JPS6247733B2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to an air conditioner for a vehicle, and particularly to a vehicle that reduces engine load by turning off a compressor when the engine load increases due to acceleration or climbing of a vehicle. The present invention relates to an air conditioner for use in air conditioning.

Conventionally, in vehicle air conditioners, when the engine load increases due to acceleration or climbing of a hill, this is detected by a pressure switch installed in the engine intake pipe, and the compressor is turned off for a set time using a timer circuit. By turning off the engine, it is possible to accelerate with less load on the engine or to smoothly climb hills.

However, with conventional air conditioners for vehicles, even if the temperature inside the vehicle is still high without being cooled during the initial stage of operation of the compressor, the compressor is turned off when the vehicle accelerates or climbs a slope. As a result, the temperature inside the vehicle cannot be lowered rapidly, resulting in a delay in cool-down and a deterioration of the passenger's feeling.

The purpose of the present invention is to eliminate the above-mentioned drawbacks by preventing the compressor from turning off even when the vehicle accelerates or climbs a slope when the temperature inside the vehicle has not yet fallen below a set level, such as during the early stages of compressor operation. This will be explained in detail below using examples.

FIG. 1 is a circuit diagram showing one embodiment of a vehicle air conditioner according to the present invention. In the figure, reference numeral 1 denotes a cooler switch, which is connected to a power source E. In FIG. 2 is a pressure switch that detects the pressure in the intake pipe of the engine, and is turned ON when the pressure in the intake pipe rises to a predetermined position during acceleration.The signal from this pressure switch 2 is sent to the trigger circuit 3. A trigger pulse from the trigger circuit 3 is sent to a timer circuit 4, and the timer circuit 4 sends a pulse having a predetermined pulse width to the thermoswitch circuit 5 side. The thermoswitch circuit 5 controls a magnetic clutch 7 for controlling the compressor based on a signal from a sensor 6, such as a thermistor, which detects the temperature at or near the surface of the evaporator. The trigger circuit 3 includes a resistor 8 connected between the pressure switch 2 and the cooler switch 1;
One end is connected to the switch 1, and the other end is the resistor 9.
It is connected to the pressure switch 2 side via a capacitor 10 and an operational amplifier 11. A connection point between a resistor 9 and a capacitor 10 is connected to the inverting input side of the operational amplifier 11 via a resistor 12, and a capacitor 13,
It is grounded via a resistor 14. Note that a resistor 15 and a resistor 16 are connected to the non-inverting input side of the operational amplifier 11.
A connection point between the two is connected via a resistor 17, and a feedback resistor 18 is connected to the non-inverting input side. The timer circuit 4 has one end connected to an operational amplifier 20 and an inverting input side of the operational amplifier 20,
A capacitor 21 has its other end connected to the connection point between the resistors 15 and 16, and a resistor 22 has one end connected to the non-inverting input side and the other end connected to the connection point between the resistors 15 and 16. and the above capacitor 2
A diode 23 is connected in parallel to 1 and limits the drop in the inverting input voltage of the operational amplifier 20, a resistor 24 is connected between the inverting input side and the output side of the operational amplifier 20, and a diode 23 is connected in parallel to this resistor 24. and a diode 2 forming a discharge circuit for the capacitor 21.
5 and a resistor 26 in series. The non-inverting input side of the operational amplifier 20 is connected to its output side via a resistor 27, and the signal from the connection point between the capacitor 13 and the resistor 14 is connected to the resistor 28 and the diode. 29. Timer circuit 4 is always at L level, but based on this signal, its non-inverting input is pulled up, so it becomes H level, and this output charges capacitor 21 via resistor 24, and its inverting input rises, so that the set time is exceeded. Press T to restore to L level. Therefore, a pulse having a constant pulse width is sent to the thermoswitch circuit 5 side. The thermoswitch circuit 5 has an operational amplifier 30, and the sensor 6 and the resistor 3 are connected to the inverting input side of the operational amplifier 30.
1 is connected through a resistor 32, and the connection point between resistors 33 and 34 is connected through a resistor 49 to the non-inverting input side of the operational amplifier 30. Note that a resistor 35 is connected in series to the resistor 33,
Further, a variable resistor 36 is connected to the resistor 34, and the resistor 34 is connected to a variable resistor 36.
Reference voltage obtained from the connection point between 3 and resistor 34
V ₁ is supplied via a resistor 49 to the non-inverting input of the operational amplifier 30 , and the magnitude of this reference voltage V ₁ can be varied by adjusting the variable resistor 36 . A diode 37 is connected to the non-inverting input side of the operational amplifier 30 on the output side of the operational amplifier 20.
A resistor 38 is connected between the non-inverting input side and the output side of the operational amplifier 30.
Its output side is connected to a transistor 40 via a resistor 39.
connected to the base side of the In addition, the transistor 40
A resistor 42 is connected between the base and emitter of the transistor 40, and a magnetic clutch 7 for controlling the compressor is connected between the collector side of the transistor 40 and the protection diode 41. 43
is a comparison circuit which is a feature of the present application, and has an operational amplifier 44, and the non-inverting input side of this operational amplifier 44 has a connection point between the resistors 35 and 33 connected to the resistor 4.
The connection point between the sensor 6 and the resistor 31 is connected to the inverting input side of the operational amplifier 5 through the resistor 46, and the output side of the operational amplifier 44 is connected to the cathode side of the diode 47. 47
The anode side of the diode 29 is connected to the anode side of the diode 29. Note that a resistor 48 is connected between the output side and the non-inverting input side of the operational amplifier 44. This comparison circuit 43 compares the output voltage V ₀ of the sensor 6 with the reference voltage V ₂ at the connection point between the resistor 35 and the resistor 33. When the temperature of the sensor 6 is higher than the set level (set by the reference voltage V ₂ ), the resistance value of this sensor 6 becomes smaller, and the output voltage V ₀ becomes larger than the reference voltage V ₂ , so that the operational amplifier 44 The output of the capacitor 13 and the resistor 14 is turned on, and the trigger pulse obtained from the connection point between the capacitor 13 and the resistor 14 is absorbed through the resistor 28 and the diode 47. Also, to explain the operation of the thermoswitch circuit 5, as the temperature on or near the surface of the evaporator gradually decreases, the output voltage _V0 of the sensor 6 gradually decreases, and when this becomes lower than the reference voltage _V1 , the operational amplifier 3
Since the output of 0 becomes H level, transistor 4
0 is turned OFF, and the compressor controlled by the magnetic clutch 7 is turned OFF. In other words, when the temperature on the evaporator side decreases and reaches the off setting level N of approximately 0°C corresponding to the reference voltage _V1 as shown in Figure 2c, the compressor turns off.
It becomes OFF. When the compressor is turned OFF, the temperature on the surface side of the evaporator gradually rises, and when this temperature reaches the ON setting level M, which is approximately 2.5°C higher than the level N, the output of the operational amplifier 30 becomes L level, and the transistor 40 is turned on, which turns on the compressor controlled by the magnetic clutch 7. Therefore, the compressor repeats ON and OFF operations based on the operation of the thermoswitch circuit 5, and the temperature at or near the surface of the evaporator is set to approximately between level N and level M. Note that the difference between the levels M and N is a constant value depending on the values of the resistors 38 and 49 connected to the operational amplifier 30.

When the vehicle accelerates or climbs a hill and the pressure switch 2 is turned on as shown in FIG. As a result, the output of the operational amplifier 11 becomes H level, and this output charges the capacitor 13, causing the capacitor 13 and the resistor 14 to
A trigger pulse is obtained from the connection point with , and this trigger pulse is supplied via a resistor 28 and a diode 29 to the non-inverting input side of the operational amplifier 20 of the timer circuit 4, so that the timer circuit 4 is operated as shown in FIG. As shown in FIG. 3, the pulse width T is supplied to the non-inverting input side of the operational amplifier 30 of the pulse thermoswitch circuit 5 via a diode 37. Based on this input, the voltage on the non-inverting input side of the operational amplifier 30 increases, so its output becomes saturated at the H level, and the transistor 40 is turned off.
The compressor controlled by the magnetic clutch 7 is turned off. That is, during the set time T of the timer circuit 4, the compressor is forcibly set to OFF, and the load on the engine is reduced, allowing the vehicle to accelerate and climb hills smoothly. Based on the above operation, the compressor turns OFF and the temperature on or near the surface of the evaporator gradually rises.If the temperature on or near the surface of the evaporator rises rapidly as shown in characteristic A, the timer is turned off first. The output of circuit 4 is restored to L level. At this time, since the output supplied to the operational amplifier 30 side via the diode 37 becomes 0, the operational amplifier 30 compares the output voltage V ₀ and the reference voltage V ₁ , and the output becomes L level and the transistor 40 Turn on the compressor.
Therefore, if the temperature rises rapidly after the compressor is turned OFF and this temperature exceeds the compressor ON setting level M within the set time T, the compressor will be turned ON at the same time as the output from the timer circuit 4 is restored. . (See Figure 2 d) Also, as shown in characteristic B, after the compressor is turned OFF, the temperature on the surface of the evaporator or its vicinity gradually rises, and after the time set by timer circuit 4 has elapsed, this temperature reaches the ON setting level M. In this case, the compressor does not turn ON when the output of the timer circuit 4 is restored after time T has elapsed, but when the temperature on the evaporator side reaches the ON setting level M, as shown in Figure 2 e.
It becomes ON. Therefore, when the temperature on the surface of the evaporator or its vicinity is low, the compressor remains OFF even after the timer circuit 4 is restored.
Since the compressor is set to 1, power consumption of the compressor can be reduced, and acceleration and climbing can be performed smoothly.

Next, when cooler switch 1 is turned on at the beginning of compressor operation, the temperature on the surface of the evaporator or its vicinity is still at the set level P.
(which corresponds to voltage V ₂ and is a certain amount larger than level N), comparator circuit 4
An L level output is sent from the operational amplifier 44 of No. 3, which turns on the diode 47, so that acceleration or hill climbing is performed at this time, and the acceleration switch 2 turns on and a trigger pulse is sent from the trigger circuit 3. Moko's trigger pulse is resistor 28,
It is absorbed through the diode 47 and the timer circuit 4
Since the signal is not sent to the side, timer circuit 4 does not operate.
For this reason, the compressor is not turned off by the thermoswitch circuit 5 as shown in FIG. 2f. Therefore, the cabin is quickly cooled down in the early stages of cooling, and the inside air temperature can be quickly lowered.

In the present invention, the output from the operational amplifier 20 constituting the timer circuit may be directly supplied to the transistor 40 via the diode 60, as shown in FIG. In this case, the output of operational amplifier 30 is supplied to transistor 40 via diode 61. With this configuration, the transistor 40 can be always turned off when the timer circuit 4 is operating, and the compressor can be turned off. Therefore, when the output from the timer circuit 40 returns from the H level to the L level, the compressor returns to ON even if the temperature at or near the surface of the evaporator has not reached the ON setting level M.

Although the present invention has been described as using a pressure switch that detects the pressure in the intake pipe of the engine as a means for detecting the load on the engine, the present invention is not limited to this, and may also detect the pressure in the exhaust pipe of the engine. A switch, a switch that detects the operation of an accelerator pedal, a detection circuit that detects the speed of the vehicle, or the like may be used. Furthermore, it goes without saying that the present invention can be implemented using a computer or a microcomputer.

As explained above, according to the present invention, there is a thermoswitch circuit that detects the temperature on or near the surface of the evaporator and turns off the compressor when this temperature drops to a set level, and detects the load condition of the engine. In an air conditioner for a vehicle, which is equipped with an engine load detection circuit that controls the thermoswitch circuit and turns off the compressor when the engine load becomes large, A comparison circuit is provided to compare the operation setting level in the circuit with a second setting level higher than the operating setting level, and the output of this comparison circuit is used to prevent control of the thermoswitch circuit based on the operation of the engine load detection circuit. Therefore, there is no risk that the compressor will turn off even if the engine's load detection circuit operates in the early stages of compressor operation, and this allows the temperature inside the vehicle to be quickly cooled down. If the engine load increases while the nearby temperature has dropped to the set level, the compressor can be turned off for the time set in the timer circuit, allowing smooth acceleration and climbing.

[Brief explanation of the drawing]

FIG. 1 is a circuit diagram showing one embodiment of the vehicle air conditioner according to the present invention, FIG. 2 is a characteristic diagram for explaining its operation, and FIG. 3 is another example of the vehicle air conditioner according to the present invention. FIG. 2 is a circuit diagram showing an example. 1...Cooler switch, 2...Pressure switch,
3...Trigger circuit, 4...Timer circuit, 5...Thermoswitch circuit, 6...Sensor, 7...Magnetic clutch, 11, 20, 30, 44...Operation amplifier, 43...Comparison circuit.

Claims (1)

[Claims] 1. When the temperature on or near the surface of the evaporator drops to a first set level, the compressor is activated.
There is a thermoswitch circuit that turns off the engine, and when the engine load increases, the thermoswitch circuit is controlled to turn off the compressor.
The engine load detection circuit to be set to OFF, the temperature on or near the surface of the evaporator, and the first
It is equipped with a comparator that compares the set level with a second set level, and if the temperature on the surface of the evaporator or its vicinity is higher than the second set level, the engine load detection circuit controls the thermoswitch circuit. An air conditioner for a vehicle characterized by preventing 2 Connect the thermo switch circuit to the surface of the evaporator,
or a comparator circuit for compressor control that compares the temperature in the vicinity thereof with a first set level, and increases or decreases the input to the comparator circuit according to the output from the engine load detection circuit to control the thermoswitch. An air conditioner for a vehicle according to claim 1, wherein a compressor controlled by the circuit is set to off. 3. The comparator consists of a comparison circuit that compares the temperature on or near the surface of the evaporator with a second set level, and based on the output of this comparison circuit, a signal is sent from the engine load detection circuit to the thermoswitch circuit. An air conditioner for a vehicle according to claim 1, which is configured to prevent the above.