, the bypass expansion valve 14 is fully closed and the low-temperature expansion valve 19 is throttled. At this time, the shutter device 23 has an opening area sufficient to supply outside air to the outside-air heat sink 22.

[0201] By controlling the operation in this manner, the heat pump cycle 10 can absorb heat from the outside air using the outside air heat absorber 22 that constitutes the heat absorption unit 20, and can also pump up the absorbed heat and radiate it to the blown air using the indoor condenser 16 that constitutes the heating unit 15. As with the first embodiment, the heat pump heating mode according to the second embodiment corresponds to an example of the first heating mode.

[0202] In the hot gas heating mode according to the second embodiment, the bypass expansion valve 14 and the low-temperature expansion valve 19 are each throttled to a predetermined value to circulate the refrigerant in the heat pump cycle 10. At this time, the shutter device 23 is controlled to minimize the opening area, thereby minimizing the amount of outside air supplied to the outside-air heat absorber 22.

[0203] As a result, the heat pump cycle 10 in the hot gas heating mode according to the second embodiment has a refrigerant circuit in which a path in which the refrigerant circulates via the indoor condenser 16 and a path in which the refrigerant circulates via the bypass passage 13 coexist. That is, a portion of the refrigerant discharged from the compressor 11 circulates by flowing through the compressor 11, branching section 12a, indoor condenser 16, receiver 18, low-temperature side expansion valve 19, outdoor air heat absorber 22, junction section 12b, and compressor 11 in this order. At the same time, another portion of the refrigerant discharged from the compressor 11 circulates by flowing through the compressor 11, branching section 12a, bypass passage 13, bypass side expansion valve 14, junction section 12b, and compressor 11 in this order.

[0204] As described above, in the hot gas heating mode, refrigerants with different enthalpies, such as the low-enthalpy refrigerant flowing out from the outside air heat sink 22 and the high-enthalpy refrigerant flowing out from the bypass passage 13, are mixed and drawn into the compressor 11. Therefore, as in the first embodiment, in the hot gas heating mode, even if the amount of heat absorbed from the heat absorption source (outside air) is small, the heat generated by the work of the compressor 11 can be effectively used to heat the blown air, thereby realizing heating of the vehicle cabin. That is, the hot gas heating mode in the second embodiment also corresponds to an example of the second heating mode.

[0205] In the vehicle air conditioner 1 according to the second embodiment, it is also possible that the heating capacity may be insufficient while the heat pump heating mode is in operation. For example, if the outside air temperature is too low to meet the required heating capacity, the heat pump heating mode cannot cope with the situation, and it may be desirable to switch to the hot gas heating mode.

[0206] For this reason, also in the second embodiment, when switching from the heat pump heating mode to the hot gas heating mode, switching control is performed to suppress fluctuations in heating capacity.

[0207] When switching control is started in the vehicle air conditioning system 1 of the second embodiment, as in the first embodiment, the rotation speed of the compressor 11 is controlled to a predetermined rotation speed, and the throttle opening of the bypass side expansion valve 14 and the low-temperature side expansion valve 19 is controlled to a predetermined value.

[0208] Then, with the start of the switching control, the operation of the indoor blower 62 and the air mix door 64 is controlled, and the same limiting operation as in the first embodiment is executed. In the switching control of the second embodiment, as a heat absorption amount ensuring operation, the shutter device 23 is operated so as to make the opening area as large as possible in order to ensure the supply amount of outside air to the outside air heat sink 22.

[0209] As a result, the vehicle air conditioner 1 of the second embodiment achieves circulation of the refrigerant in the heat pump cycle 10 in the manner shown in Fig. 8. In this first state, the limiting operation limits the amount of heat dissipation in the heating unit 15, and the heat absorption amount ensuring operation ensures the amount of heat absorption in the outside-air heat absorber 22. As a result, from the perspectives of the high-pressure side and the low-pressure side of the heat pump cycle 10, the heating capacity after switching can be increased to be equivalent to that before switching, and fluctuations in the heating capacity can be suppressed.

[0210] When the switching control of the second embodiment shifts to the second state, the heat absorption amount securing operation performed in the first state is stopped, and only the limiting operation is performed. As in the first embodiment, the switching control shifts from the first state to the second state when the amount of heat absorption in the heat absorption unit 20 becomes low. Therefore, the timing of the shift is determined by the relationship between the temperature of the low-pressure refrigerant in the outside air heat sink 22 and the outside air temperature.

[0211] In the first state of the switching control according to the second embodiment, the amount of outside air supplied to the outside air heat absorber 22 is minimized by controlling the operation of the shutter device 23, and the heat absorption amount securing operation is terminated. As a result, the second state of the switching control according to the second embodiment is realized, as shown in Fig. 9. Note that even in the second state of the switching control, the refrigerant circulation and the limiting operation continue to be performed.

[0212] This reduces the energy consumption required to maintain the heat absorption capacity when the heat absorption capacity is reduced, while limiting the amount of heat dissipation, thereby increasing the heating capacity to a level similar to that before switching.

[0213] In other words, in the vehicle air conditioning system 1 according to the second embodiment, by executing switching control when switching from heat pump heating mode to hot gas heating mode, fluctuations in heating capacity that accompany switching of operating modes can be suppressed.

[0214] As described above, according to the vehicle air conditioning device 1 of the second embodiment, even if the configuration of the heat absorption section 20 is changed, the same effects as those of the above-mentioned embodiment can be obtained from the configuration and operation.

[0215] Third Embodiment Next, a third embodiment, which differs from the above-described embodiments, will be described with reference to Figures 10 to 12. In the vehicle air conditioner 1 according to the third embodiment, the configuration of the heat pump cycle 10 is changed from that of the heat pump cycle 10 in the above-described embodiments. Other components of the vehicle air conditioner 1 according to the third embodiment (such as the heat medium circuit 30 and the interior air conditioning unit 60) are the same as those in the above-described embodiments, and therefore will not be described again.

[0216] 10 , the vehicle air conditioner 1 according to the third embodiment is configured to include a heat pump cycle 10, a heat medium circuit 30, an interior air conditioning unit 60, and a control device 70. The configurations of the heat medium circuit 30, the interior air conditioning unit 60, the control device 70, etc. are the same as those of the first embodiment described above, and therefore will not be described again.

[0217] The heat pump cycle 10 according to the third embodiment includes a compressor 11, a bypass passage 13, a bypass-side expansion valve 14, an indoor condenser 16, a chiller 21, an outdoor air heat absorber 22, a first expansion valve 26, a second expansion valve 27, and an accumulator 28. That is, unlike the above-described embodiments, the heat pump cycle 10 according to the third embodiment is configured as a parallel circuit in which the chiller 21 and the outdoor air heat absorber 22 are connected in parallel on the low-pressure side, and is also configured as an accumulator cycle.

[0218] In the heat pump cycle 10 according to the third embodiment, a branch portion 12a is connected to the discharge port of the compressor 11. The configurations of the compressor 11 and the branch portion 12a are the same as those in the first embodiment, and therefore will not be described again.

[0219] One outlet of the branch portion 12a is connected to the inlet side of an indoor condenser 16 that constitutes the heating portion 15. The other outlet of the branch portion 12a is connected to a bypass passage 13 and a bypass-side expansion valve 14. The configuration and arrangement of the indoor condenser 16, and the configurations of the bypass passage 13 and the bypass-side expansion valve 14 are the same as those in the first embodiment described above.

[0220] A first connection part 24 in the form of a three-way joint is disposed on the outlet side of the indoor condenser 16. The first connection part 24 has one inlet and two outlets. A first expansion valve 26 and a refrigerant passage 21a of the chiller 21 are connected to one of the outlets of the first connection part 24. A second expansion valve 27 and an outdoor air heat sink 22 are connected to the other outlet of the first connection part 24.

[0221] Here, the first expansion valve 26 and the second expansion valve 27 are configured as electric expansion valves configured in the same manner as the above-mentioned low-temperature side expansion valve 19. Therefore, the first expansion valve 26 and the second expansion valve 27 have a valve body and an electric actuator, and their operation is controlled by a control pulse output from the control device 70. In addition, the first expansion valve 26 and the second expansion valve 27 have a fully open function and a fully closed function.

[0222] The chiller 21 constituting the heat absorption unit 20 is connected to the outlet side of the first expansion valve 26. As in the first embodiment, the chiller 21 has a refrigerant passage 21a and a heat medium passage 21b, and performs heat exchange between the refrigerant flowing through the refrigerant passage 21a and the heat medium flowing through the heat medium passage 21b. A second connection part 25 in the form of a four-way joint is connected to the outlet side of the refrigerant passage 21a of the chiller 21.

[0223] As in the first embodiment, the heat medium flowing through the heat medium passage 21b is the heat medium circulating through the low-temperature side circuit 31. The low-temperature side circuit 31 has a low-temperature side pump 32, an outside-air heat exchanger 33, a heat medium three-way valve 34, and a bypass connection part 35, and has the same configuration as in the first embodiment.

[0224] Therefore, according to the heat pump cycle 10 of the third embodiment, by using the chiller 21 as the heat absorption section 20, the heat contained in the outdoor air as the heat absorption source can be absorbed by the low-pressure refrigerant via the heat medium in the low-temperature side circuit 31.

[0225] An outside air heat sink 22 constituting the heat absorption unit 20 is connected to the outlet side of the second expansion valve 27. As in the second embodiment, the outside air heat sink 22 exchanges heat between the heat medium flowing through the outside air heat sink 22 and the outside air outside the vehicle cabin. A second connection part 25 in the form of a four-way joint is connected to the outlet side of the outside air heat sink 22.

[0226] Therefore, according to the heat pump cycle 10 of the third embodiment, by using the outside air heat absorber 22 as the heat absorption section 20, the heat of the outside air as a heat absorption source can be absorbed by the low-pressure refrigerant.

[0227] The second connection part 25 is formed as a four-way joint and has three inlets and one outlet. One of the inlets of the second connection part 25 is connected to the other end of the bypass passage 13 and the bypass-side expansion valve 14. The other inlet of the second connection part 25 is connected to the outlet side of the refrigerant passage 21a of the chiller 21. In addition, another inlet of the second connection part 25 is connected to the outlet side of the outdoor air heat sink 22.

[0228] The outlet side of the second connection part 25 is connected to the inlet side of the accumulator 28. In other words, the second connection part 25 constitutes the confluence part 12b that converges the refrigerant flow passing through the bypass passage 13, the refrigerant flow passing through the chiller 21, and the refrigerant flow passing through the outdoor air heat sink 22, and leads the refrigerant flow to the accumulator 28 side.

[0229] The outlet side of the second connection part 25 constituting the confluence part 12b is connected to the inlet side of the accumulator 28. The accumulator 28 is a low-pressure-side gas-liquid separator that separates the low-pressure refrigerant flowing out from the second connection part 25 into gas and liquid phases and stores the separated liquid-phase refrigerant as surplus refrigerant in the cycle. The gas-phase refrigerant outlet of the accumulator 28 is connected to the suction side of the compressor 11.

[0230] In the vehicle air conditioning system 1 according to the third embodiment configured as described above, the heat pump heating mode and the hot gas heating mode can also be executed as operating modes for heating the blown air, which is the object to be heated.

[0231] An example of the heat pump heating mode in the third embodiment will be described. In the heat pump heating mode in the third embodiment, the bypass expansion valve 14 and the first expansion valve 26 are fully closed, and the second expansion valve 27 is throttled to a predetermined value. At this time, the heat medium in the heat medium circuit 30 may be continued to circulate or may be stopped by controlling the operation of the low-temperature side pump 32.

[0232] As a result, in the heat pump cycle 10 in the heat pump heating mode of the third embodiment, the refrigerant flows and circulates through the compressor 11, the branching section 12a, the indoor condenser 16, the first connection section 24, the second expansion valve 27, the outdoor air heat absorber 22, the second connection section 25, and the accumulator 28 in that order.

[0233] That is, in the heat pump heating mode according to the third embodiment, a refrigerant circuit is configured in which the outdoor air heat sink 22 serves as a heat sink and the indoor condenser 16 serves as a heat sink, and heating operation is realized in which the outdoor air is used as a heat sink to heat the blown air. The heat pump heating mode according to the third embodiment corresponds to an example of the first heating mode.

[0234] As another example of the heat pump heating mode according to the third embodiment, a configuration can be adopted in which the bypass expansion valve 14 and the second expansion valve 27 are fully closed and the first expansion valve 26 is throttled to a predetermined value. In this case, the heat medium circuit 30 is controlled so that the heat medium circulates through the chiller 21 and the outdoor air heat exchanger 33. This configuration can realize the heat pump heating mode using outdoor air as a heat absorption source.

[0235] Next, the hot gas heating mode in the third embodiment will be described. In the hot gas heating mode in the third embodiment, the bypass expansion valve 14 and the first expansion valve 26 are controlled to be in a predetermined throttle state, and the second expansion valve 27 is controlled to be in a fully closed state. At this time, the heat medium circuit 30 is controlled to stop circulating the heat medium.

[0236] According to this configuration, in the hot gas heating mode of the third embodiment, the refrigerant circuit is switched to one in which a path in which the refrigerant circulates via the indoor condenser 16 and a path in which the refrigerant circulates via the bypass passage 13 coexist.

[0237] That is, a portion of the refrigerant discharged from the compressor 11 circulates by flowing in the following order: compressor 11, branch portion 12a, indoor condenser 16, first connection portion 24, first expansion valve 26, chiller 21, second connection portion 25, accumulator 28, and compressor 11. At the same time, another portion of the refrigerant discharged from the compressor 11 circulates by flowing in the following order: compressor 11, branch portion 12a, bypass passage 13, bypass-side expansion valve 14, second connection portion 25, accumulator 28, and compressor 11.

[0238] That is, in the hot gas heating mode according to the third embodiment, refrigerants with different enthalpies, such as a low-enthalpy refrigerant flowing out from the chiller 21 and a high-enthalpy refrigerant flowing out from the bypass passage 13, are mixed at the junction 12b. By mixing the refrigerants with different enthalpies and drawing them into the compressor 11, the workload of the compressor 11 can be increased, thereby improving the heating capacity for the object to be heated. The hot gas heating mode according to the third embodiment corresponds to an example of the second heating mode.

[0239] In the vehicle air conditioner 1 according to the third embodiment, it is also possible that the heating capacity may be insufficient while the heat pump heating mode is in operation. For example, if the outside air temperature is too low to meet the required heating capacity, the heat pump heating mode cannot cope with the situation, and it may be desirable to switch to the hot gas heating mode.

[0240] For this reason, also in the third embodiment, when switching from the heat pump heating mode to the hot gas heating mode, switching control is performed to suppress fluctuations in heating capacity.

[0241] In the vehicle air conditioner 1 according to the third embodiment, when switching control is initiated from the heat pump heating mode, the rotation speed of the compressor 11 is controlled to a predetermined rotation speed, as in the first embodiment. At this time, the throttle openings of the bypass expansion valve 14, the first expansion valve 26, and the second expansion valve 27 are controlled to their respective predetermined values. In addition, in the heat medium circuit 30, the operation of the low-temperature side pump 32 is stopped, thereby stopping the circulation of the heat medium through the chiller 21.

[0242] Then, with the start of the switching control, the operation of the indoor blower 62 and the air mix door 64 is controlled, and the same limiting operation as in the above-described embodiment is executed. In the switching control of the third embodiment, heat absorption from the outside air in the outside air heat sink 22 is executed as the heat absorption amount securing operation.

[0243] Furthermore, if a shutter device 23 is arranged for the outdoor air heat sink 22, as in the second embodiment, the shutter device 23 operates to make the opening area as large as possible in order to ensure the supply of outdoor air to the outdoor air heat sink 22.

[0244] 11 , the vehicle air conditioner 1 of the third embodiment achieves circulation of the refrigerant in the heat pump cycle 10. In the first state, the limiting operation limits the amount of heat dissipation in the heating unit 15, and the heat absorption amount ensuring operation ensures the amount of heat absorption in the outside-air heat absorber 22. As a result, in terms of the high-pressure side and the low-pressure side of the heat pump cycle 10, the heating capacity after the switching can be increased to be equivalent to that before the switching, and fluctuations in the heating capacity before and after the switching can be suppressed.

[0245] When the switching control of the third embodiment shifts to the second state, the heat absorption amount securing operation performed in the first state is stopped, and only the limiting operation is performed. As in the above-described embodiments, the switching control shifts from the first state to the second state when the amount of heat absorption in the heat absorption unit 20 becomes low. Therefore, the timing of the shift is determined by the relationship between the temperature of the low-pressure refrigerant in the outside air heat sink 22 and the outside air temperature.

[0246] The transition from the first state to the second state of the switching control according to the third embodiment (i.e., the end of the heat absorption amount securing operation) is achieved by changing the refrigerant flow path in the heat pump cycle 10. As shown in Fig. 11 , when the heat absorption amount securing operation is being performed, heat is absorbed from the outside air by a portion of the refrigerant that has passed through the first connection part 24 flowing through the second expansion valve 27 and the outside air heat absorber 22. When the heat absorption amount securing operation is to be ended, the refrigerant path is switched so that all of the refrigerant that has passed through the first connection part 24 passes through the first expansion valve 26 and the chiller 21.

[0247] Specifically, the state of the second expansion valve 27 is switched from the throttle state in the first state to the fully closed state, thereby stopping the supply of low-pressure refrigerant to the outdoor air heat absorber 22, and thus terminating the heat absorption amount securing operation. Note that even in the second state of the switching control, the refrigerant circulation and restriction operation continue to be performed.

[0248] As a result, the second state of the switching control according to the third embodiment is realized as shown in Fig. 12. Then, by limiting the amount of heat dissipation while suppressing the energy consumption of the heat absorption amount securing operation in a state where the amount of heat absorption has decreased, it is possible to increase the heating capacity to a state where the heating capacity can be maintained at the same level as before switching.

[0249] In other words, in the vehicle air conditioning system 1 according to the third embodiment, by executing switching control when switching from heat pump heating mode to hot gas heating mode, fluctuations in heating capacity associated with switching of operating modes can be suppressed.

[0250] As described above, according to the vehicle air conditioning system 1 of the third embodiment, even when a heat pump cycle 10 in which multiple heat absorbers constituting the heat absorption section 20 are arranged in parallel is adopted, it is possible to obtain the same effects as those of the above-described embodiment due to the configuration and operation.

[0251] 11 and 12 , in the vehicle air conditioner 1 according to the third embodiment, the heat absorption amount securing operation is terminated by switching the flow of refrigerant that has been used in the heat absorption amount securing operation from passing through the outside air heat absorber 22. Upon termination of the heat absorption amount securing operation, the flow of refrigerant that has passed through the outside air heat absorber 22 and absorbed heat in the heat absorption amount securing operation is switched to a flow of refrigerant that passes through the chiller 21 arranged in parallel, and the supply of low-pressure refrigerant to the outside air heat absorber 22 is stopped by bypassing the outside air heat absorber 22.

[0252] As described above, in the vehicle air conditioner 1 according to the third embodiment, the heat absorption unit 20 includes a plurality of heat absorbers (chiller 21, outdoor air heat absorber 22) arranged in parallel, and a heat absorption amount ensuring operation is performed using one of the heat absorbers. When the heat absorption amount ensuring operation is to be terminated, the refrigerant flow path on the low-pressure side is switched from a configuration that passes through one of the heat absorbers (outdoor air heat absorber 22) to a configuration that passes through the other heat absorber (chiller 21). This allows the refrigerant flow path to be switched to end the heat absorption amount ensuring operation, and the heat absorption associated with the heat absorption amount ensuring operation can be suppressed by simple control.

[0253] 13 to 16, a fourth embodiment, which differs from the above-described embodiments, will be described. In the fourth embodiment, a heat pump cycle device according to the present disclosure is applied to a vehicle air conditioner 1 for an electric vehicle, similar to the above-described embodiments. Similar to the above-described embodiments, the fourth embodiment is characterized in that fluctuations in heating capacity are suppressed when switching between multiple operating modes for heating an object to be heated.

[0254] In the fourth embodiment, an operation mode is also executed in which heat absorbed on the low-pressure side of the heat pump cycle 10 is pumped up and used to heat an object to be heated, and an operation mode is executed in which a portion of the refrigerant discharged from the compressor 11 is used to increase the workload of the compressor 11 and exert heating capacity. In other words, the operation modes in the fourth embodiment are different in detail, but are based on the same concept as the above-mentioned embodiments in the above points.

[0255] The vehicle air conditioner 1 according to the fourth embodiment is configured with a heat pump cycle 10, a heat medium circuit 30, an interior air conditioning unit 60, and a control device 70. In the fourth embodiment, the configurations of the heat pump cycle 10 and the heat medium circuit 30 are different from those of the above-described embodiments. In other words, the other configurations of the vehicle air conditioner 1 according to the fourth embodiment (such as the interior air conditioning unit 60 and the control device 70) are basically the same as those of the above-described embodiments, and therefore will not be described again.

[0256] 13 , the heat pump cycle 10 of the vehicle air conditioner 1 according to the fourth embodiment includes a compressor 11, a heat medium refrigerant heat exchanger 17, a low-temperature side expansion valve 19, and a chiller 21. The compressor 11 has the same configuration as in the above-described embodiments, and therefore, detailed description of the compressor 11 will be omitted.

[0257] The discharge port side of the compressor 11 is connected to the refrigerant inlet side of the heat medium refrigerant heat exchanger 17. The heat medium refrigerant heat exchanger 17 has a refrigerant passage 17a through which the high-pressure refrigerant discharged from the compressor 11 flows, and a heat medium passage 17b through which the heat medium circulating in the high-temperature side circuit 41 that constitutes the heat medium circuit 30 flows.

[0258] The heat medium-refrigerant heat exchanger 17 is a condenser that condenses the high-pressure refrigerant flowing through the refrigerant passage 17a by heat exchange with the heat medium flowing through the heat medium passage 17b. That is, the heat medium-refrigerant heat exchanger 17 transfers heat from the high-pressure refrigerant discharged from the compressor 11 to the heat medium circulating through the heat medium circuit 30, thereby heating the heat medium. Therefore, the heat medium-refrigerant heat exchanger 17 constitutes a part of the heating unit 15.

[0259] A low-temperature side expansion valve 19 is connected to the outlet side of the refrigerant passage 17a of the heat medium refrigerant heat exchanger 17. The low-temperature side expansion valve 19 has the same configuration as in the above-described embodiment and includes a valve body and an electric actuator. The operation of the low-temperature side expansion valve 19 is controlled by a control pulse output from the control device 70. The low-temperature side expansion valve 19 also has a fully open function and a fully closed function.

[0260] The outlet side of the low-temperature side expansion valve 19 is connected to the inlet side of a refrigerant passage 21a of the chiller 21. As in the above-described embodiment, the chiller 21 has a refrigerant passage 21a and a heat medium passage 21b, and performs heat exchange between the refrigerant flowing through the refrigerant passage 21a and the heat medium flowing through the heat medium passage 21b. Therefore, the chiller 21 constitutes a part of the heat absorption unit 20 that absorbs heat possessed by the heat medium flowing through the heat medium passage 21b into the low-pressure refrigerant flowing through the refrigerant passage 21a. The outlet side of the refrigerant passage 21a of the chiller 21 is connected to the suction side of the compressor 11.

[0261] The heat pump cycle 10 of the fourth embodiment configured in this manner pumps up heat absorbed in the heat absorption section 20 on the low-pressure side, dissipates the heat in the heating section 15 on the high-pressure side, and can be used to heat an object to be heated.

[0262] Next, a description will be given of the heat medium circuit 30 of the vehicle air conditioner 1 according to the fourth embodiment. As shown in Fig. 13 , the heat medium circuit 30 according to the fourth embodiment includes a low-temperature side circuit 31, a high-temperature side circuit 41, a heat medium connecting flow path 50, and a heat medium flow rate adjusting unit 55.

[0263] Similar to the first embodiment described above, the low-temperature side circuit 31 according to the fourth embodiment includes a heat medium passage 21b of a chiller 21, a low-temperature side pump 32, an outside-air heat exchanger 33, a heat medium three-way valve 34, a bypass connection part 35, and a heat medium bypass flow path 36. In the low-temperature side circuit 31, the positional relationship between the chiller 21 and the low-temperature side pump 32 to the heat medium bypass flow path 36 is similar to that in the above-described embodiments.

[0264] Therefore, in the low-temperature side circuit 31 of the fourth embodiment, the heat medium absorbed by the chiller 21 is circulated through the outdoor air heat exchanger 33, making it possible to absorb the heat contained in the outdoor air into the low-pressure refrigerant via the heat medium.

[0265] As shown in FIG. 13, the low-temperature side circuit 31 according to the fourth embodiment includes the above-mentioned chiller 21 and the low-temperature side pump 32 to the heat medium bypass flow path 36, as well as a low-temperature side flow rate adjustment unit 37 and a low-temperature side connection unit 38.

[0266] The low-temperature side flow rate adjustment unit 37 is an electric three-way flow rate adjustment valve having three inlets and three outlets, and is configured to be able to continuously adjust the passage area ratio of each outlet. The operation of the low-temperature side flow rate adjustment unit 37 is controlled by a control signal output from the control device 70.

[0267] The low-temperature side flow rate adjustment unit 37 is disposed between the outlet side of the heat medium passage 21b of the chiller 21 and the bypass connection unit 35. That is, one of the inlet and outlet ports of the low-temperature side flow rate adjustment unit 37 is connected to the outlet side of the heat medium passage 21b of the chiller 21, and the other of the inlet and outlet ports of the low-temperature side flow rate adjustment unit 37 is connected to one of the inlet and outlet ports of the bypass connection unit 35. A second connection flow path 52 is connected to the other inlet and outlet port of the low-temperature side flow rate adjustment unit 37. The second connection flow path 52 will be described later.

[0268] The low-temperature side connection part 38 is formed as a three-way joint having three inlet and outlets, and is disposed between the inlet side of the heat medium passage 21b of the chiller 21 and the heat medium three-way valve 34. Therefore, one of the inlet and outlet ports of the low-temperature side connection part 38 is connected to the inlet side of the heat medium passage 21b of the chiller 21, and the other of the inlet and outlet ports of the low-temperature side connection part 38 is connected to one of the outlet and inlet ports of the heat medium three-way valve 34. A first connection flow path 51 is connected to the other of the inlet and outlet ports of the low-temperature side connection part 38. The first connection flow path 51 will be described later.

[0269] According to the low-temperature side circuit 31 of the fourth embodiment configured as described above, a plurality of heat medium circulation modes can be realized by controlling the operation of the heat medium three-way valve 34, etc. In one of the heat medium circulation modes in the low-temperature side circuit 31, the heat medium is circulated by flowing through the low-temperature side pump 32, the outside-air heat exchanger 33, the heat medium three-way valve 34, the low-temperature side connection unit 38, the chiller 21, the low-temperature side flow rate adjustment unit 37, the bypass connection unit 35, and the low-temperature side pump 32 in this order.

[0270] As another circulation mode of the heat medium in the low-temperature side circuit 31, a mode can be realized in which the heat medium is circulated by flowing through the low-temperature side pump 32, the outside-air heat exchanger 33, the heat medium three-way valve 34, the heat medium bypass flow path 36, the bypass connection part 35, and the low-temperature side pump 32 in this order. Therefore, the low-temperature side circuit 31 according to the fourth embodiment corresponds to an example of a second circuit, and the outside-air heat exchanger 33 according to the fourth embodiment corresponds to an example of a heat medium heat absorber. The low-temperature side circuit 31, together with the chiller 21, constitutes the heat absorption part 20.

[0271] Next, the configuration of a high-temperature side circuit 41 of a heat medium circuit 30 according to a fourth embodiment will be described with reference to Fig. 13. The high-temperature side circuit 41 according to the fourth embodiment is a circuit in the heat medium circuit 30 in which the heat medium circulates via the heat medium-refrigerant heat exchanger 17 that constitutes the heating unit 15. In addition to the heat medium passage 17b of the heat medium-refrigerant heat exchanger 17, the high-temperature side circuit 41 according to the fourth embodiment also includes a high-temperature side pump 42, a heater core 43, a high-temperature side flow rate adjuster 44, and a high-temperature side connection unit 45.

[0272] In the high-temperature side circuit 41 according to the fourth embodiment, a high-temperature side pump 42 is connected to the inlet side of the heat medium passage 17b of the heat medium-refrigerant heat exchanger 17. The high-temperature side pump 42 is a heat medium pumping unit configured in the same manner as the above-described low-temperature side pump 32. The pumping capacity of the high-temperature side pump 42 is controlled by a control voltage output from the control device 70.

[0273] A heater core 43 is connected to the inlet side of the heat medium passage 17b of the heat medium refrigerant heat exchanger 17. Similar to the indoor condenser 16 in the above-described embodiment, the heater core 43 is disposed in the air conditioning case 61 of the indoor air conditioning unit 60. The heater core 43 is an air heat exchanger that exchanges heat between the heat medium flowing out of the heat medium refrigerant heat exchanger 17 and the blown air that has passed through the cooler core 33a. The heater core 43 radiates heat from the heat medium flowing out of the heat medium refrigerant heat exchanger 17 to the blown air, thereby heating the blown air. Therefore, the heater core 43 corresponds to an example of a heat medium radiator.

[0274] A high-temperature side flow rate adjustment unit 44 is connected to the heat medium outlet side of the heater core 43. Similar to the low-temperature side flow rate adjustment unit 37, the high-temperature side flow rate adjustment unit 44 is configured by an electric three-way flow rate adjustment valve having three inlets and outlets. The operation of the high-temperature side flow rate adjustment unit 44 is controlled by a control signal output from the control device 70.

[0275] One of the inlets and outlets of the high-temperature side flow rate adjustment unit 44 is connected to the outlet side of the heat medium passage 17b of the heat medium-refrigerant heat exchanger 17, and the other of the inlets and outlets of the high-temperature side flow rate adjustment unit 44 is connected to one of the inlets and outlets of the three-way joint-shaped high-temperature side connection unit 45. The remaining inlet and outlet of the high-temperature side flow rate adjustment unit 44 is connected to a first connection flow path 51 that constitutes the heat medium connection flow path 50.

[0276] 13 , a three-way joint-shaped high-temperature side connection part 45 is connected to the suction port side of the high-temperature side pump 42. The configuration of the high-temperature side connection part 45 is similar to the branch part 12a and the low-temperature side connection part 38 described above. As described above, one of the inlet / outlet ports of the high-temperature side connection part 45 is connected to the suction port side of the high-temperature side pump 42, and the other of the inlet / outlet ports of the high-temperature side connection part 45 is connected to the other of the inlet / outlet ports of the high-temperature side flow rate adjustment part 44. The remaining inlet / outlet port of the high-temperature side connection part 45 is connected to a second connection flow path 52.

[0277] The high-temperature side circuit 41 according to the fourth embodiment configured in this manner can circulate the heat medium by passing it through the high-temperature side pump 42, the heat medium-refrigerant heat exchanger 17, the heater core 43, the high-temperature side flow rate adjustment unit 44, the high-temperature side connection unit 45, and the high-temperature side pump 42 in this order.

[0278] That is, according to the high-temperature side circuit 41 of the fourth embodiment, the heat medium heated by the heat of the high-pressure refrigerant in the heat medium-refrigerant heat exchanger 17 flows into the heater core 43, and the blown air can be heated by the heat of the heat medium in the heater core 43. Therefore, the high-temperature side circuit 41 of the fourth embodiment corresponds to an example of the first circuit.

[0279] The heat medium circuit 30 according to the fourth embodiment has a heat medium connecting flow path 50 that connects the high-temperature side circuit 41 and the low-temperature side circuit 31 so that the heat medium can flow in and out. As shown in Fig. 13 , the heat medium connecting flow path 50 is made up of a first connecting flow path 51 and a second connecting flow path 52.

[0280] As described above, the first connecting flow path 51 connects one of the inlet / outlet ports of the high-temperature-side flow rate adjustment unit 44 arranged on the high-temperature-side circuit 41 side to one of the inlet / outlet ports of the low-temperature-side connecting unit 38 arranged on the low-temperature-side circuit 31 side. Therefore, by controlling the operation of the high-temperature-side flow rate adjustment unit 44 and opening the inlet / outlet port on the high-temperature-side flow rate adjustment unit 44 side, the heat medium can flow in and out between the high-temperature-side circuit 41 and the low-temperature-side circuit 31.

[0281] Furthermore, the second connecting flow path 52 connects one of the inlet / outlet ports of the low-temperature side flow rate adjustment unit 37 arranged on the low-temperature side circuit 31 side to one of the inlet / outlet ports of the high-temperature side connecting unit 45 arranged on the high-temperature side circuit 41 side. Therefore, by controlling the operation of the low-temperature side flow rate adjustment unit 37 and opening the inlet / outlet port on the low-temperature side flow rate adjustment unit 37 side, the heat medium can flow in and out between the high-temperature side circuit 41 and the low-temperature side circuit 31.

[0282] The low-temperature side flow rate adjustment unit 37 and the high-temperature side flow rate adjustment unit 44 are controlled when the heat medium flows in and out via the heat medium connecting flow path 50, and therefore correspond to an example of a flow rate adjustment unit.

[0283] In the fourth embodiment, the vehicle air conditioner 1 includes two heating modes as operation modes for heating the blown air, which is the object to be heated. The vehicle air conditioner 1 according to the fourth embodiment can heat the vehicle cabin using the independent circulation heating mode and the circuit-linked heating mode.

[0284] First, the independent circulation heating mode of the vehicle air conditioner 1 of the fourth embodiment will be described with reference to Fig. 14. In the independent circulation heating mode according to the fourth embodiment, heat is absorbed from a heat absorption source (air in the vehicle cabin) via the heat medium in the low-temperature side circuit 31, and is then dissipated to the blown air by the heater core 43 via the heat medium in the high-temperature side circuit 41, thereby heating the blown air. Therefore, the independent circulation heating mode according to the fourth embodiment can be considered one aspect of the heat pump heating mode.

[0285] The control device 70 causes the compressor 11 to compress and discharge the refrigerant, and throttles the low-temperature side expansion valve 19. Therefore, in the heat pump cycle 10 in the independent circulation heating mode, the refrigerant is switched to a refrigerant circuit in which the refrigerant flows and circulates through the compressor 11, the heat medium refrigerant heat exchanger 17, the low-temperature side expansion valve 19, the chiller 21, and the compressor 11 in this order.

[0286] The control device 70 controls the refrigerant discharge capacity of the compressor 11 so that the high-pressure pressure Pd detected by the high-pressure pressure sensor 72d approaches the target high-pressure PDO. The target high-pressure PDO is determined based on the target blow-out temperature TAO by referring to a control map stored in advance in the control device 70.

[0287] In addition, the control device 70 controls the throttle opening of the low-temperature side expansion valve 19 so that the superheat SHC of the refrigerant at the outlet side of the refrigerant passage 21a in the chiller 21 approaches the reference superheat KSH within a range in which the refrigerant evaporation temperature in the chiller 21 is lower than the outside air temperature Tam.

[0288] With respect to the low-temperature side circuit 31 of the heat medium circuit 30, the control device 70 determines the pumping capacity of the low-temperature side pump 32 and the opening area ratio of the three inlets and outlets of the heat medium three-way valve 34 so as to ensure the amount of heat absorption necessary to achieve the target discharge temperature. At this time, the control device 70 controls the operation of the low-temperature side flow rate adjustment unit 37 so as to fully close the inlet and outlet on the second connection flow path 52 side and simultaneously communicate the inlet and outlet on the chiller 21 side and the bypass connection unit 35 side.

[0289] As a result, in the low-temperature side circuit 31 in the independent circulation heating mode, the heat medium circulates by flowing in the following order: low-temperature side pump 32, outside-air heat exchanger 33, heat medium three-way valve 34, low-temperature side connection unit 38, chiller 21, low-temperature side flow rate adjuster 37, bypass connection unit 35, and low-temperature side pump 32. That is, in the low-temperature side circuit 31 in the independent circulation heating mode, the heat medium does not flow in or out via the heat medium connection flow path 50, and the heat medium circulates within the low-temperature side circuit 31 independently of the others.

[0290] On the other hand, for the high-temperature side circuit 41 of the heat medium circuit 30, the control device 70 determines the pumping capacity of the high-temperature side pump 42 so as to ensure the heating capacity necessary to achieve the target blowing temperature. At this time, the control device 70 controls the operation of the high-temperature side flow rate adjustment unit 44 so as to fully close the inlet / outlet on the first connection flow path 51 side and simultaneously open the inlet / outlet on the heat medium refrigerant heat exchanger 17 side and the high-temperature side connection part 45 side.

[0291] As a result, in the high-temperature side circuit 41 in the independent circulation heating mode, the heat medium circulates by flowing through the high-temperature side pump 42, the heat medium-refrigerant heat exchanger 17, the heater core 43, the high-temperature side flow rate adjuster 44, the high-temperature side connection part 45, and the high-temperature side pump 42 in that order. That is, in the high-temperature side circuit 41 in the independent circulation heating mode, the heat medium does not flow in or out via the heat medium connection flow path 50, and the heat medium circulates independently within the high-temperature side circuit 41.

[0292] Then, for the indoor air conditioning unit 60, the control device 70 determines and controls the blowing capacity of the indoor blower 62, the indoor / outdoor air ratio in the indoor / outdoor air switching device 63, and the ratio of the air mix door 64 in accordance with the operating conditions specified for the independent circulation heating mode.

[0293] As a result, in the independent circulation heating mode according to the fourth embodiment, the vehicle air conditioner 1 pumps up heat absorbed from the heat medium in the chiller 21 using the heat pump cycle 10, and uses the heat medium in the high-temperature side circuit 41 to heat the air to be blown in the heater core 43. In the low-temperature side circuit 31, heat can be absorbed from the heat absorption source (outdoor air) to the heat medium via the outside-air heat exchanger 33, and the heat of the heat medium can be absorbed by the refrigerant circulating in the chiller 21.

[0294] That is, in the independent circulation heating mode according to the fourth embodiment, similar to the heat pump heating mode described above, heat absorbed by the low-pressure side heat absorption unit 20 can be pumped up and used to heat the object to be heated (blowing air) by the high-pressure side heating unit 15. The independent circulation heating mode according to the fourth embodiment corresponds to an example of the independent circulation heating mode of the present disclosure.

[0295] Next, the circuit-linked heating mode of the vehicle air conditioner 1 of the fourth embodiment will be described with reference to Fig. 15. In the circuit-linked heating mode according to the fourth embodiment, a portion of the heat medium flowing through the high-temperature side circuit 41 is guided to the heat absorption section 20 arranged on the low-temperature side, thereby increasing the workload of the compressor 11 and heating the blown air.

[0296] The control device 70 causes the compressor 11 to compress and discharge the refrigerant, and throttles the low-temperature side expansion valve 19. Therefore, in the heat pump cycle 10 in the circuit-linked heating mode, the refrigerant is switched to a refrigerant circuit in which the refrigerant flows and circulates through the compressor 11, the heat medium refrigerant heat exchanger 17, the low-temperature side expansion valve 19, the chiller 21, and the compressor 11 in this order.

[0297] The control device 70 controls the refrigerant discharge capacity of the compressor 11 and the throttle opening of the low-temperature side expansion valve 19 to their respective target values. The target values ​​for the refrigerant discharge capacity of the compressor 11 and the throttle opening of the low-temperature side expansion valve 19 can be set, for example, in the same way as in the independent circulation heating mode.

[0298] With regard to the low-temperature side circuit 31 of the heat medium circuit 30, the control device 70 controls the operation of the heat medium three-way valve 34 so that the inlet and outlet on the low-temperature side connection part 38 side are fully closed, and at the same time, the inlet and outlet on the outside-air heat exchanger 33 side and the heat medium bypass flow path 36 side are connected to each other.

[0299] The control device 70 also controls the operation of the low-temperature-side flow rate adjuster 37 so as to fully close the inlet / outlet on the bypass connection part 35 side and simultaneously connect the inlet / outlet on the chiller 21 side and the inlet / outlet on the second connection flow path 52 side. The control device 70 then determines the pumping capacity of the low-temperature-side pump 32 so as to be in a predetermined state for the circuit-linked heating mode.

[0300] As a result, in the low-temperature side circuit 31 in the circuit-linked heating mode, the heat medium circulates by flowing in the order of the low-temperature side pump 32, the outside-air heat exchanger 33, the heat medium three-way valve 34, the heat medium bypass flow path 36, the bypass connection part 35, and the low-temperature side pump 32. That is, in the circuit-linked heating mode, the low-temperature side circuit 31 is switched to a circuit configuration in which the heat medium circulates in a part of the low-temperature side circuit 31 that passes through the outside-air heat exchanger 33 and the heat medium bypass flow path 36.

[0301] On the other hand, for the high-temperature side circuit 41 of the heat medium circuit 30, the control device 70 determines the pumping capacity of the high-temperature side pump 42 so as to ensure the heating capacity necessary to achieve the target blowing temperature. At this time, the control device 70 controls the operation of the high-temperature side flow rate adjustment unit 44 so as to communicate all of the inlet and outlets on the first connecting flow path 51 side, the heat medium refrigerant heat exchanger 17 side, and the high-temperature side connecting part 45 side.

[0302] As a result, in the high-temperature side circuit 41 in the circuit-linked heating mode, the heat medium branches into a flow that circulates in the high-temperature side circuit 41 and a flow that connects to the low-temperature side circuit 31 via the heat medium connecting flow path 50. In the flow that circulates in the high-temperature side circuit 41, the heat medium circulates by flowing through the high-temperature side pump 42, the heat medium-refrigerant heat exchanger 17, the heater core 43, the high-temperature side flow rate adjuster 44, the high-temperature side connecting part 45, and the high-temperature side pump 42 in this order.

[0303] In the flow linking with the low-temperature side circuit 31 via the heat medium connecting flow path 50, a circulation path is configured through the heat medium passage 21b of the chiller 21 via the heat medium connecting flow path 50 by control of the above-mentioned low-temperature side flow rate adjuster 37 and high-temperature side flow rate adjuster 44. In other words, the heat medium circulates by flowing through the high-temperature side pump 42, the heat medium-refrigerant heat exchanger 17, the heater core 43, the high-temperature side flow rate adjuster 44, the first connecting flow path 51, the low-temperature side connecting part 38, the chiller 21, the low-temperature side flow rate adjuster 37, the second connecting flow path 52, and the high-temperature side connecting part 45 in this order.

[0304] For the indoor air conditioning unit 60 in the circuit-linked heating mode, the control device 70 determines and controls the blowing capacity of the indoor blower 62, the indoor / outdoor air ratio in the indoor / outdoor air switching device 63, and the ratio of the air mix door 64 in accordance with the operating conditions specified for the circuit-linked heating mode.

[0305] As a result, in the circuit-linked heating mode of the fourth embodiment, the vehicle air conditioning device 1 can use the heat medium connection flow path 50 and the heat medium flow rate adjustment unit 55 to allow a portion of the heat medium flowing through the high-temperature side circuit 41 to flow into the chiller 21 that constitutes the heat absorption unit 20.

[0306] In the chiller 21, heat exchange occurs between the heat medium flowing in from the high-temperature side circuit 41 and the low-pressure refrigerant, thereby increasing the temperature of the low-pressure refrigerant in the heat pump cycle 10. As the refrigerant temperature of the low-pressure refrigerant increases, the density of the refrigerant sucked into the compressor 11 also increases, thereby increasing the workload of the compressor 11 and increasing the heating capacity of the object to be heated in the circuit-linked heating mode. The circuit-linked heating mode in the fourth embodiment corresponds to an example of the circuit-linked heating mode in the present disclosure.

[0307] As described above, in the independent circulation heating mode, heat is absorbed from the heat source (outdoor air) via the heat medium in the low-temperature side circuit 31, and the absorbed heat is pumped up by the heat pump cycle 10. The pumped up heat is radiated to the blown air, which is the object to be heated, by the heater core 43 via the heat medium in the high-temperature side circuit 41, thereby realizing heating of the object to be heated. Therefore, the heating capacity in the independent circulation heating mode according to the fourth embodiment is affected by the amount of heat absorbed in the low-temperature side circuit 31, as in the heat pump heating mode of the above-described embodiments.

[0308] On the other hand, in the circuit-linked heating mode according to the fourth embodiment, the circuit configuration of the heat pump cycle 10 is the same as that in the independent circulation heating mode, but the configuration of the heat medium circulation path in the heat medium circuit 30 is different.

[0309] 15 , in the circuit-linked heating mode, a part of the heat medium flowing out of the heat medium-refrigerant heat exchanger 17 circulates through the heater core 43 in the high-temperature side circuit 41, while the other part of the heat medium flows through the heat medium connecting flow path 50 and the chiller 21. In other words, a part of the heating capacity of the heat medium in the heat medium-refrigerant heat exchanger 17 is used to heat the object to be heated (blowing air), and the other part of the heating capacity is used to increase the temperature of the low-pressure refrigerant through the chiller 21.

[0310] Here, it is considered that the heating capacity of the heat medium in the heat medium refrigerant heat exchanger 17 does not increase instantaneously before and after switching from the independent circulation heating mode to the circuit-linked heating mode, but remains approximately the same.

[0311] When the mode is switched to the circuit-linked heating mode, part of the heat medium flowing out of the heat medium-refrigerant heat exchanger 17 is used to heat the blown air via the heater core 43, while the other part of the heat medium is guided to the chiller 21 side via the heat medium connecting flow path 50 and the heat medium flow rate adjuster 55. That is, the blown air is heated by part of the heat amount of the heat medium warmed by the heat of the high-pressure refrigerant in the heater core 43. Therefore, it is considered that the heating capacity of the blown air is temporarily reduced immediately after switching from the independent circulation heating mode to the circuit-linked heating mode.

[0312] Here, in the vehicle air conditioning system 1 according to the fourth embodiment, when switching from the independent circulation heating mode to the circuit-linked heating mode, switching control is performed to suppress fluctuations in the heating capacity of the object to be heated due to differences in the operating mode.

[0313] As described above, the heating capacity in the independent circulation heating mode and the circuit-linked heating mode corresponds to the amount of heat absorbed by the heat absorption unit 20 and the workload of the compressor 11, respectively, and is therefore affected by the low pressure of the refrigerant in the heat pump cycle 10. In order to suppress fluctuations in heating capacity during mode switching and to make the fluctuations shorter in duration, it is desirable to quickly achieve a state in which the low pressure required in the independent circulation heating mode is low, in order to increase the workload of the compressor 11 in the circuit-linked heating mode.

[0314] In order to increase the low pressure of the refrigerant in the heat pump cycle 10, it is necessary to increase the heat quantity of the refrigerant. Therefore, as one of the operations in the switching control for increasing the low pressure of the heat pump cycle 10 and suppressing fluctuations in the heating capacity, an operation of suppressing the amount of heat radiation on the high pressure side of the heat pump cycle 10 can be considered.

[0315] As a result, by suppressing the amount of heat radiation on the high-pressure side of the heat pump cycle 10, the refrigerant discharged from the compressor 11 retains heat, making it possible to increase the low-pressure side of the heat pump cycle 10. This allows the low-pressure side of the heat pump cycle 10 to be quickly increased to a desired level, making it possible to quickly eliminate fluctuations in heating capacity caused by switching of the operation mode. Hereinafter, the operation of suppressing the amount of heat radiation on the high-pressure side of the heat pump cycle 10 during operation mode switching control is referred to as a limiting operation.

[0316] Furthermore, one possible operation in the switching control for increasing the low pressure of the heat pump cycle 10 and suppressing fluctuations in heating capacity is to maintain the amount of heat absorption on the low pressure side of the heat pump cycle 10 as much as possible.

[0317] As described above, in the independent heating mode before switching, the heat absorption section 20 on the low-pressure side of the heat pump cycle 10 absorbs heat via the heat medium in the heat medium circuit 30. The amount of heat absorbed by the heat absorption section 20 constitutes the amount of heat of the refrigerant flowing on the low-pressure side.

[0318] Taking this into consideration, when switching from the independent circulation heating mode to the circuit-linked heating mode, heat absorption continues from the independent circulation heating mode in the heat absorption unit 20. However, switching control when switching the operation mode is performed within a range that allows the heat absorption amount in the heat absorption unit 20 to be maintained, thereby suppressing a decrease in the low-pressure side of the heat pump cycle 10. Hereinafter, the operation for maintaining the heat absorption amount on the low-pressure side of the heat pump cycle 10 as much as possible during switching control of the operation mode is referred to as heat absorption amount ensuring operation.

[0319] Next, the switching control when switching from the independent circulation heating mode to the circuit-linked heating mode in the vehicle air conditioner 1 according to the fourth embodiment will be described in detail with reference to FIG. 16, including the operation of each component.

[0320] 16 , the automotive air conditioner 1 has been operating in the independent circulation heating mode since time ta. In the automotive air conditioner 1 operating in the independent circulation heating mode, the controller 70 controls the operation of the compressor 11, the low-temperature side expansion valve 19, the low-temperature side pump 32, the heat medium three-way valve 34, and the low-temperature side flow rate adjuster 37. The controller 70 also controls the operation of the high-temperature side pump 42, the high-temperature side flow rate adjuster 44, the interior blower 62, the air mix door 64, etc.

[0321] In the fourth embodiment, at time tb, a decision is made to switch the operating mode from the independent circulation heating mode to the circuit-linked heating mode, and switching control is initiated in the vehicle air conditioner 1. The switching control can be initiated, for example, when the amount of heat absorbed by the heat absorption unit 20 is insufficient for the required heating capacity, and the required heating capacity cannot be met in the independent circulation heating mode. The relationship between the required heating capacity and the amount of heat absorption is determined based on the relationship between the target blowout temperature of the conditioned air and the temperature of the heat absorption target (air) at the heat absorption unit 20.

[0322] At time tb, when control for switching from the independent circulation heating mode to the circuit-linked heating mode begins, the operating modes of the rotation speed of the compressor 11, the throttle opening of the low-temperature side expansion valve 19, the pressure-feeding capacity of the low-temperature side pump 32, the blowing capacity of the indoor blower 62, and the opening of the air mix door 64 are controlled.

[0323] The rotation speed of compressor 11 is adjusted from the rotation speed in the independent circulation heating mode to a predetermined rotation speed determined by the switching control, and the throttle opening of low-temperature side expansion valve 19 is switched from a mode in which the throttle opening fluctuates in the independent circulation heating mode to a mode in which the throttle opening is maintained at the predetermined throttle opening determined by the switching control.

[0324] The control device 70 then controls the operation of the low-temperature side flow rate adjustment unit 37 and the high-temperature side flow rate adjustment unit 44 that constitute the heat medium flow rate adjustment unit 55, allowing the heat medium to flow in and out between the low-temperature side circuit 31 and the high-temperature side circuit 41.

[0325] As a result, during the switching control, the heat pump cycle 10 is switched to a refrigerant circuit similar to that in the independent circulation heating mode, although the refrigerant discharge capacity of the compressor 11 and the pressure reduction amount in the low-temperature side expansion valve 19 are different.

[0326] In the heat medium circuit 30 during switching control, the circulation of the heat medium in the low-temperature side circuit 31 in the independent circulation heating mode and the circulation of the heat medium in the high-temperature side circuit 41 are continued, and at the same time, the flow of the heat medium in and out via the heat medium connecting flow path 50 is permitted.

[0327] As a result, part of the heat medium heated by the heat of the high-pressure refrigerant in the high-temperature side circuit 41 flows into the low-temperature side circuit 31 via the second connecting flow path 52, and heat is absorbed by the low-pressure refrigerant in the chiller 21. Therefore, under switching control, while heat absorption is continued in the heat absorption unit 20 from the independent circulation heating mode, the operation of allowing the heat medium to flow in and out between the low-temperature side circuit 31 and the high-temperature side circuit 41 via the heat medium connecting flow path 50 corresponds to an example of an operation for ensuring the amount of heat absorption.

[0328] In other words, the heat absorption amount ensuring operation according to the fourth embodiment can be said to be an operation for ensuring the heat absorption amount for the heat pump cycle 10 by the heat absorption amount from the heat absorption source (outdoor air) and the heat absorption amount from the heat medium derived from the high-pressure refrigerant (discharged refrigerant). Then, a part of the heat medium flowing out from the chiller 21 flows into the high-temperature side circuit 41 via the first connecting flow path 51, and the heat contained in the high-pressure refrigerant is dissipated in the heat medium-refrigerant heat exchanger 17.

[0329] Furthermore, the airflow rate of the indoor blower 62 is controlled to a predetermined value for the switching control, and operates to maintain the predetermined value during the switching control. Because the airflow rate of the indoor blower 62 during the switching control is set lower than the airflow rate in the independent circulation heating mode, after the elapse of time tb, the airflow rate of the indoor blower 62 is controlled to gradually decrease toward the predetermined value during the switching control.

[0330] That is, in the switching control, the supply amount of the object to be heated (blow air) supplied to the heater core 43 constituting the heating unit 15 is limited by controlling the operation of the indoor blower 62. Therefore, in the switching control, the operation of limiting the blowing capacity of the indoor blower 62 to a value lower than that in the independent circulation heating mode ultimately limits the destination to which the heat of the high-pressure refrigerant is dissipated, and therefore corresponds to an example of a limiting operation in the switching control.

[0331] The opening degree of the air mix door 64 is controlled to a predetermined value that is set so that the opening degree of the cool air bypass passage 65 is larger than in the independent circulation heating mode. That is, during the switching operation, the air mix door 64 is controlled so that most of the blown air that has passed through the cooler core 33a flows bypassing the heater core 43.

[0332] Here, if the amount of blown air supplied to the heater core 43 is limited to a value lower than that in the independent circulation heating mode, the amount of heat radiated from the high-pressure refrigerant in the heat pump cycle 10 in the heating unit 15 is also reduced compared to that in the independent circulation heating mode. Therefore, in the switching control, the operation of adjusting the opening degree of the air mix door 64 corresponds to an example of a limiting operation in the switching control.

[0333] In this way, when the operation control of each component related to the switching control is performed after the time tb has elapsed, the high pressure of the refrigerant in the heat pump cycle 10 decreases. In Fig. 16, the time point at which the various operations in the switching control are completed is indicated as time tc.

[0334] After time tc, while the switching control is continued, the above-mentioned limiting operation and heat absorption amount ensuring operation are also continued. In the fourth embodiment, the state in which the limiting operation and the heat absorption amount ensuring operation are performed in parallel in the switching control is also referred to as the first state of the switching control.

[0335] Since the limiting operation limits the amount of heat dissipated from the high-pressure side of the refrigerant in the heat pump cycle 10, the value of the high-pressure refrigerant pressure increases over time from the start of the limiting operation. That is, the limiting operation in the switching control can improve the heating capacity of the heat pump cycle 10.

[0336] Furthermore, due to the heat absorption amount securing operation, the heat absorption amount in the heat absorption unit 20 on the low-pressure side of the heat pump cycle 10 is greater than or equal to that in the independent circulation heating mode. This is because the heat medium heated by the heat of the high-pressure refrigerant is introduced directly into the heat medium passage 21b of the chiller 21 via the heat medium connecting flow path 50.

[0337] As a result, the low-pressure refrigerant pressure rises rapidly from the start of the heat absorption amount ensuring operation. Similarly, the temperature of the low-pressure refrigerant flowing through the heat absorption unit 20 (i.e., the temperature of the low-pressure refrigerant flowing out from the refrigerant passage 21a of the chiller 21) also rises rapidly from time tc. In other words, the heat absorption amount ensuring operation in the switching control quickly increases the density of the refrigerant sucked into the compressor 11, thereby increasing the amount of work performed by the compressor 11.

[0338] As a switching control, the limiting operation and the heat absorption amount ensuring operation are continuously performed from time tc, and the refrigerant temperature in the refrigerant passage 21a of the chiller 21 reaches a predetermined reference chiller-side temperature KTc. The refrigerant temperature in the refrigerant passage 21a of the chiller 21 being equal to or higher than the predetermined reference chiller-side temperature KTc is an example of a heat absorption stop condition.

[0339] In the fourth embodiment, the time when the temperature of the low-pressure refrigerant in the refrigerant passage 21a of the chiller 21 reaches the reference chiller-side temperature KTc and the heat absorption stop condition is satisfied is referred to as time tdx. The time tdx indicates the time when the heat absorption amount in the heat absorption unit 20 can no longer be sufficiently secured. Therefore, even if the heat absorption amount securing operation is performed, it is difficult to use the heat absorption amount to raise the low-pressure refrigerant.

[0340] In the heat absorption amount ensuring operation of the fourth embodiment, in addition to heat absorption using the outdoor air as a heat absorption source, as in the above-described embodiments, heat is also absorbed from the heat medium flowing in from the high-temperature side circuit 41. By using the heat medium from the high-temperature side circuit 41, it becomes easier to further increase the temperature of the low-pressure refrigerant. That is, in the fourth embodiment, the time required from time tc to time tdx can be made shorter than the time required from time tc to time td in the above-described embodiments.

[0341] After the time tdx has elapsed, the heat absorption amount ensuring operation is terminated. Specifically, with regard to heat absorption by the heat absorption unit 20 during switching control, heat absorption from the outdoor air is stopped. For example, the operation of the heat medium three-way valve 34 is controlled so that the inlet / outlet on the low-temperature side connection unit 38 side is fully closed, and at the same time, the inlet / outlet on the outdoor air heat exchanger 33 side and the inlet / outlet on the heat medium bypass flow path 36 side are connected to each other. Then, the operation of the low-temperature side flow rate adjustment unit 37 is controlled so that the inlet / outlet on the bypass connection unit 35 side is fully closed, and at the same time, the inlet / outlet on the chiller 21 side and the inlet / outlet on the second connection flow path 52 side are connected to each other.

[0342] As a result, the circulation path of the heat medium in the low-temperature side circuit 31 is switched to a circulation path that passes through the outdoor air heat exchanger 33 and the heat medium bypass flow path 36 and does not pass through the chiller 21, thereby stopping heat absorption from the outdoor air that is the heat absorption source. Note that it is also possible to employ a mode in which the low-temperature side pump 32 is stopped in order to stop heat absorption from the heat absorption source.

[0343] By stopping the heat absorption amount securing operation when the heat absorption stop condition is satisfied in this way, it is possible to suppress the waste of energy required for the heat absorption amount securing operation and realize energy-efficient switching control.

[0344] Even after the heat absorption amount securing operation is completed, the refrigerant and heat medium circulation and the limiting operation in the heat pump cycle 10 under the switching control continue. This state is called the second state of the switching control. Because the limiting operation is continuously performed in the second state of the switching control, the high-pressure pressure, low-pressure pressure, and low-pressure-side refrigerant temperature of the refrigerant in the heat pump cycle 10 increase over time even after the time tdx and the end of the heat absorption amount securing operation.

[0345] As described above, the switching control is executed to suppress fluctuations in heating capacity when switching from the independent circulation heating mode to the circuit-linked heating mode. As one of the measures to suppress fluctuations in heating capacity, in the second state of the switching control, it is determined whether the high-pressure refrigerant in the heat pump cycle 10 has increased to a state where the heating capacity in the circuit-linked heating mode is equivalent to that in the independent circulation heating mode.

[0346] Specifically, it is determined whether the high-pressure pressure of the refrigerant in the heat pump cycle 10 under switching control is higher than a predetermined reference high-pressure pressure KPd. If the high-pressure pressure in the heat pump cycle 10 under switching control is higher than the reference high-pressure pressure KPd, the circuit-linked heating mode can exhibit heating capacity equivalent to that in the independent circulation heating mode, thereby suppressing fluctuations in heating capacity.

[0347] Another method for suppressing fluctuations in heating capacity when switching to the circuit-linked heating mode is to increase the workload of the compressor 11 to a level equivalent to the heating capacity in the independent circulation heating mode in the second state of the switching control. That is, in the second state of the switching control, it is determined whether the low-pressure pressure of the refrigerant in the heat pump cycle 10 is higher than the reference low-pressure pressure KPs.

[0348] The reference low pressure KPs indicates the low pressure of the refrigerant in the heat pump cycle 10, and is set so that the workload of the compressor 11 in the circuit-linked heating mode is equivalent to the heating capacity in the independent circulation heating mode. When the low pressure in the heat pump cycle 10 under switching control is higher than the reference low pressure KPs, the circuit-linked heating mode can exhibit the same heating capacity as the independent circulation heating mode, thereby suppressing fluctuations in the heating capacity.

[0349] 16 , when the switching control transitions to the second state after the time tdx has elapsed, the high-pressure pressure and the low-pressure pressure in the heat pump cycle 10 gradually increase. The time te is the time when either the high-pressure pressure in the heat pump cycle 10 becomes equal to or greater than the reference high-pressure pressure KPd or the low-pressure pressure in the heat pump cycle 10 becomes equal to or greater than the reference low-pressure pressure KPs.

[0350] 16 shows an example in which the high-pressure pressure of the heat pump cycle 10 becomes equal to or greater than the reference high-pressure pressure KPd and the low-pressure pressure of the heat pump cycle 10 becomes equal to or greater than the reference low-pressure pressure KPs simultaneously. The time te may be determined as the time when either of the two conditions described above is satisfied earlier. Furthermore, in order to reliably suppress fluctuations in heating capacity, the time te may be determined as the time when both the high-pressure condition and the low-pressure condition are satisfied.

[0351] When the high-pressure condition or the low-pressure condition of the refrigerant in the heat pump cycle 10 is satisfied and the time te has elapsed, the switching control is terminated and the system transitions to the circuit-linked heating mode. By terminating the limiting operation and transitioning to the circuit-linked heating mode on the condition that the high-pressure condition of the refrigerant is satisfied, the circuit-linked heating mode is started with the heating capacity of the heat pump cycle 10 at a predetermined level (i.e., the level before the switching control). This allows the circuit-linked heating mode to be started with fluctuations in the heating capacity of the blown air, which is the object to be heated, suppressed.

[0352] Furthermore, by terminating the limiting operation and switching to the circuit-linked heating mode when the low-pressure condition of the refrigerant is satisfied, the circuit-linked heating mode is started when the workload of the compressor 11 reaches a predetermined level (i.e., the level before switching control). Even in this case, the circuit-linked heating mode can be started while suppressing fluctuations in the heating capacity of the blown air, which is the object to be heated.

[0353] According to the fourth embodiment, when switching from the independent circulation heating mode to the circuit-linked heating mode, the switching control is performed to execute the limiting operation, thereby enabling the circuit-linked heating mode to be started with a sufficiently increased heating capacity of the heat pump cycle 10. This makes it possible to switch the operation mode while minimizing the difference in heating capacity between the independent circulation heating mode and the circuit-linked heating mode due to the configuration of the refrigerant circuit.

[0354] 16 , as a limiting operation of the switching control, the operation of the indoor blower 62 is controlled to limit the amount of air supplied to the heater core 43 constituting the heating unit 15. By limiting the amount of air sent by the indoor blower 62, the amount of heat dissipated on the high-pressure side of the heat pump cycle 10 can be limited, and the heating capacity of the high-pressure side of the heat pump cycle 10 can be improved.

[0355] Furthermore, as a limiting operation of the switching control, the opening degree of the air mix door 64 is controlled to limit the amount of air supplied to the heater core 43 constituting the heating unit 15. By operating the air mix door 64, it is possible to limit the amount of air supplied to the heater core 43 from the viewpoint of the air flow path of the air to be heated. Therefore, the limiting operation related to the operation control of the air mix door 64 can ensure sufficient heating capacity of the heat pump cycle 10 before switching to the circuit-linked heating mode.

[0356] 16, the switching control executes the limiting operation and the heat absorption amount ensuring operation in parallel. That is, by performing the limiting operation and the heat absorption amount ensuring operation in parallel, it is possible to utilize both the heating capacity of the high-pressure side of the heat pump cycle 10 and the workload of the compressor 11 due to the low-pressure side of the heat pump cycle 10. As a result, when switching from the independent circulation heating mode to the circuit-linked heating mode, the period during which the heating capacity of the object to be heated fluctuates can be shortened and the fluctuations can be kept small.

[0357] Similarly to the independent circulation heating, the heat absorption amount ensuring operation in the fourth embodiment is realized by absorbing heat from the heat medium flowing in from the high-temperature side circuit 41 via the heat medium connecting flow path 50 in parallel with the operation of absorbing heat from the low-pressure refrigerant in the chiller 21 from the heat absorption source (outdoor air). This makes it possible to utilize part of the heat of the refrigerant discharged from the compressor 11 in addition to the heat absorption source (outdoor air), thereby increasing the low-pressure pressure of the heat pump cycle 10 in a shorter period of time and improving the workload of the compressor 11.

[0358] As shown by time tdx in Fig. 16, the heat absorption amount ensuring operation in the switching control is terminated when the heat absorption stop condition is satisfied and the heat absorption amount becomes smaller than a predetermined reference value. That is, in the switching control, the heat absorption amount ensuring operation can be efficiently executed, and fluctuations in the heating capacity can be suppressed.

[0359] 16 , if the heat absorption stop condition is satisfied while the heat absorption amount ensuring operation is being performed, the supply amount of the heat medium circulating through the low-temperature side circuit 31 to the chiller 21 is set to 0. Specifically, the heat medium circulation path in the low-temperature side circuit 31 is switched to a circulation path that excludes the heat medium passage 21b of the chiller 21 and passes through the outside-air heat exchanger 33 and the heat medium bypass flow path 36. This makes it possible to end the heat absorption amount ensuring operation with simple operational control.

[0360] As described above, according to the vehicle air conditioner 1 of the fourth embodiment, in the switching control when switching from the independent circulation heating mode to the circuit-linked heating mode, a limiting operation is performed to limit the amount of heat dissipation from the heater core 43 that constitutes the heating unit 15. By performing the limiting operation in the switching control, the heating capacity of the high-pressure side of the heat pump cycle 10 can be sufficiently increased, and fluctuations in heating capacity between the independent circulation heating mode and the circuit-linked heating mode can be minimized.

[0361] 16 , as a limiting operation of the switching control, the operation of the indoor blower 62 is controlled to limit the amount of air supplied to the heater core 43 constituting the heating unit 15. By limiting the amount of air sent by the indoor blower 62, the amount of heat dissipated on the high-pressure side of the heat pump cycle 10 can be limited, and the heating capacity of the high-pressure side of the heat pump cycle 10 can be improved.

[0362] Furthermore, as a limiting operation in the switching control, the opening degree of the air mix door 64 is controlled to limit the amount of air supplied to the heater core 43 constituting the heating unit 15. By operating the air mix door 64, it is possible to limit the amount of air supplied to the heater core 43 in terms of the air flow path of the air to be heated. Therefore, the limiting operation related to the operation control of the air mix door 64 can ensure sufficient heating capacity of the heat pump cycle 10 before switching to the circuit-linked heating mode.

[0363] 16 , the limiting operation in the switching control releases the restriction on the heat radiation amount when the high-pressure pressure of the heat pump cycle 10 becomes equal to or greater than the reference high-pressure pressure KPd. The state in which the high-pressure pressure becomes equal to or greater than the reference high-pressure pressure indicates that the heating capacity of the heat pump cycle 10 has improved to a predetermined standard. Therefore, from the viewpoint of the heating capacity of the heat pump cycle 10, the limiting operation can be terminated when fluctuations in the heating capacity can be suppressed, and the system can transition to the circuit-linked heating mode.

[0364] Furthermore, the limiting operation in the switching control releases the limit on the heat dissipation amount when the low-pressure pressure of the heat pump cycle 10 becomes equal to or greater than the reference low-pressure pressure KPs. The state in which the low-pressure pressure becomes equal to or greater than the reference low-pressure pressure KPs indicates that the workload of the compressor 11 has increased to a predetermined standard. Therefore, the limiting operation can be terminated and the system can transition to the circuit-linked heating mode when fluctuations in the heating capacity can be suppressed from the perspective of the workload of the compressor 11.

[0365] 16 , in the switching control for switching from the independent circulation heating mode to the circuit-linked heating mode, the limiting operation and the heat absorption amount ensuring operation are performed in parallel, and then the mode is switched to the circuit-linked heating mode. The limiting operation improves the heating capacity of the heat pump cycle 10, while the heat absorption amount ensuring operation increases the workload of the compressor 11. Therefore, by performing the limiting operation and the heat absorption amount ensuring operation in parallel, the required time for the switching control can be shortened, and fluctuations in heating capacity can be suppressed in a short period of time.

[0366] The present disclosure is not limited to the above-described embodiments, and various modifications can be made as follows within the scope of the present disclosure.

[0367] In the above-described embodiment, the heat pump cycle device according to the present disclosure is applied to the vehicle air conditioner 1 mounted on an electric vehicle, but the present disclosure is not limited to this embodiment. For example, the object to be heated in the heat pump cycle device according to the present disclosure is not limited to the blown air to be air-conditioned. That is, the heat pump cycle device according to the present disclosure may be applied to, for example, a water heater in which the object to be heated is water.

[0368] In the above-described embodiment, the heat absorption object and heat absorption source in the heat pump cycle device are the outdoor air, the heat medium, etc., but the present invention is not limited to this. For example, the heat absorption source may be the exhaust heat of devices mounted on an electric vehicle, or the exhaust heat generated in a battery, inverter, PCU, transaxle, ADAS control device, etc. may be used as the heat absorption source.

[0369] The inverter supplies power to the motor generator, etc. The PCU is a power control unit that transforms electricity and distributes power. The transaxle is a power transmission mechanism that integrates the transmission, differential gear, etc. The ADAS control device is a control device for the advanced driver assistance system.

[0370] The heating unit 15 in the above-described embodiment is configured to directly dissipate heat from the high-pressure refrigerant to the object to be heated, such as the indoor condenser 16, and to indirectly dissipate heat from the high-pressure refrigerant to the object to be heated, such as the heat medium refrigerant heat exchanger 17 and the high-temperature side circuit 41. In other words, the heating unit 15 is not limited to a state on the way to the object to be heated, as long as the heat from the high-pressure refrigerant is ultimately used to heat the object to be heated.

[0371] In addition, the heat absorption unit 20 in the above-described embodiment may be configured to have a chiller 21 as a heat absorber, an outdoor air heat absorber 22, or both the chiller 21 and the outdoor air heat absorber 22. However, the heat absorption unit 20 is not limited to this. The heat absorption unit 20 may be configured with more heat absorbers as long as it is capable of absorbing heat from a heat absorption source.

[0372] In the above-described embodiment, the conditions for ending the limiting operation are when the high-pressure pressure becomes equal to or greater than the reference high-pressure pressure KPd and when the low-pressure pressure becomes equal to or greater than the reference low-pressure pressure KPs. The reference high-pressure pressure KPd and the reference low-pressure pressure KPs are determined taking into consideration the application of the vehicle air conditioning system 1. That is, the reference high-pressure pressure KPd and the reference low-pressure pressure KPs are determined so that the change in heating capacity before and after switching is small enough that the occupants do not feel any significant discomfort.

[0373] In the first and second embodiments described above, the heat pump cycle 10 is configured as a receiver cycle, and in the third embodiment, the heat pump cycle 10 is configured as an accumulator cycle, but the present disclosure is not limited to this. The arrangement of the gas-liquid separation unit is not limited to the heat pump cycle according to the present disclosure, and heat pump cycles of various configurations can be applied.

[0374] The heat pump cycle device disclosed in this specification has the following features: (Item 1) a compressor (11) that compresses and discharges a refrigerant, a branching section (12a) that branches the flow of the refrigerant discharged from the compressor, a heating section (15) that heats an object to be heated using the refrigerant flowing out of one outlet of the branching section as a heat source, a low-temperature side pressure reduction section (19, 26, 27) that reduces the pressure of the refrigerant flowing out of the heating section, a bypass passage (13) that circulates the other of the refrigerants branched at the branching section, a bypass side pressure reduction section (14) that adjusts the flow rate of the refrigerant flowing through the bypass passage, a merging section (12b, 25) that merges the flow of the refrigerant flowing out of the bypass side pressure reduction section and the flow of the refrigerant flowing out of the low-temperature side pressure reduction section and causes them to flow toward the suction port side of the compressor, and a heat absorption section (20) that absorbs heat from an object to be heat-absorbed by the refrigerant flowing out of at least the low-temperature side pressure reduction section. a control unit (70) that performs control to switch between a first heating mode in which all of the refrigerant discharged from the compressor flows into the heating unit via the branch unit, and the heat absorbed from the heat absorption object is pumped up by the heat absorption unit to heat the object to be heated; and a second heating mode in which a portion of the refrigerant discharged from the compressor flows into the bypass passage via the branch unit, the refrigerant flowing out from the bypass side pressure reduction unit is guided to the junction unit, and another portion of the refrigerant discharged from the compressor flows into the heating unit via the branch unit, and the refrigerant flowing out from the heating unit is joined at the junction unit with the flow of refrigerant from the bypass side pressure reduction unit to be drawn into the compressor, wherein, when switching from the first heating mode to the second heating mode, the control unit performs a limiting operation to limit an amount of heat radiation in the heating unit in the first heating mode to a low level, and completes the switching to the second heating mode after performing the limiting operation.(Item 2) The heat pump cycle apparatus according to item 1, wherein the heating unit includes a radiator (16) that radiates heat from the refrigerant that has flowed into the heating unit, and a supply adjustment unit (62, 64) that adjusts the supply amount of the object to be heated supplied to the radiator, and the limiting operation controls operation of the supply adjustment unit to limit the supply amount of the object to be heated to the radiator to be lower than a predetermined reference amount. (Item 3) The heat pump cycle apparatus according to item 1 or 2, wherein the control unit terminates the limiting operation and releases the limit on the amount of heat radiation from the heating unit when the heating capacity of the heating unit exceeds a predetermined reference heating capacity (KPd) while the limiting operation is being performed. (Item 4) The heat pump cycle apparatus according to item 1 or 2, wherein the control unit terminates the limiting operation and releases the limit on the amount of heat radiation from the heating unit when the pressure of the refrigerant in the heat absorption unit exceeds a predetermined reference low pressure (KPs) while the limiting operation is being performed. (Item 5) When switching from the first heating mode to the second heating mode, the control unit executes, in parallel with the limiting operation, a heat absorption amount ensuring operation for ensuring a heat absorption amount in the heat absorption unit by using heat possessed by the refrigerant discharged from the compressor and heat absorbed by the heat absorption unit from the heat absorption object, and the heat pump cycle apparatus according to any one of items 1 to 4 completes the switching to the second heating mode after executing the heat absorption amount ensuring operation and the limiting operation.(Item 6) A compressor (11) that compresses and discharges a refrigerant, a branching section (12a) that branches the flow of the refrigerant discharged from the compressor, a heating section (15) that heats an object to be heated using the refrigerant flowing out from one outlet of the branching section as a heat source, a low-temperature side pressure reduction section (19, 26, 27) that reduces the pressure of the refrigerant flowing out from the heating section, a bypass passage (13) that circulates the other of the refrigerants branched at the branching section, a bypass side pressure reduction section (14) that adjusts the flow rate of the refrigerant flowing through the bypass passage, a merging section (12b, 25) that merges the flow of the refrigerant flowing out from the bypass side pressure reduction section and the flow of the refrigerant flowing out from the low-temperature side pressure reduction section and causes them to flow out to a suction port side of the compressor, and a heat absorption section (20) that absorbs heat from an object to be heat-absorbed by the refrigerant flowing out from at least the low-temperature side pressure reduction section, a control unit (70) that performs control to switch between a first heating mode in which all of the refrigerant discharged from the compressor flows into the heating unit via the branching unit, and the heat absorbed from the heat absorption object is pumped up by the heat absorption unit to heat the object to be heated, and a second heating mode in which a part of the refrigerant discharged from the compressor flows into the bypass passage via the branching unit, and the refrigerant flowing out from the bypass side pressure reduction unit is guided to the junction unit, and another part of the refrigerant discharged from the compressor flows into the heating unit via the branching unit, and the refrigerant flowing out from the heating unit is joined at the junction unit with the flow of the refrigerant from the bypass side pressure reduction unit to be drawn into the compressor, When switching from the first heating mode to the second heating mode, the control unit performs a heat absorption amount ensuring operation to ensure the amount of heat absorption in the heat absorption unit using the heat contained in the refrigerant discharged from the compressor and the heat absorbed from the heat absorption object in the heat absorption unit, and after performing the heat absorption amount ensuring operation, the heat pump cycle device completes switching to the second heating mode.(Item 7) The heat pump cycle apparatus according to item 6, wherein, when operating in the first heating mode, the heat absorption amount ensuring operation continues heat absorption from the heat absorption object in the heat absorption unit, while simultaneously causing a portion of the refrigerant discharged from the compressor to flow into the bypass passage via the branching portion and directing the refrigerant flowing out from the bypass side pressure reducing portion to the junction portion. (Item 8) The heat pump cycle apparatus according to item 6 or 7, wherein, when the heat absorption amount ensuring operation is being performed, the control unit suppresses heat absorption in the heat absorption unit if a heat absorption stop condition is met in which an amount of heat absorbed by the refrigerant from the heat absorption object in the heat absorption unit is lower than a predetermined reference heat absorption amount (KTc). (Item 9) The heat pump cycle apparatus according to item 8, wherein, when the heat absorption amount ensuring operation is being performed and the heat absorption stop condition is met, the control unit reduces the amount of the heat absorption object supplied to the heat absorption unit to suppress heat absorption in the heat absorption unit. (Item 10) The heat pump cycle device according to Item 8, further comprising a refrigerant bypass flow path connected to guide the flow of the refrigerant flowing out from the heating section to the junction section, bypassing the heat absorption section (21), wherein the control section, when the heat absorption stop condition is satisfied while the heat absorption amount securing operation is being performed, uses the refrigerant bypass flow path to stop the supply of the refrigerant to the heat absorption section (21), thereby suppressing heat absorption in the heat absorption section.(Item 11) A heat pump cycle (10) including: a compressor (11) that compresses and discharges a refrigerant; a heat medium refrigerant heat exchanger (17) that dissipates heat from the high-pressure refrigerant discharged from the compressor to a heat medium; a pressure reducing section (19) that reduces the pressure of the refrigerant flowing out of the heat medium refrigerant heat exchanger; and a chiller (21) that exchanges heat between the refrigerant decompressed in the pressure reducing section and the heat medium, causing the refrigerant to absorb heat. a heat medium circuit (30) including: a first circuit (41) configured to allow the heat medium flowing out of the heat medium refrigerant heat exchanger to circulate and including a heat medium radiator (43) that radiates heat possessed by the heat medium to a heating object; a second circuit (31) configured to allow the heat medium circulating through the chiller to circulate and having a heat medium heat absorber (33) that absorbs heat from a heat absorption object by heat exchange with the heat medium; a heat medium connecting flow path (50) that connects between the first circuit and the second circuit to allow the heat medium to flow in and out; and a flow rate adjusting unit (55) that adjusts the flow rate of the heat medium flowing in and out between the first circuit and the second circuit via the heat medium connecting flow path; and an independent circulation heating mode in which heat derived from the heat absorption object is absorbed and pumped up from the heat medium circulating independently in the second circuit, and the heating object is heated by the heat medium radiator via the heat medium circulating independently in the first circuit; and a control unit (70) that performs control to switch to a circuit-linked heating mode in which a portion of the heat medium that has circulated through the heat medium refrigerant heat exchanger is circulated through the chiller via the heat medium connecting flow path, and another portion of the heat medium that has circulated through the heat medium refrigerant heat exchanger is circulated through the first circuit via the heat medium radiator, thereby heating the object to be heated with the heat medium radiator, wherein when switching from the independent circulation heating mode to the circuit-linked heating mode, the control unit performs a limiting operation to limit the amount of heat radiation in the heat medium radiator in the independent circulation heating mode to a low level, and after performing the limiting operation, completes the switch to the circuit-linked heating mode.(Item 12) The heat pump cycle apparatus according to item 11, further comprising a supply adjustment unit (62, 64) that adjusts the supply amount of the object to be heated supplied to the heat medium radiator, wherein the limiting operation controls operation of the supply adjustment unit to limit the supply amount of the object to be heated to the heat medium radiator to be lower than a predetermined reference amount. (Item 13) The heat pump cycle apparatus according to item 11 or 12, wherein the control unit terminates the limiting operation and releases the limit on the amount of heat radiation in the heat medium radiator when a heating capacity for the heat medium circulating through the first circuit exceeds a predetermined reference (KPd) while the limiting operation is being performed. (Item 14) The heat pump cycle apparatus according to item 11 or 12, wherein the control unit terminates the limiting operation and releases the limit on the amount of heat radiation in the heat medium radiator when a pressure of the refrigerant in the chiller exceeds a predetermined reference low pressure (KPs) while the limiting operation is being performed. (Item 15) When switching from the independent circulation heating mode to the circuit-linked heating mode, the control unit executes, in parallel with the limiting operation, a heat absorption amount ensuring operation to ensure a heat absorption amount in the chiller by using heat absorbed from a heat absorption object by the heat medium heat absorber and heat possessed by the heat medium led from the first circuit to the chiller via the heat medium connection flow path, and the heat pump cycle apparatus according to any one of Items 11 to 14 completes the switching to the circuit-linked heating mode after executing the heat absorption amount ensuring operation and the limiting operation.

[0375] Although the present disclosure has been described with reference to the embodiments, it is understood that the present disclosure is not limited to the embodiments or structures. The present disclosure also encompasses various modifications and equivalent modifications. In addition, various combinations and forms, including only one element, more than one element, or less than one element, are also within the scope and spirit of the present disclosure.

Claims

1. A compressor (11) that compresses and discharges a refrigerant; a branching section (12a) that branches the flow of the refrigerant discharged from the compressor; a heating section (15) that heats an object to be heated using the refrigerant flowing out of one outlet of the branching section as a heat source; a low-temperature side pressure reduction section (19, 26, 27) that reduces the pressure of the refrigerant flowing out of the heating section; a bypass passage (13) that circulates the other of the refrigerant branched at the branching section; a bypass side pressure reduction section (14) that adjusts the flow rate of the refrigerant flowing through the bypass passage; a merging section (12b, 25) that merges the flow of the refrigerant flowing out of the bypass side pressure reduction section and the flow of the refrigerant flowing out of the low-temperature side pressure reduction section and flows them to the suction port side of the compressor; and a heat absorption section (20) that causes at least the refrigerant flowing out of the low-temperature side pressure reduction section to absorb heat from an object to be absorbed. and a control unit (70) that performs control to switch between a first heating mode in which all of the refrigerant discharged from the compressor is caused to flow into the heating unit via the branching unit, and the heat absorbed from the heat absorption object is pumped up by the heat absorption unit to heat the heating object, and a second heating mode in which a portion of the refrigerant discharged from the compressor is caused to flow into the bypass passage via the branching unit, the refrigerant flowing out of the bypass side pressure reduction unit is guided to the junction unit, and another portion of the refrigerant discharged from the compressor is caused to flow into the heating unit via the branching unit, and the refrigerant flowing out of the heating unit is joined at the junction unit with the flow of the refrigerant from the bypass side pressure reduction unit to be sucked into the compressor, wherein when switching from the first heating mode to the second heating mode, the control unit performs a limiting operation to limit an amount of heat radiation in the heating unit in the first heating mode to a low amount, and completes switching to the second heating mode after performing the limiting operation.

2. The heat pump cycle device of claim 1, wherein the heating section has a radiator (16) that radiates heat contained in the refrigerant that flows into the heating section, and a supply adjustment section (62, 64) that adjusts the supply amount of the object to be heated supplied to the radiator, and the limiting operation controls the operation of the supply adjustment section to limit the supply amount of the object to be heated to the radiator to a value lower than a predetermined reference amount.

3. A heat pump cycle device as described in claim 1, wherein the control unit terminates the restriction operation and releases the restriction on the amount of heat dissipation in the heating unit when the heating capacity in the heating unit exceeds a predetermined standard heating capacity (KPd) while the restriction operation is being executed.

4. A heat pump cycle device as described in claim 1, wherein the control unit terminates the restriction operation and releases the restriction on the amount of heat dissipation in the heating unit when the pressure of the refrigerant in the heat absorption unit exceeds a predetermined reference low pressure (KPs) while the restriction operation is being performed.

5. A heat pump cycle device as described in any one of claims 1 to 4, wherein when switching from the first heating mode to the second heating mode, the control unit executes a heat absorption amount securing operation in parallel with the limiting operation to secure the amount of heat absorption in the heat absorption section by using the heat of the refrigerant discharged from the compressor and the heat absorbed by the heat absorption section from the heat absorption object, and completes the switching to the second heating mode after executing the heat absorption amount securing operation and the limiting operation.

6. A compressor (11) that compresses and discharges a refrigerant, a branching section (12a) that branches the flow of the refrigerant discharged from the compressor, a heating section (15) that heats an object to be heated using the refrigerant flowing out from one outlet of the branching section as a heat source, a low-temperature side pressure reduction section (19, 26, 27) that reduces the pressure of the refrigerant flowing out from the heating section, a bypass passage (13) that circulates the other of the refrigerant branched at the branching section, a bypass side pressure reduction section (14) that adjusts the flow rate of the refrigerant flowing through the bypass passage, a merging section (12b, 25) that merges the flow of the refrigerant flowing out from the bypass side pressure reduction section and the flow of the refrigerant flowing out from the low-temperature side pressure reduction section and flows them out to the suction port side of the compressor, and a heat absorption section (20) that causes the refrigerant flowing out from at least the low-temperature side pressure reduction section to absorb heat from an object to be absorbed, a control unit (70) that performs control to switch between a first heating mode in which all of the refrigerant discharged from the compressor is caused to flow into the heating unit via the branching unit, and the heat absorbed from the heat absorption object is pumped up by the heat absorption unit to heat the heating object, and a second heating mode in which a part of the refrigerant discharged from the compressor is caused to flow into the bypass passage via the branching unit, the refrigerant flowing out from the bypass side pressure reduction unit is guided to the junction unit, and another part of the refrigerant discharged from the compressor is caused to flow into the heating unit via the branching unit, and the refrigerant flowing out from the heating unit is joined at the junction unit with the flow of the refrigerant from the bypass side pressure reduction unit to be sucked into the compressor, and the control unit When switching from the first heating mode to the second heating mode, a heat absorption amount securing operation is performed to secure the amount of heat absorption in the heat absorption section by using the heat of the refrigerant discharged from the compressor and the heat absorbed from the heat absorption object in the heat absorption section, and after performing the heat absorption amount securing operation, the heat pump cycle device completes switching to the second heating mode.

7. The heat pump cycle device according to claim 6, wherein the heat absorption amount securing operation, when operating in the first heating mode, continues to absorb heat from the heat absorption object in the heat absorption section, while at the same time causing a portion of the refrigerant discharged from the compressor to flow into the bypass passage via the branching section, and directing the refrigerant flowing out from the bypass side pressure reduction section to the junction section.

8. A heat pump cycle device as described in claim 6, wherein the control unit suppresses heat absorption in the heat absorption unit when the heat absorption amount securing operation is being performed and a heat absorption stop condition is satisfied in which the amount of heat absorbed by the refrigerant from the heat absorption object in the heat absorption unit is lower than a predetermined reference heat absorption amount (KTc).

9. A heat pump cycle device as described in claim 8, wherein when the heat absorption stop condition is satisfied while the heat absorption amount securing operation is being performed, the control unit reduces the amount of the heat absorption object supplied to the heat absorption section, thereby suppressing heat absorption in the heat absorption section.

10. A heat pump cycle device as described in claim 8, further comprising a refrigerant bypass flow path connected to guide the flow of the refrigerant flowing out from the heating section to the junction section, bypassing the heat absorption section (21), and when the heat absorption stop condition is satisfied while the heat absorption amount securing operation is being performed, the control section uses the refrigerant bypass flow path to stop the supply of the refrigerant to the heat absorption section (21), thereby suppressing heat absorption in the heat absorption section.

11. A heat pump cycle (10) having a compressor (11) that compresses and discharges a refrigerant, a heat medium refrigerant heat exchanger (17) that dissipates heat of the high-pressure refrigerant discharged from the compressor to a heat medium, a pressure reduction section (19) that reduces the pressure of the refrigerant flowing out of the heat medium refrigerant heat exchanger, and a chiller (21) that exchanges heat between the refrigerant reduced in pressure in the pressure reduction section and the heat medium, causing the refrigerant to absorb heat; a first circuit (41) configured to allow the heat medium flowing out of the heat medium refrigerant heat exchanger to circulate and including a heat medium radiator (43) that radiates heat possessed by the heat medium to a heating object; a second circuit (31) configured to allow the heat medium flowing through the chiller to circulate and including a heat medium heat absorber (33) that absorbs heat from a heat absorption object by heat exchange with the heat medium; a heat medium circuit (30) including a heat medium connection flow path (50) that connects between the first circuit and the second circuit so that the heat medium can flow in and out; and a flow rate adjustment unit (55) that adjusts a flow rate of the heat medium flowing in and out between the first circuit and the second circuit via the heat medium connection flow path; and an independent circulation heating mode in which heat derived from the heat absorption object is absorbed and pumped up from the heat medium circulating independently in the second circuit, and the heating object is heated by the heat medium radiator via the heat medium circulating independently in the first circuit; and a control unit (70) that performs control to switch to a circuit-linked heating mode in which a portion of the heat medium that has circulated through the heat medium refrigerant heat exchanger is circulated through the chiller via the heat medium connection flow path, and another portion of the heat medium that has circulated through the heat medium refrigerant heat exchanger is circulated through the first circuit via the heat medium radiator, and the heat object is heated by the heat medium radiator, wherein when switching from the independent circulation heating mode to the circuit-linked heating mode, the control unit performs a limiting operation to limit an amount of heat radiation in the heat medium radiator in the independent circulation heating mode to a low amount, and completes switching to the circuit-linked heating mode after performing the limiting operation.

12. A heat pump cycle apparatus as described in claim 11, further comprising a supply adjustment unit (62, 64) that adjusts the supply amount of the object to be heated supplied to the heat medium radiator, and the limiting operation controls the operation of the supply adjustment unit to limit the supply amount of the object to be heated to the heat medium radiator to be lower than a predetermined reference amount.

13. A heat pump cycle device as described in claim 11, wherein the control unit terminates the limiting operation and releases the restriction on the amount of heat dissipation in the heat medium radiator when the heating capacity for the heat medium circulating through the first circuit exceeds a predetermined standard (KPd) while the limiting operation is being executed.

14. A heat pump cycle device as described in claim 11, wherein the control unit terminates the limiting operation and releases the restriction on the amount of heat dissipation in the heat medium radiator when the pressure of the refrigerant in the chiller exceeds a predetermined reference low pressure (KPs) while the limiting operation is being performed.

15. A heat pump cycle device as described in any one of claims 11 to 14, wherein when switching from the independent circulation heating mode to the circuit-linked heating mode, the control unit executes a heat absorption amount securing operation in parallel with the limiting operation to secure the amount of heat absorption in the chiller by using the heat absorbed from the heat absorption object in the heat medium heat absorber and the heat of the heat medium led from the first circuit to the chiller via the heat medium connection flow path, and completes switching to the circuit-linked heating mode after executing the heat absorption amount securing operation and the limiting operation.

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