JPS5916184B2 - Air conditioner control device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a control device for an air conditioner, and an object thereof is to provide a control device that stably operates an air conditioner.

In conventional air conditioners, the guard for the room temperature sensor obstructs airflow, leaving the sensor part exposed, and if a hand comes close to touching the sensor part, noise is likely to enter the temperature detection signal. Also, since a compressor with a large electric capacity is used, there is a large voltage drop at the start of operation, which can easily cause noise to enter the temperature detection signal.Furthermore, the signal line from the temperature sensor may be connected to other electrical signals. Because it was bundled with the cable and not reshielded, it was easy for noise to enter.

The present invention relates to a control device that can eliminate the above-mentioned drawbacks and can operate stably even if the differential for turning the air conditioner on and off based on the temperature detection signal of the temperature sensor is small.

An embodiment of the present invention will be described based on the drawings.

In Fig. 1, 1 is a temperature detection circuit, 2 is an integration circuit, and 3 is a temperature detection circuit.
is a switching circuit, 4 is an excitation winding, and temperature detection circuit 1
The integrating circuit 2 is composed of an operational amplifier 9 and a capacitor 10 as a feedback impedance, and the switching circuit 3 is composed of resistors 11 and 12 that determine a reference potential. , an operational amplifier 13, a transistor 14, a feedback resistor 15 for applying positive feedback from the output terminal of the operational amplifier 13 to the non-inverting input terminal, and resistors 16 and 17 for applying bias to the base of the transistor 14.

A resistor 18 applies feedback from the output terminal of the operational amplifier 13 of the switching circuit 3 to the inverting input terminal of the operational amplifier 9 of the integrating circuit 2, and changes the integrated reference voltage of the integrating circuit 2 with respect to the output signal of the temperature detecting circuit 1.

It is assumed that the hysteresis width of the switching operation determined by the resistor 15 of the switching circuit 3 is larger than the ripple generated in the integrating circuit 2 when large noise enters the integrating circuit 2.

The operation of the air conditioner control device according to the present invention having the above configuration will be described next.

When the air conditioner performs a cooling function, the ambient temperature of the temperature sensor 8 of the temperature detection circuit 1 rises, and the temperature sensor 8
When the resistance value of decreases and the relationship between the potential VA at the output terminal A and the potential VB at the output terminal B of the bridge circuit constituting the temperature detection circuit 1 becomes VA<VB, the temperature detection circuit 1 The integrating circuit 2 integrates the output signal of , and the potential Vc at the output terminal C of the operational amplifier 9 of the integrating circuit 2
V(,<
VD, an output signal is output from the operational amplifier 13, the transistor 14 becomes conductive, the excitation winding 4 is excited, and the air conditioner starts operating.

Since the feedback resistor 15 of the switching circuit 3 applies positive feedback from the output terminal of the operational amplifier 13 to the non-inverting input terminal, the switching operation of the switching circuit 3 is made more reliable.

The ambient temperature of the temperature sensor 8 decreases due to the operation of the air conditioner, and the hysteresis width is determined by the resistor 18 connected to the output terminal of the operational amplifier 13 of the switching circuit 3 and the inverting input terminal of the operational amplifier 9 of the integrating circuit 2. When the temperature becomes lower than the operating start temperature of the air conditioner, the potentials of the output terminals A and B of the temperature detection circuit 1 become VA>VB,
Integrating circuit 2 performs integration in the opposite direction, and the air conditioner stops operating.

Next, there are other embodiments of the present invention shown in FIGS. 2 and 3, which have the same function as the embodiment shown in FIG. 1, but the difference is that in the case of FIG. A simple integrating circuit consisting of a resistor 19 and an electrolytic capacitor 20 is connected to the output side of an integrating circuit consisting of a resistor 19 and a bipolar capacitor 10. This allows a large input signal to be generated when operating the air conditioner's operation switch or volume resistor. enters the integrating circuit 2. If the integration time constant of the integrating circuit consisting of the operational amplifier 9 and the capacitor 10 becomes small, an 0N-OFF type output signal may be generated to the switching circuit 3, which may cause malfunction. Such malfunction can be prevented by an integrating circuit including a resistor 19 having a large constant and a capacitor 10.

In the case of FIG. 3, the comparison voltage of the switching circuit 3 is taken from the output terminal B voltage of the temperature detection circuit 1, thereby reducing the number of resistors used.

In the air conditioner control device according to the present invention, after the integration circuit 2 integrates the output signal from the temperature detection circuit 1, the switching circuit 3 is activated to operate the air conditioner. The output signal of is fed back to the integrating circuit 2 to change the integration reference voltage of the integrating circuit 2,
Turning on the air conditioner based on the temperature detection signal of the temperature sensor 8;
In cases where a differential is set to OFF and the temperature sensor 8 is exposed and installed together with the output signal line from the temperature detection circuit 1, or when the signal line from the temperature sensor 8 is connected together with other electrical signal lines. If the cable is not shielded, the noise generated from the temperature sensor 8 or the temperature detection circuit 1 will enter the integrating circuit 2.
Since this noise component is an alternating current component, by setting the integration time constant of the integrating circuit 2 to be larger than the period of the frequency component of the noise that affects the circuit operation, the switching circuit 3
does not appear in

Therefore, only the output signal from temperature detection circuit 1 is sent to integration circuit 2.
is integrated and appears in the output of the integrating circuit 2, and this output operates the switching circuit 3 to obtain a clean switching output, which reduces the differential between turning on and off the air conditioner based on the temperature detection signal of the temperature sensor 8. However, stable operation is possible without malfunctions caused by noise, and the time constant of the integrating circuit 2 can be extremely small enough to absorb noise, making it possible to precisely control the room temperature with little overshoot.

In addition, even if the output signal from the temperature detection circuit 1 is extremely small, it becomes a large output over time due to the integration operation of the integration circuit 2, so the switching circuit 3 does not require particular precision and can be a rough switching circuit 3. Become.

In addition, even if particularly large noise enters the integration circuit 2 from the temperature detection circuit 1 and a relatively large ripple occurs in the output of the integration circuit 2, the hysteresis width of the switching circuit 3 is made larger than this ripple. Circuit 3 does not malfunction.

[Brief explanation of the drawing]

1 to 3 are electrical control circuit diagrams showing different embodiments of the present invention. 1... Temperature detection circuit, 2... Integrating circuit, 3... Switching circuit, 8... Temperature sensor, 9, 13... Operational amplifier .

Claims (1)

[Claims] 1. A temperature detection circuit with a bridge circuit configuration having a temperature sensor on one side whose resistance value changes depending on the temperature, and 2.
an integrating circuit consisting of an operational amplifier having two output terminals connected to an inverting input terminal and a non-inverting input terminal; and a capacitor connected between the output terminal of the operational amplifier and the inverting input terminal; an air conditioner comprising: a switching circuit that performs switching operation according to an output signal of the air conditioner to control operation and stop of the air conditioner; and a feedback resistor connected between the output terminal of the circuit and the inverting input terminal of the operational amplifier. Control device for harmonizer. 2. The control device for an air conditioner according to claim 1, wherein the hysteresis width of the switching operation of the switching circuit is made larger than the ripple generated in the output signal from the integrating circuit.