Air conditioning device for vehicle

Abstract

Provided is a vehicle air-conditioning device capable of executing a hot-gas heating operation mode (FF control and FB control) without compromising the reliability of low-pressure-side components and the comfort of an occupant, even when the hot-gas heating operation mode is activated in an extremely low-temperature environment. In the vehicle air-conditioning device, a pressure reduction unit has a first pressure reduction unit provided downstream of an indoor heat exchange unit and a second pressure reduction unit provided in a hot-gas bypass, and a control device is capable of executing a hot-gas heating operation mode in which a part of a refrigerant compressed by a compressor flows to the indoor heat exchange unit and the remainder flows to the hot-gas bypass. When the hot-gas heating operation mode is started, if it is determined that the refrigerant pressure on the suction side of the compressor is a negative pressure, a pressure adjustment mode is executed in which the opening degrees of the first and second pressure reduction units are controlled to be equal to or greater than a predetermined opening degree and the refrigerant pressure on the suction side of the compressor is increased.

Description

Technical Field

[0001] This invention relates to an automotive air conditioning device. Background Technology

[0002] In electric vehicles (EVs) that do not have a heat source from a combustion system such as an engine, or in automotive air conditioning systems where the heat from the combustion system is relatively low, heat pump-based air conditioning systems are typically used. During normal heating operation, this type of air conditioning system absorbs heat from the outside air in the outdoor heat exchanger, which acts as a heat absorber, and then heats the air supplied to the vehicle interior in the heat exchanger of the air conditioning unit (indoor air conditioning system), which acts as a radiator. Therefore, during normal heating operation, when the outside temperature becomes extremely low, heat absorption from the outside air becomes difficult, and the heating capacity decreases.

[0003] In contrast, the hot gas heating operation mode, by executing a cycle in which the high-temperature, high-pressure refrigerant discharged from the heat pump compressor flows through the heat exchange section of the air conditioning unit, and is then depressurized and drawn into the compressor without passing through the outdoor heat exchange section, can operate in a low-temperature external gas environment where heat absorption is difficult to achieve in the outdoor heat exchange section. In this hot gas heating operation mode, a bypass refrigerant flow path (hot gas bypass) is provided in the refrigerant circuit, in which a portion of the high-temperature, high-pressure refrigerant discharged from the compressor is depressurized and returned to the compressor without passing through the heat exchanger of the air conditioning unit. By directing a portion of the refrigerant compressed in the compressor to the heat exchange section of the air conditioning unit and the remaining portion to the hot gas bypass, the amount of heat input and heat dissipation during operation can be regulated (see Patent Document 1 below).

[0004] Existing technical documents

[0005] Patent documents

[0006] Patent Document 1: Japanese Patent Application Publication No. 2023-46604 Summary of the Invention

[0007] The technical problem that the invention aims to solve

[0008] However, in conventional automotive air conditioning systems, when the refrigerant temperature is low (e.g., below -30°C) or in extremely low-temperature environments such as below -40°C, the refrigerant saturation pressure easily becomes negative. When starting the hot air heating mode under these conditions, the time it takes for the refrigerant pressure drawn into the compressor (low-pressure side refrigerant pressure) to become negative increases. This can potentially damage the reliability of components on the low-pressure side (such as the compressor). Furthermore, in such extremely low-temperature environments (e.g., below -40°C), the time to reach the target outlet temperature increases, resulting in insufficient instant heating and potentially compromising passenger comfort.

[0009] The present invention was made in view of the following situation. That is, the technical problem of the present invention is to provide an automotive air conditioning device that, even when the hot air heating operation mode is activated in extremely low temperature environments (e.g., below -40°C), will not damage the reliability of low-pressure side components (compressor, etc.) and the comfort of occupants, and can perform hot air heating operation modes (feedforward control (FF control) and feedback control (FB control), etc.).

[0010] Technical solutions adopted to solve technical problems

[0011] To address this technical problem, the present invention includes the following structure.

[0012] A vehicle air conditioning system includes: a refrigerant circuit having a compressor, an indoor heat exchange section, an external heat exchange section, a pressure reducing section, and a hot gas bypass, wherein the hot gas bypass allows at least a portion of the refrigerant compressed in the compressor to be depressurized and returned to the compressor without passing through the indoor heat exchange section and the external heat exchange section; and a control device that controls the refrigerant circuit, wherein the pressure reducing section includes: a first pressure reducing section disposed downstream of the indoor heat exchange section; and a second pressure reducing section disposed in the hot gas bypass, wherein the control device is capable of executing a hot gas heating operation mode in which a portion of the refrigerant compressed by the compressor flows to the indoor heat exchange section and the remaining portion flows to the hot gas bypass, and when the hot gas heating operation mode is activated, if it is determined that the refrigerant pressure on the suction side of the compressor is negative, then a pressure regulation mode is executed in which the opening degree of the first pressure reducing section and the second pressure reducing section is controlled to a predetermined opening degree or higher and the refrigerant pressure on the suction side of the compressor is increased.

[0013] Invention Effects

[0014] According to the present invention, an automotive air conditioning device having such features, even when the hot air heating operation mode is activated in extremely low temperature environments (e.g., below -40°C), the hot air heating operation mode (FF control and FB control) can be executed without compromising the reliability of low-pressure side components (compressor, etc.) and the comfort of occupants. Attached Figure Description

[0015] Figure 1 This is an explanatory diagram showing a structural example of an automotive air conditioning device according to an embodiment of the present invention.

[0016] Figure 2 This is an explanatory diagram showing the control device of a vehicle air conditioning system.

[0017] Figure 3 This is an explanatory diagram showing the hardware structure of the control device for an air conditioning system installed in an electric vehicle (EV).

[0018] Figure 4 This is an explanatory diagram illustrating the operation of the refrigerant circuit in the hot air heating mode of an automotive air conditioning system according to an embodiment of the present invention.

[0019] Figure 5 This is an explanatory diagram (flowchart) showing the processing content of the start-up control process for the hot gas heating operation mode.

[0020] Figure 6 This is an explanatory diagram (flowchart) showing the processing content of the pressure regulation mode.

[0021] Figure 7 This is an illustration (curve graph) of the following behaviors in pressure regulation mode: compressor speed [rpm / 100] (NC / 100 [rpm]) (curve a), opening degree of the second pressure reducing section (EXV_bps) [%] (EXC [%]) (curve b), opening degree of the third pressure reducing section (EXV_chi) [%] (EXC [%]) (curve c), suction refrigerant pressure Ps [bar] (curve d), outlet refrigerant pressure Pci [bar] (curve e), outlet refrigerant temperature Tci (ICND Outlet Temp) [°C] (curve f), air volume of the blower (Air Flow / 10) [kg / h] (curve g), and heating capacity (Heat Capacity) [KW] (curve h). Detailed Implementation

[0022] Hereinafter, embodiments of the present invention (this embodiment) will be described with reference to the accompanying drawings. In the following description, the same symbols in different figures denote parts with the same function, and repeated descriptions in each figure are omitted as appropriate.

[0023] [Structure of refrigerant circuits, etc., in automotive air conditioning systems]

[0024] Figure 1 An example of the structure of the vehicle air conditioning unit 1 according to this embodiment is shown. The example shown here is just one example and is not particularly limited to a specific structure.

[0025] The vehicle air conditioning unit 1 includes a refrigerant circuit 10 and an air conditioning unit (vehicle interior air conditioning unit) 20. The refrigerant circuit 10 has a refrigerant flow path that depressurizes the refrigerant discharged from the compressor 2 and returns it to the compressor 2. The compressor 2, indoor heat exchange sections 21 and 22 disposed inside the air conditioning unit 20, and an outdoor heat exchange section (external heat exchange section) 11 disposed outside the vehicle are arranged along the refrigerant flow path. The indoor heat exchange sections 21 and 22 are configured for heat exchange between the air flowing inside the air conditioning unit 20 and the refrigerant, while the outdoor heat exchange section 11 is configured for heat exchange between external air and the refrigerant outside the vehicle. For example, the indoor heat exchange section 21 is used to heat the air, and the indoor heat exchange section 22 is used to cool the air. Downstream of the indoor heat exchange section 21 in the refrigerant flow path, a refrigerant temperature sensor 43A is provided to detect the outlet refrigerant temperature (high-pressure side refrigerant temperature) Tci discharged from the indoor heat exchange section 21, and a refrigerant pressure sensor 44B is provided to detect the outlet refrigerant pressure (high-pressure side refrigerant pressure) Pci discharged from the indoor heat exchange section 21.

[0026] Compressor 2 compresses the refrigerant and circulates it within refrigerant circuit 10. The refrigerant, after compression in compressor 2, is depressurized to the desired pressure via a suitably selected refrigerant flow path, for example, selectively via expansion valves, a first pressure reducing section V1, a second pressure reducing section V2 (second pressure reducing section), a third pressure reducing section V3 (first pressure reducing section), and a fourth pressure reducing section V4. Flow path switching valves 12 and 13 for switching the refrigerant flow path and check valves 14 and 15 for restricting the direction of refrigerant flow are provided in refrigerant circuit 10. A storage tank 16 is provided upstream of compressor 2 in refrigerant circuit 10 to recover liquid refrigerant and separate refrigerant gas and liquid. A refrigerant pressure sensor 44A is provided between storage tank 16 and compressor 2 to detect the suction refrigerant pressure (low-pressure side refrigerant pressure) Ps drawn into compressor 2.

[0027] As described above, the air conditioning unit 20 includes indoor heat exchange sections 21 and 22. Air drawn in from indoors or outdoors by the blower 23 is conditioned by passing through the indoor heat exchange sections 21 and 22 before being blown into the room. An air baffle 24 is provided in the air conditioning unit 20. Figure 1 When the air baffle 24 shown is fully open, the air introduced by the blower 23 passes through the indoor heat exchange sections 21 and 22 and is blown out into the room.

[0028] Furthermore, when the air baffle 24 is fully closed, the inflow side of the indoor heat exchange section 21 is sealed, and the air introduced by the blower 23 only passes through the indoor heat exchange section 22 and is blown out into the room. Another air baffle 25 provided in the air conditioning unit 20 switches the air introduced into the blower 23 between the indoor and outdoor environments. The air baffle 25 can selectively close the air inlet 25A connected to the outside and the air inlet 25B connected to the inside, and draw air in from one of them. Alternatively, by placing the air baffle 25 in an intermediate position, air can be drawn in from both the air inlet 25A and the air inlet 25B.

[0029] Furthermore, although examples of direct heat exchange between the refrigerant and air have been described for the outdoor heat exchange section (external heat exchange section) 11 and the indoor heat exchange sections 21 and 22, indirect heat exchange between the refrigerant and air can also be achieved through a heat carrier after heat exchange with the refrigerant. That is, it can also be configured such that the refrigerant absorbs heat from the air through the heat carrier, or that the refrigerant dissipates heat to the air through the heat carrier.

[0030] like Figure 1 As shown, the vehicle air conditioning unit 1 includes a heat carrier circuit 30 for temperature regulation of on-board equipment. The heat carrier circuit 30 circulates the heat carrier via a circulation pump 31, and heats the heat carrier in a heater (ECH: Electric Coolant Heater) 32, or recovers waste heat from on-board equipment (temperature-regulated objects) such as a battery in a temperature-regulated object heat exchange section 33. Furthermore, in both the refrigerant circuit 10 and the heat carrier circuit 30, a refrigerant heat carrier heat exchange section 34 is provided, where heat exchange between the refrigerant and the heat carrier occurs in the refrigerant flow path 34A and the heat carrier flow path 34B, serving as a heat exchange section for temperature regulation of the on-board equipment. Such a heat carrier circuit 30 is provided as needed.

[0031] [Control Device]

[0032] Vehicle air conditioning unit 1 includes Figure 2The control device (air conditioning ECU) 100 shown. The control device 100 controls the refrigerant circuit 10 and the air conditioning unit 20 based on various input signals 60 (air conditioning indicator signal, charger connection signal, etc.) including user setting information and information from the vehicle, and detection signals from the sensor unit 40, and controls the heat transfer circuit 30 as needed.

[0033] The sensor unit 40 that inputs detection signals to the control device 100 includes, for example, an external gas sensor 41 that detects the external gas state such as external gas temperature and external gas humidity; a compressor current sensor 42 that detects the power consumption (energy consumption) of the compressor 2; a refrigerant temperature sensor 43 and a refrigerant pressure sensor 44 that detect the state of the refrigerant; and an air supply temperature sensor 45 that detects the air supply temperature of the air conditioning unit 20.

[0034] The refrigerant temperature sensor 43 includes a refrigerant temperature sensor 43A (refer to) that detects the outlet refrigerant temperature (high-pressure side refrigerant temperature) Tci discharged from the indoor heat exchange section 21. Figure 1 The refrigerant pressure sensor 44 includes: a refrigerant pressure sensor 44A that detects the suction refrigerant pressure (low-pressure side refrigerant pressure) Ps drawn into the compressor 2; and a refrigerant pressure sensor 44B that detects the outlet refrigerant pressure (high-pressure side refrigerant pressure) Pci of the indoor heat exchange section 21 (see reference). Figure 1 Additionally, the refrigerant pressure sensor 44 may also include a refrigerant pressure sensor (not shown) that detects the discharge refrigerant pressure (high-pressure side refrigerant pressure) Pd discharged from the compressor 2. These sensors are one example; the sensor unit 40 includes various sensors that detect information required for various controls of the control device 100.

[0035] The controlled objects of the control device 100 are, in the refrigerant circuit 10, compressor 2, first pressure reducing unit V1, second pressure reducing unit V2 (second pressure reducing unit), third pressure reducing unit V3 (first pressure reducing unit), fourth pressure reducing unit V4, flow path switching valves 12 and 13, etc.; in the air conditioning unit 20, blower 23, air baffles 24 and 25, etc.; and in the heat transfer circuit 30, circulation pump 31, etc. In the vehicle air conditioning unit 1, the control device 100 can switch and execute an external gas heat absorption heating mode and a hot gas heating mode. In the external gas heat absorption heating mode, the external gas absorbs heat in the outdoor heat exchange unit 11. In the hot gas heating mode, the external gas does not absorb heat in the outdoor heat exchange unit 11, but rather the high-temperature refrigerant compressed in the compressor 2 dissipates heat in the indoor heat exchange unit 21 to heat the vehicle interior.

[0036] [Structure of the control unit in an electric vehicle (EV)]

[0037] like Figure 3 As shown, the control device (air conditioning ECU) 100 included in the vehicle air conditioning system 1 is configured as an ECU connected to various ECUs (Electronic Control Units) that control the electric vehicle (EV) via the vehicle network L. The control device 100 includes a CPU (Central Processing Unit) 101, a ROM (Read Only Memory) 102, a RAM (Random Access Memory) 103, an input / output I / F (Interface) 104, an in-vehicle communication I / F (Interface) 105, etc., and all hardware is interconnected via a bus 106.

[0038] CPU 101 executes various programs stored in ROM 102 to control the control device 100. ROM 102 is non-volatile memory. For example, ROM 102 stores programs executed by CPU 101, data required by CPU 101 to execute programs, etc. RAM 103 is a main storage device such as DRAM (Dynamic Random Access Memory) or SRAM (Static Random Access Memory).

[0039] For example, RAM 103 functions as a working area used when the CPU 101 executes a program. Input / output I / O 104 connects to various sensors or monitors installed in the EV, inputting data to the CPU 101 and outputting data processed by the CPU 101. In-vehicle communication I / O 105 connects to the vehicle network L to control data transmission and reception with other ECUs installed in the EV.

[0040] The control device 100 receives data related to the surrounding environment or the operating status of the EV via input / output I / F 104 or in-vehicle communication I / F 105, and executes the control of the vehicle air conditioning device 1 by the program executed by the CPU 101.

[0041] A battery B is installed in the EV. The battery B is charged by connecting the charger plug PS to the battery plug BP, and the battery B supplies power to the vehicle air conditioning unit 1. When the battery plug BP and plug PS are connected, a charger connection signal is sent to the control device 100 via the vehicle network L.

[0042] [External gas heat absorption and heating operation mode]

[0043] The operation of refrigerant circuit 10 in external gas heat absorption and heating mode Figure 1 In the refrigerant circuit 10 shown, the second pressure reducing unit V2, the third pressure reducing unit V3, the fourth pressure reducing unit V4, and the flow path switching valve 12 are all closed. On the other hand, the flow path switching valve 13 is open, and the first pressure reducing unit V1 is open.

[0044] In the external gas heat absorption and heating operation mode, the high-temperature, high-pressure refrigerant discharged from the compressor 2 passes through the indoor heat exchange section 21 within the air conditioning unit 20, where it is depressurized in the first pressure reduction section V1. The low-pressure refrigerant then passes through the outdoor heat exchange section 11, and returns to the compressor 2 via the flow path switching valve 13, check valve 14, and storage tank 16. At this time, the following cycle occurs: the high-pressure refrigerant discharged from the compressor 2 condenses and dissipates heat in the indoor heat exchange section 21, is depressurized in the first pressure reduction section V1 and becomes low-pressure refrigerant, absorbs heat and evaporates in the outdoor heat exchange section 11, and returns to the compressor 2. Furthermore, in the air conditioning unit 20, the air introduced by the blower 23 is heated by the heat dissipation of the indoor heat exchange section 21 and blown into the vehicle interior.

[0045] [Refrigerant circuit operation in hot gas heating mode]

[0046] In the hot air heating operation mode, the refrigerant does not absorb heat in the outdoor heat exchange section 11. Instead, part or all of the refrigerant compressed in the compressor 2 dissipates heat in the indoor heat exchange section 21 to heat the vehicle interior. Figure 4 The operation of refrigerant circuit 10 in hot gas heating mode is explained below. In the diagram of refrigerant circuit 10, the thick black lines represent the refrigerant flow path for high-pressure refrigerant, and the blank lines represent the refrigerant flow path for refrigerant after pressure reduction. Additionally, the dashed lines in refrigerant circuit 10 represent refrigerant flow paths where refrigerant is not flowing, and the dashed lines in heat carrier circuit 30 represent the cessation of heat carrier flow.

[0047] exist Figure 4 In the refrigerant circuit 10, a portion of the high-temperature, high-pressure refrigerant discharged from compressor 2 passes through indoor heat exchange section 21 and flow path switching valve 12, and is depressurized in the third pressure reducing section V3 (first pressure reducing section) to become low-pressure refrigerant. It then passes through refrigerant heat carrier heat exchange section 34, undergoes gas-liquid separation in storage tank 16, and returns to compressor 2. At this time, in refrigerant circuit 10, by setting the first pressure reducing section V1 to be fully closed, refrigerant is prevented from flowing through outdoor heat exchange section 11. Furthermore, by setting the fourth pressure reducing section V4 to be fully closed, refrigerant is prevented from flowing through indoor heat exchange section 22.

[0048] The refrigerant circuit 10 has a hot gas bypass 10V that allows at least a portion of the refrigerant compressed in the compressor 2 to be depressurized and returned to the compressor 2 without passing through the indoor heat exchange section 21 and the outdoor heat exchange section 11, and includes a refrigerant flow path capable of performing a hot gas heating operation mode. In the hot gas bypass 10V, a portion of the high-temperature, high-pressure refrigerant branches off at a bifurcation point P1 immediately downstream of the compressor 2, is depressurized in the second depressurization section V2 (second depressurization section), and merges with the low-pressure refrigerant depressurized in the third depressurization section V3 at a confluence point P2 immediately upstream of the storage tank 16.

[0049] By setting up such a hot gas bypass 10V, in the hot gas heating operation mode, the gaseous refrigerant passing through the hot gas bypass 10V can mix with the liquid refrigerant condensed due to heat dissipation in the indoor heat exchange section 21, and return to the compressor 2 after becoming a gas-rich refrigerant. Furthermore, by increasing the refrigerant flow rate through the hot gas bypass 10V, the heat dissipation in the indoor heat exchange section 21 can be suppressed. The refrigerant flow rate through the hot gas bypass 10V is regulated by opening and closing the second pressure reducing section V2, maintaining a balance between the heat dissipation of the refrigerant circuit 10 and the heat input to the compressor 2. That is, the second pressure reducing section V2 functions as a flow regulating section that adjusts the flow rate of the refrigerant flowing through the hot gas bypass 10V.

[0050] In the hot air heating operation mode, the refrigerant flow is depressurized by the third depressurization section V3 in the flow path via the indoor heat exchange section 21. Therefore, the upstream side becomes high-pressure refrigerant, and the downstream side becomes low-pressure refrigerant. At this time, it is important to maintain the heating capacity by not performing heat exchange in the refrigerant heat carrier heat exchange section 34 in the low-pressure side flow path. Moreover, in the air conditioning unit 20, the air introduced by the blower 23 is heated by the heat dissipation in the indoor heat exchange section 21 and blown into the vehicle interior.

[0051] [Hot Gas Heating Operation Mode Start-up Control Process]

[0052] However, when starting the hot air heating mode in extremely low temperature environments (e.g., below -40°C), the refrigerant pressure Ps is prone to become a negative pressure (e.g., less than 1.2 bar abs) lower than atmospheric pressure. Therefore, in the vehicle air conditioning unit 1, when the refrigerant pressure Ps is negative when starting the hot air heating mode, a pressure regulation mode is executed to improve this negative pressure state. Figure 6 Then, the hot gas heating operation mode is executed.

[0053] Specifically, when the vehicle air conditioning unit 1 starts the hot air heating operation mode, the control device 100 performs... Figure 5The control device 100 initiates the hot gas heating operation mode startup control process. When starting the hot gas heating operation mode, if... Figure 5 The series of processes shown includes step S1, in which a determination is made as to whether the intake refrigerant pressure (low-pressure side refrigerant pressure) Ps detected by the refrigerant pressure sensor 44A is a negative pressure lower than atmospheric pressure.

[0054] When the control device 100 determines that the intake refrigerant pressure Ps is negative ("Yes" in step S1), it executes the pressure regulation mode in the next step S2. Figure 6 Then, in step S3, the hot gas heating operation mode is executed (feedforward control (FF control) and feedback control (FB control). On the other hand, when it is determined that the intake refrigerant pressure Ps is not negative (i.e., positive pressure) ("No" in step S1), the control device 100 does not execute the pressure regulation mode of step S2 ( Figure 6 Instead of executing the hot gas heating operation mode (FF control and FB control) in the next step S3, the control device 100 terminates the process after executing the hot gas heating operation mode (FF control and FB control) in step S3. Figure 5 The series of processes shown.

[0055] Here, use Figure 6 The processing of the pressure regulation mode in step S2 performed by the control device 100 will be explained. When the control device 100 starts executing the pressure regulation mode, in step S21, it sets the speed of the compressor 2 to a high speed and controls the compressor 2 to start at this high speed (i.e., high speed). This high speed is only required to increase the suction refrigerant pressure (low-pressure side refrigerant pressure) Ps drawn into the compressor 2. For example, it can be the maximum speed (i.e., maximum speed) of the compressor 2, but it can also be other speeds, such as 80 to 90% of the maximum speed.

[0056] When starting the hot air heating mode with a negative refrigerant pressure Ps, as in conventional automotive air conditioning systems, if the opening of the second pressure reducing section V2 and the third pressure reducing section V3 is reduced from the start of startup, the time during which the refrigerant pressure Ps remains negative becomes longer. In such automotive air conditioning systems, the reliability of low-pressure side components (such as compressors) may be compromised, and the comfort of occupants may be compromised due to the inability to achieve immediate heating. Therefore, in automotive air conditioning system 1, in step S22 after step S21, the control device 100 controls the second pressure reducing section V2 and the third pressure reducing section V3 so that the opening of both the second pressure reducing section V2 (second pressure reducing section) and the third pressure reducing section V3 (first pressure reducing section) is at or above a high opening degree, i.e., a predetermined opening degree.

[0057] Thus, by controlling the control device 100, while starting the compressor 2 at high speed (i.e., high speed), by setting the opening degree of the second pressure reducing section V2 and the third pressure reducing section V3 to a predetermined opening degree or higher, the suction refrigerant pressure Ps can be increased and the time when the suction refrigerant pressure Ps is negative pressure can be shortened.

[0058] The term "above the specified opening" here can be, for example, a high opening of more than 80% of the maximum opening of the second pressure reducing section V2 and the third pressure reducing section V3. As a more specific example, it can be the maximum opening of the second pressure reducing section V2 and the third pressure reducing section V3 (100%).

[0059] Furthermore, for example, in step S22, when the control device 100 controls the second pressure reducing section V2 and the third pressure reducing section V3 to a high opening degree (i.e., a predetermined opening degree or higher), it can also control the second pressure reducing section V2 and the third pressure reducing section V3 so that the opening degree of the third pressure reducing section V3 is greater than or equal to the opening degree of the second pressure reducing section V2. In this case, even if the refrigerant flow path (piping) used in the hot gas heating operation mode is overcooled in an extremely low temperature environment (e.g., below -40°C), the refrigerant flow path can be heated by allowing the refrigerant to flow through the entire refrigerant flow path. Therefore, excessive reduction in the refrigerant temperature and refrigerant pressure on the low-temperature side can be prevented. That is, in this case, the suction refrigerant pressure Ps can be effectively increased and the negative pressure state of the suction refrigerant pressure Ps can be improved.

[0060] In step S23, following step S22, the control device 100 determines whether the suction refrigerant pressure (low-pressure side refrigerant pressure) Ps detected by the refrigerant pressure sensor 44A is positive (e.g., 1.2 bar abs or higher). If the control device 100 determines that the suction refrigerant pressure Ps is positive ("Yes" in step S23), the process proceeds to step S24. Alternatively, the control device 100 may determine that the suction refrigerant pressure Ps is positive ("Yes" in step S23) at a specific pressure value within a specific range that includes a lower limit of positive pressure (set as "specific pressure").

[0061] On the other hand, when the control device 100 determines that the suction refrigerant pressure Ps detected by the refrigerant pressure sensor 44A is not positive ("No" in step S23), it performs the process of step S23 again. That is, the control device 100 repeatedly performs the process of step S23 before determining that the suction refrigerant pressure Ps is positive.

[0062] In the vehicle air conditioning unit 1, after the control device 100 performs the above-mentioned process (negative pressure improvement process) to improve the negative pressure state of the intake refrigerant pressure Ps in the pressure regulation mode, as a preprocessing step for the hot gas heating operation mode (FF control and FB control), the FF control and FB control can be stably performed by performing the process of steps S24 to S30.

[0063] In step S24 following step S23, since the intake refrigerant pressure Ps is positive, the control device 100 controls the opening degree of both the second pressure reducing section V2 (second pressure reducing section) and the third pressure reducing section V3 (first pressure reducing section) to a low opening degree.

[0064] The “low opening” here refers to an opening that is smaller than the current “prescribed opening” of the second pressure relief section V2 (second pressure relief section) and the third pressure relief section V3 (first pressure relief section). For example, it can be 3% to 10% of the maximum opening of the second pressure relief section V2 and the third pressure relief section V3, but it is not limited to this and can also be other openings.

[0065] In this way, by using the control device 100 to control the opening degree of the second pressure reducing section V2 and the third pressure reducing section V3 to a low opening degree, a pressure difference can be generated between the high-pressure side refrigerant pressure and the low-pressure side refrigerant pressure in the refrigerant circuit 10, and the excessive rise of the high-pressure side refrigerant pressure and the high-pressure side refrigerant temperature can also be suppressed.

[0066] In step S25, following step S24, the control device 100 determines whether the outlet refrigerant temperature (high-pressure side refrigerant temperature) Tci emitted from the indoor heat exchange section 21, detected by the refrigerant temperature sensor 43A, is above the temperature threshold Tm. If the control device 100 determines that the outlet refrigerant temperature (high-pressure side refrigerant temperature) Tci is above the threshold Tm ("Yes" in step S25), the process proceeds to step S26.

[0067] On the other hand, when the control device 100 determines that the outlet refrigerant temperature Tci detected by the refrigerant temperature sensor 43A and discharged from the indoor heat exchange section 21 is not above the threshold Tm (i.e., less than the threshold Tm) (in step S25, it is "No"), it performs the processing of step S25 again. That is, the control device 100 repeatedly performs the processing of step S25 before determining that the outlet refrigerant temperature Tci is above the threshold Tm.

[0068] Alternatively, in step S25, the control device 100 may perform a judgment process using an alternative value instead of the aforementioned determination process based on the outlet refrigerant temperature Tci. This alternative value may be a value detected for the high-pressure side refrigerant.

[0069] For example, in step S25, the control device 100 can also replace the above-mentioned determination process of outlet refrigerant temperature Tci by determining whether the outlet refrigerant pressure (high-pressure side refrigerant pressure) Pci discharged from the indoor heat exchange section 21 detected by the refrigerant pressure sensor 44B is above the first threshold Pm1. If it is determined that the outlet refrigerant pressure Pci is above the first threshold Pm1 ("Yes" in step S25), the process proceeds to step S26. If it is determined that the outlet refrigerant pressure Pci is not above the first threshold Pm1 ("No" in step S25), the process of step S25 is performed again.

[0070] Alternatively, for example, in step S25, the control device 100 may replace the above-described determination process of the outlet refrigerant temperature Tci with a determination process of the discharge refrigerant pressure (high-pressure side refrigerant pressure) Pd detected by a refrigerant pressure sensor (not shown) located immediately downstream (discharge side) of the compressor 2. In this case, in step S25, the control device 100 determines whether the discharge refrigerant pressure Pd is above the second threshold Pm2. If it determines that the discharge refrigerant pressure Pd is above the second threshold Pm2 ("Yes" in step S25), the process proceeds to step S26. If it determines that the discharge refrigerant pressure Pd is not above the second threshold Pm2 ("No" in step S25), the process of step S25 is performed again.

[0071] In step S26, following step S25, the control device 100 controls the blower 23 to operate at its minimum airflow. By operating the blower 23, excessive rises in the high-pressure side refrigerant pressure and temperature can be suppressed, and by setting the airflow to the minimum, excessive drops in the high-pressure side refrigerant pressure and temperature can also be suppressed. Therefore, the temperature threshold Tm (or the first pressure threshold Pm1 and the second pressure threshold Pm2) in step S25 is not particularly limited, as long as it is an appropriate value for the high-pressure side refrigerant temperature (or high-pressure side refrigerant pressure) when the blower 23 operates at the minimum airflow in step S26.

[0072] In step S27, following step S26, the control device 100 increases the opening of the second pressure reducing section V2, thereby increasing the intake refrigerant pressure Ps.

[0073] In step S28, following step S27, the control device 100 determines whether the suction refrigerant pressure (low-pressure side refrigerant pressure) Ps detected by the refrigerant pressure sensor 44A has increased by a predetermined amount ΔP (arbitrary value). If the control device 100 determines that the suction refrigerant pressure Ps has increased by the predetermined amount ΔP ("yes" in step S28), the process proceeds to step S29.

[0074] On the other hand, when the control device 100 determines that the intake refrigerant pressure Ps detected by the refrigerant pressure sensor 44A has not increased by a predetermined amount ΔP ("No" in step S28), it performs the process of step S28 again. That is, the control device 100 repeatedly performs the process of step S28 before the intake refrigerant pressure Ps increases by a predetermined amount ΔP.

[0075] In step S29 following step S28, the control device 100 determines whether the suction refrigerant pressure (low-pressure side refrigerant pressure) Ps detected by the refrigerant pressure sensor 44A is equal to the target value PSO of the low-pressure side refrigerant pressure. When the control device 100 determines that the suction refrigerant pressure (low-pressure side refrigerant pressure) Ps is equal to the target value PSO ("Yes" in step S29), the process ends. Figure 6 The pressure regulation mode shown is a series of processes, and the process is advanced to... Figure 5 Step S3 (Hot gas heating operation mode). In addition, "the intake refrigerant pressure Ps is the target value PSO" here includes not only the case where the intake refrigerant pressure Ps is exactly the same as the target value PSO, but also the case where the intake refrigerant pressure Ps is a value close to the target value PSO.

[0076] On the other hand, when the control device 100 determines that the intake refrigerant pressure (low-pressure side refrigerant pressure) Ps has not reached the target value PSO ("No" in step S29), it increases the airflow of the blower 23 in the next step S30, and then returns to the process of step S27 to control the process by increasing the opening of the second pressure reducing section V2 again. That is, the processes of steps S27 to S30 performed by the control device 100 are repeated until the intake refrigerant pressure Ps reaches the target value PSO.

[0077] In this way, the control device 100 increases the opening degree of the second pressure reducing section V2, thereby increasing the suction refrigerant pressure (low-pressure side refrigerant pressure) Ps by a predetermined amount ΔP. While the target value PSO of the low-pressure side refrigerant pressure has not been reached, the control device 100 increases the airflow of the blower 23 (step S30). This increases the heat dissipation in the indoor heat exchange section 21 while further increasing the opening degree of the second pressure reducing section V2 (step S27). Thus, the control device 100 achieves a balance between the heat dissipation of the refrigerant circuit 10 and the heat input to the compressor 2, while simultaneously ensuring that the suction refrigerant pressure Ps reaches the target value PSO.

[0078] Figure 7 An example of the behavior of various values ​​under pressure regulation mode is shown. That is, in Figure 7 In the example, curve a (solid line) is the speed of compressor 2 (Compressor Speed) [rpm / 100] (NC / 100 [rpm]), curve b (short dashed line) is the opening degree of the second pressure reducing section V2 (EXV_bps) [%] (EXC [%]), and curve c (long dashed line) is the opening degree of the third pressure reducing section V3 (EXV_chi) [%] (EXC [%]).

[0079] Additionally, curve d (solid line) represents the suction refrigerant pressure Ps [bar] drawn into compressor 2, and curve e (solid line) represents the outlet refrigerant pressure Pci [bar] discharged from indoor heat exchange section 21. Furthermore, curve f (solid line) represents the outlet refrigerant temperature Tci [°C] discharged from indoor heat exchange section 21, curve g (solid line) represents the airflow of fan 23 (Air Flow / 10) [kg / h], and curve h (solid line) represents the heating capacity [kW].

[0080] In Figure 7 In the example, since the intake refrigerant pressure Ps [bar] (curve d) is less than atmospheric pressure (1.2 barabs), the control device 100 determines that the intake refrigerant pressure Ps is negative ("yes" in step S1 above). Therefore, the control device 100 begins to execute the pressure regulation mode (step S2 above). At its start (at the start of period A), the control device 100 sets the compressor 2 speed [rpm / 100] (curve a) to the maximum speed (i.e., maximum rotational speed 10000 rpm) and controls it to start at this maximum speed. Afterward, it controls the compressor 2 to always operate at a constant maximum speed in the pressure regulation mode (periods A to E) (step S21 above).

[0081] Meanwhile, during period A, the control device 100 always controls the opening degree (EXV_bps) [%] (curve b) of the second pressure reducing unit V2 and the opening degree (EXV_chi) [%] (curve c) of the third pressure reducing unit V3 to the maximum opening degree (100%) as an example of "above the specified opening degree" (step S22 above).

[0082] Then, when the intake refrigerant pressure Ps [bar] (curve d) rises and reaches atmospheric pressure (1.2 bar abs), the control device 100 determines that the intake refrigerant pressure Ps is positive ("yes" in step S23 above), and performs processing after period B as pre-processing for stably executing the subsequent hot gas heating operation mode (FF control and FB control). At the beginning of period B, the control device 100 controls the opening degree (EXV_bps) [%] (curve b) of the second pressure reducing unit V2 to 5.4%, which is a low opening degree, and controls the opening degree (EXV_chi) [%] (curve c) of the third pressure reducing unit V3 to 3.2%, which is a low opening degree (step S24 above). In addition, the opening degree (EXV_chi) [%] (curve c) of the third pressure reducing unit V3 is always controlled at the above 3.2% (periods B to E) thereafter.

[0083] Through the control of such a control device 100, during period B, a pressure difference is generated between the intake refrigerant pressure (low-pressure side refrigerant pressure) Ps (curve d) and the outlet refrigerant pressure Pci [bar] (curve e) of the indoor heat exchange section 21. At the same time, excessive rises in the outlet refrigerant pressure Pci [bar] (curve e) and the outlet temperature Tci [°C] (curve f) of the indoor heat exchange section 21 are also suppressed.

[0084] Moreover, in Figure 7 In the example, during period B, when the outlet refrigerant temperature Tci (ICND Outlet Temp) [°C] (curve f) discharged from the indoor heat exchange section 21 rises and reaches the temperature threshold Tm ("Yes" in step S25 above), the control device 100 sets the airflow (Air Flow / 10) [kg / h] (curve g) of the blower 23 to the minimum airflow during period C, and controls the blower 23 to operate at this minimum airflow (step S26 above). During period C, by operating the blower 23 at the minimum airflow (curve g), excessive rises in the outlet refrigerant pressure Pci [bar] (high-pressure side refrigerant pressure) of curve e and the outlet refrigerant temperature Tci [°C] (high-pressure side refrigerant temperature) of curve f are suppressed, as are excessive drops in their values.

[0085] During period C, a necessary pressure difference is generated between the outlet refrigerant pressure Pci [bar] (curve e) and the suction refrigerant pressure Ps [bar] (curve d) at the high-pressure and low-pressure sides of the refrigerant circuit 10. In this state, during the following period D, the control device 100 increases the opening degree (EXV_bps) [%] (curve b) of the second pressure reducing section V2 (step S27 above). Therefore, during period D, as the opening degree (EXV_bps) [%] (curve b) of the second pressure reducing section V2 increases, the suction refrigerant pressure Ps [bar] (curve d) also rises.

[0086] Moreover, in Figure 7 In the example, the control device 100 determines that the intake refrigerant pressure Ps [bar] (curve d) has increased by a predetermined amount ΔP ("Yes" in step S28 above) but has not yet reached the target value PSO of the low-pressure side refrigerant pressure ("No" in step S29 above). Therefore, during the initial period E, the airflow (Air Flow / 10) [bar] (curve g) of the blower 23 is further increased (step S30 above). Additionally, in this... Figure 7 In the example, as the air volume (Air Flow / 10) [kg / h] (curve g) of the blower 23 increases, the heating capacity (Heat Capacity) [KW] (curve h) of the vehicle air conditioning unit 1 also increases.

[0087] From that Figure 7 As can be seen from the example, the vehicle air conditioning unit 1, under the control of the control device 100, can shorten the time when the intake refrigerant pressure Ps [bar] (curve d) is negative in the pressure regulation mode by improving the negative pressure state of the intake refrigerant pressure Ps [bar]. Therefore, in the vehicle air conditioning unit 1, even if the hot air heating operation mode is started in an extremely low temperature environment (e.g., below -40°C), the reliability of the low-pressure side components (compressor, etc.) will not be damaged, and the comfort of the occupants based on instant heating will not be compromised, enabling the execution of the hot air heating operation mode (FF control and FB control). In addition, the vehicle air conditioning unit 1, under the control of the control device 100, performs pre-processing after period B of the pressure regulation mode, thereby enabling stable execution of the hot air heating operation mode (FF control and FB control).

[0088] The embodiments of the present invention (the present embodiments) have been described in detail above with reference to the accompanying drawings. However, the specific structure is not limited to these embodiments. Even design changes that do not depart from the scope of the present invention are included in the present invention.

[0089] [Variation Example]

[0090] Hereinafter, variations of this embodiment will be described. In the structure of the above embodiment, the vehicle air conditioning unit 1 may also have an insulation component (not shown) provided on the outer surface of the storage tank 16. There are no particular limitations on the insulation component; for example, it can be any heat insulation component (not shown), any heater, etc.

[0091] Thus, by providing insulation on the outer surface of the storage tank 16 in the vehicle air conditioning unit 1, the refrigerant temperature on the low-pressure side can be set to a constant value or higher. As a result, even if the vehicle air conditioning unit 1 is activated in a hot air heating mode under extremely low temperature conditions (e.g., below -40°C), the reliability of the components (compressor, etc.) on the low-pressure side during activation can be further improved, and the comfort of the occupants based on instant heating can be further improved.

[0092] Furthermore, in the above embodiments, as Figure 5 In step S2, the pressure regulation mode is activated by the control device 100. Figure 6 The series of processes shown in steps S21 to S30 are not limited to this example, but the processing content of the pressure regulation mode (step S2) is not limited to this example. For example, the control device 100 may also perform only the following in the pressure regulation mode (step S2): Figure 6 Steps S21 to S24 are shown.

[0093] In this situation, after executing steps S21 to S24 in pressure regulation mode, the control device 100 ends the pressure regulation mode processing and proceeds the processing to... Figure 5 The hot air heating operation mode (FF control and FB control) shown in step S3. In this case, the vehicle air conditioning unit 1 can simplify the process of starting the hot air heating operation mode.

[0094] Symbol Explanation

[0095] 1: Vehicle air conditioning unit; 2: Compressor; 10: Refrigerant circuit; 10V: Hot gas bypass; 11: Outdoor heat exchange section; 12, 13: Flow path switching valve; 14, 15: Check valve; 16: Storage tank; 20: Air conditioning unit; 21, 22: Indoor heat exchange section; 23: Blower; 24, 25: Air baffle; 25A, 25B: Air inlet; 30: Heat transfer circuit; 31: Circulation pump; 32: Heater (ECH: Electric Coolant) Heater), 33: Temperature regulation object heat exchange section, 34: Refrigerant heat carrier heat exchange section, 34A: Flow path, 34B: Flow path, 40: Sensor section, 41: External gas sensor, 42: Compressor current sensor, 43, 43A: Refrigerant temperature sensor, 44: Refrigerant pressure sensor, 44A: Refrigerant pressure sensor, 44B: Refrigerant pressure sensor, 45: Supply air temperature sensor, 60: Input signal, 100: Control device (air conditioning ECU), 106: Bus.

Claims

1. A vehicle air conditioning unit, The vehicle air conditioning unit includes: A refrigerant circuit having a compressor, an indoor heat exchange section, an external heat exchange section, a pressure reducing section, and a hot gas bypass, wherein the hot gas bypass allows at least a portion of the refrigerant compressed in the compressor to be depressurized and returned to the compressor without passing through the indoor heat exchange section and the external heat exchange section; and a control device that controls the refrigerant circuit, wherein, The pressure-reducing section includes: a first pressure-reducing section disposed downstream of the indoor heat exchange section; and a second pressure-reducing section disposed in the hot gas bypass. The control device is capable of executing a hot gas heating operation mode in which a portion of the refrigerant compressed by the compressor flows to the indoor heat exchange section and the remaining portion flows to the hot gas bypass. When the hot gas heating operation mode is started, if it is determined that the refrigerant pressure on the suction side of the compressor is negative, a pressure regulation mode is executed to control the opening degree of the first pressure reducing section and the second pressure reducing section to a specified opening degree or above, and to increase the refrigerant pressure on the suction side of the compressor.

2. The vehicle air conditioning device as described in claim 1, characterized in that, In the pressure regulation mode, the control device controls the first pressure reducing section and the second pressure reducing section such that the opening degree of the first pressure reducing section is greater than or equal to the opening degree of the second pressure reducing section.

3. The vehicle air conditioning device as described in claim 1, characterized in that, In the pressure regulation mode, when the refrigerant pressure on the suction side of the compressor reaches a specific pressure, the control device makes the opening degree of the first pressure reducing section and the second pressure reducing section smaller than the current opening degree.

4. The vehicle air conditioning device as described in claim 1, characterized in that, In the pressure regulation mode, the control device controls the opening degree of the first pressure reducing section and the second pressure reducing section to the maximum opening degree.

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