Vehicular air conditioning device

Abstract

[Problem] To provide a vehicular air conditioning device that has good rapid-heating performance. [Solution] A vehicular air conditioning device 1 is provided with a refrigerant circuit 10 that includes: a compressor 11; a heater core 12 that is configured to heat air supplied to a vehicle interior; a decompression device 13; and a low-temperature-side heat exchanger 14 that is configured to exchange heat between a heat transfer medium that exchanges heat with an on-board heat generating apparatus and a refrigerant. A control device 200 lets a portion of the refrigerant that has passed through the compressor 11 flow to the heater core 12 and, in a hot gas heating mode in which the remaining refrigerant is made to flow into a bypass path, if the temperature of the heat transfer medium flowing through the low-temperature-side heat exchanger 14 does not meet a prescribed condition, restricts inflow of the refrigerant into the low-temperature-side heat exchanger 14.

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 has a quick heating property.

[0005] According to one aspect of the present invention, a vehicle air conditioning system includes a compressor, a heater core configured to heat air to be supplied into a vehicle cabin, a pressure reducing device, and a low-temperature side heat exchanger configured to exchange heat between a refrigerant and a heat medium that exchanges heat with an on-board heat-generating device, and the vehicle air conditioning system includes a refrigerant circuit having a path configured to circulate the refrigerant between the compressor, the heater core, the pressure reducing device, and the low-temperature side heat exchanger, and a bypass path through which the refrigerant that has passed through the compressor bypasses the heater core and flows into the suction side of the compressor, a heat medium circuit configured to circulate the heat medium between the on-board heat-generating device and the low-temperature side heat exchanger, and a control device configured to switch and control the refrigerant circuit, and capable of control in 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, and in the hot gas heating mode, the control device restricts the inflow of the refrigerant into the low-temperature side heat exchanger when the temperature of the heat medium flowing through the low-temperature side heat exchanger does not satisfy a predetermined condition.

[0006] According to the present invention, a vehicle air conditioner with good quick heating properties can be provided.

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

[0008] [Configuration of Vehicle Air Conditioner] <Outline 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 mounted on an electric vehicle and is configured to improve quick heating.

[0009] 1 is an explanatory diagram showing an outline of an example configuration of a vehicle air conditioner 1 according to this embodiment. 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 fluid heat transfer medium, such as a coolant.

[0010] The automotive air conditioner 1 also includes an HVAC (Heating, Ventilation, and Air Conditioning) unit 100, which is an air conditioning unit. 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.

[0011] The refrigerant circuit 10 includes a compressor 11 that compresses gaseous refrigerant to a high temperature and high pressure before discharging it, a heater core 12 that is housed in a case 110 of the HVAC unit 100 and heats the air to be supplied to the vehicle cabin, pressure reduction devices 13a, 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.

[0012] 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.

[0013] The elements of the refrigerant circuit 10 are connected by refrigerant flow paths 10a, 10b, 10c, 10d, 10e, 10f, 10g, 10j, 10k, 10m, 10n, 10p, 10q, 10r, 10s, 10t, 10u, 10v, and 10w.

[0014] A discharge side 11a of the compressor 11 is connected to an inlet side 12a of a heater core 12 via a refrigerant flow path 10a connected thereto, a branch point 18a, and a refrigerant flow path 10b downstream of the branch point 18a.

[0015] The discharge side 11a of the compressor 11 is connected to the inlet side 15a of the accumulator 15 via the refrigerant flow path 10a, branch point 18a, refrigerant flow path 10c, refrigerant flow path 10d, junction 19a, refrigerant flow path 10e, junction 19b, and the downstream refrigerant flow path 10f. A pressure reducing device 13a serving as a bypass pressure reducing device is installed on the refrigerant flow path 10c.

[0016] An outlet side 15b of the accumulator 15 is connected to a suction side 11b of the compressor 11 via a refrigerant flow path 10g connected thereto.

[0017] 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 switching valve 20c is installed on the path of the refrigerant flow path 10k. A pressure reducing device 13c is installed on the path of the refrigerant flow path 10n.

[0018] 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.

[0019] 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.

[0020] 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 the refrigerant flow path 10s connected thereto, a junction 19b, and a refrigerant flow path 10f downstream thereof.

[0021] 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.

[0022] An outlet side 17b of the radiator 17 is connected to an inlet side 15a of the accumulator 15 via a refrigerant flow path 10u, a branch point 18e, a refrigerant flow path 10v, 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 flow path switching valve 20e is provided on the path of the refrigerant flow path 10v.

[0023] 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.

[0024] 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.

[0025] <Battery Temperature Control Circuit> The battery temperature control circuit 40, which serves as a temperature control circuit for an in-vehicle heat-generating device, includes the heat medium passage 14b of the low-temperature side heat exchanger 14 described above and a battery 41, which serves as an example of 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.

[0026] 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.

[0027] 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.

[0028] A circulation pump P40 and a heat medium heater 42 are installed on the heat medium flow path 40b in this order from the upstream side. The heat medium can be circulated by the circulation pump P40. The heat medium heater 42 can heat the heat medium. The temperature of the battery 41 can be adjusted using the heat medium. In this way, the battery temperature control circuit 40, which is an in-vehicle heat-generating device temperature control circuit, is a heat medium circuit in which the heat medium circulates.

[0029] <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.

[0030] 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.

[0031] The cooler core 16 is installed at the upstream side of the air flow passage 120. A heater core passage and a bypass passage are formed in parallel at the downstream side of the air flow passage 120. The heater core 12 is installed in the heater core passage. Therefore, when air introduced into the case 110 is guided to the heater core passage, the air is ventilated through the cooler core 16 and then ventilated to the heater core 12. On the other hand, when air introduced into the case 110 is guided to the bypass passage, 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 and air passing through the bypass passage is adjusted by the air mix damper 150.

[0032] <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.

[0033] The control device 200 controls the operation of various sensors and each part of the vehicle air conditioner 1. The operation of the vehicle air conditioner 1 is controlled by the control device 200 based on the detected values ​​of the various sensors, various requests, etc. 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.

[0034] Detection information from various sensors is input to control device 200. In the hot gas heating mode, detection information from blower air temperature sensor 210, outside air temperature sensor 220, refrigerant temperature sensor 230, refrigerant pressure sensor 240, and heat medium temperature sensor 250 is input to control device 200.

[0035] Based on detection information from various sensors, the control device 200 controls the operation of the flow path switching valves 20, including the flow path switching valves 20c and 20e, to open and close the flow path switching valves 20, thereby selecting a path in the refrigerant circuit 10. While selecting a 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 13, including the pressure reducing devices 13a, 13c, 13d, and 13e, to control the amount of heat released from the refrigerant.

[0036] [Operation of Vehicle Air Conditioner] Specific operations of the vehicle air conditioner 1 according to this embodiment will be described with reference to the drawings.

[0037] 1 shows the basic state of the vehicle air conditioner 1 when the outside temperature is extremely low. At this time, the vehicle interior is heated by executing hot gas heating.

[0038] In the hot gas heating mode, the control device 200 fully closes the pressure reducing devices 13c and 13e and opens the flow path switching valve 20c.

[0039] 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 path 10g and then into the compressor 11. In other words, a circulation path is formed by refrigerant flow paths 10a, 10b, 10j, 10k, 10m, 10r, 10s, 10f, and 10g, in which the refrigerant that has passed through the compressor 11 passes through the heater core 12.

[0040] 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 path 10g and then flows into the compressor 11. In other words, the refrigerant flow paths 10a, 10c, 10d, 10e, 10f, and 10g form a bypass path that allows the refrigerant that has passed through the compressor 11 to bypass the heater core 12.

[0041] 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.

[0042] Because each component of the battery temperature control circuit 40 is exposed to the outside air, the temperature of the heat medium in the battery temperature control circuit 40 and the temperature of the low-temperature side heat exchanger 14 are generally low during startup when the outside air temperature is low. Therefore, as the refrigerant passes through the refrigerant passage 14a of the low-temperature side heat exchanger 14, heat from the refrigerant may be dissipated to the housing of the low-temperature side heat exchanger 14 or to the heat medium in the battery temperature control circuit 40. This heat dissipation may hinder the required increase in refrigerant pressure. Therefore, the vehicle air conditioning system 1 of this embodiment adjusts the operation of the refrigerant circuit 10 according to the temperature of the heat medium in the battery temperature control circuit 40, etc. For example, in the hot gas heating mode, the control device 200 restricts the refrigerant flowing into the low-temperature side heat exchanger 14 when the temperature of the heat medium flowing through the low-temperature side heat exchanger 14 does not satisfy a predetermined condition. Several specific examples of the operation for restricting the refrigerant flowing into the low-temperature side heat exchanger 14 are conceivable, and these are described below.

[0043] (First Example) Fig. 3 is a flowchart showing a first example of a specific control process procedure of the control device 200 at the start of the hot gas heating mode. The first example will be described with reference to the flowchart of Fig. 3 and the circuit diagram of Fig. 1.

[0044] When the outside air temperature is extremely low, the control device 200 activates the hot gas heating mode, and at this time, the control device 200 fully closes the pressure reducing devices 13c and 13e.

[0045] In step S101, the control device 200 determines whether the temperature of the heat medium in the battery temperature control circuit 40 is higher than the temperature of the refrigerant in the refrigerant circuit 10. The temperatures of the heat medium and the refrigerant may be, for example, the respective temperatures at the inlet side of the low-temperature side heat exchanger 14. During startup when the outside air temperature is extremely low, the temperature of the heat medium is low and is often lower than the temperature of the refrigerant. If the temperature of the heat medium is not higher than the temperature of the refrigerant, the process proceeds to step S102.

[0046] In step S102, the control device 200 determines whether the temperature of the heat medium is higher than the outside air temperature by a predetermined temperature. Here, the predetermined temperature may be set appropriately or may be changed depending on various circumstances. At start-up, the temperature of the heat medium is often the outside air temperature. If the temperature of the heat medium is not higher than the outside air temperature by a predetermined temperature, the process proceeds to step S103.

[0047] In step S103, the control device 200 closes the flow path switching valve 20c. As a result, the refrigerant does not flow toward the heater core 12, and therefore does not flow toward the low-temperature side heat exchanger 14. At this time, all of the refrigerant that has passed through the compressor 11 passes through the refrigerant flow paths 10a, 10c, 10d, 10e, 10f, and 10g and then passes through the bypass path that bypasses the heater core 12. Since all of the refrigerant passes through the bypass path, the refrigerant pressure rises quickly. As a result, the start-up time of hot gas operation is shortened.

[0048] In step S104, the control device 200 determines whether to continue the hot gas heating mode based on various conditions. If the hot gas heating mode is to be continued, the process returns to step S101. That is, it is repeatedly determined whether the temperature of the heat medium is higher than the refrigerant temperature and whether it is higher than the outside air temperature by a predetermined temperature. If the temperature of the heat medium is equal to or lower than the refrigerant temperature and is not higher than the outside air temperature by a predetermined temperature, the bypass path continues to be used.

[0049] Eventually, the temperature of the heat medium also rises due to the operation of on-board heat-generating devices such as the battery 41 and the function of the heat medium heater 42. When it is determined in step S102 that the temperature of the heat medium is higher than the outside air temperature by more than a predetermined temperature, the process proceeds to step S105.

[0050] In step S105, the control device 200 opens the flow path switching valve 20c. As a result, the refrigerant flows through the heater core 12. That is, the refrigerant flow paths 10a, 10b, 10j, 10k, 10m, 10r, 10s, 10f, and 10g form a circulation path in which the refrigerant that has passed through the compressor 11 passes through the heater core 12 and the low-temperature side heat exchanger 14. The control device 200 adjusts the throttling amount of the pressure reducing device 13a to allow 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.

[0051] At this time, refrigerant flows through the heater core 12, enabling heating of the vehicle interior. The control device 200 operates the blower 140, enabling heating of the vehicle interior using the heat of the refrigerant dissipated by the heater core 12. The refrigerant flows through the low-temperature side heat exchanger 14. Because the temperature of the refrigerant is equal to or higher than the temperature of the heat medium, the heat of the refrigerant is dissipated to the heat medium side in the low-temperature side heat exchanger 14. However, because the temperature of the heat medium is higher than the outside air temperature by a predetermined temperature, the degree of this heat dissipation is not significant. 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 passing 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.

[0052] In step S106, the control device 200 stops the circulation pump P40, taking into consideration the amount of heat dissipated from the refrigerant to the heat medium. By stopping the circulation pump P40, it is possible to suppress heat dissipation from the refrigerant to the heat medium. If the battery temperature control circuit 40 requires the circulation of the heat medium, the circulation pump P40 may be operated. Furthermore, if the battery temperature control circuit 40 has a switchable flow path, the flow path may be switched as appropriate.

[0053] Next, in step S104, the control device 200 determines whether to continue the hot gas heating mode based on various conditions. If the hot gas heating mode is to be continued, the process returns to step S101. That is, it is repeatedly determined whether the temperature of the heat medium is higher than the refrigerant temperature and whether it is higher than the outside air temperature by a predetermined temperature. If the temperature of the heat medium is equal to or lower than the refrigerant temperature and higher than the outside air temperature by a predetermined temperature, the states of steps S105 and S106 continue.

[0054] For example, if it is necessary to start heating the vehicle interior earlier, the predetermined value used in the determination in step S102 can be reduced to allow the process to proceed to steps S105 and S106 earlier. Also, if it is desired to further suppress heat radiation from the refrigerant in the low-temperature side heat exchanger 14, the predetermined value used in the determination in step S102 can be increased to allow the process in step S103 to continue for a longer period of time. Also, although an example has been shown in which the temperature of the refrigerant is not taken into consideration in the determination in step S102, the temperature of the refrigerant may also be used in the determination.

[0055] As described above, the flow of the refrigerant into the low-temperature side heat exchanger 14 is adjusted according to the temperature of the heat medium, thereby suppressing heat radiation from the refrigerant to the heat medium. As a result, the start-up time of the hot gas operation is shortened.

[0056] Eventually, the temperature of the heat medium may further increase due to the operation of on-board heat-generating devices such as the battery 41 and the function of the heat medium heater 42. When it is determined in step S101 that the temperature of the heat medium is higher than the temperature of the refrigerant, the process proceeds to step S107.

[0057] In step S107, the control device 200 opens the flow path switching valve 20c, as in step S105, and causes the refrigerant to flow through the heater core 12 and the low-temperature side heat exchanger 14. In step S108, the control device 200 operates the circulation pump P40. Because the temperature of the heat medium is higher than that of the refrigerant, the refrigerant absorbs heat from the heat medium. As a result, the start-up time of the hot gas operation is shortened. Furthermore, because the refrigerant absorbs heat from the heat medium, the rotation speed of the compressor 11 can be reduced accordingly, thereby reducing noise and power consumption.

[0058] Next, in step S104, the control device 200 determines whether to continue the hot gas heating mode based on various conditions. If the hot gas heating mode is to be continued, the process returns to step S101, and the hot gas heating mode is continued. If the hot gas heating mode is not to be continued, the process for the hot gas heating mode ends.

[0059] The above-described operation allows the refrigerant pressure to increase quickly when hot gas operation starts, enabling the HVAC unit 100 to quickly achieve the target outlet temperature. In other words, rapid heating is achieved. Furthermore, noise and power consumption by the compressor 11 can be reduced.

[0060] Although the above example is a case where the determination is made using the value of the heat medium temperature, this is not limiting. For example, the determination may be made using the temperature difference between the temperature of the heat medium at the inlet side and the temperature of the heat medium at the outlet side of the low-temperature side heat exchanger 14. When the refrigerant flows through the low-temperature side heat exchanger 14 and heat is dissipated to the heat medium, the temperature of the heat medium at the outlet side becomes higher than the temperature of the heat medium at the inlet side of the low-temperature side heat exchanger 14, and the greater the degree of heat dissipation, the greater this temperature difference becomes. Therefore, when the temperature of the heat medium at the outlet side of the low-temperature side heat exchanger 14 becomes higher than the temperature of the heat medium at the inlet side by more than a predetermined value, the flow of refrigerant into the low-temperature side heat exchanger 14 may be restricted or the operation of the circulation pump P40 may be stopped.

[0061] In the first example, for example, when the heat medium in the battery temperature control circuit 40 has cooled to approximately the same temperature as the outside air temperature, the operation sequence is as described above. On the other hand, there are cases where the temperature of an on-board heat-generating device such as the battery 41 is higher than the outside air temperature or the refrigerant temperature, for example, when the battery 41 is being charged before startup or when not much time has passed since the vehicle was shut down and the heat medium has not yet cooled. In such cases, in the first example, the refrigerant immediately flows through the low-temperature side heat exchanger 14 upon startup, and in some cases, the refrigerant absorbs heat from the heat medium in the battery temperature control circuit 40. As a result, the refrigerant pressure rises quickly when hot gas operation starts, resulting in rapid heating.

[0062] (Second Example) In the first example described above, when the temperature of the heat medium in the battery temperature control circuit 40 is very low, the refrigerant bypasses the heater core 12 and the low-temperature side heat exchanger 14 and uses only the bypass path. In the second example, the refrigerant that has passed through the heater core 12 bypasses the low-temperature side heat exchanger 14 and passes through the cooler core 16. FIG. 4 is a flowchart showing a second example of the specific control processing procedure of the control device 200 when starting up the hot gas heating mode. The second example will be described with reference to the flowchart of FIG. 4 and the circuit diagram of FIG. 5. Note that some of the descriptions common to the first example will be omitted. The above descriptions may also be applied to the second example to the extent that there is no contradiction.

[0063] When the outside air temperature is extremely low, the control device 200 activates the hot gas heating mode. At this time, the control device 200 fully closes the pressure reducing device 13e and opens the flow path switching valve 20c.

[0064] In step S201, the control device 200 determines whether the temperature of the heat medium in the battery temperature control circuit 40 is higher than the temperature of the refrigerant in the refrigerant circuit 10. If the temperature of the heat medium is not higher than the temperature of the refrigerant, the process proceeds to step S202.

[0065] In step S202, the control device 200 determines whether the temperature of the heat medium is higher than the outside air temperature by more than a predetermined temperature. If the temperature of the heat medium is not higher than the outside air temperature by more than the predetermined temperature, the process proceeds to step S203.

[0066] In step S203, the control device 200 closes the pressure reducing device 13d and opens the pressure reducing device 13c. As a result, as shown in FIG. 5 , the refrigerant does not flow toward the low-temperature side heat exchanger 14 but flows through the cooler core 16. That is, the refrigerant flow paths 10a, 10b, 10j, 10k, 10m, 10n, 10p, 10q, 10e, 10f, and 10g form a circulation path through which the refrigerant that has passed through the compressor 11 passes through the heater core 12 and the cooler core 16. The control device 200 adjusts the throttling 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 cooler core 16 and cause the remaining refrigerant to flow through the bypass path.

[0067] In step S204, the control device 200 stops the blower 140. This is because blowing air to the cooler core 16 and the heater core 12 while refrigerant is flowing through both the heater core 12 on the upstream side of the pressure reducing device 13c and the cooler core 16 on the downstream side is not appropriate for the operation of the refrigerant circuit 10.

[0068] In this way, the refrigerant does not flow through the low-temperature side heat exchanger 14, which is already as cold as the outside air temperature. Therefore, the refrigerant does not radiate heat to the housing of the low-temperature side heat exchanger 14 or the heat medium. For example, when restarting operation after a relatively short parking period, the interior of the vehicle, where the cooler core 16 is located, may be hotter than the motor compartment, where the low-temperature side heat exchanger 14 is located. In such cases, the effect of flowing the refrigerant through the cooler core 16, as in this example, is significant. According to this example, by bypassing the low-temperature low-temperature side heat exchanger 14, the refrigerant pressure easily increases, which may shorten the start-up time for hot gas operation. Furthermore, if the temperature inside the vehicle, where the cooler core 16 is located, is as cold as the motor compartment, where the low-temperature side heat exchanger 14 is located, the refrigerant flowing through the cooler core 16 may radiate heat to the same extent as if it had flowed through the low-temperature side heat exchanger 14. However, the heat radiated from the cooler core 16 preheats the HVAC unit 100. This operation can be considered a warm-up operation of the HVAC unit 100. In this case, as will be described later, a drop in refrigerant pressure due to heat radiation from the heater core 12 that may occur when the blower 140 starts operating can be suppressed, and the start-up time of hot gas operation can be shortened. In other words, heat is used efficiently overall.

[0069] In step S205, the control device 200 determines whether to continue the hot gas heating mode based on various conditions. If the hot gas heating mode is to be continued, the process returns to step S201. That is, it is repeatedly determined whether the temperature of the heat medium is higher than the refrigerant temperature and whether it is higher than the outside air temperature by a predetermined temperature. When the temperature of the heat medium is equal to or lower than the refrigerant temperature and is not higher than the outside air temperature by a predetermined temperature, the flow path passing through the cooler core 16 continues to be used.

[0070] When it is determined in step S202 that the temperature of the heat medium is higher than the outside air temperature by more than a predetermined temperature, the process proceeds to step S206. In step S206, the control device 200 closes the pressure reducing device 13c and opens the pressure reducing device 13d. As a result, as shown in FIG. 1 , the refrigerant flows through the low-temperature side heat exchanger 14 without flowing toward the cooler core 16. That is, the refrigerant flow paths 10a, 10b, 10j, 10k, 10m, 10r, 10s, 10f, and 10g form a circulation path in which the refrigerant that has passed through the compressor 11 passes through the heater core 12 and the low-temperature side heat exchanger 14. The control device 200 adjusts the throttling amount of the pressure reducing device 13a to cause a portion of the refrigerant discharged from the compressor 11 to flow toward the heater core 12 and the remaining refrigerant to flow toward the bypass path.

[0071] In step S207, the control device 200 operates the blower 140 to enable indoor heating using the heat of the refrigerant dissipated in the heater core 12. As described above, the heat dissipated when the refrigerant was flowing through the cooler core 16 can also be utilized during this air-conditioning operation.

[0072] The refrigerant flows through the low-temperature side heat exchanger 14. Because the temperature of the refrigerant is equal to or higher than the temperature of the heat medium, the heat of the refrigerant is dissipated to the heat medium side in the low-temperature side heat exchanger 14. However, because the temperature of the heat medium is higher than the outside air temperature by a predetermined temperature, the degree of this heat dissipation is not significant. On the other hand, 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 passing 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.

[0073] In step S208, the control device 200 stops the circulation pump P40, taking into consideration the amount of heat dissipated from the refrigerant to the heat medium. By stopping the circulation pump P40, it is possible to suppress heat dissipation from the refrigerant to the heat medium.

[0074] Next, in step S205, the control device 200 determines whether to continue the hot gas heating mode based on various conditions, and if the hot gas heating mode is to be continued, the process returns to step S201. If the temperature of the heat medium is equal to or lower than the refrigerant temperature and is higher than the outside air temperature by a predetermined temperature, the states of steps S206 to S208 continue.

[0075] Since the flow of the refrigerant into the low-temperature side heat exchanger 14 is adjusted according to the temperature of the heat medium, heat radiation from the refrigerant to the heat medium is suppressed, resulting in a faster start-up time for hot gas operation.

[0076] If it is determined in step S201 that the temperature of the heat medium is higher than the temperature of the refrigerant, the process proceeds to step S209. In step S209, the control device 200 causes the refrigerant to flow through the heater core 12 and the low-temperature side heat exchanger 14. In step S210, the control device 200 operates the circulation pump P40. Because the temperature of the heat medium is higher than the temperature of the refrigerant, the refrigerant absorbs heat from the heat medium. As a result, the start-up time of the hot gas operation is shortened. Furthermore, because the refrigerant absorbs heat from the heat medium, the rotation speed of the compressor 11 can be reduced accordingly, thereby reducing noise and power consumption.

[0077] Next, in step S205, the control device 200 determines whether to continue the hot gas heating mode based on various conditions. If the hot gas heating mode is to be continued, the process returns to step S201, and the hot gas heating mode is continued. If the hot gas heating mode is not to be continued, the process for the hot gas heating mode ends.

[0078] The above-described operation allows the refrigerant pressure to increase quickly when hot gas operation starts, enabling the HVAC unit 100 to quickly achieve the target outlet temperature. In other words, rapid heating is achieved. Furthermore, noise and power consumption by the compressor 11 can be reduced.

[0079] (Third Example) In the second example described above, when the temperature of the heat medium in the battery temperature control circuit 40 is very low, the refrigerant that has passed through the heater core 12 bypasses the low-temperature side heat exchanger 14 and passes through the cooler core 16. In the third example, as shown in FIG. 6 , the refrigerant circuit 10 is provided with a refrigerant flow path 10x that bypasses the low-temperature side heat exchanger 14.

[0080] More specifically, a three-way valve V31 is provided in a refrigerant flow path 10r leading from the pressure reducing device 13d to the refrigerant passage 14a of the low-temperature side heat exchanger 14. One side of the three-way valve V31, to which the refrigerant flow path 10r is connected, connects the refrigerant flow path 10r to a refrigerant flow path 10y in which the low-temperature side heat exchanger 14 is disposed. The other side of the three-way valve V31, to which the refrigerant flow path 10r is connected, connects the refrigerant flow path 10r to a junction 19f of a refrigerant flow path 10s leading to the accumulator 15, which is a refrigerant flow path 10x that bypasses the low-temperature side heat exchanger 14. A check valve 21d is provided on the refrigerant flow path 10y connecting the low-temperature side heat exchanger 14 and the junction 19f to prevent backflow of refrigerant to the low-temperature side heat exchanger 14.

[0081] Fig. 7 is a flowchart showing a third example of the specific control processing procedure of the control device 200 when starting the hot gas heating mode. The third example will be described with reference to the flowchart of Fig. 7 and the circuit diagram of Fig. 6. Note that some of the explanations common to the first example will be omitted. The above explanations can also be applied to the third example to the extent that there is no contradiction.

[0082] When the outside air temperature is extremely low, the control device 200 activates the hot gas heating mode. At this time, the control device 200 fully closes the pressure reducing devices 13c and 13e and opens the flow path switching valve 20c.

[0083] In step S301, the control device 200 determines whether the temperature of the heat medium in the battery temperature control circuit 40 is higher than the temperature of the refrigerant in the refrigerant circuit 10. When the temperature of the heat medium is not higher than the temperature of the refrigerant, the process proceeds to step S302.

[0084] In step S302, the control device 200 switches the three-way valve V31 so that the refrigerant flows through the bypass refrigerant flow path 10x without flowing through the low-temperature side heat exchanger 14. As a result, as shown in Fig. 6, the refrigerant flow paths 10a, 10b, 10j, 10k, 10m, 10r, 10x, 10s, 10f, and 10g form a circulation path in which the refrigerant that has passed through the compressor 11 passes through the heater core 12 and bypasses the low-temperature side heat exchanger 14. The control device 200 adjusts the throttling 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.

[0085] Because the refrigerant does not flow toward the low-temperature side heat exchanger 14, where the temperature is as low as the outside air temperature, the refrigerant does not radiate heat to the housing or heat medium of the low-temperature side heat exchanger 14. As a result, the pressure of the refrigerant is likely to increase, which can shorten the start-up time of hot gas operation.

[0086] In step S303, the control device 200 determines whether to continue the hot gas heating mode based on various conditions. If the hot gas heating mode is to be continued, the process returns to step S301. That is, it is repeatedly determined whether the temperature of the heat medium is higher than the refrigerant temperature. When the temperature of the heat medium is equal to or lower than the refrigerant temperature, the refrigerant continues to bypass the low-temperature side heat exchanger 14.

[0087] When it is determined in step S301 that the temperature of the heat medium is higher than the temperature of the refrigerant, the process proceeds to step S304. In step S304, the control device 200 switches the three-way valve V31 so that the refrigerant flows through the low-temperature side heat exchanger 14. As a result, a circulation path is formed by the refrigerant flow paths 10a, 10b, 10j, 10k, 10m, 10r, 10y, 10s, 10f, and 10g, in which the refrigerant that has passed through the compressor 11 passes through the heater core 12 and the low-temperature side heat exchanger 14. The control device 200 adjusts the throttling 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.

[0088] In step S305, the control device 200 operates the circulation pump P40. Because the temperature of the heat medium is higher than that of the refrigerant, the refrigerant absorbs heat from the heat medium. As a result, the start-up time of the hot gas operation is shortened.

[0089] Next, in step S303, control device 200 determines whether to continue the hot gas heating mode based on various conditions. If the hot gas heating mode is to be continued, the process returns to step S301, and the hot gas heating mode is continued. If the hot gas heating mode is not to be continued, the process for the hot gas heating mode ends.

[0090] The above-described operation allows the refrigerant pressure to increase quickly when hot gas operation starts, enabling the HVAC unit 100 to quickly achieve the target outlet temperature. In other words, rapid heating is achieved. Furthermore, noise and power consumption by the compressor 11 can be reduced.

[0091] The operations of the first to third examples described above can be combined as appropriate. That is, depending on conditions such as the temperature of the heat medium in the battery temperature control circuit 40 and the pressure and temperature of the refrigerant, the control device 200, for example, causes the refrigerant to bypass the heater core 12, flow through the heater core 12 and the cooler core 16, flow through the heater core 12 while bypassing the low-temperature side heat exchanger 14, or flow through the heater core 12 and the low-temperature side heat exchanger 14. The control device 200 also circulates or does not circulate the heat medium in the battery temperature control circuit 40. By appropriately combining these, the control device 200 can speed up the start-up of hot gas operation and achieve fast warm-up.

[0092] [Regarding the Vehicle Air Conditioner] The vehicle air conditioner 1 of this embodiment can achieve the following effects.

[0093] (a1) The vehicle air conditioning system 1 includes a compressor 11, a heater core 12 configured to heat air supplied to a vehicle cabin, a pressure reducing device 13, and a low-temperature side heat exchanger 14 configured to exchange heat between a heat medium that exchanges heat with an on-board heat-generating device and a refrigerant, and is equipped with a refrigerant circuit 10 having a path configured to circulate the refrigerant between the compressor 11, the heater core 12, the pressure reducing device 13d, and the low-temperature side heat exchanger 14, and 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 of the compressor. The vehicle air conditioning system 1 further includes a heat medium circuit, such as a battery temperature control circuit 40, configured to circulate the heat medium between an on-board heat-generating device such as a battery 41 and the low-temperature side heat exchanger 14, and a control device 200 configured to switch and control the refrigerant circuit 10, and capable of control in a hot gas heating mode in which a portion of the refrigerant that has passed through the compressor 11 flows to the heater core 12 and the remaining refrigerant flows through the bypass path. In the hot gas heating mode, when the temperature of the heat medium flowing through the low-temperature side heat exchanger 14 does not satisfy a predetermined condition, the control device 200 restricts the inflow of refrigerant into the low-temperature side heat exchanger 14 .

[0094] As a result, the vehicle air conditioning system 1 of this embodiment can shorten the time required to reach the target heating capacity. For example, when the temperature of the refrigerant flowing through the low-temperature side heat exchanger 14 is higher than the temperature of the heat medium flowing through the low-temperature side heat exchanger 14, the refrigerant radiates heat to the heat medium. In such a case, the temperature of the refrigerant on the suction side of the compressor 11 drops, making it difficult for the refrigerant to reach an appropriate state, and lengthening the time required to reach the target heating capacity. In response to this, the vehicle air conditioning system 1 of this embodiment restricts the inflow of refrigerant into the low-temperature side heat exchanger 14 until the temperature of the heat medium flowing through the low-temperature side heat exchanger 14 becomes higher than the temperature of the refrigerant flowing through the low-temperature side heat exchanger 14. This prevents heat radiation from the refrigerant to the heat medium, suppresses a temperature drop in the refrigerant, and improves the temperature rise of the refrigerant. As a result, the time required to reach the target heating capacity can be shortened, and rapid heating can be improved.

[0095] (a2) For example, when the hot gas heating mode is started, the control device 200 restricts the flow of refrigerant into the low-temperature side heat exchanger 14 until the temperature of the heat medium flowing through the low-temperature side heat exchanger 14 exceeds a predetermined reference temperature.

[0096] As a result, the automotive air conditioning system 1 of this embodiment can shorten the time required to reach the target heating capacity at startup in the hot gas heating mode. At startup, it is assumed that the entire system is at a temperature close to the outside air temperature. The automotive air conditioning system 1 of this embodiment is particularly effective at startup. The reference temperature may be a predetermined temperature, the temperature of the refrigerant flowing through the low-temperature side heat exchanger 14, or a value higher than the outside air temperature by a predetermined temperature.

[0097] (a3) A heat medium circuit such as the battery temperature control circuit 40 may further include a heat medium heater 42 configured to heat the heat medium.

[0098] By heating the heat medium with the heat medium heater 42, the temperature of the heat medium can be increased in a shorter time. This reduces the time required for the temperature of the heat medium to satisfy a predetermined condition. In addition, heat radiation from the refrigerant to the heat medium can be further suppressed. As a result, the time required to reach the target heating capacity can be shortened, and quick heating can be improved.

[0099] (a4) The heat medium circuit may further include a circulation pump P40 configured to circulate the heat medium, and the control device 200 may be configured to control the operation or stop of the circulation pump P40 based on the temperature of the heat medium in the hot gas heating mode.

[0100] When the temperature of the heat medium is lower than the temperature of the refrigerant, heat from the refrigerant may be dissipated to the heat medium in the low-temperature side heat exchanger 14. In this case, this heat dissipation can be suppressed by stopping the circulation pump P40 to stop the circulation of the heat medium. When the temperature of the heat medium is higher than the temperature of the refrigerant, the refrigerant may absorb heat from the heat medium in the low-temperature side heat exchanger 14. In this case, the efficiency of this heat absorption can be improved by circulating the heat medium, which operates the circulation pump P40. Both of these contribute to shortening the time required to reach the target heating capacity and improving quick heating.

[0101] (a5) When the temperature of the heat medium flowing through the low-temperature side heat exchanger 14, for which the control device 200 regulates the inflow of refrigerant into the low-temperature side heat exchanger 14, does not satisfy a predetermined condition, for example, when the temperature of the heat medium flowing through the low-temperature side heat exchanger 14 does not exceed a predetermined reference temperature, when the temperature of the heat medium flowing through the low-temperature side heat exchanger 14 is not higher than the outside air temperature by a predetermined temperature, when the temperature difference between the temperature of the heat medium at the outlet side and the temperature of the heat medium at the inlet side of the low-temperature side heat exchanger 14 exceeds a predetermined value, or when the temperature of the heat medium flowing through the low-temperature side heat exchanger 14 does not exceed the temperature of the refrigerant flowing through the low-temperature side heat exchanger 14.

[0102] The predetermined reference temperature may be set, for example, to a temperature low enough to delay achievement of the target heating capacity. By restricting the inflow of refrigerant into the low-temperature side heat exchanger 14 when the temperature of the heat medium flowing through the low-temperature side heat exchanger 14 does not exceed the predetermined reference temperature, heat loss can be suppressed and delay in achievement of the target heating capacity can be prevented. Furthermore, the temperature higher than the outside air temperature by a predetermined temperature may be set, for example, to a temperature low enough to delay achievement of the target heating capacity. By restricting the inflow of refrigerant into the low-temperature side heat exchanger 14 when the temperature of the heat medium flowing through the low-temperature side heat exchanger 14 is not higher than the outside air temperature by more than the predetermined temperature, heat loss can be suppressed and delay in achievement of the target heating capacity can be prevented. When the temperature difference between the temperature of the heat medium at the outlet side and the temperature of the heat medium at the inlet side of the low-temperature side heat exchanger 14 exceeds a predetermined value, a large amount of heat is dissipated from the refrigerant to the heat medium. By restricting the inflow of refrigerant into the low-temperature side heat exchanger 14 when the temperature difference between the temperature of the heat medium at the outlet side and the temperature of the heat medium at the inlet side of the low-temperature side heat exchanger 14 exceeds a predetermined value, heat loss can be suppressed and delays in achieving the target heating capacity can be prevented. When the temperature of the heat medium flowing through the low-temperature side heat exchanger 14 does not exceed the temperature of the refrigerant flowing through the low-temperature side heat exchanger 14, heat radiation from the refrigerant to the heat medium can occur. By restricting the inflow of refrigerant into the low-temperature side heat exchanger 14 when the temperature of the heat medium flowing through the low-temperature side heat exchanger 14 does not exceed the temperature of the refrigerant flowing through the low-temperature side heat exchanger 14, heat loss can be suppressed, delays in achieving the target heating capacity can be prevented, and quick heating can be improved.

[0103] (a6) For example, when the temperature of the heat medium flowing through the low-temperature side heat exchanger 14 does not satisfy a predetermined condition, the control device 200 causes all of the refrigerant that has passed through the compressor 11 to flow through the bypass path.

[0104] This suppresses heat radiation from the refrigerant in the heater core 12 and also suppresses heat radiation from the refrigerant in the low-temperature side heat exchanger 14. As a result, the time required to reach the target heating capacity can be shortened, and quick heating can be improved.

[0105] (a7) The refrigerant circuit 10 includes a cooler core 16 configured to exchange heat with air supplied to the vehicle cabin and arranged downstream of the pressure reducing device 13c, and the control device 200 may flow at least a portion of the refrigerant that has passed through the compressor 11 to the heater core 12, the pressure reducing device 13c, and the cooler core 16 when the temperature of the heat medium flowing through the low-temperature side heat exchanger 14 does not satisfy a predetermined condition.

[0106] As a result, heat is dissipated from the refrigerant in the cooler core 16 rather than in the low-temperature side heat exchanger 14, and the air inside the HVAC unit 100 is preheated. As a result, the load on the heater core 12 when the blower 140 starts blowing thereafter is reduced, and a decrease in refrigerant pressure on the outlet side of the heater core 12 that may occur when blowing starts is reduced. As a result, the time required to reach the target heating capacity can be shortened, and quick heating can be improved.

[0107] (a8) The refrigerant circuit 10 has a refrigerant flow path 10x that functions as a low-temperature side heat exchanger bypass flow path that bypasses the low-temperature side heat exchanger 14, and the control device 200 may, when the temperature of the heat medium flowing through the low-temperature side heat exchanger 14 does not satisfy a predetermined condition, flow at least a portion of the refrigerant that has passed through the compressor 11 into the heater core 12, the pressure reducing device 13d, and the low-temperature side heat exchanger bypass flow path.

[0108] This makes it possible to suppress heat radiation from the refrigerant in the low-temperature side heat exchanger 14. As a result, the time required to reach the target heating capacity can be shortened, and quick heating can be improved.

[0109] (b1) The vehicle air conditioning device 1 includes a compressor 11, a heater core 12 configured to heat the air supplied to the vehicle cabin, a pressure reducing device 13, a cooler core 16 configured to cool the air supplied to the vehicle cabin, and a low-temperature side heat exchanger 14 configured to exchange heat with a refrigerant, and is equipped with a refrigerant circuit 10 having a path configured to circulate the refrigerant between the compressor 11, the heater core 12, the pressure reducing device 13d, and the low-temperature side heat exchanger 14, a path configured to circulate the refrigerant between the compressor 11, the heater core 12, the pressure reducing device 13c, and the cooler core 16, and 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 of the compressor 11. The vehicle air conditioner 1 further includes an HVAC unit 100 as an air conditioning unit having a heater core 12, a cooler core 16, and a blower 140 that blows air into the vehicle cabin, and a control device 200 that is configured to control the operation of the blower 140, that is configured to switch and control the refrigerant circuit 10, and that is capable of control in a hot gas heating mode in which a portion of the refrigerant that has passed through the compressor 11 flows to the heater core 12 and the remaining refrigerant flows to a bypass path. In the hot gas heating mode, the control device 200 is capable of control in a warm-up operation in which the refrigerant is circulated through the compressor 11, the heater core 12, the pressure reducing device 13c, and the cooler core 16, and blowing by the blower 140 is prohibited.

[0110] As a result, the vehicle air conditioning system 1 of this embodiment can shorten the time required to reach the target heating capacity. For example, when the temperature of the heat medium flowing through the low-temperature side heat exchanger 14 is low, the refrigerant radiates heat to the heat medium. In such a case, the temperature of the refrigerant on the suction side of the compressor 11 drops, the refrigerant state does not reach an appropriate state, and the time required to reach the target heating capacity increases. In response to this, the vehicle air conditioning system 1 of this embodiment prevents heat radiation from the refrigerant to the heat medium by, for example, suppressing the inflow of refrigerant into the low-temperature side heat exchanger 14 until the temperature of the heat medium flowing through the low-temperature side heat exchanger 14 rises to a certain level. As a result, the refrigerant temperature decrease is suppressed, the refrigerant temperature increase is improved, the time required to reach the target heating capacity is shortened, and the heating speed is improved. Furthermore, the refrigerant radiates heat in the cooler core 16 rather than the low-temperature side heat exchanger 14, thereby preheating the air in the HVAC unit 100. As a result, the load on the heater core 12 when the blower 140 starts blowing thereafter can be reduced, and a decrease in refrigerant pressure at the outlet side of the heater core 12 that may occur when blowing starts can be reduced. This also improves the rise in refrigerant temperature, shortens the time required to reach the target heating capacity, and improves quick heating. When refrigerant is flowing through the heater core 12 and the cooler core 16, the blower 140 is stopped to prevent a breakdown in the cycle of the refrigerant circuit 10.

[0111] (b2) The control device 200 can control air conditioning operation, for example, in hot gas heating mode, by circulating the refrigerant through the compressor 11, heater core 12, pressure reducing device 13d, and low-temperature side heat exchanger 14 after preparatory operation, and then allowing the blower 140 to blow air.

[0112] By changing the refrigerant flow path from the cooler core 16 to the low-temperature side heat exchanger 14 before starting the blower 140, it is possible to suppress a decrease in the temperature of the refrigerant on the suction side of the compressor 11. This makes it possible to avoid a reduction in the hot gas cycle.

[0113] (c1) The vehicle air conditioning device 1 includes a compressor 11, a heater core 12 configured to heat air supplied to a vehicle cabin, a pressure reducing device 13d, a low-temperature side heat exchanger 14 configured to exchange heat with a refrigerant, and a refrigerant flow path 10x that functions as a low-temperature side heat exchanger bypass flow path that bypasses the low-temperature side heat exchanger 14, and includes a refrigerant circuit having a path configured to circulate the refrigerant between the compressor 11, the heater core 12, the pressure reducing device 13d, and the low-temperature side heat exchanger 14, a path configured to circulate the refrigerant between the compressor 11, the heater core 12, the pressure reducing device 13d, and the low-temperature side heat exchanger bypass flow path, and 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 of the compressor 11. The vehicle air conditioning device 1 further includes a control device that is configured to switch and control the refrigerant circuit 10, and is capable of control in a hot gas heating mode in which a portion of the refrigerant that has passed through the compressor 11 flows to the heater core 12 and the remaining refrigerant flows to the bypass path. In the hot gas heating mode, the control device 200 can control the refrigerant to circulate through the compressor 11, the heater core 12, the pressure reducing device 13d, and the low-temperature side heat exchanger bypass flow path, thereby bypassing the low-temperature side heat exchanger 14.

[0114] As a result, the vehicle air conditioning system 1 of this embodiment can shorten the time required to reach the target heating capacity. For example, when the temperature of the heat medium flowing through the low-temperature side heat exchanger 14 is low, the refrigerant dissipates heat to the heat medium. In such a case, the temperature of the refrigerant on the suction side of the compressor 11 drops, the refrigerant does not reach an appropriate state, and the time required to reach the target heating capacity increases. In response to this, the vehicle air conditioning system 1 of this embodiment prevents heat dissipation from the refrigerant to the heat medium by, for example, suppressing the inflow of refrigerant into the low-temperature side heat exchanger 14 until the temperature of the heat medium flowing through the low-temperature side heat exchanger 14 rises to a certain level. As a result, the decrease in refrigerant temperature is suppressed, the refrigerant temperature rise is improved, the time required to reach the target heating capacity is shortened, and quick heating performance can be improved.

[0115] (c2) The refrigerant circuit 10 may further include a check valve 21d provided to prevent the refrigerant that has flowed through the low-temperature side heat exchanger bypass passage from flowing back into the low-temperature side heat exchanger 14.

[0116] This makes it possible to suppress a decrease in the pressure of the refrigerant on the suction side of the compressor 11 that may occur when the refrigerant flows back into the low-temperature side heat exchanger 14 .

[0117] (c3) The low-temperature side heat exchanger 14 is configured to exchange heat between the refrigerant and a heat medium that exchanges heat with an on-board heat-generating device such as the battery 41, and in the hot gas heating mode, when the temperature of the heat medium flowing through the low-temperature side heat exchanger 14 does not exceed the temperature of the refrigerant, the control device 200 may circulate the refrigerant through the compressor 11, the heater core 12, the pressure reducing device 13d, and the low-temperature side heat exchanger bypass flow path to bypass the low-temperature side heat exchanger 14.

[0118] This makes it possible to suppress heat radiation from the refrigerant in the low-temperature side heat exchanger 14. That is, when the temperature of the heat medium flowing through the low-temperature side heat exchanger 14 is equal to or lower than the temperature of the refrigerant flowing through the low-temperature side heat exchanger 14, the refrigerant will radiate heat to the heat medium. By bypassing the low-temperature side heat exchanger 14 and flowing through the low-temperature side heat exchanger bypass flow path, it is possible to suppress such heat radiation from the refrigerant. As a result, the time required to reach the target heating capacity can be shortened, and quick heating can be improved.

[0119] 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.

[0120] 1: Vehicle air conditioning system 10: Refrigerant circuit, 11: Compressor, 12: Heater core, 13, 13a, 13c, 13d, 13e: Pressure reducing device, 14: Low temperature side heat exchanger, 15: Accumulator, 16: Cooler core, 17: Radiator, 20, 20c, 20e: Flow path switching valve 40: Battery temperature control circuit, 41: Battery, 42: Heat medium heating device, P40: Circulation pump 100: HVAC unit, 110: Case, 120: Air flow passage, 140: Blower, 150: Air mix damper

Claims

1. An air conditioning system for a vehicle comprising: a compressor, a heater core configured to heat air to be supplied into a vehicle cabin, a pressure reducing device, and a low-temperature side heat exchanger configured to exchange heat between a refrigerant and a heat medium that exchanges heat with an on-board heat-generating device, said refrigerant circuit having a path configured to circulate the refrigerant between the compressor, the heater core, the pressure reducing device, and the low-temperature side heat exchanger, and a bypass path through which the refrigerant that has passed through the compressor bypasses the heater core and flows into the suction side of the compressor; a heat medium circuit configured to circulate the heat medium between the on-board heat-generating device and the low-temperature side heat exchanger; and a control device configured to switch and control the refrigerant circuit, and capable of control in 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 in the hot gas heating mode, the control device restricts the flow of the refrigerant into the low-temperature side heat exchanger when the temperature of the heat medium flowing through the low-temperature side heat exchanger does not satisfy a predetermined condition.

2. The vehicle air conditioning system of claim 1, wherein the control device restricts the flow of the refrigerant into the low-temperature side heat exchanger when the hot gas heating mode is activated until the temperature of the heat medium flowing through the low-temperature side heat exchanger exceeds a predetermined reference temperature.

3. The vehicle air conditioning system according to claim 1 or 2, wherein the heat medium circuit further comprises a heat medium heating device configured to heat the heat medium.

4. A vehicle air conditioning system as described in claim 1 or 2, wherein the heat medium circuit further includes a circulation pump configured to circulate the heat medium, and the control device is configured to control operation or stop of the circulation pump based on the temperature of the heat medium in the hot gas heating mode.

5. The vehicle air conditioning system of claim 1, wherein the control device regulates the inflow of the refrigerant into the low-temperature side heat exchanger when the temperature of the heat medium flowing through the low-temperature side heat exchanger does not satisfy a predetermined condition, when the temperature of the heat medium flowing through the low-temperature side heat exchanger does not exceed a predetermined reference temperature, when the temperature of the heat medium flowing through the low-temperature side heat exchanger is not higher than the outside air temperature by a predetermined temperature, when the temperature difference between the temperature of the heat medium at the outlet side and the temperature of the heat medium at the inlet side of the low-temperature side heat exchanger exceeds a predetermined value, or when the temperature of the heat medium flowing through the low-temperature side heat exchanger does not exceed the temperature of the refrigerant flowing through the low-temperature side heat exchanger.

6. The vehicle air conditioning system according to claim 1 or 2, wherein the control device causes all of the refrigerant that has passed through the compressor to flow through the bypass path when the temperature of the heat medium flowing through the low-temperature side heat exchanger does not satisfy a predetermined condition.

7. A vehicle air conditioning system as described in claim 1 or 2, wherein the refrigerant circuit includes a cooler core configured to exchange heat with air supplied to the vehicle cabin and disposed downstream of a pressure reducing device, and the control device causes at least a portion of the refrigerant that has passed through the compressor to flow through the heater core, the pressure reducing device and the cooler core when the temperature of the heat medium flowing through the low-temperature side heat exchanger does not satisfy a predetermined condition.

8. An air conditioning system for a vehicle as described in claim 1 or 2, wherein the refrigerant circuit has a low-temperature side heat exchanger bypass flow path that bypasses the low-temperature side heat exchanger, and the control device, when the temperature of the heat medium flowing through the low-temperature side heat exchanger does not satisfy a predetermined condition, causes at least a portion of the refrigerant that has passed through the compressor to flow through the heater core, the pressure reducing device, and the low-temperature side heat exchanger bypass flow path.

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