Vehicle air conditioning device

Abstract

Provided is an air conditioner for a vehicle, the air conditioner being capable of improving the power consumption capability of consuming excess power while using conventional constituent parts. A vehicle air-conditioning device is provided with a first air-conditioning system capable of performing a heating operation using a heat pump, a second air-conditioning system capable of performing a heating operation using a heater, and a control unit for controlling at least the first air-conditioning system and the second air-conditioning system. When the remaining capacity of a battery that supplies power to the motor of the vehicle exceeds a predetermined threshold value, the control unit operates the first air-conditioning system in a defrosting mode while performing a heating operation by the second air-conditioning system. When the remaining capacity of the battery exceeds a predetermined threshold value during the heating operation performed by the first air-conditioning system, the control unit switches from the heating operation performed by the first air-conditioning system to the heating operation performed by the second air-conditioning system.

Description

Technical Field

[0001] The present invention relates to a vehicle air conditioning device, and more particularly to a vehicle air conditioning device that can effectively handle power consumption while using existing components. Background Art

[0002] Conventionally, in electric vehicles that use battery power to drive motors for travel, in order to avoid overcharging of the battery due to regenerative power generation when going downhill or decelerating, there is a known method of using a vehicle air conditioning device that performs cooling and heating of the vehicle interior to dissipate (consume) excess power.

[0003] Patent document 1 discloses a structure in which, in a vehicle air conditioning device having a first air conditioning system capable of performing a heating operation using a heat pump and a second air conditioning system capable of performing a heating operation using a heater, when the charge level of a battery exceeds a specified threshold, excess power is consumed by operating the heater of the second air conditioning system.

[0004] [Prior Technical Literature]

[0005] (Patent Document)

[0006] Patent Document 1: Japanese Patent Application Publication No. 2021-154911 Summary of the invention

[0007] [Problems to be solved by the invention]

[0008] However, in the configuration of Patent Document 1, since the ability to consume excess power depends on the performance of the second air conditioning system, there is a problem that the amount of power that can be consumed is limited.

[0009] An object of the present invention is to solve the above-mentioned problems of the prior art and to provide a vehicle air conditioning device which can improve the power consumption capacity of consuming excess power while using existing components.

[0010] [Technical means to solve the problem]

[0011] In order to achieve the aforementioned purpose, the first feature of the present invention is a vehicle air-conditioning device, comprising a first air-conditioning system capable of performing a heating operation using a heat pump, a second air-conditioning system capable of performing a heating operation using a heater, and a control unit for controlling at least the first air-conditioning system and the second air-conditioning system, wherein when the remaining capacity of a battery that supplies power to a motor of the vehicle exceeds a specified threshold, the control unit performs a heating operation implemented by the second air-conditioning system and operates the first air-conditioning system in a defrost mode.

[0012] In addition, a second feature is that when the remaining capacity of the battery exceeds a predetermined threshold during the heating operation performed by the first air conditioning system, the control unit switches from the heating operation performed by the first air conditioning system to the heating operation performed by the second air conditioning system.

[0013] In addition, the third feature is that the defrost mode is an operating mode in which the temperature of the air-conditioning refrigerant flowing in the flow path of the first air-conditioning system is made higher than the outside air temperature, and the heating expansion valve of the first air-conditioning system is fixed to a specified opening, and the compressor is driven to circulate the air-conditioning refrigerant in a gaseous state.

[0014] Furthermore, a fourth feature is that the predetermined opening degree of the heating expansion valve in the defrost mode is a low opening degree close to a closed valve.

[0015] (Effects of the Invention)

[0016] According to the first feature, in a vehicle air conditioning device having a first air conditioning system capable of performing a heating operation using a heat pump, a second air conditioning system capable of performing a heating operation using a heater, and a control unit that controls at least the first air conditioning system and the second air conditioning system, when the remaining capacity of a battery that supplies power to a motor of the vehicle exceeds a predetermined threshold, the control unit performs a heating operation implemented by the second air conditioning system and operates the first air conditioning system in a defrost mode, so that when the charge amount of the battery exceeds the predetermined threshold, overcharging of the battery can be avoided by consuming power while performing the heating operation. In addition, in addition to operating the second air conditioning system using the heater, the first air conditioning system using the heat pump is also operated in a defrost mode, thereby improving the power consumption capacity of the entire system while using existing components.

[0017] According to the second feature, when the remaining capacity of the battery exceeds a predetermined threshold value during the heating operation performed by the first air conditioning system, the control unit switches from the heating operation performed by the first air conditioning system to the heating operation performed by the second air conditioning system. Therefore, when the remaining capacity of the battery is below the predetermined threshold value, power saving can be achieved by performing the heating operation with good energy efficiency using the heat pump. In other words, only when the remaining capacity of the battery exceeds the predetermined threshold value, switching to the inefficient operation performed by the second air conditioning system can be performed to improve the power consumption capacity.

[0018] According to the third feature, the defrost mode is an operating mode in which the temperature of the air-conditioning refrigerant flowing in the flow path of the first air-conditioning system is made higher than the outside air temperature, and the heating expansion valve of the first air-conditioning system is fixed to a specified opening, and the compressor is driven to circulate the air-conditioning refrigerant in a gaseous state; therefore, existing components can be used to improve power consumption capacity.

[0019] According to the fourth feature, the predetermined opening degree of the heating expansion valve in the defrost mode is a low opening degree close to a closed valve, so the operation in the defrost mode can be performed by the same control as the heating operation. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 This is a schematic diagram of an electric vehicle to which the vehicle air conditioning device according to the present embodiment is applied.

[0021] Figure 2 It is a schematic diagram showing a circuit structure of the vehicle air conditioning device according to the present embodiment.

[0022] Figure 3 This is a block diagram showing the overall structure of a vehicle air conditioning device.

[0023] Figure 4 This is a circuit diagram showing the state of the heating operation when the remaining capacity of the battery is equal to or less than a predetermined threshold value.

[0024] Figure 5 This is a circuit diagram showing the state of the heating operation when the remaining capacity of the battery exceeds a predetermined threshold value.

[0025] Figure 6 This is a flowchart showing the flow of power consumption control according to this embodiment. DETAILED DESCRIPTION

[0026] Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the drawings. Figure 1 1 is a schematic diagram of an electric vehicle 1 to which the vehicle air conditioning device of the present embodiment is applied. The electric vehicle 1, which drives the motor M with the power of the battery B to travel, may be a so-called pure electric vehicle having a battery and a motor, a fuel cell vehicle having a power generation system implemented by a fuel cell, or a hybrid vehicle using a motor and an internal combustion engine.

[0027] A battery box 10 is provided under the floor of a vehicle cabin 2 of the electric vehicle 1 to accommodate a battery B such as a lithium ion battery. A motor room 6 provided at the front of the vehicle body includes a motor M, a power conversion device 7, a branch unit 4, and a charger 5.

[0028] The driving force of the motor M is transmitted to the pair of left and right front wheels WF via the shaft 8. The power conversion device 7 is fixed to the upper part of the motor M and is electrically connected to the battery box 10 via the power cable 9. The power conversion device 7 controls the driving of the motor M using the power supplied from the battery B.

[0029] The branch unit 4 and the charger 5 are arranged side by side in the vehicle width direction on the upper part of the power conversion device 7. The branch unit 4 and the battery box 10 are electrically connected via a cable 3 having connectors at both ends.

[0030] Figure 2 Schematic diagram showing the circuit structure of the vehicle air conditioner of the present embodiment. The vehicle air conditioner is configured to include: a heat pump circuit 24 for circulating a refrigerant for air conditioning including a refrigerant gas such as R1234yf; a temperature control circuit 25 for circulating a heat medium including water or a coolant; and a battery temperature control circuit 26 for circulating a heat medium for a battery including water or a coolant.

[0031] In the first flow path 51 constituting the heat pump circuit 24, there are provided a compressor 30 for pressurizing the refrigerant for air conditioning, an external heat exchanger 32, an expansion valve 37 for heating, a water-cooled condenser 42, a high-pressure solenoid valve 38 for opening and closing the flow path, a check valve 36 for preventing the backflow of the refrigerant for air conditioning, an expansion valve 35 for cooling, an evaporator 34 as a heat absorber, a low-pressure solenoid valve 33 for opening and closing the flow path, a liquid separation accumulator 31 as a gas-liquid separator, an expansion valve 39 for battery temperature control, and a cooler 40 as a heat exchanger.

[0032] The evaporator 34 performs heat exchange between the low-temperature air-conditioning refrigerant passing through the tubes disposed therein and the air in contact with the heat dissipation fins disposed outside the tubes. That is, the air-conditioning refrigerant passing through the evaporator 34 evaporates and gasifies due to heat absorption, thereby cooling the surrounding air, and condensing on the surface of the heat dissipation fins to perform dehumidification. The liquid separation accumulator 31 performs gas-liquid separation of the air-conditioning refrigerant and supplies only the gas phase of the air-conditioning refrigerant to the compressor 30.

[0033] In the second flow path 52 constituting the temperature control circuit 25 as the auxiliary heating system, there are provided a water pump 41 for pressurizing the heat medium, a water-cooled condenser 42 as an outdoor heat exchanger, an electric coolant heater (ECH) 43 as a heater for heating the heat medium, a heater core 44 as a radiator, and a liquid storage tank 45 for temporarily storing the heat medium to absorb the pressure change or flow change caused by thermal expansion. The heater core 44 disposed on the downstream side of the electric coolant heater 43 performs heat exchange between the high-temperature heat medium passing through the pipe disposed inside the heater core 44 and the air in contact with the heat dissipation fins disposed outside the pipe.

[0034] The cooler 40 and the battery B having a flow path for the battery heat medium are interposed in the third flow path 53 constituting the battery temperature control circuit 26. The cooler 40 has a function of exchanging heat between the air conditioning refrigerant flowing through the first flow path 51 and the battery heat medium flowing through the third flow path 53 and circulating the battery heat medium.

[0035] The heating expansion valve 37, the cooling expansion valve 35 and the battery temperature control expansion valve 39 respectively have the function of reducing the pressure to spray the high-pressure liquid air-conditioning refrigerant in a mist form for easy gasification, and are constructed so that the opening degree can be adjusted between fully closed and fully open.

[0036] Figure 3 1 is a block diagram showing the overall structure of the vehicle air conditioner 50. The vehicle air conditioner 50 includes an operation unit 20, a state of charge (SOC) acquisition unit 21, a battery temperature sensor 22, a control unit 23, a heat pump circuit 24 as a first air conditioning system, a temperature control circuit 25 as a second air conditioning system, and a battery temperature control circuit 26. The control unit 23, which is composed of a microcomputer and a substrate, can be disposed inside the power conversion device 7, for example.

[0037] The operation unit 20 operated by the occupant is a so-called car air conditioner operation panel, which receives instructions including the temperature setting of the vehicle interior 2, the switching of the internal air circulation and the external air introduction, the switching of the air supply outlet, etc. The SOC acquisition unit 21 acquires the remaining capacity (State of charge, SOC) of the battery B by measuring the charge and discharge current and the cell voltage of the battery B, and the battery temperature sensor 22 detects the temperature of the battery B.

[0038] Figure 2 In the circuit shown, in addition to multiple temperature sensors for detecting the temperature of each flow path, there are also a rotation speed sensor of the compressor 30, a vehicle interior temperature sensor, an outside air temperature sensor, etc.; the control unit 23 controls the heat pump circuit 24, the temperature control circuit 25, and the battery temperature control circuit 26 based on the output signals of various sensors including the battery temperature sensor 22 in addition to the operation content of the operation unit 20. The control unit 23 can switch between operation modes such as heating operation, dehumidification and heating operation, cooling operation, and dehumidification and cooling operation for the air conditioning of the vehicle interior 2.

[0039] The control unit 23 drives and controls the compressor 30, the heating expansion valve 37, the low-pressure electromagnetic valve 33, the high-pressure electromagnetic valve 38, and the cooling expansion valve 35 that constitute the heat pump circuit 24. In addition, the control unit 23 drives and controls the water pump 41 and the water heater 43 that constitute the temperature control circuit 25. Furthermore, the control unit 23 drives and controls the battery temperature control expansion valve 39 according to the temperature of the battery B and other conditions.

[0040] Here, in the electric vehicle 1 that drives the motor M with the power of the battery B to travel, in order to avoid overcharging of the battery B due to regenerative power generation when going downhill or decelerating, it is necessary to dissipate (consume) excess power. In this regard, in the prior art, a temperature control circuit that can perform heating operation with a heater is operated to increase power consumption, but there is a problem that the power consumption performance depends on the performance of the temperature control circuit and the amount of power that can be consumed is limited.

[0041] In this regard, the vehicle air conditioning device 50 of the present embodiment is characterized in that when the remaining capacity SOC of the battery B exceeds the specified threshold value th, a heating operation is performed by the temperature control circuit 25 using the water heating heater 43, and the heat pump circuit 24 using the heat pump is operated in a defrost mode, thereby improving the overall power consumption capacity of the system.

[0042] Here, the so-called defrost mode is an operation mode for melting and removing (defrosting) the frost attached to the external heat exchanger 32 of the heat pump circuit 24. The attachment of frost to the external heat effector 32 occurs, for example, due to heating operation in an atmosphere where the outside air temperature is below 5°C and the humidity is above 70%. This is because the surroundings of the external heat exchanger 32, which functions as an evaporator during the heating operation, are cooled and the moisture in the air condenses. In addition, since when frost adheres to the external heat exchanger 32, the heat exchange efficiency decreases and the heating effect becomes worse, defrosting is appropriately performed by operating in the defrost mode.

[0043] In the defrosting mode of this embodiment, the temperature of the air conditioning refrigerant flowing in the first flow path 51 of the heat pump circuit 24 is higher than the outside air temperature, and the air conditioning refrigerant circulates in sequence through the compressor 30, the water-cooled condenser 42, the heating expansion valve 37, the external heat exchanger 32, the low-pressure electromagnetic valve 33, and the liquid separation accumulator 31. In this circulation path, if the conventional defrosting mode is used, the target defrosting cannot be performed without using the external heat exchanger 32 as a radiator, so it is necessary to control the refrigerant temperature to a temperature higher than the outside air temperature. For this reason, in the water-cooled condenser 42, the temperature difference between the air conditioning refrigerant flowing through the first flow path 51 and the temperature control circuit 25 is important, and the temperature of the temperature control circuit 25 must be higher than the refrigerant to prevent heat from being transferred from the refrigerant to the temperature control circuit 25. Among them, since the power consumption of this case is used, as long as the power can be discarded, it is not limited to this. This is controlled by the control unit 23 to control the water heating heater 43, the compressor 30, and the heating expansion valve 37. The air conditioning refrigerant in the gas phase is compressed at the compressor 30 and becomes high temperature. The refrigerant passes through the water-cooled condenser 42 and then expands at the heating expansion valve 37 to become high temperature and low pressure. However, the refrigerant temperature is controlled by the control unit 23 at the external heat exchanger 32 to be higher than the temperature of the outside air, so heat is dissipated. The refrigerant then circulates through the low-pressure solenoid valve 33 and the liquid separation accumulator 31 in sequence. At this time, the refrigerant exchanges heat with the temperature control circuit 25 at the water-cooled condenser 42. As long as the water pump 41 of the temperature control circuit 25 is driven, the heat medium will flow, and the vehicle interior will be heated by the heater core 44. In addition, in the defrost mode, the external heat exchanger 32 exchanges heat with the outdoor air by the air supply fan (HVAC blower) not shown in the figure. The air supply fan that supplies air to the vehicle interior 2 does not supply air to the external heat exchanger 32, but supplies air to the heater core 44 and the evaporator 34. Conventional heating can be performed without stopping the air supply fan that supplies air to the vehicle interior 2. In addition, the radiator fan that sends air through the external heat exchanger 32 stops during defrosting, but does not stop during the implementation of this power consumption to promote heat dissipation of the external heat exchanger 32. In addition, the opening of the heating expansion valve 37 in the defrost mode and the set temperature of the air conditioning refrigerant can be changed in various ways. In addition, by adjusting the heating expansion valve 37 in a manner that makes the refrigerant temperature of the water-cooled condenser 42 lower than the heat medium temperature of the water-cooled condenser 42, the heat of the heating hot water circuit can be dissipated to the outside of the vehicle, and the ECH can consume (dissipate) more electricity than the electricity required for heating.

[0044] Figure 4This is a circuit diagram showing the state of heating operation when the remaining capacity SOC of the battery B is below the predetermined threshold value th. When the remaining capacity SOC of the battery B is below the predetermined threshold value th, the heating operation is in principle performed only in the heat pump circuit 24 with good energy efficiency, but when the heating capacity is insufficient, the so-called auxiliary heating system, that is, the temperature control circuit 25, can be operated together.

[0045] The control unit 23, when performing heating operation by means of the heat pump circuit 24, drives the compressor 30 with the heating expansion valve 37 slightly opened, the low-pressure solenoid valve 33 opened, the high-pressure solenoid valve 38 closed, the cooling expansion valve 35 closed, and the battery temperature control expansion valve 39 closed.

[0046] Thus, the refrigerant for air conditioning circulates sequentially through the compressor 30, the water-cooled condenser 42, the expansion valve 37 for heating, the external heat exchanger 32, the low-pressure solenoid valve 33, and the liquid-separating accumulator 31. In this circulation path, the gas phase of the refrigerant for air conditioning is compressed at the compressor 30 and becomes high temperature. Thereafter, the refrigerant exchanges heat with the temperature control circuit 25 at the water-cooled condenser 42, and the vehicle interior is heated by the heater core 44. At this time, it changes to a liquid phase at the water-cooled condenser 42. The refrigerant then expands at the heating expansion valve 37, becomes low temperature and low pressure, and continuously vaporizes. The low temperature and low pressure refrigerant absorbs heat as vaporization heat at the external heat exchanger 32, and the refrigerant temperature rises to the same level as the outside air temperature. The refrigerant then circulates sequentially through the low-pressure solenoid valve 33 and the liquid-separating accumulator 31.

[0047] In addition, when using the heat pump circuit 24 for dehumidification and heating operation, the compressor 30 is driven with the heating expansion valve 37 slightly opened, the low-pressure solenoid valve 33 opened, the cooling expansion valve 35 slightly opened, and the battery temperature control expansion valve 39 closed.

[0048] Thus, the air conditioning refrigerant circulates sequentially through the compressor 30, the water-cooled condenser 42, the heating expansion valve 37, the external heat exchanger 32, the low-pressure solenoid valve 33, and the liquid separation accumulator 31, and the air conditioning refrigerant passing through the check valve 36 circulates through the cooling expansion valve 35 and the evaporator 34. The air conditioning refrigerant in the liquid phase passing through the check valve 36 expands at the cooling expansion valve 35 to become low pressure, and absorbs heat at the evaporator 34 to evaporate and gasify. As a result, the air dehumidified by the evaporator 34 is heated by the heater core 44, so that the dehumidified warm air can be supplied to the vehicle interior 2.

[0049] Figure 5This is a circuit diagram showing the state of heating operation when the remaining capacity SOC of the battery B exceeds the predetermined threshold value th. When the remaining capacity SOC of the battery B exceeds the predetermined threshold value th, the control unit 23 starts the heating operation implemented by the temperature control circuit 25 as the second air conditioning system, and operates the heat pump circuit 24 as the first air conditioning system in the defrost mode.

[0050] The heating operation implemented by the temperature control circuit 25 is performed by operating the water heating heater 43 and operating the water pump 41. As a result, the air is heated by the heater core 44, so that warm air can be supplied to the vehicle interior 2. On the other hand, in the heat pump circuit 24, the operation in the defrost mode is performed. As described above, in the defrost mode, the temperature of the air-conditioning refrigerant flowing in the first flow path 51 of the heat pump circuit 24 is made higher than the outside air temperature, and the heating expansion valve 37 is fixed to a specified opening degree that is slightly opened from the closed valve state, and in this state, the compressor 30 is operated.

[0051] Figure 6 This is a flowchart showing the flow of power consumption control of the present embodiment. Power consumption control is executed as a timer interrupt process at a predetermined time interval. In step S1, it is determined whether the remaining capacity SOC of battery B exceeds a predetermined threshold value th. The predetermined threshold value th can be set to 90%, for example. If a positive determination is made in step S1, that is, it is determined that the remaining capacity SOC of battery B exceeds the predetermined threshold value th, it is determined that it is not suitable for continued regenerative charging, and the process proceeds to step S2. On the other hand, if a negative determination is made in step S1, that is, when the remaining capacity SOC of battery B is below the predetermined threshold value th, it is determined that it is still in a state where regenerative charging is possible, and a series of controls are terminated.

[0052] In step S2, the heating operation performed by the temperature control circuit 25 is started, and in the next step S3, the operation of the heat pump circuit 24 in the defrost mode is started. In this way, it is possible to consume power while performing the heating operation to avoid overcharging of the battery B. In addition, in addition to operating the temperature control circuit 25 using the water heating heater 43, the heat pump circuit 24 using the heat pump is operated in the defrost mode, thereby improving the power consumption capacity of the entire system.

[0053] Furthermore, when the remaining capacity SOC of the battery B exceeds a predetermined threshold value th during the heating operation performed by the heat pump circuit 24, the control unit 23 performs control to switch from the heating operation performed by the heat pump circuit 24 to the heating operation performed by the temperature control circuit 25. Thus, when the remaining capacity SOC of the battery B is below the predetermined threshold value th, power saving can be achieved by using the heating operation with good energy efficiency of the heat pump circuit 24. In other words, only when the remaining capacity SOC of the battery B exceeds the predetermined threshold value, switching to the inefficient operation performed by the temperature control circuit 25 can be performed to improve the power consumption capacity.

[0054] The form of the electric vehicle, the flow path structure of the heat pump circuit or the temperature control circuit, the structure of the compressor, the heater, the heat exchanger, the expansion valve, etc. are not limited to the above-mentioned embodiments, and various changes can be made. For example, the heat pump circuit can also have an indoor air-cooled condenser, or have a circuit that not only cools the battery but also heats it. The vehicle air conditioning device of the present invention is not limited to pure electric vehicles that use the power of the battery to drive the motor for driving, but can also be applied to various vehicles such as hybrid vehicles and fuel cell vehicles.

[0055] Reference numerals

[0056] 1: Electric vehicle (vehicle)

[0057] 23: Control Department

[0058] 24: First air conditioning system (heat pump circuit)

[0059] 25: Second air conditioning system (temperature control circuit)

[0060] 37: Heating expansion valve

[0061] 43: Heater

[0062] 50: Vehicle air conditioning device

[0063] 51: First flow path (flow path)

[0064] M: Motor

[0065] B: Battery

[0066] SOC: remaining capacity of the battery

[0067] th: specified threshold

Claims

1. A vehicle air conditioning device comprising a first air conditioning system capable of performing a heating operation using a heat pump, a second air conditioning system capable of performing a heating operation using a heater, and a control unit for controlling at least the first air conditioning system and the second air conditioning system, When a remaining capacity of a battery that supplies electric power to a motor of the vehicle exceeds a predetermined threshold, the control unit performs a heating operation by the second air-conditioning system and operates the first air-conditioning system in a defrost mode.

2. The vehicle air conditioning device according to claim 1, wherein: When the remaining capacity of the battery exceeds a predetermined threshold value during the heating operation performed by the first air-conditioning system, the control unit switches the heating operation performed by the first air-conditioning system to the heating operation performed by the second air-conditioning system.

3. The vehicle air conditioning device according to claim 1 or 2, wherein: The above-mentioned defrost mode is the following operating mode: the temperature of the air-conditioning refrigerant flowing in the flow path of the above-mentioned first air-conditioning system is made higher than the outside air temperature, and the heating expansion valve of the above-mentioned first air-conditioning system is fixed to a specified opening, and the compressor is driven to make the above-mentioned air-conditioning refrigerant circulate in a gaseous state.

4. The vehicle air conditioning device according to claim 3, wherein: The predetermined opening degree of the heating expansion valve in the defrost mode is a low opening degree close to a closed valve.

Images