JPS62213627A - Control device for automatic ventilation fan - Google Patents

Abstract

PURPOSE:To reduce the number of component parts and decrease an electrical current in a circuit by a method wherein a concentration of reducing gas and a heat of atmosphere are detected by a gas detecting element and a thermal sensing element, and a modified wave sensed signal is outputted through a single non-stable multi-vibrator circuit in response to a change in these resistance values. CONSTITUTION:A change in resistance value of a gas sensing element 1 is converted into a change in DC current through a circuit 2, changed into ON time of a rectangular wave through a circuit 3 and then inputted into a computer 4. If a concentration of reducing gas is increased, a resistance value of an element 1 is decreased, and ON time of the rectangular wave is shortened. When this rate of change is increased to more than the desired value, the computer 4 may operate a switching element 5 so as to drive a motor 6. A change in of resistance value of a thermal sensing element 7 is changed into OFF time of rectangular wave through the circuit 3 and then inputted into the computer 4. As a temperature is increased, a resistance value of the element 7 is decreased, and OFF time of the computer 4 is shortened. As this rate of variation is increased more than the desired value, the computer 4 may operate the element 5 and drive the motor 6.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention provides a ventilation fan using a detection element whose resistance value changes in response to reducing gas and a detection element whose resistance value changes in response to heat. This invention relates to a control device for an automatic ventilation fan that automatically operates a ventilation fan.

2. Description of the Related Art Conventionally, a control circuit for this type of ventilation fan has a configuration as shown in FIG. 2, although no specific literature is cited. That is, in the figure, 1o1 is a gas detection element,
Its resistance value changes with changes in the concentration of reducing gas in the air. The change in resistance value is detected by the DC voltage conversion circuit 102.
The astable multivibrator circuit 103 converts the DC voltage change into a change in the on-time of a square wave, which is input to the microcomputer 104 as a square wave detection signal.

When the concentration of the reducing gas increases, the resistance value of the gas detection element 101 decreases, and the astable multivibrator circuit 10
3, the on time of the square wave detection signal input to the microcomputer 104 becomes shorter.

When the degree of change in this on-time increases beyond a predetermined value, an output signal is output from the microcomputer 104,
By operating the switching element 105, the ventilation fan motor 10
Drive 6.

In addition, 1oA is a heat detection element whose resistance value changes with changes in air temperature.The change in resistance value is converted into a change in off time of a square wave by an astable multivibrator circuit 10B, and a square wave is generated. The signal is input to the microcomputer 104 as a wave detection signal. As the temperature of the air increases, the resistance value of the heat detection element 107 becomes smaller, and the off time of the square wave detection signal input from the astable multivibrator circuit 108 to the microcomputer 104 becomes shorter. When the degree of change in the off time becomes greater than a predetermined value, an output signal is output from the microcomputer 104 to operate the switching element 106 and drive the motor 106 of the ventilation fan.

91 Problems to be Solved by the Invention In such a conventional configuration, the astable multivibrator circuit 103 converts the change in resistance value of the gas detection element 101 into time, and the change in resistance value of the heat detection element 107 converts the change in resistance value into time. Since there is an astable multi-pie break circuit 108, the number of parts increases, and the microcomputer 104
There was a problem in that the number of signals input to the circuit increased, and the circuit current also increased.

The present invention solves these problems by having a gas detection element and a heat detection element, reducing the number of signals input to the microcomputer, reducing the number of parts, and further reducing the circuit current. This is the purpose.

Means for Solving the Problem In order to solve this problem, the present invention provides a gas detection element whose resistance value changes in response to reducing gas, and a heat detection element whose resistance value changes in response to heat. and an astable multivibrator circuit that outputs a square wave detection signal that changes according to a change in the resistance value of each of the detection elements, and when the degree of change of this square wave detection signal becomes greater than a predetermined value. The device is composed of a microcomputer that outputs an output signal to the fan, and a switching element that operates the ventilation fan based on the output signal of the microcomputer.

Function: With this configuration, the astable multivibrator circuit that inputs the change in the resistance value of the gas detection element to the microcomputer and the astable multivibrator circuit that inputs the change in the resistance value of the heat detection element to the microcomputer are common. Therefore, only one detection signal is input to the microcomputer, the number of parts is reduced, and the circuit current is further reduced.

Example Hereinafter, one embodiment of the present invention will be described based on FIG.

In FIG. 1, the astable multi-pipe break circuit 3 is
The on time of the square wave is determined according to the resistance value of the gas detection element 1 that changes in response to reducing gas, and the off time of the square wave is determined according to the resistance value of the heat detection element 7 that changes in response to heat. It outputs a square wave detection signal that changes the current, and is connected to the microcomputer 4. 2 is a DC voltage conversion circuit, which converts a change in the resistance value of the gas detection element 1 into a change in DC voltage. 5 is a switching element connected between the output section of the microcomputer 4 and the motor 6 of the ventilation fan.

The operation of the automatic ventilation fan in the above configuration will be explained below.

The change in the resistance value of the gas detection element 1 is determined by the DC voltage conversion circuit 2.
The signal is converted into a DC voltage change by the astable multivibrator circuit 3, and is changed into a square wave on time by the astable multivibrator circuit 3, which is input to the microcomputer 4 as a square wave detection signal. As the concentration of the reducing gas increases, the resistance value of the gas detection element 1 becomes smaller, and the on-time of the square wave input from the astable multivibrator circuit 3 to the microcomputer 4 becomes shorter. When the degree of change in the on-time increases beyond a predetermined value, the microcomputer 4 outputs an output signal to operate the switching element S and drive the motor 6 of the ventilation fan.

Further, the change in the resistance value of the heat detection element 7 is changed during the off time of the square wave by the astable multivibrator circuit 3, and becomes a square wave detection signal, which is sent to the microcomputer 4.
is input. As the temperature rises, the resistance value of the heat detection element 7 becomes smaller, and the off time of the square wave input from the astable multivibrator circuit 3 to the microcomputer 4 becomes shorter. When the degree of change in the OFF time becomes greater than a predetermined value, an output signal is output from the microcomputer 4, which operates the switching element 5 to operate the ventilation fan motor 6.
drive.

As described above, according to this embodiment, changes in the resistance values of the gas detection element 1 and the heat detection element 7 can be processed by the single astable multivibrator circuit 3, and therefore the input signal to the microcomputer is In addition, the number of parts is reduced, and the circuit current is also reduced.

In the embodiment, a change in the resistance value of the gas detection element 1 is converted into a change in the on time of the square wave detection signal, and a change in the resistance value of the heat detection element is converted into a change in the off time of the square wave detection signal. However, it goes without saying that the opposite case is also possible.

Effects of the Invention As is clear from the above description of the embodiments, according to the present invention, the concentration of reducing gas and the heat of the atmosphere are detected by the gas detection element and the heat detection element, and the By outputting a square wave detection signal with a single astable multivibrator circuit, the detection signal input to the microcomputer can be unified, the number of parts can be reduced, and the circuit current can be reduced, which has practical effects. is big.

[Brief explanation of drawings]

FIG. 1 is a circuit diagram of an automatic ventilation fan control device according to an embodiment of the present invention, and FIG. 2 is a circuit diagram of a conventional automatic ventilation fan control device. 1... Gas detection element, 3... Astable multivibrator circuit, 4... Microcomputer, 6... Switching element, 6...
...Motor, 7...Heat detection element.

Claims (1)

[Claims] A gas detection element whose resistance value changes in response to reducing gas, a heat detection element whose resistance value changes in response to heat, and a square wave that changes in response to changes in the resistance value of each of the above-mentioned detection elements. A single astable multivibrator circuit that outputs a detection signal, a microcomputer that outputs an output signal when the degree of change of this square wave detection signal becomes greater than a predetermined value, and an output signal based on the output signal of this microcomputer. An automatic ventilation fan control device comprising a switching element for operating a ventilation fan.