JPH0590148U - Combustible gas detector - Google Patents

Abstract

(57) [Summary] [Purpose] The present invention provides a combustible gas detection device capable of appropriately setting a 0-point reference value for generating an alarm and monitoring the combustible gas concentration with high accuracy. [Structure] Means for storing the output of the CO sensor 1 when the burner 5 is not in a combustion state as a 0-point reference value for generating an alarm, and the burner is in a combustion state with reference to the stored sensor output. And a determination means for monitoring a sensor output at the time and performing a predetermined alarm operation when the sensor output becomes equal to or higher than a predetermined output for a predetermined concentration of the combustible gas.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a combustible gas detection device, and more particularly, to a combustible gas detection device that measures a carbon monoxide concentration in exhaust gas to detect an abnormal state and activates a predetermined safety device.

[0002]

[Prior Art]

 2. Description of the Related Art Conventionally, gas combustion devices such as indoor water heaters (FE type) have been known. In such gas combustion devices, a so-called catalytic combustion type detection element is used to detect carbon monoxide and the like in exhaust gas. A combustible gas detection device is provided that measures the combustible gas concentration and activates a prescribed safety device.

For example, in the FE type water heater using an AC100V power source, a CO sensor having a catalytic combustion type detection element is arranged at the exhaust port of the main body, and this CO sensor is included in the exhaust gas. The abnormal state is detected by measuring the concentration of carbon monoxide generated, and the gas supply pipe leading to the burner is shut off by the solenoid valve.

That is, as shown in FIG. 9, the CO sensor 1 includes a temperature compensating comparison element (not shown), a fixed resistance, and a movable resistance, which are not shown in the figure. When the sensing element 2 comes into contact with the exhaust gas, heat is generated according to the carbon monoxide concentration in the exhaust gas, and the resistance value changes so that the equilibrium state of the bridge circuit is changed. It collapses and a predetermined voltage is output as the sensor output Vs. When the sensor output Vs exceeds a predetermined set value Vr, it is determined that the carbon monoxide concentration in the exhaust gas is in a dangerous state, an alarm signal is output, and the gas supply source is cut off. It is designed to prevent poisoning accidents due to carbon monoxide filling the room.

In such a combustible gas detection device, since the predetermined fixed alarm level Vr and the sensor output Vs are compared with each other as described above, the sensor output Vs is based on the alarm level Vr. It is necessary to surely set the 0-point reference value when carbon monoxide is not detected, which is the criterion for determining whether or not the CO sensor 1 has been exceeded. By adjusting the resistance, the bridge circuit described above was adjusted to be in a balanced state, and the 0-point reference value was set.

[0006]

[Problems to be solved by the device]

 However, in the above-described conventional combustible gas detection device, the movable resistance of the CO sensor 1 may deviate from the adjustment position in the factory due to vibration or the like generated during use of the water heater. In this case, the 0-point reference value, which is the reference for determining whether the sensor output Vs exceeds the alarm level Vr, is erroneous when carbon monoxide is not detected, which causes a serious error. Then, the sensor output Vs and the predetermined alarm level Vr are compared with each other, and it is judged that the actual carbon monoxide concentration is at the alarm level Vr, but the detector does not reach the alarm level Vr. , There was a danger that the prescribed safety device would not operate at all.

Further, in the contact-type detection element 2 of the CO sensor 1, the resistance value may change in a state where carbon monoxide is not detected due to aging or the like. In such a case, However, the above-mentioned 0-point reference value went wrong, and the same inconvenience could occur.

The present invention has been made in view of the above points, and it is possible to appropriately set the 0-point reference value for generating an alarm, and to ensure that the combustible gas concentration can be monitored with high accuracy. The purpose is to provide a highly reliable combustible gas detection device.

[0009]

[Means for Solving the Problems]

 In order to achieve the above object, the combustible gas detection device according to the present invention is designed to detect a combustible gas contained in exhaust gas discharged from a gas combustion device having a burner with a catalytic combustion type detection element. In the detection device, storage means for storing the sensor output when the burner is not in a combustion state as a 0-point reference value for generating an alarm, and when the burner is in a combustion state with reference to the stored sensor output. And a determination means for performing a predetermined alarm operation when the sensor output is monitored and the output of the sensor exceeds a predetermined output for a predetermined concentration of combustible gas.

[0010]

[Action]

 According to the present invention, as shown in the principle diagram of FIG. 1, the sensor output when the burner is not in the combustion state is stored in the storage means as the 0-point reference value for generating an alarm, and the stored sensor is stored. The output of the burner is used as a reference to monitor the sensor output when the burner is in a combustion state.When the sensor output exceeds a predetermined output for a given concentration of combustible gas, a predetermined alarm action is performed. is there.

[0011]

【Example】

 Embodiments of the present invention will be described below with reference to the drawings. FIG. 2 shows an embodiment of a gas combustion apparatus having a combustible gas detection device according to the present invention, in which a fan 4 for supplying necessary air to a burner 5 is provided at the lower end of the water heater body 3. The air from the fan 4 and the gas from the gas supply pipe (not shown) are sent to the burner 5 in the main body 3 to burn the gas. Then, in the heat exchanger 6 arranged above the burner 5, the water sent from the water supply pipe (not shown) is boiled to hot water of a predetermined temperature. An exhaust port 7 is provided at the upper end of the main body 3 so that combustion gas containing combustible gas such as carbon monoxide from the burner 5 is exhausted. Further, a catalytic combustion type detection element 2 of a CO sensor 1 having the same structure as the conventional one is arranged at the upper end of the main body 3 and at a position where the combustion gas passes.

Further, as shown in FIG. 3, a CO sensor drive circuit 11 is connected to the CO sensor 1, and the drive circuit 11 is connected to a water heater control circuit 12 including a microcomputer (CPU). It is connected. Further, the water heater control circuit 12 is connected with a flow sensor 13 provided in the water supply pipe, a reset switch 14 for releasing an alarm, an alarm buzzer 15, and a fan drive circuit 16. A burner control circuit 17 and a solenoid valve 18 provided in the gas supply pipe are connected to the burner control circuit 17. In the figure, reference numeral 19 is an AC100V power supply line, 20 is a power supply line, and 21 is a signal line.

In such a combustible gas detection device, as shown in FIG. 4, when the power of the water heater main body 3 is turned on by inserting an outlet into an AC100V power source, the CPU of the water heater control circuit 12 operates Upon activation, power is supplied to the CO sensor drive circuit 11 (step S1), and a timer set for a predetermined time is started (step S2). Then, when the timer measures a predetermined time, it is determined that the bridge circuit of the CO sensor 1 is stable (step S3), the sensor output Vs at that time is read (step S4), and the memory in the water heater control circuit 12 is read. By storing this in the RAM 12a, for example, the 0-point reference value V ₀ for issuing an alarm is set (step S5). As a result, the zero point reference value is set when the burner 5 is not in a burning state and carbon monoxide is not generated.

In this state, the signal from the flow sensor 13 determines whether or not the user has opened the water tap (not shown) of the water heater main body 3 to cause water to flow (step S6), and the water is flowing. When the judgment is made, the burner 5 is ignited (step S7) and the fan 4 is rotated (step S8). As a result, the air from the fan 4 and the gas from the gas supply pipe are combusted in the burner 5, and in the heat exchanger 6 arranged above the burner 5, the water sent from the water supply pipe is supplied. Is to be boiled in hot water at a specified temperature.

After that, when it is determined by the signal from the flow sensor 13 that the user has closed the water tap of the water heater main body 3 (step S9), the burner 5 is extinguished (step S10) and the fan 4 is stopped. (Step S11). When it is determined that the user has not closed the water faucet from the signal from the flow sensor 13 (step S9), the sensor output Vs from the CO sensor 1 is used to monitor the carbon monoxide concentration, and the concentration is higher than a predetermined concentration. An alarm is issued in the abnormal state of, and the burner 5 is extinguished by shutting off the electromagnetic valve 18 provided in the gas supply pipe (step S12).

That is, in step S12, as shown in detail in FIG. 5, the sensor output Vs from the CO sensor 1 is read (step S12a), and the read sensor output Vs and the 0-point reference value are read. takes the difference Vs-V ₀ of to V ₀ (step S12 b), the difference Vs-V _0, predetermined, for example, warning level Vr stored in the RAM of the memory 12a in the water heater control circuit 12 The size is judged by comparing with (step S12c). Then, when the direction of the difference Vs-V ₀ is large, actuates the warning buzzer 15 (step S12d), it is adapted to extinguish the burner 5 by blocking the electromagnetic valve 18 provided in the gas supply pipe ( Step S12e).

After that, when it is determined that the reset switch 14 for releasing the alarm is operated (step S12f), the operation of the alarm buzzer 15 is stopped (step S12g), and the water not boiled up to the predetermined temperature flows. When it is determined that the reset switch 14 has not been operated (step S12f), the alarm buzzer 15 continues to operate. Further, when it is determined that the difference Vs-V ₀ is smaller than the warning level Vr (step S12c), the combustion of the burner 5 is maintained.

In the present embodiment, when the burner 5 burns, the combustion gas comes into contact with the detection element 2 of the CO sensor 1 arranged in the water heater body 3, whereby the carbon monoxide in the exhaust gas is discharged. The concentration is to be monitored.

Therefore, in the present embodiment, due to vibration or the like generated while the water heater body 3 is in use, the movable resistance of the CO sensor 1 deviates from the adjustment position in the factory and the 0-point reference value is deviated, resulting in an error. Even if only the sensor output Vs including is output, the 0-point reference value V _{0 for} issuing an alarm is set when the power of the water heater main body 3 is turned on. A new 0-point reference value V ₀ is set in a state in which the deviation of the 0-point reference value is included. Then, the difference Vs-V ₀ between the sensor output Vs and the new zero point reference value V _0, since adapted to compare the warning level Vr corresponding to dangerous concentrations of carbon monoxide to a predetermined one The carbon oxide concentration can be monitored with high accuracy, and the safety and reliability of the gas combustion device can be significantly improved.

Further, the resistance value of the contact-type detection element 2 of the CO sensor 1 in a state where carbon monoxide is not detected changes due to secular change or the like, and thereafter, the resistance value of the detection element 2 changes. Even if the temperature changes depending on the carbon monoxide concentration, the outlet of the water heater main unit 3 should be regularly plugged in and unplugged, and the power should be turned on periodically to ensure that the above monoxide A new 0-point reference value V ₀ is set in a state that includes aging of the sensing element 2 when carbon is not detected, and is not affected by the aging of the sensing element 2 described above. The carbon monoxide concentration can be monitored with high accuracy.

6 to 8 show another embodiment of the combustible gas detection device according to the present invention, in which the above-mentioned new setting of the 0-point reference value V ₀ is performed by the water heater body 3 described above. This is done at times other than when the power is turned on.

That is, in the case shown in FIG. 6, when the power supply of the water heater main body 3 is turned on, the CPU of the water heater control circuit 12 is activated to supply power to the CO sensor drive circuit 11 (step S1), a timer set for a predetermined time (T minutes) is started (step S2). When it is determined that the timer has counted the predetermined time (step S3), a series of processes from ignition to extinguishing of the burner 5 similar to steps S6 to S12 in FIG. 4 is performed (step S3). Step S4).

When it is determined that the burner 5 is not in the combustion state (in the fire extinguishing state) in the above ignition and fire extinguishing processing (step S4), the timer is started again (step S5), and the burner 5 is extinguished. After checking (step S6), if the timer measures a predetermined time and the sensor output Vs is determined to be stable (step S7), the sensor output Vs at that time (burner 5 in the extinguished state) is read (step S8), By storing this in the memory 12a in the water heater control circuit 12, the 0-point reference value V ₀ for issuing an alarm is set (step S9). If it is determined that the burner 5 is ignited after the start of the timer (step S5) (step S6), it is determined whether or not the water is stopped again in the ignition extinguishing process (step S4), and the subsequent extinguishing process is performed. It is supposed to be done.

When it is determined that water has flowed by the signal from the flow sensor 13 after the setting of the 0-point reference value V ₀ and before the timer time T has elapsed in step S3 (step S10). The ignition extinguishing process (step S4) is performed after the ignition.

Therefore, in the present embodiment, the sensor output Vs when the burner 5 is not in the combustion state is set as a new 0-point reference value V ₀ at every predetermined time T minutes, and the value V ₀ is used as the basis. As described above, the sensor output Vs corresponding to the carbon monoxide concentration when the burner 5 is in the combustion state is monitored, so that it may be affected by the above-mentioned vibration and aging. The carbon monoxide concentration can be monitored with high accuracy.

Further, in the case shown in FIG. 7, when the power of the water heater main body 3 is turned on, the CPU of the water heater control circuit 12 is activated to supply power to the CO sensor drive circuit 11 (step S1), and thereafter, a series of processes from ignition to extinction of the burner 5 similar to steps S6 to S10 and step S12 of FIG. 4 is performed (step S2).

In the case of the present embodiment, when the burner 5 extinguishes, the post fan operation is performed to cool the water heater main body 3 and the timer for the post fan starts. (Step S3) After confirming the extinguishing of the burner 5 again (Step S4), if the timer outputs a predetermined time and the post fan time elapses and it is determined that the sensor output Vs is stable (Step S5), The sensor output Vs at that time (the burner 5 is in a fire extinguishing state) is read (step S6) and is stored in the memory 12a in the water heater control circuit 12, so that the 0-point reference value V ₀ is set (step S7), and then the fan 4 is stopped (step S8). When it is determined that the burner 5 is ignited after the timer is started (step S3) (step S4), it is determined whether the water is stopped again in the ignition extinguishing process (step S2), and the subsequent extinguishing process is performed. It has become so.

Therefore, also in this embodiment, a new 0-point reference value V ₀ is set during the operation of the post fan after the burner 5 is extinguished, and the sensor output Vs is monitored based on this value V _0. Therefore, the carbon monoxide concentration can be monitored with high accuracy without being affected by the above-mentioned vibration and aging.

In the case of the present embodiment, the setting operation of the 0-point reference value V ₀ described above is not performed in the first use after the water heater is installed, but a predetermined 0-point reference value is preset at the factory shipment stage. Is set, so there is no problem.

Further, in the case shown in FIG. 8, the setting operation of the 0-point reference value V ₀ described above is performed after the post fan operation described in FIG. 7 is completed.

That is, when the power of the water heater main body 3 is turned on, the CPU of the water heater control circuit 12 is activated to supply power to the CO sensor drive circuit 11 (step S1), and then step S6 of FIG. From step S10 to step S12, a series of processes from ignition to extinction of the burner 5 is performed (step S2). After that, a timer for the post fan is started (step S3), and when the timer measures a predetermined time and determines that the post fan time has elapsed (step S4), the fan 4 is stopped (step S4). S5).

After that, the timer is started again (step S6), and after confirming the extinction of the burner 5 again (step S7), when the timer measures a predetermined time and the sensor output Vs is determined to be stable (step S8). ), The sensor output Vs at that time (the burner 5 is in the fire extinguishing state) is read (step S9), and the sensor output Vs is stored in the memory 12a in the water heater control circuit 12 to generate a warning 0-point reference. The value V ₀ is set (step S10). If it is determined that the burner 5 is ignited after the timer is started (step S6) (step S7), it is determined whether the water is stopped again in the ignition extinguishing process (step S2), and the subsequent extinguishing process is performed. It is like this.

Therefore, also in this embodiment, a new 0-point reference value V ₀ is set after the post-fan operation after the burner 5 is extinguished, and the sensor output Vs is monitored based on this value V _0. Therefore, it is possible to monitor the carbon monoxide concentration with high accuracy without being affected by the above-mentioned vibration and secular change.

In the above embodiment, the CO sensor 1 is composed of the bridge circuit composed of the catalytic combustion type detection element 2, the temperature compensating comparison element, the fixed resistance and the movable resistance as in the conventional case. The resistance may be replaced by a fixed resistance, and may be configured by a contact combustion type detection element 2, a temperature compensation comparison element, and a bridge circuit composed of two fixed resistances. This makes it possible to prevent vibration during use of the water heater. It is possible to prevent the resulting displacement of the movable resistance from the adjustment position in the factory, which is more preferable.

Further, in the above embodiment, the difference Vs−V ₀ between the sensor output Vs and the new zero point reference value V ₀ is compared with the alarm level Vr corresponding to a predetermined dangerous concentration of carbon monoxide. However, according to the setting of the new 0-point reference value V ₀ , the set value V r as an absolute alarm level predetermined at the factory stage or the like is set without taking the difference Vs−V _0. Even if it is variable, the same effect can be obtained.

Further, in the above embodiment, the concentration of carbon monoxide in the exhaust gas is detected, but any combustible gas can be detected.

[0037]

[Effect of the device]

 As described above, the combustible gas detection device according to the present invention stores the sensor output when the burner is not in the combustion state as a 0-point reference value for generating an alarm, and the stored sensor output. As a reference, it is provided with a judging means for monitoring the sensor output when the burner is in a combustion state and performing a predetermined alarm operation when the sensor output becomes higher than a predetermined output for a predetermined concentration of combustible gas. Therefore, the 0-point reference value for issuing an alarm can be set as appropriate, which prevents deterioration of the sensor output performance due to vibration during use of the gas combustion device, aging of the sensing element, etc. The combustible gas concentration can be monitored with high accuracy, and safety and reliability can be extremely enhanced.

[Brief description of drawings]

FIG. 1 is a principle view of a combustible gas detection device according to the present invention.

FIG. 2 is a schematic configuration diagram of a gas combustion device having a combustible gas detection device according to the present invention.

FIG. 3 is a block diagram showing a combustible gas detection device provided in the gas combustion device.

FIG. 4 is a flow chart for explaining the operation of an embodiment of the combustible gas detection device.

5 is a flowchart illustrating an alarm process in FIG.

FIG. 6 is a flowchart for explaining the operation of another embodiment of the combustible gas detection device.

FIG. 7 is a flowchart for explaining the operation of still another embodiment of the combustible gas detection device.

FIG. 8 is a flowchart for explaining the operation of still another embodiment of the combustible gas detection device.

FIG. 9 is a schematic configuration diagram of a CO sensor.

[Explanation of symbols]

 1 CO sensor 2 detection element 3 water heater main body 4 fan 5 burner 12 water heater control circuit (CPU)

 ─────────────────────────────────────────────────── ─── Continued Front Page (72) Masato Kondo 3-4 Fukamidai, Yamato City, Kanagawa Prefecture (72) Toshiaki Tabei 2-25-24 Motomachi, Urawa City, Saitama Prefecture

Claims (3)

[Scope of utility model registration request] 1. A combustible gas detection device in which a combustible gas contained in the exhaust gas discharged from a gas combustion device having a burner is detected by a catalytic combustion type detection element when the burner is not in a combustion state. Storage means for storing the sensor output of 0 as a 0-point reference value for generating an alarm,
The sensor output when the burner is in a combustion state is monitored based on the stored sensor output, and a predetermined alarm operation is determined when the sensor output exceeds a predetermined output for a predetermined concentration of combustible gas. A combustible gas detection device comprising: 2. When the power source of the gas combustion device is turned on, 0
The combustible gas detection device according to claim 1, wherein a sensor output as a point reference value is stored in the storage means. 3. The combustible gas detection device according to claim 1, wherein a sensor output as a 0-point reference value is stored in the storage means in response to extinction of the burner.