Air conditioner for vehicle

Abstract

To provide an air conditioner for a vehicle capable of preventing failure of a compressor and preventing enlargement of an accumulator.SOLUTION: The refrigerant circuit 10 has a storage mode in which surplus refrigerant is stored in a case where surplus refrigerant is generated in the refrigerant circuit 10, and when refrigerant shortage is detected after the execution of the storage mode is completed, the flow path opening and closing valve 20d on the downstream side of the low-temperature side heat exchanger 14 or the flow path opening and closing valve 20e on the downstream side of the outdoor heat exchanger 17, which is set as the storage portion, is opened.SELECTED DRAWING: Figure 1

Description

[Technical Field]

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

[0002] Air conditioners using heat pumps are known for use in electric vehicles (EVs) that do not have a combustion-based heat source such as an engine, or in vehicles with a low heat output from a combustion-based heat source. However, in air conditioners using heat pumps, the efficiency of the refrigeration cycle decreases when the refrigerant circulation rate fluctuates due to switching of the refrigerant flow path. For this reason, Patent Document 1, for example, discloses a technology for storing excess refrigerant in a heat exchanger that is not performing heat exchange. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 4822874 Summary of the Invention [Problem to be solved by the invention]

[0004] SUMMARY OF THE INVENTION An object of the present invention is to provide a vehicle air conditioner that can prevent compressor failure and prevent the accumulator from becoming large. [Means for solving the problem]

[0005] According to one aspect of the present invention, a vehicle air conditioning system is provided with a refrigerant circuit having a plurality of heat exchangers and valve devices arranged upstream and downstream of each of the plurality of heat exchangers, in which a heat exchanger that does not actively perform heat exchange is used as a storage section for storing excess refrigerant generated in the refrigerant circuit, and has a storage mode in which excess refrigerant in an air conditioning operating mode is stored in the storage section, and when a refrigerant shortage in the refrigerant circuit is detected after the storage mode has ended, the valve device downstream of the heat exchanger used as the storage section is opened. [Effects of the Invention]

[0006] SUMMARY OF THE INVENTION An object of the present invention is to provide a vehicle air conditioner that can prevent compressor failure and prevent the accumulator from becoming large. [Brief explanation of the drawings]

[0007] [Figure 1] FIG. 1 is a diagram showing an outline of an example of the configuration of a vehicle air conditioner, and is a diagram showing an example of the state of the vehicle air conditioner when a storage mode is executed in a cooling operation mode. [Figure 2] FIG. 2 is a block diagram of an example of a vehicle air conditioner. [Figure 3] FIG. 3 is a diagram showing an outline of a configuration example of a vehicle air conditioner, and is a diagram showing an example of a state of the vehicle air conditioner when the storage mode is executed in the heating operation mode. [Figure 4] FIG. 4 is a diagram illustrating an example of a flowchart showing a processing procedure when the storage mode is executed. [Figure 5] FIG. 5 is a diagram showing an example of a flowchart illustrating a processing procedure when the stored refrigerant is released. [Figure 6] FIG. 6 is a diagram showing an example of a flowchart illustrating a processing procedure when the stored refrigerant is released. [Figure 7] FIG. 7 is a diagram showing an example of a flowchart illustrating a processing procedure when the stored refrigerant is released. DETAILED DESCRIPTION OF THE INVENTION

[0008] [Configuration of vehicle air conditioning system]

[0009] FIG. 1 is an explanatory diagram showing an outline of a configuration example of a vehicle air conditioner 1 according to this embodiment.

[0010] 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.

[0011] The vehicle air conditioner 1 also includes an HVAC (Heating, Ventilation, and Air Conditioning) unit 100 as an air conditioning unit. The operation of the vehicle air conditioner 1 is controlled by a control device 200 (see FIG. 2) based on the detected values ​​of various sensors, various requests, etc.

[0012] <Refrigerant circuit> The refrigerant circuit 10 includes a compressor 11 that compresses gaseous refrigerant to a high temperature and high pressure and then discharges it, an interior condenser 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 reducing devices 13a, 13b, and 13c 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, an evaporator 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 an exterior heat exchanger 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.

[0013] In the low-temperature side heat exchanger 14, the refrigerant exchanges heat with a 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.

[0014] The elements of the refrigerant circuit 10 are connected by refrigerant flow paths 10a, 10b, 10c, 10e, 10f, 10g, 10h, 10i, 10j, 10k, 10m, 10n, 10p, and 10q.

[0015] A discharge side 11a of the compressor 11 is connected to an inlet side 12a of an indoor condenser 12 via a refrigerant flow path 10a connected thereto.

[0016] An outlet side 12b of the indoor condenser 12 is connected to an inlet side 17a of the outdoor heat exchanger 17 via a refrigerant flow path 10b connected thereto, a branch point 18a, and a downstream refrigerant flow path 10c. A pressure reducing device 13a is installed on the path of the refrigerant flow path 10c.

[0017] An outlet side 17b of the outdoor heat exchanger 17 is connected to an inlet side 16a of the evaporator 16 via a refrigerant flow path 10d connected thereto, a branch point 18b, a refrigerant flow path 10e, a branch point 18c, a refrigerant flow path 10f, a branch point 18d, and a downstream refrigerant flow path 10g. A flow path opening / closing valve 20a is provided on the path of the refrigerant flow path 10e. A pressure reducing device 13b is provided on the path of the refrigerant flow path 10g.

[0018] The outlet side 12b of the indoor condenser 12 is connected to the inlet side 16a of the evaporator 16 via the refrigerant flow path 10b, branch point 18a, refrigerant flow path 10h, branch point 18c, refrigerant flow path 10f, branch point 18d, and the downstream refrigerant flow path 10g. A flow path opening / closing valve 20b is provided on the path of the refrigerant flow path 10h.

[0019] An outlet side 16b of the evaporator 16 is connected to an inlet side 15a of the accumulator 15 via a refrigerant flow path 10i connected thereto, a junction 19a, a refrigerant flow path 10j, a junction 19b, and a downstream refrigerant flow path 10k. A flow path opening / closing valve 20c is provided on the refrigerant flow path 10i. A check valve 21a is provided on the refrigerant flow path 10j to prevent the refrigerant from flowing back into the evaporator 16.

[0020] Outlet side 17b of outdoor heat exchanger 17 is connected to the inlet of refrigerant passage 14a of low-temperature side heat exchanger 14 via refrigerant flow path 10d, branch point 18b, refrigerant flow path 10e, branch point 18c, refrigerant flow path 10f, branch point 18d, and downstream refrigerant flow path 10m. Pressure reducing device 13c is installed on the path of refrigerant flow path 10m.

[0021] 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 10n connected thereto, a junction 19b, and a refrigerant passage 10k downstream thereof. A passage opening / closing valve 20d is installed on the path of the refrigerant passage 10n.

[0022] An outlet side 17b of the outdoor heat exchanger 17 is connected to an inlet side 15a of the accumulator 15 via a refrigerant flow path 10d connected thereto, a branch point 18b, a refrigerant flow path 10p, a junction 19a, a refrigerant flow path 10j, the junction 19b, and a downstream refrigerant flow path 10k. A flow path opening / closing valve 20e is provided on the path of the refrigerant flow path 10n.

[0023] An outlet side 15b of the accumulator 15 is connected to a suction side 11b of the compressor 11 via a refrigerant flow path 10q connected thereto. A low-pressure side refrigerant temperature sensor 230a (see FIG. 2) and a low-pressure side refrigerant pressure sensor 240a (see FIG. 2) are installed in the refrigerant flow path 10n.

[0024] <Battery temperature control circuit> The battery temperature control circuit 40, which serves 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 a temperature control target. 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.

[0025] 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.

[0026] 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.

[0027] On the path of the heat medium flow path 40b, a circulation pump P40 and a heat medium heater 42 serving as heating means 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.

[0028] <HVAC unit> The indoor condenser 12 and evaporator 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. The air flow passage 120 is an air flow passage for air that exchanges heat in the indoor condenser 12 and the evaporator 16.

[0029] The HVAC unit 100 also has an intake unit 130 as an inside / outside air switching device. The intake unit 130 can switch the air introduced into the case 110 between outside air (outside air introduction) and inside air (inside air circulation) by closing either an outside air intake port that introduces outside air or an inside air intake port that introduces inside air. The intake unit 130 can also adjust the ratio of the air introduced into the inside of the vehicle cabin and the air introduced into the case 110 by closing either the outside air intake port or the inside air intake port to switch between outside air introduction and inside air circulation, or by adjusting the ratio of outside air introduction and inside air circulation to an arbitrary ratio and introducing air into the case 110. 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. The blower 140 blows air into the vehicle interior for heat exchange in the interior condenser 12 and the evaporator 16 .

[0030] An evaporator 16 is installed upstream of the air flow passage 120. An interior condenser passage 121 and a bypass passage 122 are formed in parallel downstream of the air flow passage 120. The interior condenser 12 is provided in the interior condenser passage 121. Therefore, when air introduced into the case 110 is guided to the interior condenser passage 121, the air is ventilated to the evaporator 16 and then to the interior condenser 12. On the other hand, when air introduced into the case 110 is guided to the bypass passage 122, the air is ventilated to the evaporator 16 and then bypasses the interior condenser 12. The ratio of air passing through the interior condenser passage 121 to air passing through the bypass passage 122 is adjusted by an air mix damper 150.

[0031] Control Device FIG. 2 is an explanatory diagram showing an outline of a configuration example of the control device 200 provided in the vehicle air conditioner 1 according to this embodiment.

[0032] The control device 200 includes a processor 201, a memory 202, a storage 203, and an interface 204. The processor 201 is, for example, a central processing unit (CPU) or a micro-processing unit (MPU). The memory 202 is, for example, a random access memory (RAM). The storage 203 is a rewritable non-volatile memory such as a hard disk drive (HDD), a solid state drive (SSD), or a flash memory. The storage 203 stores system programs including an operating system (OS) and control programs including computer-readable code required for control calculations. The processor 201 reads the system programs and control programs, expands them into the memory 202, and executes them to perform various processes. The interface 204 controls communication between the control device 200 and the components of the vehicle air conditioner 1.

[0033] Detection information is input from various sensors to the control device 200. For example, detection information is input to the control device 200 from a blown air temperature sensor 210 that detects the temperature of air blown into the vehicle cabin, an outside air temperature sensor 220 that detects the outside air temperature, a refrigerant temperature sensor 230 that detects the temperature of the refrigerant circulating through the refrigerant circuit 10, a refrigerant pressure sensor 240 that detects the pressure of the refrigerant circulating through the refrigerant circuit 10, a vehicle interior temperature sensor 250 that detects the temperature inside the vehicle cabin, a rotation speed detection sensor 260 that detects the rotation speed of the compressor 11, and PT sensors 270a, 270b, and 270c that detect the pressure and temperature at the installation locations.

[0034] The refrigerant temperature sensor 230 is composed of multiple sensors that detect the refrigerant temperature at various locations in the refrigerant circuit 10, and includes a low-pressure-side refrigerant temperature sensor 230a that detects the temperature of the refrigerant on the low-pressure side of the refrigerant circuit 10 and a high-pressure-side refrigerant temperature sensor 230b that detects the temperature of the refrigerant on the high-pressure side of the refrigerant circuit 10. The low-pressure-side refrigerant temperature sensor 230a is installed, for example, on the suction side 11b of the compressor 11. The high-pressure-side refrigerant temperature sensor 230b is installed, for example, on the outlet side 12b of the indoor condenser 12.

[0035] The refrigerant pressure sensor 240 is composed of multiple sensors that detect the refrigerant pressure at various locations in the refrigerant circuit 10, and includes a low-pressure side refrigerant pressure sensor 240a that detects the pressure of the refrigerant on the low-pressure side of the refrigerant circuit 10 and a high-pressure side refrigerant pressure sensor 240b that detects the pressure of the refrigerant on the high-pressure side of the refrigerant circuit 10. The low-pressure side refrigerant pressure sensor 240a is installed, for example, on the suction side 11b of the compressor 11. The high-pressure side refrigerant pressure sensor 240b is installed, for example, on the outlet side 12b of the indoor condenser 12.

[0036] 1 is the pressure of the refrigerant in the path from the discharge side 11a of the compressor 11 to the pressure reducing devices 13a, 13b, and 13c. In other words, the pressure of the high-pressure side of the refrigerant circuit 10 is the pressure of the refrigerant on the discharge side 11a of the compressor 11.

[0037] 1 is the pressure of the refrigerant in the path from the pressure reducing devices 13a, 13b, and 13c to the suction side 11b of the compressor 11. In other words, the pressure on the low pressure side of the refrigerant circuit 10 is the pressure of the refrigerant on the suction side 11b of the compressor 11.

[0038] The PT sensor 270a is provided in the refrigerant flow path 10d connected to the outlet side 17b of the outdoor heat exchanger 17. The PT sensor 270a is used to calculate the degree of subcooling SC of the refrigerant during cooling operation.

[0039] The PT sensor 270b is provided in the refrigerant flow path 10b connected to the outlet side 12b of the indoor condenser 12. The PT sensor 270b is used to calculate the degree of subcooling SC of the refrigerant during heating operation. In addition, the pressure and temperature detected by the PT sensor 270b are compared with test values ​​to determine whether to release the stored refrigerant (see FIG. 7).

[0040] The PT sensor 270c is provided in the refrigerant flow path 10p connected to the outlet side 15b of the accumulator 15. The PT sensor 270c is used to calculate the degree of superheat SH of the refrigerant during cooling operation. The degree of superheat SH is calculated based on the pressure and temperature detected by the PT sensor 270c, and a determination is made as to whether to release the stored refrigerant (see FIG. 5). The pressure detected by the PT sensor 270c is compared with a set value, and a determination is made as to whether to release the stored refrigerant (see FIG. 6).

[0041] The control device 200 selects a path in the refrigerant circuit 10 by opening and closing the pressure reducing devices 13a, 13b, and 13c and the flow path opening and closing valves 20a, 20b, 20c, 20d, and 20e 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, the heat medium heater 42, and the pressure reducing devices 13a, 13b, and 13c to control the amount of heat released from the refrigerant.

[0042] [Operation of vehicle air conditioning system] A specific operation of the vehicle air conditioner 1 according to this embodiment will be described.

[0043] <Cooling operation mode> 1 shows the state of the vehicle air conditioner 1 when the outside temperature is high. At this time, the interior of the vehicle is cooled by executing the cooling operation mode.

[0044] In the cooling operation mode, the control device 200 opens the pressure reducing devices 13a and 13b, opens the flow path opening / closing valves 20a, 20c, and 20d, and fully closes the pressure reducing device 13c and the flow path opening / closing valves 20b and 20e.

[0045] As a result, the refrigerant discharged from the compressor 11 flows into the refrigerant flow path 10a and passes through the indoor condenser 12. The refrigerant that has passed through the indoor condenser 12 flows into the refrigerant flow paths 10b and 10c and passes through the outdoor heat exchanger 17. The refrigerant that has dissipated heat while passing through the outdoor heat exchanger 17 flows into the refrigerant flow paths 10d, 10e, 10f, and 10g and passes through the evaporator 16. The refrigerant that has passed through the evaporator 16 flows into the refrigerant flow paths 10i, 10j, and 10k and then into the accumulator 15. The refrigerant that has flowed into the accumulator 15 flows into the refrigerant flow path 10q and then into the compressor 11.

[0046] That is, refrigerant flow paths 10a, 10b, 10c, 10d, 10e, 10f, 10g, 10i, 10j, 10k, and 10q form a circulation path in which the refrigerant that has passed through compressor 11 passes through evaporator 16. As a result, the refrigerant that has been reduced to a low temperature and pressure by pressure reducing device 13b passes through evaporator 16, and the interior of the vehicle is cooled by the air cooled by evaporator 16. At this time, air mix damper 150 closes interior condenser passage 121, so the interior of the vehicle is not heated, and the air cooled by evaporator 16 passes through bypass passage 122 to cool the interior of the vehicle.

[0047] As described above, in the cooling operation mode, the refrigerant flow path is selected as described above, and therefore heat exchange is not performed in the low-temperature side heat exchanger 14. Note that Fig. 1 shows a state in which the cooling operation mode refrigerant storage mode is being performed, as will be described later. Therefore, the figure shows a state in which the refrigerant is flowing into the refrigerant flow paths 10m and 10n.

[0048] <Heating operation mode> 3 shows the state of the vehicle air conditioner 1 when the outside temperature is low. At this time, the vehicle interior is heated by executing the heating operation mode.

[0049] In the heating operation mode, the control device 200 opens the pressure reducing device 13c and the flow path opening / closing valves 20b, 20d, and 20e, and also fully closes the pressure reducing devices 13a and 13b and the flow path opening / closing valves 20a and 20c.

[0050] As a result, the refrigerant discharged from the compressor 11 flows into refrigerant flow path 10a and passes through the indoor condenser 12. The refrigerant that has passed through the indoor condenser 12 flows into refrigerant flow paths 10b, 10h, 10f, and 10m and passes through refrigerant passage 14a of the low-temperature side heat exchanger 14. The refrigerant is warmed by the exhaust heat of the battery 41 as it passes through refrigerant passage 14a of the low-temperature side heat exchanger 14 and then flows into refrigerant flow paths 10n and 10k and into the accumulator 15. The refrigerant that has flowed into the accumulator 15 flows into refrigerant flow path 10q and into the compressor 11.

[0051] That is, refrigerant flow paths 10a, 10b, 10c, 10d, 10e, 10f, 10g, 10i, 10j, 10m, 10n, 10k, and 10q form a circulation path in which the refrigerant that has passed through compressor 11 passes through interior condenser 12. As a result, the refrigerant that has been heated to a high temperature and pressure by compressor 11 passes through interior condenser 12, and the interior of the vehicle is heated by the air heated by interior condenser 12. At this time, air mix damper 150 opens interior condenser passage 121, so that the air heated by interior condenser 12 passes through interior condenser passage 121 and the interior of the vehicle is heated.

[0052] As described above, in the heating operation mode, the refrigerant flow path is selected as described above, and therefore heat exchange is not performed in the outdoor heat exchanger 17. Note that Fig. 3 shows a state in which the refrigerant storage mode is being performed when the heating operation mode is being performed, as will be described later. Therefore, the figure shows a state in which the refrigerant flows into the refrigerant flow paths 10c, 10d, and 10p.

[0053] <Storage mode> When the vehicle air conditioner 1 executes an air conditioning operation mode, excess refrigerant may occur in the executed operation mode. Therefore, the control device 200 can execute a storage mode to store the excess refrigerant when executing an operation mode. Figure 4 shows a specific example of processing when executing the storage mode.

[0054] As shown in FIG. 4, when an operation mode is designated, the control device 200 starts the execution of the designated operation mode (S1).

[0055] Next, the control device 200 identifies heat exchangers that will not actively perform heat exchange in the refrigerant circuit 10 when the specified operation mode is executed (S2). The control device 200 identifies heat exchangers that will not actively perform heat exchange based on the circuit configuration in each operation mode.

[0056] At this time, in the cooling operation mode, the low-temperature side heat exchanger 14 is identified as a heat exchanger that does not actively perform heat exchange (see FIG. 1), and in the heating operation mode, the outdoor heat exchanger 17 is identified as a heat exchanger that does not actively perform heat exchange (see FIG. 3).

[0057] The control device 200 then sets a heat exchanger that does not actively perform heat exchange as a storage unit that stores excess refrigerant generated in the refrigerant circuit 10. That is, in the cooling operation mode, the low-temperature side heat exchanger 14 is set as the storage unit, and in the heating operation mode, the outdoor heat exchanger 17 is set as the storage unit.

[0058] Next, the control device 200 determines whether the compressor 11 is in the liquid discharge mode (S3). The liquid discharge mode is a mode that prevents breakdown of the compressor 11 due to the compressor 11 performing liquid compression. In other words, if the compressor 11 performs liquid compression, there is a possibility that the compression mechanism inside the compressor 11 will be damaged, and this is an operation mode of the compressor 11 that prevents this.

[0059] Then, if the liquid discharge mode of the compressor 11 is being executed (S3: Yes), the control device 200 proceeds to step S6. That is, since the liquid discharge mode of the compressor 11 is being executed due to an excessive amount of refrigerant circulating, if the liquid discharge mode of the compressor 11 is being executed, the control device 200 proceeds to step S6 and stores the excess refrigerant to bring the amount of refrigerant circulating within an appropriate range. On the other hand, if the liquid discharge mode of the compressor 11 is not being executed (S3: No), the control device 200 calculates the degree of subcooling SC (S4).

[0060] In the cooling operation mode, the degree of subcooling SC is calculated based on the pressure and temperature detected by the PT sensor 270a installed in the refrigerant flow path 10d. For example, in the cooling operation mode, the saturation temperature is determined based on the pressure at the outlet side 17b of the outdoor heat exchanger 17 detected by the PT sensor 270a, and the degree of subcooling SC is calculated by subtracting the temperature at the outlet side 17b of the outdoor heat exchanger 17 detected by the PT sensor 270a from the saturation temperature. The control device 200 stores a data table that associates the pressure at the outlet side 17b of the outdoor heat exchanger 17 with the saturation temperature based on data from a pH diagram. By searching this data table, the saturation temperature can be determined from the pressure at the outlet side 17b of the outdoor heat exchanger 17. Note that the saturation temperature may also be calculated using a formula based on data from the pH diagram.

[0061] In addition, in the heating operation mode, the degree of subcooling SC is calculated based on the pressure and temperature detected by the PT sensor 270b installed in the refrigerant flow path 10b. For example, in the heating operation mode, the saturation temperature is determined based on the pressure at the outlet side 12b of the indoor condenser 12 detected by the PT sensor 270b, and the degree of subcooling SC is calculated by subtracting the temperature at the outlet side 12b of the indoor condenser 12 detected by the PT sensor 270b from the saturation temperature. The control device 200 stores a data table that associates the pressure at the outlet side 12b of the indoor condenser 12 with the saturation temperature based on data from a pH diagram. By searching this data table, the saturation temperature can be determined from the pressure at the outlet side 12b of the indoor condenser 12. Note that the saturation temperature may also be calculated using a formula based on data from the pH diagram.

[0062] Next, the control device 200 determines whether the degree of supercooling SC is equal to or greater than a specified value (S5). For example, it determines whether the degree of supercooling SC is equal to or greater than approximately 35K.

[0063] Next, if the degree of supercooling SC is equal to or greater than the specified value (S5: Yes), the control device 200 closes the valve device downstream of the heat exchanger serving as the storage section (S6).

[0064] At this time, in the cooling operation mode, the flow path opening / closing valve 20d arranged downstream of the low-temperature side heat exchanger 14 serving as a storage part is fully closed. Also, in the heating operation mode, the flow path opening / closing valve 20e arranged downstream of the outdoor heat exchanger 17 serving as a storage part is fully closed.

[0065] Next, the control device 200 opens the valve device upstream of the heat exchanger serving as the storage unit (S7), thereby starting the storage mode and starting the storage of the refrigerant in the heat exchanger that does not actively perform heat exchange.

[0066] At this time, in the cooling operation mode, the pressure reducing device 13c, which is disposed upstream of the low-temperature side heat exchanger 14 serving as a storage section, is opened. As a result, in the cooling operation mode, the storage mode is started by fully closing the flow path opening / closing valve 20d and opening the pressure reducing device 13c. As a result, the refrigerant that has flowed into the refrigerant flow path 10n can be blocked by the flow path opening / closing valve 20d, and the refrigerant can be stored in the low-temperature side heat exchanger 14 (see FIG. 1).

[0067] In addition, in the heating operation mode, the pressure reducing device 13a, which is arranged upstream of the outdoor heat exchanger 17 serving as a storage unit, is opened. As a result, in the heating operation mode, the storage mode is started by fully closing the flow path opening / closing valve 20e and opening the pressure reducing device 13a. As a result, the refrigerant that has flowed into the refrigerant flow path 10d can be blocked by the flow path opening / closing valve 20e, and the refrigerant can be stored in the outdoor heat exchanger 17 (see FIG. 3).

[0068] After the process of step S7, the control device 200 returns to the process of step S5. On the other hand, if the degree of subcooling SC is less than the specified value (S5: No), the control device 200 closes the valve device upstream of the heat exchanger used as the storage unit (S8). This ends the execution of the storage mode, and the storage of the refrigerant in the heat exchanger used as the storage unit ends.

[0069] At this time, in the cooling operation mode, the pressure reducing device 13c, which is disposed upstream of the low-temperature side heat exchanger 14 serving as a storage section, is fully closed, thereby ending the storage mode and terminating the storage of the refrigerant in the low-temperature side heat exchanger 14.

[0070] In addition, in the heating operation mode, the pressure reducing device 13a, which is disposed upstream of the outdoor heat exchanger 17 serving as a storage unit, is fully closed, thereby ending the storage mode and terminating the storage of the refrigerant in the outdoor heat exchanger 17.

[0071] In this embodiment, in the cooling operation mode, the subcooling degree SC is calculated using the PT sensor 270a installed on the outlet side 17b of the outdoor heat exchanger 17, and in the heating operation mode, the subcooling degree SC is calculated using the PT sensor 270b installed on the outlet side 12b of the indoor condenser 12. However, the subcooling degree SC may also be calculated based on the detection results of a sensor other than the PT sensor 270a or the PT sensor 270b.

[0072] In this embodiment, an example is given in which the valve device upstream of the heat exchanger used as the storage section is closed when the degree of subcooling SC is less than a specified value, but the conditions for closing the valve device upstream of the heat exchanger used as the storage section may be different from those in this embodiment, for example, by closing the valve device after a certain period of time has elapsed.

[0073] In this embodiment, the flow path opening / closing valve 20d and the flow path opening / closing valve 20e are given as examples of valve devices downstream of the heat exchanger serving as a storage section, but the valve device downstream of the heat exchanger serving as a storage section does not have to be limited to a flow path opening / closing valve, and may instead be a pressure reducing device.

[0074] In this embodiment, pressure reducing device 13a and pressure reducing device 13c are given as examples of valve devices upstream of the heat exchanger used as the storage section, but the valve device upstream of the heat exchanger used as the storage section does not have to be limited to a pressure reducing device, and may be a flow path opening / closing valve.

[0075] [Controlling the release of stored refrigerant] Due to the influence of the refrigerant stored in the heat exchanger serving as a storage unit, the amount of refrigerant circulating through the refrigerant circuit 10 may be insufficient when the refrigerant circuit 10 is operating stably (under low load), depending on the operating state of the vehicle air conditioner 1. Therefore, it is preferable to add the stored refrigerant as refrigerant circulating through the refrigerant circuit 10 depending on the operating state of the vehicle air conditioner 1. Therefore, the vehicle air conditioner 1 of this embodiment executes control to release the stored refrigerant when a refrigerant shortage is detected after the storage mode has ended. A specific example of control to release the stored refrigerant when a refrigerant shortage is detected will be described below with reference to FIGS. 5 to 7.

[0076] <Control based on superheat degree SH> 5, the control device 200 acquires, as refrigerant information, the pressure and temperature detected by the PT sensor 270c, i.e., the pressure and temperature on the suction side of the compressor 11 (S11). The pressure and temperature detected by the PT sensor 270c, i.e., the pressure and temperature on the suction side of the compressor 11, can be rephrased as the pressure and temperature on the low-pressure side of the refrigerant circuit 10.

[0077] Next, the control device 200 calculates the degree of superheat SH based on the refrigerant information acquired in step S11 (S12).

[0078] For example, the saturation temperature is determined based on the pressure detected by the PT sensor 270c, i.e., the pressure on the suction side of the compressor 11, and the degree of superheat SH is calculated by subtracting the saturation temperature from the temperature detected by the PT sensor 270c, i.e., the temperature on the suction side of the compressor 11. The control device 200 holds a data table that associates the pressure on the suction side of the compressor 11 with the saturation temperature based on data from a pH diagram, and can determine the saturation temperature from the pressure on the suction side of the compressor 11 by searching the data table. Note that the saturation temperature may also be calculated using a formula based on data from the pH diagram.

[0079] Next, the control device 200 determines whether the degree of superheat SH is equal to or greater than a predetermined value (e.g., 1) (S13). When the control device 200 determines that the degree of superheat SH is not equal to or greater than a predetermined value (e.g., 1) (S13: No), the process returns to step S11.

[0080] On the other hand, when the control device 200 determines that the superheat degree SH is equal to or greater than an arbitrarily set value (for example, 1) (S13: Yes), it opens the valve device downstream of the heat exchanger used as the storage section and returns to step S11 (S14).

[0081] At this time, in the cooling operation mode, the flow path opening / closing valve 20d arranged downstream of the low-temperature side heat exchanger 14 serving as a storage unit is opened, and in the heating operation mode, the flow path opening / closing valve 20e arranged downstream of the outdoor heat exchanger 17 serving as a storage unit is opened.

[0082] The opening time of the valve device may be set appropriately, for example, to a time calculated based on the degree of superheat SH or to a fixed time.

[0083] As described above, by opening the valve device downstream of the heat exchanger serving as the storage unit, it is possible to add the refrigerant to make up for the shortage, and the amount of refrigerant circulating in the refrigerant circuit 10 can be maintained at an appropriate level, thereby preventing malfunctions such as seizure of the compressor 11 due to an insufficient amount of refrigerant circulating. Furthermore, because the amount of refrigerant circulating can be maintained at an appropriate level, it is possible to prevent the accumulator 15 from becoming larger even if the refrigerant circuit 10 becomes more complex.

[0084] <Control Based on the Pressure on the Suction Side of the Compressor 11> 6, the control device 200 acquires, as refrigerant information, the pressure detected by the PT sensor 270c, i.e., the pressure on the suction side of the compressor 11 (S21). The pressure detected by the PT sensor 270c, i.e., the pressure on the suction side of the compressor 11, can be rephrased as the pressure on the low-pressure side of the refrigerant circuit 10.

[0085] Next, the control device 200 determines whether the acquired pressure on the suction side of the compressor 11 is lower than the set value (S22). When the control device 200 determines that the acquired pressure on the suction side of the compressor 11 is higher than the set value (S22: No), the process returns to step S21.

[0086] On the other hand, when the control device 200 determines that the acquired pressure on the suction side of the compressor 11 is lower than the set value (S22: Yes), it opens the valve device downstream of the heat exchanger used as the storage section and returns to step S21 (S23).

[0087] At this time, in the cooling operation mode, the flow path opening / closing valve 20d arranged downstream of the low-temperature side heat exchanger 14 serving as a storage unit is opened, and in the heating operation mode, the flow path opening / closing valve 20e arranged downstream of the outdoor heat exchanger 17 serving as a storage unit is opened.

[0088] The opening time of the valve device may be set appropriately, for example, to a time calculated based on the pressure on the suction side of the compressor 11 or to a fixed time.

[0089] As described above, by opening the valve device downstream of the heat exchanger serving as the storage unit, it is possible to add the refrigerant to make up for the shortage, and the amount of refrigerant circulating in the refrigerant circuit 10 can be maintained at an appropriate level, thereby preventing malfunctions such as seizure of the compressor 11 due to an insufficient amount of refrigerant circulating. Furthermore, because the amount of refrigerant circulating can be maintained at an appropriate level, it is possible to prevent the accumulator 15 from becoming larger even if the refrigerant circuit 10 becomes more complex.

[0090] <Control Based on Pressure and Temperature on the Discharge Side of the Compressor 11> 7, the control device 200 acquires, as refrigerant information, the pressure and temperature detected by the PT sensor 270b, i.e., the pressure and temperature on the discharge side of the compressor 11 (S31). The pressure and temperature detected by the PT sensor 270c, i.e., the pressure and temperature on the discharge side of the compressor 11, can be rephrased as the pressure and temperature on the high-pressure side of the refrigerant circuit 10.

[0091] Next, the control device 200 compares the acquired pressure and temperature on the discharge side of the compressor 11 with test values ​​measured in advance (S32). The test values ​​are data indicating the correlation between the pressure on the discharge side of the compressor 11 and the temperature on the discharge side of the compressor 11. The control device 200 stores the test values ​​in advance and can identify an appropriate temperature on the discharge side of the compressor 11 according to the pressure on the discharge side of the compressor 11.

[0092] Next, the control device 200 determines whether the acquired temperature on the discharge side of the compressor 11 is higher than the appropriate temperature indicated by the test value (S33). When the control device 200 determines that the acquired temperature on the discharge side of the compressor 11 is lower than the appropriate temperature indicated by the test value (S33: No), the process returns to step S31.

[0093] On the other hand, when the control device 200 determines that the acquired temperature on the discharge side of the compressor 11 is higher than the appropriate temperature indicated by the test value (S33: Yes), it opens the valve device downstream of the heat exchanger used as the storage section and returns to step S31 (S34).

[0094] At this time, in the cooling operation mode, the flow path opening / closing valve 20d arranged downstream of the low-temperature side heat exchanger 14 serving as a storage unit is opened, and in the heating operation mode, the flow path opening / closing valve 20e arranged downstream of the outdoor heat exchanger 17 serving as a storage unit is opened.

[0095] The opening time of the valve device may be set appropriately, for example, to a time calculated based on the temperature on the discharge side of the compressor 11 or to a fixed time.

[0096] As described above, by opening the valve device downstream of the heat exchanger serving as the storage unit, it is possible to add the refrigerant to make up for the shortage, and the amount of refrigerant circulating in the refrigerant circuit 10 can be maintained at an appropriate level, thereby preventing malfunctions such as seizure of the compressor 11 due to an insufficient amount of refrigerant circulating. Furthermore, because the amount of refrigerant circulating can be maintained at an appropriate level, it is possible to prevent the accumulator 15 from becoming larger even if the refrigerant circuit 10 becomes more complex.

[0097] [Effects of this embodiment] (1) a refrigerant circuit 10 having a low-temperature side heat exchanger 14 and an outdoor heat exchanger 17 as a plurality of heat exchangers; A vehicle air conditioner (1) including flow path opening / closing valves (20d, 20e) and pressure reducing devices (13a, 13c) as valve devices arranged upstream and downstream of a low-temperature side heat exchanger (14) and an exterior heat exchanger (17), The low-temperature side heat exchanger 14 or the outdoor heat exchanger 17, which does not actively perform heat exchange, is used as a storage section for storing excess refrigerant generated in the refrigerant circuit 10, A storage mode is provided in which excess refrigerant in the air conditioning operation mode is stored in the storage section, If a shortage of refrigerant in the refrigerant circuit 10 is detected after the storage mode has been completed, the flow path opening / closing valve 20d downstream of the low-temperature side heat exchanger 14 used as the storage section or the flow path opening / closing valve 20e downstream of the outdoor heat exchanger 17 used as the storage section is opened. Therefore, the amount of refrigerant circulating in the refrigerant circuit 10 can be kept appropriate, preventing malfunctions such as seizure of the compressor 11 due to an insufficient amount of refrigerant circulating. Furthermore, because the amount of refrigerant circulating can be kept appropriate, the accumulator 15 can be prevented from becoming larger even if the refrigerant circuit 10 becomes more complex.

[0098] (2) The flow path opening / closing valve 20d or the flow path opening / closing valve 20e downstream of the low-temperature side heat exchanger 14 or the outdoor heat exchanger 17 serving as the storage section is closed at the start of execution of the storage mode, and the pressure reducing device 13a or the pressure reducing device 13c upstream of the low-temperature side heat exchanger 14 or the outdoor heat exchanger 17 serving as the storage section is closed at the end of execution of the storage mode. Therefore, by preventing excess refrigerant from flowing out from the low-temperature side heat exchanger 14 or the exterior heat exchanger 17 when the storage mode ends, the amount of refrigerant circulating can be maintained at an appropriate amount.

[0099] (3) The PT sensor 270c is provided as an intake side sensor for detecting the pressure and temperature of the refrigerant on the intake side of the compressor 11 of the refrigerant circuit 10. Calculating the degree of superheat based on the pressure and temperature of the refrigerant detected by the PT sensor 270c; Determine whether the calculated superheat degree is equal to or greater than a set value; If the calculated degree of superheat is equal to or greater than a set value, a shortage of refrigerant in the refrigerant circuit 10 is detected; If a shortage of refrigerant in the refrigerant circuit 10 is detected after the storage mode has been completed, the flow path opening / closing valve 20d downstream of the low-temperature side heat exchanger 14 used as the storage section or the flow path opening / closing valve 20e downstream of the outdoor heat exchanger 17 used as the storage section is opened. Therefore, the amount of refrigerant circulating in the refrigerant circuit 10 can be kept appropriate, preventing malfunctions such as seizure of the compressor 11 due to an insufficient amount of refrigerant circulating. Furthermore, because the amount of refrigerant circulating can be kept appropriate, the accumulator 15 can be prevented from becoming larger even if the refrigerant circuit 10 becomes more complex.

[0100] (4) The PT sensor 270c is provided as an intake side sensor that detects the pressure of the refrigerant on the intake side of the compressor 11 of the refrigerant circuit 10. Determine whether the pressure of the refrigerant on the suction side of the compressor 11 detected by the PT sensor 270c is lower than a set value; When the intake side of the compressor 11 is lower than the set value, a shortage of refrigerant in the refrigerant circuit 10 is detected. If a shortage of refrigerant in the refrigerant circuit 10 is detected after the storage mode has been completed, the flow path opening / closing valve 20d downstream of the low-temperature side heat exchanger 14 used as the storage section or the flow path opening / closing valve 20e downstream of the outdoor heat exchanger 17 used as the storage section is opened. Therefore, the amount of refrigerant circulating in the refrigerant circuit 10 can be kept appropriate, preventing malfunctions such as seizure of the compressor 11 due to an insufficient amount of refrigerant circulating. Furthermore, because the amount of refrigerant circulating can be kept appropriate, the accumulator 15 can be prevented from becoming larger even if the refrigerant circuit 10 becomes more complex.

[0101] (5) The PT sensor 270b is provided as a discharge-side sensor that detects the pressure and temperature of the refrigerant on the discharge side of the compressor 11 of the refrigerant circuit 10. determining whether the temperature of the refrigerant on the discharge side of the compressor 11 is higher than a test value based on the pressure and temperature of the refrigerant on the discharge side of the compressor 11 detected by the PT sensor 270b; When the temperature of the refrigerant on the discharge side of the compressor 11 is higher than the test value, a shortage of refrigerant in the refrigerant circuit 10 is detected. If a shortage of refrigerant in the refrigerant circuit 10 is detected after the storage mode has been completed, the flow path opening / closing valve 20d downstream of the low-temperature side heat exchanger 14 used as the storage section or the flow path opening / closing valve 20e downstream of the outdoor heat exchanger 17 used as the storage section is opened. Therefore, the amount of refrigerant circulating in the refrigerant circuit 10 can be kept appropriate, preventing malfunctions such as seizure of the compressor 11 due to an insufficient amount of refrigerant circulating. Furthermore, because the amount of refrigerant circulating can be kept appropriate, the accumulator 15 can be prevented from becoming larger even if the refrigerant circuit 10 becomes more complex.

[0102] 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. [Explanation of symbols]

[0103] 1: Vehicle air conditioning system 10: refrigerant circuit, 11: compressor, 12: indoor condenser, 13a, 13b, 13c, 13d: pressure reducing device, 14: low-temperature side heat exchanger, 15: accumulator, 16: evaporator, 17: outdoor heat exchanger 40: Battery temperature control circuit, 41: Battery, 42: Heat medium heating device, P40: Circulation pump 100: HVAC unit, 110: case, 120: air flow passage, 121: indoor condenser passage, 122: bypass passage, 150: air mix damper

Claims

1. a refrigerant circuit having a plurality of heat exchangers; a valve device disposed on the upstream side and downstream side of each of the plurality of heat exchangers, The heat exchanger that does not actively perform heat exchange is used as a storage unit that stores excess refrigerant generated in the refrigerant circuit, A storage mode is provided in which excess refrigerant in the air conditioning operation mode is stored in the storage section, When a shortage of refrigerant in the refrigerant circuit is detected after the execution of the storage mode is completed, the valve device downstream of the heat exchanger used as the storage section is opened.

1. A vehicle air conditioning system comprising:

2. The valve device downstream of the heat exchanger serving as the storage unit is closed at the start of execution of the storage mode, and the valve device upstream of the heat exchanger serving as the storage unit is closed at the end of execution of the storage mode.

2. The air conditioning system for a vehicle according to claim 1.

3. The refrigerant circuit includes a suction side sensor for detecting the pressure and temperature of the refrigerant on the suction side of the compressor. The degree of superheat is calculated based on the pressure and temperature of the refrigerant detected by the suction side sensor. Determine whether the calculated superheat degree is equal to or greater than a set value; If the calculated degree of superheat is equal to or greater than the set value, a shortage of refrigerant in the refrigerant circuit is detected. When a shortage of refrigerant in the refrigerant circuit is detected after the execution of the storage mode is completed, the valve device downstream of the heat exchanger used as the storage section is opened.

3. The air conditioning system for a vehicle according to claim 1 or 2.

4. a suction side sensor that detects the pressure of the refrigerant on the suction side of the compressor of the refrigerant circuit; determining whether the pressure of the refrigerant on the suction side of the compressor detected by the suction side sensor is lower than a set value; If the suction side of the compressor is lower than the set value, a shortage of refrigerant in the refrigerant circuit is detected. When a shortage of refrigerant in the refrigerant circuit is detected after the execution of the storage mode is completed, the valve device downstream of the heat exchanger used as the storage section is opened.

3. The air conditioning system for a vehicle according to claim 1 or 2.

5. A discharge side sensor is provided to detect the pressure and temperature of the refrigerant on the discharge side of the compressor of the refrigerant circuit, determining whether the temperature of the refrigerant on the discharge side of the compressor is higher than a test value based on the pressure and temperature of the refrigerant on the discharge side of the compressor detected by the discharge side sensor; If the temperature of the refrigerant on the discharge side of the compressor is higher than the test value, a shortage of refrigerant in the refrigerant circuit is detected. When a shortage of refrigerant in the refrigerant circuit is detected after the execution of the storage mode is completed, the valve device downstream of the heat exchanger used as the storage section is opened.

3. The air conditioning system for a vehicle according to claim 1 or 2.

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