Vehicle air conditioning unit

Abstract

The system detects leaks of hydrocarbon refrigerants from the refrigerant circuit and limits the start of the compressor. [Solution] The in-vehicle air conditioning system 12 includes a refrigerant circuit R, a first coolant circuit C1, a second coolant circuit C2, a housing 60 covering the refrigerant circuit R, a gas sensor 80 inside the housing 60, and a controller 50 that controls the compressor 20 of the refrigerant circuit R. The refrigerant circuit R has a compressor 20, a condenser for heat dissipation, an expansion valve, and an evaporator for heat absorption, through which a hydrocarbon refrigerant circulates. The first coolant circuit C1 has a radiator through which coolant heated by the condenser of the refrigerant circuit R circulates. The second coolant circuit C2 has a cooler core that cools the conditioned air through which coolant cooled by the evaporator of the refrigerant circuit R circulates. When the controller 50 receives a command to start the compressor 20, if the gas concentration detected by the gas sensor 80 is higher than a predetermined concentration, it avoids starting the compressor 20.

Description

Technical Field

[0001] This specification relates to an in-vehicle air conditioner, and particularly discloses an in-vehicle air conditioner using a hydrocarbon refrigerant.

Background Art

[0002] In recent years, as a refrigerant for air conditioners, the use of hydrocarbon refrigerants (HC refrigerants) such as propane with a low global warming potential has been considered. Since HC refrigerants are flammable, configurations for preventing refrigerant leakage and ensuring safety during refrigerant leakage have been studied.

[0003] Patent Document 1 discloses a technique related to a cooler for cooling a fuel cell, where the cooler includes a pump that sends a refrigerant to the fuel cell, and refrigerant leakage is detected from the power consumption of the pump.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] In an in-vehicle air conditioner using a hydrocarbon refrigerant, it is desired to detect leakage of the hydrocarbon refrigerant from the refrigerant circuit and restrict the startup of the compressor in the refrigerant circuit.

[0006] This specification discloses an in-vehicle air conditioner that can detect leakage of a hydrocarbon refrigerant from a refrigerant circuit and restrict the startup of a compressor.

Means for Solving the Problems

[0007] The in-vehicle air conditioning system disclosed herein comprises a refrigerant circuit through which a hydrocarbon refrigerant circulates, having a compressor, a condenser for heat dissipation, an expansion valve, and an evaporator for heat absorption; a first coolant circuit having a radiator through which a coolant heated by the condenser of the refrigerant circuit circulates; a second coolant circuit having a cooler core for cooling conditioned air through which a coolant cooled by the evaporator of the refrigerant circuit circulates; a housing covering the refrigerant circuit; a gas sensor disposed within the housing for detecting the gas concentration of the refrigerant outside the refrigerant circuit; and a controller for controlling the compressor. When the controller receives a command to start the compressor, if the gas concentration detected by the gas sensor is higher than a predetermined concentration, the controller avoids starting the compressor.

[0008] In this configuration, the refrigerant circuit dissipates heat to the coolant in the first coolant circuit and absorbs heat to the coolant in the second coolant circuit, allowing the refrigerant circuit to be concentrated in a relatively small area and housed within the enclosure. Furthermore, if refrigerant leaks from the refrigerant circuit, it can be detected by a gas sensor inside the enclosure. In this case, if the gas concentration detected by the gas sensor is higher than a predetermined concentration, the compressor can be avoided.

[0009] In the in-vehicle air conditioning system of this disclosure, the predetermined concentration is a second concentration, and a first concentration lower than the second concentration may also be predetermined. Furthermore, when the controller receives a command to start the compressor, it may start the compressor if the gas concentration detected by the gas sensor is lower than the first concentration.

[0010] This configuration may allow the compressor to be started within a housing whose safety has been confirmed by a gas sensor.

[0011] The in-vehicle air conditioning system of the present disclosure may include an internal temperature sensor for detecting the temperature inside the refrigerant circuit and an external temperature sensor for detecting the temperature outside the refrigerant circuit. The controller may, upon receiving a compressor start command, avoid starting the compressor if the gas concentration detected by the gas sensor is greater than or equal to the first concentration and less than or equal to the second concentration, and the temperature detected by the internal temperature sensor is lower than a temperature threshold obtained by subtracting a predetermined temperature from the temperature detected by the external temperature sensor; otherwise, start the compressor.

[0012] With this configuration, if the gas concentration detected by the gas sensor is above the first concentration and below the second concentration, it is possible to further check for refrigerant leaks and avoid starting the compressor accordingly. If there is a refrigerant leak from the refrigerant circuit, the internal temperature of the refrigerant circuit will be lower than the external temperature of the refrigerant circuit because the leaked refrigerant absorbs heat when it vaporizes. With the above configuration, if the internal temperature of the refrigerant circuit is lower than a temperature threshold obtained by subtracting a predetermined temperature from the external temperature of the refrigerant circuit, it is possible to determine that there is a possibility of a refrigerant leak and avoid starting the compressor.

[0013] The in-vehicle air conditioning system of this disclosure may include an internal pressure sensor for detecting the pressure inside the refrigerant circuit, an external temperature sensor for detecting the temperature outside the refrigerant circuit, and a storage device for storing a table representing the saturated vapor pressure curve of the refrigerant. The controller may use the saturated vapor pressure curve table to obtain the pressure of the refrigerant corresponding to the temperature detected by the external temperature sensor as the expected pressure. When the controller receives a compressor start command, if the gas concentration detected by the gas sensor is greater than or equal to the first concentration and less than or equal to the second concentration, and the pressure detected by the internal pressure sensor is lower than a pressure threshold obtained by subtracting a predetermined pressure from the expected pressure, the controller may avoid starting the compressor; otherwise, the controller may start the compressor.

[0014] In this configuration, if the gas concentration detected by the gas sensor is above the first concentration and below the second concentration, the presence or absence of a refrigerant leak can be checked, and the compressor can be avoided accordingly. Before the compressor starts, the refrigerant inside the refrigerant circuit is in a vapor-liquid equilibrium state, so the relationship between the temperature and pressure of the refrigerant inside the refrigerant circuit follows the saturated vapor pressure curve of that refrigerant. Also, before the compressor starts, the internal temperature and external temperature of the refrigerant circuit are the same or close, so the internal pressure of the refrigerant circuit can be estimated from the external temperature of the refrigerant circuit (estimated internal temperature of the refrigerant circuit) using the saturated vapor pressure curve described above. This estimated internal pressure (called the expected pressure) is the internal pressure of the refrigerant circuit when there is no refrigerant leak. On the other hand, if there is a refrigerant leak in the refrigerant circuit, the internal pressure of the refrigerant circuit will be lower than the expected pressure. In the above configuration, the presence or absence of a refrigerant leak is checked using this principle. Specifically, with the above configuration, if the pressure detected by the internal pressure sensor that detects the pressure inside the refrigerant circuit is lower than a pressure threshold obtained by subtracting a predetermined pressure from the expected pressure, it can be determined that there is a possibility of refrigerant leakage, and the compressor can be avoided.

[0015] In the vehicle air conditioning system of the present disclosure, the controller may, after starting the compressor, stop the compressor if, while the compressor is operating, the gas concentration detected by the gas sensor increases and its rate of increase per unit time exceeds a predetermined rate of increase.

[0016] This configuration makes it possible to stop the compressor before the refrigerant gas concentration inside the enclosure becomes too high when a refrigerant leak occurs in the refrigerant circuit.

[0017] In the vehicle air conditioning system of this disclosure, the hydrocarbon refrigerant may be propane or a refrigerant mainly composed of propane.

[0018] The vehicles disclosed herein are equipped with the above-described on-board air conditioning system. [Effects of the Invention]

[0019] According to the technology disclosed in this specification, it is possible to detect a leak of a hydrocarbon refrigerant from a refrigerant circuit and restrict the startup of a compressor.

Brief Description of the Drawings

[0020] [Figure 1] It is a schematic diagram showing the configuration of an air conditioner. [Figure 2] It is a perspective view showing a refrigerant module. [Figure 3] It is a block diagram showing the configuration of an air conditioner. [Figure 4] It is a flowchart showing the startup control of a compressor. [Figure 5] It is a flowchart showing another startup control of a compressor. [Figure 6] It is a flowchart showing the control during the operation of a compressor. [Figure 7] It is a diagram illustrating the saturation vapor pressure curve of a refrigerant.

Modes for Carrying Out the Invention

[0021] <Preamble> Hereinafter, embodiments will be described with reference to the drawings. In all the drawings, the same reference numerals are assigned to equivalent elements, and redundant descriptions are omitted.

[0022] The air conditioner is mounted on a vehicle such as an automobile. In the embodiments described below, the type of vehicle on which the air conditioner is mounted is not limited. For example, the vehicle may be an engine vehicle with an engine as a power source, an electric vehicle with a motor as a power source, or a hybrid electric vehicle or a plug-in hybrid electric vehicle equipped with both an engine and a motor. Further, the vehicle may be a fuel cell vehicle equipped with a fuel cell, or a battery electric vehicle that runs on electric power stored in a battery.

[0023] The air conditioning system is equipped with a refrigerant circuit through which a hydrocarbon refrigerant (referred to as an HC refrigerant) circulates. HC refrigerants are flammable. Examples of HC refrigerants include propane, butane, isobutane, ethane, ethylene, and propylene. In the refrigerant circuit, one of these HC refrigerants, or a mixture of two or more of these HC refrigerants, may be used. Alternatively, a mixed refrigerant may be used in the refrigerant circuit, which mainly consists of one or more HC refrigerants, along with other refrigerants and various additives. For example, in the refrigerant circuit, propane, or a refrigerant mainly consisting of propane, along with at least one of other refrigerants and additives (a refrigerant mainly composed of propane), may be used. An example of an HC refrigerant may be R290. In this specification, a hydrocarbon refrigerant means a pure hydrocarbon refrigerant or a refrigerant mainly composed of a hydrocarbon refrigerant.

[0024] The refrigerant circuit serves as the heat source for the air conditioning system. The refrigerant circuit comprises, in order along the direction of refrigerant flow, a compressor, a condenser for heat dissipation, an expansion valve, and an evaporator for heat absorption. A receiver may be provided between the condenser and the expansion valve. An accumulator may also be provided between the evaporator and the compressor.

[0025] An air conditioning system may include a high-temperature coolant circuit through which a coolant heated by a condenser in the refrigerant circuit circulates, and a low-temperature coolant circuit through which a coolant cooled by an evaporator in the refrigerant circuit circulates. The coolant is a heat transfer medium, and the high-temperature coolant circuit and the low-temperature coolant circuit are heat transfer medium circuits, respectively.

[0026] In the embodiments described below, as shown in Figure 1, the air conditioning system 12 includes a first coolant circuit C1 as a high-temperature coolant circuit and a second coolant circuit C2 as a low-temperature coolant circuit. The coolant in the first and second coolant circuits C1 and C2 may be cooling water. That is, the coolant may be water without additives, water mixed with additives such as antifreeze and preservatives, or coolant liquid. Furthermore, the coolant may be a liquid heat transfer medium such as oil, and is not limited to that.

[0027] In the embodiments described below, the refrigerant circuit is located under the vehicle's front hood. Hereafter, regardless of the presence or type of power source (engine, motor, etc.) under the front hood, the area under the front hood will be referred to as the "engine room".

[0028] <Embodiment> Figure 1 is a schematic diagram showing the configuration of an air conditioning system 12 according to an embodiment. The air conditioning system 12 provides air conditioning for the interior of a vehicle. As shown in Figure 1, the air conditioning system 12 comprises a refrigerant circuit R which serves as a heat source, a first coolant circuit C1, a second coolant circuit C2, and an air conditioning unit 70. The first coolant circuit C1 circulates a first coolant heated by the refrigerant in the refrigerant circuit R. The second coolant circuit C2 circulates a second coolant cooled by the refrigerant in the refrigerant circuit R. The air conditioning unit 70 supplies air cooled by the second coolant circulating in the second coolant circuit C2 into the vehicle interior.

[0029] The refrigerant circuit R is a closed circuit that circulates a hydrocarbon refrigerant (hereinafter also simply referred to as refrigerant) by sequentially connecting a compressor 20, a condenser 22, a receiver 28, an expansion valve 24, and an evaporator 26 via refrigerant piping (refrigerant flow path).

[0030] The air conditioning unit 12 includes a heat exchanger 30. The heat exchanger 30 is integrated with the condenser 22 of the refrigerant circuit R and exchanges heat between the refrigerant of the refrigerant circuit R and the first coolant of the first coolant circuit C1. The heat exchanger 30 is a water-cooled condenser. The heat exchanger 30 may be, for example, a plate heat exchanger.

[0031] The first coolant circuit C1 is a closed circuit that circulates the first coolant, consisting of a water pump 32, a heat exchanger 30, and a radiator 34 connected sequentially by coolant piping. The radiator 34 is a heat exchanger that exchanges heat between the first coolant and the vehicle's airflow Wtr. In the first coolant circuit C1, the first coolant, pressurized by the water pump 32, becomes hot due to heat dissipation from the refrigerant in the condenser 22 of the refrigerant circuit R as it passes through the heat exchanger 30. The hot first coolant is then sent to the radiator 34, where it is cooled by the vehicle's airflow Wtr.

[0032] Furthermore, the air conditioning unit 12 includes a heat exchanger 40. The heat exchanger 40 is integrated with the evaporator 26 of the refrigerant circuit R and exchanges heat between the refrigerant of the refrigerant circuit R and the second coolant of the second coolant circuit C2. The heat exchanger 40 may be, for example, a plate heat exchanger.

[0033] The second coolant circuit C2 is a closed circuit that circulates the second coolant, with the water pump 42, heat exchanger 40, and cooler core 72 sequentially connected by coolant piping. The cooler core 72 is a heat exchanger located in the air passage 75 of the air conditioning unit 70, which exchanges heat between the second coolant and the conditioned air (Wac). In the second coolant circuit C2, the second coolant, pressurized by the water pump 42, becomes cold due to the heat absorption of the refrigerant in the evaporator 26 of the refrigerant circuit R as it passes through the heat exchanger 40. The cold second coolant is then sent to the cooler core 72, where it cools the conditioned air (Wac).

[0034] In the refrigerant circuit R, the refrigerant circulates as follows: The compressor 20 discharges high-pressure gaseous refrigerant, which dissipates heat and liquefies and condenses in the condenser 22 by exchanging heat with the first coolant of the first coolant circuit C1, which passes through the heat exchanger 30, becoming high-pressure liquid refrigerant. The high-pressure liquid refrigerant flowing out of the condenser 22 is depressurized and expanded by the expansion valve 24 via the receiver 28, becoming low-pressure refrigerant, and flows into the evaporator 26. The low-pressure refrigerant flowing into the evaporator 26 evaporates by exchanging heat with the second coolant of the second coolant circuit C2, which passes through the heat exchanger 40, becoming gaseous refrigerant, flowing out of the evaporator 26, and returning to the compressor 20.

[0035] The air conditioning unit 70 comprises a blower 76 and an air passage 75 formed by a case (not shown). Inside the air passage 75, the blower 76, a cooler core 72, and a heater core 74 are arranged in order from the direction of airflow. The heater core 74 is a heat exchanger to which, for example, engine coolant or coolant heated by a PTC heater for water heating is supplied. The heater core 74 may also be configured to be supplied with coolant heated by the heat exchanger 30.

[0036] The blower 76 introduces air into the air passage 75 from an air intake (not shown) and blows this air through the cooler core 72 and heater core 74, thereby supplying temperature-controlled air to the passenger compartment. An air mix door 78 is provided inside the air passage 75, and the air mix door 78 adjusts the ratio of air that has passed through the cooler core 72 to that which flows to the heater core 74. The air conditioning unit 70 may employ conventional HVAC (Heating, Ventilation, and Air Conditioning) technology. The air conditioning unit 70 is located, for example, between the instrument panel and the dashboard of the vehicle.

[0037] Figure 2 is a perspective view showing the refrigerant module RM. The refrigerant circuit R is integrated to constitute the refrigerant module RM. Specifically, the refrigerant module RM is a unit that integrates the equipment and flow path within the dashed line in Figure 1 of the air conditioning system 12.

[0038] As shown in Figure 2, the refrigerant module RM includes a plate 100. The plate 100 is a fixed member to which multiple pieces of equipment are fixed. The plate 100 has a rectangular shape when viewed from above and has a certain thickness. The material of the plate 100 may be, for example, aluminum. The heat exchanger 30, expansion valve 24, and heat exchanger 40 are fixed to the upper surface 102 of the plate 100. The compressor 20 and receiver 28 are fixed to the lower surface 104 of the plate 100.

[0039] The plate 100 has a flow path (not shown) in the form of a tunnel. Specifically, the plate 100 has a refrigerant flow path for the refrigerant circuit R, a coolant flow path for a part of the first coolant circuit C1 (a first coolant flow path communicating with the heat exchanger 30), and a coolant flow path for a part of the second coolant circuit C2 (a second coolant flow path communicating with the heat exchanger 40). In addition to the flow paths inside the plate 100, or instead, the refrigerant module RM may be provided with piping and components for at least one of the refrigerant flow path and the coolant flow path on the outside of the plate 100.

[0040] As shown in Figure 2, the refrigerant module RM is equipped with ports P1 to P4. Ports P1 to P4 are located on the underside of one longitudinal end of the plate 100. Ports P1 and P2 communicate with the first coolant flow path inside the plate 100, and the piping of the first coolant circuit C1 is connected to them. Ports P3 and P4 communicate with the second coolant flow path inside the plate 100, and the piping of the second coolant circuit C2 is connected to them.

[0041] Figure 3 is a block diagram showing the configuration of the air conditioning unit 12, schematically showing a cross-section of the housing 60. The air conditioning unit 12 comprises a housing 60. The housing 60 comprises a housing body 60a and a lid 60b. The refrigerant module RM is housed inside the housing 60. The lid 60b is removed from the housing body 60a, the refrigerant module RM is housed inside the housing body 60a, and then the lid 60b is attached to the housing body 60a. The refrigerant module RM is fixed to the inner surface of the housing body 60a via a bracket (not shown). The piping of the first and second coolant circuits C1 and C2 penetrates the side plate of the housing body 60a and is connected to ports P1 to P4 (see Figure 2) of the refrigerant module RM.

[0042] The top surface of the lid 60b may have one or more openings. Furthermore, the housing 60 may be constructed without the lid 60b.

[0043] The housing 60 and the refrigerant module RM are located in the engine compartment of the vehicle. The bottom plate of the housing body 60a has a hole 62, as shown in Figure 3. A hose 64 extending downwards from the vehicle is connected to this hole 62. The hose 64 extends from the hole 62 in the bottom plate toward the bottom of the vehicle body. The end of the hose 64 (not shown) may be fixed to a vehicle body structure located at the lower (or bottom) part of the engine compartment.

[0044] This hose 64 allows refrigerant to be guided downwards through the hose 64 in the event of a leak from the refrigerant circuit R. Since refrigerant (HC-based refrigerant) is generally heavier than air, it flows downwards through the hose 64. This allows the refrigerant to be released to a relatively safe location at the bottom of the vehicle.

[0045] The air conditioning unit 12 is equipped with a gas sensor 80. The gas sensor 80 is located inside the housing 60 and detects the refrigerant gas concentration outside the refrigerant circuit R. The gas sensor 80 is located, for example, near the bottom of the housing 60.

[0046] Furthermore, the air conditioning unit 12 includes an external temperature sensor 82, an internal temperature sensor 92, and an internal pressure sensor 94.

[0047] The external temperature sensor 82 is a temperature sensor that detects the temperature outside the refrigerant circuit R. The external temperature sensor 82 should be installed in a location where it will not be affected by refrigerant when refrigerant leaks from the refrigerant circuit R. In other words, the external temperature sensor 82 should be installed in a location where it can detect the temperature of air that is not affected by the refrigerant, rather than the air whose temperature drops due to the vaporization of the refrigerant when refrigerant leaks from the refrigerant circuit R. Since refrigerant (HC-based refrigerant) is generally heavier than air, it flows downwards within the housing 60. Therefore, the external temperature sensor 82 should be installed above the refrigerant circuit R inside the housing 60, or above the lower end of the refrigerant circuit R, as shown in Figure 3, for example. Alternatively, a partition wall may be provided inside the housing 60 to separate the refrigerant circuit R from the external temperature sensor 82. Alternatively, an inner wall may be provided inside the housing 60 to form a closed space in which the external temperature sensor 82 is located. The external temperature sensor 82 may also be installed on the outside of the housing 60.

[0048] The internal temperature sensor 92 is a temperature sensor that detects the temperature inside the refrigerant circuit R. The internal temperature sensor 92 detects, for example, the temperature inside the refrigerant piping. The internal pressure sensor 94 is a pressure sensor that detects the pressure inside the refrigerant circuit R. The internal pressure sensor 94 detects, for example, the pressure inside the refrigerant piping.

[0049] The air conditioning unit 12 includes a controller 50. The controller 50 may include a microcomputer, for example, an ECU (Electronic Control Unit). The controller 50 includes a processor 52 and a storage device 54. The processor 52 includes a CPU (Central Processing Unit), which performs various calculations and controls by operating according to the programs and control data stored in the storage device 54. The storage device 54 may include ROM (Read Only Memory), RAM (Random Access Memory), flash memory, etc. The storage device 54 stores a table 56 representing the saturated vapor pressure curve of the refrigerant. This table 56 is used in the embodiment described with reference to Figure 5.

[0050] The controller 50 controls the compressor 20 of the refrigerant circuit R. The controller 50 receives input from the gas sensor 80 (detected gas concentration), the external temperature sensor 82 (detected temperature), the internal temperature sensor 92 (detected temperature), and the internal pressure sensor 94 (detected pressure).

[0051] Furthermore, the controller 50 receives a start command for the compressor 20. This start command is a command to start the operation of the compressor 20. The start command for the compressor 20 is sent, for example, from the control panel (not shown) or from the ECU connected to the control panel when the user turns the air conditioning system 12 from off to on using the control panel. Alternatively, the start command for the compressor 20 may be sent from the computer when the air conditioning system 12 operates automatically using a computer such as an ECU (operating in auto mode).

[0052] Figure 4 is a flowchart showing the start-up control of the compressor 20. When the controller 50 receives a start command for the compressor 20, it executes the control shown in Figure 4. Note that the internal pressure sensor 94 and table 56 are not used in this control.

[0053] In step S100, the controller 50 checks whether the detected gas concentration Gc of the gas sensor 80 is higher than a predetermined second concentration. This second concentration is stored in the memory device 54 beforehand. This second concentration is the refrigerant gas concentration set with safety in mind.

[0054] If the gas concentration Gc detected by the gas sensor 80 is higher than the second concentration (step S100: Yes), the controller 50 proceeds to step S110. In step S110, the controller 50 does not start the compressor 20. That is, the controller 50 keeps the compressor 20 stopped.

[0055] On the other hand, if the gas concentration Gc detected by the gas sensor 80 is less than or equal to the second concentration (step S100: No), the controller 50 proceeds to step S102. In step S102, the controller 50 checks whether the gas concentration Gc detected by the gas sensor 80 is lower than a predetermined first concentration. This first concentration is stored in the memory device 54 in advance. This first concentration is a gas concentration lower than the second concentration in step S100. The first concentration is the gas concentration of the refrigerant set with safety in mind.

[0056] If the gas concentration Gc detected by the gas sensor 80 is lower than the first concentration (step S102: Yes), the controller 50 proceeds to step S112. In step S112, the controller 50 starts the compressor 20. That is, the controller 50 starts the operation of the compressor 20.

[0057] On the other hand, if the gas concentration Gc detected by the gas sensor 80 is equal to or greater than the first concentration (step S102: No), the controller 50 proceeds to step S106. In step S106, the controller 50 calculates a temperature threshold Tth by subtracting a predetermined temperature prT from the temperature To detected by the external temperature sensor 82. The predetermined temperature prT is stored in the memory device 54 beforehand.

[0058] Next, in step S108, the controller 50 checks whether the temperature Ti detected by the internal temperature sensor 92 is lower than the temperature threshold Tth calculated in step S106. If the temperature Ti detected by the internal temperature sensor 92 is lower than the temperature threshold Tth (step S108: Yes), the controller 50 proceeds to step S110. In step S110, the controller 50 does not start the compressor 20. That is, the controller 50 keeps the compressor 20 stopped.

[0059] Figure 7 illustrates the saturated vapor pressure curve of a refrigerant. Although this startup control does not use the saturated vapor pressure curve of the refrigerant, if we focus on the "temperature" on the horizontal axis of Figure 7, we can see an example of the relationship between the "detected temperature To of the external temperature sensor 82", the "detected temperature Ti of the internal temperature sensor 92", and the "temperature threshold Tth" when the condition for step S108 in Figure 4 to be Yes is met.

[0060] On the other hand, in step S108 of Figure 4, if the temperature Ti detected by the internal temperature sensor 92 is greater than or equal to the temperature threshold Tth (step S108: No), the controller 50 proceeds to step S112. In step S112, the controller 50 starts the compressor 20.

[0061] According to the embodiment described above, since the refrigerant circuit R dissipates heat to the first coolant of the first coolant circuit C1 and absorbs heat to the second coolant of the second coolant circuit C2, the refrigerant circuit R can be concentrated in a relatively narrow area and housed in the housing 60, as shown in Figure 3. Furthermore, if refrigerant leaks from the refrigerant circuit R, the refrigerant can be detected by the gas sensor 80 inside the housing 60. In this case, if the gas concentration Gc detected by the gas sensor 80 is higher than a predetermined second concentration (step S100 in Figure 4: Yes), the start of the compressor 20 can be avoided (step S110).

[0062] Furthermore, according to the embodiment described above, if the gas concentration Gc detected by the gas sensor 80 is lower than the first concentration which is lower than the second concentration (step S102: Yes), the compressor 20 is started (step S112). Therefore, the compressor 20 can be started within the housing 60 whose safety has been confirmed by the gas sensor 80.

[0063] Furthermore, according to the embodiment described above, if the detected gas concentration Gc of the gas sensor 80 is greater than or equal to the first concentration and less than or equal to the second concentration (step S102: No), the presence or absence of a refrigerant leak can be checked, and the start of the compressor 20 can be avoided accordingly. If there is a refrigerant leak from the refrigerant circuit R, the internal temperature Ti of the refrigerant circuit R will be lower than the external temperature To of the refrigerant circuit R because the leaked refrigerant absorbs heat when it vaporizes. According to the embodiment described above, if the internal temperature Ti of the refrigerant circuit R is lower than the temperature threshold Tth obtained by subtracting a predetermined temperature prT from the external temperature To of the refrigerant circuit R (step S108: Yes), it can be determined that there is a possibility of a refrigerant leak, and the start of the compressor 20 can be avoided (step S110).

[0064] In another embodiment, when the controller 50 receives a command to start the compressor 20, if the gas concentration Gc detected by the gas sensor 80 is higher than a predetermined concentration (for example, the second concentration described above), it may avoid starting the compressor 20, and if not (if the detected gas concentration Gc is below the predetermined concentration), it may start the compressor 20.

[0065] <Another startup control> Figure 5 is a flowchart showing another startup control for the compressor 20. When the controller 50 receives a startup command for the compressor 20, it executes the control shown in Figure 5. Note that the internal temperature sensor 92 is not used in this control.

[0066] Steps S200 and S202 in Figure 5 are the same judgments as S100 and S102 in Figure 4, and steps S210 and S212 in Figure 5, which correspond to the results of those judgments, are the same processes as S110 and S112 in Figure 4. Therefore, the explanation of steps S200 and S202 in Figure 5 is omitted.

[0067] Step S204 is the process when No is determined in step S202. That is, step S204 is the process when the detected gas concentration Gc of the gas sensor 80 is greater than or equal to the first concentration and less than or equal to the second concentration. In step S204, the controller 50 uses the refrigerant saturated vapor pressure curve table 56 to obtain the refrigerant pressure corresponding to the detected temperature To of the external temperature sensor 82 as the expected pressure eP. The table 56 is stored in the storage device 54 in advance.

[0068] Figure 7 illustrates the saturated vapor pressure curve of a refrigerant. The saturated vapor pressure curve shows the relationship between the temperature and pressure of the refrigerant in the refrigerant circuit R when the refrigerant inside the refrigerant circuit R is in vapor-liquid equilibrium, that is, when the compressor 20 is not operating. In Figure 7, the refrigerant pressure corresponding to the temperature To detected by the external temperature sensor 82 is shown with the symbol Po (expected pressure eP). The controller 50 obtains the expected pressure eP(Po) corresponding to the external temperature To from the saturated vapor pressure curve table 56.

[0069] In step S206 of Figure 5, the controller 50 calculates a pressure threshold Pth by subtracting a predetermined pressure prP from the expected pressure eP. The predetermined pressure prP is stored in the memory device 54 beforehand.

[0070] Next, in step S208, the controller 50 checks whether the pressure Pi detected by the internal pressure sensor 94 is lower than the pressure threshold Pth calculated in step S206. If the pressure Pi detected by the internal pressure sensor 94 is lower than the pressure threshold Pth (step S208: Yes), the controller 50 proceeds to step S210. In step S210, the controller 50 does not start the compressor 20. That is, the controller 50 keeps the compressor 20 stopped.

[0071] Figure 7 shows an example of the relationship between "expected pressure eP", "detected pressure Pi of the internal pressure sensor 94", and "pressure threshold Pth" when the condition for step S208 in Figure 5 to be Yes is met.

[0072] On the other hand, in step S208 of Figure 5, if the detected pressure Pi of the internal pressure sensor 94 is greater than or equal to the pressure threshold Pth (step S208: No), the controller 50 proceeds to step S212. In step S212, the controller 50 starts the compressor 20.

[0073] In the other startup control described above, if the gas concentration detected by the gas sensor 80 is greater than or equal to the first concentration and less than or equal to the second concentration (step S202: No), the presence or absence of refrigerant leakage can be checked, and the startup of the compressor 20 can be avoided accordingly.

[0074] Before the compressor 20 starts up, the refrigerant inside the refrigerant circuit R is in vapor-liquid equilibrium, so the relationship between the temperature and pressure of the refrigerant inside the refrigerant circuit R follows the saturated vapor pressure curve of that refrigerant. Also, before the compressor 20 starts up, if there is no refrigerant leakage in the refrigerant circuit R, the internal temperature Ti and the external temperature To of the refrigerant circuit R will be the same or close to each other. Therefore, using the saturated vapor pressure curve described above, the internal pressure Pi of the refrigerant circuit R can be estimated from the external temperature To (estimated value of the internal temperature Ti of the refrigerant circuit R). This estimated internal pressure Pi is the expected pressure eP, and is the internal pressure Pi of the refrigerant circuit R when there is no refrigerant leakage in the refrigerant circuit R. On the other hand, if there is a refrigerant leak in the refrigerant circuit R, the internal pressure Pi of the refrigerant circuit R will be lower than the expected pressure eP. In the above-described startup control, the presence or absence of refrigerant leakage is checked using this principle. Specifically, according to the above startup control, if the detected pressure Pi of the internal pressure sensor 94 that detects the pressure inside the refrigerant circuit R is lower than the pressure threshold Pth obtained by subtracting a predetermined pressure prP from the expected pressure eP (step S208: Yes), it is determined that there is a possibility of refrigerant leakage, and the startup of the compressor 20 can be avoided (step S210).

[0075] <Control of the compressor during operation> Figure 6 is a flowchart showing the control of the compressor 20 during operation. The controller 50 may start the compressor 20 using the startup control shown in Figure 4 or Figure 5, or a general startup control, and then execute the control shown in Figure 6. The control shown in Figure 6 is executed repeatedly at a predetermined cycle.

[0076] In S300, the controller 50 checks whether the detected gas concentration Gc of the gas sensor 80 has increased and whether the rate of increase of the detected gas concentration Gc per unit time Gci has become higher than a predetermined rate of increase prGci. The unit time may be, for example, 1 second, 10 seconds, 30 seconds, 60 seconds, 120 seconds, 180 seconds, etc. The rate of increase Gci is the amount of increase in gas concentration G per unit time. The predetermined rate of increase prGci is stored in the memory device 54 in advance.

[0077] The controller 50 stops the compressor 20 if the rate of increase of the detected gas concentration Gc per unit time Gci becomes higher than a predetermined rate of increase prGci (step S300: Yes). On the other hand, the controller 50 maintains the operation of the compressor 20 if there is no increase in the detected gas concentration Gc, or if the rate of increase of the detected gas concentration Gc per unit time Gci is less than or equal to a predetermined rate of increase prGci (step S300: No).

[0078] This control system makes it possible to stop the compressor 20 before the refrigerant gas concentration inside the housing 60 becomes high when a refrigerant leak occurs in the refrigerant circuit R.

[0079] In another embodiment, the controller 50 may monitor the gas concentration Gc detected by the gas sensor 80 at predetermined intervals while the compressor 20 is operating, and stop the compressor 20 if the detected gas concentration Gc becomes higher than a predetermined concentration (for example, the second concentration described above). Otherwise (if the detected gas concentration Gc is below the predetermined concentration), the controller 50 may maintain the operation of the compressor 20. [Explanation of Symbols]

[0080] 12 Air conditioning unit, 20 Compressor, 22 Condenser, 24 Expansion valve, 26 Evaporator, 28 Receiver, 30 Heat exchanger, 32 Water pump, 34 Radiator, 40 Heat exchanger, 42 Water pump, 50 Controller, 52 Processor, 54 Memory device, 56 Table, 60 Enclosure, 60a Enclosure body, 60b Cover, 62 Hole, 64 Hose, 70 Air conditioning unit, 72 Cooler core, 74 Heater core, 75 Air passage, 76 Blower, 78 Air mix door, 80 Gas sensor, 82 External temperature sensor, 92 Internal temperature sensor, 94 Internal pressure sensor, 100 Plate, 102 Top surface, 104 Bottom surface, P1~P4 Ports, R Refrigerant circuit, RM Refrigerant module, C1 First coolant circuit, C2 Second coolant circuit, Wtr Airflow while driving, airflow from the WAC air conditioning.

Claims

1. In-vehicle air conditioning system, A refrigerant circuit through which a hydrocarbon refrigerant circulates has a compressor, a condenser for heat dissipation, an expansion valve, and an evaporator for heat absorption, The coolant heated by the condenser of the refrigerant circuit circulates to a first coolant circuit having a radiator, A second coolant circuit having a cooler core in which the coolant cooled by the evaporator of the refrigerant circuit circulates to cool the air conditioning air, A housing covering the refrigerant circuit, A gas sensor is disposed within the housing to detect the gas concentration of the refrigerant outside the refrigerant circuit, The system includes a controller for controlling the compressor, The aforementioned controller, When a command to start the compressor is received, if the gas concentration detected by the gas sensor is higher than a predetermined concentration, the compressor will not be started. In-vehicle air conditioner.

2. An in-vehicle air conditioning system according to claim 1, The aforementioned predetermined concentration is the second concentration. A first concentration lower than the second concentration is predetermined. The aforementioned controller, When a command to start the compressor is received, if the gas concentration detected by the gas sensor is lower than the first concentration, the compressor is started. In-vehicle air conditioner.

3. An in-vehicle air conditioning system according to claim 2, An internal temperature sensor for detecting the temperature inside the refrigerant circuit, The system includes an external temperature sensor that detects the temperature outside the refrigerant circuit, The aforementioned controller, When the compressor is started, if the gas concentration detected by the gas sensor is equal to or greater than the first concentration and equal to or less than the second concentration, If the temperature detected by the internal temperature sensor is lower than a temperature threshold obtained by subtracting a predetermined temperature from the temperature detected by the external temperature sensor, the compressor will not be started; otherwise, the compressor will be started. In-vehicle air conditioner.

4. An in-vehicle air conditioning system according to claim 2, An internal pressure sensor for detecting the pressure inside the refrigerant circuit, An external temperature sensor for detecting the temperature outside the refrigerant circuit, The system includes a storage device that stores a table representing the saturated vapor pressure curve of the refrigerant, The controller uses the saturated vapor pressure curve table to obtain the pressure of the refrigerant corresponding to the temperature detected by the external temperature sensor as the expected pressure. The aforementioned controller, When the compressor is started, if the gas concentration detected by the gas sensor is equal to or greater than the first concentration and equal to or less than the second concentration, If the pressure detected by the internal pressure sensor is lower than a pressure threshold obtained by subtracting a predetermined pressure from the expected pressure, the compressor will not be started; otherwise, the compressor will be started. In-vehicle air conditioner.

5. An in-vehicle air conditioning system according to any one of claims 1 to 4, The aforementioned controller, After starting the compressor, while the compressor is operating, When the gas concentration detected by the gas sensor increases and its rate of increase per unit time exceeds a predetermined rate of increase, the compressor is stopped. In-vehicle air conditioner.

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