JPH11337173A - Gas water heater - Google Patents

Abstract

PROBLEM TO BE SOLVED: To detect the incomplete combustion of a gas burner more accurately. SOLUTION: This water heater is provided with a relatively high voltage output of thermocouple 3 which detects the combustion state of a gas burner 1, and a relatively low voltage output of heat exchanger 4 which detects the inside temperature of a heat exchanger 2. The output of both thermocouples 3 and 4 is inputted separately into filter circuits 21 and 22 so as to remove higher harmonic components. An operating part 24 seeks the difference being obtained by subtracting the output voltage of the filter circuit 22 from the output voltage of the filter circuit 21. A combustion state judger 24 judges that the gas burner 1 is in incomplete combustion when the output of the operating part 23 becomes smaller than the specified threshold, and shuts off the safety valve 15 supplying the gas burner with fuel gas.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a relatively small gas water heater generally installed indoors.

[0002]

2. Description of the Related Art Generally, a gas water heater of this kind is provided with a gas burner for burning fuel gas and a flow between a water inlet and a water outlet provided in a water heater main body which is a housing of the gas water heater. A heat exchanger provided on the road for heating water introduced from a water supply port by a gas burner and discharging the water from a tap hole; By the way, in the gas water heater, when incomplete combustion occurs in the gas burner, soot is generated and becomes dirty, and problems such as a decrease in combustion efficiency occur.In particular, incomplete combustion occurs in a gas water heater installed indoors. Since carbon monoxide is generated and is dangerous, it is necessary to provide a safety device for detecting incomplete combustion and stopping combustion of the gas burner.

Therefore, in a conventional gas water heater, as shown in FIG. 3, a thermocouple 3 for detecting the combustion state of the gas burner 1 and a thermocouple 4 for detecting the internal temperature of the heat exchanger 2 are provided. Are connected with polarities (hereinafter, referred to as anti-series) canceling each other out of the thermocouples 3 and 4, and the voltage between both ends of the series circuit of the thermocouples 3 and 4 is compared with a reference voltage. Accordingly, it has been considered to detect the occurrence of incomplete combustion. The internal temperature of the heat exchanger 2 is detected by inserting the temperature detector of the thermocouple 4 into the small window 2a provided in the heat exchanger 2.

As the thermocouple 3 corresponding to the gas burner 1, a thermocouple which outputs a relatively high voltage (for example, about 20 mV) is used, and the thermocouple 4 corresponding to the heat exchanger 2 has a relatively low voltage (for example, Output of about 4 mV) is used. If the two thermocouples 3 and 4 are connected in anti-series as described above, the voltage at both ends of the series circuit of the two thermocouples 3 and 4 during incomplete combustion is lower than that during normal combustion.
By utilizing this, the incomplete combustion state can be detected. The voltage across the series circuit of the thermocouples 3 and 4 is smoothed and compared with the reference voltage by the comparator 5. When the voltage across the series circuit of the thermocouples 3 and 4 falls below the reference voltage, the fuel gas is supplied to the gas burner 1. The safety valve 6 composed of an electromagnetic valve provided in the flow path for supplying the gas is closed to stop the combustion of the gas burner 1.

[0005]

As shown in FIG. 4, the output voltage of each of the thermocouples 3 and 4 includes a high-frequency component due to, for example, fluctuation of a flame. The voltage across the circuit also includes many high frequency components. Then, the voltage between both ends of the series circuit of both thermocouples 3 and 4 is passed through a filter circuit to smooth out high-frequency components, and then compared with a reference voltage by a comparator 5.

However, for example, the output voltage of thermocouple 3 is 20 ± 3 mV, and the output voltage of thermocouple 4 is 4 mV ± 2 m
If it is V, the voltage between both ends of the series circuit of both thermocouples 3 and 4 is 16 ± 5 mV and has a fluctuation component of ± 5 mV, and the fluctuation component is the original fluctuation of each thermocouple 3 and 4. Larger than the component. In other words, even if the voltage across the series circuit of the thermocouples 3 and 4 is smoothed, a large amount of ripple components remains even if the voltage between both ends of the thermocouple is smoothed. Must be set low. However, when the reference voltage is set low, normal combustion may be determined due to some noise, which causes a problem in noise resistance. Also, if a low reference voltage is set so that the response to the ripple component has a margin,
There is also a problem that detection of incomplete combustion is easily delayed.

In order to solve this kind of problem, it is conceivable to increase the capability of removing a ripple component in a filter circuit for smoothing the voltage across the series circuit of the thermocouples 3 and 4. A problem arises in that the size of the components is increased and the time constant of the smoothing filter circuit is increased, resulting in poor response.

Further, the output voltage of the filter circuit rises with the passage of time after the ignition of the gas burner 1 and is thereafter kept substantially constant. Therefore, the lower limit value of the output voltage of the filter circuit after the ignition of the gas burner 1 is equal to the reference voltage. During the time exceeding the limit, the judgment of incomplete combustion must not be made. However, since the output voltage of the filter circuit contains many ripple components as described above, the gas burner 1
It is necessary to take a relatively long time to prevent the determination of incomplete combustion from the ignition of the gas burner, and the incomplete combustion state immediately after the ignition of the gas burner 1 cannot be detected.

The present invention has been made in view of the above circumstances, and has as its object to reduce the occurrence of erroneous determination of incomplete combustion and to detect incomplete combustion with good responsiveness. It is to provide a gas water heater.

[0010]

According to a first aspect of the present invention, there is provided a gas burner for burning fuel gas, and water passing through a flow path between a water supply port for introducing water and a hot water outlet for discharging hot water. , A first thermocouple disposed near the gas burner for generating a voltage corresponding to the combustion state of the gas burner, and a second thermocouple for generating a voltage corresponding to the temperature of the heat exchanger A pair, a pair of filter means for removing high-frequency components of output voltages of the first and second thermocouples, an operation unit for calculating a difference between outputs of the two filter means, and the difference obtained by the operation unit is defined as A combustion state determination unit that determines that the gas burner is in an incomplete combustion state when the threshold value is equal to or less than a threshold value, and combustion stop means that stops combustion of the gas burner when the combustion state determination unit determines that the gas burner is in an incomplete combustion state. Than it is.

According to a second aspect of the present invention, in the first aspect of the present invention, the combustion stopping means is a safety valve comprising an electromagnetic valve inserted into a flow path of fuel gas supplied to the gas burner;
A valve drive unit for closing the safety valve when the incomplete combustion state is detected by the combustion state determination unit.

According to a third aspect of the present invention, there is provided the gas burner according to the first or second aspect, wherein a time period in which the difference exceeds the threshold from the ignition of the gas burner in a normal state is set as a dead zone time, And a dead zone processing unit that prohibits the combustion state determination unit from judging the incomplete combustion state during the dead zone time limited by the time unit from the ignition of the engine.

According to a fourth aspect of the present invention, in the first to third aspects of the present invention, when the gas burner is ignited, the combustion state determining section determines that the combustion state is incomplete, and the combustion stopping means stops the combustion of the gas burner. Prohibition means for prohibiting the ignition of the gas burner after the specified number of times has been repeated continuously, and prohibition of combustion by manual operation different from the time of hot water supply in a state where the ignition of the gas burner is prohibited by the combustion prohibition means. Reset means for resetting the means to cancel the inhibition of ignition of the gas burner.

According to a fifth aspect of the present invention, in the fourth aspect of the present invention, there is provided a water heater body accommodating at least the gas burner and the heat exchanger, and the resetting means is provided with a reset switch provided inside the water heater body. Consisting of

According to a sixth aspect of the present invention, in the invention of the fourth aspect, at least the arithmetic unit and the combustion state determination unit use a battery as a power source, and the reset unit includes a power reset circuit for resetting the combustion prohibiting unit when the battery is replaced. It becomes.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS (Embodiment 1) As shown in FIG. 1, a gas burner 1 and a heat exchanger 2 are housed in a water heater main body 11 which is a housing of a gas water heater. Boiler body 11
The heat exchanger 2 is provided on a flow path between the water supply port 12 and the tap hole 13 provided in the water supply port, and the water introduced into the heat exchanger 2 through the water supply port 12 is heated by the gas burner 1 and the hot water is discharged from the tap port 13. Is configured. On the flow path for supplying the fuel gas to the gas burner 1, a device plug 14 for manually adjusting the flow rate is provided.
In addition, a safety valve 15 composed of a solenoid valve is also inserted.
As the igniter 16 of the gas burner 1, one that repeatedly generates a spark until the gas burner 1 ignites is used. Further, a water flow valve 17 composed of an electromagnetic valve is provided between the water supply port 12 and the heat exchanger 2, and by operating an ignition switch 18 provided on the water heater body 11, the safety valve 15 is opened and the ignition is started. The vessel 16 operates and the water flow valve 17 is opened. That is, the ignition switch 1
The operation of 8 starts the ignition and tapping of the gas burner 1. When the ignition switch 18 is operated again, the hot water is stopped and the gas burner 1 is extinguished. The adjustment of the flow rate of the fuel gas is adjusted by manual operation of the instrument stopper 14,
The amount of hot water is adjusted by a valve (not shown) provided between the water supply port 12 and the hot water port 13 so as to interlock with the appliance plug 14. That is, the flow rate of the fuel gas is adjusted according to the amount of hot water.

In the present embodiment, in order to detect incomplete combustion of the gas burner 1, a thermocouple 3 which is disposed near the gas burner 1 and generates a voltage corresponding to the ignition of the gas burner 1 is provided, similarly to the conventional configuration. Window hole 2a provided in heat exchanger 2 (a window hole is provided in a box housing heat exchanger 2)
And a thermocouple 4 in which a temperature detection unit is inserted. However,
In the conventional configuration, both thermocouples 3 and 4 are connected in anti-series, and the voltage between both ends of the series circuit is smoothed. In the present embodiment, the output voltages of the thermocouples 3 and 4 are respectively filtered by a filter circuit ( The high-frequency components are input to filter means 21 and 22 to remove high-frequency components separately. Both filter circuits 2
The output voltages 1 and 22 are input to the arithmetic unit 23, and the output of the filter circuit 22 corresponding to the thermocouple 4 is subtracted from the output of the filter circuit 21 corresponding to the output of the thermocouple 3 to obtain a difference. This difference is compared with the reference voltage (specified threshold value) in the combustion state determination unit 24, and when the difference becomes equal to or less than the reference voltage, it is determined that the combustion state is incomplete. When the incomplete combustion is detected by the combustion state determination unit 24 in this way, the safety valve 15 is closed through the valve drive unit 25.

The difference output from the arithmetic unit 23 increases gradually after the gas burner 1 is ignited, and is maintained at a substantially constant value after a predetermined time has elapsed. That is, the difference output from the arithmetic unit 23 is equal to or lower than the reference voltage immediately after the ignition of the gas burner 1, and it is not possible to determine whether or not the combustion is incomplete during this time. In view of this, a period of time that exceeds the reference voltage from ignition during normal combustion of the gas burner 1 is set as a dead zone time, and the output of the combustion state determination unit 24 is invalidated during the dead zone period.
That is, a time limiter 26 that limits the dead zone time from the ignition of the gas burner 1, and a dead pair processing unit 27 that disables the output of the combustion state determination unit 24 during the dead zone time limited by the time limiter 26.
Are provided.

With this configuration, the determination of incomplete combustion is not performed during the dead zone time. However, in the present embodiment, since the output voltages of the thermocouples 3 and 4 are separately passed through the filter circuits 21 and 22 to remove the high-frequency component, the thermocouples 3 and 4 are connected in reverse series as in the conventional configuration. Compared with the case where the high frequency component is removed from the voltage between both ends of the series circuit, the ripple component after removing the high frequency component in each of the filter circuits 21 and 22 is reduced, and each of the filter circuits 21 and 22 is removed.
The ripple component included in the difference between the output voltages of the thermocouples 22 is much smaller than the case where the voltage across the series circuit of the thermocouples 3 and 4 is smoothed. As a result, it is possible to remove most of the above-described difference ripple components while using small components for the filter circuits 21 and 22. As described above, since the ripple used for the determination of incomplete combustion hardly includes the ripple component, the dead zone time can be made shorter than in the conventional configuration. If the reference voltage is set the same as in the conventional configuration, the period during which incomplete combustion cannot be detected from ignition of the gas burner 1 can be made shorter than in the conventional configuration. For example, as shown in FIG. 2, in the conventional configuration, incomplete combustion cannot be determined until the average value of the voltage between both ends of the series circuit of the thermocouples 3 and 4 reaches the voltage V1. Then, the determination of incomplete combustion can be started when the difference reaches the voltage V2. In other words, the dead zone time T1 of about 1 minute is required in the conventional configuration, but in the present embodiment, the dead time T2 can be reduced to 20 seconds or less.

The arithmetic unit 23 and the combustion state determination unit 2 described above.
4. The time limit unit 26 and the dead zone processing unit 27 are configured using a microcomputer (abbreviated as a microcomputer).
The filter circuits 21 and 22, the valve drive unit 25, and the microcomputer are mounted on the electric board 20 and arranged in the water heater main body 11. Here, the power source of the circuit arranged in the water heater main body 11 is a battery such as a dry battery, and is replaceable. Further, a reset switch 28 as a reset unit is mounted on the electrical component board 20. The reset switch 28 is manually operated in the following cases.

That is, the safety valve 1 is determined to be incomplete combustion.
Although there are various causes for closing 5, if the room is not sufficiently ventilated and lacks oxygen or malfunctions, the gas burner 1 becomes dirty and the inflow of primary air decreases or the crater becomes clogged. Is the main cause. In the former case, there is no problem in reusing if sufficient ventilation is provided, but in the latter case, it can be reused only after an appropriate treatment such as cleaning is performed.

In consideration of the former cause, even if incomplete combustion is detected by the above-described operation and the safety valve 15 is closed, if the operation of igniting the gas burner 1 is performed, the gas burner 1 can be re-ignited. It is configured to be able to. However, if incomplete combustion is detected due to the latter cause, the cause of incomplete combustion is not removed and it is dangerous. In such a case, a prescribed number of times (for example, three times) Only reignition operation is enabled. That is, when the operation of igniting the gas burner 1 and closing the safety valve 15 by the detection of incomplete combustion is repeated three times in succession, the safety valve 15 is kept closed even if the operation of igniting the gas burner 1 is performed next time. Thus, the gas burner 1 is not ignited. This processing is performed by a combustion prohibition section (combustion prohibition means) 29 provided in the microcomputer.

However, when the combustion prohibiting section 29 operates and the gas burner 1 cannot be re-ignited,
Since work requiring specialized knowledge such as cleaning and repair is required, a contractor is required to perform cleaning or repair. Here, since the trader opens the water heater main body 11, the reset switch 28 can be operated after cleaning or repair is completed, and the gas water heater can be used again.

The scope of application of the technical idea of the present invention is not limited to the gas water heater described above. For example, a curan (not shown) provided with a flow rate sensor and connected to the tap hole 13 may be used. When the water is opened and the water flows between the water supply port 12 and the tap hole 13, the igniter 16 can be used in a gas water heater configured to operate.

When a battery as a power supply is replaced instead of providing the reset switch 28, a power supply reset circuit built in the microcomputer operates and the reset switch 2
8 may be configured to perform the same reset processing.

[0026]

According to the first aspect of the present invention, the gas burner that burns fuel gas and the water that is inserted into and passed through a flow path between a water supply port into which water is introduced and a hot water outlet through which hot water is discharged are heated by the gas burner. And a first heat exchanger which is arranged near the gas burner and generates a voltage corresponding to the combustion state of the gas burner.
Thermocouple, a second thermocouple for generating a voltage corresponding to the temperature of the heat exchanger, a pair of filter means for removing high-frequency components of output voltages of the first and second thermocouples, respectively, and both filters A calculating unit for calculating a difference between the outputs of the means, a combustion state determining unit for determining that the gas burner is in an incomplete combustion state when the difference obtained by the calculating unit is equal to or less than a predetermined threshold value; A combustion stopping means for stopping combustion of the gas burner when it is determined to be in a combustion state, a first thermocouple for generating a voltage corresponding to the combustion state of the gas burner, and a second thermocouple for detecting a temperature of the heat exchanger. 2
After the high-frequency component is removed by passing the output of each of the thermocouples through the filter means separately and the difference is obtained by the calculation unit, the high-frequency fluctuation component is not included in the difference, and the high-frequency fluctuation component is incomplete with little noise. The presence or absence of combustion can be accurately determined. Further, since the filter means is provided for each thermocouple, each filter means can be constituted by a small element having a low withstand voltage, and the time constant of the filter means can be reduced.

According to a second aspect of the present invention, in the first aspect of the present invention, the combustion stopping means is a safety valve comprising a solenoid valve inserted into a flow path of fuel gas supplied to the gas burner;
A valve drive unit that closes the safety valve when the incomplete combustion state is detected by the combustion state determination unit,
When the incomplete combustion is detected, the safety valve is closed to stop the supply of the fuel gas. Therefore, an accident due to the incomplete combustion can be prevented.

According to a third aspect of the present invention, there is provided the gas burner according to the first or second aspect of the present invention, wherein a time period in which the difference exceeds the threshold from the ignition of the gas burner in a normal state is set as a dead zone time, A dead zone processing unit that prohibits the combustion state determination unit from judging the incomplete combustion state in the dead zone time period limited by the time period unit from the ignition of the gas burner, and provides a fixed dead zone time period from the ignition of the gas burner. Accordingly, it is possible to prevent a malfunction during a period when the output of the filter means is unstable, and since the high-frequency fluctuation component is small as described above, the difference output from the calculation unit is relatively short after ignition of the gas burner. Thus, the incomplete combustion can be detected, and the threshold value can be reduced to set the dead zone time short. That is, the period during which detection of incomplete combustion is prohibited is shortened.

According to a fourth aspect of the present invention, in the first to third aspects of the present invention, when the gas burner is ignited, the combustion state determining unit determines that the combustion state is incomplete, and the combustion stop means stops the combustion of the gas burner. Prohibition means for prohibiting the ignition of the gas burner after the specified number of times has been repeated continuously, and prohibition of combustion by manual operation different from the time of hot water supply in a state where the ignition of the gas burner is prohibited by the combustion prohibition means. Reset means for resetting the means to cancel the prohibition of ignition of the gas burner.Also, even if incomplete combustion is detected, re-ignition of the gas burner is permitted a specified number of times, so that incomplete operation due to malfunction or insufficient ventilation In case of combustion, re-ignition is possible after the cause is removed.In case of incomplete combustion due to cause requiring cleaning or repair, after the specified number of times, It is to enhance the safety prohibits the re-ignition. Also, if the gas burner no longer ignites, the user will be informed that cleaning or repair is required.

According to a fifth aspect of the present invention, in the fourth aspect of the present invention, there is provided a water heater body accommodating at least the gas burner and the heat exchanger, and the reset means is provided with a reset switch provided inside the water heater body. In this configuration, resetting cannot be performed unless the water heater main body is opened, so that the user is prevented from inadvertently performing a resetting operation without performing cleaning or repair, and safety is further improved. .

According to a sixth aspect of the present invention, in the fourth aspect of the present invention, at least the arithmetic unit and the combustion state determining unit use a battery as a power source, and the reset unit includes a power reset circuit for resetting the combustion prohibiting unit when the battery is replaced. Since the reset is performed with the replacement of the battery, careless reset can be prevented.

[Brief description of the drawings]

FIG. 1A is a schematic configuration diagram showing an embodiment of the present invention,
(B) is a block circuit diagram of the same.

FIG. 2 is an operation explanatory view of the above.

FIG. 3 is a schematic configuration diagram showing a conventional example.

FIG. 4 is an operation explanatory view of the above.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Gas burner 2 Heat exchanger 3 Thermocouple 4 Thermocouple 11 Water heater main body 12 Water supply port 13 Outlet 15 Safety valve 21 Filter circuit 22 Filter circuit 23 Operation part 24 Combustion state determination part 25 Valve drive part 26 Time limit part 27 Dead zone processing part 28 Reset switch 29 Combustion prohibition section

Continuation of the front page (72) Inventor Mitsuo Sawada 1-15-152, Minami-shioka, Minato-ku, Osaka-shi Inside Harman Co., Ltd. (72) Inventor Takahiko Hyodo 1-1-52, Oka, Minami-shi, Minato-ku, Osaka-shi Herman Co., Ltd.

Claims (6)

[Claims] 1. A gas burner for burning fuel gas, a heat exchanger inserted in a flow path between a water inlet for introducing water and a hot water outlet for discharging hot water and heating the passing water by the gas burner, and a gas burner. , A second thermocouple that generates a voltage according to the temperature of the heat exchanger, a first thermocouple that generates a voltage according to the combustion state of the gas burner, and a first thermocouple that generates a voltage according to the temperature of the heat exchanger.
And a pair of filter means for removing high-frequency components of the output voltage of the second thermocouple, a calculation unit for calculating the difference between the outputs of the two filter means, and when the difference obtained by the calculation unit is equal to or less than a prescribed threshold value. A gas hot water comprising: a combustion state determination unit that determines that a gas burner is in an incomplete combustion state; and combustion stopping means that stops combustion of the gas burner when the combustion state determination unit determines that the gas burner is in an incomplete combustion state. Boiler. 2. The combustion stopping means includes: a safety valve including an electromagnetic valve inserted into a flow path of a fuel gas supplied to the gas burner; and a safety valve when an incomplete combustion state is detected by the combustion state determination unit. 2. The gas water heater according to claim 1, further comprising a valve drive unit for closing. 3. A time period section in which a certain time period from the ignition of the gas burner to the difference exceeding the threshold value is timed as a dead zone time in a normal state, and a combustion state is provided in the dead zone time timed by the time section from the ignition of the gas burner. 3. The gas water heater according to claim 1, further comprising a dead zone processing unit that prohibits the determination unit from determining the incomplete combustion state. 4. When the gas burner is ignited, the combustion state judging section judges that the combustion state is incomplete, and the combustion stop means stops the combustion of the gas burner repeatedly a predetermined number of times. Combustion inhibiting means for inhibiting ignition of the gas burner; resetting means for resetting the combustion inhibiting means by a manual operation different from that during hot water supply in a state in which ignition of the gas burner is inhibited by the combustion inhibiting means to cancel inhibition of ignition of the gas burner; The gas water heater according to any one of claims 1 to 3, further comprising: 5. The water heater according to claim 4, further comprising a water heater main body accommodating at least said gas burner and said heat exchanger, wherein said reset means comprises a reset switch provided inside said water heater main body. Gas water heater. 6. The gas according to claim 4, wherein at least the calculation unit and the combustion state determination unit use a battery as a power supply, and the reset unit includes a power supply reset circuit for resetting the combustion prohibition unit when replacing the battery. Water heater.