JPH0453575Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a gas sensor signal processing device.

[Prior Art] Recently, gas meters have been installed that use a gas sensor to detect a gas leak and activate an attached gas cutoff device when a gas leak is detected. Conventionally, the gas sensor outputs a voltage signal. Since a gas sensor is used, a gas sensor signal processing device that converts the signal into a predetermined signal for the gas cutoff device is connected between the gas sensor and the gas cutoff device.

[Problems to be solved by the invention] By the way, since gas meters are usually installed outdoors, it is customary to use a gas sensor signal processing device attached to the gas meter that is molded with epoxy resin to make it waterproof. However, it has been difficult to provide an externally operable test switch that operates the sensor signal processing device to generate a pseudo detection output regardless of the actual operation of the gas sensor.

This invention was devised in view of the above-mentioned problems, and its purpose is to have the same waterproof function as conventional ones, and to be able to operate the test switch for performing test operations regardless of the mold. The present invention provides a gas sensor signal processing device.

[Means for Solving the Problems] The present invention incorporates a signal processing circuit in the device body that discriminates the signal voltage from the gas sensor that generates a voltage signal depending on when a gas leak is detected or when a gas leak is not detected, and generates a detection output. In the gas sensor signal processing device, which is molded in resin and built in, a reed switch is used as a test switch that generates a pseudo detection output similar to that when detecting a gas leak, and the signal processing circuit is molded in resin and built into the body. characterized by something.

[Function] When generating a pseudo detection output from the signal processing circuit, a test switch consisting of a reed switch is turned on by a magnet from outside the resin-molded body, whereby the signal processing circuit can be operated pseudo-wise and the above-mentioned detection output can be generated regardless of the resin molding.

[Embodiment] Fig. 1 shows the circuit configuration of an embodiment of the present invention, in which a gas sensor 1 is connected to input terminals I ₁ and I ₂ of a signal processing circuit 2, and the voltage signal thereof is inputted. It's summery. This voltage signal is input through resistor _R1 and diode bridge DB, and _FETQ1 ,
A predetermined voltage is set by a constant voltage circuit consisting of a Zener diode ZD ₁ and a resistor R ₂ . This voltage is divided by resistors R ₃ and R ₄ and input to the inverter IN ₁ , and is stepped down to a constant voltage by the constant voltage IC 3 and input to the NAND gate NAND ₁ via the resistor R ₃ . Inverter IN ₁ inverts the output
The signal is input to the inverter IN ₃ through an integrating circuit consisting of IN ₂ , resistor R ₅ , capacitor C ₃ , and resistor R ₆ . The inverter IN ₃ inputs its output to the NAND gate NAND ₁ and performs a NAND with the output from the constant voltage IC ₂ . NAND gate NAN ₁ output resistor R ₇
A _series circuit of resistors R 9 and R ₁₀ is connected between the resistor ₉ and the ground line, and a light emitting diode LED of a photocoupler PH is connected to the resistor ₉ . The test switch SW, which is the main component of the present invention, is composed of a reed switch and is connected to the connection point between the resistor _R8 and the input end of the NAND gate _NAND1 . In addition, surge absorption element Z
is an element to absorb high voltage when it is superimposed on the line, capacitors C ₁ and C ₂ are noise removal capacitors, diode D is a discharge diode, resistor R ₁₁ and Zener diode ZD ₂
is an element for setting the output voltage of the photocoupler PH.

Figure 2 shows an external perspective view of the device of the present invention, in which a circuit board with the circuit shown in Figure 1 wired inside the container body 4 is molded with epoxy resin to make it waterproof, and a gas sensor 1 is connected to the outside. An input terminal lead wire 5 for the photocoupler PH and an output terminal lead wire 5 for the photocoupler PH are drawn out.

Thus, the gas sensor 1 of the signal processing circuit 2 outputs, for example, a 6V voltage signal when a non-gas leak is detected, and a 12V voltage signal when a gas leak is detected. When the wire is disconnected, it becomes a 0V signal.

Here, the Zener diode of the above voltage regulator circuit
If ZD ₁ is set to a voltage higher than 6V and lower than 12V, the voltage across resistors R ₃ and R ₄ will be 6V when no gas leak is detected, and the Zener diode ZD ₁ will set the voltage when gas leak is detected. A voltage will be applied.

Therefore, the voltage division ratio by resistors R ₃ and R ₄ and the Zener diode voltage of Zener diode ZD ₁ are determined such that the input of inverter IN ₁ becomes "L" when no gas leak is detected, and vice versa when gas leak is detected. By setting the input of inverter IN ₁ to be "H", the output of NAND gate NAND _{1 becomes "L" when no gas leak is detected, and the output of NAND gate NAND 1 becomes} "H" when gas leak is detected. Photocoupler PH light emitting diode when detecting gas leak
By lighting the LED and turning on the phototransistor PT, a detection output can be generated from the output terminals O ₁ and O ₂ .

Next, when testing whether this device operates normally, turn on the test switch SW using a magnet from outside the container 3.

In other words, the test switch is activated when no gas leak is detected.
When the SW is off, the input of the NAND gate NAND ₁ is "H", "H", and the output of the NAND gate NAND ₁ is in the "L" state, but the test switch
When the SW is turned on, the inputs of the NAND gate NAND ₁ become "H" and "L", and its output is inverted to "H", generating the same detection output as when detecting a gas leak. In other words, it is possible to create a pseudo gas leak detection operating state, and it is possible to determine whether or not it is operating normally.

[Effects] In the gas sensor signal processing device configured as described above, the present invention comprises a reed switch as a test switch that generates a pseudo detection output similar to that when detecting a gas leak, and molds the test switch with a signal processing circuit in resin. Because of this, the test switch can be freely operated from outside the device using a magnet.
Therefore, it has the advantage of being able to have a test function without sacrificing the waterproof effect.

[Brief explanation of the drawing]

FIG. 1 is a circuit configuration diagram of an embodiment of the present invention, and FIG. 2 is an external perspective view of the same. 1...Gas sensor, 2...Signal processing circuit, 4...
...It is a device body, SW...test switch.

Claims (1)

[Scope of utility model registration request] In the gas sensor signal processing device, a signal processing circuit that generates a detection output by discriminating the signal voltage from the gas sensor that generates a voltage signal corresponding to when a gas leak is detected or when a gas leak is not detected is molded into the body of the gas sensor. This gas sensor signal processing device consists of a reed switch that generates a pseudo-detection output similar to that used when detecting a leak, and is molded in resin with a signal processing circuit and built into the device.