Vehicle air conditioner

Abstract

[Problem] To execute control of a refrigerant circuit (control of the rotational speed of a compressor) capable of making energy consumption of the compressor more efficient when continuously operating in a hot gas heating operation mode. [Solution] A vehicle air conditioner according to the present invention comprises: a refrigerant circuit that decompresses a refrigerant discharged from a compressor and returns the refrigerant to the compressor; a vehicle interior air conditioner that controls the temperature of air blown into the vehicle interior by an interior heat exchange unit of the refrigerant circuit; and a control device that controls the refrigerant circuit and the vehicle interior air conditioner on the basis of input information. The refrigerant circuit is provided with a refrigerant flow path that is capable of executing a hot gas heating operation mode and includes a hot gas bypass, which decompresses part of the refrigerant compressed by the compressor and causes the refrigerant to flow to the suction side of the compressor without passing through the interior heat exchange unit. In the hot gas heating operation mode in which part of the refrigerant compressed by the compressor is caused to flow to the interior heat exchange unit and the remainder is caused to flow to the hot gas bypass, the control device performs control to variably set the target pressure of the refrigerant circuit within a range in which the heating demand can be maintained, in consideration of the necessary capacity required by the set heating demand and vehicle demand.

Description

Vehicle air conditioning system

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

[0002] Air conditioners for electric vehicles (EVs) that do not have a combustion-based heat source such as an engine or for vehicles with a low heat output from a combustion-based heat source typically use a heat pump as a heat source. In normal heating operation, these air conditioners absorb heat from outside air using an exterior heat exchanger that functions as a heat absorber, and heat the air to be blown into the vehicle cabin using a heat exchanger in the interior air conditioner that functions as a heat radiator. Therefore, when the outside air temperature is extremely low during normal heating operation, it becomes difficult to absorb heat from the outside air, resulting in a decrease in heating capacity.

[0003] In contrast, the hot gas heating operation mode executes a cycle in which high-temperature, high-pressure refrigerant discharged from the compressor of the heat pump flows through a heat exchanger of the vehicle interior air conditioner, and then decompresses and is drawn into the compressor without passing through an exterior heat exchanger, thereby enabling heating operation in extremely low-temperature outdoor air environments where it is difficult for the exterior heat exchanger to absorb heat. In this hot gas heating operation mode, a bypass refrigerant flow path (hot gas bypass) is provided in the refrigerant circuit, which decompresses and returns a portion of the high-temperature, high-pressure refrigerant discharged from the compressor to the compressor without passing through the heat exchanger of the vehicle interior air conditioner. By flowing a portion of the refrigerant compressed by the compressor through the heat exchanger of the vehicle interior air conditioner and flowing the remainder through the hot gas bypass, it is possible to adjust the amount of heat input and heat release during operation (see Patent Document 1 below).

[0004] Japanese Patent Application Laid-Open No. 2023-46604

[0005] Conventionally, in hot gas heating operation mode, in order to perform continuous operation in response to various demands, the compressor in the refrigerant circuit is operated at a set speed close to its capacity limit so that the energy consumption (heat input) of the compressor exceeds the heat dissipation required for various demands. However, if the hot gas heating operation mode continues for a long period of time, the energy consumption of the compressor reduces the remaining power in the battery, which causes a problem of shortening the driving range of the electric vehicle.

[0006] The present invention has been proposed in light of these circumstances. That is, an object of the present invention is to control the refrigerant circuit (control the compressor rotation speed) in a way that can efficiently improve the energy consumption of the compressor when the hot gas heating operation mode is continuously operated.

[0007] In order to solve the above problems, the present invention provides a vehicle air conditioning system including a refrigerant circuit that reduces the pressure of refrigerant discharged from a compressor and returns the refrigerant to the compressor, an interior air conditioning system that adjusts the temperature of air to be blown into a vehicle cabin using an interior heat exchanger of the refrigerant circuit, and a control device that controls the refrigerant circuit and the interior air conditioning system based on input information, wherein the refrigerant circuit has a refrigerant flow path that is capable of executing a hot gas heating operation mode that includes a hot gas bypass that reduces the pressure of a portion of the refrigerant compressed by the compressor and flows it to an intake side of the compressor without passing through the interior heat exchanger, and the control device controls the vehicle air conditioning system to variably set a target pressure of the refrigerant circuit within a range that allows the heating demand to be maintained, taking into account a set heating demand and a required capacity determined by a vehicle demand.

[0008] In a vehicle air conditioning system having such characteristics, when the hot gas heating operation mode is continuously operated, it is possible to perform control of the refrigerant circuit (control of the compressor rotation speed) that can efficiently improve the energy consumption of the compressor.

[0009] 1 is an explanatory diagram showing an example of the configuration of a vehicle air conditioner according to an embodiment of the present invention. FIG. 1 is an explanatory diagram showing a control device for a vehicle air conditioner. FIG. 2 is an explanatory diagram showing the hardware configuration of a control device for a vehicle air conditioner mounted on an electric vehicle (EV). FIG. 2 is an explanatory diagram showing refrigerant circuit operation in a hot gas heating operation mode in a vehicle air conditioner according to an embodiment of the present invention. FIG. 3 is a flow diagram showing pre-processing for a mode selection process performed by a control device. FIG. 4 is a flow diagram showing a mode selection process performed by a control device. FIG. 5 is a block diagram of a control device that performs variable PSO control after transition to a second selection mode. FIG. 6 is an explanatory diagram showing an example of a data map for determining the range of a target value PCO of a high-pressure side refrigerant pressure from a target outlet temperature TAO. FIG. 7 is an explanatory diagram showing a method for determining a target operating state. FIG. 8 is an explanatory diagram showing the relationship between PCO and PSO (a linear relationship that is inversely proportional) at a constant target outlet temperature.

[0010] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the following description, the same reference numerals in different drawings denote parts with the same functions, and duplicated descriptions in each drawing will be omitted as appropriate.

[0011] [Configuration of Refrigerant Circuit, etc. in Vehicle Air Conditioner] Fig. 1 shows an example of the configuration of a vehicle air conditioner 1 according to an embodiment of the present invention. The configuration example shown here is just an example, and the present invention is not particularly limited to a specific configuration.

[0012] The vehicle air conditioner 1 includes a refrigerant circuit 10 and a vehicle interior air conditioner 20. The refrigerant circuit 10 has a refrigerant flow path that decompresses the refrigerant discharged from the compressor 2 and returns it to the compressor 2. The compressor 2, interior heat exchangers 21 and 22 provided inside the vehicle interior air conditioner 20, and an exterior heat exchanger 11 provided outside the vehicle cabin are arranged along the refrigerant flow path. The interior heat exchangers 21 and 22 are provided for heat exchange between the refrigerant and air flowing through the vehicle interior air conditioner 20, and the exterior heat exchanger 11 is provided for heat exchange between the refrigerant and outside air outside the vehicle cabin. For example, the interior heat exchanger 21 is used to heat the air, and the interior heat exchanger 22 is used to cool the air. A refrigerant pressure sensor 44B is provided downstream of the interior heat exchanger 21 in the refrigerant flow path to detect an outlet refrigerant pressure (high-pressure side refrigerant pressure) Pci from the interior heat exchanger 21.

[0013] The compressor 2 compresses the refrigerant and circulates it through the refrigerant circuit 10. The refrigerant compressed by the compressor 2 is reduced to a required pressure by selectively passing through an appropriately selected refrigerant flow path, for example, a first pressure reduction section V1, a second pressure reduction section V2, a third pressure reduction section V3, or a fourth pressure reduction section V4, which are expansion valves. The refrigerant circuit 10 is provided with flow path switching valves 12 and 13 for switching the refrigerant flow path and check valves 14 and 15 for restricting the flow direction of the refrigerant. An accumulator 16 is provided upstream of the compressor 2 in the refrigerant circuit 10 to recover liquid refrigerant and separate the refrigerant into gas and liquid. A refrigerant pressure sensor 44A is provided between the accumulator 16 and the compressor 2 to detect the suction refrigerant pressure (low-pressure side refrigerant pressure) Ps sucked into the compressor 2.

[0014] As described above, the vehicle interior air conditioner 20 includes the interior heat exchangers 21, 22. Air introduced from the interior or exterior of the vehicle by the blower 23 passes through the interior heat exchangers 21, 22 to adjust the temperature and is then blown into the vehicle interior. The vehicle interior air conditioner 20 is also provided with an air damper 24. When the air damper 24 shown in FIG. 1 is fully open, the air introduced by the blower 23 passes through both the interior heat exchangers 21, 22 and is then blown into the vehicle interior.

[0015] When the air damper 24 is fully closed, it blocks the inlet side of the interior heat exchanger 21, and air introduced by the blower 23 passes only through the interior heat exchanger 22 before being blown into the cabin. Another air damper 25 provided in the vehicle interior air conditioner 20 switches the air introduced into the blower 23 between the interior and exterior. The air damper 25 can selectively close an air inlet 25A connected to the exterior or an air inlet 25B connected to the interior, allowing air to be introduced through either one of them. Furthermore, by placing the air damper 25 in an intermediate position, air can be introduced through both the air inlet 25A and the air inlet 25B.

[0016] Although the above-described examples of the outdoor heat exchange unit 11 and the indoor heat exchange units 21 and 22 have been described in which the refrigerant directly exchanges heat with the air, the refrigerant may also indirectly exchange heat with the air via a heat medium that has exchanged heat with the refrigerant. That is, the refrigerant may absorb heat from the air via the heat medium, or the refrigerant may release heat to the air via the heat medium.

[0017] As shown in FIG. 1 , the vehicle air conditioner 1 includes a heat medium circuit 30 for controlling the temperature of on-board equipment. The heat medium circuit 30 circulates a heat medium using a circulation pump 31, heats the heat medium using a heater (ECH: Electric Coolant Heater) 32, and recovers waste heat from on-board equipment (temperature control target) such as a battery using a temperature control target heat exchanger 33. The refrigerant circuit 10 and the heat medium circuit 30 are provided with a refrigerant-heat medium heat exchanger 34, which exchanges heat between the refrigerant and the heat medium in a flow path 34A through which the refrigerant flows and a flow path 34B through which the heat medium flows, as a heat exchanger for controlling the temperature of the on-board equipment. Such a heat medium circuit 30 is provided as needed.

[0018] [Control Device] The vehicle air conditioner 1 includes a control device (air conditioning ECU) 100 shown in Fig. 2. The control device 100 controls the refrigerant circuit 10 and the vehicle interior air conditioner 20, as described above, based on various input information J including user setting information and information from the vehicle, and detection signals from the sensor unit 40, and also controls the heat medium circuit 30 as necessary. The control device 100 is also connected to a database DB used when executing a control mode, which will be described later. Note that this database DB does not need to be located inside the vehicle air conditioner 1, as long as it can be connected to an external database DB using the vehicle's communication function.

[0019] The sensor unit 40, which inputs detection signals to the control device 100, includes, for example, an outside air sensor 41 that detects outside air conditions such as outside air temperature and outside air 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 a blown air temperature sensor 45 that detects the blown air temperature of the vehicle interior air conditioning unit 20.

[0020] In particular, the refrigerant pressure sensor 44 includes a refrigerant pressure sensor 44A that detects the suction refrigerant pressure (low-pressure side refrigerant pressure) Ps sucked 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 exchanger 21 (see FIG. 1). These sensors are only examples, and the sensor unit 40 is equipped with various sensors that detect information required for the control device 100 to perform various controls.

[0021] The control devices of the control device 100 are the compressor 2, the first pressure reduction section V1, the second pressure reduction section V2, the third pressure reduction section V3, the fourth pressure reduction section V4, and the flow path switching valves 12 and 13 in the refrigerant circuit 10, the blower 23, the air dampers 24 and 25 in the vehicle interior air conditioner 20, and the circulation pump 31 in the heat medium circuit 30. The control device 100 can switch between an outside air heat absorption heating operation mode in which outside air is absorbed by the exterior heat exchanger 11, and a hot gas heating operation mode in which high-temperature refrigerant compressed by the compressor 2 is dissipated in the interior heat exchanger 21 to heat the vehicle interior without outside air absorbing heat in the exterior heat exchanger 11.

[0022] [Configuration of Control Device in Electric Vehicle (EV)] As shown in Fig. 3 , the control device (air conditioning ECU) 100 provided in the vehicle air conditioner 1 is configured as a single ECU connected to various ECUs (Electronic Control Units) that control the electric vehicle (EV) via an in-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, and the like, and each piece of hardware is connected to one another via a bus 106.

[0023] The CPU 101 controls the control device 100 by executing various programs stored in the ROM 102. The ROM 102 is a non-volatile memory. For example, the ROM 102 stores programs executed by the CPU 101, data necessary for the CPU 101 to execute the programs, etc. The RAM 103 is a main storage device such as a dynamic random access memory (DRAM) or a static random access memory (SRAM).

[0024] For example, RAM 103 functions as a work area used by CPU 101 when executing a program. Input / output I / F 104 is connected to various sensors and monitors installed in the EV, and inputs data to CPU 101 and outputs data processed by CPU 101. In-vehicle communication I / F 105 is connected to an in-vehicle network L, and controls data transmission and reception with other ECUs set in the EV.

[0025] The control device 100 receives data related to the surrounding environment or data related to the driving status of the EV via the input / output I / F 104 or the in-vehicle communication I / F 105, and controls the above-mentioned vehicle air conditioning device 1 using a program executed by the CPU 101.

[0026] The EV is equipped with a battery B. The battery B is charged by connecting a charger plug PS to a battery plug BP, and power is supplied to the vehicle air conditioner 1 via the battery B. The state in which the plug PS is connected to the battery plug BP is transmitted to the control device 100 via the in-vehicle network L as a charger connection signal.

[0027] [Outdoor Air Heating Operation Mode] In the outdoor air heat absorption heating operation mode, the second pressure reduction section V2, the third pressure reduction section V3, the fourth pressure reduction section V4, and the flow path switching valve 12 are fully closed in the refrigerant circuit 10 shown in Fig. 1. Meanwhile, the flow path switching valve 13 is open, and the first pressure reduction section V1 is open.

[0028] In the outside air heat absorption heating operation mode, the high-temperature, high-pressure refrigerant discharged from the compressor 2 passes through the interior heat exchanger 21 in the vehicle interior air conditioner 20 and is depressurized in the first depressurization section V1. The low-pressure refrigerant passes through the exterior heat exchanger 11 and is returned to the compressor 2 via the flow path switching valve 13, the check valve 14, and the accumulator 16. At this time, the high-pressure refrigerant discharged from the compressor 2 condenses and releases heat in the interior heat exchanger 21, is depressurized in the first depressurization section V1 to become low-pressure refrigerant, absorbs heat and evaporates in the exterior heat exchanger 11, and returns to the compressor 2, completing a cycle. In the vehicle interior air conditioner 20, air introduced by the blower 23 is heated by the heat released in the interior heat exchanger 21 and is blown into the vehicle cabin.

[0029] [Refrigerant Circuit Operation in Hot Gas Heating Operation Mode] In the hot gas heating operation mode, the refrigerant is not allowed to absorb heat in the outdoor heat exchanger 11, and some or all of the refrigerant compressed by the compressor 2 is caused to release heat in the indoor heat exchanger 21 to heat the vehicle cabin. The operation of the refrigerant circuit 10 in the hot gas heating operation mode will be described with reference to Figure 4. In the illustrated refrigerant circuit 10, bold black lines indicate refrigerant flow paths through which high-pressure refrigerant flows, and hollow lines indicate refrigerant flow paths through which decompressed refrigerant flows. Furthermore, dashed lines in the refrigerant circuit 10 indicate refrigerant flow paths through which refrigerant does not flow, and dashed lines in the heat medium circuit 30 indicate that the flow of the heat medium is stopped.

[0030] 4, a portion of the high-temperature, high-pressure refrigerant discharged from the compressor 2 passes through the indoor heat exchanger 21 and the flow path switching valve 12, is decompressed in the third pressure reduction section V3 to become a low-pressure refrigerant, passes through the refrigerant heat medium heat exchanger 34, is separated into gas and liquid in the accumulator 16, and returns to the compressor 2. At this time, the refrigerant circuit 10 fully closes the first pressure reduction section V1 so that the refrigerant does not flow to the outdoor heat exchanger 11. Also, fully closes the fourth pressure reduction section V4 so that the refrigerant does not flow to the indoor heat exchanger 22.

[0031] The refrigerant circuit 10 has a hot gas bypass 10V that decompresses and returns at least a portion of the refrigerant compressed by the compressor 2 to the compressor 2 without passing through the indoor heat exchange unit 21 and the outdoor heat exchange unit 11, and is equipped with a refrigerant flow path that can execute a hot gas heating operation mode. In the hot gas bypass 10V, a portion of the high-temperature, high-pressure refrigerant is branched at a branch point P1 immediately downstream of the compressor 2, decompressed at a second decompression unit V2, and merged with the low-pressure refrigerant decompressed at a third decompression unit V3 at a junction point P2 immediately upstream of the accumulator 16.

[0032] By providing such a hot gas bypass 10V, in the hot gas heating operation mode, the liquid refrigerant condensed by heat radiation in the indoor heat exchanger 21 is mixed with the gas refrigerant that has passed through the hot gas bypass 10V to produce a gas-rich refrigerant that can be returned to the compressor 2. Furthermore, by increasing the flow rate of refrigerant flowing through the hot gas bypass 10V, the amount of heat radiation in the indoor heat exchanger 21 can be suppressed, and by adjusting the flow rate of refrigerant flowing through the hot gas bypass 10V by opening or closing the second pressure reduction section V2, the balance between the amount of heat radiation from the refrigerant circuit 10 and the amount of heat input to the compressor 2 can be maintained. In other words, the second pressure reduction section V2 functions as a flow rate adjustment section that adjusts the flow rate of refrigerant flowing through the hot gas bypass 10V.

[0033] In the hot gas heating operation mode, the refrigerant flow in the flow path passing through the indoor heat exchanger 21 is decompressed in the third decompression section V3, so that the refrigerant becomes high-pressure refrigerant upstream and low-pressure refrigerant downstream. In this case, it is important to maintain heating capacity that heat exchange does not occur in the refrigerant-heat medium heat exchanger 34 in the low-pressure flow path. In the vehicle interior air conditioner 20, air introduced by the blower 23 is heated by heat dissipated in the indoor heat exchanger 21 and then blown into the vehicle interior.

[0034] [Control of Hot Gas Heating Operation Mode] <Mode Selection Process> In the hot gas heating operation mode, control is performed to select between a first selection mode (fixed target pressure mode) and a second selection mode (variable target pressure mode) depending on the operating status of the automotive air conditioner 1, a heating request set by the user, a request from the vehicle, etc. The first selection mode (fixed target pressure mode) here is a heating performance priority mode for maximizing heating performance, in which the rotation speed of the compressor 2 of the refrigerant circuit 10 is continuously driven at the maximum rotation speed within the request, the target pressure of the refrigerant circuit 10 (for example, the target value PSO of the low-pressure side refrigerant pressure) is set to a fixed value, and the actually measured pressure is controlled to approach the target pressure.

[0035] In contrast, the second selection mode (variable target pressure mode) is a control mode that prioritizes requirements such as improving COP (Coefficient of Performance), and does not limit the rotation speed of the compressor 2 of the refrigerant circuit 10 to the maximum rotation speed, but variably sets the target pressure of the refrigerant circuit 10 (for example, the target value PSO of the low-pressure side refrigerant pressure) according to the requirement, and controls the actual measured pressure to approach the target pressure. In this second selection mode, control is performed to improve the efficiency of energy consumption of the refrigerant circuit 10, while ensuring that the hot gas heating operation mode is established (the heat input amount is equal to or greater than the heat release amount), and on the premise that the heating requirement set by the user (the set temperature and set air volume) is maintained.

[0036] The process shown in FIG. 5 is executed to select the first or second selection mode. When the process starts ("START"), a first preprocessing step S1, a second preprocessing step S2, and a third preprocessing step S3 are executed to calculate the required capacity TGQ based on the heating request set by the user and the request from the vehicle (vehicle request). The rotation speed limit of the compressor 2 due to the request from the vehicle is determined, and the mode selection process S4 is executed taking the calculated required capacity TGQ into consideration. This series of process flows from the start ("START") to the end ("END") is repeated at predetermined time intervals after the hot gas heating operation mode is initiated. The calculated required capacity TGQ is the energy per unit time [J / s] required to satisfy each of the above-mentioned requests.

[0037] In FIG. 5 , the first pre-processing S1 calculates a target heating capacity based on, for example, a heating request (set temperature and set airflow) set by a user. The second pre-processing S2 calculates the capacity required for temperature control of an on-board device (temperature control target) based on, for example, input information from the vehicle. Specifically, the target temperature control capacity is estimated from the target temperature of the temperature control target. At this time, the heat medium circuit 30 shown in FIG. 4 is activated in accordance with the request from the vehicle that controls the temperature of the on-board device. The third pre-processing S3 determines, for example, the vehicle's operating mode, such as a COP improvement operating mode (a so-called eco-operating mode) or a quiet operating mode (an operating mode that reduces noise), based on information from the vehicle, and obtains a rotation speed limit request for the compressor 2 associated with that operating mode.

[0038] 6, when the mode selection process S4 starts ("START"), a determination process S10 for selecting a mode is performed. In the determination process S10, a first determination process S10A determines whether or not the hot gas heating operation mode has just been started, and a second determination process S10B determines whether or not there is a margin for achieving the required capacity TGQ calculated in the first pre-processing S1 and the second pre-processing S2.

[0039] Here, the first determination process S10A determines whether the time t measured from the start of activation of the hot gas heating operation mode exceeds a set time t0, for example, and if the set time t0 is not exceeded, it is determined that the hot gas heating operation mode has just been activated (S10A: Y), and if the set time t0 is exceeded, it is determined that the hot gas heating operation mode has not just been activated (S10A: N). The set time t0 here can be set to a range as needed.

[0040] The second judgment process S10B judges that there is a surplus (S10B: Y) if the condition that the difference between the required capacity TGQ and the actual heating capacity Qhp is small or the required capacity TGQ itself is small (TGQ-Qhp<α or TGQ<β; α and β are different set values) continues to be met, and judges that there is no surplus (S10B: N) if this condition is not met.

[0041] In the judgment process S10, if the first judgment process S10A determines that the hot gas heating operation mode has just been started (S10A: Y), the transition process S11 to the first selection mode is executed, and even if the first judgment process S10A determines that the hot gas heating operation mode has not just been started (S10A: N), if the second judgment process S10B determines that there is no margin (S10B: N), the transition process S11 to the first selection mode is executed.

[0042] Then, in the judgment process S10, if the first judgment process S10A determines that it is not immediately after the hot gas heating operation mode has been started (S10A: N), and furthermore, the second judgment process S10B determines that there is room for improvement (S10B: Y), then the transition process S20 to the second selection mode is executed.

[0043] After the process S11 for transitioning to the first selection mode, the rotation speed limit request of the compressor 2 acquired in the third preprocessing S3 described above is confirmed, and fixed PSO control S12 (described later) is performed while driving the compressor 2 at the maximum rotation speed taking into consideration the rotation speed limit request. Furthermore, after the process S20 for transitioning to the second selection mode, variable PSO control S21 (described later) is performed.

[0044] <Fixed PSO Control After Transition to First Selection Mode> In the fixed PSO control (S12) after transition to the first selection mode, the control device 100 controls the refrigerant circuit 10 so that the high-pressure side refrigerant pressure of the refrigerant circuit 10 (such as the outlet refrigerant pressure Pci of the indoor heat exchange unit 21 and the discharge refrigerant pressure of the compressor 2) becomes equal to the target value PCO while continuing to drive the compressor 2 at the maximum rotation speed that takes into account the rotation speed limit request described above. At this time, the control device 100 controls the second pressure reducing unit V2 provided in the hot gas bypass 10V so that the actual measured value Ps of the low-pressure side refrigerant pressure of the refrigerant circuit 10 (such as the suction refrigerant pressure Ps of the compressor 2) becomes equal to the fixed target value PSO, and controls the airflow rate of the blower 23 so that the actual heating capacity Qhp of the vehicle air conditioner 1 becomes equal to the required capacity TGQ.

[0045] <Variable PSO Control After Shifting to Second Selection Mode> In the variable PSO control (S21) after shifting to the second selection mode, a target operating state of the refrigerant circuit 10 determined based on a user-set heating request and a vehicle request is determined, and control is performed so that an actual measurement value approaches the target operating state. The target operating state can be specified by the target pressures of the refrigerant circuit 10 (a target value PCO of the high-pressure side refrigerant pressure and a target value PSO of the low-pressure side refrigerant pressure), and is therefore represented as (PCO, PSO) below.

[0046] To determine the target operating states (PCO, PSO) of the refrigerant circuit 10, a data map stored in a database DB connected to the control device 100 can be used. When the control device 100 receives information on the user-set heating requirements (set temperature and set air volume) and vehicle requirements as input information J, it references this information in the operating state map stored in the database DB and determines a target range of operating states that satisfies the requirements. If the vehicle requirements include a requirement for improved COP or quiet operation, the control device 100 determines, as the target operating states (PCO, PSO), an operating state that can minimize the rotation speed of the compressor 2 within the determined target range of operating states.

[0047] An example of control logic for determining the target operating state is shown below, but the embodiment of the present invention is not particularly limited to this. In the following example, variable PSO control is described on the premise that the blown air temperature is fixed based on the heating request set by the user.

[0048] 7 , when a user-set heating request is input as input information J, the control device 100 calculates a target outlet temperature TAO based on the set temperature. The control device 100 then compares the calculated target outlet temperature TAO with a TAO / PCO map 110 acquired from the database DB to determine the range of the target value PCO for the high-pressure side refrigerant pressure.

[0049] The TAO / PCO map 110 used here can be a data map such as that shown in FIG. 8. This data map is a map that shows the relationship between the measured value Pci of the high-pressure side refrigerant pressure and the measured value of the discharge temperature of the compressor 2. It should be noted here that the relationship between the measured value Pci and the discharge temperature is such that, as shown by region M in the figure, the measured value Pci that can achieve the same discharge temperature is not a fixed value but a region. In the example shown in the figure, the measured value Pci that can achieve a discharge temperature of 55°C is in the range from 1.7 MPa to 1.9 MPa.

[0050] 8 is used as the TAO / PCO map, the target value PCO of the high-pressure refrigerant pressure required to maintain a constant target blow-off temperature TAO can be determined within a range defined by upper and lower limits. For example, if the target blow-off temperature TAO is fixed at 55°C, the corresponding target value PCO can be determined to be in the range of 1.7 MPa to 1.9 MPa.

[0051] The control device 100 then further narrows down the range of the target value PCO determined by the TAO / PCO map using a narrowing-down processing unit 111 to specify the target operating state (PCO, PSO). The narrowing-down processing unit 111 uses a required capacity TGQ that takes into account vehicle requirements and a rotation speed limit requirement NC of the compressor 2 that is based on the vehicle requirements.

[0052] As shown in Fig. 9, the narrowing processing unit 111 determines a further narrowed PCO range (for example, A1 to B1) for a PCO range (A0 to B0 in the figure) where the target air temperature TAO is constant, taking into consideration the required capacity TGQ and the rotation speed limit requirement NC. In Fig. 9, assuming that control is performed to keep the target air temperature TAO constant, if the target value PCO is increased, the rotation speed limit requirement NC must be set to a lower rotation speed, and the required capacity TGQ must also be set to a lower value. On the other hand, if the target value PCO is increased, the rotation speed limit requirement NC and the required capacity TGQ will decrease, and the COP will increase.

[0053] 9, when an upper limit of the rotational speed limit request NC is required within the range (A0 to B0) of the target value PCO for which the target outlet temperature TAO is constant, the value (A1) of the target value PCO corresponding to that upper limit becomes the lower limit of the target value PCO range. Also, when a lower limit of the required capacity TGQ is required within the range (A0 to B0) of the target value PCO for which the target outlet temperature TAO is constant, the value (B1) of the target value PCO corresponding to that lower limit becomes the upper limit of the target value PCO range. If the vehicle requirements include a request for improved COP and / or quieter operation, the rotational speed limit request NC selects the lowest rotational speed within the range. Therefore, in the illustrated example, the value of the target value PCO is specified as B1 to set the target operating state.

[0054] Under the condition that the target air temperature TAO is constant, the relationship between the target value PCO and the target value PSO is an inversely proportional linear relationship as shown in Fig. 10 (in the figure, a1 < a2 < a3, b1 < b2 < b3). Using this linear relationship, specific values ​​of the target value PSO for the specified specific values ​​of the target PCO are obtained, and the target operating state (PCO, PSO) is determined by combining these.

[0055] In this way, in the variable PSO control after transitioning to the second selection mode, the target operating state (PCO, PSO) is determined taking into account the required capacity TGQ and the rotational speed limit requirement NC based on the user-set heating requirement and the vehicle requirement, within a range in which the user-set heating requirement can be maintained (for example, the target air outlet temperature TAO is constant), and control is performed so that the actual measured value approaches the target value of the determined target operating state. According to this, when the vehicle requirement includes an improvement in COP or quiet operation, air conditioning control can be performed that satisfies the user-set heating requirement while suppressing the rotational speed of the compressor 2. Therefore, when the hot gas heating operation mode is continued, it is possible to suppress a reduction in the cruising range of the electric vehicle.

[0056] In the variable PSO control after transition to the second selection mode, target operating states (PCO, PSO) that satisfy not only the user-set heating request but also multiple vehicle requests are set, and whenever the user-set heating request or vehicle request is changed, the required capacity TGQ is calculated and the rotation speed limit request NC is confirmed, and a new target operating state (PCO, PSO) is set.

[0057] When the hot gas heating operation mode is selected, the vehicle air conditioner 1 immediately switches to the first selection mode as determined in the first determination process S10A. The compressor 2 is rotated at its maximum rotation speed while the refrigerant circuit 10 is controlled to bring the measured pressure closer to a fixed target pressure (e.g., the target value PSO of the low-pressure side refrigerant pressure). If the hot gas heating operation mode continues for a predetermined time and the actual heating capacity Qhp increases, creating a margin for achieving the required capacity TGQ, the second determination process S10B determines that there is a margin, and the vehicle air conditioner 1 switches to the second selection mode. As described above, the vehicle air conditioner 1 automatically switches to variable PSO control, in which target operating states (PCO, PSO) that satisfy the user-defined heating requirements and vehicle requirements are variably set as needed. If the user-defined heating requirements or vehicle requirements are changed after switching to the second selection mode and the second determination process S10B determines that there is no margin for achieving the required capacity TGQ, the vehicle air conditioner 1 switches from the second selection mode to the first selection mode.

[0058] In this way, when the vehicle air conditioner 1 continues operating in the hot gas heating operation mode, the system automatically transitions from the first selection mode to the second selection mode and from the second selection mode to the first selection mode, but since the heating requirements set by the user are maintained during this transition, the user can continue operating in the hot gas heating operation mode without sacrificing comfort. If the performance margin condition is met in the second determination process S10B, the system automatically transitions to efficient control of the refrigerant circuit 10 that satisfies various requirements, thereby enabling operation that avoids excessive energy consumption while ensuring user comfort.

[0059] The embodiments of the present invention have been described above in detail with reference to the drawings, but the specific configurations are not limited to these embodiments, and the present invention also includes design changes and the like that do not deviate from the gist of the present invention.

[0060] 1: Vehicle air conditioning device, 2: Compressor, 10: Refrigerant circuit, 10V: Hot gas bypass, 11: Outdoor heat exchanger, 12, 13: Flow path switching valve, 14, 15: Check valve, 16: Accumulator, 20: Vehicle interior air conditioning device, 21, 22: Indoor heat exchanger, 23: Blower, 24, 25: Air damper, 25A, 25B: Air inlet, 30: Heat medium circuit, 31: Circulation pump, 32: Heater, 33: Temperature control target heat exchanger, 34: Refrigerant heat medium heat exchanger, 34A, 34B: Flow path, 40: Sensor unit, 41: Outdoor air sensor, 42: Compressor current sensor, 43: Refrigerant temperature sensor, 44, 44A, 44B: Refrigerant pressure sensors, 45: Air supply temperature sensor, 100: Control device, J: Input information

Claims

1. A vehicle air conditioning system comprising a refrigerant circuit which reduces the pressure of refrigerant discharged from a compressor and returns it to the compressor, an interior air conditioning system which adjusts the temperature of air to be blown into the vehicle cabin by an interior heat exchanger of the refrigerant circuit, and a control device which controls the refrigerant circuit and the interior air conditioning system based on input information, wherein the refrigerant circuit has a refrigerant flow path capable of executing a hot gas heating operation mode including a hot gas bypass which reduces the pressure of a portion of the refrigerant compressed by the compressor and flows it to the suction side of the compressor without passing through the interior heat exchanger, and the control device, in the hot gas heating operation mode in which a portion of the refrigerant compressed by the compressor flows through the interior heat exchanger and the remainder flows through the hot gas bypass, controls to variably set a target pressure of the refrigerant circuit within a range in which the heating demand can be maintained, taking into consideration a set heating demand and a required capacity required by a vehicle demand.

2. The vehicle air conditioning system according to claim 1, wherein the control device determines an achievement margin for the required capacity, and if there is a margin, variably sets the target pressure, and if there is no margin, sets the target pressure to a fixed value by setting the compressor rotation speed to a maximum rotation speed.

3. The vehicle air conditioner according to claim 1, wherein the heating request is specified by a set temperature and a set air volume.

4. The vehicle air conditioning system of claim 3, wherein the control device determines a target range of high-pressure side refrigerant pressure within which the set temperature can be maintained, specifies a target value of the high-pressure side refrigerant pressure within the target range based on vehicle requirements, and specifies a target value of the low-pressure side refrigerant pressure from the specified target value of the high-pressure side refrigerant pressure.

5. The vehicle air conditioning system according to claim 1, wherein the refrigerant circuit includes a heat exchanger for adjusting the temperature of an in-vehicle device, and the vehicle requirements include a requirement for temperature adjustment of the in-vehicle device and a limitation requirement from the vehicle.

6. The vehicle air conditioner according to claim 5, wherein the restriction request is a request to restrict the rotation speed of the compressor associated with one or both of a quiet operation mode and a COP improvement operation mode of the vehicle.

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