Vehicle air conditioning device

Abstract

[Problem] To provide a vehicle air conditioning device capable of preventing defects. [Solution] A vehicle air conditioning device 1 comprises: a refrigerant circuit 10 including an accumulator 15 having a heat exchange unit for exchanging heat with an internal refrigerant; a low pressure-side refrigerant pressure sensor 240a serving as a pressure sensor for detecting pressure on a downstream side of the accumulator 15; and a control device 200. The control device 200 has an accumulator failure detection mode for detecting a failure of the heat exchange unit on the basis of the pressure detected by the low pressure-side refrigerant pressure sensor 240a.

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 for use in electric vehicles (EVs) that do not have a combustion-based heat source such as an engine or in vehicles that have a low amount of heat from a combustion-based heat source. Patent documents 1 and 2, for example, disclose techniques for such vehicle air conditioners that incorporate a heat exchanger made of flat tubes in an accumulator.

[0003] Chinese Utility Model No. 218764102 European Patent Application Publication No. 3748269

[0004] SUMMARY OF THE INVENTION An object of the present invention is to provide a vehicle air conditioner capable of detecting malfunctions.

[0005] According to one aspect of the present invention, a vehicle air conditioning system is provided with a refrigerant circuit including an accumulator having a heat exchange section that exchanges heat with the internal refrigerant, a pressure sensor that detects the pressure downstream of the accumulator, and a control device, and the control device has an accumulator failure detection mode that detects a failure in the heat exchange section based on the pressure detected by the pressure sensor.

[0006] SUMMARY OF THE INVENTION An object of the present invention is to provide a vehicle air conditioner capable of detecting malfunctions.

[0007] Fig. 1 is a diagram showing an example of a configuration of a vehicle air conditioner, Fig. 2 is a diagram showing an example of a block diagram of a vehicle air conditioner, and Fig. 3 is a diagram showing an example of a flowchart showing a processing procedure when a plurality of failure detection modes including an accumulator failure detection mode are executed.

[0008] [Configuration of Vehicle Air Conditioner]

[0009] 1 is an explanatory diagram showing an outline of an example configuration of a vehicle air conditioner 1 according to this embodiment. The thermal management system according to this embodiment includes the vehicle air conditioner 1 and a control device 200 (see FIG. 2) described below.

[0010] The vehicle air conditioner 1 includes a refrigerant circuit 10 configured to circulate a refrigerant. In this embodiment, a carbon dioxide refrigerant is used as the refrigerant. However, the refrigerant is not limited to this, and other refrigerants such as hydrofluoroolefins may also be used. The vehicle air conditioner 1 also includes a heat medium circuit (not shown) through which a heat medium circulates.

[0011] The automotive air conditioner 1 also includes an HVAC (Heating, Ventilation, and Air Conditioning) unit 100 as 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.

[0012] 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 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 supplied to the vehicle cabin, and an exterior heat exchanger 17. 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 the heat medium circulating in the heat medium circuit. 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 heat medium circuit passes. An example of the heat medium circuit is a battery temperature control circuit that controls the temperature of a battery.

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

[0015] A discharge side 11a of the compressor 11 is connected to an inlet side 12a of the indoor condenser 12 via a refrigerant flow path 10a connected thereto. A high-pressure side refrigerant temperature sensor 230b (see FIG. 2) and a high-pressure side refrigerant pressure sensor 240b (see FIG. 2) are installed in the refrigerant flow path 10a.

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

[0017] An outlet side 17b of the outdoor heat exchanger 17 is connected to a high-pressure inlet side 15a of the accumulator 15 via a refrigerant flow path 10c connected thereto, a branch point 18a, and a downstream refrigerant flow path 10d. A plurality of flat tubes 15b are provided in the accumulator 15 as a heat exchanger that exchanges heat with the refrigerant inside. The flat tubes 15b are joined to the accumulator 15 by brazing.

[0018] The high-pressure outlet 15c of the accumulator 15 is connected to the inlet of the refrigerant passage 14a of the low-temperature side heat exchanger 14 via a refrigerant passage 10e connected thereto, a branch point 18b, and a downstream refrigerant passage 10f. A pressure reducing device 13b is installed on the refrigerant passage 10f. A check valve 21a is installed on the refrigerant passage 10e to prevent the refrigerant from flowing back into the accumulator 15.

[0019] The outlet of the refrigerant passage 14a of the low-temperature side heat exchanger 14 is connected to the low-pressure inlet side 15d of the accumulator 15 via a refrigerant passage 10g connected thereto, a junction 19a, and a refrigerant passage 10h downstream thereof. A passage opening / closing valve 20a is installed on the path of the refrigerant passage 10g.

[0020] The high-pressure outlet side 15c of the accumulator 15 is connected to the inlet side 16a of the evaporator 16 via a refrigerant flow path 10e connected thereto, a branch point 18b, and a downstream refrigerant flow path 10i. A pressure reducing device 13c is installed on the path of the refrigerant flow path 10i.

[0021] The outlet side 16b of the evaporator 16 is connected to the low-pressure inlet side 15d of the accumulator 15 via the refrigerant flow path 10j connected thereto, the junction 19b, the refrigerant flow path 10k, the junction 19a, and the refrigerant flow path 10h downstream thereof. A flow path opening / closing valve 20b is installed on the path of the refrigerant flow path 10j.

[0022] The outlet side 17b of the outdoor heat exchanger 17 is connected to the low-pressure inlet side 15d of the accumulator 15 via a refrigerant flow path 10c connected thereto, a branch point 18a, a refrigerant flow path 10m, a junction 19b, a refrigerant flow path 10k, a junction 19a, and a downstream refrigerant flow path 10h. A flow path opening / closing valve 20c is provided on the refrigerant flow path 10m. A check valve 21b is provided on the refrigerant flow path 10k to prevent backflow of refrigerant to the outdoor heat exchanger 17.

[0023] The low-pressure outlet side 15e of the accumulator 15 is connected to the suction side 11b of the compressor 11 via a refrigerant flow path 10n 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] <HVAC Unit> The indoor condenser 12 and the 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.

[0025] The HVAC unit 100 also includes 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 for introducing outside air or an inside air intake port for introducing inside air. The intake unit 130 can also adjust the ratio of inside air and outside 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 includes 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 .

[0026] 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.

[0027] 2 is an explanatory diagram showing an outline of a configuration example of the control device 200 of the vehicle air conditioner 1 according to this embodiment. The thermal management system of this embodiment includes the control device 200 and a heat medium heating device

[0028] 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 microprocessing unit (MPU). The memory 202 is, for example, a random access memory (RAM). The storage 203 is a rewritable nonvolatile 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 components of the vehicle air conditioner 1.

[0029] Detection information from various sensors is input 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, and a rotation speed detection sensor 260 that detects the rotation speed of the compressor 11.

[0030] The refrigerant temperature sensor 230 and the refrigerant pressure sensor 240 are capable of detecting the temperature and pressure of each part of the refrigerant circuit 10, such as the temperature and pressure on the low-pressure side and the temperature and pressure on the high-pressure side.

[0031] The refrigerant temperature sensor 230 is composed of multiple sensors that detect the refrigerant temperature at various points 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.

[0032] The refrigerant pressure sensor 240 is composed of multiple sensors that detect the refrigerant pressure at various points 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.

[0033] 1 is the pressure of the refrigerant in the path from the discharge side 11a of the compressor 11 to the pressure reducing device 13b and the pressure reducing device 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.

[0034] 1 is the pressure of the refrigerant in the path from the pressure reducing device 13b and the pressure reducing device 13c to the suction side 11b of the compressor 11. In other words, the pressure of the low pressure side of the refrigerant circuit 10 is the pressure of the refrigerant on the suction side 11b of the compressor 11.

[0035] The control device 200 selects a path in the refrigerant circuit 10 by opening and closing the pressure reducing devices 13a to 13c and the flow path opening and closing valves 20a, 20b, and 20c 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 heating device 42, and the pressure reducing devices 13a to 13c to control the amount of heat released from the refrigerant.

[0036] [Operation of Vehicle Air Conditioner] A specific operation of the vehicle air conditioner 1 according to this embodiment will be described.

[0037] 1 shows the state of the vehicle air conditioner 1 when the outside temperature is high. At this time, the vehicle interior is cooled by executing the cooling operation mode.

[0038] In the cooling operation mode, the control device 200 opens the pressure reducing devices 13a and 13c, opens the flow path opening / closing valve 20b, and fully closes the pressure reducing device 13b and the flow path opening / closing valves 20a and 20c.

[0039] 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 path 10b and passes through the outdoor heat exchanger 17. The refrigerant that dissipates heat into the outside air while passing through the outdoor heat exchanger 17 flows into refrigerant flow paths 10c and 10d and enters the accumulator 15 from the high-pressure inlet side 15a. The high-temperature, high-pressure refrigerant that has entered the accumulator 15 exchanges heat with the low-temperature, low-pressure refrigerant inside the accumulator 15 as it passes through the flat tubes 15b. The refrigerant that has passed through the flat tubes 15b flows into refrigerant flow paths 10e and 10i from the high-pressure outlet side 15c and passes through the evaporator 16. The refrigerant that has passed through the evaporator 16 flows into refrigerant flow paths 10j, 10k, and 10h and enters the accumulator 15 from the low-pressure inlet side 15d. The low-temperature, low-pressure refrigerant that has flowed into the accumulator 15 flows from the low-pressure outlet side 15 e into the refrigerant flow path 10 n and then into the compressor 11 .

[0040] That is, refrigerant flow paths 10a, 10b, 10c, 10d, 10e, 10i, 10j, 10k, 10h, and 10n form a circulation path in which the refrigerant that has passed through the compressor 11 passes through the interior condenser 12. As a result, the refrigerant that has been reduced to a low temperature and pressure by the pressure reducing device 13b passes through the evaporator 16, and the interior of the vehicle is cooled by the air cooled by the evaporator 16. At this time, the air mix damper 150 closes the interior condenser passage 121, so that the air cooled by the evaporator 16 passes through the bypass passage 122 to cool the interior of the vehicle.

[0041] [Accumulator Failure Detection Mode] In this embodiment, carbon dioxide refrigerant is used as the refrigerant. However, because carbon dioxide refrigerant has a lower critical point than other types of refrigerants, condensation of the refrigerant is less likely to occur on the high-pressure side, resulting in disadvantages in cooling and heating performance. For this reason, in this embodiment, flat tubes 15b are provided in the accumulator 15 as a heat exchanger. Refrigerant passing through the flat tubes 15b exchanges heat with low-temperature, low-pressure refrigerant inside the accumulator 15, thereby facilitating condensation of the refrigerant. Furthermore, providing a heat exchanger in the accumulator 15 prevents the vehicle air conditioning system 1 from becoming larger. However, because the accumulator 15 does not include electronic components, it is necessary to perform failure detection of the accumulator 15 without relying on electronic components. Therefore, in this embodiment, the control device 200 can detect a failure of the accumulator 15 by executing the accumulator failure detection mode in addition to other failure detection modes.

[0042] 3 shows an example of a process performed when the control device 200 executes the accumulator failure detection mode in addition to the execution of other failure detection modes. This process is executed as an interrupt when the automotive air conditioner 1 is started and at regular intervals.

[0043] 3, the control device 200 executes a sensor failure detection mode (S1). In the sensor failure detection mode, the control device 200 detects whether a failure has occurred in a sensor related to the refrigerant circulating through the refrigerant circuit 10. In this embodiment, in the sensor failure detection mode, failures in the refrigerant temperature sensor 230 and the refrigerant pressure sensor 240 can be detected.

[0044] Next, the control device 200 determines whether or not a sensor failure has been detected in the sensor failure detection mode (S2).

[0045] The control device 200 can detect failures of the refrigerant temperature sensor 230 and the refrigerant pressure sensor 240 by determining whether or not detection information is input from the refrigerant temperature sensor 230 and the refrigerant pressure sensor 240 .

[0046] If the control device 200 detects a sensor failure in the sensor failure detection mode (S2: Yes), the control device 200 ends the process and transitions to the error mode. In the error mode, the control device 200 displays an error message, etc.

[0047] Next, if the control device 200 does not detect a sensor failure in the sensor failure detection mode (S2: No), it executes the component failure detection mode (S3).

[0048] In the component failure detection mode, the control device 200 detects whether or not a failure has occurred in a component related to the refrigerant circulating through the refrigerant circuit 10. In this embodiment, in the component failure detection mode, failures in the compressor 11, the pressure reducing devices 13a, 13b, and 13c, and the flow path opening / closing valves 20a, 20b, and 20c can be detected.

[0049] Next, the control device 200 determines whether or not a component failure has been detected in the component failure detection mode (S4).

[0050] The control device 200 can detect component failure by determining whether the refrigerant pressure and temperature at the location of each component are within appropriate ranges based on detection information from the refrigerant temperature sensor 230 and the refrigerant pressure sensor 240.

[0051] Then, in the sensor failure detection mode of step S1, the control device 200 detects that there are no abnormalities in the refrigerant temperature sensor 230 and the refrigerant pressure sensor 240, and then detects a component failure, so it can accurately determine whether a component failure has occurred.

[0052] If the control device 200 detects a component failure in the component failure detection mode (S4: Yes), the control device 200 ends the process and transitions to the error mode. In the error mode, the control device 200 displays an error message, etc.

[0053] Next, if the control device 200 does not detect a sensor failure in the component failure detection mode (S4: No), it executes the refrigerant leakage failure detection mode (S5).

[0054] In the refrigerant leakage failure detection mode, the control device 200 detects whether or not a leak has occurred in the refrigerant circulating through the refrigerant circuit 10. In this embodiment, a refrigerant leak can be detected in the refrigerant flow paths 10a, 10b, 10c, 10e, 10f, 10g, 10j, 10k, 10m, and 10n.

[0055] Next, the control device 200 determines whether or not a refrigerant leakage failure has been detected in the refrigerant leakage failure detection mode (S6).

[0056] The control device 200 can detect a refrigerant leak by determining whether the pressure and temperature of the refrigerant in the refrigerant flow path into which the refrigerant is flowing are within an appropriate range based on the detection information from the refrigerant temperature sensor 230 and the refrigerant pressure sensor 240 and the operating status of each component of the refrigerant circuit 10.

[0057] The control device 200 detects that there are no abnormalities in the refrigerant temperature sensor 230 and the refrigerant pressure sensor 240 in the sensor failure detection mode of step S1, and then detects that there are no abnormalities in each component in the component failure detection mode of step S3 before detecting a refrigerant leak, so it can accurately determine whether a refrigerant leak has occurred. Note that if a refrigerant leak has occurred, the refrigerant pressure in the refrigerant circuit 10 will drop.

[0058] If the control device 200 detects a refrigerant leak failure in the refrigerant leak failure detection mode (S6: Yes), the control device 200 ends the process and transitions to the error mode. In the error mode, the control device 200 displays an error message, etc.

[0059] Next, if the control device 200 does not detect a refrigerant leakage failure in the refrigerant leakage failure detection mode (S6: No), the control device 200 operates the compressor 11 in the cooling operation mode (S7).

[0060] Next, the control device 200 determines whether there is a difference in pressure between the high-pressure side refrigerant and the low-pressure side refrigerant based on whether the pressure detected by the low-pressure side refrigerant pressure sensor 240a exceeds a predetermined pressure (S8).

[0061] The predetermined pressure is the pressure detected by the low-pressure-side refrigerant pressure sensor 240a when there is a difference between the high-pressure side refrigerant pressure and the low-pressure side refrigerant pressure. When the high-pressure side refrigerant pressure decreases and the low-pressure side refrigerant pressure increases, and the difference between the high-pressure side refrigerant pressure and the low-pressure side refrigerant pressure disappears, the pressure detected by the low-pressure side refrigerant pressure sensor 240a exceeds the predetermined pressure. Therefore, whether there is a difference between the high-pressure side refrigerant pressure and the low-pressure side refrigerant pressure can be determined based on whether the pressure detected by the low-pressure side refrigerant pressure sensor 240a exceeds the predetermined pressure.

[0062] The specified pressure is set, for example, based on the pressure detected by the low-pressure side refrigerant pressure sensor 240a during a specified time period while maintaining a pressure difference between the high-pressure side refrigerant pressure and the low-pressure side refrigerant pressure.

[0063] If the pressure detected by the low-pressure side refrigerant pressure sensor 240a exceeds a predetermined pressure, the control device 200 determines that there is no difference between the pressure of the high-pressure side refrigerant and the pressure of the low-pressure side refrigerant (S8: No) and detects a failure of the flat tube 15b, which is the heat exchanger (S9).

[0064] That is, if the connection portion of the flat tube 15b becomes disconnected inside the accumulator 15, the high-temperature, high-pressure refrigerant flowing in from the refrigerant flow path 10d will leak into the low-pressure section inside the accumulator 15. As a result, there will be no difference in the pressure of the refrigerant on the high-pressure side and the low-pressure side, and by determining that there is no difference in the pressure of the refrigerant on the high-pressure side and the low-pressure side, a failure of the flat tube 15b can be detected.

[0065] In particular, because this embodiment uses a high-pressure carbon dioxide refrigerant, a failure of the flat tubes 15b results in significant fluctuations in refrigerant pressure. Furthermore, because the flat tubes 15b are fixed by brazing in this embodiment, there is a possibility that the connection of the flat tubes 15b may come loose due to vibration or other factors. Therefore, when detecting a failure of the flat tubes 15b, it is preferable to determine whether there is a difference between high and low pressures of the refrigerant. Furthermore, if a failure occurs in the flat tubes 15b, the refrigerant pressure in the refrigerant circuit 10 increases.

[0066] Furthermore, since the sensor failure detection mode of step S1 detects that there is no abnormality in the low-pressure side refrigerant pressure sensor 240a and then detects a failure in the flat tubes 15b using the low-pressure side refrigerant pressure sensor 240a, it is possible to accurately determine a failure in the flat tubes 15b. Furthermore, the component failure detection mode of step S3 detects that there is no abnormality in each component, and furthermore, the refrigerant leak detection mode of step S5 detects that there is no refrigerant leak, and then it is possible to accurately determine that the cause of the lack of pressure difference (i.e., the location of the failure) is a failure in the flat tubes 15b.

[0067] If the pressure detected by the low-pressure side refrigerant pressure sensor 240a does not exceed the predetermined pressure, the control device 200 determines that there is a difference between the pressure of the high-pressure side refrigerant and the pressure of the low-pressure side refrigerant (S8: Yes), determines that the flat tube 15b is not malfunctioning, and terminates the processing.

[0068] As described above, in this embodiment, the control device 200 executes the processes of steps S7 to S9 to execute the accumulator failure detection mode.

[0069] In this embodiment, an example is given in which a failure of the flat tube 15b is detected when the pressure detected by the low-pressure side refrigerant pressure sensor 240a exceeds a predetermined pressure, but a failure of the flat tube 15b may also be detected by determining whether there is a high-low pressure difference in the refrigerant pressure based on the difference between the pressure detected by the low-pressure side refrigerant pressure sensor 240a and the pressure detected by the high-pressure side refrigerant pressure sensor 240b.

[0070] In the present embodiment, an example has been given in which the sensor failure detection mode, component failure detection mode, and refrigerant leak detection mode are executed before the accumulator failure detection mode, but other failure detection modes do not necessarily have to be executed before the accumulator failure detection mode. Furthermore, some of the sensor failure detection mode, component failure detection mode, and refrigerant leak detection mode may be executed before the accumulator failure detection mode. Furthermore, a failure detection mode different from the sensor failure detection mode, component failure detection mode, and refrigerant leak detection mode may be executed before the accumulator failure detection mode. Furthermore, the sensor failure detection mode, component failure detection mode, and refrigerant leak detection mode do not have to be processed separately, and multiple failure detection modes may be processed in the same step.

[0071] As described above, it is possible to detect refrigerant leakage from the flat tubes 15b that exchange heat with the refrigerant inside the accumulator 15 based on the pressure detected by the low-pressure side refrigerant pressure sensor 240a, and therefore it is possible to detect malfunctions such as a decrease in the amount of refrigerant circulating in the refrigerant circuit 10 or an abnormal increase in the suction pressure of the compressor 11 due to the suction of high-pressure refrigerant.

[0072] Furthermore, by executing the accumulator failure detection mode after executing multiple failure detection modes, a failure in the flat tubes 15b is detected after detecting that there are no abnormalities in the sensors, so it is possible to accurately determine whether or not the flat tubes 15b are faulty. Furthermore, since a failure is detected after detecting that there are no component failures or refrigerant leaks, it is possible to accurately determine that the fault is in the flat tubes 15b. This prevents erroneous detection of a failure in the flat tubes 15b.

[0073] [Advantages of the Present Embodiment] (1) The vehicle air conditioning system 1 includes the refrigerant circuit 10 including the accumulator 15 having a heat exchange unit that exchanges heat with the refrigerant therein, the low-pressure side refrigerant pressure sensor 240a serving as a pressure sensor that detects the pressure downstream of the accumulator 15, and the control device 200, wherein the control device 200 has an accumulator failure detection mode that detects a failure in the heat exchange unit based on the pressure detected by the low-pressure side refrigerant pressure sensor 240a (S7 to S9 in FIG. 3). This makes it possible to detect refrigerant leakage from the heat exchange unit that exchanges heat with the refrigerant inside the accumulator 15, and to detect malfunctions such as a decrease in the refrigerant circulation amount or an abnormal increase in the suction pressure of the compressor 11.

[0074] (2) The control device 200 has multiple failure detection modes, including an accumulator failure detection mode (S1, S3, and S5 in FIG. 3), and executes the accumulator failure detection mode after executing multiple failure detection modes (S7 to S9 are executed after S1, S3, and S5 in FIG. 3). Therefore, it is possible to detect a failure in the heat exchange unit after determining that the sensor used to detect the failure in the heat exchange unit is normal, and therefore it is possible to accurately determine whether or not the heat exchange unit has failed. This prevents erroneous detection of a failure in the heat exchange unit.

[0075] (3) The refrigerant is carbon dioxide refrigerant, and in the accumulator failure detection mode, the control device 200 detects a failure of the heat exchange unit based on the difference between the pressure of the high-pressure refrigerant and the pressure of the low-pressure refrigerant (S8 in FIG. 3). Therefore, it is possible to detect refrigerant leakage from the heat exchange unit that exchanges heat with the refrigerant inside the accumulator 15, and to detect malfunctions such as a decrease in the refrigerant circulation amount or an abnormal increase in the suction pressure of the compressor 11.

[0076] (4) In the accumulator failure detection mode, the control device 200 detects a failure of the heat exchange unit when the pressure detected by the low-pressure side refrigerant pressure sensor 240a exceeds a predetermined pressure. This makes it possible to detect refrigerant leakage from the heat exchange unit that exchanges heat with the refrigerant inside the accumulator 15, and to detect malfunctions such as a decrease in the refrigerant circulation amount or an abnormal increase in the suction pressure of the compressor 11.

[0077] (5) The heat exchange unit is provided in the accumulator 15 and includes a plurality of flat tubes 15b. Therefore, it is possible to easily detect a failure in the accumulator, which includes a heat exchange unit made up of a plurality of flat tubes 15b and is relatively susceptible to failures such as refrigerant leakage.

[0078] 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.

[0079] 1: Vehicle air conditioning system 10: Refrigerant circuit, 11: Compressor, 12: Interior condenser, 13a, 13b, 13c, 13d: Pressure reducing device, 14: Low temperature side heat exchanger, 15: Accumulator, 16: Evaporator, 17: Exterior heat exchanger 100: HVAC unit, 110: Case, 120: Air flow passage, 121: Interior condenser passage, 122: Bypass passage, 150: Air mix damper

Claims

1. A vehicle air conditioning system comprising: a refrigerant circuit including an accumulator having a heat exchange unit that exchanges heat with the refrigerant inside; a pressure sensor that detects the pressure downstream of the accumulator; and a control device, wherein the control device has an accumulator failure detection mode that detects a failure in the heat exchange unit based on the pressure detected by the pressure sensor.

2. The vehicle air conditioning system according to claim 1, wherein the control device has a plurality of failure detection modes including an accumulator failure detection mode, and executes the accumulator failure detection mode after executing the plurality of failure detection modes.

3. The vehicular air conditioning system according to claim 1, characterized in that the refrigerant is carbon dioxide refrigerant, and the control device, in an accumulator failure detection mode, detects a failure in the heat exchange unit based on the difference between the pressure of the refrigerant on the high-pressure side and the pressure of the refrigerant on the low-pressure side.

4. The vehicle air conditioning system according to claim 1, wherein the control device detects a failure of the heat exchanger when the pressure detected by the pressure sensor exceeds a predetermined pressure in the accumulator failure detection mode.

5. The vehicle air conditioning system according to claim 1, wherein the heat exchanger is provided within the accumulator, and the heat exchanger has a plurality of flat tubes.

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