JP3105341B2 - Gas leak alarm - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a gas leak alarm capable of suppressing generation of an alarm when a combustible insecticide spray gas is detected.

[0002]

2. Description of the Related Art FIG. 6 shows an outline of a conventional gas leak alarm of this type, in which a gas detecting section 1 including a gas detecting element for detecting a combustible gas and an output from the gas detecting section 1 are used. It comprises a discrimination alarm suppression unit 2 for discriminating whether the gas is a gas leak or a combustible insecticide spray gas, and an alarm generation unit 3 for generating an alarm in accordance with the discrimination by the discrimination alarm suppression unit 2.

[0003] The principle of discrimination by the discrimination alarm suppression unit 2 will be described with reference to FIG. FIG. 3 is an output (or alarm concentration) characteristic diagram of the gas detection element. Gas detection a shows a steep rise characteristic due to the combustible insecticide spray gas, and b shows a slow characteristic due to normal gas leakage. The discrimination alarm suppression unit 2 compares the gradient ΔD / Δt of the transition of the output of the gas detection element with a reference value, and determines whether it is a normal gas leak or a combustible insecticide spray gas according to the magnitude of the difference. When it is determined that there is a gas leak, the alarm generator 3 is operated immediately to generate an alarm, and when it is determined that the gas is a combustible insecticide spray gas, the alarm is generated by the alarm generator 3 for a fixed time or intermittently. Deter.

[0004]

However, conventionally, it has been determined whether the gas is a combustible insecticide spray gas or a gas leak based only on the magnitude of the gradient of the output characteristic or the alarm concentration characteristic of the gas detection element. If a gas leak alarm is installed near the location where the gas leaks suddenly due to detachment or breakage of the gas pipe (rubber pipe), similar to the case of the combustible insecticide spray gas, There has been a problem that the generation of the alarm is suppressed and the generation of the alarm is delayed.

An object of the present invention is to improve the accuracy of gas discrimination so as to eliminate a delay in generating an alarm in the case of sudden gas ejection.

[0006]

SUMMARY OF THE INVENTION The present invention focuses on the fact that a mist-like solvent ejected together with a combustible insecticide spray gas scatters light, detects a change in the amount of light due to the scattering, and also determines this as a discrimination factor. By doing so, the accuracy of gas discrimination is improved. That is, in the gas leak alarm device according to the present invention, in addition to the gas detection unit, the discrimination alarm suppression unit, and the alarm generation unit, a light emitting unit that detects a mist-like solvent ejected with the combustible insecticide spray gas by scattering light. And a light receiving unit. Then, the discrimination alarm suppression unit detects when the gas detection unit detects the gas and the output of the light receiving unit changes within a predetermined time, or when the output of the light receiving unit changes and the gas detection unit detects the gas within the predetermined time. At this time, the configuration is such that the combustible insecticide spray gas is determined and the alarm by the alarm generation unit is suppressed for a fixed time or intermittently.

[0007] Further, a cleaning display unit may be provided, wherein the determination alarm suppression unit determines that the output level reduction state of the light receiving unit has continued for a predetermined time or more, and operates the cleaning display unit. it can.

[0008]

In the case of the combustible insecticide spray gas, the light from the light emitting portion is scattered by the solvent and the amount of light received by the light receiving portion decreases, and the output level of the light receiving portion changes. Therefore,
If the change and the gas detection by the gas detector are obtained within a predetermined time, it is determined that the combustible insecticide spray gas is used, and in the case of sudden gas ejection due to disconnection or breakage of the gas pipe, light scattering will occur. Therefore, it is possible to accurately discriminate between the case of the combustible insecticide spray gas and the case of the sudden gas ejection.

Further, it is possible to detect that the light emitting section or the light receiving section is dirty and to indicate by the cleaning display section that cleaning is necessary.

[0010]

Next, an embodiment of the present invention will be described in detail with reference to the drawings. FIG. 1 shows a configuration example of a gas leak alarm according to the present invention. The gas leak alarm includes a light emitting unit 14, a light receiving unit 15, and a light receiving unit 15 in addition to a gas detecting unit 10, an amplification comparing unit 11, a discriminating alarm suppressing unit 12, and an alarm generating unit 13 for the gas detecting unit 10. 15 is provided with an amplification comparison unit 16 and a cleaning display unit 17.

The gas detecting section 10 has a bridge connection of a gas detecting element D for detecting a combustible gas, a temperature compensating element C, and resistors R ₁ and R ₂ , and determines an alarm level by a semi-fixed resistor VR. E is a power supply. Emitting portion 14 is constituted by the light emitting element LED ₁ and the resistor R ₃ which emits light at all times during the energization of the gas leak alarm, also the light receiving unit 15 includes a phototransistor PT for receiving light from the light emitting element LED ₁ Resistance R
Is composed of _4, the cleaning display unit 17 is constituted by a resistor R ₅ and the light-emitting element LED _2.

The output from the gas detector 10 is supplied to the amplification comparator 1
At 1, the output from the light receiving unit 15 is input to the discrimination alarm suppression unit 12 at a predetermined level or more by the amplification comparison unit 16. The discrimination / warning suppression unit 12 discriminates the input as described later, and outputs a signal for operating a buzzer or the like to the warning generation unit 13 and a signal for turning on the light emitting element LED ₂ to the cleaning display unit 17. It has become.

Next, the operation of the gas leak alarm will be described with reference to FIG.
5 will be described according to the timing chart of FIG. FIG.
Shows the operation in the case of the combustible insecticide spray gas. The output of the gas detection unit 10 is amplified by the amplification comparison unit 11 and compared with the reference level H _{1. When} the output exceeds this level H ₁ ,
The output of the amplifier / comparator 11 changes from L to H. at the same time,
A first timer whose time is set in advance in the discrimination alarm suppression unit 12 starts, and within the set time ΔT ₁ , the output from the light receiving unit 15 becomes equal to or lower than the reference level H ₂ in the amplification comparison unit 16 and the amplification is performed. When the output of the comparison unit 16 changes from H to L, that is, the combustible insecticide spray gas passes between the light-emitting unit 14 and the light-receiving unit 15 and the solvent scatters light.
When the light receiving amount of No. 5 decreases, the discrimination alarm suppression unit 12 suppresses the generation of the alarm by the alarm generation unit 13 for ΔT ₂ time preset in the second timer. If the output of the amplification comparing section 16 does not change from L to H within the set time ΔT ₃ set by the third timer after the elapse of ΔT ₁ , the light emitting section 14
It is determined that the LED ₁ and the phototransistor PT of the light receiving section 15 are dirty, and the light emitting element LED of the cleaning display section 17 is determined.
Lights up ₂ to indicate that cleaning is required. However, when the output of the amplification comparing section 16 changes from L to H within the time ΔT ₃ , the light emitting element LED ₂ does not turn on.

FIG. 3 also shows the operation in the case of the combustible insecticide spray gas, when the output from the light receiving unit 15 changes faster than the output from the gas detecting unit 10 in FIG.
In this case, the output of the amplification comparator 16 sets the time ΔT _1.
Start the first timer.

FIG. 4 shows the operation during a normal gas leak.
The output of the gas detector 10 outputs a reference level H ₁ amplifier comparator 11 beyond from changes to H from L, output the reference level from the light receiving portion 15 to the first timer is started ΔT ₁ hour If the output of the amplification comparison unit 16 remains H without falling below H _2, the output of the discrimination alarm suppression unit 12 changes from L to H after ΔT ₁ time has elapsed, and an alarm is generated by the alarm generation unit 13. .

FIG. 5 shows the operation in the case of a normal cleaning display. When the output of the amplification comparator 16 changes from H to L, ΔT ₁ +
If it does not return to H after the elapse of ΔT ₃ hours, the discrimination alarm suppression unit 12 outputs the light emitting element LED ₁ and the phototransistor P
T is determined to be dirty, and the light emitting element L of the cleaning display section 17 is determined.
Turn on ED ₂ .

[0017]

According to the present invention, the detection of the scattering of light by the solvent of the combustible insecticide spray gas passing between the light emitting section and the light receiving section and the detection of the combustible gas by the gas detection section can be performed. Since it is determined whether the gas is a normal gas leak or a combustible insecticide spray gas, it is possible to improve the accuracy of gas determination and eliminate the delay of alarm generation in the case of sudden gas ejection.

[Brief description of the drawings]

FIG. 1 is a block diagram of an example of a gas leak alarm according to the present invention.

FIG. 2 is a timing chart showing an operation when the gas leak alarm detects a combustible insecticide spray gas.

FIG. 3 is a timing chart showing an operation slightly different from FIG. 2 when a combustible insecticide spray gas is detected.

FIG. 4 is a timing chart showing an operation at the time of normal gas leak detection.

FIG. 5 is a timing chart showing an operation in a case of a normal cleaning display.

FIG. 6 is a block diagram showing a basic configuration of a conventional gas leak alarm.

FIG. 7 is a characteristic curve diagram illustrating a principle of discrimination by a discrimination alarm suppression unit of the gas leak alarm.

[Explanation of symbols]

 Reference Signs List 10 Gas detection unit 11 Amplification comparison unit 12 Discrimination alarm suppression unit 13 Alarm generation unit 14 Light emission unit 15 Light reception unit 16 Amplification comparison unit 17 Cleaning display unit

Claims (2)

(57) [Claims] 1. A gas detecting section including a gas detecting element for detecting a combustible gas, and a discriminating means for discriminating a gas leak or a combustible insecticide spray gas based on an output from the gas detecting section. In a gas leak alarm having an alarm suppressing unit and an alarm generating unit that generates an alarm according to the judgment by the discriminating alarm suppressing unit, a mist-like solvent ejected together with the combustible insecticide spray gas is detected by light scattering. A light emitting unit and a light receiving unit, wherein the discrimination alarm suppressing unit is configured to perform a predetermined time when the output of the light receiving unit changes within a predetermined time after the gas detection unit detects the gas, or when the output of the light receiving unit changes. When the gas detection unit detects the gas inside, it is determined to be a combustible insecticide spray gas, and the alarm by the alarm generation unit is configured to be suppressed for a fixed time or intermittently,
Gas leak alarm. 2. The apparatus according to claim 1, further comprising: a cleaning display unit, wherein the discrimination alarm suppression unit is configured to operate the cleaning display unit when the output level of the light receiving unit has been reduced for a predetermined time or more. A gas leak alarm according to item 1.