JP2991807B2 - 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 for judging an output from a sensor in two stages to prevent false alarms.

[0002]

2. Description of the Related Art Gas leak alarms for general households are liable to produce false alarms due to insecticide sprays containing flammable components. For 10 seconds, an alarm using a semiconductor type sensor may sound an alarm for several minutes.

In order to prevent such a situation, the determination level of the sensor output is divided into two levels, and the time required for the sensor output to reach the second level from the first level is measured. For example, it is determined that the insecticide or the like has been ejected, and the subsequent functions of alarm and signal output are stopped for a certain period of time.

[0004]

Although such a method is certainly effective in preventing false reports and mistransmissions caused by the insecticide spray, it is necessary to carry out periodic inspections with a check gas required by consumers. Had a problem that this function would be a problem. That is, the concentration of the combustible gas injected from the checker reaches a high concentration in the same pattern as when the insecticide is sprayed from the insecticide spray in the sensor chamber, so that the inspection using the check gas cannot be effectively performed. there were.

[0005] In addition, there is the same disadvantage in the check other than the periodic check, that is, the check immediately after installation at the consumer's house. Further, the NO-GO determination is also made at the time of the concentration check performed at the time of shipment or at the last step of the production line. The system could not be chucked successfully.

SUMMARY OF THE INVENTION An object of the present invention is to eliminate the above-mentioned inconveniences and to accurately perform a periodic inspection using an inspection gas and an operation check in a factory.

[0007]

SUMMARY OF THE INVENTION The present invention provides a sensor for sensing gas, a first level determination circuit for determining the output of the sensor, and a determination of the output of the sensor at a higher level than the first level determination circuit. A second level determination circuit; a timer for measuring a time from when the first level determination circuit determines that gas is present to when the second level determination circuit determines that gas is present; In a gas leak alarm device having an alarm control unit that stops an alarm or signal output if the time is equal to or less than a time, from the time of turning on the power until a predetermined time elapses,
A timer is provided for stopping the function of making the determination for the alarm control unit.

This gas leak alarm can be configured to issue an alarm unconditionally for a predetermined time immediately after the output of the sensor exceeds the level determined by the first level determination circuit.

[0009]

The operation of determining whether there is a gas leak or miscellaneous gas due to insecticide or the like is stopped until a predetermined time elapses after the power is turned on. If the inspection gas is injected during this time, the operation is effectively performed and inspection can be performed.

[0010]

Next, an embodiment of the present invention will be described in detail with reference to the drawings. FIG. 1 is a configuration diagram of a gas leak alarm according to the present invention. The gas leak alarm includes a sensor 10 for sensing gas, a first level determination circuit 11 and a second level determination circuit 12 for determining the output of the sensor 10 in two stages,
U13, a power supply 14, and a piezoelectric buzzer 15 are provided. The first level judgment circuit 11, the output of the sensor 10 it is determined whether or exceeds the judgment level H ₁ shown in FIG. 2, the second level determining circuit 12 determines whether or exceeds the higher H ₁ H _2.

The CPU 13 has an alarm control unit 16, an initial buzzer suppression timer 17, an alarm control timer 18, a measurement timer 19, and an alarm time setting timer 20 according to its functions.
Divided into The alarm control unit 16 has an output port 21 for externally outputting a signal.

When the power supply 14 is connected to an AC outlet and turned on, power is supplied to each unit. At this time, the timer 17 for suppressing the initial buzzer is activated, and the function of the alarm control unit 16 is stopped for the time Ta shown in FIG. The time Ta is, for example, 30 to 40 seconds in the case of the catalytic combustion type, and 3 to 5 minutes in the case of the semiconductor type. Within this Ta time, even if the sensor 10
Even if the output that exceeds the first determination level H ₁ or H _2, such as a in FIG. 3 from the signal output from the alarm and the output port 21 by the piezoelectric buzzer 15 is not.

Next, after the elapse of Ta, the alarm control timer 18
Operates only for Tb in FIG. 3, and sends a signal to the alarm control unit 16 for this time Tb. The alarm control unit 16 stops the normal judgment based on the signals from the first level judgment circuit 11 and the second level judgment circuit 12 during the time Tb. That is, during this Tb time, no false alarm due to gas leakage or miscellaneous gas is determined, and if the inspection gas is detected by the sensor 10, the output (gas concentration) of the sensor 10 becomes as shown in FIG. during that exceeds the first determination level H _1, an alarm and a signal output. Inspections performed after the installation of the gas leak alarm are performed almost within this Tb time.

[0014] After the lapse of Tb, the output of the sensor 10 exceeds the first determination level H ₁ as shown in c in FIG. 3, the measuring timer 19 is activated, the second determination from beyond the first determination level H ₁ measuring the time to reach the level H _2. The timer 19 inhibits the alarm control unit 16 from issuing an alarm and outputting a signal from the point in time when the first level is exceeded. Then, the gas concentration exceeds the first determination level, when it reaches the second determination level H ₂ within the time determined by the timer 19 continues the inhibited state until reduced back to the first determination level H ₁ below . Meanwhile, when the gas concentration exceeds the first determination level, reaching Wait at least the time determined by the timer 19 to the second determination level H _2, an alarm control unit 19,
Gas concentration continues to alarm and signal output until reduced to the first determination level H ₂ or less.

With the above configuration using the measuring timer 19 alone, the inspection using the inspection gas cannot be performed after the time Ta + Tb. However, when performing the inspection, the alarm time setting timer 20 is operated to operate the Ta + Tb. Inspection is possible even after hours. That is, this timer 20 is set to Ta
+ Tb time gas concentration after is operated by Tc time 3 at the same time exceeds the first determination level H _1, the alarm control unit 1
6 is signaled to issue only an alarm during this Tc time. Waveform c in the figure, when reaching a longer time than the time prescribed by the measuring timer 19 to the second determination level H _2, the waveform of d, the case when it reaches the second determination level H ₂ in a short time In each case, Tc determined by the timer 20
Alert only during hours.

[0016]

According to the present invention, the determination as to whether there is a gas leak or miscellaneous gas due to an insecticide or the like is stopped from the time when the power is turned on until a predetermined time elapses. Alarm and signal output, the various checks at the factory and the inspection by the user with the inspection gas can be effectively performed.

According to the second aspect, when the gas concentration exceeds the first determination level, only the alarm can be issued unconditionally for a certain period of time, so that the user does not have to turn off the power every time during the periodic inspection. Inspection with gas can be performed.

[Brief description of the drawings]

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

FIG. 2 is a graph showing a determination level of a gas concentration (sensor output).

FIG. 3 is a waveform chart showing a relationship between a sensor output and an alarm operation.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Sensor 11 1st level judgment circuit 12 2nd level judgment circuit 14 Power supply 16 Alarm control unit 17 Timer for initial buzzer suppression 18 Timer for alarm control 19 Measurement timer 20 Timer for alarm time setting

Claims (2)

(57) [Claims] A first level determining circuit for determining an output of the sensor; a second level determining circuit for determining an output of the sensor at a higher level than the first level determining circuit; A timer for measuring the time from when the first level determination circuit determines that gas is present to when the second level determination circuit determines that gas is present, and determines the measured time. A gas leak alarm having an alarm control unit for stopping the output, wherein a gas is provided with a timer for stopping the function of making a judgment on the alarm control unit until a predetermined time elapses from when the power is turned on. Leak alarm. 2. A timer for sending a signal to the alarm control unit so as to issue an alarm only for a predetermined time immediately after the output of the sensor exceeds the level determined by the first level determination circuit, The gas leak alarm according to claim 1.