JPH1166465A - Gas leak alarm - Google Patents

Abstract

PROBLEM TO BE SOLVED: To continuously operate a gas leak alarm over a period exceeding the service life of gas sensor elements by selectively connecting plural gas sensor parts to a gas detection part and connecting another gas sensor part while successively and selectively switching it when the connection time of the selected gas sensor part reaches the set time. SOLUTION: The time accumulation of a time measuring mechanism 22a is stared from the forwarding time point of the gas leak alarm, and its use is started while attaching the alarm at the home of a user. First of all, a 1st gas sensor part 10A is selected and its output is inputted to a sensor output discriminating circuit, corrected by the output of a temperature compensating circuit 11 and compared with a reference voltage. When the corrected output exceeds the reference voltage, gas leak is discriminated, gas leak detection is outputted to a control circuit, a red LED 24a of an alarm part 24 is continuously turned on, and sound alarm is issued from an alarm speaker 25. When the gas leak is not detected by a detection circuit 12 any more, the sound alarm is stopped. In this case, the red LED 24a is turned off under the control of a display judging part 22b after the stop of the sound alarm.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a gas detector which is installed in a room where a gas appliance is used in a general household, detects a gas leak based on an input from a gas sensor, and detects a gas leak based on a detection result of the gas detector. The present invention relates to a gas leak alarm device including an alarm unit that issues an alarm, and a purge processing unit that heats the gas sensor unit to a temperature equal to or higher than a use temperature and performs a purge process to remove adsorbed miscellaneous gas and attached dust.

[0002]

2. Description of the Related Art In the above-mentioned gas leak alarm, only one set of gas detector is provided. In general, the life of a gas sensor element is about 5 years when it is used constantly.

[0003]

In the above conventional configuration, even if the gas sensor element has deteriorated and has reached the end of its life, the operation indicator lamp is lit. However, there is a possibility that a gas leak is not detected or a false report is issued. That is, as described above, the life of the gas sensor element is about 5 years, and from the viewpoint of safety, there is a problem that each gas leak alarm has to be individually replaced each time the life is reached.

The life of the gas sensor element is determined for the following two reasons. That is, one of the cases is a case where the gas sensor element is configured by a semiconductor gas sensor such as a tin oxide semiconductor gas sensor, and the gas sensitivity increases with time, so that a false alarm is issued to respond to miscellaneous gases. The life is defined as the lifetime when the gas sensor element is composed of a contact-combustion gas sensor. Is what you do. Both of these lifespans are about 5
Years, and it is desirable to extend the life.

Accordingly, an object of the present invention is to provide a gas leak alarm which can be operated continuously over a period exceeding the life of a gas sensor element to be used, while avoiding a complicated structure and an increase in unit price.

[0006]

According to a first aspect of the present invention, there is provided a gas leak alarm device comprising a plurality of gas sensor units, and the plurality of gas sensor units can be selectively connected to a gas detection unit. When the connection time of the selected gas sensor unit reaches the set time, a sensor switching mechanism for sequentially selecting another gas sensor unit for switching connection is provided.

According to the first aspect of the present invention, the gas leak alarm can be continuously used for a period close to the total life of the plurality of gas sensors without interrupting the operation of the gas leak alarm. become. In other words, since a plurality of gas sensor units are used while being switched, the use time of each gas sensor unit is shorter than the use period of the gas leak alarm device.Therefore, if each gas sensor unit is used up to the end of its life, almost each gas sensor unit will be used. It is possible to use the gas leak alarm continuously over the total life of the gas sensor unit. Therefore, it has become possible to continuously use the gas leak alarm that exceeds the life of the gas sensor element.

As a result, it is possible to continuously operate the gas sensor element for a period exceeding the service life of the gas sensor element while avoiding a complicated structure of the gas leak alarm and an increase in the unit price.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an example of a gas leak alarm according to the present invention will be described. The gas leak alarm according to the present invention is formed as shown in FIG. 2 and has a plurality of gas sensor units 10 as shown in FIG.
The gas detection unit 1 having a detection circuit 12 for detecting a gas leak based on an input from the controller, an alarm unit 24 for issuing a gas leak alarm based on the detection result of the gas detection unit 1, and the gas sensor unit 10 intermittently operating at a temperature higher than the operating temperature. An alarm controller 2 having a purge processing means 20 for heating the heat, a power supply 3 for supplying power to the gas detector 1 and the alarm controller 2, and a state of the gas leak alarm. The display unit 4 is provided.

The gas detecting section 1 includes a plurality of gas sensor sections 10 using a semiconductor gas sensor for measuring a change in electric conductivity due to gas adsorption on a metal oxide semiconductor surface.
And a temperature compensation circuit 11 composed of a thermistor circuit for correcting the temperature dependency of the semiconductor gas sensor with respect to the output from a selected one of the plurality of gas sensor units 10. The gas sensor unit 10 includes a circuit for applying a two-level AC high-low heater voltage and a sensor voltage.

The plurality of gas sensor units 10 are composed of a first gas sensor unit 10A and a second gas sensor unit 10B. The temperature compensation circuit 11 is connected to the detection circuit 12, and the detection circuit 12 The first gas sensor unit 10A or the second gas sensor unit 10B is configured to be selectively connectable, and is switched to a sensor output determination circuit by a switching command from the alarm control unit 2.

The detection circuit 12 corrects the output of the connected gas sensor unit 10 with the output of the temperature compensation circuit 11 by the sensor output discrimination circuit, and outputs the result of the correction of hydrocarbon gas such as city gas or propane gas. The output voltage of the gas sensor element in the standard state corresponding to the set amount is stored as a reference voltage, and is compared with the output from the detection circuit 12. When the output voltage is equal to or higher than the reference voltage, it is determined that gas leakage has been detected. Then, it is configured to output to the control circuit 22 of the alarm device control section 2.

The alarm control unit 2 includes, as the purge processing means 20, a sensor for controlling a heater voltage by switching between a refresh level voltage and a detection level voltage for purging or refreshing the gas sensor unit 10. A heater control circuit 20a and a control circuit 2 for receiving a gas leak detection output from the detection circuit 12 and outputting an alarm.
2, an alarm unit 24 that issues an alarm based on the output of the control circuit 22, and an operation of the plurality of gas sensor units 10 which are selected sequentially and set for a set time interval (for example, 700 time intervals = about one month intervals). ), The sensor switching mechanism 21 is provided with a sensor switching circuit 21b for selectively selecting one of the plurality of gas sensor units 10 in order to switch the operating power supply, and the sensor switching mechanism 21. Has a heater control switching circuit 21a for supplying electric power from the sensor heater control circuit 20a to a heater of the gas sensor unit 10 to be selected next for a predetermined time.

The sensor heater control circuit 20a temporarily changes the heating temperature of the gas sensor unit 10 to a temperature equal to or higher than a use temperature, and removes miscellaneous gas adhering to the sensitive part of the gas sensor element and dust attached thereto. Applying to the heater of the gas sensor element for a purge process and a refresh process for heating the surface of the sensitive part during a use period or after a short non-use period and heating and activating the surface of the sensitive part after a non-use period. The refresh level voltage,
The voltage of the gas detection level is switched and applied to the heater of the gas sensor element of the gas sensor unit 10. For example, the sensor heater control circuit 20a
Generates, as a heater voltage to the heater of the semiconductor gas sensor of the first gas sensor unit 10A or the second gas sensor unit 10B, an AC voltage of two levels of a refresh level and a detection level for the purging process. And a transformer circuit for causing the These two levels of AC voltages are individually applied to the first gas sensor unit 10A or the second gas sensor unit 10B. The voltage of the detection level is set at 150 to 350 ° C. at the sensitive portion of the gas sensor element.
, And the voltage of the refresh level is higher than this by about 150 ° C. (for example, 30 ° C.).
0-450 ° C).

Under the control of the sensor switching mechanism 21, the sensor switching circuit 21b applies the operating power from the power supply unit to the plurality of gas sensor units 10 for a set time interval (for example, 700 time intervals = about 1). (The two gas sensor units 10 as in the above example).
A and 10B are supplied alternately) when the heater control switching circuit 21a is provided.
The operation of switching the heater voltage to the selected gas sensor unit 10 to the gas detection level in conjunction with the sensor switching operation of the sensor switching circuit 21b, and the operation of the sensor heater with respect to the heater of the selected gas sensor unit 10 Prior to the switching of the gas sensor unit 10 by the sensor switching circuit 21b, the output voltage of the control circuit 20a is switched to a refresh level for a predetermined time and applied to perform the purging operation (the latter). The switching circuit is not shown in FIG. 1).

The purging means 20 applies a heater voltage of a refresh level to the heater of the gas sensor unit 10 to be selected next, for example, for one hour before switching (for example, one hour before the end of life), for example, for one hour. Then, by continuously switching the heater voltage to the gas detection level, the heater voltage can be operated immediately after the switching. The gas sensor unit 10 not selected as the next switching target
If the refresh processing is performed by applying a refresh level voltage to the heater for 5 seconds at regular intervals (for example, every 170 hours), the time required for the purge processing immediately before switching can be reduced. Further, the alarm operation of the alarm unit 24 is temporarily stopped at a set time interval (for example, 100 hour interval) for the selected gas sensor unit 10, and the sensor heater control circuit 20a is controlled to set the refresh level of the refresh level. Refresh processing may be performed by applying a heater voltage to the heater for a certain period of time (for example, 5 seconds) so as to prevent the sensitivity of the gas sensor unit 10 being used from deteriorating. This is because gas leak alarms installed in places where the amount of miscellaneous gas adsorbed on the sensitive part of the gas sensor element tends to increase, such as kitchens that are easily contaminated, are accompanied by the adsorption of miscellaneous gas before the life of the gas sensor element is reached. This is effective because causes such as false information and poor notification can be removed beforehand.

The control circuit 22 controls the sensor heater control circuit 20a and the sensor switching circuit 21b, and transmits an alarm output to the alarm unit 24 based on the input of gas leak detection from the detection circuit 12. It is configured as follows. Further, the control circuit 22 includes a timer 22a having a non-volatile memory that individually accumulates the energization time to the plurality of gas sensor units 10, and the plurality of the plurality of gas sensors 10 based on the integration result of the energization time of the timer 22a. Life determination section 23 of gas sensor section 10 for determining the individual lifespan
And a display judging unit 2 for controlling alarm transmission from the alarm unit.
2b.

In the life determining section 23, the time counting mechanism 2
Based on the integration result of 2a, the service life of each of the plurality of gas sensor units 10 is determined by comparing it with a preset life time (for example, 43800 hours = 5 years).
The integration of the energization time by the time counting mechanism 22a starts from the inspection energization before shipment of the gas leak alarm.

The display judging section 22b controls the contents transmitted to the alarm section 24 based on the judgment result of the life judgment section 23, and controls the display contents of the alarm section 24. For example, when some of the gas sensor units 10 have reached the end of their life, the display of the alarm unit 24 is turned on intermittently, and when all of the gas sensor units 10 have reached their end of life, they are turned on continuously. And so on. When audio is also output as the audio output, the output content is selected.

The alarm section 24 receives a signal from the control circuit 22 and receives a signal from the control circuit 22 to indicate a gas leak.
4a, an alarm speaker 25 for outputting sound, and a yellow LED for indicating the end of life of the plurality of gas sensor units 10.
24b. When receiving from the control circuit 22 a signal indicating that the detection output of the gas sensor unit 10 has exceeded the reference voltage, the red LED 24a is continuously turned on, and at the same time, the alarm speaker 25 emits an alarm sound. It is. This alarm sound is maintained during the gas leak detection of the gas sensor unit 10, and stops when the gas leak is no longer detected. At the same time, the red LED 24a is turned off. For this purpose, the alarm unit 24 is provided with an automatic return function. Further, the yellow LED 24b
When the first gas sensor unit 10, for example, the first gas sensor unit 10A is determined to have reached the end of its life, it is turned on periodically for a short time (for example, one minute), and all the gas sensor units 10 reach their end of life. For example, in the above example including two gas sensor units, the second gas sensor unit 1 is used.
If the life reaches 0B, it is determined that all the gas sensor units have reached the life, and continuous lighting is performed.

The power supply unit 3 includes a transformer circuit 3b for stepping down from a commercial power supply via a surge protection circuit 3a, a rectifying / smoothing circuit 3c for full-wave rectification, and a constant voltage power supply circuit 3d for control power of 5V DC. And the output of the constant voltage power supply circuit 3d is the gas detector 1, the alarm controller 2,
The power is supplied to the power display unit 4a. The power display unit 4a includes:
The red LED 24a and the yellow LED of the alarm unit 24
The display section 4 is formed together with the display section 24b, and includes a green LED 3e which is always lit in a normal state.

One example of a gas leak alarm having the above-mentioned two gas sensor units 10 will be described. An energization test is performed prior to shipment of the gas leak alarm.
From this point, the time integration of the timer 22a is started.
That is, an energization test is performed after resetting the energization time. Then, it is attached to the user's home and started to be used. At this time, the time counting mechanism 22a has accumulated the use time of about 1 hour for both the gas sensor units 10A and 10B. First, the first gas sensor unit 10A is selected and connected to the sensor output determination circuit of the detection circuit 12. A temperature compensation circuit 11 is coupled to the sensor output determination circuit,
The output of the first gas sensor unit 10A is input to the sensor output determination circuit, corrected by the output of the temperature compensation circuit 11, and compared with a reference voltage set in the sensor output determination circuit. If, during this time, the result of the comparison indicates that the corrected output exceeds the reference voltage, it is determined that a gas leak has occurred, a gas leak detection is output to the control circuit 22, and an alarm unit is controlled by the control circuit 22. 24 red LEDs 24
a is turned on continuously, and at the same time
For example, "Do you have a beep, beep, or beep gas?" A sound alert that repeats such a message is issued. If the detection circuit 12 does not detect a gas leak, the sound alarm stops. The red LED 24a
Is turned off under the control of the display determination unit 22b of the control circuit 22 after the above-mentioned sound alarm is stopped. During this time, the use time corresponding to the first gas sensor unit 10A is the time counting mechanism 2
2a. The heater voltage of the gas sensor unit 10 is switched at intervals of 700 hours under the control of the heater control switching circuit 21a. That is, the first gas sensor unit 10A
When 700 hours have elapsed since the start of use of the sensor switching circuit 21b, the sensor switching circuit 21b
Disconnects the first gas sensor unit 10A from the detection circuit 12, and connects the second gas sensor unit 10B to the detection circuit 1.
2, the sensor switching circuit 21b switches the operating power supply to the second gas sensor unit 10B. Prior to this, when 699 hours have elapsed since the start of use of the first gas sensor unit 10A, the second gas sensor unit 1A was used.
The heater voltage of the refresh level is applied to the heater of 0B from the sensor heater control circuit 20a for one hour to perform a purge process, and then the heater voltage is switched to the gas detection level. This is sequentially repeated, and when 699 hours have passed after the switching to the second gas sensor unit 10B, the sensor heater control circuit 20a applies a refresh level heater voltage to the heater of the first gas sensor unit 10A for one hour. A purge process is performed, the connection of the second gas sensor unit 10B to the detection circuit 12 is disconnected, the voltage applied to the heater of the first gas sensor unit 10A is switched to a gas detection level, and the connection to the detection circuit 12 is performed. The sensor switching circuit 21b switches the operating power supply to the first gas sensor unit 10A. As described above, the first gas sensor unit 10A and the second gas sensor unit 10B are alternately used as the sequential selection of the gas sensor unit, and the use corresponding to the first gas sensor unit 10A integrated in the time counting mechanism 22a is performed. When the time reaches the service life of 43800 hours, the service life determining unit 23 determines that the first gas sensor unit 10A has reached the service life, and the control circuit 22
Is controlled by the display determining unit 22b, the yellow LE of the alarm unit 24 is controlled.
D24b starts blinking. Thereafter, when the use time of the second gas sensor unit 10B also reaches 43800 hours, the life determining unit 23 determines that the life of the gas leak alarm has reached the life, and performs the display without switching the gas sensor unit 10. Under the control of the determination unit 22b, the yellow L
The ED 24b is continuously turned on.

With the configuration described above, the life of the gas sensor element is usually five years, whereas if two gas sensor parts are provided, it can be used for ten years. Naturally, if three gas sensor units are provided, they can be used continuously for about 15 years. As described above, a single detection circuit 12 is commonly used for a plurality of gas sensor units, and temperature compensation is performed. The circuit 11 is also the detection circuit 1
2 is common to the plurality of gas sensor units. Therefore, since the circuit configuration is simplified and only the number of gas sensor elements is increased, the shape of the gas leak alarm device may be slightly changed or may not be changed, thereby suppressing an increase in cost. . In addition, since the life of the gas sensor element is displayed by turning on the yellow LED 24b, the safety can be maintained by clearly indicating the replacement time of the gas leak alarm which has been used continuously for a long time.

[Other Embodiments] <1> In the above embodiment, the first gas sensor 10A and the second gas sensor 10
B, the gas sensor unit 10 has been described.
May be three or more, as long as they are sequentially switched and used. For example, if four gas sensor units 10 are provided, it can be used continuously for about 20 years.

<2> In the above-described embodiment, an example is described in which a semiconductor sensor element is used as the gas sensor element of each gas sensor section 10. However, the gas sensor element is of another type such as a contact combustion type gas sensor element. Well,
In addition, a gas sensor of any detection method such as a hot-wire type semiconductor gas sensor element that measures a change in electric conductivity due to gas adsorption on the surface of a metal oxide semiconductor as a change in resistance as viewed from both ends of a platinum wire coil can be used. It can be configured using elements.

<3> In the above embodiment, each gas sensor unit 10 is provided with a single gas sensor element. However, for example, the first sensor element for detecting a leak gas such as a hydrocarbon gas and The gas sensor unit 10 may be configured to include both a second sensor element for detecting carbon monoxide gas generated by incomplete combustion. Further, each gas sensor unit 10 is constituted by a single gas sensor element, the detection level of the sensor heater control circuit 20a is set to two levels, and the heater heating temperature is changed periodically, for example, the gas sensor element When the temperature of the sensitive part is set to 350 ° C., the leaked gas is set to 1
If the configuration is such that the carbon monoxide gas is detected alternately by lowering the temperature to 50 to 200 ° C., two types of gases can be detected using a single semiconductor gas sensor element, and gas leakage and non-gas leakage can be detected. It is possible to warn both of the complete combustion. In this case, the content of the alarm of the alarm unit 24 may be changed. For example, the lighting state of the red LED 24a may be changed, or the distinction may be made by an audio alarm. Further, the content of the alarm sound may be changed depending on the detected density.

<4> In the above-described embodiment, the case where the life of each gas sensor unit 10 is set in advance has been described. However, a sensitivity test is periodically performed using a sample gas so as to deviate from the set sensitivity range. , It may be determined that the life has expired. For example, in the case of a semiconductor gas sensor element, it may be determined that the life has been reached when the alarm level has been reached for a sample gas having a hydrogen concentration of, for example, 0.01%.

<5> In the above embodiment, the yellow LED 24b is turned on intermittently when the service life of the gas sensor unit 10 reaches the first life, and the yellow LED 24b is turned on continuously when all the gas sensor units 10 reach the service life. As described above, such distinction of display is arbitrary, and an LED for display may be arranged for each gas sensor unit 10.

<6> In the above-described embodiment, the description has been given assuming that the life time of the gas sensor unit 10 is 43,800 hours (5 years). However, the above 5 years indicates the quality assurance period of the product. The life reaching time is determined by a period during which the function of the gas sensor element can be maintained.

<7> In the above-described embodiment, the refresh process is also performed periodically (for example, at 700 hour intervals = about one month interval) for 5 seconds on the gas sensor unit 10 not selected as the next switching target. Although an example in which the process is performed has been described, there is no object in the device including the two gas sensor units described in the above embodiment, and even when the device includes three or more gas sensor units, the refresh operation is performed. The processing can be omitted, and may be omitted even when the time interval until the next switching use is short. In particular, when the gas sensor element used in the gas sensor unit 10 does not require the purge process, neither the refresh process nor the purge process need be performed. However, this is an effective measure for a gas leak alarm installed in a place where the amount of miscellaneous gas adsorbed is likely to be large. For example, if the operation of the alarm unit 24 is temporarily stopped at intervals of 170 hours (approximately one week), and a refresh process of about 5 seconds is performed in the meantime, false alarms, poor notification, etc. until the end of the service life can be anticipated. Can be prevented. When two gas sensor elements that do not require a purge process are used, a heater voltage switching circuit for the refresh process or the purge process is omitted, and as shown in FIG. A sensor output determination circuit that includes a first gas sensor unit 10A and a second gas sensor unit 10B and that includes a detection circuit 12 for determining an output from the gas detection unit 1; A switching circuit connected to a discriminating circuit, and a temperature compensation circuit 11 connected to the sensor output discriminating circuit,
The first gas sensor unit 10A and the second gas sensor unit 10B are alternately connected to each other to correct the output from the gas sensor element, and the alarm device control unit 2 operates the two gas sensor units 10A and 10B. A sensor switching circuit 21b for switching the power supply; and a gas leak judging from an output from the detection circuit 11;
A configuration may be provided in which a life determining unit 23 for determining the life of each of the A and 10B is provided, a control circuit 22 for transmitting to the alarm unit 24 is provided, and the power supply unit 3 and the display unit 4 are provided. In this case, in the refresh process of the gas sensor unit 10, the heater voltage may be temporarily increased (for example, for 5 seconds) from the detection level voltage to the refresh level voltage.

<8> In the above embodiment, the sensor switching circuit 21b is
The operating power from the power supply unit is configured to be selectively and sequentially supplied at set time intervals (for example, 700 time intervals = approximately one month interval), and the heater control switching circuit 21a is provided with the sensor switching circuit. In conjunction with the sensor switching operation of 21b,
Although the example in which the selected heater voltage to the gas sensor unit 10 is switched to the gas detection level has been described, the set time is not limited to the above example, and may be, for example, 1000 hours. Further, instead of the set time, the switching may be performed at a time interval according to a change in the detection sensitivity of the gas sensor unit 10. For example, the alarm unit 24 is once disconnected periodically (for example, every three hours), and a sample gas (for example, an inert gas containing 0.05% hydrogen gas) is supplied to the sensitive unit of the gas sensor element. The switching may be determined based on the output of. If the output level by the detection of the sample gas does not reach the alarm level, the alarm unit 24
Need not be disconnected.

[Brief description of the drawings]

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

FIG. 2 is a partially cutaway perspective view of an example of a gas leak alarm according to the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Gas detection part 10 Gas sensor part 21 Sensor switching mechanism 24 Alarm part

Claims (1)

[Claims] 1. A gas leak alarm device comprising: a gas detection unit that detects a gas leak based on an input from a gas sensor unit; and an alarm unit that issues a gas leak alarm based on a detection result of the gas detection unit. And a plurality of the gas sensor units are configured to be selectively connectable to the gas detection unit, and when the connection time of the selected gas sensor unit reaches a set time, another gas sensor unit is sequentially selected. A gas leak alarm equipped with a sensor switching mechanism for switching connection.