Control device for vehicle air conditioner

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 a vehicle air conditioning device. [Background technology]

[0002] There is known an air conditioner that adjusts the temperature and humidity in a passenger compartment of a vehicle. The refrigeration cycle circuit of the air conditioner has a condenser that cools the refrigerant circulating in the refrigeration cycle circuit after it is compressed by a compressor. In order to sufficiently cool and liquefy the refrigerant in the condenser, the condenser is cooled by cooling air sent by a cooling fan. The following Patent Document 1 shows an air conditioner that stops the cooling fan when the refrigerant is sufficiently liquefied in the condenser even without cooling by the cooling fan. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2013-136324 A Summary of the Invention [Problem to be solved by the invention]

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

[0005] An object of the present invention is to suppress the generation of refrigerant passing noise. [Means for solving the problem]

[0006] The control device for a vehicle air conditioning system of the present invention requests the stopping of the cooling fan that cools the condenser of the refrigeration cycle circuit when the refrigerant pressure in the refrigeration cycle circuit of the vehicle air conditioning system is lower than a predetermined value and the operation of the indoor unit that supplies temperature and humidity regulated air to the passenger compartment of the vehicle is an operation that is likely to generate refrigerant passing noise that occurs when the refrigerant passes through the expansion valve of the refrigeration cycle circuit. Effect of the Invention

[0007] When the cooling fan stops, the temperature of the refrigerant passing through the condenser of the refrigeration cycle circuit increases, and the refrigerant pressure increases. This reduces or eliminates the gas phase refrigerant, suppressing the generation of refrigerant passing noise. [Brief description of the drawings]

[0008] [Figure 1] 1 is a schematic diagram showing the general configuration of an air conditioning apparatus and its control device according to the present embodiment. [Diagram 2] This is a ph diagram showing the state of the refrigerant in the refrigeration cycle circuit. [Diagram 3] 5 is a flowchart showing control relating to suppression of refrigerant passing noise. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. Fig. 1 is a diagram showing a schematic configuration of an air conditioner 10 for a vehicle. Hereinafter, "air conditioning" will be referred to as "air conditioning". Fig. 1 also shows, in a block diagram, a configuration related to the control of the air conditioner 10 and a configuration related to a cooling device for the air conditioner 10 and an engine (not shown) mounted on the vehicle.

[0010] The air conditioner 10 includes a refrigeration cycle circuit 12 and an indoor unit 14 that sends temperature- and humidity-controlled air into the passenger compartment of the vehicle. The refrigeration cycle circuit 12 includes a compressor 16 that compresses a refrigerant, a condenser 18 that removes heat from the compressed refrigerant to liquefy the refrigerant, an expansion valve 20 that reduces the pressure of the refrigerant through an orifice and expands it, an evaporator 22 in which the expanded refrigerant liquefies and removes heat from the surroundings, and a refrigerant pipe 24 that connects these together to form a flow path through which the refrigerant circulates. The air conditioner 10 further 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 one of the components of the indoor unit 14. The indoor unit 14 may be provided in each of the front and rear seats.

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

[0012] The indoor unit 14 has an evaporator 22, a heater 32, a blower 34 that sends air to the evaporator 22 and the heater 32, and a unit case 36 that houses them. A part of the engine cooling water is sent to the heater 32 as necessary. The blower 34 takes in one or both of the indoor air and the outside air into the unit case 36, and generates an airflow toward one or both of the evaporator 22 and the heater 32. The ratio of the indoor air and the outside air taken into the unit case 36 is adjusted by a door (not shown) provided in the unit case 36. In addition, the amount of air sent to the evaporator 22 and the heater 32 is also adjusted by another door. The evaporator 22 removes heat from the sent air to cool the airflow. In addition, around the evaporator 22, water vapor contained in the cooled air condenses to dehumidify the air. The heater 32 warms the sent air. Air that has passed through one or both of the evaporator 22 and the heater 32 is sent indoors. The indoor air is cooled by sending the air that has passed through the evaporator 22 into the indoor air. The indoor air is heated by sending the air that has passed through the heater 32 into the indoor air. Furthermore, by passing a part or all of the air dehumidified by the evaporator 22 through the heater 32, it is possible to dehumidify the air without lowering the indoor temperature. The air volume of the blower 34 is adjustable. In addition, although the blower 34 is shown in the figure as an axial fan, the blower 34 is not limited to an axial fan and may be a centrifugal fan such as a sirocco fan.

[0013] The air conditioner 10 is capable of detecting the seating positions of occupants and controlling the air conditioning according to the seating positions. This control is referred to as seating position adaptive control. In seating position adaptive control, if the only occupant is the driver, air is blown toward the driver. Also, if an occupant is seated in the passenger seat in addition to the driver, but there is no occupant in the rear seat, air is blown to the front seats and not to the rear seats. By performing seating position adaptive control, unnecessary operation of the air conditioner 10 is suppressed.

[0014] The air conditioning control device 38 controls the air conditioner 10 based on environmental conditions such as the outside air temperature, the room temperature, and the seating position of the occupant, the operating state of the air conditioner 10 indicated by the refrigerant pressure, and the set temperature and seating position application control set by the occupant. The outside air temperature is detected by an outside air temperature sensor 40, and the room temperature is detected by an room temperature sensor 42. The refrigerant pressure is detected by a refrigerant pressure sensor 44 provided in the refrigerant pipe 24 between the compressor 16 and the condenser. The seating position of the occupant is detected by a seating sensor 46 provided in each seat. The seating sensor 46 may be, for example, a pressure sensor, and detects the seating of the occupant based on the pressure generated by the occupant sitting in the seat. The seating sensor 46 does not have to be provided in the driver's seat. The set temperature is set by the occupant using a temperature setting device 48 provided in the instrument panel or the like. The seating position adaptation control is set by the occupant using a seating position adaptation control switch 50 provided on the instrument panel, etc. By operating the seating position adaptation control switch 50, it is selected whether or not the control is to be executed.

[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 rotation speed of the blower 34 based on this. The output of the compressor 16 is controlled by the rotation speed of the compressor 16. Under conditions where the air conditioning load is high, such as when the outside air temperature is high, the indoor temperature is high relative to the set temperature and the difference between them is large, or there are many occupants, the rotation speed of the compressor 16 is increased to circulate a large amount of refrigerant. At this time, the refrigerant pressure detected by the refrigerant pressure sensor 44 becomes high. 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 conditioner 10. The air conditioning request unit 52 sends an operation request for the cooling fan 26 to the cooling fan control unit 54. The air conditioning request unit 52 requests the cooling fan control unit 54 to speed up the rotation of the cooling fan 26 as the air conditioning load increases. do.

[0016] In addition to the request from the air conditioning request unit 52, the cooling fan control unit 54 also receives a request from an engine cooling request unit 56. The engine cooling request unit 56 requests the operation of the cooling fan when the temperature of the engine cooling water detected by the cooling water temperature sensor 58 becomes equal to or higher than 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 cooling fan 26 may be controlled to have a higher rotation speed as the air conditioning load and the coolant temperature increase. The rotation speed of the cooling fan 26 may be increased in stages as the air conditioning load and the coolant temperature increase. When operation of the cooling fan 26 is not requested, it can be considered that stopping of the cooling fan 26 is requested.

[0018] When the refrigeration cycle is operated at a low load, the refrigerant cannot fully absorb heat in the evaporator 22, and therefore the refrigerant may not completely evaporate at the outlet of the evaporator 22, and the liquid phase may remain, resulting in a two-phase gas-liquid state. If the refrigerant drawn into the compressor 16 is in a two-phase gas-liquid state, the compression efficiency of the compressor 16 decreases. As a result, the temperature of the refrigerant passing through the condenser 18 decreases, and the temperature difference between the refrigerant and the outside air around the condenser 18 decreases. Then, the refrigerant may not be sufficiently cooled and part of it may not condense, and the gas phase may remain, resulting in the refrigerant being in a two-phase gas-liquid state at the outlet of the condenser 18. When the refrigerant in a two-phase gas-liquid state is sent to the expansion valve 20, sound is generated when bubbles pass through the orifice of the expansion valve 20. In addition, pressure fluctuations when bubbles pass through the orifice may be transmitted through the refrigerant piping 24, and sound may be emitted from the components of the refrigeration cycle circuit 12. In order to suppress this refrigerant passing noise, when the refrigerant pressure is low due to a small air conditioning load, and when the indoor unit 14 is operating in an operation that is likely to generate refrigerant passing 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 if there is no other request to operate the cooling fan 26, for example, a request to operate 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 passing noise is reduced.

[0019] FIG. 2 is a ph diagram showing the state of the refrigerant in the refrigeration cycle. The refrigerant is pressurized by the compressor 16 (a) and cooled by the condenser 18 (b). If point b is above the saturated liquid line, the refrigerant is in liquid phase, and the liquid refrigerant passes through the expansion valve 20. The pressure of the refrigerant that passes through the expansion valve 20 decreases (c), and the refrigerant absorbs heat and liquefies in the evaporator 22 (d). If the pressure of the refrigerant is not sufficiently increased by the compressor 16, the state of the refrigerant does not exceed the saturated liquid line (b'), as shown by the dashed line, and the refrigerant in a 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 the temperature rises, and the pressure of the refrigerant rises as shown by the solid line. As a result, the state of the refrigerant exceeds the saturated liquid line and becomes liquid phase (subcooled state), and the refrigerant passing sound can be suppressed.

[0020] Fig. 3 is a diagram showing the control of the air conditioner 10 related to suppression of refrigerant passing noise. The air conditioning request unit 52 basically requests operation of the cooling fan 26 while the refrigeration cycle circuit 12 is operating, i.e., while the compressor 16 is operating. The control flow for suppressing refrigerant passing noise shown in Fig. 3 is periodically executed while the refrigeration cycle circuit 12 is operating.

[0021] First, it is determined whether the refrigerant pressure is lower than a predetermined value (S100). When the refrigerant pressure is high, the saturated liquid line is on the right (high enthalpy side) in the pH diagram of FIG. 2, so the refrigerant that has passed through the condenser 18 sufficiently exceeds the saturated liquid line and becomes liquid. Therefore, there is no need to stop the cooling fan 26, and the current state (i.e., operation request) is maintained (S102). When the refrigerant pressure is low (shown by the dashed line in FIG. 2), the refrigerant may be cooled only to the point just before the saturated liquid line in the condenser 18 and sent to the expansion valve 20 in a gas-liquid two-phase state.

[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 the refrigerant passing sound is likely to occur. Specifically, first, it is determined whether the blower airflow rate is lower than a predetermined value (S104), and then it is determined whether the seating position adaptive control is set (S106). If the blower airflow rate is low, the amount of heat absorbed by the refrigerant in the evaporator 22 is small, and the refrigerant may not be vaporized sufficiently, and the liquid phase may remain. When the compressor 16 compresses the refrigerant in a liquid phase state, the efficiency is reduced and the pressure cannot be increased sufficiently. For this reason, after passing through the condenser 18, the refrigerant may become a gas-liquid two-phase state, and the refrigerant passing sound may occur. In addition, when the seating position adaptive control is set, the range in which the air conditioning is performed is limited and the airflow rate is reduced, so the refrigerant is likely to become a gas-liquid two-phase state. In addition, since the seating position adaptive control is intended to suppress energy consumption, it is contrary to the intention to increase the rotation speed of the compressor 16 to increase the refrigerant pressure and eliminate the gas-liquid two-phase state in order to suppress the refrigerant passing sound. Therefore, when the seating position adaptation control is set, the cooling fan 26 is stopped to suppress the refrigerant passing noise.

[0023] When the refrigerant pressure is lower than a predetermined value (S100), the blower airflow rate is less than a predetermined value (S104), and seating position adaptive control is set (S106), the air conditioning request unit 52 requests the cooling fan 26 to 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 released by the refrigerant in the condenser 18 decreases, the temperature of the refrigerant increases, the refrigerant pressure increases, and the amount of gas-phase refrigerant decreases. This suppresses the generation of refrigerant passing noise that occurs when air bubbles pass through the expansion valve 20. It also suppresses the consumption of driving power for the cooling fan 26. Furthermore, it also suppresses the noise generated by the cooling fan 26 itself. [Explanation of symbols]

[0025] 10 air conditioner (air conditioner), 12 refrigeration cycle circuit, 14 indoor unit, 16 compressor, 18 condenser, 20 expansion valve, 22 evaporator, 26 cooling fan, 32 heater, 34 blower, 38 air conditioning control device, 52 air conditioning request section, 54 cooling fan control section, 56 engine cooling request section.

Claims

[Claim 1] A control device for a vehicle air conditioning device, when the refrigerant pressure in the refrigeration cycle circuit of the vehicle air conditioning device is lower than a predetermined value and an operation of an indoor unit that supplies temperature- and humidity-controlled air into a passenger compartment of the vehicle is an operation that is likely to generate refrigerant passing noise that occurs when the refrigerant passes through an expansion valve of the refrigeration cycle circuit, a request is made to stop a cooling fan that cools a condenser of the refrigeration cycle circuit. A control device for a vehicle air conditioning device.

Images