JPS62241723A - Compressor control method for air conditioner in automobile - Google Patents

Abstract

PURPOSE:To reduce the repetition of on/off so as to improve the operability, in the air conditioning control by means of operating the on/off of the compressor, by employing the variable capacity type compressor and switching the capacity into two steps according to the blow-off temperature in an evaporator. CONSTITUTION:A thermistor 110 for detecting a blow-off air temperature on the downstream side of an evaporator 50 in a clean unit and the detected output is inputted to a variable control circuit 21 and compressor control circuit 11 in an air conditioner amplifier 200. And, according to the blow-off temperature, a variable solenoid 20 and magnet clutch relay 10 are controlled. That is, in the case that the blow-off temperature is less than the first set value T1, the available capacity is, for example, set to be 50%, and in the case that the temperature is moreover lowered to be the second set value T2, the compressor 1 is turned off. Besides, in the case that the temperature rises to be the third set value T3 (T3>T1>T2), the compressor is controlled in such a manner that the available capacity is attained to be 100%.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to an air conditioner for an automobile, and particularly to an air conditioner for an automobile that can air condition the interior of a vehicle without impairing drivability. The present invention relates to a method of controlling a variable capacity compressor.

[Conventional technology]

Generally, there are two methods for controlling the compressor of an automotive air conditioner. The first method uses a thermistor,
It detects the temperature of the air flowing through the evaporator and controls the compressor to turn on and off depending on whether the detected temperature is around a desired temperature and is used for the purpose of power saving. The second method uses the EPR method to control the refrigerant evaporation pressure in the evaporator to control the compressor to be always ON, and is used for the purpose of improving operability. In other words, the former means 100% ON/O operation of the compressor.
The FF operation is repeated, and the latter is 100 times the compressor.
The ON operation of % operation is performed continuously and control is performed using the t=pR method. An example of an air conditioner using a thermistor is disclosed in Japanese Utility Model Application No. 52-115044.

[Problem that the invention seeks to solve]

However, the two conventional methods have the following drawbacks. In other words, in the former (first) method, since the compressor operates at 100%, the frequency of turning the compressor on and off increases, especially during light load operation, and when the compressor is operated at 08:00, the running load suddenly increases. The vehicle will be in a braking state for a moment. Also, conversely, compressor OF! - Sometimes, the load suddenly disappears, and each time the vehicle accelerates momentarily. According to this method, the driver receives a shock every time the compressor is turned on and off, which impairs drivability. It has the disadvantage of being rough. Also, the latter (second) method.

Always turn the compressor on and off! Although there is no shock in drivability due to this, it has the disadvantage of poor fuel efficiency due to the constant compressor load.

[Object of the Invention] An object of the present invention is to provide a method for controlling a compressor of an air conditioner for an automobile, which can improve fuel efficiency and driveability.

[Means for solving problems]

A swash plate type variable capacity compressor is used for the compressor (100%←→50% switching).

Using a thermistor to detect evaporator outlet temperature.

The variable capacity compressor is controlled. This control is
First, the temperature of the air blown from the evaporator decreases, and
When the temperature drops below C, the variable solenoid is activated to operate the compressor at 50% capacity. Next, when the blowing temperature from the evaporator further decreases to Z'C, the compressor is turned off. After that, when the blowout temperature rises and reaches Y''C, turn on the variable capacity compressor at 50% operation.
Even when operating at 0%, the temperature inside the vehicle continues to rise (the load is greater than the cooling power), and when it reaches W''C, the operating capacity of the variable capacity compressor is switched to 100%.
The mutual relationship between Y"C, Z'C, and W'C is W"C>Y'C
, X'C>Z'C. Therefore, during light load operation, the operation is always at 50%.

In this way, one aspect of the present invention detects the evaporator outlet temperature and determines whether the temperature is higher than the second set value of the thermistor temperature or not.
In a device that air-conditions a vehicle interior by turning on and off a compressor depending on whether the temperature is lower than a set value of using a variable capacity compressor, controlling the variable capacity compressor to a small capacity operating state when the evaporator outlet temperature becomes equal to or lower than a third set value lower than the second set value;
The present invention is characterized in that when the evaporator outlet temperature reaches or exceeds a fourth set value that is higher than the second set value, the operating state is controlled to have a large capacity.

〔Example〕

Examples of the present invention will be described below.

FIG. 1 shows an embodiment of the invention.

In the figure, an evaporator 50 in the cooling unit
A thermistor 110 is sunk downstream of the evaporator 5o to detect the temperature of the air blown out from the evaporator 5o.

A variable control circuit 21 and a compressor control circuit 11 in an air conditioner amplifier 200 are connected to this thermistor 110.

This lf variable control circuit 21 switches the variable solenoid 20 of the ηf variable capacity compressor 1 when the temperature detected by the thermistor 110 reaches a predetermined temperature. The compressor control circuit 11 also controls a compressor magnet clutch relay 10 that performs ON-OFt of the compressor 1.

FIG. 2 shows a detailed circuit of the air conditioner amplifier 200 shown in FIG. 1.

In the figure, the variable displacement compressor 1 is turned on when the engine speed is above a predetermined speed.

It is turned off when the rotation speed is below a predetermined number. The variable capacity compressor 1, which is controlled on and off in this manner, further raises and lowers the room temperature, that is, when the temperature is below a predetermined temperature, it is turned off, and when the temperature is above a predetermined temperature, it is turned on.

Further, in the present invention, the variable solenoid 20 is controlled to be turned on at temperatures below X°C and turned off at temperatures above W'C, thereby achieving stable cooling.

The breaker point 3 as a rotation detector is connected to a battery 5 via an ignition coil 4, and a capacitor 6 is provided between its quantity terminals. The breaker point 3 is repeatedly turned on and off in proportion to the engine speed N, and a predetermined pulse signal is generated between both terminals thereof.

This pulse signal is input to the rotation speed detection circuit 7, which generates a voltage that is inversely proportional to the frequency of the pulse signal, that is, inversely proportional to the engine rotation speed N. That is, the rotation speed detection circuit 7 includes transistors 70, 71,
Diode 72, capacitors 73, 74, 75, resistor 7
6.77.78°79.80,81,82,83,84
, 85°86. Therefore, the pulse signal is input to the base of the transistor 70 via the resistors 76, 77 and the capacitor 73, and a predetermined ON/OFF output is generated at the collector of the transistor 70. The transistor 71 is turned on and off in response to this turning on and off, and in response to this, the charging potential of the capacitor 75 on the collector side is controlled. The charging potential of the capacitor 75 is inversely proportional to the engine speed N, that is, it is at a low potential when the engine speed N is high. The charging potential of this capacitor 75 is outputted from a resistor 85.

The voltage across resistor 85 is input to relay drive circuit 9.

This relay drive circuit 9 is turned on and off depending on the voltage value, and the compressor, magnetic clutch, and relay 1
Activate 0. This relay drive circuit 9 is a transistor 9
0.91, a capacitor 92, and a resistor 93.94. The voltage output of resistor 85 is input to the base of transistor 90.

The transistor 90 is turned on and off depending on this voltage value. In response to this on/off operation.

Although the transistor 91 is turned on and off, there is a predetermined hysteresis relationship with the engine speed N. That is, when the engine speed N is above the predetermined value N2, the transistor 91 is turned on, and when it is below the predetermined value N1, the transistor 91 is turned off. This predetermined value N, N2
There is a relationship of N2>N, and both are determined based on idling rotation. An excitation coil 10A of a compressor/magnetic clutch/relay 10 is connected with a diode 100 to the collector of the transistor 91 which operates on and off in this manner. Excitation coil IO
A is excited when the transistor 91 is turned on, and the relay contact 10B is turned on.

The variable capacity compressor 1 is connected to the battery 5 via a relay contact 10B, is activated by turning on the relay contact 10B, and is deactivated by turning off the relay contact 10B. This variable capacity compressor 1 and engine speed N
Similar to the activation and deactivation of the transistor 91, the relationship between the transistor 91 and the transistor 91 is such that the transistor 91 is activated when the voltage is equal to or higher than a predetermined value N2, and is activated when the voltage is equal to or lower than the predetermined value N2. The reason why the rotational speed N for ON operation and OFF operation is different like Ni and N2 is as follows.
It slows down the response due to fluctuations in engine speed N, causes the relay contact 10B to fluctuate, and causes the variable displacement compressor 1 to turn on and off.
This is to prevent wear and tear caused by frequent repeated off-operations. Note that the diode 101 arranged in parallel with the relay drive circuit 9 is inserted to prevent malfunctions of the relay drive circuit 9 and rotation detection circuit due to surges. Also, the engine rotation speed N at which the transistor 90 is turned on and off is
, N2 can be adjusted by adjusting the resistance 84.

The above-described operation of the variable capacity compressor 1 is controlled by turning on the control circuit 11 as the room temperature rises and falls.

It can also be done by turning off the output. In this embodiment, this on/off control is performed by a relay drive circuit 9 and a control circuit 11. The control circuit 11 includes a thermistor 110,1
11, transistor 112゜113.114, Zener diode 115. Capacitors 116, 117. resistance 11
8,119°120.121,122,123,124
It is composed of ゜125, 126, 127, 128, 129゜130. The thermistor 110 is used to detect room temperature (detects the temperature of the air discharged from the evaporator 50), and its internal resistance changes in inverse proportion to the rise and fall of the room temperature. Therefore, when the room temperature reaches the predetermined value t2, the 1-transistor 112 is turned off, and the transistor 11 is thereby turned off.
Since the transistor 3 is turned on, the transistor 114 is turned off. On the contrary, when the room temperature becomes lower than the predetermined value t1 during processing, the operations of the transistors 112, 113, and 114 are completely reversed.

In this way, the room temperature t for ON and OFF operation of the control circuit 11 is different, such as tz (where tz>tt), depending on the engine rotation speed N1. It is for the same reason that N is different.

In this way, the transistor 114 is turned on and off in accordance with the rise and fall of the room temperature, and the operation of the transistor 114 is similar to that of the transistor 90 in the relay drive circuit 9. However, transistor 9
In contrast to 1, the presence of transistor 90 and transistor 114 turns off transistor 91 even if either one is turned on, so 1-transistor 91 turns on and off as transistors 1-114 turn on and off. This occurs only when the engine rotational speed N, at which the 1-transistor 90 is in the OFF operating state, is equal to or higher than the predetermined value N2. Therefore, at this time, the operation of the variable capacity compressor 1 is controlled as the room temperature rises and falls.

Note that the Zener diode 115 of the control circuit 11 is for constant voltage, and the thermistor 111 is inserted for temperature compensation.

In addition, the variable capacity compressor 1 has its capacity (100%
, 50%) is controlled by the variable control circuit 21. This variable control circuit 21 is.

It is composed of a transistor 210, resistors 211 and 212, and a variable resistor 213. The indoor temperature (temperature detected from the thermistor 110) rises to a predetermined value (W'C)
When the voltage becomes OFF, the transistor 210 turns OFF FL, and the variable solenoid 20 turns OFF. As a result, the operating capacity of the variable displacement compressor 1 becomes 100%. Conversely, when the room temperature decreases and becomes below a predetermined value (x"c), the transistor 210 turns ONL, and the variable solenoid 2
0 is ON, and the operating capacity of variable capacity compressor 1 is 50.
% operation.

For the variable capacity compressor 1 controlled in this way,
A blower motor 2 is provided to send cool air into the room. The blower motor 2 is supplied with power from the battery 5 via a rotation changeover switch 12 (hereinafter simply referred to as the switch 12), and the switch 12 can be switched in three stages.

That is, in the blower motor 2, the switch 12 is connected to the contact 12A.
When switched to contact 12B, battery 5 is directly supplied with power, and when switched to contact 12B, battery 5 is connected to resistor 12.
When the contact 12C is switched, the battery 5 is supplied with power through the resistor 120°121. In other words, the contacts 12A, 12B
, 12C, the number of revolutions of the blower motor 2 decreases in the order of 12C, and the maximum amount of cold air is blown out when the contact 12A is switched.

Switch 1 for switching the rotation speed of this blower motor 2
2 is provided with a temperature adjustment circuit 14 for lowering the cut point of the variable capacity compressor 1 during rotation. This temperature adjustment circuit 14 includes transistors 140, 14
1, a capacitor 142, and resistors 143, 144, and 145. The resistor 145 is connected in parallel to the thermistor 110 via a transistor 141. That is, the transistor 140 is turned on when the switch 12 is switched to the contacts 12B and 12G, but the transistor 140 is turned on when the switch 12 is switched to the contacts 12B and 12G;
Since it is turned off when switched to 2A, the transistor 141 is turned on when it is turned off. When this transistor 141 is turned on, a resistor 145 is connected in parallel to the thermistor 110, so that the resistance value between both terminals of the thermistor 110 is substantially reduced. here.

If the resistance value of the thermistor 110 when the thermistor 110 and the resistor 145 are not connected in parallel is R, then when the thermistor 110 and the resistor 145 are connected in parallel, in order for the combined resistance between both terminals to be the value R, Further, as the room temperature decreases, the internal resistance of the thermistor 110 must increase. Therefore, by selecting a predetermined value for the resistor 145 and the transistor 141 connected in parallel, the on/off operating point of the control circuit 11, that is, the cut temperature (tt, tz) of the variable capacity compressor 1 can be set to (tt to -1,
-11, however, it can be lowered to tO>O).

This makes it possible to further reduce the temperature of the cold air when the blower motor 2 rotates at its maximum speed, thereby enabling powerful cooling.

The above circuits are operated by turning on the power switch 15, which is connected to each circuit 7, 9, 11.
is inserted into the ground side circuit.

A switch provided adjacent to this switch 15 is a town switch 16, which forcibly sets the charging potential of the capacitor 75 of the rotation detection circuit 7 to zero level by turning on the town switch 1G. This town switch 16 is for forcing the variable capacity compressor 1 into an operating state as required for cooling when the engine speed N decreases. As described above, even if the charging potential of the capacitor 75 turns on the transistor 90, the charging potential is brought to zero level by turning on the town switch 16, and the transistor 90 is turned off, so that the transistor 91 is turned on. It is turned on and the compressor 1 is operated. At this time, the engine rotational speed N is increased by means not shown.

〔Effect of the invention〕

As explained above, according to the present invention, as shown in FIG. 3 A, compared to the conventional temperature control characteristic B, the number of repetitions of the compressor turning ON and OFF is reduced, and the operational feeling is improved. can do.

Further, according to the present invention, since the number of repeated ON/OFF operations of the compressor is reduced, the durable life of the magnetic clutch can be greatly improved.

Further, according to the present invention, since there is a temperature range in which the compressor operates at 50%, the load on the engine can be made lighter than in conventional devices, and fuel efficiency can be improved.

As described above, according to the present invention, it is possible to improve fuel efficiency and drivability.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram showing an embodiment of the present invention, FIG. 2 is a detailed circuit diagram of the embodiment shown in FIG. 1, and FIG. 3 is a temperature control characteristic diagram. DESCRIPTION OF SYMBOLS 1... Variable capacity compressor, 20... Variable solenoid, 21... Variable control circuit, 110... Thermistor.

Claims (1)

[Claims] (1) In a system that detects the evaporator outlet temperature and turns on and off the compressor depending on whether the temperature is higher than the second set value or lower than the first set value of the thermistor temperature to air condition the vehicle interior, the compressor A variable capacity compressor having a capacity that can be switched into two stages and equipped with a variable solenoid for switching the capacity between the two stages is used, and the variable capacity compressor is operated at a temperature where the evaporator discharge temperature is lower than the second set value. When the evaporator outlet temperature becomes equal to or lower than the third set value, the operating state is controlled to a small capacity, and when the evaporator outlet temperature becomes equal to or higher than the fourth set value, which is higher than the second set value, the operating state is controlled to a large capacity. A method for controlling a compressor of an air conditioner for an automobile, characterized in that the compressor is controlled to be in an operating state.