JP4989369B2 - Gas alarm - Google Patents

Description

The present invention relates to a gas leak alarm that switches a semiconductor gas detection element to a plurality of temperatures and heats it, and determines the presence or absence of a gas leak based on different types of gas detection outputs of the gas detection element when heated to each temperature. More particularly, the present invention relates to a gas alarm device that injects a check gas during a transition from power-on to a normal monitoring state to check that a gas detection element operates normally.

  In general homes and the like, gas alarms that detect gas leaks and issue alarms are widely used. Generally, this gas alarm device includes a gas detection element, and is configured to determine the presence or absence of gas leakage based on a change in the output of the gas detection element.

  In recent years, gas alarms have been proposed in which gas leaks of a plurality of types of gases, such as methane gas and CO gas, can be detected by a single gas detection element in order to reduce the cost of the equipment.

  In such a gas alarm device, the gas detection element is switched to two types of temperatures suitable for detection of methane gas and CO gas, which are detection target gases, and is heated to change the output of the gas detection element heated to each temperature. Based on this, the presence or absence of gas leakage is determined.

  By the way, when the gas alarm is installed in the dwelling unit and gas leakage monitoring is started, a predetermined inspection time is set after the commercial alarm power supply is supplied to the gas alarm, for example. The actual inspection (inspection gas) is sprayed on the gas detection element of the gas alarm device, and the operation inspection work is performed to confirm that the gas leak alarm is actually issued.

  As a method for checking the operation of the gas alarm device with the actual gas, the gas inlet is sucked into a gas stove flame, and the gas is sucked and sprayed to the sensor portion of the gas alarm device. Specifically, the operation check of methane gas is inhaled from the root of the flame of the gas stove, and the operation check of CO gas is inspected separately by inhaling gas from the center of the gas stove flame.

  However, depending on the site where the gas alarm is installed, the construction of the gas and the opening of the gas are not completed, and there are cases where the inspection must be carried out with a portable instrument such as a commercially available gas lighter. However, since methane gas cannot be extracted from the flame of the gas lighter, there is a problem that only the CO side gas can be checked.

In order to solve this problem, an inspection method using hydrogen gas or CO gas, which is easy to use, as an actual gas has been proposed. In this inspection method, in order to detect charcoal methane gas, the heater control for heating the semiconductor gas detection element to about 400 ° C. is performed, and the detection signal of the gas detection element is read and processed at a stable timing at 400 ° C. Using the fact that there is a region showing high sensitivity to hydrogen gas, for example, in the temperature region in the middle of reaching about 80 ° C. for detecting CO gas from 400 ° C. by turning off the heater, high sensitivity to hydrogen gas is exhibited At the timing, the detection signal from the gas detection element is read as a detection signal by the hydrocarbon gas, and when a predetermined threshold value is exceeded, a gas leak alarm is issued and it is determined that the hydrocarbon gas has normally operated.
JP 2004-038660 A JP 2002-269657 A JP 2004-192339 A

  However, in such a conventional method for checking a gas alarm that uses hydrogen gas as an actual gas to check its operation, the heater energization time timing for stabilizing the temperature of the semiconductor gas detection element at 400 ° C. The detection hydrogen gas is detected at different timings, and multiple detection timings must be set and switched for the heater energization time, which complicates the software that executes detection timing control processing. There is.

  In addition, because the detection is not at the detection timing of methane gas by energizing the heater, but at another timing that is highly sensitive to hydrogen gas, the operation at the detection timing of hydrocarbon gas cannot be accurately simulated, It is not an original operation check, and it cannot be said that reliability is sufficient as an operation check for hydrocarbon gas.

  Furthermore, the hydrogen gas concentration obtained from the flame of the lighter varies greatly depending on the sampling point, and the threshold may not be reached at the detection timing of the hydrogen gas, and repeated inspection work must be performed.

  An object of this invention is to provide the gas alarm which improves the reliability by enabling the operation inspection using real gas other than detection object gas, without changing a detection timing.

The present invention provides a gas alarm. The present invention
The first detection condition for detecting the first detection target gas and the second detection condition for detecting the second detection target gas are alternately set at a predetermined time interval in a single semiconductor gas detection element. And a gas alarm device for judging and alarming a gas leak by comparing a detection signal from the gas detection element obtained in the setting state of the first detection condition or the second detection condition with respective predetermined thresholds. ,
When setting the inspection mode, the threshold for determining the gas leakage of the first detection target gas is changed to a predetermined inspection threshold for determining the gas leakage of the inspection gas including the second detection target gas without including the first detection target gas. A threshold setting update unit,
An operation check unit that warns of a gas leak of the first detection target gas when the detection signal from the gas detection element according to the setting of the first detection condition exceeds the check threshold during the setting of the check mode in which the check gas is injected. When,
It is provided with.

In another embodiment of the present invention, the first detection condition for detecting the first detection target gas and the second detection condition for detecting the second detection target gas are detected in a single gas detection element. Are alternately set at predetermined time intervals, and a gas leak is determined by comparing the detection signal from the gas detection element obtained in the setting state of the first detection condition or the second detection condition with each predetermined threshold value. In the gas alarm that alarms,
When the inspection mode is set, the inspection gas of the detection signal from the gas detection element is injected when the first detection condition is set for the inspection gas mainly containing the second detection target gas without including the first detection target gas. A threshold value setting unit for setting a threshold value for determining gas leakage from a change amount from an initial value before performing a predetermined threshold value change amount;
During the setting of the inspection mode in which the inspection gas is injected, when the change amount from the initial value of the detection signal from the gas detection element by the setting of the first detection condition exceeds the threshold change amount, the first detection target gas is changed. An operation check section that warns of gas leakage,
It is provided with.

  Here, the first detection target gas is methane gas, the second detection target gas is CO gas, and the inspection gas does not include methane gas, and combustion is taken from a gas lighter flame in which CO gas and hydrogen gas are mixed. Gas.

The present invention provides a method for checking a gas alarm. The present invention
A first detection condition including a first heater control value and a first detection timing for detecting the first detection target gas in a single gas detection element, and a second heater control for detecting the second detection target gas The value and the second detection condition including the second detection timing are alternately set at a predetermined time interval, and the detection signal from the gas detection element obtained in the first detection condition or the setting state of the second detection condition is set to each In the inspection method of a gas alarm device that judges and warns of gas leakage by comparing with a predetermined threshold,
When setting the inspection mode, the threshold for determining the gas leakage of the first detection target gas is changed to a predetermined inspection threshold for determining the gas leakage of the inspection gas including the second detection target gas without including the first detection target gas. A threshold setting step,
Operation check that warns of a gas leak of the first detection target gas when the detection signal from the gas detection element by the setting of the first detection condition exceeds the inspection threshold during the setting of the inspection mode in which the inspection gas is injected Steps,
It is provided with.

In another aspect of the present invention, the first detection condition including the first heater control value and the first detection timing for detecting the first detection target gas in a single semiconductor gas detection element, 2 The second heater control value for detecting the detection target gas and the second detection condition including the second detection timing are alternately set at a predetermined time interval, and the first detection condition or the second detection condition is set. In the inspection method of the gas alarm device for judging the gas leak by comparing the detection signal from the obtained gas detection element with each predetermined threshold value, and alarming,
Before the inspection gas of the detection signal from the gas detection element when the first detection condition is set for the inspection gas including the second detection target gas without including the first detection gas when the inspection mode is set . A threshold value setting step for setting a threshold value for determining gas leakage from the change amount from the initial value to a predetermined threshold change amount;
During the setting of the inspection mode in which the inspection gas is injected, when the change amount from the initial value of the detection signal from the gas detection element by the setting of the first detection condition exceeds the threshold change amount, the first detection target gas is changed. An operation check step that warns of gas leaks;
It is provided with.

According to the present invention, the first detection target gas, for example, when checking the checking operation of the gas detection element with respect to methane gas, the inspection gas taken from the flame of a gas lighter comprising CO gas and hydrogen gas without the methane gas Even if it is used, the detection threshold of methane gas to be inspected is not changed, and the threshold for judging gas leakage is simply changed to the threshold for inspection, so no software changes are required and it can be handled easily. .

Also and for reviewing operation for alarm to determine the gas leak at the detection timing of the inspection target e.g. methane, since it operates inspected without changing the detection timing, accurately simulate the detection alarm operation of the actual methane gas This improves the reliability of inspection.

Further, in the composite type gas detector methane gas and CO gas, at the inspection gas containing CO collected from a gas lighter flame, it can be tested simultaneously detecting alarm operation of the detection alarm operation and CO gases methane gas, It is possible to improve the inspection reliability in the combined type gas alarm.

Furthermore, inspection gas taken from the gas lighter flame was a mixed gas of CO gas and hydrogen gas, the concentration ratio varies from collection, in the detection timing of the methane gas, the sum of the CO gas and hydrogen gas since reacting the gas concentration without being affected by the mixing ratio, the inspection of the detection alarm operation of the methane gas the combustion gas and the actual gas can be stably performed.

  FIG. 1 is an explanatory view showing an embodiment of an alarm device according to the present invention. In FIG. 1, the alarm device 10 performs a combined gas leak alarm in which the first detection target gas is methane gas and the second detection target gas is CO gas.

  The alarm device 10 is provided with a fire detector 14, a gas detector 16, a speaker 18, a fire alarm lamp 20, a power lamp 22, a CO alarm lamp 24 and a methane alarm lamp 26 in a substantially box-shaped housing 12.

  The fire detection unit 14 is a fire detection unit that detects a temperature due to a fire using a thermistor, or a fire detection unit that detects a fire using a scattered light smoke detection unit. The gas detector 16 detects CO gas or methane gas by a built-in gas detection element.

  The speaker 18 outputs an alarm by a voice message when a fire is detected or a gas leak is detected. The fire warning light 20 blinks or lights up when a fire is detected by the fire detection unit 14.

  The power lamp 22 is lit when the commercial AC 100V is turned on to the alarm device 10. The CO alarm lamp 24 blinks or lights up when the gas detector 16 detects a gas leak of CO gas. Further, the methane alarm lamp 26 blinks or lights up when the gas detector 16 detects a gas leak of methane gas.

  FIG. 2 is a circuit block diagram showing the functional configuration and circuit configuration of the alarm device 10 of FIG. In FIG. 2, the alarm device of the present embodiment has a detection circuit unit 28 connected to a CPU 30, and further connected to the CPU 30 is a non-volatile memory 32, a display unit 34, and an audio output unit 36 including a speaker 18. Has been. In FIG. 2, the constituent elements for the fire detection function are omitted.

The detection circuit unit 28 is provided with a gas sensor 38, and the gas sensor 38 is provided with a gas detection element 40 and a heater 42. For the heater 42, the transistor 44, the heater driving circuit is provided consisting of resistors 46 and 48, the transistor 4 4 on the heater control signal E2 from the CPU 30, the off, to switch the energization stopping the energization of the heater 42 I have to.

In addition, a detection circuit including a transistor 50 and detection resistors 52 and 54 is provided for the gas detection element 40 provided in the gas sensor 38, and is detected when the transistor 50 is turned on / off by a detection resistance switching signal E3 from the CPU 30. and to switch the presence or absence of parallel connection of the detecting resistor 5 2 to the resistance 54.

  The gas detection element 40 detects methane gas or CO gas. When detecting methane gas, the transistor 44 is turned on and off at a constant duty (ON: OFF 146 μs: 4 ms) by the heater control signal E2 of the CPU 30, the temperature of the heater 42 of the gas sensor 38 is controlled, and the gas detection element 40 is turned on. The detection temperature HT1 is heated to, for example, HT1 = 400 ° C.

  On the other hand, when detecting the CO gas, the temperature of the heater 42 of the gas sensor 38 is controlled by turning off the transistor 44 by the heater control signal E2, and the methane gas detection temperature HT1 = 400 ° C. CO gas is detected at a CO gas detection temperature HT2, for example, HT2 = 80 ° C.

  In synchronization with the temperature control switching of the heater 42 of the gas sensor 38 by the transistor 44, the detection resistors 52 and 54 are switched by the transistor 50 for the gas detection element 40. Here, the resistance value of the detection resistor 52 is R1, the resistance value of the detection resistor 54 is R2, and the resistance value of the gas detection element 40 is Rx.

  First, at the time of detecting methane gas, the transistor 50 is turned on by a detection resistance switching signal E3 from the CPU 30, and the detection resistors 52 and 54 are connected in parallel to the gas detection element 40. Therefore, if the power supply voltage Vcc for the detection circuit unit 28 is Vcc = 5 volts, for example, the detection voltage E1 from the gas detection element 40 for the CPU 30 is the parallel resistance (R1 // R2) of the detection resistors 52 and 54 and the gas detection element. It is determined by the divided voltage of 40 resistance value Rx. That is,

となる。

It becomes.

  On the other hand, when detecting CO gas, the transistor 50 is turned off by the detection resistance switching signal E3 from the CPU 30, only the detection resistance 54 is connected to the gas detection element 40, and the divided voltage of both is output to the CPU 30 as the gas detection signal E1. Is done. That is, the gas detection voltage E1 at the time of CO gas detection with the transistor 50 turned off is

となる。

It becomes.

  In this embodiment, the threshold value is set so as to issue an alarm at about 3000 ppm for methane gas, and the resistance value Rx of the gas detection element 40 heated to HT1 = 400 ° C. by the heater 42 at that time is Rx = about 0.5 kΩ.

  On the other hand, the resistance value Rx of the gas detection element 40 at a methane gas detection temperature HT1 = 400 ° C. in normal air in which no methane gas is present is about Rx = 6 kΩ. That is, in the gas detection element 40, when a resistance value of about 6 kΩ in a steady state changes to about 0.5 kΩ, an alarm state is detected in which a gas leak of methane gas is detected.

  On the other hand, for CO gas, a threshold is set so that a gas leak alarm is issued at about 150 ppm. The resistance value Rx of the gas detection element 40 at the CO gas detection temperature HT2 = 80 ° C. for detecting the CO gas is about 10 kΩ. On the other hand, in normal air where no CO gas exists, the resistance value Rx of the gas detection element 40 at HT1 = 80 ° C. is about 1 MΩ. That is, when the resistance value of 1 MΩ in a steady state of the gas detection element 40 at the CO gas detection temperature T2 = 80 ° C. changes to 10 kΩ, a CO gas gas leakage alarm is performed.

Specifically, assuming that the power supply voltage Vcc = 5 volts, the resistance value Rx = 0.5 kΩ of methane gas 3000 ppm, and the resistance value Rx = 6 kΩ in normal air, the detection voltage E1 of methane gas output from the gas detection element 40 is E1 = 1.12V from the equation (1)
It becomes.

Similarly, the detection signal E1 from the gas detection element 40 when the gas concentration of CO gas is 150 ppm is the power supply voltage Vcc = 5 V, the resistance Rx = 10 kΩ of the gas detection element 40 at CO 150 ppm, and the resistance Rx = 1 MΩ in the steady state. (2) From the formula, E1 = 2.5V
It becomes.

  Further, the CPU 30 controls the heater temperature control signal E2 for the detection circuit unit 28 at the timing shown in the time chart of FIG. The heater control signal E2 in FIG. 3 controls the transistor 44 to be turned on and off for the time T1 preceding the cycle T0 to heat the gas detection element 40 to the methane gas detection temperature HT2 = 400 ° C. At the timing of the detection point 78, the detection voltage E1 from the gas detection element 40 is taken in as a methane gas detection signal by the AD converter of the CPU 30.

  Subsequently, the transistor 44 is turned on and off by the heater control signal E2 for T2 time to cool the gas detection element 40 to the CO gas detection temperature HT1 = 80 ° C., and the last CO detection point 80 in T2 time. At this timing, the detection voltage E1 of the gas detection element 40 is taken in as a CO gas detection signal by the AD converter of the CPU 30.

  Here, the T1 time for controlling the heater to overheat to HT1 = 400 ° C. when methane gas is detected is, for example, T1 = 5 seconds, and the time T2 for controlling the heater to be HT2 = 80 ° C. when CO gas is detected is T2 = 15. Therefore, one cycle T0 for detecting methane gas and detecting CO is T0 = 20 seconds.

Referring again to FIG. 2, CPU 3 0 as functions realized by executing a program, the gas signal processing unit 56, the heater control unit 58, arithmetic unit 60, a timer 62, inspection processing unit 64 is provided, further inspection The processing unit 64 is provided with a threshold setting unit 66 and an operation checking unit 68.

  The gas signal processing unit 56 takes in the detection signal E1 from the gas detection element 40 provided in the detection circuit unit 28 by the AD converter at each timing of the methane detection point 78 and the CO detection point 80 shown in FIG. The presence or absence of gas leakage is determined by comparing the detected voltage with the respective threshold values.

  The heater control unit 58 outputs the heater control signal E2 shown in FIG. 3 to the transistor 44 provided in the detection circuit unit 28. After the transistor 44 is turned on and off, the heater 42 is heated to the methane gas detection temperature HT1 = 400 ° C. And the heater 42 is switched to the CO detection temperature HT2 = 80 ° C.

  At the same time, the heater control unit 58 also detects the detection resistance switching signal E3 by synchronizing with the heater control signal E2, turning on the transistor 50 simultaneously with the turning on of the transistor 44, and turning off the transistor 50 simultaneously with turning off the transistor 44. The connection of the resistors 52 and 54 to the gas detection element 40 is switched. Furthermore, the calculation part 60 performs various processes such as gas detection.

  The inspection processing unit 64 operates for a predetermined time, for example, 25 minutes after the power is turned on by supplying commercial AC 100V to the alarm device 10, and performs an inspection operation for detecting gas leaks with respect to methane gas and CO gas using the inspection gas collected from the gas lighter. Make it possible to do.

  The threshold setting unit 66 provided in the inspection processing unit 64 changes the threshold for determining gas leakage of methane gas (first detection target gas) to a predetermined inspection threshold when setting the inspection mode. That is, gas leakage from the detection voltage at the detection timing of methane gas with respect to inspection gas containing hydrogen gas, not including methane gas collected from the flame of a commercially available gas lighter, for example, which is used as actual gas at the time of inspection. Change to a predetermined inspection threshold value to be determined.

  The operation check unit 68 is a gas detection element in a setting state of methane gas temperature HT1 = 400 ° C. by energization of the heater 42 for detecting methane gas during the setting of the check mode in which the check gas collected from the flame of the gas lighter is injected. Even when the detection voltage E1 obtained from 40 exceeds the inspection threshold changed by the threshold setting unit 66, even the inspection gas obtained from the flame of a commercial gas lighter made of a mixed gas of CO gas and hydrogen gas, Judged as methane gas leak and output a gas leak alarm. The processing function of the inspection processing unit 64 will be further clarified in the later description.

The nonvolatile memory 32 provided in the CPU 30 stores programs and parameters necessary for various processes such as gas detection. The display unit 34 is provided with the fire alarm lamp 20, the power lamp 22, the CO alarm lamp 24, and the methane alarm lamp 26 of FIG. 1, and these indicator lamps blink or light up. The audio output unit 36 connects the speaker 18 and outputs an alarm such as a fire alarm or a gas leak alarm from the speaker 18 by an audio message or the like.

  FIG. 4 is a time chart showing the mode transition when the power is turned on in the present embodiment. FIG. 4A shows a power supply, and shows the passage of time with 0 minutes as the timing at which the commercial AC100V power supply is turned off at an arbitrary timing.

FIG. 4B shows the mode control. The activation mode 70 is entered for T1 = 1 minute after the power is turned on. In the activation mode 70, the gas detection element is stabilized and the initialization diagnosis process in the CPU 30 in FIG. And when it starts normally, it transfers to the gas lighter inspection mode 72 which becomes T2 = 3 minutes from 1 minute to 4 minutes.

  In the gas lighter inspection mode 72, the threshold value setting unit 66 shown in the CPU 30 in FIG. 2 extracts the threshold value for detecting methane gas at the normal time from, for example, a flame of a commercially available gas lighter used as an actual gas at the time of inspection. In this mode, the inspection threshold value for judging gas leakage is detected from the detection voltage at the methane gas detection point for the inspection gas containing CO gas and hydrogen gas.

  In the gas lighter inspection mode 72, the normal threshold value is used as it is for the CO gas, and the accumulation time in the normal CO gas detection process is canceled to zero hours.

  That is, in the present embodiment, for CO gas leak detection, for example, two threshold values, a low concentration alarm level and a high concentration alarm level, are set as the CO gas concentration threshold value. If the alarm level is high, the CO gas leakage alarm is issued after accumulating for 3 minutes.

  Regarding the CO gas accumulation detection function, in the gas lighter inspection mode 72, the CO gas accumulation time is set to 0 hour. Therefore, in the inspection mode, the CO gas has a low concentration alarm level or a high concentration alarm level. When any one of the above thresholds is exceeded, a CO gas leak alarm is immediately issued, and the trouble due to the alarm delay due to the accumulation time is eliminated.

When 4 minutes have elapsed since the power was turned on, the mode is switched to the normal inspection mode 74 over T3 = 21 minutes. In the normal inspection mode 74, the change to the inspection threshold for methane gas by the threshold setting unit 66 of FIG. 2 is canceled and becomes a normal threshold, and in this state, methane extracted from a conventional gas stove, CO and to perform the operation test of the gas, similar to the gas lighter inspection mode 72, in the normal inspection mode 74, the storage time of the CO gas leakage is zero hours is reset. When 25 minutes have elapsed since the power was turned on, the normal monitoring mode 76 is entered.

  FIG. 5 is a time chart showing the heater control and the detection signal from the gas detection element in the gas lighter inspection mode of this embodiment. At the same time as entering the gas lighter inspection mode 72, the CO gas collected from the flame of the gas lighter. Inspection gas including hydrogen gas is injected.

  FIG. 5A shows the heater control signal, FIG. 5B shows the detection signal of the gas detection element, and FIG. 5C shows the mode.

5B is inverted by reading the detection signal E1 from the detection circuit unit 28 of FIG. 2 by the AD converter of the CPU 30 (Vcc-E1).
Imported after converting to. Therefore, the detection signal is a signal that increases in proportion to the increase in gas concentration. For this reason, the detection signal E1 in FIG. 2 is a signal that decreases with an increase in gas concentration, but the detection signal in FIG. 5B becomes a signal that increases in accordance with the gas concentration by the inversion process.

  The detection signal in FIG. 5B is read by the CPU 30 at the timing of the methane detection point 78 and the CO detection point 80 shown in FIG. 3 when the heater control signal in FIG. 5A is turned on and off. , A2, A3, A4, A5, and CO gas is read at the timings B1, B2, B3, B4.

  Here, at the same time when the gas lighter inspection mode 72 is entered from the start mode 70 of FIG. 5C, inspection gas containing CO gas and hydrogen gas extracted from the flame of the gas lighter is injected into the gas detector 16 of FIG. Therefore, when the gas lighter inspection mode 72 is entered, the methane gas detection signals and the CO gas detection signals at the detection points A1 and B2 in normal air in the startup mode 70 increase to values corresponding to the injection of the inspection gas.

  In other words, by the injection of inspection gas containing CO gas and hydrogen gas, the methane gas detection timing is in the case of the start mode 70 in which the detection signals are sequentially in normal air as indicated by the detection points A2, A3, A4, A5. Compared to the increase. On the other hand, as for CO gas, since the inspection gas contains CO gas as a main component, the detection signal is greatly increased as indicated by detection points B2, B3, and B4.

In the present embodiment, at the same time as entering the gas lighter inspection mode 72, the threshold value TH1 for normal methane gas set in the startup mode 70 is changed to the inspection threshold value TH2. For this reason, the detection signals of the detection timings A3, A4, and A5 of the methane gas using the inspection gas containing CO gas and hydrogen gas are higher than the inspection threshold TH2 after the change, and the detection timing of the methane gas is the same as that of the original methane gas. Even when a check gas including gas and hydrogen gas is used, a gas leak warning for methane gas can be output and operation check for methane gas can be performed.

  FIG. 6 is a graph showing the relationship between the resistance value of the CO detection timing of the gas leak detection element and the resistance value of the methane gas detection timing with respect to the CO gas concentration as the main component of the inspection gas.

  In FIG. 6, the horizontal axis represents the CO concentration, and the vertical axis represents the sensor resistance of the gas detection element. First, the CO gas detection timing resistance 82 of the gas detection element with respect to the CO gas concentration at the CO detection timing is large, for example, 1 MΩ when the CO concentration in normal air is 0 ppm, and when the CO gas concentration increases, the exponential function In particular, the sensor resistance value decreases, for example, the sensor resistance decreases to, for example, 7 kΩ at 150 ppm at which a CO gas gas leak alarm is issued, and further decreases to 1 kΩ or less as the CO gas concentration increases.

  On the other hand, the methane detection timing resistance 84 of the gas detection element with respect to the CO gas concentration at the methane detection timing decreases from the state of about 6 kΩ in the atmospheric methane detection timing resistor 86 to about 5 kΩ with respect to the increase of the CO gas concentration. It can be seen that a change in resistance value (relative change) exceeding about 1 kΩ occurs with respect to the atmospheric methane detection timing resistance 86.

  FIG. 7 is a time chart showing changes in the methane detection timing resistance together with changes in the CO detection timing resistance when the inspection gas collected from the flame of the gas lighter is actually injected in the gas lighter inspection mode.

  In FIG. 7, before the gas injection start 88, as shown in the methane detection timing resistance 90-1, since there is no CO gas or hydrogen gas in the atmosphere, the sensor resistance is about 6 kΩ. Yes. At this time, the methane alarm threshold is set to RTH1 during normal monitoring.

  In this state, as shown in the gas injection start 88, when the inspection gas containing CO gas and hydrogen gas collected from the gas lighter is injected, the methane detection timing resistance 90- is increased from 6 kΩ of the methane detection timing resistance 90-1 so far. After decreasing to 2 kΩ or less as shown in 2, it gradually increases with the divergence of the inspection gas and transitions like a methane detection timing resistance 90-3.

  Here, in the gas lighter inspection mode for injecting the inspection gas, the normal methane alarm threshold value RTH1 is changed to the methane inspection alarm threshold value RTH2 used for inspection, and therefore the methane detection timing after the gas injection start 88 is reached. When the resistance 90-2 is lowered to a methane inspection alarm threshold value RTH2 or less, the inspection of operation is performed by issuing a gas leakage alarm of methane gas at the detection timing of methane gas by injecting inspection gas composed of CO gas and hydrogen gas. it can.

  On the other hand, the CO detection timing resistance 92-1 in the atmosphere before the start of gas injection 88 is 1 MΩ, and after the start of gas injection 88, the resistance value rapidly decreases due to the CO gas contained in the inspection gas. As shown by the detection timing resistance 92-2, the voltage decreases to around 0.5 kΩ.

  For this reason, a CO gas leakage alarm is issued when the CO high concentration threshold value RTH3 is set in advance, and the operation check can be simultaneously performed on the CO gas using the check gas. Of course, since the accumulation time for CO gas leakage is reset to zero at the time of inspection, a CO gas alarm can be immediately issued without accumulation.

  Note that the CO detection timing resistance 92-2 is rapidly restored to the original 1 MΩ CO detection timing resistance 92-3 as CO gas diffuses after being lowered by gas injection.

  Here, in FIGS. 6 and 7, the resistance value of the gas detection element is shown, but actually, as shown in the detection circuit unit 28 of FIG. 2, the transistor with respect to the resistance value Rx of the gas detection element 40. By switching the detection resistors 52 and 54 by 50, the CPU 30 takes in the detection voltage E1 in accordance with the equations (1) and (2).

If there is further required, as shown in the detection signal of FIG. 5 (B), by the inverted detection signal E1 (Vcc-E1), converted to a detection signal which increases in response to the gas concentration And you may take in with an AD converter.

  8 and 9 are flowcharts showing the operation inspection process of the present embodiment for changing the methane alarm threshold value to the inspection threshold value in the gas lighter inspection mode.

  In FIG. 8, when the AC 100V power supply is turned on for the alarm device 10 of the present embodiment, initialization diagnosis processing is executed in step S1, and if normal activation is determined in step S2, the process proceeds to step S3, and FIG. As shown in B), the gas lighter inspection mode 72 is set. In the setting of the gas lighter inspection mode 72, the normal methane threshold value is changed to the inspection threshold value, and the accumulation of CO is released.

  Subsequently, when the methane detection timing corresponding to the methane detection point 78 shown in FIG. 3 is determined in step S4, a methane detection signal is read in step S5. In this gas lighter inspection mode 72, since the inspection gas collected from the flame of the gas lighter is injected into the gas detection unit 16, the methane detection signal read in step S5 is the resistance value of the gas detection element 40. Along with the decrease, for example, the signal increases due to inversion processing of the detection signal. If it is determined in step S6 that the methane detection signal is equal to or greater than the inspection threshold value, the CO gas collected from the flame of the gas lighter in step S7. Even a check gas including hydrogen gas can output a gas leak (methane) alarm and check the operation of the gas leak (methane).

  Subsequently, in step S8, if it is determined that it is the CO detection timing at the CO detection point 80 shown in FIG. 3, the process proceeds to step S9, the CO detection signal is read, and if the CO detection signal is greater than or equal to the threshold value in step S10, In step S11, a CO alarm is issued. At this time, since the accumulation time for CO is zero, the CO alarm is immediately output without accumulation.

  Such an operation process in the gas lighter inspection mode 72 in steps S4 to S11 is repeated until the set time of the gas lighter gas inspection mode elapses in step S12.

  When it is determined in step S12 that the set time has elapsed, the process proceeds to step S13 in FIG. 9, and the normal inspection mode 74 is set. In this mode setting, the methane inspection threshold is returned to the normal threshold.

Subsequently, when the methane detection timing is determined in step S14, a methane detection signal is read in step S15. If the methane detection signal is greater than or equal to a threshold value, that is, exceeds a normal threshold value in step S16, a gas leak (methane) alarm is detected in step S17. Will be issued. However, since the methane detection signal does not exceed the threshold value in the normal inspection mode, the methane gas leak warning in step S17 is skipped.

  Subsequently, when the CO detection timing is determined in step S18, the CO detection signal is read in step S19. If the CO detection signal is equal to or greater than the threshold value in step S20, a CO alarm is issued in step S21.

  At this time, if the inspection gas containing CO gas and hydrogen gas collected from the flame of the gas lighter is injected for the inspection operation of CO, the CO detection signal read in step S19 becomes the threshold value or more in step S20, and step S21. The CO alarm is performed and the operation of the CO gas leak can be confirmed.

Such processes of steps S14 to S21 are repeated until the set time of the normal inspection mode elapses in step S22. If it is determined in step S22 that the set time has elapsed, the process proceeds to step S23, and the normal monitoring mode is set. In the normal monitoring mode, the CO gas accumulation cancellation is reset to return to the original accumulation operation, and then the normal monitoring process is started in step S24.

  FIG. 10 is a time chart showing heater control signals, gas detection element detection signals, and modes in a gas lighter inspection mode according to another embodiment of the present invention.

  In the embodiment of FIG. 10, for each of the detection signals at the methane detection points A2, A3, A4, and A5 in the gas lighter inspection mode 72, for example, changes H1, H2, H3, and H4 with respect to the detection signal 0 are detected. When these changes exceed a predetermined inspection threshold, a gas leak (methane) alarm is output.

Further, in FIG. 10B, changes H1, H2, H3, H4 from the zero level of the detection signals at the methane detection points A2, A3, A4, A5 in the gas lighter inspection mode 72 are detected. The methane detection point A1 in the start mode 70 may be set as an initial value, and a change amount with respect to the initial value A1 may be detected and compared with an inspection threshold value.

FIG. 11 and FIG. 12 are flowcharts showing the operation inspection process of the embodiment in which a methane detection alarm is output from the change amount of the detection signal in the gas lighter inspection mode. In the flowcharts of FIGS. 11 and 12, steps S3 to S7 are unique processes, and the other processes are the same as those in the flowcharts of FIGS.

  That is, in step S3 of FIG. 11, when the gas lighter inspection mode is set, the gas detection element when the methane detection timing is set for the inspection gas containing CO gas and hydrogen gas collected from the gas lighter. A threshold change amount for determining a gas leak (methane) is set based on the change amount of the detection signal from.

  Subsequently, when the methane detection timing is determined in step S4, a methane detection signal is read in step S5, and the amount of change is detected. Subsequently, if the change amount of the methane detection signal is greater than or equal to the threshold change amount in step S6, the process proceeds to step S7, and a gas leak (methane) alarm is output even if the detection signal is due to the injection of inspection gas, and the methane detection timing. It is possible to check the operation at

  The functions of steps S3 to S7 change the functions of the threshold setting unit 66 and the operation inspection unit 68 provided in the inspection processing unit 64 of the CPU 30 in FIG. 2 into a function for determining the change amount of the detection signal at the methane detection timing. This can be achieved.

  That is, in order to realize the processing of steps S3 to S7 in FIG. 11, the threshold value setting unit 66 in FIG. 2 sets the methane detection timing for the inspection gas composed of CO gas and hydrogen gas collected from the flame of the gas lighter. A threshold change amount for determining gas leakage (methane) is set from the change amount of the detection signal from the gas detection element.

Further, the operation check unit 68 sets the threshold change amount set by the threshold setting unit 66 based on the change amount of the detection signal from the gas detection element obtained at the methane detection timing during the setting of the gas lighter check mode in which the check gas is injected. If this is exceeded, a gas leak will be warned.

  In the above embodiment, an example of checking the gas leakage at the methane detection timing using an inspection gas containing CO gas and hydrogen gas collected from the flame of a commercially available gas lighter as the inspection gas is taken as an example. However, an appropriate inspection gas can be used as long as it is a readily available gas containing other CO gas.

  Moreover, although said embodiment took the alarm device provided with the fire detection part as an example, of course, the alarm device only for gas leak may be sufficient.

  Furthermore, although the above-described embodiment is an alarm device using a commercial AC 100 V as a power source, an alarm device using a battery power source may be used.

The present invention includes appropriate modifications that do not impair the object and advantages thereof, and is not limited by the numerical values shown in the above embodiments.

Explanatory drawing which showed embodiment of the alarm device by this invention Circuit block diagram showing the functional configuration and circuit configuration of the alarm device of FIG. Explanatory drawing which showed heater control and detection timing of methane detection and CO detection in this embodiment Time chart showing mode transition at power-on in this embodiment Time chart showing heater control and detection signal in gas lighter inspection mode of this embodiment Graph showing the relationship between CO detection timing resistance and methane detection timing resistance against CO gas concentration Time chart showing changes in methane detection timing resistance with changes in CO detection timing resistance when injecting inspection gas collected from gas lighter flame in gas lighter inspection mode The flowchart which showed the operation check processing of this embodiment which changes a methane warning threshold value in gas lighter check mode. The flowchart which showed the operation inspection process following FIG. Time chart showing heater control and detection signal in gas lighter inspection mode in another embodiment of the present invention The flowchart which showed the operation check processing of embodiment which outputs a methane detection alarm from the amount of change of a detection signal in gas lighter check mode. The flowchart which showed the operation | movement inspection process following FIG.

Explanation of symbols

10: Alarm 12: Housing 14: Fire detection unit 16: Gas detection unit 18: Speaker 20: Fire alarm light 22: Power light 24: CO alarm light 26: Methane alarm light 28: Detection circuit unit 30: CPU
32: Non-volatile memory 34: Display unit 36: Audio output unit 38: Gas sensor 40: Gas detection element 42: Heater 44, 50: Transistor 46, 48: Resistance 52, 54: Detection resistance 56: Gas signal processing unit 58: Heater control Unit 60: Calculation unit 62: Timer 64: Inspection processing unit 66: Threshold setting unit 68: Operation inspection unit 70: Startup mode 72: Methane inspection / CO inspection mode 74: CO inspection mode 76: Normal monitoring mode 78: Methane detection point 80: CO detection point 82, 92-1 to 92-3: CO detection timing resistor 84, 90-1 to 90-3: Methane detection timing resistor 86: Atmospheric methane detection timing resistor 88: Gas injection start

Claims (6)

The first detection condition for detecting the first detection target gas and the second detection condition for detecting the second detection target gas are alternately set at a predetermined time interval in a single semiconductor gas detection element. And a gas alarm device for determining and alarming a gas leak by comparing a detection signal from the gas detection element obtained in the setting state of the first detection condition or the second detection condition with a predetermined threshold value. In
The predetermined threshold for determining the gas leakage of the first detection target gas at the time of setting the inspection mode is determined as a gas leak by the inspection gas not including the first detection target gas but including the second detection target gas. A threshold setting unit for changing to a threshold;
During the setting of the inspection mode in which the inspection gas is injected, when the detection signal from the gas detection element according to the setting of the first detection condition exceeds the inspection threshold, the gas leakage of the first detection target gas An operation check unit that warns
A gas alarm device comprising:
The first detection condition for detecting the first detection target gas and the second detection condition for detecting the second detection target gas are alternately set at a predetermined time interval in a single semiconductor gas detection element. And a gas alarm device for determining and alarming a gas leak by comparing a detection signal from the gas detection element obtained in the setting state of the first detection condition or the second detection condition with a predetermined threshold value. In
When setting the inspection mode, the inspection gas detection signal from the gas detection element at the time of setting the first detection condition to check gas containing the second detection target gas without the first detection target gas A threshold value setting unit for setting a threshold value for determining gas leakage from a change amount from an initial value before injecting a gas to a predetermined threshold change amount;
During the setting of the inspection mode in which the inspection gas is injected, when the change amount from the initial value of the detection signal from the gas detection element due to the setting of the first detection condition exceeds the threshold change amount, An operation check unit that warns of gas leakage of the first detection target gas;
A gas alarm device comprising:
3. The gas alarm device according to claim 1, wherein the first detection target gas is methane gas, the second detection target gas is CO gas, and the inspection gas does not contain methane gas and is CO 2. A gas alarm device characterized by being a combustion product gas collected from a gas lighter flame in which gas and hydrogen gas are mixed.
A first detection condition including a first heater control value for detecting a first detection target gas and a first detection timing in a single semiconductor gas detection element, and a second for detecting a second detection target gas. Detection from the gas detection element obtained by alternately setting the heater control value and the second detection condition including the second detection timing at predetermined time intervals and setting the first detection condition or the second detection condition. In the inspection method of the gas alarm device which judges the gas leak by comparing the signal with each predetermined threshold value and alarms,
When the inspection mode is set, the threshold value for determining the gas leakage of the first detection target gas is a predetermined value that is determined to be gas leakage by the inspection gas that does not include the first detection target gas but includes the second detection target gas. A threshold setting step for changing to an inspection threshold;
During the setting of the inspection mode in which the inspection gas is injected, when the detection signal from the gas detection element according to the setting of the first detection condition exceeds the inspection threshold, the gas leakage of the first detection target gas An operation check step for alarming,
A method for inspecting a gas alarm, comprising:
A first detection condition including a first heater control value for detecting a first detection target gas and a first detection timing in a single semiconductor gas detection element, and a second for detecting a second detection target gas. Detection from the gas detection element obtained by alternately setting the heater control value and the second detection condition including the second detection timing at predetermined time intervals and setting the first detection condition or the second detection condition. In the inspection method of the gas alarm device which judges the gas leak by comparing the signal with each predetermined threshold value and alarms,
When the inspection mode is set, the inspection gas of the detection signal from the gas detection element when the first detection condition is set for the inspection gas including the second detection target gas without including the first detection target gas. A threshold value setting step for setting a threshold value for determining gas leakage from a change amount from an initial value before injecting a gas to a predetermined threshold change amount;
During the setting of the inspection mode in which the inspection gas is injected, when the change amount from the initial value of the detection signal from the gas detection element due to the setting of the first detection condition exceeds the threshold change amount, An operation check step for alarming gas leakage of the first detection target gas;
An inspection method for a gas alarm device, characterized by comprising:
In inspection methods of the gas detector according to claim 4 or 5, wherein the first detection target gas is methane, the second detection target gas is CO gas, further, the inspection gas is methane gas A method for inspecting a gas alarm device, characterized in that it is a combustion product gas collected from a gas lighter flame in which CO gas and hydrogen gas are mixed without being included.

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