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

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.

Technical Field

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

Background Art

[0003] Conventionally, technologies have been developed for applying a heat pump cycle device to a vehicle air conditioner, and a heat pump heating mode has been realized in which a heating object is heated using heat absorbed from an external heat absorption source. Specifically, a vehicle air conditioner having a heat pump heating mode for performing heat pump heating with the blown air supplied to the vehicle compartment as the heating object is known.

[0004] The heating capacity in such a heat pump heating mode is affected by the amount of heat absorbed from the heat absorption source. Therefore, when the amount of heat that can be absorbed from the heat absorption source is lower than the required heating capacity, it is assumed that the heating object cannot be sufficiently heated. For example, when the outside air is used as the heat absorption source, sufficient heating capacity (i.e., heating capacity) could not be exhibited in an environment with low outside air temperature.

[0005] In a heat pump cycle device, in such a case, an operation mode is adopted in which a part of the heat of the high-pressure refrigerant discharged from the compressor is used to increase the work amount of the compressor, thereby enabling the heating capacity of the heating object to be exhibited. As a technology related to a heat pump cycle device having these two operation modes, the technology described in Patent Document 1 is known.

[0006] The vehicle air conditioning system described in 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 that increases the workload of the compressor itself by bypassing a portion of the refrigerant discharged from the compressor to the low-pressure side, thereby enabling the heating capacity of the object to be heated (i.e., the blown air). [Prior art documents] [Patent Documents]

[0007] [Patent Document 1] Japanese Patent Publication No. 2021-156567 [Overview of the project]

[0008] Here, if we simply switch from the heat pump heating mode to an operating mode that increases the workload of the compressor by utilizing a portion of the heat contained in the refrigerant discharged from the compressor to increase the heating capacity, it is expected that a decrease in the heating capacity of the object being heated will occur.

[0009] To explain using the heat pump heating mode and hot gas heating mode described in Patent Document 1 as examples, in the hot gas heating mode, the heating capacity of the object to be heated is determined by the amount of work done by the compressor. The amount of work done by the compressor is proportional to the refrigerant flow rate in the compressor, and the refrigerant flow rate in the compressor is proportional to the refrigerant suction density to the compressor. Therefore, in order to increase the heating capacity in the hot gas heating mode, it is important to increase the refrigerant suction density to the compressor, or in other words, it is necessary to increase the refrigerant suction pressure in the compressor.

[0010] On the other hand, in heat pump heating mode, the heating capacity of the object to be heated corresponds to the amount of heat absorbed in the heat absorber, and the amount of heat absorbed in 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 object to be heated. Therefore, in order to increase the heating capacity in 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 a standard determined by the temperature of the object to be heated.

[0011] Thus, in hot gas heating mode, the higher the low pressure in the cycle, the greater the heating capacity that can be secured, whereas in heat pump heating mode, the lower the low pressure in the cycle, the greater the heating capacity that can be secured.

[0012] When switching between the heat pump heating mode and the hot gas heating mode, which have these conflicting 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's low pressure is low, it will be insufficient for the heating capacity required by heat gas heating, and the heating capacity will fluctuate with the mode switch. Furthermore, in the hot gas heating mode transitioned under these conditions, it is necessary to increase the low pressure to compensate for the deficiency, and it is anticipated 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, this 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 a portion of the heat contained in the high-pressure refrigerant discharged from the compressor to exert heating capacity.

[0014] A heat pump cycle device according to a first aspect of the present disclosure includes a compressor, a branching section, a heating section, a low-temperature side pressure reduction section, a bypass passage, a bypass side pressure reduction section, a confluence 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 the object to be heated using the refrigerant flowing out from one of the outlets 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 allows the other branch of the refrigerant that was branched off at the branching section to flow through. The bypass side pressure reduction section reduces the pressure of the refrigerant flowing through the bypass passage. The merging 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 discharges it towards the compressor's intake. The heat absorption section allows the heat contained in the object to be absorbed to be absorbed by the refrigerant flowing out, at least from the low-temperature side pressure reduction section.

[0016] The control unit controls the switching between the first heating mode and the second heating mode. In the first heating mode, all of the refrigerant discharged from the compressor flows into the heating section via the branching section, and the heat absorbed from the object to be heated in the heat absorption section is drawn up 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 branching section, and the refrigerant that flows out from the bypass-side pressure reduction section is guided to the confluence section. At the same time, in the second heating mode, the remaining portion of the refrigerant discharged from the compressor flows into the heating section via the branching section, and the refrigerant that flows out from the heating section is combined with the flow of refrigerant from the bypass-side pressure reduction section at the confluence section and drawn into the compressor.

[0017] Then, when the control unit switches from the first heating mode to the second heating mode, it performs a limiting operation to reduce the amount of heat dissipated in the heating section of the first heating mode, and after performing the limiting operation, it completes the switch to the second heating mode.

[0018] Therefore, according to the heat pump cycle device of the first embodiment, a limiting operation is performed when switching from the first heating mode to the second heating mode, and the amount of heat dissipated from the refrigerant in the heating section is suppressed, thereby increasing the amount of heat contained in the refrigerant immediately before switching to the second heating mode. As a result, the heat pump cycle device of the first embodiment can keep the difference between the heating capacity in the first heating mode and the heating capacity in the second heating mode small, and can suppress fluctuations in heating capacity.

[0019] Furthermore, the heat pump cycle device according to a second aspect of this disclosure includes a compressor, a branching section, a heating section, a low-temperature side pressure reduction section, a bypass passage, a bypass side pressure reduction 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 the object to be heated using the refrigerant flowing out from one of the outlets 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 allows the other branch of the refrigerant that was branched off at the branching section to flow through. The bypass side pressure reduction section reduces the pressure of the refrigerant flowing through the bypass passage. The merging 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 discharges it towards the compressor's intake. The heat absorption section allows the heat contained in the object to be absorbed to be absorbed by the refrigerant flowing out from at least the low-temperature side pressure reduction section.

[0021] The control unit controls the switching between the first heating mode and the second heating mode. In the first heating mode, all of the refrigerant discharged from the compressor flows into the heating section via the branching section, and heat absorbed from the object to be heated is drawn up in the heat absorption section 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 branching section, and the refrigerant that has flowed out from the bypass-side pressure reduction section is guided to the confluence section. At the same time, in the second heating mode, the remaining portion of the refrigerant discharged from the compressor flows into the heating section via the branching section, and the refrigerant that has flowed out from the heating section is combined with the flow of refrigerant from the bypass-side pressure reduction section at the confluence section and drawn into the compressor.

[0022] Then, when the control unit switches from the first heating mode to the second heating mode, it performs a heat absorption amount securing operation to ensure the amount of heat absorbed in the heat absorption section by using the heat contained in the refrigerant discharged from the compressor and the heat absorbed from the object to be heated in the heat absorption section. After performing the heat absorption amount securing operation, the control unit completes the switch to the second heating mode.

[0023] Therefore, according to the heat pump cycle device according to the second aspect, when switching from the first heating mode to the second heating mode, an endothermic amount ensuring operation is executed to ensure the endothermic amount for the refrigerant, thereby increasing the amount of heat possessed by the refrigerant immediately before switching to the second heating mode. As a result, the heat pump cycle device according to the second aspect can suppress the difference between the heating capacity in the first heating mode and the heating capacity in the second heating mode to a small level and suppress fluctuations in the heating capacity.

[0024] And the heat pump cycle device according to the 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 decompression unit, and a chiller. The compressor compresses and discharges the refrigerant. The heat medium-refrigerant heat exchanger dissipates the heat of the high-pressure refrigerant discharged from the compressor to the heat medium. The decompression unit decompresses the refrigerant flowing out from the heat medium-refrigerant heat exchanger. The chiller exchanges heat between the refrigerant decompressed by the decompression unit and the heat medium to cause the refrigerant to absorb heat.

[0025] The heat medium circuit includes a first circuit, a second circuit, a heat medium connection flow path, and a flow rate adjustment unit. The first circuit is configured such that the heat medium flowing out from the heat medium-refrigerant heat exchanger can circulate, and includes a heat medium radiator that dissipates the heat possessed by the heat medium to the object to be heated. The second circuit is configured such that the heat medium flowing through the chiller can circulate, and has a heat medium absorber that absorbs heat from the heat absorption object by heat exchange with the heat medium. The heat medium connection flow path is connected between the first circuit and the second circuit so that the heat medium can flow in and out. The flow rate adjustment unit adjusts the flow rate of the heat medium flowing in and out between the first circuit and the second circuit through the heat medium connection flow path.

[0026] The control unit performs control to switch between an independent circulation heating mode and a circuit cooperation heating mode. In the independent circulation heating mode, heat from the heat absorption object is absorbed and pumped up from the heat medium that circulates through the second circuit independently, and the heating object is heated by the heat medium radiator through the heat medium that circulates through the first circuit independently. In the circuit cooperation heating mode, a part of the heat medium that has passed through the heat medium refrigerant heat exchanger is circulated through the chiller via the heat medium connection flow path, and another part of the heat medium that has passed through the heat medium refrigerant heat exchanger is circulated through the first circuit via the heat medium radiator, and the heating object is heated by the heat medium radiator.

[0027] When the control unit switches from the independent circulation heating mode to the circuit cooperation heating mode, it executes a limiting operation to limit the heat dissipation amount in the heat medium radiator of the independent circulation heating mode, and after executing the limiting operation, it completes the switch to the circuit cooperation heating mode.

[0028] Therefore, according to the heat pump cycle device according to the third aspect, by executing the limiting operation when switching from the independent circulation heating mode to the circuit cooperation heating mode and suppressing the heat dissipation amount in the heat medium radiator, the heat amount of the refrigerant immediately before switching to the circuit cooperation heating mode can be increased. As a result, the heat pump cycle device according to the third aspect can suppress the difference between the heating capacity in the independent circulation heating mode and the heating capacity in the circuit cooperation heating mode, and can suppress the fluctuation of the heating capacity.

Brief Description of the Drawings

[0029] The above objects, other objects, features, and advantages of the present disclosure will become more apparent from the following detailed description with reference to the accompanying drawings. [Figure 1] It is a configuration diagram of a heat pump cycle device according to the first embodiment. [Figure 2] It is a configuration diagram of an indoor air conditioning unit according to the first embodiment. [Figure 3] It is a block diagram showing the control system of the heat pump cycle device according to the first embodiment. [Figure 4]This is a Mollier diagram of the heat pump heating operation in the heat pump cycle device according to the first embodiment. [Figure 5] This is a Mollier diagram of a heat pump cycle device according to the first embodiment during hot gas heating operation. [Figure 6] This is an explanatory diagram showing an example of switching control in a heat pump cycle device according to the first embodiment. [Figure 7] This is a diagram showing the configuration of a heat pump cycle device according to the second embodiment. [Figure 8] This is an explanatory diagram showing the first state in the switching control of the heat pump cycle device according to the second embodiment. [Figure 9] This is an explanatory diagram showing the second state in the switching control of the heat pump cycle device according to the second embodiment. [Figure 10] This is a diagram showing the configuration of a heat pump cycle device according to the third embodiment. [Figure 11] This is an explanatory diagram showing the first state in the switching control of the heat pump cycle device according to the third embodiment. [Figure 12] This is an explanatory diagram showing the second state in the switching control of the heat pump cycle according to the third embodiment. [Figure 13] This is a diagram showing the configuration of a heat pump cycle device according to the fourth embodiment. [Figure 14] This is an explanatory diagram illustrating the operation of the heat pump cycle device according to the fourth embodiment during independent circulation heating operation. [Figure 15] This is an explanatory diagram regarding the operation of the heat pump cycle device during circuit-linked heating operation according to the fourth embodiment. [Figure 16] This is an explanatory diagram showing an example of switching control of a heat pump cycle device according to the fourth embodiment. [Modes for carrying out the invention]

[0030] Several embodiments for carrying out this disclosure are described below with reference to the drawings. In each embodiment, parts corresponding to matters described in a prior embodiment may be denoted by the same reference numerals, and redundant descriptions may be omitted. If only a part of the configuration is described in each embodiment, other parts of the configuration can be applied to other embodiments described in advance. Not only can parts that are explicitly shown to be combinable in each embodiment be combined, but embodiments can also be partially combined even if not explicitly shown, as long as there is no particular impediment to the combination.

[0031] (First Embodiment) A first embodiment of the heat pump cycle device in this disclosure will be described with reference to Figures 1 to 6. In the first embodiment, the heat pump cycle device according to this disclosure is applied to a vehicle air conditioning system 1 installed in an electric vehicle. An electric vehicle is a vehicle that obtains driving force for propulsion from an electric motor.

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

[0033] Next, the general configuration of the vehicle air conditioning system 1 according to the first embodiment will be described. First, the configuration of the heat pump cycle 10 in the vehicle air conditioning system 1 according to the first embodiment will be described with reference to Figure 1.

[0034] The heat pump cycle 10 of the vehicle air conditioning system 1 according to the first embodiment is a vapor compression type refrigeration cycle that adjusts the temperature of the air supplied to the vehicle interior and the heat transfer medium circulating in the heat transfer medium circuit 30.

[0035] The heat pump cycle 10 is configured to allow switching of the refrigerant circuit according to various operating modes in order to provide air conditioning for the vehicle interior. The heat pump cycle 10 uses an HFO-type 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 refrigeration oil for lubricating the compressor 11. The refrigeration oil is PAG oil (i.e., polyalkylene glycol oil) or POE (i.e., polyol ester) which is compatible with the liquid phase refrigerant. A portion of the refrigeration oil circulates with the refrigerant in the heat pump cycle 10.

[0037] As shown in Figure 1, the 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 in the heat pump cycle 10 draws in refrigerant, compresses it, and discharges it. The compressor 11 is an electric compressor in which a fixed-capacity compression mechanism with a fixed discharge capacity is rotationally driven by an electric motor. The refrigerant discharge capacity (i.e., rotational speed) of the compressor 11 is controlled by a control signal output from the control device 70.

[0039] The compressor 11 is located in the drive unit compartment, which is formed on the front side of the passenger compartment. The drive unit compartment is a space in which at least some of the equipment used for generating and adjusting the driving force for vehicle operation (for example, a motor generator which becomes an electric motor for driving) is located.

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

[0041] Furthermore, the heat pump cycle 10 according to the first embodiment has a junction section 12b formed in the shape of a three-way joint. The basic configuration of the junction section 12b is the same as that of the branch section 12a, having three inlet and outlet ports that communicate with each other.

[0042] Specifically, when one of the three inlet / outlet ports in a three-way joint is used as an inlet and the remaining two are used as outlets, it functions as a branching section that divides the flow of refrigerant. Also, when two of the three inlet / outlet ports are used as inlets and the remaining one is used as an outlet, it functions as a confluence section that merges the flows of refrigerant. Branching section 12a is a branching section that divides the flow of discharged refrigerant discharged from the compressor 11.

[0043] One outlet of the branch section 12a is connected to the inlet side of the indoor condenser 16 that constitutes the heating section 15. The other outlet of the branch section 12a is connected to one inlet side of the confluence section 12b, which is formed in the shape of a three-way joint, via the bypass passage 13.

[0044] The bypass passage 13 is a refrigerant passage that guides the flow of high-pressure refrigerant discharged from the compressor 11, specifically the flow that flows out from the other outlet at the branch section 12a, to one of the inlets at the confluence section 12b. As shown in Figure 1, a bypass-side expansion valve 14 is located in the bypass passage 13.

[0045] The bypass-side expansion valve 14 is a pressure reducing unit on the bypass passage 13 side that reduces the pressure of the high-pressure refrigerant flowing out from the other outlet of the branch section 12a (i.e., the other discharged refrigerant branched off at the branch section 12a) during various operating modes, such as the hot gas heating mode. The bypass-side expansion valve 14 can also be described as a flow rate adjustment unit 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 electrically operated variable throttling mechanism having a valve body that changes the throttling opening and an electric actuator (specifically, a stepping motor) as a drive unit that displaces the valve body. The operation of the bypass-side expansion valve 14 is controlled by control pulses output from the control device 70.

[0047] The bypass-side expansion valve 14 has a fully open function that allows it to function as a simple refrigerant passage without exerting much refrigerant pressure reduction or flow rate adjustment effect when the throttle opening is fully open. Furthermore, the bypass-side expansion valve 14 has a fully closed function that blocks the refrigerant passage when the throttle opening is fully closed.

[0048] As described above, an indoor condenser 16 is connected to one of the outlets in the branch section 12a. The indoor condenser 16 is a heat exchange unit for heat dissipation that exchanges heat between the high-pressure refrigerant discharged from the compressor 11 and the blown air supplied to the vehicle interior, thereby releasing the heat contained in the high-pressure refrigerant into the blown air. The indoor condenser 16 constitutes a heating unit 15 that heats the blown air, which is the object to be heated, using the refrigerant discharged from the compressor 11 as a heat source.

[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 gaseous and liquid phases of the refrigerant flowing out from the condenser (i.e., the indoor condenser 16) in the heat pump cycle 10, allowing the liquid phase refrigerant to flow downstream, and also stores excess refrigerant from the cycle.

[0050] A low-temperature expansion valve 19 is connected to the outlet side of the receiver 18. The low-temperature expansion valve 19 is a pressure reducing unit that reduces the pressure of the refrigerant flowing into the refrigerant passage 21a of the chiller 21, which constitutes the heat absorption unit 20, when the refrigerant absorbs heat in the heat absorption unit 20. The low-temperature expansion valve 19 can also be described as a flow rate adjustment unit on the chiller side that adjusts the flow rate (mass flow rate) of the refrigerant flowing into the chiller 21.

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

[0052] Furthermore, a chiller 21, which constitutes the heat absorption section 20, is connected to the outlet side of the low-temperature side expansion valve 19. The heat absorption section 20 is the part where heat is absorbed from the low-pressure refrigerant that has been reduced in pressure by the low-temperature side expansion valve 19, and in the first embodiment, it is composed of a heat transfer medium circuit 30 and a chiller 21.

[0053] The chiller 21 has a refrigerant passage 21a through which low-pressure refrigerant, which has been reduced in pressure by the low-temperature side expansion valve 19, flows, and a heat medium passage 21b through which heat medium circulating in the heat medium circuit 30 flows. The chiller 21 is a low-temperature side heat medium heat exchange section that exchanges heat between the low-pressure refrigerant flowing through the refrigerant passage 21a and the heat medium flowing through the heat medium passage 21b. In the chiller 21, the heat medium is cooled by evaporating the low-pressure refrigerant to exert an endothermic effect.

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

[0055] Furthermore, the outlet side of the confluence section 12b is connected to the suction side of the compressor 11. Therefore, the confluence section 12b can combine the flow of refrigerant that has flowed out of the refrigerant passage 21a of the chiller 21 and the flow of refrigerant that has flowed through the bypass passage 13 and guide them to the suction side of the compressor 11.

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

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

[0058] The low-temperature pump 32 is a heat transfer unit that draws in the heat transfer medium flowing out from the heat transfer medium three-way valve 34 and pressurizes it to the outside air heat exchanger 33. The low-temperature pump 32 is an electric water pump whose rotational speed (i.e., pumping capacity) is controlled by a control voltage output from the control device 70. Therefore, in the first embodiment, the circulation of the heat transfer medium within the low-temperature circuit 31 can be achieved by driving the low-temperature pump 32.

[0059] An outside air heat exchanger 33 is connected to the discharge port side of the low-temperature pump 32. The outside air heat exchanger 33 is located outside the vehicle compartment and exchanges heat between the heat transfer medium, which is cooled by the chiller 21 and circulates in the low-temperature circuit 31, and the outside air outside the vehicle compartment. The outside air heat exchanger 33 constitutes part of the heat absorption section that absorbs heat from the outside air to the low-pressure refrigerant via the heat transfer medium.

[0060] A three-way valve 34 for the heat transfer medium is connected to the heat transfer medium outlet side of the outside air heat exchanger 33. The three-way valve 34 is an electrically operated three-way flow control valve with three inlet and outlet ports, and is configured to allow continuous adjustment of the passage area ratio of each outlet. The operation of the three-way valve 34 is controlled by a control signal output from the control device 70.

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

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

[0063] Furthermore, a heat transfer medium bypass channel 36 is connected to the other inlet / outlet of the bypass connection section 35, and the suction port side of the low-temperature pump 32 is connected to the other inlet / outlet of the heat transfer medium bypass channel 36.

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

[0065] Next, the configuration of the interior air conditioning unit 60, which constitutes the vehicle air conditioning system 1, will be explained with reference to Figure 2. The interior air conditioning unit 60 is a unit in the vehicle air conditioning system 1 that blows air whose temperature has been adjusted by the heat pump cycle 10 to an appropriate location in the vehicle interior. The interior air conditioning unit 60 is located inside the instrument panel at the very front of the vehicle interior.

[0066] The interior air conditioning unit 60 according to the first embodiment is configured by housing 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 its outer shell. The air conditioning case 61 forms an air passage for the blown air supplied to the vehicle interior. The air conditioning case 61 is molded from a resin (specifically, polypropylene) that has a certain degree of elasticity and excellent strength.

[0067] As shown in Figure 2, an internal / external air switching device 63 is located at the upstream end of the airflow path of the air conditioning case 61. The internal / external air switching device 63 switches between introducing internal air (inside the vehicle) and outside air (outside the vehicle) into the air conditioning case 61.

[0068] The internal / external air switching device 63 continuously adjusts the opening area of ​​the internal air inlet for introducing internal air and the external air inlet for introducing external air into the air conditioning case 61 using the internal / external air switching door, thereby changing the ratio of the internal air intake volume to the external air intake volume. The internal / external air switching door is driven by an electric actuator for the internal / external air switching door. The operation of this electric actuator is controlled by a control signal output from the control device 70.

[0069] An indoor blower 62 is positioned downstream of the airflow from the indoor / outdoor air switching device 63. The indoor blower 62 is an electric blower in which a centrifugal multi-blade fan is driven by an electric motor. The indoor blower 62 blows the air drawn in via the indoor / outdoor air switching device 63 into the vehicle interior. The rotational speed (i.e., blowing capacity) of the indoor blower 62 is controlled by a control voltage output from the control device 70. Since the indoor blower 62 can adjust the airflow rate of the blown air that is subject to temperature control, it 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 airflow of the indoor blower 62 downstream of the airflow. The cooler core 33a constitutes a cooling heat exchanger that cools the airflow by exchanging heat between a medium cooled by a cooling source (e.g., a heat transfer medium or refrigerant) and the airflow flowing through the air conditioning case 61.

[0071] As shown in Figure 2, the cooler core 33a is positioned upstream of the indoor condenser 16 in the air conditioning case 61 of the indoor air conditioning unit 60. Therefore, in the indoor air conditioning unit 60 of the vehicle air conditioning system 1, at least a portion of the air that has passed through the cooler core 33a can be heated by the indoor condenser 16.

[0072] Furthermore, a cold air bypass passage 65 is formed inside the air conditioning case 61. The cold air bypass passage 65 is an air passage that directs the air that has passed through the cooler core 33a to the downstream side, bypassing the indoor condenser 16.

[0073] An air mix door 64 is positioned downstream of the airflow of the cooler core 33a and upstream of the airflow of the indoor condenser 16. The air mix door 64 adjusts the ratio of the airflow that passes through the indoor condenser 16 and the airflow that passes through the cold air bypass passage 65 from the airflow that has passed through the cooler core 33a.

[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, through its operation control, adjusts the amount of air supplied to the indoor condenser 16 and the like, which is subject to temperature control, and therefore corresponds to an example of a supply adjustment unit.

[0075] Furthermore, a mixing space is provided downstream of the airflow from the indoor condenser 16. In the mixing space, the air heated by the indoor condenser 16 is mixed with the air that has passed through the cold air bypass passage 65 and has not been heated by the indoor condenser 16.

[0076] Furthermore, at the downstream end of the airflow path of the air conditioning case 61, there is an opening for blowing the mixed air (conditioned air) into the vehicle interior. This opening includes a face opening, a foot opening, and a defroster opening (none of which are shown).

[0077] The face opening is an opening that blows conditioned air towards the upper body of the occupants inside the vehicle. The foot opening is an opening that blows conditioned air towards the occupants' feet. The defroster opening is an opening that blows conditioned air towards the inner surface of the front window glass of the vehicle.

[0078] These face openings, foot openings, and defroster openings are connected to face outlets, foot outlets, and defroster outlets (none of which are shown) located inside the vehicle cabin, via ducts that form air passages.

[0079] Therefore, the air mix door 64 adjusts the ratio of the airflow rate between the airflow rate passing through the interior condenser 16 and the airflow rate passing through the cold air bypass passage 65, thereby adjusting the temperature of the conditioned air mixed in the mixing space. This also adjusts the temperature of the air blown into the passenger compartment from each outlet (conditioned air).

[0080] Furthermore, a face door, a foot door, and a defroster door (none of which are shown) are positioned upstream of the airflow through the face opening, foot opening, and defroster opening, 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] These face doors, foot doors, and defroster doors constitute a blowing mode switching device that switches the air outlets from which conditioned air is blown. The face doors, foot doors, and defroster doors are connected via a linkage mechanism or the like to an electric actuator for driving the air outlet mode door, and are rotated in conjunction with it. 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 conditioning system 1 will be explained using Figure 3. The control device 70 consists of a well-known microcomputer including a CPU, ROM, and RAM, and its peripheral circuits. The control device 70 performs various calculations and processes based on the 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 is 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 transfer fluid three-way valve 34, an indoor blower 62, an indoor / outdoor air switching device 63, an air mix door 64, and the like.

[0084] As shown in Figure 3, various control sensors are connected to the input side of the control device 70. These control sensors include an indoor air temperature sensor 72a, an outdoor air temperature sensor 72b, and a solar radiation sensor 72c. Additionally, these 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. Furthermore, these control sensors include a low-temperature heat transfer medium temperature sensor 73a and an air conditioning air temperature sensor 73b.

[0085] The interior air temperature sensor 72a is an interior air temperature detection unit that detects the interior air temperature Tr, which is the temperature inside the vehicle. The exterior air temperature sensor 72b is an exterior air temperature detection unit that detects the exterior air temperature Tam, which is the temperature outside the vehicle. The solar radiation sensor 72c is a solar radiation detection unit that detects the amount of solar radiation As that is irradiated into the vehicle.

[0086] The high-pressure sensor 72d is a high-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 sensor 72e is a low-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 located, 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 located, for example, on the outlet side of the refrigerant passage 21a in the chiller 21.

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

[0088] Furthermore, the control device 70 is connected to an operation panel 71 located near the instrument panel at the front of the vehicle interior. The control device 70 receives operation signals from various operation switches provided on this operation panel 71.

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

[0090] The air conditioning switch is an operating switch that requests the cooling of the blown air by the cooler core 33a. The airflow setting switch is an operating switch that is operated when manually setting the airflow of the interior blower 62. The temperature setting switch is an operating switch that sets the target temperature Tset inside the vehicle.

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

[0092] For example, the configuration of the control device 70 that performs 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 to the hot gas heating mode, as described later, corresponds to the switching control execution unit 70a.

[0093] Furthermore, within the control device 70, the configuration that controls the limiting operation to restrict the amount of heat emitted by the heating unit 15 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 a heat absorption amount securing operation to ensure the amount of heat absorbed by the heat absorption unit 20 in the switching control when switching from the heat pump heating mode to the hot gas heating mode corresponds to the heat absorption amount securing control unit 70c.

[0095] Here, the operating modes of the vehicle air conditioning system 1, which heats the blown air that is the object to be heated, include a heat pump heating mode and a hot gas heating mode. First, the heat pump heating mode in the vehicle air conditioning system 1 will be explained with reference to Figure 4.

[0096] In the heat pump heating mode according to the first embodiment, heat absorbed from a heat absorption source (air outside the vehicle) is drawn up via the low-temperature side circuit 31 and released into the blown air by the indoor condenser 16 that constitutes the heating unit 15, thereby heating the blown air. Therefore, the heat pump heating mode corresponds to an example of the first heating mode, as it draws up heat absorbed from a heat absorption source and corresponds to heating the blown air.

[0097] In the heat pump heating mode of the first embodiment, the control device 70 closes the bypass-side expansion valve 14 completely and throttles the low-temperature-side expansion valve 19. As a result, in the heat pump cycle 10 of the heat pump heating mode, the refrigerant is switched to a refrigerant circuit that circulates in the following order: compressor 11, branch section 12a, indoor condenser 16, receiver 18, low-temperature-side expansion valve 19, chiller 21, junction section 12b, and compressor 11.

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

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

[0100] With respect to the heat transfer medium circuit 30, the control device 70 determines the pumping capacity of the low-temperature side pump 32 and the ratio of the opening areas of the three outlets in the heat transfer medium three-way valve 34 so as to ensure the amount of heat absorbed necessary to achieve the target discharge temperature.

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

[0102] Therefore, in the heat pump cycle 10 of the heat pump heating mode, the state of the refrigerant changes as shown in the Mollier diagram in Figure 4. That is, the discharged refrigerant (point A1 in Figure 4) discharged from the compressor 11 flows into the indoor condenser 16 via the branching section 12a. The refrigerant that flows into the indoor condenser 16 condenses inside the indoor air conditioning unit 60 by releasing heat into the blown air, which is the object to be heated (from point A1 to point A2 in Figure 4). As a result, the blown air, which is the object to be heated, is heated, and heating of the vehicle interior is achieved.

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

[0104] In other words, in the heat pump cycle 10 of the heat pump heating mode, a vapor compression type 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 in the vehicle air conditioning system 1 will be described with reference to Figure 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 to the low-pressure side via the bypass passage 13, thereby improving the heating capacity of the object to be heated by utilizing the work of the compressor 11. The hot gas heating mode corresponds to an example of the second heating mode.

[0106] Furthermore, in hot gas heating mode, the object to be heated is heated using the work of the compressor 11 without utilizing the heat absorption source (i.e., the low-temperature circuit 31 and the outdoor air). Therefore, even if the amount of heat absorbed from the heat absorption source cannot be secured, the heating capacity can be improved.

[0107] In the heat pump cycle 10 of the hot gas heating mode according to the first embodiment, the control device 70 throttles the bypass-side expansion valve 14 and the low-temperature-side expansion valve 19. As a result, in the hot gas heating mode, a portion of the refrigerant discharged from the compressor 11 circulates in the following order: compressor 11, branch section 12a, indoor condenser 16, receiver 18, low-temperature-side expansion valve 19, chiller 21, junction section 12b, and compressor 11. At the same time, another portion of the refrigerant discharged from the compressor 11 circulates in the following order: compressor 11, branch section 12a, bypass passage 13, bypass-side expansion valve 14, junction section 12b, and compressor 11. In other words, in the hot gas heating mode, the refrigerant circuit is switched to one in which a path through which the refrigerant circulates via the indoor condenser 16 and a path through which the refrigerant circulates via the bypass passage 13 coexist.

[0108] Here, 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), to approach a constant pressure is effective in stabilizing the discharge flow rate Gr (mass flow rate) of the compressor 11.

[0109] More specifically, by using a saturated gaseous refrigerant at a constant low pressure Ps, the density of the suction refrigerant becomes constant. Therefore, by controlling the low pressure Ps to approach a constant pressure, it becomes easier to stabilize the discharge flow rate Gr of the compressor 11 at the same rotational speed.

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

[0111] In the hot gas heating mode, the heat transfer medium circuit 30 stops the low-temperature pump 32. In the hot gas heating mode, the indoor air conditioning unit 60 controls the operation of the indoor fan 62, the indoor / outdoor air switching device 63, and the air mix door 64. In the hot gas heating mode, the opening of the air mix door 64 is often controlled so that almost all of the air blown from the indoor fan 62 passes through the indoor condenser 16.

[0112] Therefore, in the heat pump cycle 10 of the hot gas heating mode according to the first embodiment, the state of the refrigerant changes as shown in the Mollier diagram in Figure 5.

[0113] First, the flow of the discharged refrigerant (point B1 in Figure 5) discharged from the compressor 11 is branched at the branching section 12a. One of the refrigerants branched at the branching section 12a flows into the indoor condenser 16 which constitutes the heating section 15, and releases heat into the blown air within the indoor air conditioning unit 60 (from point B1 to point B2 in Figure 5). As a result, the blown air, which is the object to be heated, is heated, and heating of the vehicle interior can be achieved.

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

[0115] Furthermore, the other refrigerant branched off at branch section 12a flows into the bypass passage 13. The refrigerant flowing into the bypass passage 13 is depressurized by the bypass-side expansion valve 14 (from point B1 to point B5 in Figure 5). The refrigerant depressurized by the bypass-side expansion valve 14 flows into one of the inlets of the confluence section 12b. The refrigerant flowing out from the chiller 21 and the refrigerant flowing out from the bypass-side expansion valve 14 merge and mix at the three-way joint-shaped confluence section 12b (point B5 in Figure 5), and are then drawn into the compressor 11.

[0116] In the hot gas heating mode heat pump cycle 10, the refrigerant with a low enthalpy (point B3 in Figure 5) that flows out from the chiller 21 and the refrigerant with a high enthalpy (point B4 in Figure 5) that flows out from the bypass passage 13 are mixed at the confluence section 12b. In other words, in the hot gas heating mode heat pump cycle 10, refrigerants with different enthalpy properties are mixed and drawn into the compressor 11.

[0117] Here, the hot gas heating mode is an operating mode that is executed when the amount of heat absorbed by the heat absorption section 20 is low, such as when the outside temperature Tam is extremely low. For this reason, when the refrigerant that has flowed out from the indoor condenser 16 flows through the heat absorption section 20, there is a possibility that the heat contained in the refrigerant will be released to the outside. If the heat contained in the refrigerant is released to the outside, the amount of heat that the refrigerant releases to the blown air from 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 transfer medium that is subject to heat exchange with the refrigerant flowing out from the bypass passage 13 is stopped, so that the heat contained in the refrigerant discharged from the compressor 11 can be maintained as much as possible.

[0119] Furthermore, in hot gas heating mode, the throttle opening of the low-temperature side expansion valve 19 is controlled so that the superheat level SH of the intake refrigerant approaches the reference superheat level KSH. This allows the intake refrigerant (point B5 in Figure 5) to be in a gaseous phase with a superheat level, even if the amount of heat released from the discharged refrigerant to the supplied air in the indoor condenser 16 is increased by increasing the refrigerant discharge capacity of the compressor 11.

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

[0121] In the heat pump heating mode of the vehicle air conditioning system 1, as described above, the heat absorbed by the heat absorption section 20 is pumped up and used to heat the object to be heated (blown air) in the heating section 15. Therefore, the heating capacity in the heat pump heating mode is strongly correlated with the amount of heat absorbed by the heat absorption section 20, and the greater the amount of heat absorbed, the greater the heating capacity.

[0122] The amount of heat absorbed in the heat absorption section 20 is affected by the temperature of the object being heated and the temperature or pressure of the low-pressure refrigerant in the heat pump cycle 10. In other words, in order to ensure sufficient heat absorption in the heat absorption section 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 object being heated in the heat absorption section 20 (e.g., heat transfer medium or air).

[0123] Furthermore, since the heating capacity in heat pump heating mode is strongly influenced by the amount of heat absorbed by the heat absorption section 20, depending on the state of the heat absorption section 20, it is conceivable that the required heating capacity may not be achieved as the heating capacity of the object to be heated. For example, if the heat absorption section 20 is configured to absorb heat from the air, if the air temperature is too low, it may not be possible to secure a sufficient amount of heat absorbed, resulting in insufficient heating capacity in heat pump heating mode.

[0124] In this respect, in the hot gas heating mode, the heating capacity is determined by the amount of work done by 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 amount of work done by 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 drawn 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, or in other words, to increase the suction pressure of the refrigerant in the compressor 11.

[0126] Thus, in the heat pump heating mode, a lower low pressure of the refrigerant in the heat pump cycle 10 ensures a greater heating capacity for the object being heated. On the other hand, in the hot gas heating mode, a higher low pressure of the refrigerant in the heat pump cycle 10 ensures a greater heating capacity for the object being heated.

[0127] In other words, the heat pump heating mode and the hot gas heating mode have conflicting characteristics in terms 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.

[0128] Therefore, when switching from heat pump heating mode to hot gas heating mode, fluctuations in heating capacity may occur due to conflicting characteristics regarding 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] To explain in more detail, 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 heat pump heating mode in order to achieve greater heating capacity.

[0130] When the system switches to hot gas heating mode while the low pressure of the refrigerant in the heat pump cycle 10 is low, the refrigerant intake density in the compressor 11 is low, resulting in a reduced workload for the compressor 11. In other words, switching to hot gas heating mode while the low pressure is low makes it impossible to secure the necessary heating capacity in hot gas heating mode, and thus it is not possible to guarantee the same heating capacity as the heat pump heating mode before the switch. As a result, the heating capacity of the blown air decreases, which is expected to lower the outlet temperature of the conditioned air supplied to the vehicle interior, thereby reducing the comfort of the occupants inside the vehicle.

[0131] Subsequently, when the system switches to hot gas heating mode, the low pressure of the refrigerant in the heat pump cycle 10 is increased to ensure the required heating capacity. By increasing the low pressure of the refrigerant in the heat pump cycle 10, the heating capacity of the object being heated is increased, and the outlet temperature of the conditioned air can be raised back to the state before the switch.

[0132] However, from the moment of switching from heat pump heating mode to hot gas heating mode until the heating capacity in hot gas heating mode is increased to the level before the switch, time is required to increase the low pressure in the heat pump cycle 10. As a result, the temperature of the air-conditioned air supplied to the passenger compartment changes with the switch in operating mode, resulting in a period of reduced passenger comfort.

[0133] In the first embodiment, the vehicle air conditioning system 1 performs switching control to suppress fluctuations in the heating capacity of the object to be heated caused by the difference in 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 heating capacity during mode switching and to make the fluctuations shorter in duration, it is desirable to quickly achieve a transition from a low low pressure state required in the heat pump heating mode to a high low pressure state required in the hot gas heating mode.

[0135] In order to increase the low pressure of the refrigerant in the heat pump cycle 10, it is necessary to increase the amount of heat contained in the refrigerant. Therefore, one possible operation in the switching control to increase the low pressure of the heat pump cycle 10 and suppress fluctuations in heating capacity is to reduce the amount of heat dissipated on the high-pressure side of the heat pump cycle 10.

[0136] This reduces the amount of heat dissipated on the high-pressure side of the heat pump cycle 10, allowing the refrigerant discharged from the compressor 11 to retain its heat, thereby increasing the low-pressure level in the heat pump cycle 10. This allows the low-pressure level of the heat pump cycle 10 to be quickly raised to the desired level, and enables the rapid elimination of fluctuations in heating capacity associated with switching operating modes. Hereinafter, the operation that reduces the amount of heat dissipated on the high-pressure side of the heat pump cycle 10 during operating mode switching control will be referred to as the limiting operation.

[0137] Furthermore, as one of the operations in the switching control to suppress fluctuations in heating capacity by increasing the low pressure of the heat pump cycle 10, an operation to maintain the amount of heat absorbed on the low-pressure side of the heat pump cycle 10 as much as possible can be considered.

[0138] As described above, in the heat pump heating mode before switching, heat is absorbed in the heat absorption section 20 on the low-pressure side of the heat pump cycle 10 via the heat transfer medium in the heat transfer medium circuit 30. The amount of heat absorbed in the heat absorption section 20 constitutes the amount of heat in the refrigerant flowing on the low-pressure side. In this state, for example, if the low-temperature pump 32 is stopped and heat absorption in the heat absorption section 20 is stopped, the amount of heat supplied from the heat absorption section 20 to the refrigerant on the low-pressure side will be immediately gone, 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 section 20 is continued from the heat pump heating mode. However, the switching control when switching operating modes is performed within a range that can maintain the amount of heat absorbed in the heat absorption section 20, thereby suppressing a decrease in the low-pressure pressure of the heat pump cycle 10. Hereinafter, the operation to maintain as much of the amount of heat absorbed on the low-pressure side of the heat pump cycle 10 as possible during the switching control of operating modes will be referred to as the heat absorption amount securing operation.

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

[0141] In the example shown in Figure 6, the vehicle air conditioning system 1 is operating in heat pump heating mode from time ta. As described above, in the vehicle air conditioning system 1 operating in heat pump heating mode, 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.

[0142] As described above, in heat pump heating mode, the throttle opening of the bypass-side expansion valve 14 is controlled to be fully closed. In addition, the rotational speed of the compressor 11, the throttle opening of the low-temperature-side expansion valve 19, the pumping 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 to meet the conditions specified for the heat pump heating mode described above.

[0143] At time tb, the decision is made to switch the operating mode from heat pump heating mode to hot gas heating mode, and the switching control in the vehicle air conditioning system 1 is initiated. The conditions for initiating the switching control include, for example, when the amount of heat absorbed from the heat absorption unit 20 is insufficient to meet 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 absorbed is determined based on the relationship between the target outlet temperature of the conditioned air and the temperature of the heat absorbed object (air) in the heat absorption unit 20.

[0144] Furthermore, the conditions for initiating the switching control are not limited to the examples described above. For example, the decision to switch from the heat pump heating mode to the hot gas heating mode may be made based on the operation of the occupant via the control panel 71.

[0145] When the control to switch from heat pump heating mode to hot gas heating mode is initiated at time tb, the operation modes of the rotation speed of the compressor 11, the throttle opening of the low-temperature side expansion valve 19, the pumping capacity of the low-temperature side pump 32, the blowing capacity of the indoor blower 62, and the opening degree of the air mix door 64 are controlled.

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

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

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

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

[0150] The pumping rate of the low-temperature pump 32 (i.e., the discharge rate of the heat transfer medium) is controlled during switching control to maintain the pumping rate of the heat pump heating mode. This ensures that during switching control, the amount of heat absorbed by the low-pressure refrigerant in the heat pump cycle 10 is maintained to be approximately the same as that of the heat pump heating mode. Maintaining the pumping rate of the low-temperature pump 32 during switching control is an example of heat absorption maintenance operation during switching control.

[0151] Furthermore, the airflow rate of the indoor fan 62 is controlled to a predetermined amount for the switching control, and operates to maintain the airflow rate at a predetermined value during the switching control. Since 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 time tb has elapsed, the airflow rate of the indoor fan 62 is controlled to gradually decrease toward the predetermined value at the time of the switching control.

[0152] In other words, in switching control, the amount of heat-to-be-heated material (blown air) supplied to the indoor condenser 16 that constitutes the heating unit 15 is limited by the operation control of the indoor blower 62. Therefore, in switching control, limiting the blowing capacity of the indoor blower 62 to a lower level than in the heat pump heating mode is an example of a limiting operation in switching control.

[0153] Furthermore, the opening of the air mix door 64 is controlled to a predetermined value such that the opening of the cold air bypass passage 65 is greater than in the heat pump heating mode. In other words, during the switching operation, the air mix door 64 is controlled so that most of the air that has passed through the cooler core 33a flows around the indoor condenser 16.

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

[0155] Thus, once time tb has elapsed and the operation control of each component related to the switching control has been performed, the high-pressure refrigerant pressure in the heat pump cycle 10 decreases. In Figure 6, the completion time of the various operations in the switching control is shown as time tc.

[0156] After time tc, while the switching control continues, the aforementioned limiting operation and heat absorption amount securing operation also continue. In switching control, the state in which the limiting operation and heat absorption amount securing operation are performed in parallel is called the first state of switching control.

[0157] Furthermore, because the limiting operation restricts 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 increases over time from the start of the limiting operation. In other words, the limiting operation in the switching control can improve the heating capacity of the heat pump cycle 10.

[0158] Furthermore, the heat absorption amount securing operation ensures that the amount of heat absorbed in the heat absorption section 20 on the low-pressure side of the heat pump cycle 10 is equivalent to that of the heat pump heating operation. As a result, the low-pressure pressure of the refrigerant gradually increases with the passage of time from the start of the heat absorption amount securing operation. Similarly, the temperature of the low-pressure refrigerant flowing through the heat absorption section 20 (i.e., the temperature of the low-pressure refrigerant flowing out from the refrigerant passage 21a of the chiller 21) also increases with the passage of time from time tc. In other words, the heat absorption amount securing operation in the switching control gradually increases the suction refrigerant density of the compressor 11, thereby increasing the amount of work done by the compressor 11.

[0159] Furthermore, the rotational 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 to maintain predetermined values ​​specified for switching control.

[0160] As a switching control, if the limiting operation and heat absorption amount securing operation are continued from time tc, the refrigerant temperature in the refrigerant passage 21a of the chiller 21 will reach a predetermined reference chiller side temperature KTc. The reference chiller side temperature KTc is determined based on the temperature of the heat transfer medium flowing through the heat transfer medium passage 21b of the chiller 21, and indicates that the amount of heat absorbed 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 above the predetermined reference chiller side temperature KTc is one example of a heat absorption stop condition.

[0161] Time td is defined as the point in 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, satisfying the heat absorption stop condition. Since time td is the point in time when the amount of heat absorbed in the heat absorption section 20 can no longer be sufficiently secured, even if the heat absorption securing operation is performed, it is difficult to raise the low-pressure refrigerant using the absorbed heat.

[0162] Therefore, after time td has elapsed, the operation of the low-temperature pump 32 is stopped, and the amount of heat transfer medium pumped by the low-temperature pump 32 is set to 0. As a result, the amount of heat absorbed by the chiller 21 that constitutes the heat absorption section 20 becomes sufficiently small, and the heat absorption amount securing operation in the switching control is terminated.

[0163] In the example shown in Figure 6, the operation to ensure heat absorption was terminated by stopping the operation of the low-temperature pump 32, but the system is not limited to this configuration. For example, as an example of an operation to reduce the amount of heat transfer medium supplied to the chiller 21 in order to terminate the operation to ensure heat absorption, the circulation path of the heat transfer medium in the low-temperature circuit 31 may be switched to a path that does not pass through the heat transfer medium passage 21b of the chiller 21. By switching the circulation path of the heat transfer medium as described above by controlling the operation of the three-way valve 34 of the heat transfer medium, the same effect as stopping the operation of the low-temperature pump 32 can be achieved.

[0164] By stopping the heat absorption operation as soon as the heat absorption stop conditions are met, the waste of energy required for the heat absorption operation can be suppressed, resulting in energy-efficient switching control.

[0165] Even after the heat absorption amount securing operation is completed, the circulation and limiting of the refrigerant in the heat pump cycle 10 under switching control continues. This state is called the second state of switching control. In the second state of switching control, because the limiting operation continues to be performed, the high-pressure pressure, low-pressure pressure, and low-pressure side refrigerant temperature of the refrigerant in the heat pump cycle 10 continue to rise with the passage of time, even after time td and the completion of the heat absorption amount securing operation.

[0166] As described above, the switching control is performed to suppress fluctuations in heating capacity when switching from heat pump heating mode to hot gas heating mode. As one way to suppress fluctuations in heating capacity, in the second state of the switching control, it is determined whether the high pressure of the refrigerant in the heat pump cycle 10 has risen to a state in which the heating capacity in hot gas heating mode is equivalent to that of heat pump heating mode.

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

[0168] Another method to suppress fluctuations in heating capacity when switching to hot gas heating mode is to increase the workload of the compressor 11 to a state equivalent to the heating capacity in hot gas heating mode during the second state of switching control. That is, during the second state of switching control, it is determined whether or not the low pressure of the refrigerant in the heat pump cycle 10 has become higher than the reference low 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 work done by the compressor 11 in the hot gas heating mode is equivalent to the heating capacity of the heat pump heating mode. If the low pressure in the heat pump cycle 10 under switching control is higher than the reference low pressure KPs, the hot gas heating mode can achieve a heating capacity equivalent to that of the heat pump heating, thereby suppressing fluctuations in heating capacity.

[0170] As shown in Figure 6, after time td has elapsed and the system transitions to the second state of switching control, the high-pressure and low-pressure in the heat pump cycle 10 gradually increase. Time te is defined as the point at which either the high-pressure in the heat pump cycle 10 becomes equal to or greater than the reference high-pressure KPd, or the low-pressure in the heat pump cycle 10 becomes equal to or greater than the reference low-pressure KPs.

[0171] In the example shown in Figure 6, the points at which the high pressure of the heat pump cycle 10 becomes equal to or greater than the reference high pressure KPd and the low pressure of the heat pump cycle 10 becomes equal to or greater than the reference low pressure KPs are met simultaneously. The example in Figure 6 is merely one example, and time te may be defined as the point at which either of the two conditions described above is met first. Furthermore, in consideration of reliably suppressing fluctuations in heating capacity, time te may be defined as the point at which both the high pressure condition and the low pressure condition are met.

[0172] When the conditions for the high-pressure or low-pressure side of the refrigerant in the heat pump cycle 10 are met and time te has elapsed, the switching control ends and the system switches to hot gas heating mode. By ending the limiting operation and switching to hot gas heating mode, provided that the conditions for the high-pressure side of the refrigerant are met, the heating capacity of the heat pump cycle 10 reaches a predetermined level (i.e., the level before the switching control), and the hot gas heating mode is started. This allows the hot gas heating mode to be started while suppressing fluctuations in the heating capacity of the blown air, which is the object to be heated.

[0173] Furthermore, provided that the conditions for the low-pressure side of the refrigerant are met, the limiting operation ends and the system switches to hot gas heating mode. This starts the hot gas heating mode when the workload of the compressor 11 reaches a predetermined level (i.e., the level before switching control). In this case as well, 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 hot gas heating mode, as described above, the control device 70 controls the operation of the compressor 11, bypass expansion valve 14, low-temperature expansion valve 19, low-temperature pump 32, indoor blower 62, air mix door 64, etc.

[0175] Specifically, in 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 specified for the hot gas heating mode. In addition, the rotational speed of the compressor 11, the airflow capacity of the indoor blower 62, and the opening of the air mix door 64 are controlled to meet the conditions specified for the hot gas heating mode as described above. When transitioning to hot gas heating mode following the switching control, the pumping volume of the low-temperature-side pump 32 remains at 0 to maintain the stopped state it was in when transitioning from the second state of the 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, switching control is performed to execute a limiting operation, allowing the hot gas heating mode to be started with a sufficiently high heating capacity of the heat pump cycle 10. This makes it possible to switch operating modes while suppressing the difference in heating capacity caused by the configuration of the refrigerant circuits in the heat pump heating mode and the hot gas heating mode.

[0177] As shown in Figure 6, as a limiting operation of the switching control, the operation of the indoor blower 62 is controlled to limit the amount of blown air supplied to the indoor condenser 16 that constitutes the heating unit 15. By limiting the amount of blown air supplied by the indoor blower 62, the amount of heat dissipated on the high-pressure side of the heat pump cycle 10 can be limited, thereby improving the heating capacity on the high-pressure side of the heat pump cycle 10.

[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. The operation of the air mix door 64 allows for limiting the amount of blown air supplied to the indoor condenser 16 in terms of the airflow path of the object to be heated. Therefore, the limiting operation related to the operation control of the air mix door 64 ensures that the heating capacity of the heat pump cycle 10 is sufficiently secured before switching to the hot gas heating mode.

[0179] As shown in Figure 6, in switching control, the limiting operation and the heat absorption amount securing operation are performed in parallel. In other words, by performing the limiting operation and the heat absorption amount securing operation in parallel, it is possible to utilize both the perspective of heating capacity on the high-pressure side of the heat pump cycle 10 and the perspective of the amount of work of the compressor 11 due to the low-pressure side of the heat pump cycle 10. As a result, when switching from heat pump heating mode to hot gas heating mode, the period during which the heating capacity of the object to be heated fluctuates can be shortened and the fluctuation can be kept to a minimum.

[0180] In the switching control of the first embodiment, the heat absorption amount securing operation is performed in parallel with the operation of the chiller 21 absorbing heat from the heat transfer medium for the low-pressure refrigerant, similar to heat pump heating, by circulating a portion of the refrigerant discharged from the compressor 11 through the bypass passage 13. This increases the low-pressure of the heat pump cycle 10, improves the workload of the compressor 11, and realizes a circuit configuration that facilitates transitioning to the hot gas heating mode.

[0181] As shown in Figure 6 at time td, the heat absorption maintenance operation in switching control is terminated when the heat absorption stop condition is met and the heat absorption amount falls below a predetermined standard. In other words, the heat absorption maintenance operation can be efficiently executed in switching control, thereby suppressing fluctuations in heating capacity.

[0182] Furthermore, as shown in Figure 6, when the heat absorption amount securing 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 transfer medium supplied from the heat absorption section 20 to the chiller 21 is reduced to zero. With simple operation control, a reduction in the amount of heat absorbed via the heat transfer medium can be achieved in the heat absorption section 20.

[0183] As described above, according to the vehicle air conditioning system 1 of the first embodiment, in the switching control when switching from the heat pump heating mode to the hot gas heating mode, a limiting operation is performed to limit the amount of heat emitted from the indoor condenser 16 that constitutes the heating unit 15. By performing a limiting operation in the switching control, the heating capacity on 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 suppressed to a small extent.

[0184] As shown in Figure 6, as a limiting operation of the switching control, the operation of the indoor blower 62 is controlled to limit the amount of blown air supplied to the indoor condenser 16 that constitutes the heating unit 15. By limiting the amount of blown air supplied by the indoor blower 62, the amount of heat dissipated on the high-pressure side of the heat pump cycle 10 can be limited, thereby improving the heating capacity on the high-pressure side of the heat pump cycle 10.

[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. The operation of the air mix door 64 limits the amount of blown air supplied to the indoor condenser 16 in terms of the airflow path of the object to be heated. Therefore, the limiting operation related to the operation control of the air mix door 64 ensures that the heating capacity of the heat pump cycle 10 is sufficiently secured before switching to the hot gas heating mode.

[0186] As shown in Figure 6 from time tc to time te, the limiting operation in the switching control releases the heat dissipation limit when the high pressure of the heat pump cycle 10 becomes equal to or greater than the reference high pressure KPd. The state in which the high pressure becomes equal to or greater than the reference high 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 heating capacity can be suppressed, and the system can transition to the hot gas heating mode.

[0187] Furthermore, the limiting operation in the switching control releases the heat dissipation limit when the low pressure of the heat pump cycle 10 becomes equal to or greater than the reference low pressure KPs. The state in which the low pressure becomes equal to or greater than the reference low pressure 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 switch to hot gas heating mode when fluctuations in 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 securing operation are performed in parallel before transitioning to hot gas heating mode. The limiting operation improves the heating capacity of the heat pump cycle 10, while the heat absorption amount securing operation increases the workload of the compressor 11. Therefore, by performing the limiting operation and the heat absorption amount securing operation in parallel, the required period for switching control can be shortened, and fluctuations in heating capacity can be suppressed in a short period of time.

[0189] Furthermore, in the switching control when switching from the heat pump heating mode to the hot gas heating mode, an operation is performed to ensure that the amount of heat absorbed in the heat absorption section 20 is approximately the same as before the switch. By performing the heat absorption amount ensuring operation in the switching control, the density of the refrigerant drawn into the compressor 11 is increased, which significantly increases the amount of work done by the compressor 11, and thus minimizes fluctuations in heating capacity between the heat pump heating mode and the hot gas heating mode.

[0190] As described above, in the heat pump cycle 10 when the heat absorption amount securing operation is 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. In the heat absorption amount securing operation in switching control, the same two refrigerant circulation paths as in the hot gas heating mode are maintained concurrently, so the transition from switching control to the hot gas heating mode can be performed quickly and with simple operation.

[0191] As shown at time td in Figure 6, the heat absorption amount securing operation in the switching control terminates 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 where the amount of heat absorbed in the heat absorption unit 20 becomes small, and there is little need to continue the heat absorption amount securing operation. In other words, by terminating the heat absorption amount securing operation when the heat absorption stop condition is met, the vehicle air conditioning system 1 can efficiently execute the switching control and transition to the hot gas heating mode in a manner that suppresses fluctuations in heating capacity.

[0192] Then, when the heat absorption amount securing operation is terminated and heat absorption in the heat absorption section 20 is suppressed, the pumping rate of the low-temperature side pump 32 is reduced to zero. In other words, heat absorption is suppressed by reducing the amount of heat transfer medium constituting the object to be absorbed supplied to the chiller 21 that constitutes the heat absorption section 20. By adopting this configuration, heat absorption in the heat absorption section 20 can be suppressed by simple control.

[0193] (Second Embodiment) Next, a second embodiment, which differs from the embodiment described above, will be described with reference to Figures 7 to 9. The heat pump cycle device according to the second embodiment is applied to a vehicle air conditioning system 1 mounted on an electric vehicle, similar to the first embodiment. However, in the vehicle air conditioning system 1 according to the second embodiment, the configuration of the heat absorption section 20 has been changed from that of the first embodiment described above, and it is configured as a heating system for a vehicle.

[0194] Other components of the vehicle air conditioning system 1 according to the second embodiment (heat pump cycle 10, indoor air conditioning unit 60, etc.) are the same as those in the embodiment described above, so a further explanation will be omitted.

[0195] As shown in Figure 7, the heat absorption section 20 of the vehicle air conditioning system 1 according to the second embodiment is composed of an outside air heat absorber 22, unlike in the first embodiment. Also, in the second embodiment, unlike in the first embodiment, the heat transfer medium circuit 30 and the components associated with the heat transfer medium circuit 30 have been eliminated. Specifically, the low-temperature side pump 32, outside air heat exchanger 33, heat transfer medium three-way valve 34, etc., which were located in the low-temperature side circuit 31 of the heat transfer medium circuit 30, are located in the second embodiment.

[0196] The heat pump cycle 10 according to the second embodiment has the same configuration as the first embodiment described above, except that the configuration of the heat absorption section 20 is different. The outside air heat absorber 22 is located between the outlet side of the low-temperature side expansion valve 19 and the confluence section 12b, similar to the chiller 21 in the first embodiment. 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 the outside air present outside the passenger compartment of the electric vehicle, thereby absorbing the heat contained in the outside air into the low-pressure refrigerant. In other words, the object of heat absorption in the heat absorption section 20 of the second embodiment is the outside air.

[0197] Furthermore, the method of supplying outside air to the outside air heat absorber 22 is not particularly limited; for example, it may be supplied by the operation of an outside air fan (not shown), or a configuration utilizing the airflow from an electric vehicle may be adopted.

[0198] Furthermore, a shutter device 23 is positioned upstream of the outside air flow to the outside air heat absorber 22. The shutter device 23 is constructed by rotatably arranging multiple blades in an opening in a frame-shaped structure. The multiple blades rotate in conjunction with the operation of an electric actuator (not shown), adjusting the opening area in 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 absorber 22, and thus adjust the amount of heat absorbed by the outside air heat absorber 22. Therefore, the shutter device 23 is an example of a heat absorption adjustment unit.

[0200] In the vehicle air conditioning system 1 configured in this manner according to the second embodiment, a heat pump heating mode and a hot gas heating mode can also be realized. In the heat pump heating mode according to the second embodiment, the bypass-side expansion valve 14 is set to a fully closed state, and the low-temperature-side expansion valve 19 is adjusted to a throttled state. At this time, the shutter device 23 is set to ensure an opening area so that outside air is supplied to the outside air heat absorber 22.

[0201] By controlling the operation in this manner, the heat pump cycle 10 absorbs heat from the outside air in the outside air absorber 22 that constitutes the heat absorption section 20, and also pumps up the absorbed heat and releases it into the blown air in the indoor condenser 16 that constitutes the heating section 15. The heat pump heating mode according to the second embodiment is also an example of the first heating mode, similar to the first embodiment.

[0202] In the hot gas heating mode according to the second embodiment, the bypass-side expansion valve 14 and the low-temperature-side expansion valve 19 are set to predetermined throttling states, and the refrigerant is circulated in the heat pump cycle 10. At this time, the shutter device 23 is controlled to minimize its opening area, thereby achieving a state in which the amount of outside air supplied to the outside air heat absorber 22 is minimized.

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

[0204] As described above, in the hot gas heating mode, refrigerants with different enthalpy properties, such as the low-enthalpy refrigerant flowing out from the outside air heat absorber 22 and the high-enthalpy refrigerant flowing out from the bypass passage 13, are mixed and drawn into the compressor 11. Therefore, similar to 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 achieving heating inside the vehicle. In other words, the hot gas heating mode according to the second embodiment is also an example of the second heating mode.

[0205] In the vehicle air conditioning system 1 according to the second embodiment, it is conceivable that the heating capacity may be insufficient while the heat pump heating mode is in operation. For example, if the outside temperature is too low compared to the required heating capacity, the heat pump heating mode may not be sufficient, and it may be desirable to switch to the hot gas heating mode.

[0206] Therefore, in the second embodiment as well, 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] In the vehicle air conditioning system 1 according to the second embodiment, when switching control is started, the rotational speed of the compressor 11 is controlled to a predetermined rotational speed, and the throttle openings of the bypass-side expansion valve 14 and the low-temperature-side expansion valve 19 are controlled to a predetermined value, similar to the first embodiment.

[0208] Then, upon commencement 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 performed. In the switching control of the second embodiment, as an operation to ensure the amount of heat absorbed, the shutter device 23 is operated so as to maximize the opening area in order to ensure the amount of outside air supplied to the outside air heat absorber 22.

[0209] As a result, the vehicle air conditioning system 1 of the second embodiment achieves refrigerant circulation in the heat pump cycle 10 in the manner shown in Figure 8. In this first state, the amount of heat dissipated in the heating unit 15 is limited by the limiting operation, and the amount of heat absorbed in the outside air heat absorber 22 is secured by the heat absorption securing operation. As a result, the heating capacity after the switchover is completed can be increased to be equivalent to that before the switchover, from the perspective of the high-pressure and low-pressure sides of the heat pump cycle 10, and fluctuations in heating capacity can be suppressed.

[0210] Then, when transitioning to the second state in the switching control of the second embodiment, the heat absorption amount securing operation that was performed in the first state is stopped, and only the limiting operation is performed. The transition from the first state to the second state in the switching control occurs when the amount of heat absorbed in the heat absorption section 20 becomes low, similar to the first embodiment described above. Therefore, the timing of the transition is determined by the relationship between the temperature of the low-pressure refrigerant in the outside air heat absorber 22 and the outside temperature.

[0211] From the first state of the switching control according to the second embodiment, the operation control of the shutter device 23 minimizes the amount of outside air supplied to the outside air heat absorber 22, thereby ending the heat absorption amount securing operation. As a result, as shown in Figure 9, the second state of the switching control according to the second embodiment is realized. Note that even in the second state of the switching control, the refrigerant circulation and limiting operation continues to be performed.

[0212] This allows for increased heating capacity to the same level as before the switchover, by limiting heat dissipation while suppressing energy consumption associated with heat absorption maintenance when heat absorption is reduced.

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

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

[0215] (Third embodiment) Next, a third embodiment, which differs from the embodiments described above, will be described with reference to Figures 10 to 12. In the vehicle air conditioning system 1 according to the third embodiment, the configuration of the heat pump cycle 10 has been changed from the heat pump cycle 10 in the embodiments described above. The other components of the vehicle air conditioning system 1 according to the third embodiment (heat transfer medium circuit 30, indoor air conditioning unit 60, etc.) are the same as in the embodiments described above, so a further explanation will be omitted.

[0216] As shown in Figure 10, the vehicle air conditioning system 1 according to the third embodiment comprises a heat pump cycle 10, a heat transfer medium circuit 30, an indoor air conditioning unit 60, and a control device 70. The configuration of the heat transfer medium circuit 30, the indoor air conditioning unit 60, the control device 70, etc., is the same as that of the first embodiment described above, so a further explanation will be omitted.

[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 outside air absorber 22, a first expansion valve 26, a second expansion valve 27, and an accumulator 28. That is, unlike the embodiments described above, the heat pump cycle 10 according to the third embodiment is configured as a parallel circuit in which the chiller 21 and the outside air 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 branching section 12a is connected to the discharge port of the compressor 11. The configuration of the compressor 11 and the branching section 12a is the same as in the first embodiment, so a further explanation is omitted.

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

[0220] A three-way joint-shaped first connection section 24 is located on the outlet side of the indoor condenser 16. The first connection section 24 has one inlet and two outlets. One of the outlets of the first connection section 24 is connected to the first expansion valve 26 and the refrigerant passage 21a of the chiller 21. The other outlet of the first connection section 24 is connected to the second expansion valve 27 and the outside air heat absorber 22.

[0221] Here, the first expansion valve 26 and the second expansion valve 27 are electrically operated expansion valves configured in the same manner as the low-temperature side expansion valve 19 described above. Therefore, the first expansion valve 26 and the second expansion valve 27 have valve bodies and electric actuators, and their operation is controlled by control pulses 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] A chiller 21, which constitutes the heat absorption section 20, is connected to the outlet side of the first expansion valve 26. Similar to the first embodiment, the chiller 21 has a refrigerant passage 21a and a heat transfer medium passage 21b, and exchanges heat between the refrigerant flowing through the refrigerant passage 21a and the heat transfer medium flowing through the heat transfer medium passage 21b. A four-way joint-shaped second connection part 25 is connected to the outlet side of the refrigerant passage 21a of the chiller 21.

[0223] Furthermore, the heat transfer medium flowing through the heat transfer medium passage 21b is the same as the heat transfer medium circulating in the low-temperature side circuit 31 as in the first embodiment. The low-temperature side circuit 31 has a low-temperature side pump 32, an outside air heat exchanger 33, a heat transfer 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 a chiller 21 as the heat absorption section 20, the heat contained in the outdoor air as a heat absorption source can be absorbed by the low-pressure refrigerant via the heat transfer medium of the low-temperature side circuit 31.

[0225] An outside air absorber 22, which constitutes the heat absorption section 20, is connected to the outlet side of the second expansion valve 27. Similar to the second embodiment, the outside air absorber 22 exchanges heat between the heat transfer medium flowing through the outside air absorber 22 and the outside air outside the vehicle compartment. A four-way joint-shaped second connection section 25 is connected to the outlet side of the outside air absorber 22.

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

[0227] The second connection section 25 is formed in a four-way joint shape and has three inlets and one outlet. One of the inlets in the second connection section 25 is connected to the other end of the bypass passage 13 and the bypass-side expansion valve 14. The other inlet in the second connection section 25 is connected to the outlet side of the refrigerant passage 21a of the chiller 21. Another inlet in the second connection section 25 is connected to the outlet side of the outside air absorber 22.

[0228] Furthermore, the outlet side of the second connection section 25 is connected to the inlet side of the accumulator 28. In other words, the second connection section 25 constitutes a merging section 12b that merges the refrigerant flow via the bypass passage 13, the refrigerant flow via the chiller 21, and the refrigerant flow via the outside air heat absorber 22, and leads them to the accumulator 28.

[0229] The outlet side of the second connection section 25, which constitutes the confluence section 12b, is connected to the inlet side of the accumulator 28. The accumulator 28 is a low-pressure gas-liquid separator that separates the gas-liquid phase of the low-pressure refrigerant flowing out from the second connection section 25 and stores the separated liquid-phase refrigerant as excess refrigerant in the cycle. The inlet side of the compressor 11 is connected to the gas-phase refrigerant outlet of the accumulator 28.

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

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

[0232] As a result, in the heat pump cycle 10 of the heat pump heating mode according to the third embodiment, the refrigerant circulates in the following order: compressor 11, branch 12a, indoor condenser 16, first connection 24, second expansion valve 27, outside air heat absorber 22, second connection 25, and accumulator 28.

[0233] In other words, in the heat pump heating mode according to the third embodiment, a refrigerant circuit is configured in which the outside air absorber 22 is used as an absorber and the indoor condenser 16 is used as a radiator, and heating operation is realized in which the outside air is used as a heat source 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] Furthermore, as another example of the heat pump heating mode according to the third embodiment, a configuration can also be adopted in which the bypass-side expansion valve 14 and the second expansion valve 27 are fully closed, and the first expansion valve 26 is set to a predetermined throttling state. In this case, the heat transfer medium circuit 30 is controlled to circulate via the chiller 21 and the outside air heat exchanger 33. With this configuration, a heat pump heating mode using outside air as a heat source can be realized.

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

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

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

[0238] In other words, in the hot gas heating mode according to the third embodiment, refrigerants with different enthalpy properties, 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 confluence section 12b. By mixing refrigerants with different enthalpy properties 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 conditioning system 1 according to the third embodiment, it is conceivable that the heating capacity may be insufficient while the heat pump heating mode is in operation. For example, if the outside temperature is too low compared to the required heating capacity, the heat pump heating mode may not be sufficient, and it may be desirable to switch to the hot gas heating mode.

[0240] Therefore, in the third embodiment as well, 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 conditioning system 1 according to the third embodiment, when switching control is started from the heat pump heating mode, the rotation speed of the compressor 11 is controlled to a predetermined rotation speed, similar to the first embodiment. At this time, the throttle openings of the bypass-side expansion valve 14, the first expansion valve 26, and the second expansion valve 27 are controlled to predetermined values. In addition, in the heat transfer medium circuit 30, the circulation of the heat transfer medium via the chiller 21 is stopped by stopping the operation of the low-temperature side pump 32.

[0242] Then, upon commencement of the switching control, the operation of the indoor fan 62 and the air mix door 64 is controlled, and the same limiting operation as in the embodiment described above is performed. In the switching control of the third embodiment, as an operation to ensure the amount of heat absorbed, heat is absorbed from the outside air by the outside air heat absorber 22.

[0243] Furthermore, if the shutter device 23 is positioned relative to the outside air heat absorber 22, the shutter device 23 will operate in a manner that maximizes the opening area in order to ensure a sufficient supply of outside air to the outside air heat absorber 22, similar to the second embodiment.

[0244] As a result, the vehicle air conditioning system 1 of the third embodiment achieves refrigerant circulation in the heat pump cycle 10 in the manner shown in Figure 11. In this first state, the amount of heat dissipated in the heating unit 15 is limited by the limiting operation, and the amount of heat absorbed in the outside air heat absorber 22 is secured by the heat absorption securing operation. As a result, the heating capacity after the switchover is made equivalent to that before the switchover, from the perspective of the high-pressure and low-pressure sides of the heat pump cycle 10, and fluctuations in heating capacity before and after the switchover can be suppressed.

[0245] Then, when transitioning to the second state in the switching control of the third embodiment, the heat absorption amount securing operation that was performed in the first state is stopped, and only the limiting operation is performed. The transition from the first state to the second state in the switching control occurs when the amount of heat absorbed in the heat absorption section 20 becomes low, similar to the embodiments described above. Therefore, the timing of the transition is determined by the relationship between the temperature of the low-pressure refrigerant in the outside air heat absorber 22 and the outside temperature.

[0246] The transition from the first state to the second state of the switching control according to the third embodiment (i.e., the termination of the heat absorption amount securing operation) is achieved by changing the refrigerant flow path in the heat pump cycle 10. As shown in Figure 11, when the heat absorption amount securing operation is being performed, a portion of the refrigerant that has passed through the first connection part 24 flows through the second expansion valve 27 and the outside air heat absorber 22, thereby absorbing heat from the outside air. When the heat absorption amount securing operation is terminated, 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 throttled state in the first state to the fully closed state. As a result, the supply of low-pressure refrigerant to the outside air heat absorber 22 is stopped, and the heat absorption amount securing operation is terminated. Note that even in the second state of the switching control, the circulation and limiting of refrigerant continues to be performed.

[0248] As a result, as shown in Figure 12, the second state of the switching control related to the third implementation mode is realized. Then, by limiting the amount of heat dissipation while suppressing energy consumption for heat absorption maintenance when the amount of heat absorbed has decreased, the heating capacity can be increased to a state in which the same level of heating capacity as before the switching can be achieved.

[0249] In other words, in the vehicle air conditioning system 1 according to the third embodiment, by performing switching control when switching from the heat pump heating mode to the hot gas heating mode, fluctuations in heating capacity associated with the 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 is adopted in which a plurality of heat absorbers constituting the heat absorption section 20 are arranged in parallel, the effects and advantages obtained from the configuration and operation common to the above-described embodiment can be obtained.

[0251] Furthermore, as shown in Figures 11 and 12, in the vehicle air conditioning system 1 according to the third embodiment, the heat absorption amount securing operation is terminated by switching the flow of refrigerant through the outside air heat absorber 22, which was used in the heat absorption amount securing operation. With the termination of the heat absorption amount securing operation, the flow of refrigerant through the outside air heat absorber 22, which was absorbing heat in the heat absorption amount securing operation, is switched to the flow of refrigerant through the chiller 21, which is 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 conditioning system 1 according to the third embodiment, a plurality of heat absorbers (chiller 21, outside air heat absorber 22) constituting the heat absorption section 20 are arranged in parallel, and a heat absorption amount securing operation is performed using one of the heat absorbers. When the heat absorption amount securing operation is terminated, the refrigerant flow path on the low-pressure side is switched from a configuration that passes through one of the heat absorbers (outside air heat absorber 22) to a configuration that passes through the other heat absorber (chiller 21). As a result, the heat absorption amount securing operation can be terminated by switching the refrigerant flow path, and the heat absorption related to the heat absorption amount securing operation can be suppressed by simple control.

[0253] (Fourth Embodiment) Next, a fourth embodiment, which differs from the embodiments described above, will be described with reference to Figures 13 to 16. The fourth embodiment is an embodiment in which the heat pump cycle device according to the present disclosure is applied to an air conditioning system 1 for an electric vehicle, similar to the embodiments described above. The fourth embodiment is characterized in that, similar to the embodiments described above, it suppresses fluctuations in heating capacity when switching between multiple operating modes for heating the object to be heated.

[0254] In the fourth embodiment, the operating mode is also performed in which the heat absorbed on the low-pressure side of the heat pump cycle 10 is pumped up and used to heat the object to be heated, and 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, although the details of the operating modes in the fourth embodiment differ, they are based on the same concept as the embodiments described above in the respects described above.

[0255] The vehicle air conditioning system 1 according to the fourth embodiment consists of a heat pump cycle 10, a heat transfer medium circuit 30, an interior air conditioning unit 60, and a control device 70. In the fourth embodiment, the configuration of the heat pump cycle 10 and the heat transfer medium circuit 30 differs from that of the embodiments described above. In other words, the other components of the vehicle air conditioning system 1 according to the fourth embodiment (interior air conditioning unit 60, control device 70, etc.) are basically the same as those of the embodiments described above, so a further explanation is omitted.

[0256] As shown in Figure 13, the heat pump cycle 10 of the vehicle air conditioning system 1 according to the fourth embodiment includes a compressor 11, a 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 embodiments described above. Therefore, a detailed explanation of the compressor 11 is omitted.

[0257] The refrigerant inlet side of the heat transfer medium refrigerant heat exchanger 17 is connected to the discharge side of the compressor 11. The heat transfer 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 transfer medium passage 17b through which the heat transfer medium that circulates in the high-temperature side circuit 41 that constitutes the heat transfer medium circuit 30 flows.

[0258] The heat transfer medium refrigerant heat exchanger 17 is a condenser that condenses the high-pressure refrigerant flowing through the refrigerant passage 17a and the heat transfer medium flowing through the heat transfer medium passage 17b by exchanging heat. In other words, the heat transfer medium refrigerant heat exchanger 17 heats the heat transfer medium by releasing the heat contained in the high-pressure refrigerant discharged from the compressor 11 to the heat transfer medium circulating in the heat transfer medium circuit 30. For this reason, the heat transfer medium refrigerant heat exchanger 17 constitutes a part of the heating section 15.

[0259] A low-temperature side expansion valve 19 is connected to the outlet side of the refrigerant passage 17a of the heat transfer medium refrigerant heat exchanger 17. The configuration of the low-temperature side expansion valve 19 is the same as in the embodiment described above, and it has a valve body and an electric actuator. The operation of the low-temperature side expansion valve 19 is controlled by control pulses 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 expansion valve 19 is connected to the inlet side of the refrigerant passage 21a of the chiller 21. The chiller 21, as in the embodiment described above, has a refrigerant passage 21a and a heat transfer medium passage 21b, and exchanges heat between the refrigerant flowing through the refrigerant passage 21a and the heat transfer medium flowing through the heat transfer medium passage 21b. Therefore, the chiller 21 constitutes part of the heat absorption section 20, which absorbs the heat contained in the heat transfer medium flowing through the heat transfer 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 port side of the compressor 11.

[0261] The heat pump cycle 10 according to this fourth embodiment, configured in this way, can pump up the heat absorbed in the low-pressure heat absorption section 20 and release it in the high-pressure heating section 15 to be used for heating the object to be heated.

[0262] Next, the heat transfer medium circuit 30 of the vehicle air conditioning system 1 according to the fourth embodiment will be described. As shown in Figure 13, the heat transfer medium circuit 30 according to the fourth embodiment is configured to include a low-temperature side circuit 31, a high-temperature side circuit 41, a heat transfer medium connection flow path 50, and a heat transfer medium flow rate adjustment unit 55.

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

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

[0265] Here, as shown in Figure 13, the low-temperature side circuit 31 according to the fourth embodiment includes, in addition to the chiller 21 and the low-temperature side pump 32 to the heat transfer medium bypass flow path 36 described above, 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 electrically operated three-way flow control valve having three inlets and outlets, and is configured to allow continuous adjustment of 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 located between the outlet side of the heat transfer medium passage 21b of the chiller 21 and the bypass connection unit 35. Specifically, one of the inlets and outlets of the low-temperature side flow rate adjustment unit 37 is connected to the outlet side of the heat transfer medium passage 21b of the chiller 21, and the other inlet and outlet of the low-temperature side flow rate adjustment unit 37 is connected to one of the inlets and outlets of the bypass connection unit 35. The other inlet and outlet of the low-temperature side flow rate adjustment unit 37 is connected to the second connecting passage 52. The second connecting passage 52 will be described later.

[0268] The low-temperature side connection section 38 is formed in the shape of a three-way joint having three inlet and outlet ports, and is positioned between the inlet side of the heat transfer medium passage 21b of the chiller 21 and the three-way heat transfer medium valve 34. Therefore, one inlet and outlet of the low-temperature side connection section 38 is connected to the inlet side of the heat transfer medium passage 21b of the chiller 21, and one of the outlets of the three-way heat transfer medium valve 34 is connected to the other inlet and outlet of the low-temperature side connection section 38. The first connecting passage 51 is connected to the other inlet and outlet of the low-temperature side connection section 38. The first connecting passage 51 will be described later.

[0269] According to the low-temperature side circuit 31 configured in this way according to the fourth embodiment, multiple circulation modes of the heat transfer medium can be realized by controlling the operation of the heat transfer medium three-way valve 34 and the like. As one of the circulation modes of the heat transfer medium in the low-temperature side circuit 31, the heat transfer medium is circulated in the following order: low-temperature side pump 32, outside air heat exchanger 33, heat transfer medium three-way valve 34, low-temperature side connection part 38, chiller 21, low-temperature side flow rate adjustment part 37, bypass connection part 35, and low-temperature side pump 32.

[0270] Furthermore, as another circulation mode for the heat transfer medium in the low-temperature side circuit 31, it is possible to circulate the heat transfer medium in the following order: low-temperature side pump 32, outside air heat exchanger 33, heat transfer medium three-way valve 34, heat transfer medium bypass flow path 36, bypass connection part 35, and low-temperature side pump 32. Accordingly, the low-temperature side circuit 31 according to the fourth embodiment corresponds to an example of the second circuit, and the outside air heat exchanger 33 in the fourth embodiment corresponds to an example of a heat transfer medium absorber. The low-temperature side circuit 31, together with the chiller 21, constitutes the heat absorption section 20.

[0271] Next, the configuration of the high-temperature side circuit 41 of the heat transfer medium circuit 30 according to the fourth embodiment will be described with reference to Figure 13. The high-temperature side circuit 41 according to the fourth embodiment is a circuit in which the heat transfer medium circulates through the heat transfer medium refrigerant heat exchanger 17 that constitutes the heating section 15 of the heat transfer medium circuit 30. In addition to the heat transfer medium passage 17b of the heat transfer medium refrigerant heat exchanger 17, the high-temperature side circuit 41 according to the fourth embodiment is equipped with a high-temperature side pump 42, a heater core 43, a high-temperature side flow rate adjustment unit 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 transfer medium passage 17b of the heat transfer medium refrigerant heat exchanger 17. The high-temperature side pump 42 is a heat transfer medium pumping unit configured in the same way as the low-temperature side pump 32 described above. The pumping capacity of the high-temperature side pump 42 is controlled by a control voltage output from the control device 70.

[0273] Furthermore, a heater core 43 is connected to the inlet side of the heat transfer medium passage 17b of the heat transfer medium refrigerant heat exchanger 17. Similar to the indoor condenser 16 in the embodiment described above, it is located inside the air conditioning case 61 of the indoor air conditioning unit 60. The heater core 43 is an air heat exchange section that exchanges heat between the heat transfer medium that has flowed out of the heat transfer medium refrigerant heat exchanger 17 and the blown air that has passed through the cooler core 33a. In the heater core 43, the heat contained in the heat transfer medium that has flowed out of the heat transfer medium refrigerant heat exchanger 17 is released into the blown air, and the blown air is heated. Therefore, the heater core 43 corresponds to an example of a heat transfer medium radiator.

[0274] A high-temperature side flow rate adjustment unit 44 is connected to the heat transfer medium outlet side of the heater core 43. The high-temperature side flow rate adjustment unit 44, like the low-temperature side flow rate adjustment unit 37, is composed of an electric three-way flow control 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 outlets in the high-temperature side flow rate adjustment section 44 is connected to the outlet side of the heat transfer medium passage 17b of the heat transfer medium refrigerant heat exchanger 17, and the other outlet in the high-temperature side flow rate adjustment section 44 is connected to one of the outlets in the three-way joint-shaped high-temperature side connection section 45. The remaining outlet in the high-temperature side flow rate adjustment section 44 is connected to the first connection channel 51 which constitutes the heat transfer medium connection channel 50.

[0276] As shown in Figure 13, a three-way joint-type high-temperature side connection section 45 is connected to the suction port side of the high-temperature side pump 42. The configuration of the high-temperature side connection section 45 is the same as that of the branch section 12a and the low-temperature side connection section 38 described above. As described above, the suction port side of the high-temperature side pump 42 is connected to one of the inlet and outlet ports of the high-temperature side connection section 45, and the other inlet and outlet port of the high-temperature side connection section 45 is connected to the other side of the inlet and outlet port of the high-temperature side flow rate adjustment section 44. The second connection channel 52 is connected to the remaining inlet and outlet port of the high-temperature side connection section 45.

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

[0278] In other words, according to the high-temperature side circuit 41 of the fourth embodiment, the heat transfer medium heated by the heat of the high-pressure refrigerant in the heat transfer medium refrigerant heat exchanger 17 is flowed into the heater core 43, and the blown air can be heated by the heat of the heat transfer 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] Furthermore, the heat transfer medium circuit 30 according to the fourth embodiment has a heat transfer medium connection channel 50 that connects the high-temperature side circuit 41 and the low-temperature side circuit 31 so that the heat transfer medium can flow in and out. As shown in Figure 13, the heat transfer medium connection channel 50 is composed of a first connection channel 51 and a second connection channel 52.

[0280] As described above, the first connection flow path 51 connects one of the inlet / outlets of the high-temperature side flow rate adjustment section 44 disposed on the high-temperature side circuit 41 side and one of the inlet / outlets of the low-temperature side connection section 38 disposed on the low-temperature side circuit 31 side. Therefore, by controlling the operation of the high-temperature side flow rate adjustment section 44 to open the inlet / outlet on the high-temperature side flow rate adjustment section 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] Also, the second connection flow path 52 connects one of the inlet / outlets of the low-temperature side flow rate adjustment section 37 disposed on the low-temperature side circuit 31 side and one of the inlet / outlets of the high-temperature side connection section 45 disposed on the high-temperature side circuit 41 side. Therefore, by controlling the operation of the low-temperature side flow rate adjustment section 37 to open the inlet / outlet on the low-temperature side flow rate adjustment section 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] And since the low-temperature side flow rate adjustment section 37 and the high-temperature side flow rate adjustment section 44 are controlled when the heat medium flows in and out through the heat medium connection flow path 50, they correspond to an example of a flow rate adjustment section.

[0283] In the fourth embodiment, two types of heating modes are included as the operation modes of the vehicle air conditioner 1 that heats the blown air, which is the object to be heated. In the vehicle air conditioner 1 according to the fourth embodiment, heating inside the vehicle can be realized using the independent circulation heating mode and the circuit cooperation heating mode.

[0284] First, the independent circulation heating mode in 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 absorbed from the heat absorption source (the air inside the vehicle) is pumped up through the heat medium of the low-temperature side circuit 31, and heat is radiated to the blown air by the heater core 43 through the heat medium of the high-temperature side circuit 41, thereby heating the blown air. Therefore, the independent circulation heating mode according to the fourth embodiment can be said to be an aspect of the heat pump heating mode.

[0285] The control device 70 compresses and discharges the refrigerant using the compressor 11, and also throttles the low-temperature side expansion valve 19. Therefore, in the independent circulation heating mode heat pump cycle 10, the refrigerant is switched to a refrigerant circuit that circulates in the following order: compressor 11, heat transfer medium refrigerant heat exchanger 17, low-temperature side expansion valve 19, chiller 21, and compressor 11.

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

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

[0288] With respect to the low-temperature side circuit 31 of the heat transfer fluid circuit 30, the control device 70 determines the pumping capacity of the low-temperature side pump 32 and the ratio of the opening areas of the three outlets of the heat transfer fluid three-way valve 34 so as to ensure the amount of heat absorbed 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 completely close the inlet / outlet on the second connecting flow path 52 side, while simultaneously opening the inlet / outlet on the chiller 21 side and the bypass connection unit 35 side.

[0289] As a result, in the low-temperature side circuit 31 of the independent circulation heating mode, the heat transfer medium circulates in the following order: low-temperature side pump 32, outside air heat exchanger 33, heat transfer medium three-way valve 34, low-temperature side connection part 38, chiller 21, low-temperature side flow rate adjustment part 37, bypass connection part 35, and low-temperature side pump 32. In other words, in the low-temperature side circuit 31 of the independent circulation heating mode, there is no inflow or outflow of the heat transfer medium via the heat transfer medium connection flow path 50, and the heat transfer medium circulates independently within the low-temperature side circuit 31.

[0290] On the other hand, with respect to the high-temperature side circuit 41 of the heat transfer 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 discharge temperature. At this time, the control device 70 controls the operation of the high-temperature side flow rate adjustment unit 44 so as to completely close the inlet and outlet on the first connection flow path 51 side, while simultaneously connecting the inlet and outlet on the heat transfer medium refrigerant heat exchanger 17 side and the high-temperature side connection unit 45 side.

[0291] As a result, in the high-temperature side circuit 41 of the independent circulation heating mode, the heat transfer medium circulates in the following order: high-temperature side pump 42, heat transfer medium refrigerant heat exchanger 17, heater core 43, high-temperature side flow rate adjustment unit 44, high-temperature side connection unit 45, and high-temperature side pump 42. In other words, in the high-temperature side circuit 41 of the independent circulation heating mode, there is no inflow or outflow of the heat transfer medium through the heat transfer medium connection flow path 50, and the heat transfer medium circulates independently within the high-temperature side circuit 41.

[0292] Then, with respect to the indoor air conditioning unit 60, the control device 70 determines and controls the airflow capacity of the indoor fan 62, the indoor / outdoor air ratio in the indoor / outdoor air switching device 63, and the ratio of the air mix door 64 according to 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 conditioning system 1 can pump up the heat absorbed from the heat transfer medium by the chiller 21 using the heat pump cycle 10, and use it to heat the blown air in the heater core 43 via the heat transfer medium of the high-temperature side circuit 41. In the low-temperature side circuit 31, heat can be absorbed from the heat absorption source (outdoor air) to the heat transfer medium via the outside air heat exchanger 33, and the heat of the heat transfer medium can be absorbed by the refrigerant circulating in the chiller 21.

[0294] In other words, the independent circulation heating mode according to the fourth embodiment, similar to the heat pump heating mode described above, can draw up the heat absorbed by the heat absorption section 20 on the low-pressure side and use it to heat the object to be heated (blown air) in the heating section 15 on the high-pressure side. The independent circulation heating mode in the fourth embodiment corresponds to an example of the independent circulation heating mode in this disclosure.

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

[0296] The control device 70 compresses and discharges the refrigerant using the compressor 11, and also throttles the low-temperature side expansion valve 19. Therefore, in the heat pump cycle 10 of the circuit-linked heating mode, the refrigerant is switched to a refrigerant circuit that circulates in the following order: compressor 11, heat transfer medium refrigerant heat exchanger 17, low-temperature side expansion valve 19, chiller 21, and compressor 11.

[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 respect to the low-temperature side circuit 31 of the heat transfer medium circuit 30, the control device 70 controls the operation of the three-way valve 34 of the heat transfer medium so that the outlet inlet on the low-temperature side connection part 38 is completely closed, while the outlet inlets on the outside air heat exchanger side and the heat transfer medium bypass flow path 36 are connected.

[0299] Furthermore, the control device 70 controls the operation of the low-temperature side flow rate adjustment unit 37 so as to completely close the inlet and outlet on the bypass connection unit 35 side, while simultaneously connecting the inlet and outlet on the chiller 21 side and the second connection flow path 52 side. The control device 70 then determines the pumping capacity of the low-temperature side pump 32 to a predetermined state for the circuit-linked heating mode.

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

[0301] On the other hand, with respect to the high-temperature side circuit 41 of the heat transfer 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 discharge temperature. At this time, the control device 70 controls the operation of the high-temperature side flow rate adjustment unit 44 so as to connect all inlets and outlets on the first connection flow path 51 side, the heat transfer medium refrigerant heat exchanger 17 side, and the high-temperature side connection unit 45 side.

[0302] As a result, in the high-temperature side circuit 41 of the circuit-linked heating mode, the heat transfer medium is divided into a flow that circulates within the high-temperature side circuit 41 and a flow that connects with the low-temperature side circuit 31 via the heat transfer medium connection flow path 50. In the flow that circulates within the high-temperature side circuit 41, the heat transfer medium circulates in the following order: high-temperature side pump 42, heat transfer medium refrigerant heat exchanger 17, heater core 43, high-temperature side flow rate adjustment unit 44, high-temperature side connection unit 45, and high-temperature side pump 42.

[0303] Then, in the flow that connects with the low-temperature side circuit 31 via the heat transfer medium connection channel 50, a circulation path is configured that passes through the heat transfer medium passage 21b of the chiller 21 via the heat transfer medium connection channel 50, through the control of the low-temperature side flow rate adjustment unit 37 and the high-temperature side flow rate adjustment unit 44 described above. In other words, the heat transfer medium circulates in the following order: high-temperature side pump 42, heat transfer medium refrigerant heat exchanger 17, heater core 43, high-temperature side flow rate adjustment unit 44, first connection channel 51, low-temperature side connection unit 38, chiller 21, low-temperature side flow rate adjustment unit 37, second connection channel 52, and high-temperature side connection unit 45.

[0304] Regarding the indoor air conditioner unit 60 in the circuit cooperation heating mode, the control device 70 determines and controls the blowing capacity of the indoor blower 62, the ratio of the indoor and outdoor air in the indoor / outdoor air switching device 63, and the ratio of the air mix door 64 according to the operating conditions defined for the circuit cooperation heating mode.

[0305] Thus, in the circuit cooperation heating mode according to the fourth embodiment, the vehicle air conditioner 1 can use the heat medium connection flow path 50 and the heat medium flow rate adjustment unit 55 to allow a part of the heat medium team 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 is performed between the heat medium flowing in from the high-temperature side circuit 41 and the low-pressure refrigerant, so the temperature of the low-pressure refrigerant in the heat pump cycle 10 can be increased. As the refrigerant temperature of the low-pressure refrigerant increases, the suction refrigerant density in the compressor 11 also increases, so the work amount of the compressor 11 can be increased, and the heating capacity of the heating object in the circuit cooperation heating mode can be increased. The circuit cooperation heating mode in the fourth embodiment corresponds to an example of the circuit cooperation heating mode in the present disclosure.

[0307] As described above, in the independent circulation heating mode, heat is absorbed from the heat absorption source (outdoor air) through the heat medium of 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 blowing air, which is the heating object, by the heater core 43 through the heat medium of the high-temperature side circuit 41, and the heating of the heating object is realized. Therefore, the heating capacity of the independent circulation heating mode according to the fourth embodiment is affected by the heat absorption amount in the low-temperature side circuit 31, similar to the heat pump heating mode of the above-described embodiment.

[0308] On the other hand, in the circuit cooperation 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 circulation path of the heat medium in the heat medium circuit 30 is different.

[0309] As shown in Figure 15, in the circuit-linked heating mode, a portion of the heat transfer medium that flows out of the refrigerant heat exchanger 17 circulates through the heater core 43 in the high-temperature circuit 41, while the other portion of the heat transfer medium flows through the chiller 21 via the heat transfer medium connection channel 50. In other words, a portion of the heating capacity of the heat transfer medium in the refrigerant heat exchanger 17 is used to heat the object to be heated (blowing air), and the other portion of the heating capacity is used to raise the temperature of the low-pressure refrigerant via the chiller 21.

[0310] Here, it is considered that the heating capacity of the heat transfer medium in the heat transfer 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 at approximately the same level.

[0311] When switching to the circuit-linked heating mode, a portion of the heat transfer medium that flows out of the refrigerant heat exchanger 17 is used to heat the blown air via the heater core 43, while the remaining portion of the heat transfer medium is guided to the chiller 21 via the heat transfer medium connection channel 50 and the heat transfer medium flow rate adjustment unit 55. In other words, since the blown air is heated by a portion of the heat of the heat transfer medium heated by the heat of the high-pressure refrigerant in the heater core 43, it is thought that the heating capacity of the blown air will temporarily decrease immediately after switching from the independent circulation heating mode to the circuit-linked heating mode.

[0312] 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 the difference in operating modes.

[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 in the heat absorption section 20 and the amount of work done by 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 where the low pressure is high in order to increase the amount of work done by the compressor 11 in the circuit-linked heating mode, starting from a low low pressure state required in the independent circulation 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 amount of heat contained in the refrigerant. Therefore, one possible operation in the switching control to increase the low pressure of the heat pump cycle 10 and suppress fluctuations in heating capacity is to reduce the amount of heat dissipated on the high-pressure side of the heat pump cycle 10.

[0315] This reduces the amount of heat dissipated on the high-pressure side of the heat pump cycle 10, allowing the refrigerant discharged from the compressor 11 to retain its heat, thereby increasing the low-pressure level in the heat pump cycle 10. This allows the low-pressure level of the heat pump cycle 10 to be quickly raised to the desired level, and enables the rapid elimination of fluctuations in heating capacity associated with switching operating modes. Hereinafter, the operation that reduces the amount of heat dissipated on the high-pressure side of the heat pump cycle 10 during operating mode switching control will be referred to as the limiting operation.

[0316] Furthermore, as one of the operations in the switching control to suppress fluctuations in heating capacity by increasing the low pressure of the heat pump cycle 10, an operation to maintain the amount of heat absorbed on the low-pressure side of the heat pump cycle 10 as much as possible can be considered.

[0317] As described above, in the independent heating mode before switching, heat absorption occurs in the heat absorption section 20 on the low-pressure side of the heat pump cycle 10 via the heat transfer medium of the heat transfer medium circuit 30. The amount of heat absorbed in the heat absorption section 20 constitutes the amount of heat in 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 in the heat absorption unit 20 is continued from the independent circulation heating mode. However, the switching control when switching operating modes is performed within a range that can maintain the amount of heat absorbed in the heat absorption unit 20, thereby suppressing a decrease in the low-pressure pressure of the heat pump cycle 10. Hereinafter, the operation to maintain as much heat absorption as possible on the low-pressure side of the heat pump cycle 10 during the switching control of operating modes will be referred to as the heat absorption amount securing operation.

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

[0320] In the example shown in Figure 16, the vehicle air conditioning system 1 is operating in independent circulation heating mode from time ta. In the vehicle air conditioning system 1 operating in independent circulation heating mode, the control device 70 controls the operation of the compressor 11, the low-temperature side expansion valve 19, the low-temperature side pump 32, the heat transfer medium three-way valve 34, and the low-temperature side flow rate adjustment unit 37. Furthermore, the control device 70 controls the operation of the high-temperature side pump 42, the high-temperature side flow rate adjustment unit 44, the indoor blower 62, the air mix door 64, etc.

[0321] In the fourth embodiment, at time tb, the switching of the operating mode from independent circulation heating mode to circuit-linked heating mode is determined, and switching control in the vehicle air conditioning system 1 is started. The conditions for starting the switching control include, for example, when the amount of heat absorbed from the heat absorption unit 20 is insufficient to meet the required heating capacity, and the independent circulation heating mode cannot meet the required heating capacity. The relationship between the required heating capacity and the amount of heat absorbed is determined based on the relationship between the target outlet temperature of the conditioned air and the temperature of the heat absorbed object (air) in the heat absorption unit 20.

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

[0323] The rotational speed of the compressor 11 is adjusted from the rotational speed in the independent circulation heating mode to a predetermined rotational speed determined in the switching control. The throttle opening of the 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 a predetermined throttle opening determined in the switching control is maintained.

[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, which constitute the heat transfer medium flow rate adjustment unit 55, to allow the heat transfer 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 switching control, the heat pump cycle 10 is switched to a refrigerant circuit similar to that of the independent circulation heating mode, although the refrigerant discharge capacity of the compressor 11 and the amount of pressure reduction at the low-temperature side expansion valve 19 are different.

[0326] During switching control, the heat transfer medium circuit 30 continues to circulate the heat transfer medium in the low-temperature circuit 31 and the high-temperature circuit 41 in the independent circulation heating mode, while allowing the heat transfer medium to flow in and out through the heat transfer medium connection channel 50.

[0327] As a result, in the high-temperature circuit 41, a portion of the heat transfer medium heated by the heat of the high-pressure refrigerant flows into the low-temperature circuit 31 via the second connecting channel 52 and is heated by the low-pressure refrigerant in the chiller 21. Therefore, the operation of allowing the inflow and outflow of the heat transfer medium between the low-temperature circuit 31 and the high-temperature circuit 41 via the heat transfer medium connecting channel 50 while the heat absorption section 20 is continuously absorbing heat from the independent circulation heating mode is an example of an operation to ensure the amount of heat absorbed.

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

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

[0330] In other words, in switching control, the amount of heat supplied to the heater core 43 constituting the heating unit 15 (blown air) is limited by the operation control of the indoor blower 62. Therefore, in switching control, limiting the blowing capacity of the indoor blower 62 to a lower level than in independent circulation heating mode is an example of a limiting operation in switching control, as it limits the destination of heat dissipation from the high-pressure refrigerant.

[0331] Furthermore, the opening of the air mix door 64 is controlled to a predetermined value such that the opening of the cold air bypass passage 65 is greater than in the independent circulation heating mode. In other words, during the switching operation, the air mix door 64 is controlled so that most of the air that has passed through the cooler core 33a flows around the heater core 43.

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

[0333] Thus, once time tb has elapsed and the operation control of each component related to the switching control has been performed, the high-pressure refrigerant pressure in the heat pump cycle 10 decreases. In Figure 16, the completion time of the various operations in the switching control is shown as time tc.

[0334] After time tc, while the switching control continues, the limiting operation and heat absorption amount securing operation described above also continue to be performed. In the fourth embodiment as well, in the switching control, the state in which the limiting operation and heat absorption amount securing operation are performed in parallel is referred to as the first state of the switching control.

[0335] Furthermore, because the limiting operation restricts 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 increases over time from the start of the limiting operation. In other words, 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 securing operation, the amount of heat absorbed in the heat absorption section 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 transfer medium heated by the heat of the high-pressure refrigerant is directly introduced into the heat transfer medium passage 21b of the chiller 21 via the heat transfer medium connection flow path 50.

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

[0338] As a switching control, if the limiting operation and heat absorption amount securing operation are continued from time tc, the refrigerant temperature in the refrigerant passage 21a of the chiller 21 will reach a predetermined reference chiller side temperature KTc. The refrigerant temperature in the refrigerant passage 21a of the chiller 21 being equal to or above the predetermined reference chiller side temperature KTc is one example of a heat absorption stop condition.

[0339] In the fourth embodiment, time tdx is defined as the point in 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 met. Since time tdx is reached, it is the point in time when the amount of heat absorbed in the heat absorption section 20 can no longer be sufficiently secured, and even if the heat absorption amount securing operation is performed, it is difficult to raise the low-pressure refrigerant using the absorbed heat.

[0340] In the heat absorption securing operation of the fourth embodiment, in addition to heat absorption using the outdoor air as a heat absorption source, as in the embodiments described above, heat absorption is also performed from the heat transfer medium flowing in from the high-temperature side circuit 41. By utilizing the heat transfer medium from the high-temperature side circuit 41, it becomes easier to further raise 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 embodiments described above.

[0341] After time tdx has elapsed, the heat absorption amount securing operation is terminated. Specifically, with respect to heat absorption in the heat absorption section 20 in the switching control, heat absorption from the outside air is stopped. For example, the operation of the heat transfer medium three-way valve 34 is controlled to completely close the inlet and outlet on the low-temperature side connection section 38 side, while simultaneously connecting the inlet and outlet on the outside air heat exchanger 33 side and the heat transfer medium bypass flow path 36 side. Then, the operation of the low-temperature side flow rate adjustment section 37 is controlled to completely close the inlet and outlet on the bypass connection section 35 side, while simultaneously connecting the inlet and outlet on the chiller 21 side and the second connection flow path 52 side.

[0342] As a result, the circulation path of the heat transfer medium in the low-temperature circuit 31 is switched to a circulation path that goes through the outside air heat exchanger 33 and the heat transfer medium bypass channel 36, and does not go through the chiller 21, so that heat absorption from the outside air, which is the heat absorption source, is stopped. Alternatively, it is also possible to stop the low-temperature pump 32 in order to stop heat absorption from the heat absorption source.

[0343] By stopping the heat absorption operation as soon as the heat absorption stop conditions are met, the waste of energy required for the heat absorption operation can be suppressed, resulting in energy-efficient switching control.

[0344] Even after the heat absorption amount securing operation is completed, the circulation and limiting of the refrigerant and heat transfer medium in the heat pump cycle 10 under switching control continues. This state is called the second state of switching control. In the second state of switching control, because the limiting operation continues to be performed, the high-pressure pressure, low-pressure pressure, and low-pressure side refrigerant temperature of the refrigerant in the heat pump cycle 10 continue to rise with the passage of time, even after the completion of the heat absorption amount securing operation and the time tdx.

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

[0346] Specifically, it is determined whether the high-pressure refrigerant pressure in the heat pump cycle 10 under switching control has risen above 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 achieve the same heating capacity as the independent circulation heating mode, thereby suppressing fluctuations in heating capacity.

[0347] Another method to suppress fluctuations in heating capacity when switching to the circuit-linked heating mode is to increase the workload of the compressor 11 to a state equivalent to the heating capacity in the independent circulation heating mode during the second state of switching control. That is, during the second state of switching control, it is determined whether or not the low pressure of the refrigerant in the heat pump cycle 10 has become higher than the reference low 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 work done by the compressor 11 in the circuit-linked heating mode is equivalent to the heating capacity of the independent circulation heating mode. If 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 achieve the same heating capacity as the independent circulation heating mode, thereby suppressing fluctuations in heating capacity.

[0349] As shown in Figure 16, after time tdx has elapsed and the system has transitioned to the second state of switching control, the high-pressure and low-pressure in the heat pump cycle 10 gradually increase. Time te is defined as the point at which either the high-pressure in the heat pump cycle 10 becomes equal to or greater than the reference high-pressure KPd, or the low-pressure in the heat pump cycle 10 becomes equal to or greater than the reference low-pressure KPs.

[0350] Note that the example shown in Figure 16 shows a case where the high pressure of the heat pump cycle 10 becomes equal to or greater than the reference high pressure KPd and the low pressure of the heat pump cycle 10 becomes equal to or greater than the reference low pressure KPs, both occurring simultaneously. However, this is just one example. The time te may be defined as the point in time when either of the two conditions described above is met first. Furthermore, considering the need to reliably suppress fluctuations in heating capacity, the time te may be defined as the point in time when both the high pressure condition and the low pressure condition are met.

[0351] When the conditions for the high-pressure side or low-pressure side of the refrigerant in the heat pump cycle 10 are met and time te has elapsed, the switching control ends and the system switches to the circuit-linked heating mode. By ending the limiting operation and switching to the circuit-linked heating mode, provided that the conditions for the high-pressure side of the refrigerant are met, the heating capacity of the heat pump cycle 10 reaches a predetermined level (i.e., the level before the switching control), and the circuit-linked heating mode is started. This allows the execution of the circuit-linked heating mode to begin while suppressing fluctuations in the heating capacity of the blown air, which is the object to be heated.

[0352] Furthermore, provided that the conditions for the low-pressure side of the refrigerant are met, the limiting operation ends and the system switches to the circuit-linked heating mode. This starts the circuit-linked heating mode when the workload of the compressor 11 reaches a predetermined level (i.e., the level before switching control). In this case as well, 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] Thus, according to the fourth embodiment, when switching from the independent circulation heating mode to the circuit-linked heating mode, switching control is performed to execute a limiting operation, allowing 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 operating modes while suppressing the difference in heating capacity caused by the configuration of the refrigerant circuits in the independent circulation heating mode and the circuit-linked heating mode.

[0354] As shown in Figure 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 that constitutes the heating unit 15. By limiting the amount of air supplied by the indoor blower 62, the amount of heat dissipated on the high-pressure side of the heat pump cycle 10 can be limited, thereby improving the heating capacity on the high-pressure side of the heat pump cycle 10.

[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 blown air supplied to the heater core 43 that constitutes the heating unit 15. The operation of the air mix door 64 allows for limiting the amount of blown air supplied to the heater core 43 in terms of the airflow path of the object to be heated. Therefore, the limiting operation related to the operation control of the air mix door 64 ensures that the heating capacity of the heat pump cycle 10 is sufficiently secured before transitioning to the circuit-linked heating mode.

[0356] As shown in Figure 16, in switching control, the limiting operation and the heat absorption amount securing operation are performed in parallel. In other words, by performing the limiting operation and the heat absorption amount securing operation in parallel, it is possible to utilize both the perspective of heating capacity on the high-pressure side of the heat pump cycle 10 and the perspective of the amount of work 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 fluctuation can be kept to a minimum.

[0357] In the fourth embodiment, the heat absorption amount is secured by absorbing heat from a heat transfer medium flowing in from the high-temperature side circuit 41 via the heat transfer medium connection channel 50, in parallel with the operation of the chiller 21 absorbing heat from a heat absorption source (outdoor air) for the low-pressure refrigerant, similar to independent circulation heating. As a result, in addition to the heat absorption source (outdoor air), a portion of the heat from the discharged refrigerant discharged from the compressor 11 can be utilized, 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 in the time tdx in Figure 16, the heat absorption maintenance operation in switching control is terminated when the heat absorption stop condition is met and the heat absorption amount falls below a predetermined standard. In other words, by efficiently executing the heat absorption maintenance operation in switching control, fluctuations in heating capacity can be suppressed.

[0359] Furthermore, as shown in Figure 16, when the heat absorption amount securing operation is being performed and the heat absorption stop condition is met, the supply amount of heat transfer fluid circulating in the low-temperature side circuit 31 to the chiller 21 is set to 0. Specifically, the circulation path of the heat transfer fluid in the low-temperature side circuit 31 is switched, excluding the heat transfer fluid passage 21b of the chiller 21, and switching to a circulation path that goes through the outside air heat exchanger 33 and the heat transfer fluid bypass passage 36. This allows the heat absorption amount securing operation to be terminated with simple operation control.

[0360] As described above, according to the vehicle air conditioning system 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 radiated by the heater core 43 that constitutes the heating unit 15. By performing a limiting operation in the switching control, the heating capacity on 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 suppressed to a small extent.

[0361] As shown in Figure 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 that constitutes the heating unit 15. By limiting the amount of air supplied by the indoor blower 62, the amount of heat dissipated on the high-pressure side of the heat pump cycle 10 can be limited, thereby improving the heating capacity on the high-pressure side of the heat pump cycle 10.

[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 blown air supplied to the heater core 43 that constitutes the heating unit 15. The operation of the air mix door 64 limits the amount of blown air supplied to the heater core 43 in terms of the airflow path of the object to be heated. Therefore, the limiting operation related to the operation control of the air mix door 64 ensures that the heating capacity of the heat pump cycle 10 is sufficiently secured before transitioning to the circuit-linked heating mode.

[0363] As shown in Figure 16 from time tc to time te, the limiting operation in switching control releases the heat dissipation limit when the high pressure of the heat pump cycle 10 becomes equal to or greater than the reference high pressure KPd. The state in which the high pressure becomes equal to or greater than the reference high pressure indicates that the heating capacity of the heat pump cycle 10 has improved to a predetermined standard. Therefore, from the perspective of the heating capacity of the heat pump cycle 10, the limiting operation can be terminated when fluctuations in 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 heat dissipation limit when the low pressure of the heat pump cycle 10 becomes equal to or greater than the reference low pressure KPs. The state in which the low pressure becomes equal to or greater than the reference low pressure indicates that the workload of the compressor 11 has increased to a predetermined standard. Therefore, from the perspective of the workload of the compressor 11, the limiting operation can be terminated when fluctuations in heating capacity can be suppressed, and the system can transition to the circuit-linked heating mode.

[0365] As shown in Figure 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 securing operation are performed in parallel before transitioning to the circuit-linked heating mode. The limiting operation improves the heating capacity of the heat pump cycle 10, while the heat absorption amount securing operation increases the workload of the compressor 11. Therefore, by performing the limiting operation and the heat absorption amount securing operation in parallel, the required period for switching control can be shortened, and fluctuations in heating capacity can be suppressed in a short period of time.

[0366] This disclosure is not limited to the embodiments described above, and can be modified in various ways without departing from the spirit of this disclosure, as follows.

[0367] In the embodiments described above, the heat pump cycle device according to this disclosure is applied to a vehicle air conditioning system 1 installed in an electric vehicle, but the invention is not limited to this embodiment. For example, the object to be heated in the heat pump cycle device according to this disclosure is not limited to the blown air that is the target of air conditioning. That is, the heat pump cycle device according to this disclosure may be applied to a water heater in which the object to be heated is, for example, water.

[0368] Furthermore, while the embodiments described above mentioned outdoor air, heat transfer fluid, etc., as the heat absorbed object and heat absorbed source in the heat pump cycle device, the invention is not limited to these embodiments. For example, waste heat from equipment mounted on an electric vehicle may be used as the heat absorbed source, or waste heat generated in a battery, inverter, PCU, transaxle, ADAS control device, etc., may be used as the heat absorbed source.

[0369] An inverter supplies power to motor generators and other components. A PCU is a power control unit that performs power transformation and distribution. A transaxle is a power transmission mechanism that integrates components such as the transmission and differential gear. An ADAS control unit is a control unit for advanced driver-assistance systems.

[0370] In the configuration of the heating unit 15 of the embodiment described above, there are configurations that directly dissipate the heat of the high-pressure refrigerant to the object to be heated, such as the indoor condenser 16, and configurations that indirectly dissipate the heat of the high-pressure refrigerant to the object to be heated, such as the heat transfer medium refrigerant heat exchanger 17 and the high-temperature side circuit 41. In other words, the heating unit 15 only needs to ensure that the heat of the high-pressure refrigerant is ultimately used to heat the object to be heated, and does not limit the state of the refrigerant along the way to the object to be heated.

[0371] Furthermore, while the above-described embodiments mentioned a configuration of the heat absorption section 20 having a chiller 21, a configuration having an outside air heat absorber 22, and a configuration having both a chiller 21 and an outside air heat absorber 22, the configuration is not limited to these embodiments. The heat absorption section 20 only needs to be capable of absorbing heat from a heat absorption source, and may be composed of more heat absorbers.

[0372] In the embodiment described above, the termination conditions for the limiting operation are given as when the high pressure becomes equal to or greater than the reference high pressure KPd, and when the low pressure becomes equal to or greater than the reference low pressure KPs. The reference high pressure KPd and reference low pressure KPs are determined considering the application of the vehicle air conditioning system 1. That is, the reference high pressure KPd and reference low pressure KPs are determined so that the change in heating capacity before and after switching is such that the occupants do not feel a significant discomfort.

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

[0374] The features of the heat pump cycle apparatus disclosed herein are as follows: (Item 1) A compressor (11) that compresses and discharges the refrigerant, A branching section (12a) that branches the flow of the refrigerant discharged from the compressor, A heating unit (15) that heats an object to be heated using the refrigerant that has flowed out from one of the outlets of the branching section as a heat source, A low-temperature side pressure reduction section (19, 26, 27) for reducing the pressure of the refrigerant that has leaked out from the heating section, A bypass passage (13) for circulating the other refrigerant branched off at the aforementioned branching point, A bypass-side pressure reducing unit (14) that adjusts the flow rate of the refrigerant flowing through the bypass passage, A confluence section (12b, 25) combines the flow of the refrigerant discharged from the bypass-side pressure reduction section and the flow of the refrigerant discharged from the low-temperature-side pressure reduction section and discharges them towards the compressor's intake side, A heat absorption section (20) that causes the heat possessed by the object to be heated to be absorbed by the refrigerant that has flowed out from at least the low-temperature side reduced pressure section, A first heating mode in which all of the refrigerant discharged from the compressor is flowed into the heating section via the branching section, and the heat absorbed from the object to be heated is drawn up in the heat absorption section to heat the object to be heated, The system includes a control unit (70) that controls switching to a second heating mode in which a portion of the refrigerant discharged from the compressor is allowed to flow into the bypass passage via the branching section, guiding the refrigerant flowing out from the bypass-side pressure reduction section to the confluence section, and the remaining portion of the refrigerant discharged from the compressor is allowed to flow into the heating section via the branching section, and the refrigerant flowing out from the heating section is combined with the flow of refrigerant from the bypass-side pressure reduction section at the confluence section and drawn into the compressor. The control unit, when switching from the first heating mode to the second heating mode, performs a limiting operation to reduce the amount of heat dissipated in the heating section of the first heating mode, and after performing the limiting operation, completes the switch to the second heating mode in the heat pump cycle device. (Item 2) The heating unit includes a heat sink (16) that dissipates the heat of the refrigerant that flows into the heating unit, and a supply adjustment unit (62, 64) that adjusts the amount of the object to be heated supplied to the heat sink. The heat pump cycle apparatus according to item 1, wherein the limiting operation controls the operation of the supply adjustment unit to limit the amount of the material to be heated to the heat sink to a predetermined standard 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 dissipated in the heating unit when the heating capacity of the heating unit exceeds a predetermined standard 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 dissipated in 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 performs a heat absorption amount securing operation in parallel with the limiting operation, which secures the amount of heat absorbed in the heat absorption section by using the heat of the refrigerant discharged from the compressor and the heat absorbed from the object to be heated in the heat absorption section. A heat pump cycle device according to any one of items 1 to 4, which completes the switching to the second heating mode after performing the heat absorption amount securing operation and the limiting operation. (Item 6) A compressor (11) that compresses and discharges the refrigerant, A branching section (12a) that branches the flow of the refrigerant discharged from the compressor, A heating unit (15) that heats an object to be heated using the refrigerant that has flowed out from one of the outlets of the branching section as a heat source, A low-temperature side pressure reduction section (19, 26, 27) for reducing the pressure of the refrigerant that has leaked out from the heating section, A bypass passage (13) for circulating the other refrigerant branched off at the aforementioned branching point, A bypass-side pressure reducing unit (14) that adjusts the flow rate of the refrigerant flowing through the bypass passage, A confluence section (12b, 25) combines the flow of the refrigerant discharged from the bypass-side pressure reduction section and the flow of the refrigerant discharged from the low-temperature-side pressure reduction section and discharges them towards the compressor's intake side, A heat absorption section (20) that causes the heat possessed by the object to be absorbed to be absorbed by the refrigerant that has flowed out from at least the low-temperature side reduced pressure section, A first heating mode in which all of the refrigerant discharged from the compressor is flowed into the heating section via the branching section, and the heat absorbed from the object to be heated is drawn up in the heat absorption section to heat the object to be heated, The system includes a control unit (70) that controls switching to a second heating mode in which a portion of the refrigerant discharged from the compressor is allowed to flow into the bypass passage via the branching section, guiding the refrigerant flowing out from the bypass-side pressure reduction section to the confluence section, and the remaining portion of the refrigerant discharged from the compressor is allowed to flow into the heating section via the branching section, and the refrigerant flowing out from the heating section is combined with the flow of refrigerant from the bypass-side pressure reduction section at the confluence section and drawn into the compressor. The control unit, when switching from the first heating mode to the second heating mode, performs a heat absorption amount securing operation to ensure the amount of heat absorbed in the heat absorption section by using the heat of the refrigerant discharged from the compressor and the heat absorbed from the heat absorption target in the heat absorption section, and after performing the heat absorption amount securing operation, completes the switch to the second heating mode. (Item 7) The aforementioned heat absorption amount securing operation, while operating in the first heating mode, continues to absorb heat from the object to be heated by the heat absorption unit, The heat pump cycle apparatus according to item 6, wherein a portion of the refrigerant discharged from the compressor is allowed to flow into the bypass passage via the branching section, and the refrigerant flowing out from the bypass-side pressure reduction section is guided to the confluence section. (Item 8) The control unit suppresses heat absorption in the heat absorption section when the heat absorption amount securing operation is being performed, if the amount of heat absorbed from the object to be absorbed to the refrigerant in the heat absorption section is lower than a predetermined standard amount of heat absorbed (KTc), thus fulfilling the heat absorption stop condition. (Item 9) The heat pump cycle apparatus according to item 8, wherein the control unit reduces the amount of the heat absorbed object supplied to the heat absorbed section when the heat absorption stop condition is met while the heat absorption amount securing operation is being performed, thereby suppressing heat absorption in the heat absorbed section. (Item 10) The system has a refrigerant bypass channel connected to guide the flow of the refrigerant that has flowed out from the heating section to the confluence section, bypassing the heat absorption section (21). The heat pump cycle device according to item 8, wherein the control unit, when the heat absorption amount securing operation is being performed and the heat absorption stop condition is met, uses the refrigerant bypass flow path to stop the supply of the refrigerant to the heat absorption unit (21), thereby suppressing heat absorption in the heat absorption unit. (Item 11) A heat pump cycle (10) comprising: a compressor (11) that compresses and discharges a refrigerant; a heat transfer medium refrigerant heat exchanger (17) that dissipates the heat of the high-pressure refrigerant discharged from the compressor into a heat transfer medium; a pressure reducing unit (19) that reduces the pressure of the refrigerant flowing out of the heat transfer medium refrigerant heat exchanger; and a chiller (21) that causes the refrigerant to absorb heat by exchanging heat between the refrigerant reduced in pressure by the pressure reducing unit and the heat transfer medium. A heat transfer medium circuit (30) includes: a first circuit (41) which includes a heat transfer medium radiator (43) configured to allow the heat transfer medium that has flowed out of the heat transfer medium refrigerant heat exchanger to circulate and to release the heat of the heat transfer medium to an object to be heated; a second circuit (31) which has a heat transfer medium absorber (33) configured to allow the heat transfer medium flowing through the chiller to circulate and to absorb heat from an object to be heated by heat exchange with the heat transfer medium; a heat transfer medium connection channel (50) which is connected between the first circuit and the second circuit so that the heat transfer medium can flow in and out; and a flow rate adjustment unit (55) which adjusts the flow rate of the heat transfer medium flowing in and out between the first circuit and the second circuit via the heat transfer medium connection channel. An independent circulation heating mode is provided, in which heat originating from the object to be heated is absorbed and pumped up from the heat transfer medium circulating independently in the second circuit, and the object to be heated is heated in the heat transfer medium radiator via the heat transfer medium circulating independently in the first circuit, The system includes a control unit (70) that controls switching to a circuit-linked heating mode in which a portion of the heat transfer medium that has flowed through the heat transfer medium refrigerant heat exchanger is circulated through the chiller via the heat transfer medium connection channel, and another portion of the heat transfer medium that has flowed through the heat transfer medium refrigerant heat exchanger is circulated through the first circuit via the heat transfer medium radiator, thereby heating the object to be heated in the heat transfer medium radiator. The control unit, when switching from the independent circulation heating mode to the circuit-coordinated heating mode, performs a limiting operation to reduce the amount of heat dissipated in the heat transfer fluid radiator in the independent circulation heating mode, and after performing the limiting operation, completes the switch to the circuit-coordinated heating mode in the heat pump cycle device. (Item 12) It has a supply adjustment unit (62, 64) that adjusts the amount of the object to be heated supplied to the heat transfer medium radiator, The heat pump cycle apparatus according to item 11, wherein the limiting operation controls the operation of the supply adjustment unit to limit the amount of the object to be heated to the heat transfer fluid radiator to a predetermined standard 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 dissipated in the heat transfer fluid radiator when the heating capacity of the heat transfer fluid circulating in the first circuit exceeds a predetermined standard (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 dissipated in the heat transfer fluid radiator when the pressure of the refrigerant in the chiller exceeds a predetermined reference low pressure (KPs) while the limiting operation is being performed. (Item 15) When the control unit switches from the independent circulation heating mode to the circuit-cooperative heating mode, it performs a heat absorption amount securing operation in parallel with the limiting operation, which secures the amount of heat absorbed in the chiller by using the heat absorbed from the object to be heated by the heat absorber and the heat of the heat absorber that is guided from the first circuit to the chiller via the heat absorber connection channel. A heat pump cycle device according to any one of items 11 to 14, which completes the switching to the circuit-linked heating mode after performing the heat absorption amount securing operation and the limiting operation.

[0375] This disclosure is described in accordance with the embodiments, but it is understood that this disclosure is not limited to such embodiments or structures. This disclosure also includes various modifications and variations within the equivalence. In addition, various combinations and forms, as well as other combinations and forms that include only one, more, or fewer of those elements, fall within the scope and concept of this disclosure.

Claims

1. A compressor (11) that compresses and discharges the refrigerant, A branching section (12a) that branches the flow of the refrigerant discharged from the compressor, A heating unit (15) that heats an object to be heated using the refrigerant that has flowed out from one of the outlets of the branching section as a heat source, A low-temperature side pressure reduction section (19, 26, 27) for reducing the pressure of the refrigerant that has flowed out from the heating section, A bypass passage (13) for circulating the other refrigerant branched off at the aforementioned branching point, A bypass-side pressure reducing unit (14) that adjusts the flow rate of the refrigerant flowing through the bypass passage, A confluence section (12b, 25) combines the flow of the refrigerant discharged from the bypass-side pressure reduction section and the flow of the refrigerant discharged from the low-temperature-side pressure reduction section and discharges them towards the compressor's intake side, A heat absorption section (20) that causes the heat possessed by the object to be heated to be absorbed by the refrigerant that has flowed out from at least the low-temperature side reduced pressure section, A first heating mode in which all of the refrigerant discharged from the compressor is flowed into the heating section via the branching section, and the heat absorbed from the object to be heated is drawn up in the heat absorption section to heat the object to be heated, The system includes a control unit (70) that controls switching to a second heating mode in which a portion of the refrigerant discharged from the compressor is allowed to flow into the bypass passage via the branching section, guiding the refrigerant flowing out from the bypass-side pressure reduction section to the confluence section, and the remaining portion of the refrigerant discharged from the compressor is allowed to flow into the heating section via the branching section, and the refrigerant flowing out from the heating section is combined with the flow of refrigerant from the bypass-side pressure reduction section at the confluence section and drawn into the compressor. The control unit, when switching from the first heating mode to the second heating mode, performs a limiting operation to reduce the amount of heat dissipated in the heating section of the first heating mode, and after performing the limiting operation, completes the switch to the second heating mode in the heat pump cycle device.

2. The heating unit includes a heat sink (16) that dissipates the heat of the refrigerant that flows into the heating unit, and a supply adjustment unit (62, 64) that adjusts the amount of the object to be heated supplied to the heat sink. The heat pump cycle apparatus according to claim 1, wherein the limiting operation controls the operation of the supply adjustment unit to limit the amount of the material to be heated to the heat sink to a predetermined standard amount.

3. The heat pump cycle apparatus according to claim 1, wherein the control unit terminates the limiting operation and releases the limit on the amount of heat dissipated in the heating unit when the heating capacity of the heating unit exceeds a predetermined standard heating capacity (KPd) while the limiting operation is being performed.

4. The heat pump cycle apparatus according to claim 1, wherein the control unit terminates the limiting operation and releases the limit on the amount of heat dissipated in 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.

5. When switching from the first heating mode to the second heating mode, the control unit performs a heat absorption amount securing operation in parallel with the limiting operation, which secures the amount of heat absorbed in the heat absorption section by using the heat of the refrigerant discharged from the compressor and the heat absorbed from the object to be heated in the heat absorption section. A heat pump cycle device according to any one of claims 1 to 4, wherein after performing the heat absorption amount securing operation and the limiting operation, the switching to the second heating mode is completed.

6. A compressor (11) that compresses and discharges the refrigerant, A branching section (12a) that branches the flow of the refrigerant discharged from the compressor, A heating unit (15) that heats an object to be heated using the refrigerant that has flowed out from one of the outlets of the branching section as a heat source, A low-temperature side pressure reduction section (19, 26, 27) for reducing the pressure of the refrigerant that has flowed out from the heating section, A bypass passage (13) for circulating the other refrigerant branched off at the aforementioned branching point, A bypass-side pressure reducing unit (14) that adjusts the flow rate of the refrigerant flowing through the bypass passage, A confluence section (12b, 25) combines the flow of the refrigerant discharged from the bypass-side pressure reduction section and the flow of the refrigerant discharged from the low-temperature-side pressure reduction section and discharges them towards the compressor's intake side, A heat absorption unit (20) that causes the heat possessed by the object to be heated to be absorbed by the refrigerant that has flowed out from at least the low-temperature side reduced pressure section, A first heating mode in which all of the refrigerant discharged from the compressor is flowed into the heating section via the branching section, and the heat absorbed from the object to be heated is drawn up in the heat absorption section to heat the object to be heated, The system includes a control unit (70) that controls switching to a second heating mode in which a portion of the refrigerant discharged from the compressor is allowed to flow into the bypass passage via the branching section, guiding the refrigerant flowing out from the bypass-side pressure reduction section to the confluence section, and the remaining portion of the refrigerant discharged from the compressor is allowed to flow into the heating section via the branching section, and the refrigerant flowing out from the heating section is combined with the flow of refrigerant from the bypass-side pressure reduction section at the confluence section and drawn into the compressor. The control unit, A heat pump cycle device that, when switching from the first heating mode to the second heating mode, performs a heat absorption amount securing operation to ensure the amount of heat absorbed in the heat absorption section by using the heat of the refrigerant discharged from the compressor and the heat absorbed from the object to be heated in the heat absorption section, and after performing the heat absorption amount securing operation, completes the switch to the second heating mode.

7. The aforementioned heat absorption amount securing operation, while operating in the first heating mode, continues to absorb heat from the object to be heated by the heat absorption unit, The heat pump cycle apparatus according to claim 6, wherein a portion of the refrigerant discharged from the compressor is allowed to flow into the bypass passage via the branching section, and the refrigerant flowing out from the bypass-side pressure reduction section is guided to the confluence section.

8. The heat pump cycle device according to claim 6, in which the control unit suppresses heat absorption in the heat absorption section when the heat absorption amount securing operation is being performed and the amount of heat absorbed from the object to be absorbed to the refrigerant in the heat absorption section is lower than a predetermined standard amount of heat absorbed (KTc), thus satisfying the heat absorption stop condition.

9. The heat pump cycle apparatus according to claim 8, wherein the control unit reduces the amount of the heat absorbed object supplied to the heat absorbed section when the heat absorption stop condition is met while the heat absorption amount securing operation is being performed, thereby suppressing heat absorption in the heat absorbed section.

10. The system has a refrigerant bypass channel connected to guide the flow of the refrigerant that has flowed out from the heating section to the confluence section, bypassing the heat absorption section (21). The heat pump cycle device according to claim 8, wherein the control unit, when the heat absorption amount securing operation is being performed and the heat absorption stop condition is met, stops supplying the refrigerant to the heat absorption unit (21) using the refrigerant bypass flow path, thereby suppressing heat absorption in the heat absorption unit.

11. A heat pump cycle (10) comprising: a compressor (11) that compresses and discharges a refrigerant; a heat transfer medium refrigerant heat exchanger (17) that dissipates the heat of the high-pressure refrigerant discharged from the compressor into a heat transfer medium; a pressure reducing unit (19) that reduces the pressure of the refrigerant flowing out of the heat transfer medium refrigerant heat exchanger; and a chiller (21) that causes the refrigerant to absorb heat by exchanging heat between the refrigerant reduced in pressure by the pressure reducing unit and the heat transfer medium. A heat transfer medium circuit (30) includes: a first circuit (41) which includes a heat transfer medium radiator (43) configured to allow the heat transfer medium that has flowed out of the heat transfer medium refrigerant heat exchanger to circulate and to release the heat contained in the heat transfer medium to an object to be heated; a second circuit (31) which has a heat transfer medium absorber (33) configured to allow the heat transfer medium flowing through the chiller to circulate and to absorb heat from an object to be heated by heat exchange with the heat transfer medium; a heat transfer medium connection channel (50) which is connected between the first circuit and the second circuit so that the heat transfer medium can flow in and out; and a flow rate adjustment unit (55) which adjusts the flow rate of the heat transfer medium flowing in and out between the first circuit and the second circuit via the heat transfer medium connection channel. An independent circulation heating mode in which heat is absorbed from the heat transfer medium circulating independently in the second circuit, heat originating from the object to be heated is drawn up, and the object to be heated is heated in the heat transfer medium radiator via the heat transfer medium circulating independently in the first circuit, The system includes a control unit (70) that controls switching to a circuit-linked heating mode in which a portion of the heat medium that has flowed through the heat medium refrigerant heat exchanger is circulated through the chiller via the heat medium connection channel, and another portion of the heat medium that has flowed 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 in the heat medium radiator. The control unit, when switching from the independent circulation heating mode to the circuit-coordinated heating mode, performs a limiting operation to reduce the amount of heat dissipated in the heat transfer fluid radiator in the independent circulation heating mode, and after performing the limiting operation, completes the switch to the circuit-coordinated heating mode in the heat pump cycle device.

12. It has a supply adjustment unit (62, 64) that adjusts the amount of the object to be heated supplied to the heat transfer medium radiator, The heat pump cycle apparatus according to claim 11, wherein the limiting operation controls the operation of the supply adjustment unit to limit the amount of the object to be heated to the heat transfer medium radiator to a predetermined standard amount.

13. The heat pump cycle apparatus according to claim 11, wherein the control unit terminates the limiting operation and releases the limit on the amount of heat dissipated in the heat transfer fluid radiator when the heating capacity of the heat transfer fluid circulating in the first circuit exceeds a predetermined standard (KPd) while the limiting operation is being performed.

14. The heat pump cycle apparatus according to claim 11, wherein the control unit terminates the limiting operation and releases the limit on the amount of heat dissipated in the heat transfer fluid 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. When the control unit switches from the independent circulation heating mode to the circuit-cooperative heating mode, it performs a heat absorption amount securing operation in parallel with the limiting operation, which secures the amount of heat absorbed in the chiller by using the heat absorbed from the object to be heated by the heat absorber and the heat of the heat absorber guided from the first circuit to the chiller via the heat absorber connection channel. A heat pump cycle device according to any one of claims 11 to 14, wherein after performing the heat absorption amount securing operation and the limiting operation, the switching to the circuit linked heating mode is completed.

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