JPH1166464A - Gas leak alarm - Google Patents

Abstract

PROBLEM TO BE SOLVED: To attain a continuous operation for a period longer than the life of a conventional gas sensor element for a gas leak alarm which is provided with a gas detection part including a detection circuit that detects the gas leak based on the input of gas sensor part, an alarm part which generates a gas leak alarm according to the result of the gas detection part and a purge processing means which eliminates the adsorbed miscellaneous gas, dust, etc. SOLUTION: A sensor switch mechanism 21 functions to alternatively connect two gas sensor parts 10 to a gas detection part 1 and also to connect with switching the other part 10 to a detection circuit 12 based on the decision result of a life decision part 23 which decides the lives of working parts 10. Then the purge processing is periodically applied also to the non-selected part 10. It's more desirable to decides the lives of two parts 10 based on the working periods of time of both parts 10 which are individually counted.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a gas detector provided in a general household in a room where gas appliances are used and provided with a detection circuit for detecting a gas leak from an input from a gas sensor, An alarm unit for issuing a gas leak alarm according to the result, and a purging unit for intermittently heating the gas sensor unit to a temperature equal to or higher than a use temperature to perform a purging process to remove adsorbed miscellaneous gas and attached dust and the like. It relates to a gas leak alarm.

[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-mentioned conventional structure, 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]

[Means for Solving the Problems]

[Characteristic configuration] The characteristic configuration of the gas leak alarm according to claim 1, wherein a plurality of gas sensor units are provided, and the plurality of gas sensor units are configured to be selectively connectable to a gas detection unit. A sensor switching mechanism that includes a life determining unit that determines the life of the unit, selects another gas sensor unit from among the plurality of gas sensor units based on the determination result of the life determining unit, and sequentially switches and connects to the detection circuit. And the purge processing means is configured to periodically perform a purge process even on an unselected gas sensor unit.

In a second aspect of the present invention, there is provided a gas leak alarm device comprising a time counting mechanism for individually counting the use time of the plurality of gas sensor units in the first feature configuration, wherein the time counting result of the time counting mechanism is provided. Is configured to determine that the service life has been reached when the service life of the gas sensor has been reached.

[Function and Effect of Characteristic Configuration] The above-mentioned claim 1
According to the described characteristic configuration, it becomes possible to operate the gas leak alarm continuously over a total period of the life of the gas sensor unit provided substantially. In other words, even if the life of the gas sensor element of one gas sensor unit has expired, the subsequent operation can be performed by selecting the next gas sensor unit and performing a purge process in advance and switching and connecting to the detection circuit. In addition, since there is only one detection circuit, there is an advantage that it can be manufactured at low cost without complicating the structure. Therefore, it has become possible to continuously use the gas leak alarm that exceeds the life of the gas sensor element.

According to the second aspect of the present invention, the life time is not erroneously determined even if the purging process is performed on each gas sensor unit in a timely manner. Can be used effectively. Therefore,
Since the life time of each gas sensor unit is used without waste, all the gas sensor units can be used effectively.

As a result, it is possible to continuously operate the gas sensor device constituting the gas sensor unit over a period of time that exceeds the service life of the gas sensor while avoiding a complicated structure and an increase in the unit price of the gas leak alarm device.

[0011]

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 as shown in FIG.
A plurality of gas sensor units 10, a gas detection unit 1 including a detection circuit 12 for detecting gas leak based on an input from the gas sensor unit 10, and an alarm unit 24 for issuing a gas leak alarm based on the detection result of the gas detection unit 1. An alarm control unit 2 including a purging unit 20 for intermittently heating the gas sensor unit 10 to a temperature equal to or higher than a temperature, and a power supply unit for supplying power to the gas detection unit 1 and the alarm control unit 2 3 and a display unit 4 for displaying the state of the gas leak alarm.

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 the surface of the metal oxide semiconductor.
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 include 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 An alternative connection can be made to the first gas sensor unit 10A or the second gas sensor unit 10B, and is switched to a sensor output discrimination 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 by the sensor output discrimination circuit based on the output of the temperature compensation circuit 11, 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 switching and controlling a heater voltage 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 a sensor switching mechanism 21 for selectively selecting and switching the operation of the plurality of gas sensor units 10. Reference numeral 21 denotes a sensor switching circuit 21b for selectively selecting an operation power source from the plurality of gas sensor units 10 and a heater for refreshing the gas sensor unit 10 to be purged from the sensor heater control circuit 20a. It comprises a heater control switching circuit 21a for supplying a voltage 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. The voltage of the refresh level and the voltage of the gas detection level applied to the heater of the gas sensor element for the refresh process for heating and activating the surface of the sensitive portion during the purge process and after use or after a short non-use period. It is configured to switch and apply the voltage to the heater of the gas sensor element of the gas sensor unit 10. For example, the sensor heater control circuit 20
a is a high-low two-level AC voltage of a refresh level and a detection level for the purging process 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. It consists of a transformer circuit to generate. These two levels of AC voltages are individually selected and applied to the first gas sensor unit 10A or the second gas sensor unit 10B. The voltage of the detection level is set to heat the sensitive part of the gas sensor element to 150 to 350 ° C., and the voltage of the refresh level is set to a voltage higher by about 150 ° C. (for example, 300 to 450 ° C.). You.

Under the control of the control circuit 22, the sensor switching circuit 21b is configured to selectively select and supply operating power from a power supply unit to the plurality of gas sensor units 10. And the heater control switching circuit 21
a is an operation for 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;
2, the operation of switching the output voltage of the sensor heater control circuit 20a to the refresh level for a predetermined time and applying the same to the heater of the gas sensor unit 10 for purging or refreshing the gas sensor element based on the command from (The latter switching circuit is not shown in FIG. 1).

The control circuit 22 controls the sensor heater control circuit 20a and the sensor switching circuit 21b, and sends an alarm output to the alarm section 24 based on the input of gas leak detection from the detection circuit 12. It is configured to do so. 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; 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). When one of the plurality of gas sensor units 10, for example, the first gas sensor unit 10A reaches the end of its life, based on the determination result of the life determining unit 23, the sensor switching mechanism 21 Another gas sensor unit 10, for example, the second gas sensor unit 10 </ b> B is selected and selected from the plurality of gas sensor units 10, and a command is issued to switch to the detection circuit 12. 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 judges and controls the contents transmitted to the alarm section 24 based on the judgment result of the life judging 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 on the alarm unit 24 is blinking, and when all of the gas sensor units 10 have reached their end of life, they are turned on continuously. Perform the operation. When audio is also output as the audio output, the output content is selected.

Further, the purge processing means 20 temporarily stops the alarm operation of the alarm unit 24 at a predetermined time interval (for example, 1000 hour interval) for the selected gas sensor unit 10, and controls the sensor heater control. Instruct the circuit 20a to apply the heater voltage of the refresh level to the heater for a predetermined time (for example, 5 seconds) (refresh processing).
To prevent deterioration of the sensitivity of the gas sensor unit 10 during use,
Immediately before the life of the gas sensor unit 10 in use (for example, one hour before the life reaches), a heater voltage of a refresh level is applied to the heater of the gas sensor unit 10 selected next for one hour, for example. By performing a purging process prior to the switching and subsequently switching the heater voltage to the gas detection level, the heater voltage can be activated immediately after the switching. The purging means 20 is
If the refresh process is performed on the unselected gas sensor unit 10 periodically (for example, at 700 hour intervals = about one month interval) for 5 seconds, the time required for the purge process immediately before switching can be reduced.

The alarm unit 24 receives a signal from the control circuit 22 and receives a signal from the control circuit 22.
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. In other words, in other words, in the case where the second gas sensor unit 10B includes two gas sensor units as in the above-described example, the second gas sensor unit 10B is also turned on continuously when it reaches the end of its life.

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.

A description will be given of one example of a gas leak alarm having the configuration including the two gas sensor units 10 described above. An energization test is performed before 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,
If the output after the temperature compensation exceeds the reference voltage,
It determines that the gas is leaking and outputs a gas leak detection to the control circuit 22.
D24a is turned on continuously, and at the same time, the alarm speaker 25 is turned on.
From, for example, "Pip-pip-pip-pip-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 determining unit 22b of the control circuit 22 after the stop of the sound alarm. During this time, the usage time corresponding to the first gas sensor unit 10A is accumulated in the timer 22a, and at the same time, the sensor heater is controlled for the second gas sensor unit 10B by the control of the heater control switching circuit 21a at intervals of 700 hours. A refresh level voltage is applied from the control circuit 20a to the heater for 5 seconds to perform a refresh process. The time of this refresh processing is added to the time counting mechanism 22a for the second gas sensor unit 10B. On the other hand, the first gas sensor unit 10
For A, the operation of the alarm unit 24 is stopped and the refresh process is performed for 5 seconds at 1000-hour intervals under the control of the heater control switching circuit 21a. Further, the control circuit 22 determines that the usage time of the first gas sensor unit 10A is 4 hours.
When it is detected that the time has reached 3799 hours, the heater control switching circuit 21a is controlled to set the refresh level voltage to 1 for the heater of the second gas sensor unit 10B.
Purge processing is performed by applying time, and the heater voltage is subsequently switched to the gas detection level.
The power circuit is switched to the second gas sensor unit 10B by b. At the same time, intermittent lighting of the yellow LED 24b is started. Thereafter, the first gas sensor section 10A
Similarly to the above, under the control of the heater control switching circuit 21a, the operation of the alarm unit 24 is stopped and the refresh process for 5 seconds is performed at 1000-hour intervals. The usage time of the second gas sensor unit 10B after the switching is 4
When it reaches 3800 hours, it is determined that the life of the gas leak alarm has reached its end, and the yellow LED 24b is continuously turned on without switching the gas sensor unit 10.

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 15 years. As described above, a single detection circuit 12 is commonly used for a plurality of gas sensor units, and a temperature compensation circuit is used. 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, safety can be maintained by clearly indicating the time for replacing the gas leak alarm which has been used continuously for a long time.

[Another Embodiment] <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 has been 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,
For the detection method, for example, a hot-wire semiconductor gas sensor element or any other gas sensor element that measures a change in electric conductivity due to gas adsorption on the surface of the metal oxide semiconductor as a change in resistance value as viewed from both ends of the platinum wire coil is used. Can be configured.

<3> In the above embodiment, each gas sensor unit 10 is provided with a single gas sensor element. However, for example, a first sensor element for detecting a leak gas such as a hydrocarbon gas and a 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 The temperature of the sensitive part is set to 350 ° C., and the leaked gas is supplied to the sensitive part at a temperature of 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-described embodiment, the yellow LED 24b is turned on intermittently when the service life of the gas sensor unit 10 reaches the end, and the yellow LED 24b is turned on continuously when all the gas sensor units 10 reach the end of 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 refresh process is also performed on the unused gas sensor unit 10 periodically.
Immediately before reaching the life of 0, the next selected gas sensor unit 10
Other than the above-described purge processing performed for the above, the refresh processing may not be performed. In this case,
If there is a long unused period, it may be better to extend the purging time to about one day.
In any case, the purge processing time shown in the above embodiment is merely an example, and the purge processing time is set according to the characteristics of the gas sensor element used. In the case where two gas sensor elements that do not require the purge process are used, the gas detection unit 1 includes, for example, the gas detection unit 1 as shown in FIG. 1 in which the heater voltage switching circuit for the refresh process or the purge process is omitted. A first gas sensor unit 10A and a second gas sensor unit 10B are provided, and a detection circuit 12 is provided with a switching circuit and a sensor output determination circuit connected to a temperature compensation circuit 11, and the sensor output determination circuit is provided with the first gas sensor unit. 10A and one of the second gas sensor units 10B are connected so as to correct the output from the gas sensor element.
A sensor switching circuit 21b for switching the operating power supply between the sensors A and 10B, and a life determining unit for determining gas leakage from the output from the detection circuit 11 and determining the life of each of the gas sensor units 10A and 10B. 23, a control circuit 22 for transmitting a signal to the alarm unit 24 may be provided, and the power supply unit 3 and the display unit 4 may be provided. in this case,
The refresh process can also be performed by temporarily (for example, 5 seconds) increasing the heater voltage from the detection level voltage to the refresh level voltage.

<7> In the above embodiment, the gas sensor unit 10 that is not selected is also periodically (for example, 700
Although an example in which the refresh process is performed for 5 seconds (time interval = approximately one month interval) has been described, the interval of the refresh process may be a short interval (for example, 170 hours (Interval = about one week interval) in some cases.

<8> In the above-described embodiment, the description has been made 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.

[Brief description of the drawings]

FIG. 1 is a block diagram of an embodiment 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 12 Detection circuit 20 Purge processing means 21 Sensor switching mechanism 22a Clocking mechanism 23 Life judgment part 24 Alarm part

Claims (2)

[Claims] A gas detection unit that detects a gas leak based on an input from a gas sensor unit; an alarm unit that issues a gas leak alarm based on a detection result of the gas detection unit; And a purging means for intermittently heating the unit to perform a purging process to remove adsorbed miscellaneous gas and adhering dust and the like. A gas sensor unit is configured to be alternatively connectable to the gas detection unit, a life determination unit that determines the life of the gas sensor unit in use is provided, and the plurality of gas sensors are provided based on a determination result of the life determination unit. A sensor switching mechanism for selecting another gas sensor unit from among the units and sequentially switching connection to the detection circuit is provided, and the purge processing means is provided for an unselected gas sensor unit. Gas leak alarm even are configured to perform the regular purge process by. 2. A time-measuring mechanism for individually measuring the use time of the plurality of gas sensor units, and when the time-measured result of the time-measuring unit reaches the life time of the gas sensor unit, it is determined that the life has been reached. The gas leak alarm according to claim 1, wherein the gas leak alarm device comprises the life determining unit.