JPS61170896A - Gas leak alarm - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field] The present invention relates to a gas leak alarm that can change the alarm delay time depending on the gas concentration.

[Background technology]

Conventional gas leak alarms are configured to issue a gas leak alarm only when the level of the gas detection signal, which has a level proportional to the gas concentration, exceeds a certain threshold for a predetermined period of time. Even if the level of the Ganu detection signal momentarily exceeds the threshold due to gas inflow, noise, etc., the system is configured so that no gas leak alarm is issued at this time.

However, with such a configuration, it takes time to issue an alarm after detecting a gas concentration exceeding a predetermined value, which is extremely inconvenient when performing an operation test, for example.

[Object of the invention]

SUMMARY OF THE INVENTION An object of the present invention is to provide a gas leak alarm that can prevent malfunctions due to noise or instantaneous inflow of gas, and can perform operational tests in a short time.

[Disclosure of the invention]

The gas leak alarm of the present invention includes a gas detection circuit that outputs a gas detection signal at a level corresponding to the gas concentration, a first threshold set to a low level, and a second threshold set to a high level. a reference pulse generation circuit that outputs the basic pulse signal; a first comparator that compares the gas detection signal with the reference pulse signal and generates an output when the gas detection signal is larger; an integrating circuit that integrates the output of the first comparator; and a second comparison circuit that compares the output of this integrating circuit with a reference value and generates a gas leak V alarm output when the output of the integrating circuit is greater than the reference m value. It is characterized by having a configuration including a container.

In this way, the signal to be compared with the gas detection signal is set as a reference pulse signal with the first threshold set to a low level and the second threshold set to a high level, and the comparison outputs of both are integrated. Furthermore, since the integral output is compared with the reference position,
When high-level gas flows in instantaneously or when noise is added, false gas leak alarms are not issued due to the delay time caused by the integration time, and in addition, extremely high concentration gas flows in, as was the case during operation tests. In this case, the delay time due to integration is reduced, and operation tests can be performed in a short time.

A further embodiment of the present invention will be described with reference to FIGS. 1 to 3. This gas leak alarm, as shown in Figure 1,
The gas concentration is detected by the gas detection circuit 1, and the gas detection signal v8 (
(8) in FIG. 2), and on the other hand, the reference pulse generating circuit 2 generates a periodic reference voltage V pulse which sets the first threshold value vTH□ to a low level and sets the threshold value fIIvTH2 of 1g2 to a high level. By generating a signal V (Fig. 2) and comparing the gas detection signal vs and the reference pulse signal vRP with a comparator 3, it becomes high level when vs>VRp and becomes high level when v8<vRP. The comparison output signal V becomes low and becomes μ. Obtained P (Figure 2 (6), Prisoner in Figure 3). And this comparison output signal V. P is resistor 4 and capacitor 5
The integrated output signal V ((8) in FIG. 3) is integrated by an integrating circuit S/ consisting of the following: , (Fig. 3 (g)), it is found that V engineering N > vR1! : The comparison output signal becomes high level when vIN<vRF, and becomes low level when vIN<vRF, that is, gas leak alarm signal V. UT (Figure 3 (C
)t-obtained, this gas leak alarm signal V. U, the υ alarm circuit 9 is activated to notify of gas leakage.

With this configuration, when high-concentration gas momentarily flows in and the gas detection signal vs exceeds the first threshold value vTH, as in the section B in FIGS. 2 and 3, the comparison Only two pulses are output from the device 3, and even if they are integrated by the integrating circuit 6, the integrated output signal V does not exceed the reference voltage V□. To explain in more detail, the capacitor 5 is charged during the period when the comparator 3 outputs a pulse, and when the pulse is no longer output, the capacitor 5 is discharged. That is, during the period when pulses are being output periodically, the level of the integral output signal V increases as a whole while repeating rise and fall, but when no pulses are output at all, the level of the integral output signal V increases. .about. gradually decreases, and with only two pulses, the integrated output signal V does not rise to N which exceeds the reference voltage "RFi".

Therefore, the gas leak alarm signal V. The UT remains at a low level and no report is issued. Therefore, a gas leak alarm will not be erroneously issued when high concentration gas momentarily flows in or when noise occurs.

In addition, as in section B in Figures 2 and 3, there is a gas leak on the east side, and high concentration gas continues to flow in, causing the gas detection signal VESE to exceed the first threshold value vTH□. When this continues for a long time, the comparator 3 also outputs a large number of pulses, and when these are integrated by the integrating circuit 6, the level of the integrated output signal V rises and falls as a whole due to the charging and discharging operations described above. For example, when pulses 4a or more from the comparator 3 are continuously generated, the reference voltage vRE is exceeded, and at this point the gas leakage signal V is output from the comparator 7 after the line '. U, becomes high level and a gas leak alarm is issued. When the gas concentration decreases and the gas detection signal v8 falls below the threshold value vTH, the comparator 3 no longer outputs pulses, and the integrator circuit 6
The level of the fine output signal V, gradually decreases, and V,
〈When it becomes V, gas leak alarm signal V. UT becomes low level and the gas leak alarm stops.

In addition, if extremely high concentration gas flows in during the operation test, as in section C in Figures 2 and 3, the gas detection signal v8 will exceed the second threshold value vTH2, and the comparison However, if the integrating circuit 6 integrates this signal, only the charging operation will occur, and the level of the integrated output signal V will be in the B section. The reference voltage vR1 rises faster than the reference voltage vR1! , and in this case, the gas leak alarm signal V is generated within a short time after the gas inflows. U, will be output.

The gas concentration decreases and the gas detection signal v8 reaches the threshold value vTH
When it falls below 1, no pulse is output from the comparator 3, and the level of the integral output signal vIN of the integrating circuit 6 gradually decreases, and when it reaches V, the gas leak alarm signal V is output.
. UT becomes low level and the gas leak alarm stops.

As a result, when a very high concentration of gas flows in, the gas leak alarm signal V is generated even if the gas flow continues for a short period of time.

0. is output, allowing operation tests to be performed in a short time.

〔Effect of the invention〕

In the gas leak alarm of the present invention, the signal to be compared with the gas detection signal is a reference Barne signal in which the first threshold is set to a low level and the second threshold is set to a high level, and the comparison output between the two is Since the integrated output is compared with the fundamental value, when a high level of gas momentarily flows in or noise is added, a false gas leak alarm may be issued due to the delay time caused by the integration time. It doesn't melt. Furthermore, when a very high concentration of gas is flowed in, such as during an operation test, the delay time due to integration becomes shorter, allowing the operation test to be carried out in a shorter time.

[Brief explanation of drawings]

FIG. 1 is a circuit diagram of one embodiment of the present invention, and FIGS. 2 and 3 are waveform diagrams of various parts of FIG. 1. 1... Gas detection circuit, 2... Reference pulse generation circuit,
3... Comparator (first), 6... Integrating circuit, 7...
Comparator (2nd) 1+“-1’7 Fig. 1

Claims (1)

[Claims] A detection circuit outputs a gas detection signal at a level corresponding to the gas concentration, a first threshold is set to a low level, and a second threshold is set to a low level.
a reference pulse generation circuit that outputs a reference pulse signal with a high level threshold; and a first circuit that compares the gas detection signal and the reference pulse signal and generates an output when the gas detection signal is larger. a comparator, an integrating circuit that integrates the output of the first comparator, and compares the output of the integrating circuit with a reference value, and generates a gas leak alarm output when the output of the integrating circuit is greater than the reference value. A gas leak alarm comprising a second comparator.