Vehicle air conditioner

Abstract

[Problem] To provide a vehicle air conditioner in which it is possible to avoid a drop in intake density of a refrigerant in a compressor and extend a service life of the compressor while improving quick heating performance. [Solution] A bypass pathway, by which a refrigerant having passed through a compressor 11 bypasses a heater core 12 to flow into an intake side 11b of the compressor 11, comprises: a first pathway in which the refrigerant having passed through the compressor 11 flows toward the upstream side of an accumulator 15; and a second pathway in which the refrigerant having passed through the compressor 11 flows to the downstream side of the accumulator 15.

Description

Vehicle air conditioning system

[0001] The present invention relates to an air conditioning system for a vehicle.

[0002] Air conditioners using heat pumps are known as air conditioners for electric vehicles (EVs) that do not have a combustion-based heat source such as an engine, or for vehicles with a low heat output from a combustion-based heat source. However, air conditioners using heat pumps have difficulty absorbing heat from outside air when the outside temperature is extremely low, resulting in reduced heating efficiency. For this reason, for example, Patent Document 1 discloses a technology that employs a heating method known as hot gas heating, which utilizes the heat pump's compressor when the outside temperature is extremely low.

[0003] JP 2023-075844 A

[0004] SUMMARY OF THE INVENTION An object of the present invention is to provide a vehicle air conditioner that can improve the quick heating performance, prevent a decrease in the suction density of the refrigerant in the compressor, and extend the life of the compressor.

[0005] According to one aspect of the present invention, there is provided a vehicle air conditioning system including a refrigerant circuit configured to circulate through a compressor, a heater core that heats air supplied to a vehicle cabin, a pressure reducing device, a low-temperature side heat exchanger that causes a refrigerant to absorb heat from a heat medium that has absorbed heat from an on-board heat-generating device, and an accumulator, the refrigerant circuit including a bypass path that causes the refrigerant that has passed through the compressor to bypass the heater core and flow into the suction side of the compressor, and a control device that is controllable to a hot gas heating mode in which a portion of the refrigerant that has passed through the compressor flows to the heater core and the remaining refrigerant flows to the bypass path, the bypass path including a first path through which the refrigerant that has passed through the compressor flows upstream of the accumulator, and a second path through which the refrigerant that has passed through the compressor flows downstream of the accumulator.

[0006] According to the present invention, it is possible to provide a vehicle air conditioner that can improve the quick heating performance, avoid a decrease in the suction density of the refrigerant in the compressor, and extend the life of the compressor.

[0007] FIG. 1 is a diagram showing an outline of an exemplary configuration of a vehicle air conditioner according to a first embodiment, and is a diagram showing an example of the state of the vehicle air conditioner when hot gas heating is performed. FIG. 2 is a diagram showing an example of a block diagram of a control device in a vehicle air conditioner according to the first embodiment and the second embodiment. FIG. 3 is a diagram showing an example of a flowchart showing a processing procedure in a hot gas heating mode in a vehicle air conditioner according to the first embodiment and the second embodiment. FIG. 4 is a diagram showing an example of a flowchart showing a processing procedure in a hot gas heating mode in a vehicle air conditioner according to the first embodiment and the second embodiment. FIG. 5 is a diagram showing an example of a flowchart showing a processing procedure in a hot gas heating mode in a vehicle air conditioner according to the first embodiment and the second embodiment. FIG. 6 is a diagram showing an outline of an exemplary configuration of a vehicle air conditioner according to the second embodiment, and is a diagram showing an example of the state of the vehicle air conditioner when hot gas heating is performed. FIG. 7 is a diagram showing an example of a flowchart showing a processing procedure in a hot gas heating mode in a vehicle air conditioner according to the second embodiment.

[0008] First Embodiment A first embodiment will be described.

[0009] [Configuration of Vehicle Air Conditioner] <Overview of Vehicle Air Conditioner> This embodiment relates to a vehicle air conditioner having a refrigerant circuit and a heat medium circuit. The vehicle air conditioner of this embodiment is installed in an electric vehicle and is configured to improve rapid heating, avoid a decrease in the refrigerant suction density of the compressor, and extend the life of the compressor. The vehicle air conditioner of this embodiment is also configured to improve rapid heating. The vehicle air conditioner of this embodiment is also configured to increase the heating capacity of the vehicle cabin when the heating capacity of the vehicle cabin does not reach a target heating capacity. The vehicle air conditioner of this embodiment is also configured to prevent the occurrence of liquid backflow. The vehicle air conditioner of this embodiment is also configured to suppress heat loss.

[0010] FIG. 1 is an explanatory diagram showing an outline of a configuration example of a vehicle air conditioner 1 according to this embodiment.

[0011] The vehicle air conditioner 1 includes a refrigerant circuit 10 configured to circulate a refrigerant. The refrigerant may be, but is not limited to, a hydrofluoroolefin. The vehicle air conditioner 1 also includes a battery temperature control circuit 40 configured to circulate a heat transfer medium fluid, such as a coolant liquid.

[0012] The automotive air conditioner 1 also includes an HVAC (Heating, Ventilation, and Air Conditioning) unit 100. The automotive air conditioner 1 also includes a control device 200 (see FIG. 2) that controls the operation of various sensors and each part of the automotive air conditioner 1. The operation of the automotive air conditioner 1 is controlled based on the detected values ​​of the various sensors, various requests, etc.

[0013] The refrigerant circuit 10 includes a compressor 11 that compresses gaseous refrigerant to a high temperature and high pressure and then discharges it, a heater core 12 that is housed in a case 110 of the HVAC unit 100 and heats air to be supplied to the vehicle cabin, pressure reduction devices 13a, 13b, 13c, 13d, and 13e such as expansion valves that expand the liquid refrigerant to a low pressure, a low-temperature side heat exchanger 14 that evaporates the low-temperature, low-pressure liquid refrigerant to absorb heat, an accumulator 15, a cooler core 16 that is housed in the case 110 of the HVAC unit 100 and cools the air to be supplied to the vehicle cabin, and a radiator 17 that serves as an exterior heat exchanger. The refrigerant circuit 10 is configured to function as a heat pump that circulates the refrigerant and repeatedly compresses, condenses, expands, and evaporates the refrigerant.

[0014] In the low-temperature side heat exchanger 14, the refrigerant exchanges heat with the heat medium circulating in the battery temperature control circuit 40. In the example shown in the figure, the low-temperature side heat exchanger 14 includes a refrigerant passage 14a through which the refrigerant circulating in the refrigerant circuit 10 passes, and a heat medium passage 14b through which the heat medium circulating in the battery temperature control circuit 40 passes.

[0015] The elements of the refrigerant circuit 10 are connected by refrigerant flow paths 10a, 10b, 10c, 10d, 10e, 10f, 10g, 10h, 10i, 10j, 10k, 10m, 10n, 10p, 10q, 10r, 10s, 10t, 10u, 10v, and 10w.

[0016] The discharge side 11a of the compressor 11 is connected to the inlet side 12a of the heater core 12 via a refrigerant flow path 10a connected thereto, a branch point 18a, and a downstream refrigerant flow path 10b. A flow path opening / closing valve 20a is installed on the path of the refrigerant flow path 10b.

[0017] The discharge side 11a of the compressor 11 is connected to the inlet side 15a of the accumulator 15 via a refrigerant flow path 10a, a branch point 18a, a refrigerant flow path 10c, a branch point 18b, a refrigerant flow path 10d, a junction point 19a, a refrigerant flow path 10e, a junction point 19b, and a downstream refrigerant flow path 10f. A pressure reducing device 13a serving as a first bypass pressure reducing device is installed on the refrigerant flow path 10c. A flow path opening / closing valve 20b is installed on the refrigerant flow path 10f.

[0018] The outlet side 15b of the accumulator 15 is connected to the suction side 11b of the compressor 11 via a refrigerant flow path 10g connected thereto, a junction 19c, and a downstream refrigerant flow path 10h. A check valve 21a is installed on the refrigerant flow path 10g to prevent the refrigerant from flowing back into the accumulator 15.

[0019] The discharge side 11a of the compressor 11 is connected to the suction side 11b of the compressor 11 via a refrigerant flow path 10a, a branch point 18a, a refrigerant flow path 10c, a branch point 18b, a refrigerant flow path 10i, a junction point 19c, and a downstream refrigerant flow path 10h. A pressure reducing device 13b serving as a second bypass pressure reducing device is installed on the refrigerant flow path 10i.

[0020] The outlet side 12b of the heater core 12 is connected to the inlet side 16a of the cooler core 16 via a refrigerant flow path 10j, a branch point 18c, a refrigerant flow path 10k, a junction 19d, a refrigerant flow path 10m, a branch point 18d, and a downstream refrigerant flow path 10n. A flow path opening / closing valve 20c is provided on the path of the refrigerant flow path 10k. A pressure reducing device 13c is provided on the path of the refrigerant flow path 10n.

[0021] An outlet side 16b of the cooler core 16 is connected to an inlet side 15a of the accumulator 15 via a refrigerant flow path 10p, a junction 19e, a refrigerant flow path 10q, a junction 19a, a refrigerant flow path 10e, a junction 19b, and a downstream refrigerant flow path 10f. A check valve 21b is provided on the refrigerant flow path 10q to prevent the refrigerant from flowing back into the cooler core 16.

[0022] The outlet side 12b of the heater core 12 is connected to the inlet of the refrigerant passage 14a of the low-temperature side heat exchanger 14 via the refrigerant flow path 10j, branch point 18c, refrigerant flow path 10k, junction 19d, refrigerant flow path 10m, branch point 18d, and the downstream refrigerant flow path 10r. A pressure reducing device 13d is installed on the path of the refrigerant flow path 10r.

[0023] The outlet of the refrigerant passage 14a of the low-temperature side heat exchanger 14 is connected to the inlet side 15a of the accumulator 15 via a refrigerant passage 10s connected thereto, a junction 19b, and a refrigerant passage 10f downstream thereof. A passage opening / closing valve 20d is installed on the path of the refrigerant passage 10s.

[0024] An outlet side 12b of the heater core 12 is connected to an inlet side 17a of a radiator 17 via a refrigerant flow path 10j connected thereto, a branch point 18c, and a downstream refrigerant flow path 10t. A pressure reducing device 13e is installed on the path of the refrigerant flow path 10t.

[0025] The outlet side 17b of the radiator 17 is connected to the inlet side 15a of the accumulator 15 via the refrigerant flow path 10u, branch point 18e, refrigerant flow path 10v, junction 19e, refrigerant flow path 10q, junction 19a, refrigerant flow path 10e, junction 19b, and the downstream refrigerant flow path 10f. A flow path opening / closing valve 20e is provided on the path of the refrigerant flow path 10v.

[0026] An outlet side 17b of the radiator 17 is connected to an inlet side 16a of the cooler core 16 via a refrigerant flow path 10u, a branch point 18e, a refrigerant flow path 10w, a junction 19d, a refrigerant flow path 10m, a branch point 18d, and a downstream refrigerant flow path 10n. A check valve 21c is provided on the path of the refrigerant flow path 10w to prevent the refrigerant from flowing back into the radiator 17.

[0027] The outlet side 17b of the radiator 17 is connected to the inlet of the refrigerant passage 14a of the low-temperature side heat exchanger 14 via the refrigerant flow path 10u, branch point 18e, refrigerant flow path 10w, junction 19d, refrigerant flow path 10m, branch point 18d, and the downstream refrigerant flow path 10r connected thereto.

[0028] <Battery Temperature Control Circuit> The battery temperature control circuit 40 as an in-vehicle heat-generating device temperature control circuit includes the heat medium passage 14b of the low-temperature side heat exchanger 14 described above and a battery 41 as an in-vehicle heat-generating device. The battery 41 is provided with a battery temperature control unit for controlling the temperature of the battery 41. The battery temperature control circuit 40 can be used to adjust the temperature of the battery 41.

[0029] Note that a configuration similar to that of the battery temperature control circuit 40 can also be applied to other in-vehicle equipment temperature control circuits having an in-vehicle equipment temperature control unit for controlling the temperature of other in-vehicle equipment that similarly requires temperature control, not limited to the battery.

[0030] In the example shown in the figure, the elements of the battery temperature control circuit 40 are connected by heat medium flow paths 40a and 40b. The inlet side 41a of the battery 41 is connected to the outlet of the heat medium path 14b of the low-temperature side heat exchanger 14 by the heat medium flow path 40a. The outlet side 41b of the battery 41 is connected to the inlet of the heat medium path 14b of the low-temperature side heat exchanger 14 by the heat medium flow path 40b.

[0031] On the path of the heat medium flow path 40b, a circulation pump P40 and a heat medium heater 42 are installed in this order from the upstream side. The heat medium can be circulated by the circulation pump P40, and the temperature of the battery 41 can be adjusted.

[0032] <HVAC Unit> The heater core 12 and the cooler core 16 of the refrigerant circuit 10 are housed in a case 110 of the HVAC unit 100. The case 110 forms the outer shell of the HVAC unit 100 and defines an air flow passage 120 therein.

[0033] The HVAC unit 100 also has an intake unit 130. The intake unit 130 closes either an outside air intake port that introduces outside air into the vehicle cabin or an inside air intake port that introduces inside air into the vehicle cabin, thereby switching the air introduced into the case 110 between outside air (outside air intake) and inside air (inside air circulation). The HVAC unit 100 also has a blower 140 installed adjacent to the intake unit 130 so that the air introduced into the case 110 is supplied to the air flow passage 120.

[0034] A cooler core 16 is installed at the upstream side of the air flow passage 120. A heater core passage 121 and a bypass passage 122 are formed in parallel at the downstream side of the air flow passage 120. The heater core 12 is provided in the heater core passage 121. Therefore, when air introduced into the case 110 is guided to the heater core passage 121, the air is ventilated through the cooler core 16 and then through the heater core 12. On the other hand, when air introduced into the case 110 is guided to the bypass passage 122, the air is ventilated through the cooler core 16 and then bypasses the heater core 12. The ratio of air passing through the heater core passage 121 and air passing through the bypass passage 122 is adjusted by an air mix damper 150.

[0035] <Controller> FIG. 2 is an explanatory diagram showing an outline of an example of the configuration of the controller 200 of the vehicle air conditioner 1 according to this embodiment.

[0036] The control device 200 controls the operation of various sensors and various components of the vehicle air conditioner 1. The control device 200 is an air conditioning ECU (Electronic Control Unit) that executes various control modes of the vehicle air conditioner 1. The various control modes executed by the control device 200 include a hot gas heating mode that executes hot gas heating.

[0037] Detection information from various sensors is input to the control device 200. In the hot gas heating mode, detection information from a blower temperature sensor 210, an outside air temperature sensor 220, a refrigerant temperature sensor 230, a refrigerant pressure sensor 240, and a passenger compartment temperature sensor 250 is input to the control device 200. The refrigerant temperature sensor 230 and the refrigerant pressure sensor 240 can detect the temperature and pressure of each part of the refrigerant circuit 10, such as the discharge side 11 a and the suction side 11 b of the compressor 11.

[0038] The control device 200 selects a path in the refrigerant circuit 10 by opening and closing the pressure reducing devices 13a to 13e and the flow path opening and closing valves 20a to 20d based on detection information from various sensors. While selecting the path, the control device 200 also controls the operation of the compressor 11, the blower 140, the air mix damper 150, the circulation pump P40, and the pressure reducing devices 13a to 13e to control the amount of heat released from the refrigerant.

[0039] [Operation of Vehicle Air Conditioner] A specific operation of the vehicle air conditioner 1 according to this embodiment will be described.

[0040] 1 shows the state of the vehicle air conditioner 1 when the outside temperature is extremely low. At this time, the vehicle interior is heated by executing the hot gas heating mode.

[0041] In the hot gas heating mode, the control device 200 fully closes the pressure reducing devices 13c and 13e and opens the flow path opening / closing valves 20a, 20b, 20c, 20d, and 20e.

[0042] As a result, the refrigerant discharged from the compressor 11 flows into refrigerant flow paths 10a and 10b and passes through the heater core 12. The refrigerant that has passed through the heater core 12 flows into refrigerant flow paths 10j, 10k, 10m, and 10r and passes through the refrigerant passage 14a of the low-temperature side heat exchanger 14. The refrigerant that has passed through the refrigerant passage 14a of the low-temperature side heat exchanger 14 flows into refrigerant flow paths 10s and 10f and flows into the accumulator 15. The refrigerant that has flowed into the accumulator 15 flows into refrigerant flow paths 10g and 10h and then flows into the compressor 11. In other words, the refrigerant flow paths 10a, 10b, 10j, 10k, 10m, 10r, 10s, 10f, 10g, and 10h form a circulation path in which the refrigerant that has passed through the compressor 11 passes through the heater core 12.

[0043] The refrigerant discharged from the compressor 11 flows through the refrigerant flow paths 10a, 10c, 10d, 10e, and 10f and then flows into the accumulator 15. The refrigerant that flows into the accumulator 15 flows through the refrigerant flow paths 10g and 10h and then flows into the compressor 11. That is, the refrigerant flow paths 10a, 10c, 10d, 10e, 10f, 10g, and 10h form a bypass path through which the refrigerant that has passed through the compressor 11 detours without passing through the heater core 12. This bypass path also forms a first path through which the refrigerant that has passed through the compressor 11 flows upstream of the accumulator 15.

[0044] The refrigerant discharged from the compressor 11 flows through the refrigerant flow paths 10a, 10c, 10i, and 10h and then enters the compressor 11. That is, the refrigerant flow paths 10a, 10c, 10i, and 10h form a bypass path through which the refrigerant that has passed through the compressor 11 detours without passing through the heater core 12. The bypass path also forms a second path through which the refrigerant that has passed through the compressor 11 flows downstream of the accumulator 15.

[0045] The control device 200 adjusts the throttle amount of the pressure reducing device 13a to cause a portion of the refrigerant discharged from the compressor 11 to flow through the heater core 12 and the remaining refrigerant to flow through the bypass path. As a result, the vehicle cabin is heated by the heat of the refrigerant dissipated by the heater core 12. Furthermore, the refrigerant flowing through the bypass path has a higher temperature when it returns to the suction side 11b of the compressor 11 than the refrigerant that passes through the heater core 12. As a result, in the hot gas heating mode, the temperature of the refrigerant discharged from the compressor 11 can be increased to maintain heating capacity.

[0046] The control device 200 can also flow refrigerant through the first and second paths by opening the flow path on-off valve 20b and adjusting the throttle amount of the pressure reducing device 13b. As a result, the refrigerant discharged from the compressor 11 is warmed in the accumulator 15 and directly returned to the suction side 11b of the compressor 11, improving the condition of the refrigerant flowing into the suction side 11b of the compressor 11 and improving the heating speed. By flowing the refrigerant circulating through the first path into the accumulator 15, the refrigerant circulation rate can be increased, preventing a decrease in the suction density of the refrigerant at the suction side 11b of the compressor 11. By flowing the refrigerant circulating through the second path downstream of the accumulator 15, superheated refrigerant can be flowed. This ensures evaporation of the refrigerant flowing into the suction side 11b of the compressor 11, preventing liquid backflow into the compressor 11, and extending the life of the compressor 11.

[0047] In this embodiment, it is preferable to configure the second path to branch off from the first path and provide a pressure reducing device 13a at least in the first path. In addition, by providing a pressure reducing device 13b to adjust the flow rate of the refrigerant, it is possible to increase the circulation amount of the refrigerant while preventing the occurrence of liquid backflow.

[0048] In addition, as in this embodiment, it is preferable to provide a pressure reducing device 13a upstream of the branch point 18b where the first path branches into the second path, which makes it easier to adjust the amount of refrigerant bypassing the heater core 12, thereby facilitating control of the hot gas heating mode while maintaining heating capacity.

[0049] In addition, in the present embodiment, an example has been described in which the pressure reducing device 13a is provided upstream of the branch point 18b where the first path branches into the second path, but the pressure reducing device 13a may be provided downstream of the branch point 18b where the first path branches into the second path, and the pressure reducing device 13b may be provided in the second path. This makes it easier to adjust the flow rate of the refrigerant flowing into the accumulator 15 and the flow rate of the refrigerant bypassing the accumulator 15, and therefore makes it easier to control the density of the refrigerant flowing into the suction side 11b of the compressor 11.

[0050] [Various Controls in Hot Gas Heating Mode] Next, the control by the control device 200 for adjusting the flow rate of refrigerant in the bypass path in the vehicle air conditioner 1 configured as shown in Fig. 1 will be described with reference to Fig. 3 to Fig. 5. Note that the vehicle air conditioner 1 may be configured to perform one of the controls shown in Fig. 3 to Fig. 5, or may be configured to perform a plurality of controls.

[0051] FIG. 3 is a flowchart showing an example of a specific control process procedure of the control device 200 regarding adjustment of the flow rates of refrigerant in the first and second paths when starting up the hot gas heating mode.

[0052] 3, when the outside air temperature is extremely low, the control device 200 activates the hot gas heating mode (S1). At this time, the control device 200 fully closes the pressure reducing devices 13c and 13e and opens the flow path opening / closing valves 20a, 20b, 20c, 20d, and 20e.

[0053] The control device 200 then determines whether the suction pressure of the compressor 11 is equal to or greater than a threshold value (S2). Whether the suction pressure is equal to or greater than the threshold value is determined by determining, for example, whether the pressure is positive, in other words, whether the pressure is not negative.

[0054] If the suction pressure of the compressor 11 is not equal to or greater than the threshold (S2: No), the control device 200 closes the flow path on-off valve 20b. As a result, the second path is set as a bypass path that bypasses the heater core 12 (S3). As a result, all of the refrigerant flowing through the bypass path flows through the second path. Therefore, the flow rate of the refrigerant through the second path is greater than that of the first path. This reduces heat dissipation from the refrigerant in the accumulator 15, thereby increasing the temperature of the refrigerant drawn into the compressor 11. This allows the refrigerant condition to be improved quickly, thereby improving rapid heating. Furthermore, by directing all of the refrigerant flowing through the bypass path through the second path, heat dissipation from the refrigerant that occurs when the refrigerant flows into the accumulator 15 is eliminated, thereby reducing heat loss from the refrigerant.

[0055] When the suction pressure of the compressor 11 is equal to or higher than the threshold value (S2: Yes), the control device 200 opens the flow path on-off valve 20b. As a result, the first path and the second path are set as bypass paths that bypass the heater core 12 (S4). As a result, the refrigerant flowing through the bypass path passes through the accumulator 15, thereby increasing the density of the refrigerant drawn into the compressor 11.

[0056] In this embodiment, an example has been described in which the refrigerant flows only through the second path when the suction pressure of the compressor 11 is not equal to or higher than the threshold value. However, even when the suction pressure of the compressor 11 is not equal to or higher than the threshold value, the flow path opening / closing valve 20b may be opened to allow the refrigerant to flow through the first path and the second path, and the flow rate may be adjusted by the pressure reducing device 13b so that the refrigerant flow rate through the second path is greater than that of the first path.

[0057] FIG. 4 is a flowchart showing an example of a specific control process procedure performed by the control device 200 regarding adjustment of the flow rate of the refrigerant in the second path when the hot gas heating mode is executed.

[0058] 4, the control device 200 calculates the target heating capacity for the vehicle cabin in the hot gas heating mode (S1). The target heating capacity is calculated as follows: Target heating capacity = (target heater core outlet temperature - heater core inlet air temperature) x air volume. The target heater core outlet temperature is calculated based on the difference between the set temperature for the vehicle cabin and the actual temperature for the vehicle cabin when the target heating capacity is calculated.

[0059] Next, the control device 200 determines whether the heating capacity for the vehicle interior has reached the target heating capacity (S2). The heating capacity for the vehicle interior is calculated as follows: Heating capacity = (actual heater core outlet temperature at the time of calculating the heating capacity - heater core inlet air temperature) x air volume

[0060] If the heating capacity of the vehicle cabin has reached the target heating capacity (S2: Yes), the flow rate of the refrigerant flowing through the second path is maintained by adjusting the throttle amount of the pressure reducing device 13b (S3). As a result, the ratio of the flow rate of the refrigerant flowing through the first path to the flow rate of the refrigerant flowing through the second path is maintained. This makes it possible to achieve the target heating capacity by appropriately superheating the refrigerant flowing through the compressor 11, thereby improving passenger comfort.

[0061] On the other hand, if the heating capacity of the vehicle cabin has not reached the target heating capacity (S2: No), the flow rate of the refrigerant flowing through the second path is increased by adjusting the throttle amount of the pressure reducing device 13b (S4). This allows the refrigerant flowing through the second path to merge with the first path to superheat the refrigerant flowing from the accumulator 15 to the compressor 11 via the first path, thereby increasing the heating capacity of the vehicle cabin when the heating capacity has not reached the target heating capacity.

[0062] The control device 200 then determines whether the heating capacity for the vehicle cabin has decreased (S5). If the heating capacity for the vehicle cabin has decreased (S5: Yes), the control device 200 adjusts the throttle amount of the pressure reducing device 13b to reduce the flow rate of the refrigerant flowing through the second path (S6). As a result, the flow rate of the refrigerant flowing through the second path is increased too much, which causes the flow rate of the refrigerant flowing through the bypass path to decrease, resulting in a decrease in the heating capacity for the vehicle cabin. By reducing the flow rate of the refrigerant flowing through the second path, the flow rate of the refrigerant passing through the heater core 12 can be increased. This improves the heating capacity and prevents a decrease in passenger comfort.

[0063] If the heating capacity for the passenger compartment has not decreased (S5: No), the process ends.

[0064] 4 preferably includes a step of determining whether the heating capacity of the vehicle cabin exceeds the target heating capacity. When the control device 200 determines that the heating capacity of the vehicle cabin exceeds the target heating capacity, the control device 200 preferably adjusts the throttle amount of the pressure reducing device 13b to reduce the flow rate of the refrigerant flowing through the second path. This allows the heating capacity of the vehicle cabin to be adjusted to the target heating capacity, thereby improving passenger comfort.

[0065] FIG. 5 is a flowchart showing an example of a specific control process procedure performed by the control device 200 regarding adjustment of the flow rate of the refrigerant in the second path when the hot gas heating mode is executed.

[0066] 5, in the hot gas heating mode, the control device 200 estimates the saturated vapor temperature (Tvap) based on the pressure of the refrigerant on the suction side 11b of the compressor 11 (S1). Specifically, the control device 200 has data related to a Ph diagram, and estimates the saturated vapor temperature (Tvap) based on the pressure of the refrigerant on the suction side 11b of the compressor 11 and the Ph diagram.

[0067] Next, the control device 200 determines whether the refrigerant temperature (Ts) on the suction side 11b of the compressor 11 is lower than the saturated vapor temperature (Tvap) (S2). If the refrigerant temperature (Ts) is lower than the saturated vapor temperature (Tvap) (S2: Yes), the control device 200 adjusts the throttle amount of the pressure reducing device 13b to increase the flow rate of the refrigerant flowing through the second path (S3). If the refrigerant temperature (Ts) is not lower than the saturated vapor temperature (Tvap) (S2: No), the process ends.

[0068] In this way, by increasing the flow rate of the refrigerant in the second path through which high-temperature refrigerant flows without passing through the accumulator 15, it is possible to prevent the temperature (Ts) of the refrigerant on the suction side 11b of the compressor 11 from becoming lower than the saturated vapor temperature (Tvap) of the refrigerant under the same pressure condition. This prevents the compressor 11 from drawing in a gas-liquid mixed refrigerant, which would otherwise cause liquid backflow in the compressor 11.

[0069] Second Embodiment A second embodiment will be described.

[0070] FIG. 6 is an explanatory diagram showing an outline of a configuration example of a vehicle air conditioner 1 according to the second embodiment.

[0071] The vehicle air conditioner 1 according to the second embodiment and the vehicle air conditioner 1 according to the first embodiment have different configurations of the refrigerant circuit 10, but detailed descriptions of common configurations will be omitted. Also, the vehicle air conditioner 1 according to the second embodiment and the vehicle air conditioner 1 according to the first embodiment have the same configurations of the battery temperature control circuit 40 and the HVAC unit 100, so descriptions of these will be omitted.

[0072] In the refrigerant circuit 10 according to the second embodiment, the discharge side 11a of the compressor 11 is connected to the inlet side 15a of the accumulator 15 via a refrigerant flow path 10a, a branch point 18a, a refrigerant flow path 10c, a proportional control three-way valve V30, a refrigerant flow path 10d, a junction 19a, a refrigerant flow path 10e, a junction 19b, and a refrigerant flow path 10f downstream thereof. A flow path opening / closing valve 20b is provided on the path of the refrigerant flow path 10f.

[0073] In addition, the discharge side 11a of the compressor 11 is connected to the suction side 11b of the compressor 11 via the refrigerant flow path 10a, branch point 18a, refrigerant flow path 10c, refrigerant flow path 10i, junction point 19c, and the downstream refrigerant flow path 10h connected thereto.

[0074] As described above, the refrigerant circuit 10 according to the second embodiment differs from the refrigerant circuit 10 according to the first embodiment in that it does not include the branch point 18b and the pressure reducing device 13b that are included in the refrigerant circuit 10 according to the first embodiment, but does include the proportional control three-way valve V30. In addition, the refrigerant circuit 10 according to the second embodiment has the same other configuration as the refrigerant circuit 10 according to the first embodiment.

[0075] <Controller> The vehicle air conditioner 1 according to the second embodiment is controlled by a controller 200 shown in FIG.

[0076] [Operation of Vehicle Air Conditioner] Specific operations of the vehicle air conditioner 1 according to this embodiment will be described with reference to Fig. 6. Note that only the parts of the operation that differ from the vehicle air conditioner 1 according to the first embodiment will be described, and detailed descriptions of the parts of the operation that are common to the vehicle air conditioner 1 according to the first embodiment will be omitted.

[0077] <Hot Gas Heating Mode> Fig. 6 shows the state of the vehicle air conditioner 1 when the outside air temperature is extremely low. At this time, the vehicle interior is heated by executing hot gas heating.

[0078] Unlike the vehicle air conditioner 1 according to the first embodiment, in the hot gas heating mode of the vehicle air conditioner 1 according to the second embodiment, the control device 200 controls the flow rate of the refrigerant using the proportional control three-way valve V30 instead of the pressure reducing device 13b, thereby allowing the refrigerant to flow through the first and second paths. As a result, the refrigerant discharged from the compressor 11 is returned directly to the suction side 11b of the compressor 11 while the refrigerant in the accumulator 15 is heated, improving the condition of the refrigerant flowing into the suction side 11b of the compressor 11 and enhancing the heating speed. Furthermore, by allowing the refrigerant circulating through the first path to flow into the accumulator 15, the amount of refrigerant circulating can be increased, preventing a decrease in the suction density of the refrigerant on the suction side 11b of the compressor 11. Furthermore, by flowing the refrigerant circulating through the second path downstream of the accumulator 15, it becomes possible to flow superheated refrigerant, which ensures that the refrigerant flowing into the suction side 11b of the compressor 11 is evaporated, preventing liquid backflow into the compressor 11 and extending the life of the compressor 11.

[0079] In this embodiment, the second path is branched off from the first path, but it is preferable to provide a pressure reducing device 13a at least in the first path. In addition, by providing a proportional control three-way valve V30 and adjusting the flow rate of the refrigerant, it is possible to increase the amount of refrigerant circulating while preventing liquid backflow.

[0080] It is also preferable to provide a pressure reducing device 13a upstream of the proportional control three-way valve V30, which branches from the first path to the second path. This facilitates adjustment of the amount of refrigerant bypassing the heater core 12, making it easier to control the hot gas heating mode while maintaining heating capacity.

[0081] In addition, in the present embodiment, an example has been described in which the pressure reducing device 13a is provided upstream of the proportional control three-way valve V30 that branches from the first path to the second path, but the pressure reducing device 13a may be provided downstream of the proportional control three-way valve V30 that branches from the first path to the second path, and the pressure reducing device 13b may be provided in the second path. This makes it easy to adjust the flow rate of the refrigerant flowing into the accumulator 15 and the flow rate of the refrigerant bypassing the accumulator 15, and therefore makes it easy to control the density of the refrigerant flowing into the suction side 11b of the compressor 11.

[0082] [Various Controls in Hot Gas Heating Mode] Next, in the vehicle air conditioner 1 configured as shown in Fig. 6, the control device 200 can perform the same control as shown in Fig. 3 to Fig. 5 regarding the adjustment of the flow rate of refrigerant in the first and second paths. Note that the vehicle air conditioner 1 according to the second embodiment may also be configured to perform one of the controls shown in Fig. 3 to Fig. 5, or may be configured to perform a plurality of controls.

[0083] Furthermore, in the vehicle air conditioner 1 according to the first embodiment, the flow rate of the refrigerant in the first path and the second path is adjusted by adjusting the throttling amount by the pressure reducing device 13b in the control shown in Figures 3 to 5. However, in the vehicle air conditioner 1 according to the second embodiment, the flow rate of the refrigerant in the first path and the second path is adjusted by the proportional control three-way valve V30 in the control shown in Figures 3 to 5, unlike the vehicle air conditioner 1 according to the first embodiment.

[0084] Furthermore, the vehicle air conditioner 1 according to the second embodiment can execute the control shown in Fig. 7 in the hot gas heating mode. Fig. 7 is a flowchart showing an example of a specific control process procedure of the control device 200 that can switch to the accumulator bypass path when the hot gas heating mode is executed.

[0085] 7, the control device 200 calculates the refrigerant circulation amount (S1). In calculating the refrigerant circulation amount, the refrigerant density is first calculated based on the suction pressure and suction temperature of the compressor 11. Then, the refrigerant circulation amount is calculated based on the calculated refrigerant density and the rotation speed of the compressor 11.

[0086] Next, the control device 200 determines whether the refrigerant circulation rate is appropriate (S2). Whether the refrigerant circulation rate is appropriate is determined based on whether the heating capacity is excessive or insufficient due to the refrigerant circulation rate.

[0087] If the refrigerant circulation rate is appropriate (S2: Yes), the flow path on-off valve 20b is closed (S3). As a result, the refrigerant discharged from the compressor 11 flows into the refrigerant flow paths 10a and 10b and passes through the heater core 12. The refrigerant that has passed through the heater core 12 flows into the refrigerant flow paths 10j, 10k, 10m, and 10r and passes through the refrigerant passage 14a of the low-temperature side heat exchanger 14. The refrigerant that has passed through the refrigerant passage 14a of the low-temperature side heat exchanger 14 flows into the refrigerant flow paths 10s, 10e, 10d, 10i, and 10h, bypassing the accumulator 15, and then flows into the compressor 11. As a result, the refrigerant that has flowed into the heater core 12 bypasses the accumulator 15 through the refrigerant flow paths 10e and 10d of the first path and the refrigerant flow paths 10c, 10i, and 10h of the second path, and then flows through the accumulator bypass path that flows into the suction side 11b of the compressor 11. Furthermore, the refrigerant discharged from the compressor 11 flows into the refrigerant flow paths 10 a , 10 c , 10 i , and 10 h and then flows into the compressor 11 .

[0088] In this way, when the refrigerant circulation amount is appropriate, by switching to the accumulator bypass path, heat is not taken from the refrigerant in the accumulator 15, and heat loss of the refrigerant can be suppressed.

[0089] If the refrigerant circulation rate is inappropriate (S2: No), the flow path on-off valve 20b is opened (S4). As a result, the refrigerant discharged from the compressor 11 flows into the refrigerant flow paths 10a and 10b and passes through the heater core 12. The refrigerant that passes through the heater core 12 flows into the refrigerant flow paths 10j, 10k, 10m, and 10r and passes through the refrigerant passage 14a of the low-temperature side heat exchanger 14. The refrigerant that passes through the refrigerant passage 14a of the low-temperature side heat exchanger 14 flows into the refrigerant flow paths 10s and 10f and flows into the accumulator 15. The refrigerant that flows into the accumulator 15 flows into the refrigerant flow paths 10g and 10h and then into the compressor 11. Furthermore, the refrigerant discharged from the compressor 11 flows into the refrigerant flow paths 10a, 10c, 10d, 10e, and 10f and then flows into the accumulator 15. The refrigerant that flows into the accumulator 15 flows into the refrigerant flow paths 10g and 10h and then flows into the compressor 11. The refrigerant that is discharged from the compressor 11 flows into the refrigerant flow paths 10a, 10c, 10i, and 10h and then flows into the compressor 11.

[0090] In this way, when the refrigerant circulation amount is not appropriate, the refrigerant circulation amount can be ensured by passing through the accumulator 15 .

[0091] The vehicle air conditioner 1 of this embodiment can achieve the following effects.

[0092] (a1) A refrigerant circuit 10 is configured to circulate through a compressor 11, a heater core 12 that heats the air supplied to the vehicle interior, pressure reducing devices 13a to 13e, a low-temperature side heat exchanger 14 that causes a refrigerant to absorb heat from a heat medium that has absorbed heat from a battery 41 as an in-vehicle heat generating device, and an accumulator 15, and includes a bypass path through which the refrigerant that has passed through the compressor 11 bypasses the heater core 12 and flows into the intake side 11b of the compressor 11, and a part of the refrigerant that has passed through the compressor 11 is returned to the heater core 12. and a control device (200) capable of controlling the vehicular air conditioning system (1) to a hot gas heating mode in which the refrigerant flows through the bypass path and the remaining refrigerant flows through the bypass path. The bypass path includes refrigerant flow paths (10a, 10c, 10d, 10e, 10f, 10g, and 10h) as a first path through which the refrigerant that has passed through the compressor (11) flows upstream of the accumulator (15), and refrigerant flow paths (10a, 10c, 10i, and 10h) as a second path through which the refrigerant that has passed through the compressor (11) flows downstream of the accumulator (15). Thus, by warming the refrigerant in the accumulator (15) and directly returning the refrigerant discharged from the compressor (11) to the suction side (11b) of the compressor (11), the condition of the refrigerant flowing into the suction side (11b) of the compressor (11) can be improved, thereby improving the heating speed. Furthermore, by flowing the refrigerant circulating through the first path into the accumulator (15), the amount of refrigerant circulating can be increased, preventing a decrease in the suction density of the refrigerant at the suction side (11b) of the compressor (11). Furthermore, by flowing the refrigerant circulating through the second path downstream of the accumulator 15, it becomes possible to flow superheated refrigerant, which ensures that the refrigerant flowing into the suction side 11b of the compressor 11 is evaporated, preventing liquid backflow into the compressor 11 and extending the life of the compressor 11.

[0093] (a2) The second path is a path that branches off from the first path and joins downstream of the accumulator 15, and at least the first path is provided with the pressure reducing device 13a as a first bypass pressure reducing device. Therefore, by providing the pressure reducing devices 13a and 13b in the first path and the second path, respectively, and adjusting the flow rate of the refrigerant, it is possible to increase the circulation amount of the refrigerant while preventing liquid backflow.

[0094] (a3) The pressure reducing device 13a serving as the first bypass pressure reducing device is provided upstream of the branch point 18b where the first path branches into the second path. This facilitates adjustment of the amount of refrigerant bypassing the heater core 12, making it easier to control the hot gas heating mode while maintaining heating capacity.

[0095] (a4) The pressure reducing device 13a serving as the first bypass pressure reducing device is provided downstream of the branch point 18b where the first path branches into the second path, and the pressure reducing device 13b serving as the second bypass pressure reducing device is provided in the second path. This facilitates adjustment of the flow rate of the refrigerant flowing into the accumulator 15 and the flow rate of the refrigerant bypassing the accumulator 15, thereby facilitating control of the density of the refrigerant flowing into the suction side 11b of the compressor 11.

[0096] (b1) A refrigerant circuit 10 is configured to circulate through a compressor 11, a heater core 12 that heats the air supplied to the vehicle interior, pressure reducing devices 13a to 13e, a low-temperature side heat exchanger 14 that causes the refrigerant to absorb heat from the heat medium absorbed from the battery 41 as an on-vehicle heat generating device, and an accumulator 15, and includes a bypass path through which the refrigerant that has passed through the compressor 11 bypasses the heater core 12 and flows into the suction side 11b of the compressor 11, and a hot gas heating mode in which a portion of the refrigerant that has passed through the compressor 11 flows into the heater core 12 and the remaining refrigerant flows into the bypass path. The bypass path includes refrigerant flow paths (10a, 10c, 10d, 10e, 10f, 10g, and 10h) as a first path through which refrigerant that has passed through the compressor (11) flows upstream of the accumulator (15), and refrigerant flow paths (10a, 10c, 10i, and 10h) as a second path through which refrigerant that has passed through the compressor (11) flows downstream of the accumulator (15). When the hot gas heating mode is activated, the control device (200) increases the flow rate of refrigerant through the second path (10a, 10c, 10i, and 10h) compared to the flow rate of refrigerant through the first path. Therefore, when the suction pressure of the compressor (11) is not equal to or higher than a threshold, the control device (200) increases the flow rate of refrigerant through the second path (10a, 10c, 10d, 10e, 10f, 10g, and 10h) compared to the flow rate of refrigerant through the first path (10a, 10c, 10i, and 10h). This suppresses heat radiation from the accumulator (15), thereby increasing the temperature of the refrigerant drawn into the compressor (11). This allows the state of the refrigerant to be improved quickly, thereby improving the quick heating performance.

[0097] (b2) When the hot gas heating mode is activated, the control device 200 directs all of the refrigerant flowing through the bypass path to the second path. Therefore, when the suction pressure of the compressor 11 is not equal to or higher than the threshold, all of the refrigerant flowing through the bypass path is directed to the second path. This prevents the refrigerant from releasing heat when it flows into the accumulator 15, thereby reducing heat loss of the refrigerant.

[0098] (c1) A refrigerant is configured to circulate through a compressor 11, a heater core 12 that heats the air supplied to the vehicle interior, pressure reducing devices 13a to 13e, a low-temperature side heat exchanger 14 that causes the refrigerant to absorb heat from the heat medium absorbed from the battery 41 as an on-vehicle heat generating device, and an accumulator 15, and the refrigerant circuit 10 includes a bypass path where the refrigerant that has passed through the compressor 11 bypasses the heater core 12 and flows into the suction side 11b of the compressor 11, and the refrigerant circuit 10 can be controlled to a hot gas heating mode where a portion of the refrigerant that has passed through the compressor 11 flows into the heater core 12 and the remaining refrigerant flows into the bypass path. and a control device 200. The bypass path includes refrigerant flow paths 10a, 10c, 10d, 10e, 10f, 10g, and 10h as a first path through which refrigerant that has passed through the compressor 11 flows upstream of the accumulator 15, and refrigerant flow paths 10a, 10c, 10i, and 10h as a second path through which refrigerant that has passed through the compressor 11 flows downstream of the accumulator 15. The control device 200 calculates a target heating capacity that is a target value for heating capacity in the vehicle cabin, and controls the flow rate of refrigerant flowing through the second path based on the calculated target heating capacity. Thus, the refrigerant that merges from the second path into the first path can superheat the refrigerant that flows from the accumulator 15 to the compressor 11 via the first path, and the heating capacity in the vehicle cabin can be increased when the heating capacity in the vehicle cabin does not reach the target heating capacity.

[0099] (c2) When the heating capacity of the vehicle interior does not reach the target heating capacity, the control device 200 increases the flow rate of the refrigerant flowing through the second path. This makes it possible to superheat the refrigerant flowing from the accumulator 15 to the compressor 11, thereby increasing the heating capacity of the vehicle interior when the heating capacity of the vehicle interior does not reach the target heating capacity.

[0100] (c3) When the heating capacity of the vehicle interior reaches the target heating capacity, the control device 200 maintains the flow rate of the refrigerant flowing through the second path. This allows the target heating capacity to be achieved by appropriately superheating the refrigerant flowing through the compressor 11, thereby improving passenger comfort.

[0101] (c4) When the flow rate of refrigerant flowing through the second path is increased and the heating capacity of the vehicle cabin decreases, the control device 200 reduces the flow rate of refrigerant flowing through the second path. Therefore, in response to a decrease in the heating capacity of the vehicle cabin caused by a decrease in the flow rate of refrigerant passing through the heater core 12 due to an excessive increase in the flow rate of refrigerant flowing through the bypass path caused by an increase in the flow rate of refrigerant flowing through the second path, the control device 200 can increase the flow rate of refrigerant passing through the heater core 12. This improves the heating capacity and prevents a decrease in passenger comfort.

[0102] (c5) When the heating capacity of the vehicle cabin exceeds the target heating capacity, the control device 200 reduces the flow rate of the refrigerant flowing through the second path. This makes it possible to adjust the heating capacity of the vehicle cabin to the target heating capacity, thereby improving passenger comfort.

[0103] (d1) A vehicular air conditioning system 1 is provided with a refrigerant circuit 10 including a compressor 11, a heater core 12 for heating air supplied to a vehicle interior, pressure reducing devices 13a to 13e, a low-temperature side heat exchanger 14 for absorbing heat from a heat medium absorbed from a battery 41 as an in-vehicle heat generating device into a refrigerant, and an accumulator 15, the refrigerant circuit 10 including a bypass path through which the refrigerant that has passed through the compressor 11 bypasses the heater core 12 and flows into the suction side 11b of the compressor 11, and a control device 200 that can control a hot gas heating mode in which a portion of the refrigerant that has passed through the compressor 11 flows into the heater core 12 and the remaining refrigerant flows into the bypass path, the bypass being configured to allow a refrigerant to circulate through the refrigerant circuit 10. The refrigerant flow path includes refrigerant flow paths 10a, 10c, 10d, 10e, 10f, 10g, and 10h as a first path through which the refrigerant that has passed through the compressor 11 flows to the upstream side of the accumulator 15, and refrigerant flow paths 10a, 10c, 10i, and 10h as a second path through which the refrigerant that has passed through the compressor 11 flows to the downstream side of the accumulator 15. The control device 200 estimates the saturated vapor temperature (Tvap) of the refrigerant on the suction side 11b of the compressor 11 based on the pressure of the refrigerant on the suction side 11b of the compressor 11, and controls the flow rate of the refrigerant flowing through the second path based on the estimated saturated vapor temperature (Tvap) and the temperature (Ts) of the refrigerant on the suction side 11b of the compressor 11. Therefore, by controlling the flow rate of the refrigerant in the second path through which high-temperature refrigerant flows without passing through the accumulator 15, it is possible to prevent the temperature (Ts) of the refrigerant on the suction side 11b of the compressor 11 from becoming lower than the saturated vapor temperature (Tvap) of the refrigerant under the same pressure condition. This prevents the compressor 11 from drawing in a gas-liquid mixed refrigerant, which would otherwise cause liquid backflow in the compressor 11.

[0104] (d2) The control device 200 increases the flow rate of refrigerant flowing through the second path when the temperature of the refrigerant on the suction side 11b of the compressor 11 is lower than the estimated saturated vapor temperature (Tvap). Therefore, by increasing the flow rate of refrigerant through the second path, through which high-temperature refrigerant flows without passing through the accumulator 15, it is possible to prevent the temperature (Ts) of the refrigerant on the suction side 11b of the compressor 11 from falling below the saturated vapor temperature (Tvap) of the refrigerant under the same pressure condition. This prevents the compressor 11 from drawing in a gas-liquid mixed refrigerant, which would otherwise cause liquid backflow in the compressor 11.

[0105] (e1) A vehicular air conditioning device 1 including a refrigerant circuit 10 configured to circulate through a compressor 11, a heater core 12 that heats air supplied to a vehicle interior, pressure reducing devices 13a to 13e, a low-temperature side heat exchanger 14 that causes a refrigerant to absorb heat from a heat medium absorbed from a battery 41 as an on-vehicle heat generating device, and an accumulator 15, the refrigerant circuit 10 including a bypass path through which the refrigerant that has passed through the compressor 11 bypasses the heater core 12 and flows into the suction side 11b of the compressor 11, and a control device 200 that can control the hot gas heating mode so that a portion of the refrigerant that has passed through the compressor 11 flows into the heater core 12 and the remaining refrigerant flows into the bypass path. The bypass path includes refrigerant flow paths 10a, 10c, 10d, 10e, 10f, 10g, and 10h as a first path through which the refrigerant that has passed through the compressor 11 flows upstream of the accumulator 15, and refrigerant flow paths 10a, 10c, 10i, and 10h as a second path through which the refrigerant that has passed through the compressor 11 flows downstream of the accumulator 15. In the hot gas heating mode, the control device 200 can switch the refrigerant that has flowed to the heater core 12 to the accumulator bypass path through the first and second paths to bypass the accumulator 15 and then flow into the suction side 11b of the compressor 11. Therefore, heat is not removed from the refrigerant by the accumulator 15, thereby suppressing heat loss of the refrigerant.

[0106] The present invention has been described above by showing preferred embodiments, but it goes without saying that the present invention is not limited to the above-described embodiments, and various modifications can be made within the scope of the present invention.

[0107] 1: Vehicle air conditioning system 10: Refrigerant circuit, 11: Compressor, 12: Heater core, 13a, 13b, 13c, 13d, 13e: Pressure reducing device, 14: Low temperature side heat exchanger, 15: Accumulator, 16: Cooler core, 17: Radiator 40: Battery temperature control circuit, 41: Battery, P40: Circulation pump 100: HVAC unit, 110: Case, 120: Air flow passage, 121: Heater core passage, 122: Bypass passage, 150: Air mix damper

Claims

1. A vehicular air conditioning system comprising: a refrigerant circuit configured to circulate through a compressor, a heater core which heats air supplied to the vehicle cabin, a pressure reducing device, a low-temperature side heat exchanger which causes a refrigerant to absorb heat from a heat medium absorbed from an on-board heat generating device, and an accumulator, the refrigerant including a bypass path which causes the refrigerant that has passed through the compressor to bypass the heater core and flow into the suction side of the compressor; and a control device capable of controlling a hot gas heating mode in which a portion of the refrigerant that has passed through the compressor flows into the heater core and the remaining refrigerant flows into the bypass path, wherein the bypass path comprises: a first path which causes the refrigerant that has passed through the compressor to flow upstream of the accumulator, and a second path which causes the refrigerant that has passed through the compressor to flow downstream of the accumulator.

2. The vehicle air conditioning system according to claim 1, characterized in that the second path branches off from the first path and joins the downstream side of the accumulator, and a first bypass pressure reducing device is provided on at least the first path.

3. The vehicle air conditioner according to claim 2, wherein the first bypass pressure reducing device is provided upstream of a branch point where the first path branches into the second path.

4. The vehicle air conditioning system according to claim 2, characterized in that the first bypass pressure reducing device is provided downstream of a branch point where the first path branches into the second path, and a second bypass pressure reducing device is provided in the second path.

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