JPS591145Y2 - ventilation system - Google Patents

Description

[Detailed description of the invention] This invention relates to a ventilation system that automatically adjusts the speed of a ventilation fan according to changes in the environment.

FIG. 1 shows a conventional ventilation system that uses a thyristor in the drive circuit and continuously varies the speed of the ventilation fan through phase control.

In this ventilation system, a smoke sensor 2 made of a semiconductor that is sensitive to smoke is provided on the secondary side of a transformer 1, and the resistance 3a of a photocoupler 3 is changed by the output of this sensor 2.

A capacitor 4 is charged through this resistor 3a, and the phase of a thyristor 6 in the main circuit is controlled via a bidirectional diode 5 based on the potential between its terminals.

This thyristor 6 is inserted in series with the induction motor 8 for driving the ventilation fan 7, so the induction motor 8 is connected to the smoke sensor 2.
A phase-controlled current is supplied according to the output of the motor, and the speed can be changed continuously.

In addition, in the figure, 9a and 9b are variable resistors for adjustment, and 10a~
10g is a resistor, and 11a and 11b are capacitors.

Since this ventilation system controls the speed of the induction motor by controlling the phase of the thyristor, electromagnetic noise due to the harmonics contained in the phase control waveform and the impact when the thyristor is fired mixes into audio equipment such as radios.

Therefore, if you use audio equipment near a ventilation system, the noise will not only make it difficult to hear, but also cause constant discomfort.

This invention improves on this, and by adopting a configuration that does not use a phase control thyristor circuit in the ventilation fan drive circuit, it is possible to accurately and automatically adjust the ventilation fan in response to changes in the environment without generating electromagnetic noise. The purpose is to provide a ventilation system that is suitable for

An embodiment of this invention will be described below with reference to the drawings.

In FIG. 2, reference numeral 21 denotes a transformer connected to an AC power source, and a detection element for detecting the state of the environment, such as a smoke sensor 22 made of a semiconductor sensitive to smoke, and a smoothing circuit 23 are connected to the secondary side of the transformer. The output end of is connected to a square wave oscillation circuit 24 such as a multivibrator.

This square wave oscillation circuit 24 generates a square wave whose pulse width changes depending on the output of the detection element.

The output end of this square wave oscillation circuit 24 is connected to the control side of a solid state relay 25, and this relay 25 is further connected in series with an induction motor 27 equipped with a ventilation fan 26 to connect it to the secondary side of the transformer 21. Connecting.

The induction motor 27 with ventilation fan is controlled by a solid state relay 25, and this solid state relay 25 inputs the pulse width of the square wave signal generated by the square wave oscillation circuit 24 to the induction motor 27 with ventilation fan. The energizing period of the alternating current is switched and controlled at the time of the zero cross of the alternating current.

Since this ventilation system has the above-mentioned configuration, when the frost surrounding the smoke sensor 22 is currently placed is filled with smoke, this sensor 22 is activated, and its output causes the square wave oscillation circuit 24 to be activated. The constant changes to change the pulse width of the output square wave signal.

If this square wave signal has a waveform as shown in FIG. 3A, and the commercial AC power supply has a waveform as shown in FIG. As shown in FIG. 2, a waveform current is supplied to the ventilation fan-equipped induction motor 27, which is switched and intermittent at the zero cross of the alternating current according to the pulse width.

The duration of this current depends on the pulse width of the square wave, which corresponds to the output of the smoke sensor 22, so the induction motor 27 with ventilation fan automatically adjusts its speed according to the output of the smoke sensor 22, that is, the amount of smoke. It is possible to maintain a comfortable living environment by changing and discharging smoke.

Moreover, since this ventilation system does not use a phase-controlled thyristor circuit in the drive circuit of the ventilation fan, it does not generate electromagnetic noise that occurs in nearby audio equipment, which has been a problem in the past.
It is also possible to provide accurate ventilation.

Note that this invention is not limited to the above-mentioned embodiments, and can be implemented with various modifications without changing the gist.

For example, in the above embodiment, a smoke sensor is used as an example of an element for detecting an environmental condition to detect smoke and ventilate. However, this invention is applicable not only to such a case but also to detect temperature, Those compatible with various environments such as humidity and gas can be used, and one or more of these can be used in combination to maintain a comfortable living environment.

As described above, according to this invention, by adopting a configuration that does not use a phase-controlled thyristor circuit in the drive circuit of the ventilation fan, it does not generate electromagnetic noise, so it does not have a negative impact on nearby audio equipment, etc. It is possible to provide a ventilation device that can accurately and automatically adjust the amount of ventilation according to the amount of ventilation.

[Brief explanation of the drawing]

Fig. 1 is a circuit diagram of an example of a conventional ventilation system, Fig. 2 is a schematic circuit diagram of an embodiment of this invention, and Fig. 3 is a waveform diagram for explaining the operation of this embodiment. be. 1...Transformer, 2...Smoke sensor, 3.
...Photocoupler, 4...Container,
5... Thyristor, 6... Thyristor, 7... Ventilation fan, 8... Induction motor,
9 a, 9 b...variable resistor, 10 a to 1
0h...Resistor, lla, llb...Capacitor, 21...Transformer, 22...
Smoke sensor, 23... Smoothing circuit, 24...
・Square wave oscillation circuit, 25... Sonorado state relay, 26... Ventilation fan, 27... Induction motor.

Claims (1)

[Scope of utility model registration request] A detection element that detects the state of the environment, a square wave oscillation circuit whose pulse width changes according to the output of this element, a solid state relay controlled by this oscillation circuit, and an induction motor with a ventilation fan controlled by this relay. and
The solid state relay is configured to control the energization period of the alternating current input to the ventilation fan-equipped induction motor by switching it at the zero cross of the alternating current according to the pulse width of the square wave signal generated by the oscillation circuit. Features ventilation equipment.