JPS5827125B2 - Vehicle air conditioning control device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a vehicle air conditioning control device, and more particularly to a device that controls air volume during heating and cooling depending on the difference between a set temperature and a detected temperature.

As an air volume control device for a vehicle air conditioner with heating and cooling functions, a temperature detection element is installed inside the vehicle to detect the temperature deviation between the set temperature and the detected temperature, and the rotation speed of the blower motor is adjusted according to this surface difference. Generally, the air volume is controlled to bring the temperature close to the set temperature.

Figure 1 shows the temperature deviation vs. air volume characteristics of this type of air volume control device.As is clear from the figure, depending on whether the temperature deviation (detected temperature - set temperature) is positive or negative, cooling operation or heating operation However, there is no difference in the characteristics themselves, and if the absolute value of the temperature difference is the same, the air volume will be the same, and if the temperature difference is within a certain value, the air volume will be the minimum within this range.

By the way, in the case of this type of vehicle air conditioning control system, sufficient heating capacity can be obtained because waste heat from the engine can be used as the heat source during heating operation, but when cooling operation is performed, a part of the engine power is used. Therefore, there is not much margin in the F4 fan capacity, and as a result, in midsummer, it is difficult to maintain the temperature inside the car near the set value with the minimum air volume, and the temperature inside the car remains unstable as it deviates from the set value. The drawback is that the air volume also changes frequently.

In view of these drawbacks, the present invention aims to provide a vehicle air conditioning control device that can realize stable temperature control regardless of heating or cooling, in which air volume control is performed by stepwise switching. In addition to creating a difference between the air volume switching point when approaching the temperature deviation zero point and the air volume switching point when moving away from it, the air volume switching points during cooling operation and heating operation are made asymmetric with respect to the temperature deviation zero point, and in the case of cooling operation. The air volume is set to be switched at a temperature difference that is closer to the zero temperature deviation point than in heating operation.

Further, according to the present invention, a control device is provided which has, in addition to such a function, an automatic correction function in which the temperature deviation zero point changes according to changes in outside air temperature.

The present invention will be explained in detail below.

FIG. 2 shows the air volume control circuit portion of the vehicle air conditioning control device according to the present invention.

In the figure, 1 is a circuit that detects the temperature deviation between the inside temperature of the vehicle and the set temperature, 2 is a circuit that uses the output of the temperature deviation detection circuit 1 to send out a signal for setting the speed of the blower motor, and 3 is the circuit that uses the output of the speed setting circuit 2 to control the speed of the blower motor. This is a circuit that performs speed switching.

The temperature deviation detection circuit 1 includes a variable resistor VR for setting the temperature inside the vehicle.
1 Temperature sensor Th using a thermistor etc. installed inside the car
1. A bridge circuit is constructed between the resistors R1 to R6, and the temperature difference corresponding to the air volume switching point is compared to the comparison amplifiers OP1 to OP.
, is used for detection.

That is, each of the comparison amplifiers OP1 to OP has a voltage (2) between each of the non-inverting input terminal voltages (1) to (4), the variable resistor VR, and the temperature sensor Th.

Compare the sumi pressure ■.

When the non-inverting input terminal voltage becomes higher than , the output changes from low level to high level.

Also, the change from high level to low level is caused by each positive feedback resistor R6.
~R0, and the air volume is changed by changing these levels.

The speed setting circuit 2 includes inverters 11 to I4. AND circuit person 1~A3. It is composed of logic circuits including OR circuits OR1 and OR2, and outputs a signal that defines the speed of the blower motor according to the outputs from comparison amplifiers OP and -OP4.

The speed switching circuit 3 connects the relay RI with the output of the speed setting circuit 2.
, 1. Turn on and off RL2 and its switching contact rl,...
By switching r12, the voltage to the blower motor BM is changed to change the speed.

That is, relay RI, 1. Both RI and 2 are off, contact r
l11. When r12 is on the NC side, blower motor BM is stopped, but when relays RLl and RL2 are both turned on, voltage is supplied to blower motor BM via resistors R14 and R15, so it is driven at low speed, and relay R 'IJ
When only relay RL1 is on, voltage is supplied through resistor R14 at intermediate speed, and when only relay RL2 is on, resistor R1
A voltage is supplied by bypassing 41R15, and each is driven at high speed.

The third section shows the temperature deviation-airflow characteristics in this control circuit.
The circuit operation will be explained with reference to the figures.

In a state where the temperature inside the vehicle is much lower than the set temperature and the temperature difference -T1 requires heating operation, the voltage in the temperature deviation detection circuit 1 is ■.

and■1. ■2. ■3. ■The relationship with 4 is ■.

〉■□〉■2〉■3〉■4 and each comparison amplifier OP1
~The outputs of OP4 are all at low level.

At this time, OR circuit OR1°OR2 in speed setting circuit 2
As for the input, only the output a of the inverter 11 becomes 1'', which turns on the relay RL2 in the speed switching circuit 3, drives the blower motor BM at high speed, and performs heating operation with the maximum air volume H.

The temperature inside the car rose slightly and the temperature deviation -T2 was V,>V.

〉■2〉■3〉■4 When the output of the comparator amplifier OP1 becomes high level, only the output a-b of the AND circuit A1 becomes T', only the relays RI, , are turned on, and the blower motor BM is turned on. By being driven at medium speed, medium air volume M
heating operation is performed.

The temperature further rises and the temperature difference is -T3, which is ■1>■2>■.

〉■3〉■4, the comparison amplifier OP1. The output of OP2 becomes a high level, and only the outputs b and C of AND circuit A3 become °°1'', relays RI, 1, and RIj2 are both turned on and the blower motor BM is driven, thereby heating with the minimum air volume. Driving takes place.

On the other hand, if the temperature difference turns positive, the temperature deviation +T4
up to ■1〉■2〉■o〉■3〉■4, and relay R
Both L and RL2 are turned on and the air volume is at its minimum ■.

Cooling operation is performed, but with temperature deviation T4 ■1>
■2〉■3〉■o〉■4, the comparator amplifier OP1.
OP2. When the output of OP3 becomes high level, AND circuit A
Only output c-d of No. 2 becomes 1'', relay RL1 is turned on, and blower motor BM is driven at medium speed, thereby performing cooling operation with intermediate air volume M.

Furthermore, the temperature difference increased to 10T5 and ■1〉■2〉■
When 3〉■4〉■o is reached, the outputs of comparator amplifiers OP1 to OP4 all become high level, and only the input d of inverter *+14 becomes °1'', relay RL2 is turned on and blower motor BM operates at high speed. The cooling operation is performed at the maximum air volume H.

For reference, a logical value table for each input/output section of the speed setting circuit 2 is shown in Table 1.

By the way, as mentioned above, in the present invention, the comparator amplifier OP1
~Resistor R for positive feedback of the output to each of OP4
Connect 6 to R9 to give the output hysteresis characteristics,
In each comparison amplifier, the air volume switching point when the temperature deviation approaches zero point, in other words, the temperature difference when decreasing the air volume, and the air volume switching point when moving away from the temperature deviation zero point, in other words, the temperature difference when increasing the air volume. I try to make a difference between them.

For example, during cooling operation, from the maximum air volume H to the intermediate air volume M
Switching to the air flow rate is performed at a temperature difference T5', while the reverse switching is performed at a temperature difference T5, which prevents the air volume from fluctuating frequently due to slight temperature fluctuations near the air volume switching point. can.

In addition, the switching point of the same air volume during cooling operation and heating operation is made asymmetrical with respect to the zero temperature difference point, and in particular, the air volume switching point to the minimum air volume during cooling operation is set to virtually the zero temperature difference point, so that the temperature By not switching to the minimum air volume until the surface difference becomes approximately 0, the interior temperature of the vehicle can be brought closer to the set value more quickly during cooling operation, allowing stable temperature control of the interior of the vehicle.

As is clear from the above, in this embodiment, the temperature deviation-air volume characteristics during heating operation and cooling operation are asymmetrical so that air volume switching is performed with a relatively smaller temperature difference during cooling operation. Avoid reducing the air volume during cooling operation to the minimum value until the temperature inside the car almost matches the set value, and make sure that there is a difference between the air volume switching point when the temperature approaches the set value and the air volume switching point when the temperature is far away. This prevents the air volume from fluctuating frequently when the temperature inside the vehicle deviates from the set value, and allows comfortable cooling with a stable air volume.

FIG. 4 shows another embodiment of the present invention regarding the temperature deviation detection circuit.

The other circuits are the same as those in FIG. 2, so illustration and explanation will be omitted.

In this embodiment, since the heating or cooling capacity is affected by the temperature outside the vehicle, the temperature deviation zero point shown in FIG. As a means for achieving this, an outside temperature sensor Th2 is inserted and connected in series with the inside temperature sensor Tb1.

This temperature deviation detection circuit 1 generates a voltage ■ when the temperature outside the vehicle becomes low.

increases for the same interior temperature, so the temperature deviation zero point for the airflow characteristics in Figure 3 moves toward the mouth by the amount of decrease in exterior temperature, and conversely, as the exterior temperature increases, the voltage
.

decreases, and the temperature deviation zero point moves in the direction of A by the amount of the temperature rise outside the vehicle.

This means that when the temperature outside the vehicle decreases, the heating load increases and the heating capacity suffers, but due to the above-mentioned effect, the heating operation is controlled with a larger air volume even for the same negative temperature deviation. On the other hand, when the temperature outside the vehicle increases and the cooling load increases, the cooling operation is controlled with a larger air volume.

As a result, the heating or cooling capacity is not affected by temperature fluctuations outside the vehicle, and stable heating or cooling can always be performed with an appropriate air volume.

As explained above, according to the present invention, the cooling capacity, which was lacking in conventional vehicle air conditioning control devices, is controlled by a larger air volume than in the past, so that the temperature can be adjusted more quickly to the set value. It is possible to perform stable cooling operation when the temperature is close to the zero point, and by controlling the temperature by changing the air volume in stages, the difference between the air volume switching point when the temperature approaches zero point and the air volume switching point when the temperature is far away can be reduced. This allows for stable heating or cooling operation in which the air volume does not fluctuate frequently due to slight temperature fluctuations.

Of course, it is clear that the air volume control circuit according to the present invention is not limited to the circuit configurations shown in FIGS. 2 and 4. For example, the number of air volume switching points can be increased by adding a comparator amplifier.

[Brief explanation of the drawing]

Figure 1 shows the temperature deviation in a conventional vehicle air conditioning control system.
FIG. 2 is a diagram showing an example of the air volume control circuit in the vehicle air conditioning control device according to the present invention, FIG. 3 is a temperature deviation-air volume characteristic diagram, and FIG. 4 is a diagram showing another implementation of the air volume control circuit. Diagram showing an example. In the figure, 1 is a temperature deviation detection circuit, 2 is a speed setting circuit, 3 is a speed switching circuit, Tb is a vehicle interior temperature sensor, OP1 to OP
4 is a comparison amplifier; 1. ~I4 is an inverter, A1-A3
is an AND circuit, OR1 and OR2 are OR circuits, RLl, R
L2 is relu, BM is blower motor, and Th2 is outside temperature sensor.

Claims (1)

[Scope of Claims] 1. In a vehicle air conditioning control device that controls heating and cooling air volume according to the difference between a set temperature and a detected temperature, a circuit that detects a temperature deviation corresponding to an air volume switching point, and the detection circuit The detection circuit includes a circuit that outputs a blower motor speed setting signal according to the output of the speed setting circuit, and a circuit that switches the speed of the blower motor based on the output of the speed setting circuit, and the detection circuit is configured to switch the air volume when the temperature difference approaches zero point. There is a difference between the air volume switching points when moving away from the point and when moving away from the air, and the air volume switching points during cooling operation and heating operation are made asymmetrical with respect to the zero temperature difference point with respect to the detected temperature deviation. Air conditioning control equipment for vehicles. 2. The vehicle air conditioning control device according to claim 1, wherein the speed switching circuit for the blower motor is constituted by a resistance switching circuit using a relay. 3. An air conditioning control device for a vehicle according to claim 1, characterized in that the air volume switching point to the minimum air volume during cooling operation is set so as to be substantially at a temperature surface difference zero point. . 4. In a vehicle air conditioning control device that controls heating and cooling air volume according to the deviation between the set temperature and the detected temperature, there is a circuit that detects the temperature difference corresponding to the air volume switching point, and a blower motor a circuit that outputs a speed setting signal, and a circuit that switches the speed of the blower motor based on the output of the speed setting circuit, and when the detection circuit is far from the air volume switching point when the temperature deviation approaches zero point, In addition to the inside temperature sensing element, an outside temperature sensing element is also installed to automatically correct the zero temperature deviation point by the change in outside air temperature. A vehicle air conditioning control device characterized by: