JPH09229355A - Combustion control circuit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To decrease a maximum load current in a combustion control circuit using as a power source a power source circuit for converting an alternating current from a battery or a commercial power source into a direct current. SOLUTION: A combustion control circuit comprises a valve opening circuit 23 for forcedly opening a safety valve 14 under an electromagnetic force, a holding circuit 24 for opening and holding the safety valve 14, an ignition circuit 25 and a flame rod circuit 26. During an ignition operation, the valve opening circuit 23 is operated for a short time, and the holding circuit 24 and the ignition circuit 25 are operated for a prescribed ignition time. Then, after the operation of the valve opening circuit 23 is completed, the flame rod circuit 26 is operated.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a combustion control circuit which is applied to a combustor such as a water heater and which uses a power source circuit for converting alternating current from a battery or a commercial power source into direct current.

[0002]

2. Description of the Related Art In a combustor, as a safety measure in case of misfire,
An electromagnetic safety valve was opened in the fuel supply path to the burner, and the electromagnetic safety valve was forcibly opened during ignition operation.After that, while the ignition of the burner was detected by the thermocouple or frame rod, the electromagnetic safety valve was opened. It is adsorbed and held on and the release of raw gas is prevented by closing the electromagnetic safety valve at the time of misfire.

Here, as a method of forcibly opening the electromagnetic safety valve, there are a mechanical method in which the operating force of an operator is used to open the valve, and a large current is applied to the electromagnet of the electromagnetic safety valve to open the valve by electromagnetic force. There is an electric system that does.

When the electric system is adopted, the combustion control circuit includes an ignition circuit for igniting the burner, a valve opening circuit for forcibly opening the electromagnetic safety valve, and a holding circuit for adsorbing and holding the electromagnetic safety valve in an open state. An ignition detection circuit that detects the ignition of the burner is provided.When the ignition operation is performed, the ignition circuit is operated for a certain period of time, and at the beginning of the ignition operation, the valve opening circuit is operated for a short time to forcibly open the electromagnetic safety valve and the ignition detection circuit. The electromagnetic safety valve is held open by the operation of the holding circuit until the electromagnetic safety valve is adsorbed and held in the open state by the signal from.

In this case, if the ignition detection circuit uses a thermocouple, it takes time until a predetermined electromotive force is generated from the thermocouple. Therefore, until the preheating time elapses, even after the operation of the ignition circuit is completed. The electromagnetic safety valve must be held open in the holding circuit, and if the burner is not ignited during operation of the ignition circuit, raw gas will be released.

On the other hand, if the ignition detection circuit is composed of a frame rod circuit that detects the ignition of the burner by using a frame rod, the ignition of the burner can be immediately detected and the electromagnetic safety valve can be adsorbed and held in the open state. The operation of the holding circuit can be terminated at the same time as the ignition circuit, and the release of raw gas due to an ignition mistake can be reliably prevented.

[0007]

By the way, as shown in FIG. 5, the utilization factor of a manganese dry battery generally used as a power supply battery for a combustion control circuit changes depending on the load current. The utilization rate varies depending on individual batteries. The line a in FIG. 5 shows the characteristics of the battery with the maximum utilization rate, and the line b shows the characteristics of the battery with the minimum utilization rate.
It can be seen that if the current exceeds 0 mA, the utilization factor, and hence the battery life, will vary greatly.

As described above, when the valve opening circuit for forcibly opening the electromagnetic safety valve by the electromagnetic force and the frame rod circuit are provided,
In combination with the load current of the ignition circuit, a large load current will flow at the beginning of the ignition operation, and the battery may be exhausted before the designated replacement period of the battery, which may be inconvenient for the user.

Further, when a power supply circuit for converting alternating current from a commercial power supply into direct current is used as a power supply for a combustion control circuit, components such as a transformer and a silicon bridge which compose the power supply circuit can handle a large load current at the beginning of ignition operation. Therefore, it is necessary to use large parts with large ratings, which leads to increase in size and cost of the equipment.

In view of the above points, the present invention has an object to reduce the load current at the beginning of the ignition operation so as to prevent the above problems.

[0011]

Means for Solving the Problems In order to solve the above problems,
The present invention relates to a combustion control circuit using a battery or a power supply circuit for converting alternating current from a commercial power supply to direct current as a power source, and an ignition circuit for igniting a burner and an electromagnetic safety valve provided in a fuel supply path to the burner. A valve opening circuit that forcibly opens the valve with electromagnetic force,
Equipped with a holding circuit that holds the electromagnetic safety valve in the open state by suction, and a frame rod circuit that detects ignition of the burner using the frame rod and that holds the electromagnetic safety valve in the open state while the burner is igniting. During the ignition operation, the valve opening circuit is operated for the first set time, and the ignition circuit and the holding circuit are operated for the second set time set longer than the first set time, and the operation of the valve opening circuit is completed. It is characterized by starting the operation of the frame rod circuit at times.

By shifting the operation start timing of the frame rod circuit to the operation end timing of the valve opening circuit as described above,
The load current at the beginning of the ignition operation can be reduced. Therefore, according to the present invention, when the battery is used as the power source for the combustion control circuit, it is possible to suppress the variation in the life due to the individual difference of the battery, and the battery is exhausted before the designated replacement of the battery, and the user is informed. It is possible to prevent problems such as inconvenience. Further, when a power supply circuit for converting alternating current from a commercial power supply into direct current is used as a power supply for a combustion control circuit, components such as a transformer and a silicon bridge that constitute the power supply circuit can be made small with a small rating, It is possible to downsize the device and reduce the cost.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment in which the present invention is applied to a combustion control circuit of a water heater 1 shown in FIG. 1 will be described.

The water heater 1 comprises a gas burner 2 and a heat exchanger 3 which uses the gas burner 2 as a heat source, and further has a water system valve unit 5 connected to a water pipe joint 4 at the lower end and a gas at the lower end. The gas system valve unit 7 connected to the pipe joint 6 is provided.

On the downstream side of the water system valve unit 5, a heat exchange channel 8 passing through the heat exchanger 3 and a bypass channel 9 are connected, and the downstream end of the heat exchanger 8 and the downstream end of the bypass channel 9 are connected to each other. Are joined by a mixing section 10 provided at the center of the lower end of the water heater 1, and a hot water outlet head 11 is connected to the mixing section 10 via a flexible tube 12.

The water system valve unit 5 is constructed so as to carry out the water flow by pushing the operator 13 and the amount of water flow to the both water passages 8 and 9 by the turning operation of the operator 13. The structure is not particularly different from the conventionally known structure, and its detailed description is omitted.

As shown in FIG. 2, the gas system valve unit 7 is opened by pressing from the upstream side by an electromagnetic safety valve 14 and a rod 15a interlocking with a water governor provided in the water system valve unit 5 during water passage. A water pressure responsive valve 15, a gas governor 16, and a gas amount adjusting valve 17 that interlocks with an operating lever 17a on the front surface of the water heater 1 via a gear 17b are provided.

When the operator 13 is pushed to pass water, the water pressure responsive valve 15 is opened and the dog 18 on the rod 15a is opened.
The switch 18 cooperating with a is turned on by the movement of the dog 18a, the electromagnetic safety valve 14 is opened as described later, gas is supplied to the burner 2 and it is ignited.

The water heater 1 is provided with an ignition plug 19, a frame rod 20, and a flame detecting thermocouple 21 facing the burner 2 and further facing the heat exchanger 3. A thermocouple 22 for detecting oxygen deficiency is provided.

FIG. 3 shows a combustion control circuit, and the power source of the circuit is composed of a battery 31. Here, the electromagnetic safety valve 1
The electromagnet 4 has a first coil 14a having a small resistance value,
The second coil 14b having a large resistance value is wound.
Then, in the combustion control circuit, a valve opening circuit 23 that energizes the first coil 14a to forcibly open the electromagnetic safety valve 14 by an electromagnetic force, and an electromagnetic safety valve 14 that energizes the second coil 14b.
And a holding circuit 24 for adsorbing and holding the valve in an open state.

The combustion control circuit further includes a spark plug 19
From the two thermocouples 21 and 22 connected in reverse polarity to each other, with an ignition circuit 25 for causing a spark discharge in the above, a flame rod circuit 26 for detecting ignition of the burner 2 from an electric current flowing through the flame rod 20, and A misfire / oxygen deficiency detection circuit 27 for inputting electromotive force is provided. Here, the frame rod circuit 26 outputs a high level signal when a current is flowing through the frame rod 20, that is, at the time of ignition, and when a current is not flowing through the frame rod 20, that is, a low level signal when there is a misfire. Is output. Further, the misfire / oxygen deficiency detection circuit 27 outputs a high level signal when the electromotive force input thereto is equal to or higher than a predetermined ignition determination value, and the electromotive force of the thermocouple 21 decreases due to the misfire of the burner 2, Alternatively, the thermocouple 22 is heated by the lift-up of the burner flame during oxygen deficiency, the electromotive force of the thermocouple 21 is offset by the electromotive force of the thermocouple 22, and the input electromotive force falls below the predetermined misfire / oxygen deficiency determination value. When it becomes, it outputs a low level signal.

Further, the switch 1 is provided in the combustion control circuit.
First to third timer circuits 28 ₁ , 28 ₂ , 28 ₃ are provided which start the time counting operation when 8 is turned on. The first timer circuit 28 ₁ outputs a high level signal for a predetermined first set time T1 (for example, 0.4 seconds) from the time when the switch 18 is turned on, and the high level signal from the first timer circuit 28 ₁ is output. Open circuit 23 by the output signal of
To activate the first coil 14a to energize the electromagnetic safety valve 14
Is forcibly opened.

The second timer circuit 28 ₂ outputs a high level signal for a second set time T2 (for example, 0.8 seconds) set longer than the first set time T1 after the switch 18 is turned on. A high level output signal from the second timer circuit 28 ₁ activates the ignition circuit 25 and activates the holding circuit 24 to energize the second coil 14b to attract and hold the electromagnetic safety valve 14 in the open state. It has become.

The third timer circuit 28 ₃ corresponds to the third waiting time corresponding to the heating waiting time of the thermocouple 21 from the time when the switch 18 is turned on.
It outputs a high level signal during the set time T3 (for example, 30 seconds), and the output signal from the third timer circuit 28 ₃ is input to the AND circuit 29.

A signal output when the valve opening circuit 23 is operating is further input to the AND circuit 29 through the NOT circuit 30. Thus, the operation of the valve opening circuit 23 is completed and the NOT circuit is completed. AND circuit 2 until the third set time T3 elapses when the signal from 30 becomes high level
A high level signal is output from 9, and the frame rod circuit 26 is operated by this output signal.

The holding circuit 24 includes a second timer circuit 28 ₂
In addition to the output signal of the above, the output signals of the flame rod circuit 26 and the misfire / oxygen deficiency detection circuit 27 are input, and thus, even when a high level signal is output from each of the circuits 26 and 27, it is held. The circuit 24 is activated to energize the second coil 14b.

According to the above construction, when the switch 18 is turned on by the ignition operation, that is, the water flow by the pushing operation of the operator 13, as shown in FIG. 4, the first set time T1 from the time when the switch 18 is turned on. The valve opening circuit 23 is operated only for the second set time T2 and the holding circuit 24 and the ignition circuit 25 are operated.
Are operated, the electromagnetic safety valve 14 is forcibly opened by the electromagnetic force, is adsorbed and held in the open state, and the burner 2 is ignited. Then, when the operation of the valve opening circuit 23 is completed after the elapse of the first set time T1, the operation of the frame rod circuit 26 is started, and if the burner 2 is ignited, the flame is maintained even after the elapse of the second set time T2. The holding circuit 24 is continuously operated by a signal from the rod circuit 26, and the combustion of the burner 2 is continued. Although not shown in FIG. 4, a required electromotive force is generated from the thermocouple 21 before the operation of the frame rod circuit 26 ends after the third set time T3 has elapsed from the time when the switch 18 is turned on, and after T3 elapses. The combustion of the burner 2 is continued by the operation of the holding circuit 24 by the signal from the misfire / oxygen deficiency detection circuit 27.

Here, the load current of the valve opening circuit 23 is 410
The load current of the holding circuit 24 is about 6 mA, the load current of the ignition circuit 25 is about 80 mA, and the load current of the frame rod circuit 26 is about 20 mA.
When all the circuits 23, 24, 25, 26 are operated at the time of turning on, the maximum load current becomes 516 mA, but in the present embodiment, the operation of the frame rod circuit 26 is started when the operation of the valve opening circuit 23 is completed. Therefore, the maximum load current is 49
It becomes 6mA. Thus, the maximum load current is 500mA
Therefore, the variation in the utilization rate due to the individual difference of the battery shown in FIG. 5 is suppressed to a small level, and the problem that the battery is exhausted earlier than the designated replacement period of the battery and the user is inconvenient does not occur.

Further, in the above embodiment, the battery is used as the power source of the combustion control circuit, but as shown in FIG. 6, the combustion control circuit using the power source circuit 33 for converting the alternating current from the commercial power source 32 into the direct current is also used. It can be configured similarly to the above. According to this, since the maximum load current is reduced as described above, the transformer 34 and the silicon bridge 35 which form the power supply circuit 33.
As such parts, small parts having a small rating can be used, and the size and cost of the device can be reduced.

Although the embodiment in which the present invention is applied to the combustion control circuit of the water heater has been described above, the present invention is similarly applied to the combustion control circuit of other combustors such as a cooking combustor and a heater. it can.

[Brief description of drawings]

FIG. 1 is a front view of an example of a water heater to which the circuit of the present invention is applied.

FIG. 2 is a schematic sectional view of a gas valve unit provided in a water heater.

FIG. 3 is a block diagram of an example of the present invention.

FIG. 4 is a time chart showing the operation timing of each circuit.

FIG. 5 is a diagram showing a relationship between a load current of a battery and a utilization rate.

FIG. 6 is a block diagram showing another embodiment in which the power supply is changed.

[Explanation of symbols]

 2 burner 14 electromagnetic safety valve 20 frame rod 23 valve opening circuit 24 holding circuit 25 ignition circuit 26 frame rod circuit 31 battery 32 commercial power supply 33 power supply circuit

Claims (2)

[Claims] 1. A combustion control circuit using a battery as a power source, the ignition circuit igniting a burner, and a valve opening circuit forcibly opening an electromagnetic safety valve provided in a fuel supply path to the burner with electromagnetic force. And a holding circuit that adsorbs and holds the electromagnetic safety valve in the open state, and detects ignition of the burner using the frame rod,
A flame rod circuit for adsorbing and holding the electromagnetic safety valve in an open state when the burner is ignited, and during the ignition operation, the valve opening circuit is operated for a first set time, and the ignition circuit and the holding circuit are also operated. A combustion control circuit, which is operated for a second set time set longer than the set time of 1, and starts the operation of the flame rod circuit when the operation of the valve opening circuit is completed. 2. A combustion control circuit using a power supply circuit for converting an alternating current from a commercial power supply to a direct current as a power supply, wherein an ignition circuit for igniting a burner and an electromagnetic safety valve provided in a fuel supply path to the burner are electromagnetic. The open circuit forcibly opening the valve with force, the holding circuit for holding the electromagnetic safety valve in the open state by suction, and the flame rod are used to detect the ignition of the burner, and the electromagnetic safety valve is opened when the burner is ignited. A frame rod circuit for adsorbing and holding the valve in an open state, the valve opening circuit is operated for a first set time during ignition operation, and the ignition circuit and the holding circuit are set longer than the first set time. A combustion control circuit, which is operated for a set time, and when the operation of a valve opening circuit is completed, the operation of a flame rod circuit is started.