Control device for vehicle air conditioning systems

Abstract

To suppress refrigerant passing noise generated when a load on an air conditioner is small.SOLUTION: When a pressure of a refrigerant discharged from a compressor 16 is lower than a predetermined value, a volume of air sent from a blower 30 that sends conditioned air into a passenger compartment of a vehicle is less than a predetermined value, and seating position adaptive control is being executed to control the volume of air according to a seating position of an occupant, an air conditioning request part 52 requests a cooling fan control part 54 to stop a cooling fan 26. When the cooling fan 26 is stopped, a temperature of the refrigerant passing through a condenser 18 increases, and a pressure also increases. This eliminates a gas-liquid two-phase state of the refrigerant, suppressing a generation of refrigerant passing noise.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a control device for an air conditioner for a vehicle.

Background Art

[0002] An air conditioner that adjusts the temperature and humidity in the passenger compartment of a vehicle is known. The refrigeration cycle circuit of the air conditioner has a condenser that cools the refrigerant circulating through the refrigeration cycle circuit after compressing it with a compressor. In order to sufficiently cool and liquefy the refrigerant with the condenser, the condenser is cooled by the cooling air sent by the cooling fan. Patent Document 1 below shows an air conditioner that stops the cooling fan when the refrigerant can be sufficiently liquefied by the condenser without cooling by the cooling fan.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] The refrigeration cycle circuit has an expansion valve disposed between the condenser and the evaporator. When the refrigerant passing through the expansion valve, particularly its orifice, is in a gas-liquid two-phase state containing both a liquid phase and a gas phase, a refrigerant passage sound is generated due to pressure fluctuations when the bubbles pass through the orifice.

[0005] An object of the present invention is to suppress the generation of refrigerant passage sound.

Means for Solving the Problems

[0006] The control device for an air conditioner for a vehicle according to the present invention is A control device for a vehicle air conditioning system, comprising: a cooling fan control unit that controls the operation of a cooling fan that blows cooling air onto both the condenser of the refrigeration cycle circuit and the radiator that cools the engine coolant; an air conditioning request unit that requests the cooling fan control unit to operate the cooling fan based on the operating state of the vehicle air conditioning system; and an engine cooling request unit that requests the cooling fan control unit to operate the cooling fan when the engine coolant temperature exceeds a predetermined value, wherein seating position adaptive control can be set to reduce the amount of air blower that supplies temperature and humidity adjusted air into the vehicle cabin according to the seating position of the occupants, and the air conditioning request unit, when the refrigerant pressure in the refrigeration cycle circuit of the air conditioner for a vehicle is lower than a predetermined value, and When the amount of air blown by the blower is less than a predetermined value and the seating position adaptive control is set, the cooling fan control unit is requested to stop the cooling fan, and the cooling fan control unit stops the cooling fan when it receives a request to stop the cooling fan from the air conditioning request unit and there is no request to operate the cooling fan from the engine cooling request unit. [Effects of the Invention]

[0007] When the cooling fan stops, the temperature of the refrigerant passing through the condenser in the refrigeration cycle circuit rises, increasing the refrigerant pressure. This reduces or eliminates the gaseous refrigerant, suppressing the generation of refrigerant passage noise. [Brief explanation of the drawing]

[0008] [Figure 1] This is a schematic diagram showing the general configuration of the air conditioning system and its control device according to this embodiment. [Figure 2] This is a pH diagram showing the state of the refrigerant in a refrigeration cycle circuit. [Figure 3] This flowchart shows the control mechanisms for suppressing refrigerant passage noise. [Modes for carrying out the invention]

[0009] Embodiments of the present invention will be described below with reference to the drawings. Figure 1 is a schematic diagram showing the configuration of a vehicle air conditioning system 10. Hereinafter, "air conditioning" will be referred to as "air conditioning". Figure 1 further shows the configuration related to the control of the air conditioning system 10 and the configuration related to the cooling system for the air conditioning system 10 and the engine (not shown) mounted on the vehicle in block diagrams.

[0010] The air conditioning system 10 includes a refrigeration cycle circuit 12 and an interior unit 14 that supplies temperature and humidity-controlled air into the vehicle's passenger compartment. The refrigeration cycle circuit 12 includes a compressor 16 that compresses the refrigerant, a condenser 18 that liquefies the compressed refrigerant by removing heat, an expansion valve 20 that depressurizes and expands the refrigerant through an orifice, an evaporator 22 where the expanded refrigerant liquefies and removes heat from the surroundings, and refrigerant piping 24 that connects these and forms a flow path for the refrigerant to circulate. Furthermore, the air conditioning system 10 includes a cooling fan 26 that blows cooling air onto the condenser 18. The cooling fan 26 may be an electric fan. The evaporator 22 is also one of the components of the interior unit 14. The interior unit 14 may be provided in the front seats and the rear seats, respectively.

[0011] The cooling unit 28, which includes a condenser 18 and a cooling fan 26, includes a radiator 30 that cools the engine (not shown) coolant. Coolant circulates between the radiator 30 and the engine, releasing the heat generated by the engine from the radiator 30. The cooling fan 26 blows cooling air onto the condenser 18 and also onto the radiator 30. The operation of the cooling fan 26 is controlled according to the operating status of the air conditioning system 10 and the engine. The operation of the cooling fan 26 will be described in detail later.

[0012] The indoor unit 14 includes an evaporator 22, a heater 32, a blower 34 that supplies air to the evaporator 22 and heater 32, and a unit case 36 that houses these components. A portion of the engine coolant is supplied to the heater 32 as needed. The blower 34 draws in either or both indoor and outdoor air into the unit case 36, generating an airflow directed towards either or both the evaporator 22 and heater 32. The ratio of indoor to outdoor air drawn into the unit case 36 is controlled by a door (not shown) located within the unit case 36. The amount of air supplied to the evaporator 22 and heater 32 is also controlled by another door. The evaporator 22 cools the airflow by removing heat from the supplied air. Additionally, water vapor in the cooled air condenses around the evaporator 22, dehumidifying the air. The heater 32 warms the supplied air. Air that has passed through either or both the evaporator 22 and the heater 32 is sent into the room. By sending the air that has passed through the evaporator 22 into the room, the room is cooled. By sending the air that has passed through the heater 32 into the room, the room is heated. Furthermore, by passing some or all of the air dehumidified by the evaporator 22 through the heater 32, dehumidification can be achieved without lowering the room temperature. The airflow rate of the blower 34 is adjustable. In the diagram, the blower 34 is shown as an axial fan, but the blower 34 is not limited to an axial fan; it may be a centrifugal fan such as a sirocco fan.

[0013] The air conditioning unit 10 can detect the seating position of the occupants and control the air conditioning according to their seating position. This control is referred to as seating position adaptive control. In seating position adaptive control, if only the driver is present, the air is blown towards the driver. If the driver and passenger are seated, but there are no passengers in the rear seats, the air is blown towards the front seats and not towards the rear seats. By performing seating position adaptive control, unnecessary operation of the air conditioning unit 10 is suppressed.

[0014] The air conditioning control device 38, which controls the air conditioning system 10, performs control based on environmental conditions such as outside air temperature, indoor temperature, and the seating position of the occupants, the operating state of the air conditioning system 10 indicated by the refrigerant pressure, and the set temperature and seating position applied control set by the occupants. The outside air temperature is detected by the outside air temperature sensor 40, and the indoor temperature is detected by the indoor temperature sensor 42. The refrigerant pressure is detected by the refrigerant pressure sensor 44 installed in the refrigerant piping 24 between the compressor 16 and the condenser. The seating position of the occupants is detected by the seating sensors 46 installed at each seat. The seating sensor 46 may be, for example, a pressure sensor, and detects the occupants' seating based on the pressure generated when the occupants are seated. The seating sensor 46 does not necessarily have to be installed in the driver's seat. The set temperature is set by the occupants using a temperature setter 48 installed on the instrument panel or the like. Furthermore, the seating position application control is set by the occupant using a seating position application control switch 50 located on the instrument panel or the like. By operating the seating position application control switch 50, it is selected whether or not to execute this control.

[0015] The air conditioning control device 38 calculates the air conditioning load and the airflow rate of the blower 34 based on the input information, and controls the output of the compressor 16 and the rotational speed of the blower 34 based on these. The output of the compressor 16 is controlled by the rotational speed of the compressor 16. Under conditions of high air conditioning load, such as high outside air temperature, high indoor temperature relative to the set temperature with a large difference, or a large number of occupants, the rotational speed of the compressor 16 is increased to circulate more refrigerant. At this time, the refrigerant pressure detected by the refrigerant pressure sensor 44 increases. The air conditioning control device 38 includes an air conditioning request unit 52 that requests the operation of the cooling fan 26 based on the operating state of the air conditioning unit 10. The air conditioning request unit 52 sends a request to the cooling fan control unit 54 to operate the cooling fan 26. The air conditioning request unit 52 requests the cooling fan control unit 54 to increase the rotational speed of the cooling fan 26 as the air conditioning load increases. ru.

[0016] The cooling fan control unit 54 receives requests from the engine cooling request unit 56 in addition to requests from the air conditioning request unit 52. The engine cooling request unit 56 requests the operation of the cooling fan when the engine coolant temperature detected by the coolant temperature sensor 58 exceeds a predetermined value.

[0017] The cooling fan control unit 54 controls the operation of the cooling fan 26 based on requests from the air conditioning request unit 52 and the engine cooling request unit 56. The rotational speed of the cooling fan 26 may be controlled to be higher as the air conditioning load and coolant temperature increase. The rotational speed of the cooling fan 26 may be increased in stages as the air conditioning load and coolant temperature increase. When the operation of the cooling fan 26 is not requested, it can be assumed that the cooling fan 26 is to be stopped.

[0018] When the refrigeration cycle is operating at low load, the refrigerant cannot absorb enough heat in the evaporator 22. As a result, at the outlet of the evaporator 22, the refrigerant may not completely evaporate, leaving a liquid phase and resulting in a gas-liquid two-phase state. When the refrigerant drawn into the compressor 16 is in a gas-liquid two-phase state, the compression efficiency of the compressor 16 decreases. Consequently, the temperature of the refrigerant passing through the condenser 18 decreases, and the temperature difference between the refrigerant and the surrounding outside air becomes smaller. As a result, the refrigerant is not sufficiently cooled and some of it does not condense, leaving a gas phase, and the refrigerant may be in a gas-liquid two-phase state at the outlet of the condenser 18. When the gas-liquid two-phase refrigerant is sent to the expansion valve 20, sound is generated when the bubbles pass through the orifice of the expansion valve 20. In addition, the pressure fluctuations when the bubbles pass through the orifice are transmitted through the refrigerant piping 24, and sound may be radiated from the components of the refrigeration cycle circuit 12. To suppress this refrigerant passage noise, when the refrigerant pressure is low due to a low air conditioning load, and when the operation of the indoor unit 14 is one that is likely to generate refrigerant passage noise, the air conditioning request unit 52 requests the cooling fan control unit 54 to stop the operation of the cooling fan 26. The cooling fan control unit 54 operates and stops the cooling fan 26 unless there is another request to operate the cooling fan 26, such as a request to operate it when the engine coolant temperature is high. When the cooling fan 26 stops, the pressure of the refrigerant in the condenser 18 increases, the gas phase decreases or disappears, and the refrigerant passage noise is reduced.

[0019] Figure 2 is a p-h diagram showing the state of the refrigerant in the refrigeration cycle. The refrigerant is pressurized by the compressor 16 (a) and cooled in the condenser 18 (b). If point b crosses the saturated liquid line, the refrigerant is in the liquid phase, and the liquid-phase refrigerant passes through the expansion valve 20. After passing through the expansion valve 20, the refrigerant's pressure drops (c), and it absorbs heat and liquefies in the evaporator 22 (d). If the pressure of the refrigerant is not sufficiently increased by the compressor 16, as shown by the dashed line, the state of the refrigerant does not cross the saturated liquid line (b’), and the refrigerant in the gas-liquid two-phase state is sent to the expansion valve 20. By stopping the cooling fan 26, the refrigerant in the condenser 18 is not cooled and its temperature rises, and as shown by the solid line, the pressure of the refrigerant increases. As a result, the state of the refrigerant crosses the saturated liquid line and becomes the liquid phase (subcooled state), and the refrigerant passage sound can be suppressed.

[0020] Figure 3 is a diagram showing the control of the air conditioner 10 related to suppressing the refrigerant passage sound. The air conditioning demand unit 52 basically demands the operation of the cooling fan 26 while the refrigeration cycle circuit 12 is operating, that is, while the compressor 16 is operating. The control flow for suppressing the refrigerant passage sound shown in Figure 3 is periodically executed while the refrigeration cycle circuit 12 is operating.

[0021] First, it is judged whether the refrigerant pressure is lower than a predetermined value (S100). When the refrigerant pressure is high, in the p-h diagram of Figure 2, since the saturated liquid line is on the right (high enthalpy side), the refrigerant passing through the condenser 18 crosses the saturated liquid line sufficiently and becomes the liquid phase. Therefore, there is no need to stop the cooling fan 26, and the current state (that is, the operation demand) is maintained (S102). When the refrigerant pressure is low (shown by the dashed line in Figure 2), the refrigerant may be cooled only up to before the saturated liquid line in the condenser 18 and become a gas-liquid two-phase state and be sent to the expansion valve 20.

[0022] Next, when the refrigerant pressure is lower than a predetermined value, it is determined whether the operation of the indoor unit 14 is such that refrigerant passage noise is likely to occur. Specifically, it is first determined whether the blower's airflow rate is lower than a predetermined value (S104), and then it is determined whether seating position adaptive control is set (S106). If the blower's airflow rate is low, the amount of heat absorbed by the refrigerant in the evaporator 22 is low, and it may not vaporize sufficiently, leaving a liquid phase. When the compressor 16 compresses the refrigerant in a state where the liquid phase remains, the efficiency is reduced, and the pressure cannot be sufficiently increased. As a result, after passing through the condenser 18, the refrigerant may become a gas-liquid two-phase state, which may generate refrigerant passage noise. Also, when seating position adaptive control is set, the range of air conditioning is limited and the airflow rate is reduced, making it easier for the refrigerant to become a gas-liquid two-phase state. Furthermore, since seating position adaptive control is intended to suppress energy consumption, increasing the rotation speed of the compressor 16 to increase the refrigerant pressure and eliminate the gas-liquid two-phase state in order to suppress refrigerant passage noise goes against that intention. Therefore, when seating position application control is set, the cooling fan 26 is stopped to suppress the refrigerant passage noise.

[0023] When the refrigerant pressure is lower than a predetermined value (S100), the blower airflow rate is lower than a predetermined value (S104), and seat position adaptive control is set (S106), the air conditioning request unit 52 requests that the cooling fan 26 be stopped (S108). The cooling fan control unit 54 stops the cooling fan 26 unless there is an operation request from another unit, such as the engine cooling request unit 56.

[0024] By stopping the cooling fan 26, the amount of heat dissipated by the refrigerant in the condenser 18 decreases, causing the refrigerant temperature to rise, the refrigerant pressure to increase, and the amount of gaseous refrigerant to decrease. This suppresses the generation of refrigerant passage noise that occurs when air bubbles pass through the expansion valve 20. In addition, the power consumption of the cooling fan 26 can be reduced. Furthermore, the noise generated by the cooling fan 26 itself can also be suppressed. [Explanation of Symbols]

[0025] 10 Air conditioning system (HVAC system), 12 Refrigeration cycle circuit, 14 Indoor unit, 16 Compressor, 18 Condenser, 20 Expansion valve, 22 Evaporator, 26 Cooling fan, 32 Heater, 34 Blower, 38 HVAC control device, 52 HVAC request unit, 54 Cooling fan control unit, 56 Engine cooling request unit.

Claims

[Claim 1] A cooling fan control unit that controls the operation of a cooling fan that blows cooling air onto both the condenser of the refrigeration cycle circuit and the radiator that cools the engine coolant, An air conditioning request unit requests the cooling fan control unit to operate the cooling fan based on the operating status of the vehicle's air conditioning system, When the engine coolant temperature exceeds a predetermined value, an engine cooling request unit requests the cooling fan control unit to operate the cooling fan, A control device for a vehicle air conditioning system, including, It is possible to set seating position adaptive control, which reduces the amount of air blown by the blower that supplies temperature and humidity-adjusted air into the vehicle cabin according to the seating position of the occupants. The aforementioned air conditioning request unit is When the refrigerant pressure in the refrigeration cycle circuit of the vehicle air conditioning system is lower than a predetermined value, the airflow rate of the blower is lower than a predetermined value, and the seating position adaptive control is set, the cooling fan control unit is requested to stop the cooling fan. The cooling fan control unit is When the air conditioning request unit receives a request to stop the cooling fan, and there is no request from the engine cooling request unit to operate the cooling fan, the cooling fan is stopped. A control device for a vehicle air conditioning system, characterized by the following features.

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