JPS59112156A - Method of controlling compressor for air-conditioning of car - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION In particular, the present invention relates to a method of controlling the capacity of a compressor based on the pressure or temperature on the discharge side of the compressor, or the temperature of engine cooling water.

Generally, if the pressure or temperature on the discharge side of a compressor becomes abnormally high or abnormally high, there is a risk that the compressor may seize. Further, the temperature of the engine cooling water becomes high, and if the compressor is used for a long time in this state, the load on the engine increases, so there is a risk that the temperature of the cooling water becomes even higher and overheating occurs.

Therefore, a safety device has been devised that controls the compressor based on a signal from a sensor that detects the pressure or temperature on the discharge side of the compressor or a sensor that detects the temperature of the engine cooling water. This safety device is known to consist of a temperature fuse, but this has the drawback that when the fuse blows out, it takes time to replace it, and air conditioning performance is significantly impaired during this time. Additionally, there is a known switch circuit that detects the pressure or temperature on the discharge side of the compressor or the temperature of the engine cooling water and turns off the compressor when the pressure or temperature exceeds a set level. According to the above, when the compressor is turned off due to the switching circuit, no cooling is performed at all, and as described above, the air conditioning performance is impaired.

The purpose of the present invention is to gradually reduce the capacity of one compressor when the pressure on the discharge side of the compressor, the temperature of the compressor, or the temperature of the engine cooling water rises above the set level 6. The above-mentioned drawbacks are eliminated by lowering the temperature of the cooling water and reducing the load on the engine. 1 is a block diagram showing an example of a control method for a vehicle air conditioning compressor according to the present invention. In the figure, air introduced from an outside air port 1 and an inside air port 2 is controlled by an inside/outside air switching door 3, and the door 3 is controlled by an actuator 4. Driven. Air introduced from the inside/outside air switching door 3 side is sent toward the evaporator 6 by the blower 5, and is further sent toward the heat core 7 side. After the mixing ratio of the cold air cooled by the evaporator 6 and the warm air heated by the heater core 7 is adjusted by the air mix door 8,
The air is blown out from the head outlet 9, the foot outlet 10, or the defrost outlet 11. Each of the above air outlets 9, 1
The distribution of air blown out from the 0.11 is controlled by mode switching doors 12.13, which are driven by actuators 14.15. The air mix door 8 is driven by an actuator 16.

17 is a control device, which includes an inside/outside air switching door control section, a blower control section, a compressor control section, an air mix door control section,
It is equipped with a mode switching control section, and calculates and processes the set temperature signal T from the temperature setting device 18, the inside air temperature signal tr from the vehicle interior temperature sensor 19, the outside air temperature signal ta from the outside air temperature sensor 20, etc. Each of the above actuators 4
14, 15, 16, blower 5, electromagnetic clutch 21, etc.

The compressor control section in the control device 17 outputs an H level signal when the pressure on the discharge side of the compressor nozzle detected by the discharge pressure sensor 30 becomes higher than a set level P, as shown in FIG. 2, for example. A comparator 31, a comparator 33 that outputs an H level signal when the temperature on the discharge side of the compressor detected by the temperature sensor 32 becomes higher than a set level C8, and a temperature detected by the engine coolant temperature sensor 34 are set. It is composed of a comparator 35 that outputs an H level signal when the level becomes higher than the level ES. These sensors 3
0, 32.34 and comparators 31, 33.35 constitute abnormality determining means. Each comparator 31, 33.3
The signal from 5 is led to the input terminal of OR circuit 36. The output signal of the OR circuit 36 is supplied to the capacity control section 37.

The capacity control unit 37 controls the capacity variable mechanism 39 of the compressor 38 based on the output signal from the OR circuit 36 or the target value S.
control. The variable capacity mechanism 39 is composed of a solenoid valve provided in a bypass section between the refrigerant outlet of the compressor and the refrigerant inlet of the compressor, and the amount of refrigerant fed back from the refrigerant outlet to the refrigerant inlet side by controlling this solenoid valve. can be controlled. Thereby, the amount of refrigerant supplied from the discharge port can be controlled, and the capacity of the compressor can be substantially controlled. Alternatively, in the case where the compressor is a swash plate type compressor, the variable capacity mechanism 39 may include a mechanism that controls the inclination angle of the swash plate or a mechanism that controls the pulley ratio of the pulley that transmits rotational force to the compressor. It's okay. Note that the compressor 38 is equipped with a capacitor 40. An expansion valve 41 and the like are connected to constitute a refrigeration cycle 42. In addition,
The timer 50 is driven by the capacity control section 37 and outputs a signal N after a set time T has elapsed.Next, the operation of the method for controlling a vehicle air conditioning compressor according to the present invention will be described with reference to FIG. First, in a normal control state, the capacity control section 37 receives the set temperature signal To from the temperature setting device 18.

The variable capacity mechanism 39 is controlled based on the magnitude of the target value S obtained by calculating the signal tr from the indoor hot water temperature sensor 19 and the signal ta from the outside temperature sensor 20. That is, it is determined whether the capacity of the compressor is set to the target value S, and if it is set to the target value, the compressor capacity is maintained as it is, and if it is not set to the target value S, the compressor capacity is It is determined whether the capacity of the compressor is smaller than the target value S, and if it is smaller than the target value S, the variable capacity mechanism 39 is controlled to increase the capacity of the compressor by one step. When the capacity of the compressor is larger than the target value, the capacity of the compressor is set to be smaller so that the capacity becomes equal to the target value. Through such normal control, the capacity of the compressor is determined by the signals TT), tr,
It is controlled based on the magnitude of the target value S determined by ta.

Here, due to some cause, the pressure on the discharge side of the compressor becomes higher than the set level, or the temperature on the discharge side of the compressor becomes higher than the set level, or the temperature of the engine coolant becomes higher than the set level, and the comparator 31
, 33, 35 is inverted from the L level to the H level, an H level signal is supplied from the OR circuit 36 to the capacitance control section 37, so the capacitance control section 37 first It is determined whether the compressor 38 is off based on a signal from a compressor operation detection means (not shown). If the compressor is off, the state is maintained, but if the compressor is on, the capacity of the compressor is determined based on a signal from a capacity detection means (not shown), and the capacity of the compressor is already the minimum capacity. If so, turn off the compressor. If the capacity of the compressor is not the minimum capacity, the capacity of the compressor is reduced by one step by controlling the variable capacity mechanism 39 (FIG. 4S). At this time, the capacity control section 37 clocks the timer 5o and drives the timer 50. Here, the capacity control unit 37 determines whether the pressure on the discharge side of the compressor, the temperature on the discharge side, or the temperature of the engine cooling water are at the set level, that is, whether the output of the OR circuit 36 is at the H level or the L level, If the level is reached, the set time T has elapsed and the timer 50 sends the signal N, and the compressor capacity is reduced by one step again (
Figure 4 32). In this way, if an abnormality occurs in the compressor or the temperature of the engine cooling water rises to an abnormal temperature, the capacity of the compressor will be reduced until the abnormal condition is resolved or the temperature of the engine cooling water drops to normal temperature. It is set smaller in steps. Due to such control, when the pressure or temperature on the discharge side of the compressor becomes lower than the set level, or the temperature of the engine cooling water becomes lower than the set level, and the output of the OR circuit 36 becomes L level, the capacity control section 37 controls the variable capacity mechanism 39 based on the magnitude of the target value S to perform normal control.

Therefore, according to the present invention, when the pressure on the discharge side of the compressor or the temperature on the discharge side or the temperature of the engine cooling water becomes higher than a set level, the capacity of the compressor is gradually increased step by step so as to become smaller than the set level. Since the compressor is made small, the compressor is operated within a range in which the pressure and temperature on the discharge side of the compressor or the temperature of the engine cooling water do not exceed a set level, and cooling can be performed. Therefore, it is possible to prevent the feeling from being deteriorated due to no air conditioning being performed as in the conventional case. Further, according to the present invention, liquid compression when the compressor is turned on, which tends to occur when the compressor is not used for a long time, can be reduced, and damage to the compressor caused by this can be prevented. In addition,
In the present invention, the capacity of the compressor may not be reduced stepwise, but may be reduced continuously as shown in FIG. 4M.

Further, in this embodiment, the temperature on the discharge side of the compressor is detected and the capacity of the compressor is controlled based on this temperature, but the present invention is not limited to this, and the temperature on the low pressure side of the compressor or the main body of the compressor is Detects the temperature, compares this temperature with the set level, and performs compression.
The capacity of the mesa may also be controlled.

[Brief explanation of the drawing]

1 and 2 are block diagrams showing an embodiment of the method for controlling a vehicle air conditioning compressor according to the present invention, and FIG. 3 is a flowchart for explaining the operation of the method for controlling a vehicle air conditioning compressor according to the present invention. FIG. 4 is a characteristic diagram illustrating its operation. 6... Evaporator, 7... Heater core, 8...
Air mix door, 17... Control device, 18... Temperature setting device, 19... Vehicle interior temperature sensor, 20... Outside air temperature sensor, 30... Pressure sensor, 32... Compressor temperature sensor , 34... Engine cooling water temperature sensor, 37... Capacity control unit, 39... Capacity variable mechanism,
50...timer.

Claims (1)

[Claims] The pressure on the discharge side of the compressor or the temperature of the compressor or the engine cooling water temperature is compared with the set level, and when it is determined that the pressure is above the set level, the variable compressor capacity mechanism is controlled until the pressure falls below the set level. A method for controlling a compressor for vehicle air conditioning, characterized in that the capacity of the compressor is gradually reduced.