JPS60260837A - Gas detecting device - Google Patents

Abstract

PURPOSE:To constitute a gas detecting device having low electric power consumption by detecting with two gas density levels of high and low plural gas detecting member detecting varied sorts of gases and the output signal of a gas sensor equipped with a heater for heating it. CONSTITUTION:A compound gas sensor 2 is composed of two gas detecting members 21, 22 and one sensor heater 23. Each detecting member detects a different gas respectively, for instance, the detecting member 22 is used for detecting an imperfect combustion gas (CO) and the detecting member 21 for detecting a city gas (CH4, H2, etc.). Comparators 3, 4 and 5 for detecting the resistance change of the detecting member are connected to these detecting members 21, 22. For instance the resistance value of the gas detecting member 21 is declined and the output signal of the comparator 3 becomes on H level in case of the leakage of a city gas. When the gas density becomes higher, the comparator 4 becomes on H level. In case of an imperfect combustion gas the comparator 5 becomes on H level. An alarm display device, etc. are operated by these output signals.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a gas detection device for detecting gases such as city gas and incomplete combustion gas.

[Technical background of the invention and its problems]

Conventionally, there is a gas detection device that detects gases such as city gas and incomplete combustion gas with a single gas sensor.

However, a single gas sensor cannot adequately respond to all the gases to be detected, and there is a possibility that generation of dangerous gas cannot be detected.

Taking this into consideration, there is a gas detection device that includes a plurality of gas sensors, but there is a problem in that increasing the number of gas sensors increases the installation space. Further, since gas sensors usually need to be heated by a heater, there is a problem in that as the number of gas sensors increases, a correspondingly large number of heaters are required, resulting in an increase in power consumption.

[Purpose of the invention]

The present invention has been made in consideration of the above circumstances, and it is an object of the present invention to provide a small-sized, low-power consumption gas detection device that is sufficiently effective for different types of gases.

[Summary of the invention]

To achieve this objective, the gas detection device according to the present invention includes a plurality of gas detection members that detect different types of gas,
The gas sensor unit has a heating unit that heats these gas detection members, and the output signals of these gas detection members are compared with the low concentration gas level, and if the output signal of any of the gas detection members exceeds the low concentration gas level. When the low concentration gas detection unit outputs the low concentration gas detection signal and the output signal of at least one of these gas detection members is compared with the high concentration gas level, this output signal indicates that the high concentration gas level is detected. The present invention is characterized by comprising a high concentration gas detection section that outputs a high concentration gas detection signal when the gas exceeds the high concentration gas.

[Embodiment of the Invention] A gas detection device according to an embodiment of the present invention is shown in the figure. The alternating current voltage from the alternating current power supply AC is transformed by the transformer T.

A rectifier diode D is connected to the terminal CN1 on the secondary side of the transformer T.
, a smoothing capacitor C1, a resistor R1, and a constant voltage diode ZD are connected. The alternating current voltage at the terminal CN1 is rectified and smoothed, becomes a constant direct current voltage by a constant voltage diode ZD, and is applied to a comparator, etc., which will be described later. A rectifying diode D2 and a smoothing capacitor C2 are also connected to the other terminal CN2 on the secondary side. The AC voltage at the terminal CN2 similarly becomes a DC voltage and is connected to the constant voltage circuit 1.

The composite gas sensor 2 is composed of two gas detection members 21 and 22 and one sensor heater 23. The gas detection members 21 and 22 are members that detect different gases. In this embodiment, the gas detection member 22 mainly detects incomplete combustion gas (Go), and the gas detection member 21 mainly detects city gas (Go). CH4°112, etc.) is detected. A constant voltage is applied to the sensor heater 23 from the constant voltage circuit 1 .

This is because the sensitivity of the gas detection members 21, 22 depends on the concentration, so it is necessary to heat them with a precise constant voltage. Gas detection members 21 and 22 are connected to resistors R and R8, respectively, and their connection points are connected to one terminal of comparators 3, 4.5, respectively. When the gas concentration changes and the resistance value of the gas detection member 21.22 changes, the input voltage to one terminal of the comparator 3, 4.5 changes, and the gas concentration can be detected.

Resistors R3, R4, and R5 are connected in series to divide the DC power supply voltage, and the contact points of resistors R3 and R4 are connected to the child terminal of comparator 3, and the connection point of resistors R4 and R5 is the child terminal of comparator 4. Connected to the terminal. Therefore, a low constant voltage is input to comparator 3, and comparator 4
A high constant voltage is input to. A connection point between resistors R and RIG is connected to a child terminal of the comparator 5, and a constant voltage is input thereto. Note that resistors R6 and R7 are connected between the input and output of the comparators 3 and 4, respectively.

Diode 3 is connected to the output of comparators 3 and 5, respectively.
and 4 are connected, and the cathodes of diodes 3 and 4 are commonly connected and connected to resistors R11 and R12 to form an OR circuit. The base of transistor TR1 is connected to resistor R
11 and R12. An LED 6 and a resistor R13 are connected in series to the transistor TR1. A resistor R1 is further connected to the collector of the transistor TR1.
4 and a diode D5 are connected. Diode D5
The cathode of is connected to the gate terminal of the triac 7.

The triac 7, resistor R15, and capacitor C3 are used to apply alternating current voltage to the ventilation fan motor 8 to rotate it. A control signal to the gate terminal of the triac 7 causes the triac 7 to become active, so that the drive of the ventilation fan motor 8 can be controlled. The output terminal of the comparator 4 is connected to the base of the transistor TR2. Alarm means 9 is connected in series with transistor TR2. Possible warning means include a buzzer, a display □ using an LED, or the output of an alarm signal to the outside.

Next, the operation will be explained. As mentioned above, the gas detection member 2
Reference numeral 1 detects city gas, and gas detection member 22 detects incomplete combustion gas. The reference voltage of the comparator 3 corresponds to a concentration level of city gas that is not dangerous but requires ventilation, and the reference voltage of the converter 4 corresponds to a dangerously high concentration level of city gas. It is also assumed that the reference voltage of the converter 5 corresponds to a concentration level of incompletely combusted gas that is not dangerous but should be ventilated.

For example, if city gas leaks from the gas appliance you are using,
The resistance value of the gas detection member 21 decreases according to the gas concentration.

When the resistance value decreases, the voltage level input to one terminal of the comparator 4 gradually decreases, and when it becomes lower than the voltage level to the child terminal of the comparator 3, the output signal of the comparator 3 becomes 1'' level, and the diode D3 It is forward biased and makes the transistor R1 conductive. When the transistor TR1 becomes conductive, the LED 6 lights up and the triac 7 is activated by a control signal sent to the gate terminal of the triac 7 via the resistor R1 and the diode D3. As a result, the ventilation fan motor 8 starts rotating.

When the concentration of city gas further increases and the resistance value of the gas detection member 21 decreases to become lower than the voltage level applied to the + terminal of the comparator 4, the comparator 4 outputs an H level signal. This H level signal causes transistor TR2 to
is turned on, and the alarm means 9 is turned on. This alerts you to a dangerous situation.

For incomplete combustion gas, only the comparator 5 is provided in this embodiment. When incomplete combustion gas is generated and its concentration increases, the resistance value of the gas detection member 22 decreases, and the voltage level applied to one terminal of the comparator 5 decreases.

The level to one terminal of comparator 5 becomes low, and the child terminal,
comparator 5 becomes H
Outputs level signal. As a result, the diode P4 is forward biased, and when the transistor TRI is turned on, the LED 6 lights up and the ventilation fan motor 8 rotates as described above.

According to this embodiment, when either city gas or incomplete combustion gas exceeds a certain concentration level, the ventilation fan motor rotates to exhaust the gas, and when the concentration of city gas reaches a dangerous level, an alarm is issued. can be produced. Furthermore, according to this embodiment, one heater coil of the gas sensor can be used for both purposes, so power consumption is low and circuit components (transformers, constant voltage circuits, etc.) can be downsized. Furthermore, since only one sensor space is required, it is possible to downsize the device.

These make it possible to reduce the cost of the device.

Furthermore, the functionality can be expanded depending on the type of gas to be detected and the number of times it is detected, allowing for various applications.

Note that a comparator for detecting a high 81 degree level similar to the comparator 4 may be provided for incomplete combustion gas, and its output may be used to form the third circuit with the output of the comparator 4. In this way, an alarm can be issued when the concentration of incomplete combustion gas becomes dangerous.

Furthermore, the type of gas to be detected is not limited to incomplete combustion gas and city gas, but may also be other gases such as propane gas or toxic gas.

〔Effect of the invention〕

As described above, according to the present invention, it is possible to realize a gas detection device that is sufficiently effective for different types of gases, is small in size, and has low power consumption.

[Brief explanation of drawings]

The figure is a circuit diagram of a gas detection device according to an embodiment of the present invention. 1... Constant voltage circuit, 2... Composite gas sensor, 3.4
．． 5... Comparator, 6... LED, 7... Triac, 8... Ventilation fan motor, 9... Alarm means. Applicant's agent Kiyoshi Inomata

Claims (1)

[Claims] 1. A gas sensor unit that includes a plurality of gas detection members that detect different types of gases and a heating unit that heats these gas detection members; a low concentration gas detection section that outputs a low concentration gas detection signal when the output signal of any of the gas detection members exceeds the low concentration gas level; and at least one gas detection unit among these gas detection members. A gas detection device comprising: a high concentration gas detection section that compares an output signal of a member with a high concentration gas level and outputs a high concentration gas detection signal when the output signal exceeds the high 81 degree gas level. 2. In the gas detection device according to claim vJJ, paragraph 1, the low 11i gas detection signal is a ventilation means operation signal that operates a ventilation means, and the high concentration gas detection signal is a ventilation means operation signal that operates an alarm means. Gas detection device 0 characterized in that it is an alarm means operation signal that causes