JPH0336689B2 - - Google Patents

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a vehicle air conditioner, and particularly to a vehicle air conditioner that reduces the operating rate of a compressor when the vehicle accelerates or climbs a hill. .

[Conventional technology]

Conventionally, a vehicle air conditioner includes an evaporator, a heater core, and an air mix door that adjusts the mixing ratio of warm air and cold air. When the temperature on the evaporator side detected by the evaporator falls to the OFF setting level, the compressor is turned OFF, and when the temperature rises to the ON setting level, the compressor is turned ON. The compressor is turned on and off to maintain the temperature.

However, such compressor control is performed uniformly when the vehicle is accelerating, decelerating, and traveling at low speed. Therefore, the compressor may be turned on during acceleration or when climbing a slope, and at this time a large load is placed on the engine, making it impossible to smoothly accelerate or climb a slope.

Therefore, when accelerating and climbing a hill using a pressure switch that detects the pressure in the engine intake pipe of a conventional vehicle, a thermostat that controls the compressor on and off compares the temperature detected by the temperature sensor with a reference level. A method has been proposed in which the operating level of a switch circuit is changed for a predetermined period of time to reduce the engine load during acceleration or hill climbing. (Tokugansho
57-156442, etc.) [Problems to be Solved by the Invention] However, according to this method, the operating level of the thermoswitch circuit returns to the normal level after a predetermined period of time has elapsed, so that acceleration or hill-climbing operation may not continue for more than a predetermined period of time. If this continues, a new load will be added to the engine, which poses the problem of worsening hill-climbing drivability.

The present invention has been made in order to eliminate the above-mentioned drawbacks, and its purpose is to provide an air conditioner for a vehicle that can save power when accelerating or climbing a slope, and can maintain good drivability. It is in.

[Means to solve the problem]

The present invention has a timer circuit equipped with a time limit setting circuit and a level adjustment means, and if the acceleration state or hill-climbing state continues after a predetermined period of time has elapsed, the thermoswitch circuit is turned off until such driving state ends. The above objective is achieved by varying the operating level.

〔Example〕

Hereinafter, the present invention will be explained in detail based on Examples.

FIG. 1 is a circuit diagram showing one embodiment of the present invention, and FIG.
The figure is its functional block diagram.

In each figure, 1 is a cooling switch connected to the power source E, and 2 is a pressure switch that detects the pressure in the intake pipe of the engine (it may also be a switch that detects the amount of accelerator pedal depression). Based on the fact that the pressure in the intake pipe increases in the direction of atmospheric pressure and this pressure increases to the set level.
This is the switch that turns ON, and this pressure switch 2
The output from is inverted by the load detection circuit 3,
As a result, as shown in FIG. 2a, a signal that is at H level while the switch 2 is on is output, which is differentiated by the differentiating circuit 4 and supplied as a trigger pulse to the timer circuit 5. supplies an output signal with a constant pulse width to the thermoswitch circuit 6 based on the trigger pulse from the differentiating circuit 4 as a rise detection means, and changes the operating level of the thermoswitch circuit 6. The thermoswitch circuit 6 turns on and off the magnetic clutch 7 based on the output from a temperature sensor 8 that detects the temperature on the evaporator side, thereby controlling the compressor. Above load detection circuit 3
is a series circuit of a resistor 9 and a resistor 10, one end of which is connected to the cooling switch 1 and the other end of which is connected to the pressure switch 2 side, a transistor 11 whose base side is connected to the connection point of this series circuit, and this transistor. It consists of a capacitor 12 connected to the base side and emitter side of the transistor 11, and a resistor 13 connected between the collector side and the ground side of the transistor 11. Based on the pressure switch 2 being turned on, the capacitor 12 is charged through the resistor 10 and the switch 2, and the base of the transistor 11 becomes a low voltage, turning on the transistor 11, which creates a voltage V between the transistor 11 and the resistor 13.
1 occurs. The differentiating circuit 4 includes a capacitor 1 whose one end is connected to the collector side of the transistor 11 and the other end is connected to the anode side of the diode 14.
5, this capacitor 15 and the above diode 14
Diode 1 for negative pulse absorption, whose cathode side is connected to the connection point with and whose anode side is grounded.
The voltage V1 is differentiated by the differentiating circuit 4 and sent to the timer circuit 5 as a trigger pulse. The timer circuit 5 has a time limit setting circuit 100, and the time limit setting circuit 100 includes an operational amplifier 17, a capacitor 18 connected to the inverting input side of the operational amplifier 17, and a resistor 19 connected to the non-inverting input side of the operational amplifier 17. A diode 20 connected in parallel to the capacitor 18, a resistor 21 connected between the output side and the inverting input side of the operational amplifier 17, and a diode 22 and a resistor connected in parallel to the resistor 21. 23, a resistor 24 connected between the output side and the non-inverting input side of the operational amplifier 17, and resistors 25 and 26, and further connected to the output of the differentiating circuit 4. 27. The timer circuit 5 also includes a D-type flip-flop 28 whose data input terminal D is connected to the output of the cooling switch 1 and whose clock input terminal CP is connected to the output of the differential circuit 4.
The level adjusting means 101 is comprised of a NOR gate 29 which supplies a NOR signal between the voltage V1 of the load detection circuit 3 and the output of the operational amplifier 17 to the clear input terminal CL of the flip-flop 28.

In a timer circuit with such a configuration, when the pressure switch is turned on, a pulse as shown in Figure 2a is output from the load detection circuit 3 during this ON time, and then in synchronization with the rising timing, a pulse as shown in Figure 2b is output. Differential pulses as shown are output from the differentiating circuit 4. Then, this differential pulse is sent to the time limit setting circuit 10.
Since it is supplied to the non-inverting input of the operational amplifier 17 through the resistor 27 at 0, the non-inverting input level becomes high and its output is inverted from the L level to the H level. Since the capacitor 18 is charged through the inverting input and the inverting input becomes large, its output is restored to the L level. At this time, the charge in the capacitor 18 is discharged via the diode 22 and the resistor 23 (with a small resistance value). In addition,
The diode 20 is for limiting the potential on the capacitor 18 side to a constant value. Therefore, from the time limit setting circuit 100, the time constant (set time T) shown in FIG.
The operational amplifier 17 sends out a pulse as shown in FIG.

On the other hand, the differential pulse outputted from the differentiating circuit 4 is supplied to the clock input terminal of the flip-flop 28 of the level adjusting means 101. As a result, the flip-flop 28 is set in synchronization with the generation timing of the differential pulse, and its Q output becomes "H" level. During this H level, the non-inverting input of the operational amplifier 30 is amplified to increase the OFF setting level and the ON setting level by a certain value.

By the way, the clear input terminal CL of the flip-flop 28 is held at the "L" level by the output of the NOR gate 29 when either the output of the operational amplifier 17 or the output of the load detection circuit 3 is at the "H" level. Ru. In other words, the flip-flop 28 is reset when the outputs of both the operational amplifier 17 and the load detection circuit 3 become "L" level. As a result, the off setting level and the on setting level are restored to their original levels.

Therefore, if the pressure switch 2 is turned off after the time T has elapsed after the start of acceleration, the flip-flop 28 is reset at this point. In other words, if the acceleration time is shorter than T time, Fig. 2 d
The pulses shown in are the Q of flip-flop 28.
Sent from output. However, if the pressure switch 2 remains ON even after time T has elapsed, the clear input terminal of the flip-flop 28 is held at the "L" level, so its Q output is as shown in Figure 3d. While the pressure switch 2 is in the ON state, it is at the "H" level. In addition, Fig. 3 a to c
correspond to the signals in FIGS. 2a to 2c, respectively.

The output of the flip-flop 28 of the level adjusting means 101 is supplied to the thermoswitch circuit 6. The thermo switch circuit 6 includes an operational amplifier 30
And, the output of this operational amplifier 30 turns ON,
The connection point between the temperature sensor 8 and the resistor 32 is connected to the inverting input side of the operational amplifier 30 via a resistor 33, and the non-inverting input side of the operational amplifier 30 is A connection point between resistor 34 and resistor 35 is connected via resistor 36. A resistor 37 is connected between the output side and the non-inverting input side of the operational amplifier 30, and the output from the flip-flop 28 is supplied to the non-inverting input side of the operational amplifier 30 via the resistor 38. . A variable resistor 39 is connected to the resistor 35, and by adjusting the variable resistor 39, the magnitude of the reference voltage V2 obtained at the connection point between the resistors 34 and 35 can be adjusted. The output of the operational amplifier 30 is supplied to the base side of the transistor 31 from the connection point between the resistors 40 and 41.
One end of the magnetic clutch 7 for controlling the compressor is connected to the connection point between the transistor 31 and the protection diode 42 of the transistor 31, and the other end is grounded. The thermoswitch circuit 6 is configured such that when the temperature of the surface of the evaporator or its vicinity increases, the resistance of the temperature sensor 8 consisting of a thermistor decreases.
Since the output voltage V0 becomes larger, the output of the operational amplifier 30 as a comparator becomes L level, which turns on the transistor 31, so that the compressor is turned on via the magnetic clutch 7. Furthermore, when the temperature on or near the surface of the evaporator decreases, the resistance of the temperature sensor 8 increases, so the output voltage V0 decreases, and as a result, the output of the operational amplifier 30 becomes H level, so the transistor 31 turns OFF.
This turns the compressor off. Therefore, by setting the reference level V2 to a desired value, the ambient temperature of the evaporator can be controlled within the range of the set value.

Incidentally, the output of the flip-flop 28 is supplied to the non-inverting input of the operational amplifier 30 via a resistor 38. Therefore, the input level of the non-inverting input is raised while the flip-flop 28 outputs an "H" level output.

In other words, the reference level for turning on the compressor is raised. Therefore, even if the ambient temperature of the evaporator rises above normal, the transistor 31
will not turn on, and the compressor will not be driven.
That is, the compressor is not driven while the timer time T continues or while the pressure switch 2 is ON, even if the ambient temperature of the evaporator rises above the normal set temperature. This reduces the load on the engine and allows smooth acceleration.

FIG. 4 is a flowchart showing an overview of the operation explained above.
operation level is set to low level (step
50). After that, if pressure switch 2 is turned on,
The operating level of the thermoswitch circuit 6 is raised to a high level (step 52), and it is further determined whether this state has elapsed for a predetermined time (T) (step 52).
53) Then, after the predetermined time (T) has elapsed, the state of the pressure switch 2 is determined again (step 54), and if the pressure switch 2 continues to be ON, the operating level of the thermoswitch circuit 6 is remains at a high level. However, if the pressure switch 2 is OFF, the operating level of the thermoswitch circuit 6 is returned to the original low level (step
55). Such operations are always performed.

Therefore, when accelerating or climbing a hill, the compressor
When the engine is turned on, a new load is added to the engine, which does not impair drivability, and it is possible to save power.

〔Effect of the invention〕

As is clear from the above description, the present invention has a timer circuit equipped with a time limit setting circuit and a level adjustment means, so that it is possible to save power of the engine during acceleration and when climbing hills. This has the effect of improving drivability.

[Brief explanation of the drawing]

Figure 1 is a circuit diagram showing one embodiment of the present invention, Figure 2 is a circuit diagram showing an embodiment of the present invention.
3 and 3 are time charts for explaining the operation, FIG. 4 is a flowchart showing an overview of the operation, and FIG. 5 is a functional block diagram in which the circuit of FIG. 1 is simplified. 1...Cooling switch, 2...Pressure switch, 3
... Load detection circuit, 4 ... Differential circuit (rise detection means), 5 ... Timer circuit, 6 ... Thermoswitch circuit, 7 ... Magnetic clutch, 8 ... Temperature sensor, 100 ... Time limit setting circuit, 101...Level adjustment means.

Claims (1)

[Claims] 1. A thermoswitch circuit that detects the temperature on or near the surface of the evaporator, turns off the compressor when the temperature drops to the off setting level, and turns on the compressor when the temperature rises to the on setting level, and a thermoswitch circuit that detects the engine load condition. A load detection circuit to detect, a time limit setting circuit triggered by the output of a rising edge detection means to detect the rise of a signal from this load detection circuit, and either the output of this time limit setting circuit or the output of the load detection circuit. An air conditioner for a vehicle characterized by comprising: a timer circuit having a level adjustment means for increasing the OFF setting level and the ON setting level by a certain value.