JP2000272335A - Air conditioner for vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To aim at improving comfortability and saving power through reduction in a compressor power by providing a variable capacity compressor having a built-in discharge amount adjusting means that can adjust refrigerant intake pressure and an electric expansion valve that can adjust flow rate of refrigerant in accordance with an externally input signal. SOLUTION: An intake pressure from an evaporator 8 to a compressor 10 is uniformly controlled by a control valve housed in a variable capacity compressor 10. Using an electric expansion valve 13, an opening degree is arbitrarily controlled in accordance with an externally input signal. Therefore a refrigerant state in the evaporator 8 can be controlled more appropriately, leading to further improvement of comfortability. During this control, since supply of the refrigerant is reduced by throttling the expansion valve 13, intake pressure is likely to decrease. However, the compressor 10 maintains the intake pressure to reduce discharge amount. Thus, power-saving of the compressor 10 can be achieved.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vehicle cooling system, and more particularly to a vehicle cooling system in which the power consumption of a refrigerant compressor is improved and comfort is improved.

[0002]

2. Description of the Related Art A conventional vehicle cooling system is shown in FIG.
It is configured as shown in FIG. In FIG.
Indicates the entire mechanical components of the vehicle air conditioner, and an inside air inlet 103 is provided on the inlet side of the ventilation duct 102.
An inside / outside air switching damper 105 for controlling the ratio of the amount of air suctioned from the side (introduction amount) to the amount of air suctioned from the outside air inlet 104 (introduction amount) is provided. The inhaled air is
The air is sucked and pressure-fed into the duct 102 by a blower 107 driven by a motor 106. By controlling the motor 106, the amount of air blown by the blower 107 is controlled.

[0003] An evaporator 108 is provided downstream of the blower 107 as a cooler. In the evaporator 108,
A refrigerant circulated in the refrigerant circuit 109 is supplied. The refrigerant is compressed by, for example, a variable capacity compressor 110 and condensed by a condenser 111, and then sent to an evaporator 108 via a receiver tank 112 and a mechanical expansion valve 113. Inhaled into 110. The operation of the compressor 110 can be arbitrarily controlled by the clutch controller 114. As the compressor 110, for example, a swash plate type variable displacement compressor as described in Japanese Patent Publication No. 3-12673 is used, and the angle of the swash plate is adjusted by a suction pressure controller to make the suction pressure almost constant. It can be adjusted.

The cooled air is supplied to each of the outlets 115, 11
6, 117 (for example, DEF, VENT, FOOT outlets) are blown into the vehicle interior. Each outlet 11
5, 116 and 117 have dampers 118 and 11 respectively.
9, 120 are provided. Dampers 118, 119,
120 selects the outlet.

The voltage (rotation speed) of the motor 106 of the blower 107 and the clutch controller 11 of the compressor 110
Reference numeral 4 is controlled based on a signal from a main controller (control device) 121.

The main controller 121 includes a target vehicle temperature set by a vehicle temperature setting device 122, an external air temperature detected by an external air temperature sensor 123, a solar radiation amount detected by a solar radiation sensor 124, and a vehicle internal temperature sensor 1.
25, the vehicle interior temperature detected is input. The target outlet temperature is calculated based on these input signals.

[0007]

In the above-described conventional vehicle cooling system, the refrigerant circuit controls a variable displacement compressor for controlling the suction pressure to be substantially constant and a superheat degree to be substantially constant. Since the system uses a mechanical expansion valve, the degree of cooling of the cooler by the refrigerant sent to the cooler (evaporator) through the expansion valve cannot be externally adjusted. For this reason, the cooling capacity and the dehumidifying capacity of the cooler itself cannot be adjusted, so that the vehicle interior may be dehumidified more than necessary or unnecessary power of the compressor may be required.

An object of the present invention is to make it possible to directly adjust the degree of cooling of a cooler by a refrigerant sent to a cooler in a refrigerant circuit based on an external signal, thereby substantially reducing the cooling capacity and dehumidifying capacity of the cooler itself. It is intended to improve the comfort by directly controlling the compressor, and to reduce the power required for the compressor through the control to save power.

[0009]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, a cooling device for a vehicle according to the present invention comprises: a blower for blowing air into a ventilation duct opened in a vehicle cabin; A cooler that cools air by exchanging heat, and a refrigerant circuit that is provided in a refrigerant circuit that circulates refrigerant through the cooler, adjusts a discharge amount of the refrigerant that is suction-fed, and adjusts a refrigerant suction pressure to a predetermined pressure. And a variable displacement compressor having a built-in discharge amount adjusting means capable of adjusting the flow rate of the refrigerant by an input signal from the outside.

That is, a variable displacement compressor capable of continuously changing the capacity so that the refrigerant circuit for circulating the refrigerant through the cooler keeps the suction pressure at a predetermined value, for example,
It has an electronic expansion valve capable of externally adjusting the flow rate of the refrigerant flowing into the compressor.

In the above device, the temperature of the air at the outlet of the cooler or the temperature between the fins of the cooler is detected, and the opening degree of the expansion valve is adjusted so that the temperature becomes a target value. preferable. It is preferable that the average temperature of the cooler outlet air or the cooler fin temperature is detected as the cooler outlet air temperature or the cooler fin temperature.

Further, there is provided a superheat degree detecting means for detecting the superheat degree of the refrigerant at the outlet of the cooler or a temperature corresponding thereto, and the expansion valve is opened so that the detected superheat degree does not become lower than a predetermined value. It is also possible to adopt a configuration characterized by adjusting the degree.

Further, an outside air temperature detecting means for detecting an outside air temperature, a cooler temperature detecting means for detecting a cooler outlet air temperature or a cooler fin temperature, and a target outlet temperature is calculated from a vehicle heat load and a set vehicle interior temperature. It is also possible to provide a target outlet temperature calculating means for controlling the cooler temperature T so as to satisfy Tice <T, Toc> T, and Tam> T. Here, Tice: cooler frost limit temperature, Toc: target blowing temperature, Tam: outside air temperature.

In the vehicle cooling system according to the present invention, since the expansion valve provided in the refrigerant circuit is an electronic expansion valve whose opening can be arbitrarily adjusted by an external signal, the opening of the expansion valve is changed. By doing so, the refrigerant flow rate changes, and the position where the evaporation of the refrigerant is completed in the evaporator (cooler) changes, so that the average temperature of the cooler outlet air can be changed as necessary. Therefore, it is possible to directly control the cooling capacity and the dehumidifying capacity of the cooler itself, which cannot be performed by the conventional device, and it is possible to improve comfort in air conditioning control. Also, to keep the refrigerant suction pressure at a predetermined value,
In the compressor that performs capacity control, the supply of the refrigerant amount is reduced by restricting the expansion valve, so that the suction pressure tends to decrease in the refrigerant cycle, but the compressor maintains the suction pressure, so the discharge is reduced. Because the capacity is smaller, the power is reduced. Therefore, power saving of the compressor can be achieved at the same time.

[0015]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a device system diagram of a vehicle air conditioner according to one embodiment of the present invention. In FIG. 1, reference numeral 1 denotes the entire mechanical components of the vehicle air conditioner.
An inside / outside air switching damper 5 is provided to control the ratio between the amount of air suctioned from the inside air inlet 3 (introduction amount) and the amount of air suctioned from the outside air inlet 4 (introduction amount). The sucked air is sucked and pressure-fed inside the duct 2 by a blower 7 driven by a motor 6. The control of the motor 6 controls the amount of air blown by the blower 7.

An evaporator 8 as a cooler is provided downstream of the blower 7, and the evaporator 8 is supplied with a refrigerant circulating in a refrigerant circuit (cooler cycle) 9. The refrigerant is compressed by a swash plate type variable displacement compressor 10 as described in, for example, Japanese Patent Publication No. 3-12673, condensed by a condenser 11, and then cooled by a receiver tank 12,
It is sent to the evaporator 8 via the expansion valve 13, and is sucked into the compressor 10 from the evaporator 8. This suction pressure can be controlled to be substantially constant by a control valve built in the variable displacement compressor 10. Reference numeral 14 denotes a clutch controller that controls the operation of the variable displacement compressor 10.

The expansion valve 13 is an electronic expansion valve, and the degree of opening can be arbitrarily controlled by an external signal.

At the outlet of the evaporator 8, an evaporator outlet air temperature sensor 15 for detecting the evaporator outlet air average temperature (cooler outlet air average temperature) is provided. The temperature sensor 15 extends at least in one direction at the outlet of the evaporator, and can detect the average temperature of the evaporator outlet air temperature.

In the present embodiment, the inlet of the evaporator 8 is
Refrigerant temperature T at the evaporator inlet_IRefrigerant temperature sensor
The temperature of the refrigerant at the outlet of the evaporator is
Degree T _OTemperature sensors 17 for detecting the
And based on signals from the sensors 16 and 17,
The superheat degree calculator 18 allows the refrigerant in the evaporator 8 to be superheated.
SH = T_O-T_ICan be calculated as
ing.

The air cooled by the evaporator 8 is supplied to each of the outlets 19, 20, 21 (for example, DEF, VENT, F
The air is blown into the vehicle interior through an OOT outlet. Dampers 22, 23,
24 are provided. The outlet is selected by the dampers 22, 23, and 24.

A signal from the evaporator outlet air temperature sensor 15 and a signal from the superheat degree calculator 18 are input to a main controller 25 as a control device, and are sent to the main controller 2.
5 outputs a signal for controlling the voltage (rotation speed) of the motor 6 of the blower 7 and a control signal to the clutch controller 14.

The main controller 25 includes a target vehicle temperature set by the vehicle temperature setting device 26 and a mode switching means 27 for dehumidification / economy mode switching described later.
, The outside air temperature detected by the outside air temperature sensor 28, the amount of solar radiation detected by the solar radiation sensor 29, and the vehicle interior temperature detected by the vehicle interior temperature sensor 30. Based on these input signals, the target outlet temperature Toc and the like are calculated.

The calculation and control by the main controller 25 are performed, for example, as shown in FIG. The indoor set temperature Ts set by the vehicle interior temperature setting device 26, the indoor temperature detection value Tr detected by the vehicle interior temperature sensor 30, the solar radiation amount detection value R detected by the solar radiation sensor 29, and the outdoor air detected by the outdoor air temperature sensor 28 Inhalation temperature Ta
m, the average evaporator outlet air temperature detection value Pv detected by the evaporator outlet air temperature sensor 15 is input to the main controller 25. In the main controller 25,
The target outlet temperature Toc is calculated by the equation: Toc = Kp (Ts−Tr) + f (Tam, R, Ts). Kp is a predetermined constant.

Using the Toc calculated as described above,
The following calculations and controls are performed. First, when the dehumidification control is selected, control is performed so as to satisfy Sv = Tice, so that the dehumidification ability of the evaporator 8 is maximized. Where Sv
Represents the target evaporator outlet air average temperature. Tice
Indicates the frost limit temperature of the cooler, and controls the outlet air temperature to the limit temperature at which frost does not occur.

Also, when the economy control mode (shown in FIG. 4) is selected, Sv = Toc-a is satisfied when Toc <Tam, and Sv = when Toc> Tam. Control is performed so as to satisfy Tam-b. a and b are predetermined constants.

In order to satisfy the above control state,
The opening A of the electronic expansion valve 13 is calculated by the following equation. A = K1 (Pv−Sv) + K2 · In In = (Pv−Sv) + I_n-1 In the above equation, K1 (Pv−Sv) is a proportional term, K2 · I
n is the integral term and I_{n- 1}Represents the previous In.
K1 is a predetermined proportional constant, K2 is a predetermined integral constant
It is.

However, when the state of the refrigerant at the evaporator outlet becomes wet, the durability of the compressor is significantly impaired. Therefore, it is necessary to maintain the degree of superheat of the refrigerant at the evaporator outlet at a certain level or more. Therefore, at this time, the degree of superheat SH of the refrigerant in the evaporator 8 is calculated by the superheat degree calculator 18 based on the detection signals from the refrigerant temperature sensors 16 and 17 described above, and the signal of the degree of superheat SH is used. More appropriate calculation and control are performed to prevent a decrease in the degree of superheat and, consequently, a wet state. SH
In the case of <5, a calculation such as A = K3 · In In = (SH−5) + I _n−1 is performed, and control is performed so that the degree of superheat SH does not fall below a predetermined limit set value (= 5). It becomes possible. Here, K3 is a predetermined integration constant.

The signal of the opening degree A of the electronic expansion valve 13 calculated in this way is sent to the electronic expansion valve 13, and the opening degree is controlled to the calculated opening degree A.

As described above, in the present invention, by using the electronic expansion valve 13, the opening degree can be arbitrarily controlled by an external signal, and the state of the refrigerant in the evaporator 8 can be more optimally controlled. It becomes possible to control.

The state of the refrigerant in the evaporator 8 can be represented, for example, as shown in FIG. 3. The refrigerant flowing in the gas-liquid two-phase flow from the inlet side forms a superheated region on the outlet side. The smaller the overheated area is, the more evaporator 8
As a result, high-performance driving is performed.

The size of the superheated region can be represented by the above-mentioned average temperature of the air at the outlet of the evaporator. For example, the above-described refrigerant temperature sensors 16 and 17 correspond to the states shown in FIG. From the detection signal,
The average temperature of the refrigerant in the state (1) can be grasped.

By changing the opening degree of the expansion valve 13 to change the position where the evaporation of the refrigerant in the evaporator 8 is completed, the average temperature of the refrigerant in the evaporator 8 changes as shown in FIG. In addition, it is possible to adjust the blowing temperature by the opening degree of the expansion valve.

Therefore, by controlling the opening of the expansion valve 13, the capacity of the evaporator 8 at that time can be optimized, and the comfort can be further improved.

In the present invention, the compressor 1
In order to reduce the zero load, control in the economy mode can be performed according to the conditions at that time, and the opening degree control of the electronic expansion valve 13 can be performed for power saving.

For example, as shown in FIG. 4, the refrigerant temperature is controlled so that the evaporator outlet air average temperature T falls within the ranges of Tice <T, Toc> T, and Tam> T as described above. The control is performed so as to enter the triangular area indicated by the oblique line 4 and the control is performed by reducing the constant value α. For example, as shown in FIG. 2, when Toc <Tam, Sv =
When Toc> Tam, S is set so that Toc-a is satisfied.
The opening of the electronic expansion valve 13 is controlled so that v = Tam-b. In the example shown in FIG. 4, the dehumidification control area is further included in the above area, and has two modes of the dehumidification mode and the economy mode, and can be switched by the mode switching means (switching switch) 27 as necessary. Has become.

In such control, the compressor 10 for controlling the capacity is controlled so that the refrigerant suction pressure is maintained at a predetermined value.
By reducing the expansion valve 13, the supply of the refrigerant amount is reduced, so that the suction pressure tends to decrease in the refrigerant cycle, but the compressor 10 maintains the suction pressure, so that the discharge capacity decreases. So the power is reduced. Therefore, power consumption of the compressor 10 is reduced, and power saving of the compressor 10 can be achieved at the same time.

By the control according to the present invention described above, for example, a characteristic as shown in FIG. 5 is obtained. 5 (A) shows the opening degree of the expansion valve 13, FIG. 5 (B) shows the corresponding power consumption of the compressor 10, and FIG. 5 (C) shows the corresponding characteristics of the average evaporator outlet air temperature. Thus, the characteristics according to the present invention and the conventional characteristics are compared and shown.

As shown in FIG. 5, by appropriately controlling the opening of the electronic expansion valve 13, the power consumption of the compressor 10 can be reduced. More optimal control of the average air temperature at the outlet of the vessel becomes possible.

[0039]

As described above, according to the vehicle cooling system of the present invention, the cooling valve is provided by using an electronic expansion valve whose opening can be arbitrarily adjusted based on an external signal. It is possible to improve comfort by enabling more appropriate control of the air temperature at the outlet of the compressor, and to reduce power consumption by reducing the power consumption of the compressor.

[Brief description of the drawings]

FIG. 1 is an equipment system diagram of a vehicle cooling device according to an embodiment of the present invention.

FIG. 2 is a block diagram illustrating a control example of the device of FIG. 1;

FIG. 3 is an explanatory diagram showing a state of a refrigerant in an evaporator (cooler) in the apparatus of FIG.

FIG. 4 is a characteristic diagram showing an example of dehumidification / economy control according to the present invention.

FIG. 5 is a characteristic diagram showing an example of a result of the control according to the present invention.

FIG. 6 is an equipment system diagram of a conventional vehicle cooling device.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 air conditioner 2 ventilation duct 3 inside air introduction port 4 outside air introduction port 5 inside / outside air switching damper 6 motor 7 blower 8 evaporator as cooler 9 refrigerant circuit 10 variable capacity compressor 11 condenser 12 receiver tank 13 electronic expansion valve 14 Clutch controller 15 Evaporator outlet air temperature sensor 16, 17 Refrigerant temperature sensor 18 Superheat degree calculator 19, 20, 21 Blow outlet 22, 23, 24 Damper 25 Main controller (control device) 26 Vehicle temperature setting device 27 Dehumidification / economy Switching means 28 Outside air temperature sensor 29 Solar radiation sensor 30 Interior temperature sensor

Claims (6)

[Claims] 1. A blower for blowing air into a ventilation duct opened in a vehicle interior, a cooler in the ventilation duct for cooling air by heat exchange with air, and circulating a refrigerant through the cooler. A variable displacement compressor having a built-in discharge amount adjusting means that is provided in the refrigerant circuit, adjusts the discharge amount of the refrigerant that is suction-fed, and can adjust the refrigerant suction pressure to a predetermined pressure, and A vehicle cooling device comprising an electronic expansion valve capable of adjusting a refrigerant flow rate by an input signal. 2. The method according to claim 1, further comprising detecting a cooler outlet air temperature or a cooler fin temperature, and adjusting an opening degree of the expansion valve such that the temperature becomes a target value.
Vehicle cooling system. 3. The cooling device for a vehicle according to claim 2, wherein the cooler outlet air temperature detects an average temperature of the cooler outlet air. 4. The cooling device for a vehicle according to claim 2, wherein the temperature between the cooler fins detects an average temperature of the temperature between the cooler fins. 5. A superheat degree detecting means for detecting a superheat degree of a refrigerant at a cooler outlet or a temperature corresponding thereto, so that the detected superheat degree does not fall below a predetermined value.
The vehicle cooling device according to any one of claims 1 to 4, wherein an opening degree of the expansion valve is adjusted. 6. An outside air temperature detecting means for detecting an outside air temperature, a cooler temperature detecting means for detecting a cooler outlet air temperature or a cooler fin temperature, and a target blow temperature from a vehicle heat load and a set vehicle interior temperature. 6. The target blowout temperature calculating means for calculating the following formula, and controlling the cooler temperature T so as to satisfy Tice <T, Toc> T, and Tam> T. Vehicle cooling system. Here, Tice: cooler frost limit temperature, Toc: target blowing temperature, Tam: outside air temperature.