JPH10281461A - Incomplete-combustion preventing apparatus for gas water heater - Google Patents

Abstract

PROBLEM TO BE SOLVED: To eliminate stop of a gas water heater when a het exchanger is clogged by obviating closing of a gas solenoid valve while flame current reduced by a lift of the flame temporarily generated after ignition is recovered to a predetermined value. SOLUTION: A holding current of a holding coil is not stopped even if a flame current becomes a decision value or less until a predetermined time T2 is elapsed from the time point of stopping an operation of an igniting circuit after the flame current arrives at the decision value so that the ignition is confirmed. Accordingly, in the case of igniting a main burner 20, a flow of combustion waste gas returned from a circulating tube 13 to a burner port 22 is abruptly increased, a lift occurs at the ignited flame, and the flame current is reduced to a predetermined value or lower as long as it is temporary after the ignition. Thus, even if the valve is closed, stop of the heater is not executed. This predetermined time T is the time until the flame current reduced to the lift of the flame temporarily occurred after the ignition at the time of the degree that a blocking ratio is of the degree that it is not disturbed for use from confirmation of the ignition to the burner 20 is recovered to a predetermined value.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a device for preventing incomplete combustion used in a gas water heater in which a heat exchanger provided above an inner skirt is heated by a burner.

[0002]

2. Description of the Related Art A device for preventing incomplete combustion of a gas water heater of this kind is disclosed in Japanese Patent Application No. 8-328522 previously proposed by the applicant.
There is a technology related to the issue. This is because a flame rod 3 for detecting a flame above a part of a flame opening 22 of a main burner 20 (a reference numeral refers to the embodiment of the present invention shown in FIG. 1).
8 and a return pipe portion 1 whose upper end is opened into the inner skirt 10 below the heat exchanger 12 and opened toward the flame opening 22 provided with a frame rod 38 at the lower portion.
This is provided with a reflux tube 13 having 3b. According to this technology, when the oxygen concentration in the room decreases, a lift occurs in the flame, and when the heat exchanger 12 or the like becomes clogged, the pressure in the upper portion of the inner body skirt 10 increases, and the combustion waste is increased. Since the gas is returned to the vicinity of the flame port 22 through the reflux pipe 13, a lift is generated in the flame generated in the flame port, and in any case, the gas current is reduced by utilizing the phenomenon that the flame current passing through the frame rod 38 is reduced. Valve 26 can be closed to prevent incomplete combustion. Further, misfire can be detected without a time delay.

[0003] However, this Japanese Patent Application No. 8-328522.
According to the technique of No. 2, when the burner 20 is ignited, the pressure in the inner body skirt 10 instantaneously increases, and the flow of the combustion waste gas returned from the return pipe 13 to the flame port 22 provided with the frame rod 38 suddenly increases. To cause a temporary lift in the flame and reduce the flame current, so that the gas solenoid valve 26 may be closed to stop the gas water heater. In order to solve such a problem, this technique employs a reflux pipe 13 extending downward.
The lower end of the main body portion 13a is released to the outside, and a return pipe portion 13b opened toward the flame port 22 provided with the frame rod 38 is branched from the middle of the main body portion 13a. The rapid flow of the combustion waste gas generated therein is discharged to the outside mainly from the opening at the lower end of the main body portion 13a by inertia, so that the amount of the combustion waste gas flowing from the return pipe portion 13b to the flame outlet 22 is reduced.

[0004]

However, in this technique, if the distance from the branch to the return pipe portion 13b to the opening at the lower end of the main body portion 13a is increased, the combustion waste gas returning to the flame port 22 due to the resistance of this long portion. Therefore, it is difficult to prevent the gas solenoid valve 26 from closing due to the temporary lift of the flame generated at the time of ignition. Further, if this distance is shortened, the temporary lift of the flame generated at the time of ignition can be reduced to prevent the gas solenoid valve 26 from closing, but
In the steady use state, when the heat exchanger 12 or the like becomes clogged, the amount of combustion waste gas returned to the flame port 22 is reduced, and the flame current does not decrease to the determination value, thereby achieving the original purpose of preventing incomplete combustion. Becomes difficult. In short, this 2
There is a problem that it is difficult to satisfy the two objectives at the same time. An object of the present invention is to solve such a problem by devising a control means for stopping a gas water heater when an abnormality is detected by detecting a flame current.

[0005]

For this purpose, the apparatus for preventing incomplete combustion of a gas water heater according to the present invention comprises an inner skirt, a heat exchanger provided continuously above the inner skirt, It has a burner provided at the bottom of the inner trunk skirt,
The present invention relates to a gas water heater in which feed water passing through a heat exchanger is heated by a burner, and includes an ignition circuit having an ignition plug for igniting fuel gas ejected from the burner, and a normal operation above a flame outlet of the burner. In the combustion state, a flame rod located in the flame generated in the flame outlet, and applying a voltage to the flame rod to detect a flame current passing through the flame rod, and if the flame current is equal to or less than a predetermined determination value, A burner controller that closes a gas solenoid valve that supplies fuel gas to the burner is provided.The burner controller detects a flame current that increases immediately after ignition of the gas water heater and stops the operation of the ignition circuit from the time when the ignition circuit is stopped. When the blockage rate of the passage area of the waste gas passage is at a level that does not interfere with use, the flame current reduced by the flame lift temporarily generated after the above-described ignition turns to a predetermined judgment value. During a predetermined time required to it is characterized in that it has not performed the operation described above to close the gas solenoid valve. With this configuration, when the burner is ignited, the flow of the combustion waste gas returned from the return pipe to the flame port provided with the frame rod sharply increases to cause a lift in the flame, and the flame current is determined by a predetermined value. Even if it decreases below the value,
As long as it is temporary that usually occurs after ignition
The burner controller does not close the gas solenoid valve.

Further, the incomplete combustion prevention device for a gas water heater according to the present invention is a gas water heater similar to the preceding item, which has a similar ignition circuit and a frame rod, and applies a voltage to the frame rod. A flame current passing through the frame rod is detected, and if the flame current is equal to or less than a predetermined determination value, a burner controller for closing a gas solenoid valve for supplying a fuel gas to the burner is provided. From the point at which ignition of the
During a predetermined time required for the flame current reduced by the flame lift temporarily generated after ignition to recover to a predetermined determination value when the blockage rate of the passage area of the combustion waste gas passage is at a level that does not interfere with use, The above operation of closing the gas solenoid valve may not be performed. Also in this case, as in the case of the preceding paragraph, even if the flame current may decrease below a predetermined judgment value at the time of ignition of the burner, as long as it is a temporary one which normally occurs after ignition, the burner controller Does not close the gas solenoid valve.

In the above-described incomplete combustion preventing device for each gas water heater, the predetermined judgment value of the flame current may be the same before and after the period in which the burner controller does not perform the above-described operation of closing the gas solenoid valve. preferable.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The accompanying drawings show an embodiment in which the present invention is applied to a gas instantaneous water heater. As shown in FIG. 1, a heat exchanger 12 composed of heat transfer tubes 12a and fins 12b is provided above an inner skirt 10 forming a combustion chamber 14 of a gas instantaneous water heater, and a main burner is provided below. 2
0 is provided. The inlet side of the heat transfer pipe 12a is connected to a water supply pipe 15 via a preheating pipe 11 wound around the inner body skirt 10, and a hot water supply plug 17 is provided on a hot water supply pipe 16 connected to the outlet side. The water supply pipe 15 is provided with a water-side controller 18 using a diaphragm that moves a rod 18a to operate a water pressure responsive valve 28 and a water flow switch 31 described later when the amount of water supply exceeds a predetermined amount. Although not shown, the water side controller 18 has a water supply pipe 15.
There is provided a manual valve for manually adjusting the flow rate from the air to the heat exchanger 12 to adjust the tap water temperature.

As shown in FIG. 1, the main burner 20
The fuel gas is supplied via a gas supply pipe 25 in which a gas solenoid valve 26, a capacity adjusting valve 27, and a water pressure responsive valve 28 are provided in series.
The gas solenoid valve 26 is controlled to be opened and closed by a current flowing from the burner controller 30 to the operating coil 26a, and the capacity adjustment valve 27 is manually adjusted to adjust the gas supply amount to the main burner 20 so that the hot water is supplied. It changes the tapping capacity of the vessel. The water pressure responsive valve 28 is a heat exchanger 1
2 is opened and closed by the rod 18a of the water-side controller 18 so as to be opened when a predetermined amount or more of water is supplied. As soon as the hydraulic valve 28 is opened, the rod 18
The cam 18b provided at a turns on the water flow switch 31.

Each burner unit 21 is made of sheet metal and has a large number of flame ports 22 arranged in two rows as shown in FIGS. 1 and 2, and each flame port 22 is partitioned by a partition plate 22a. Have been. Above one of the outermost rows of flame ports 22, a horizontally bent tip of a frame rod 38 supported by an insulator 38a is created in the flame port under normal combustion conditions. It is inserted from the outside that is almost perpendicular to the row of flame ports 22 so as to be located in the flame 23. The tip of the frame rod 38 is folded in a horizontal plane in order to increase the contact area with the flame 23.

Immediately below the heat exchanger 12, an upper end is formed in a combustion chamber 14 through a hole provided in a side wall of the inner skirt 10.
The main body 13a of the reflux pipe 13 opened to the upper part of the pipe extends straight downward along the outer side of the side wall of the inner skirt 10, and the lower end is opened to the atmosphere in the gas water heater and branches from the middle. The return pipe portion 13b of the burned waste gas passes through a notch formed in the lower portion of the inner trunk skirt 10 and is opened obliquely toward the flame outlet 22 forming the flame 23 into which the frame rod 38 is inserted. . The return pipe portion 13b is deformed so that its cross-sectional shape becomes a horizontally long rectangle except for the base portion connected to the main body portion 13a, and the height of the center plane thereof is
2 corresponds to the upper end surface of the burner unit 21.

Next, an outline of the burner controller 30 will be described with reference to FIG. In this embodiment, the power source 40 is a dry battery, and the voltage monitor circuit 32, the solenoid valve drive circuit 33, the ignition circuit 34, the timer circuit 35, the constant voltage circuit 36, the frame guard circuit 37, and the safety The circuit 39 is connected. Solenoid valve drive circuit 33
Receives an input from the timer circuit 35, passes a current through the operating coil 26a to open the gas solenoid valve 26, activates the ignition circuit 34, ignites the burner 20 by the ignition plug 34a, and If the detected value of the flame current input from the circuit 37 is equal to or less than a predetermined determination value, the current to the operation coil 26a is stopped and the gas solenoid valve 26 is closed. The operating coil 26a has an adsorption coil 26b that needs to flow a large current to open the closed gas solenoid valve 26, and a holding device that only needs to flow a small current to keep the gas solenoid valve 26 once opened. It consists of a coil 26c.

The frame guard circuit 37 includes a constant voltage circuit 36.
Receiving a constant voltage output from the
A predetermined voltage is applied to the solenoid valve driving circuit 33 to detect a flame current passing through the frame rod 38 and to output a signal corresponding to the detected value.
Is output to Since the flame current changes instantaneously in response to the change of the flame, the output of the signal to the solenoid valve driving circuit 33 is performed substantially without a time delay. The frame guard circuit 37 is provided with a replaceable gas type connector 37a in order to adjust the above-mentioned determination value according to the type of gas used. The safety circuit 39 monitors whether there is an abnormality in the operation of the frame guard circuit 37, and stops the operation of the gas water heater when an abnormality occurs. When the voltage of the power supply battery 40 falls below a predetermined limit, the voltage monitoring circuit 32 turns on the indicator light 32a to urge replacement of the battery.

Next, the flow chart shown in FIG.
The operation of the above embodiment will be described with reference to a characteristic diagram shown in FIG. If the water supply through the water supply pipe 15 exceeds a predetermined amount by opening the hot water tap 17, the water pressure switch 28 is opened and the water flow switch 31 is turned on at the same time (step 10).
0), the burner controller 30 starts a first hour counting of t ₁ of the first timer built (Step 10
1) Whether or not the voltage of the power supply battery 40 is equal to or higher than a predetermined value (for example, 1.9 volts) (Step 102) and whether or not the gas type connector 37a is connected (Step 103).
Check. If either one of steps 102 and 103 is NO, the burner controller 30 performs an abnormality display by an indicator lamp or a buzzer (step 109), and stops the further operation of the gas water heater.

If both steps 102 and 103 are YES, the burner controller 30 applies an attraction current to the attraction coil 26b of the gas solenoid valve 26, opens it, and simultaneously activates the ignition circuit 34 (step 10).
4) The main burner 2 is activated by a spark generated in the spark plug 34a.
It is determined whether the flame current flowing through the frame rod 38 detected by the frame guard circuit 37 is greater than or equal to a predetermined determination value I ₀ (for example, 1 μA) by igniting the fuel gas ejected from the flame port 22 of 0. Step 105). As the first hour t ₁ if this flame current before reaching the first predetermined time T ₁ (e.g., 2 seconds) does not reach the determination value I _0, it is poor combustion state by an ignition miss or for some reason, The burner controller 30 stops the operation of the ignition circuit 34 (step 107), stops the suction current to the suction coil 26b (step 108), closes the gas solenoid valve 26, and stops the supply of the fuel gas to the main burner 20. Then, an error is displayed (step 109), and the further operation of the gas water heater is stopped.

If the flame current exceeds the judgment value I ₀ before the first time t ₁ reaches the first predetermined time T ₁ , that is, if the combustion state is normal, the burner controller 30 applies the current to the adsorption coil 26b. Holding coil 26
switching to a small holding current to be applied to the gas solenoid valve 26
Was held open, the operation of the ignition circuit 34 is stopped, and starts the second time counting of t ₂ of the second timer built (step 110). As a result, the operation of the gas water heater is started, and water supplied through the heat exchanger 12 is supplied to the main burner 2.
The water is heated by 0 and the hot water is supplied from the hot water tap 17.

After the second time t ₂ has passed the second predetermined time T ₂ (for example, 10 seconds) (step 111) in this hot water supply state (step 111), the burner controller 30 sets the frame guard circuit 3
Whether the flame current passing through the frame rod 38 detected by the switch 7 is equal to or greater than a predetermined determination value I ₀ (for example, 1 μA as described above) (step 112), and whether the water flow switch 31 is on ( Step 113) is repeatedly checked. When the hot water tap 17 is closed, the water pressure control valve 28 is closed via the water side controller 18 and at the same time, the water flow switch 3 is turned off.
Since 1 is turned off, the burner controller 30 stops the holding current to the holding coil 26c (step 114).
The gas solenoid valve 26 is closed, the supply of the fuel gas to the inburner 20 is stopped to stop the operation of the gas water heater, and then the process returns to the standby state before the hot water tap 17 is opened. Note that the check in step 113 is that the second time t2 is the second predetermined time.
It may be performed even before T2 elapses.

If the incomplete combustion occurs due to the following reasons and the flame current decreases to the judgment value I ₀ or less while the hot water is repeatedly discharged from step 112 and step 113, the burner controller 30 sets the suction coil. The adsorption current to 26b is stopped (step 108), the gas solenoid valve 26 is closed, and the supply of fuel gas to the main burner 20 is stopped.
An abnormality display is performed (step 109), and the further operation of the gas water heater is stopped.

Next, the action of preventing incomplete combustion due to individual causes will be described in detail. First, although the oxygen concentration in the air is normal in the normal use state, the fins 12b of the heat exchanger 12 provided on the upper side of the inner trunk skirt 10 are clogged by combustion products or the like, and the air flow becomes poor. The case where the amount of combustion air is insufficient will be described. As the blocking rate of the passage area of the combustion waste gas passage due to such clogging increases, the inner trunk skirt 10, the heat exchanger 12, the main burner 2
The pressure in the upper part in the combustion chamber 14 formed during 0 gradually increases. In the embodiment in which the recirculation pipe 13 is provided as shown in FIG.
As the pressure in the upper part of the inner space 4 increases, the upper part of the combustion chamber 14 is returned from the main body part 13a of the reflux pipe 13 to the vicinity of the flame port 22 provided with the frame rod 38 through the return pipe part 13b as shown by the solid arrow. The combustion waste gas gradually increases.

As a result, the oxygen concentration of the combustion air in the vicinity of the flame port 22 decreases, so that the flame generated in the flame port 22 gradually lifts, and the length of the unburned gas portion generated at the base of the flame decreases. The tip of the frame rod 38, which gradually increases and is in the burning flame in the normal combustion state, gradually moves into the unburned gas portion. Therefore, as shown in FIG.
The flame current through the frame rod 38 gradually decreases as the occlusion rate increases. Burner controller 30 holds the coil 26 if the value of the flame current with a predetermined determination value I ₀ or less
The holding current for c is stopped (steps 112 and 108), an abnormality is displayed (step 109), and the operation of the gas water heater is stopped. The limit of the clogging rate that can be used in the gas water heater varies depending on the model, for example, 37%.
On the order, occlusion rate was set a determination value I ₀ to stop the operation of the gas water heaters An increase to this extent.

Although the passage of the combustion air is not clogged, if the oxygen concentration in the surrounding air gradually decreases due to continued use of the gas water heater without sufficient ventilation, the oxygen concentration may be reduced. Flame mouth 2 of main burner 20 according to decrease
2, the length of the unburned gas generated at the base of the flame gradually increases. Thus the flame current is gradually decreased so moves the tip of the flame rod 38 that were in the flames that are burning in unburnt portion gradually under normal combustion conditions, the value of the flame current determination value I ₀ or less , The burner controller 30 stops the holding current to the holding coil 26c (step 112, step 1).
08), an abnormality display is performed (step 109), and the operation of the gas water heater is stopped.

Next, the operation at a time when the flame current is not yet stable after ignition of the main burner 20 will be described in detail. FIG. 5 shows the flame current at the time of a cold start (when the gas water heater is started from a cooling state) when the block rates of the passage area of the combustion waste gas passage are different due to clogging of the fins 12b of the heat exchanger 12, and the like. FIG. 4 is a diagram showing a temporal change of the fuel gas. When the fuel gas is ignited at the start of the operation of the gas water heater, the fuel gas rapidly increases, then temporarily decreases except when the blocking rate is 0%, and increases again. The value converges to the value in the steady state while repeating some increase and decrease. As described above, in this embodiment, the limit of the obstruction rate that cannot be used for use is 37.
%, But the value of the flame current when the clogging rate is 30% is shown in FIG.
As shown in, for about 3-6 seconds after starting the determination value I ₀ or less.

Therefore, as it is, the operation of the gas water heater stops even though the closing rate has not reached the limit. However, in this embodiment, the flame current is
The ignition current is confirmed by reaching I _0, and until the second predetermined time T ₂ elapses from the time point S when the operation of the ignition circuit 34 stops (step 111), the flame current becomes equal to or less than the determination value I _0. Also, the holding current for the holding coil 26c is not stopped. Therefore, when the main burner 20 is ignited, the flow of the combustion waste gas returned from the recirculation pipe 13 to the flame port 22 provided with the frame rod 38 sharply increases, causing a lift in the ignited flame and causing a flame current. Is reduced to a predetermined value or less, the gas solenoid valve is not closed and the gas water heater does not stop operating as long as it is a temporary one that normally occurs after ignition. The second predetermined time T ₂ are, from the ignition confirmation to the main burner 20, decreased flame current predetermined determination value I by the lift temporarily occur flame after ignition when obstruction ratio is approximately Usage no problem _The time required to recover to _0, which is determined in advance by experiments or the like.

[0024] In the above-described embodiment, the determination value I ₀ of the flame current at the time of ignition confirmation performed before the start of the second predetermined time T ₂ (step 105), the second end of the predetermined time T ₂ Since the determination value I ₀ (step 112) of the flame current for preventing incomplete combustion performed later is the same, the control program is simplified accordingly.

In the above-described embodiment, the second predetermined time
Counting start time point T _2, but the flame current ignition circuit 34 to check the ignition by reaching the determination value I ₀ is the point S of stopping the operation, the time counting start point, main under normal operating conditions It is predicted that the ignition of the fuel gas ejected from the burner 20 is surely completed (for example, the first time).
May also as a predetermined end point of time T _1), the second predetermined time T ₂ of the this case is somewhat shorter.

The above embodiment has been described with respect to an example in which the present invention is applied to a gas water heater of a type in which a main burner is directly ignited by an ignition plug. The present invention relates to a system in which a main burner is ignited by a pilot burner. It is also possible to apply the present invention to a gas water heater. In this case, a frame rod may be provided in the pilot burner, and the return pipe portion 13b of the return pipe 13 may be directed to the pilot burner. Further, the present invention is not limited to the gas water heater of the pre-stop type as in the above embodiment, but can be applied to a gas water heater of the original stop type.

[0027]

As described above, according to the present invention, when the burner is ignited, the combustion waste gas returned from the return pipe to the flame port provided with the frame rod causes a lift in the flame, and the flame current is reduced. If the burner controller does not close the gas solenoid valve as long as it is a temporary one that normally occurs after ignition, even if the heat exchanger is reduced below the judgment value, if the heat exchanger becomes clogged in normal use conditions Even if a reflux tube that can achieve the purpose of preventing incomplete combustion is used,
The temporary decrease in the flame current at the time of ignition prevents the gas solenoid valve from closing and the gas water heater from stopping.

If the predetermined determination value of the flame current is the same before and after the period in which the burner controller does not perform the above-described operation of closing the gas solenoid valve, the control can be simplified.

[Brief description of the drawings]

FIG. 1 is a view showing an entire structure of an embodiment of a device for preventing incomplete combustion of a gas water heater according to the present invention.

FIG. 2 is a partially enlarged top view taken along line 2-2 of FIG.

FIG. 3 is a configuration diagram of a burner controller of the embodiment shown in FIG.

FIG. 4 is a flowchart showing the operation of the embodiment shown in FIG.

FIG. 5 is a diagram showing a temporal change characteristic of a flame current from the start of operation in the embodiment shown in FIG. 1;

FIG. 6 is a diagram showing a change characteristic of a flame current with respect to a closing rate in the embodiment shown in FIG. 1;

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 10 ... Inner trunk skirt, 12 ... Heat exchanger, 20 ... Burner (main burner), 22 ... Flame port, 26 ... Gas solenoid valve, 3
0: burner controller, 34: ignition circuit, 34a: ignition plug, 38: frame rod.

Claims (3)

[Claims] 1. An inner body skirt, a heat exchanger provided continuously above the inner body skirt, and a burner provided below the inner body skirt, and water supply passing through the heat exchanger. In the gas water heater, which is heated by the burner, an ignition circuit having an ignition plug for igniting the fuel gas ejected from the burner, and the same in the normal combustion state above the burner of the burner A flame rod positioned in the flame to be generated, and a voltage is applied to the flame rod to detect a flame current passing through the flame rod. If the flame current is equal to or less than a predetermined determination value, fuel gas is supplied to the burner. A burner controller that closes the gas solenoid valve to be turned on.The burner controller detects the flame current that increases immediately after the ignition of the gas water heater and stops the operation of the ignition circuit, A predetermined time required for the flame current reduced by the flame lift temporarily generated after the increase to recover to the predetermined determination value when the blockage rate of the passage area of the combustion waste gas passage is at a level that does not interfere with use. During the period, the above-described operation of closing the gas solenoid valve is not performed, and the incomplete combustion prevention device for the gas water heater is characterized in that it is not performed. 2. An inner body skirt, a heat exchanger provided continuously above the inner body skirt, and a burner provided below the inner body skirt, wherein water is supplied through the heat exchanger. In the gas water heater, which is heated by the burner, an ignition circuit having an ignition plug for igniting the fuel gas ejected from the burner, and the same in the normal combustion state above the burner of the burner A flame rod positioned in the flame to be generated, and a voltage is applied to the flame rod to detect a flame current passing through the flame rod. If the flame current is equal to or less than a predetermined determination value, fuel gas is supplied to the burner. A burner controller that closes a gas solenoid valve that performs ignition at a time when it is predicted that ignition of fuel gas ejected from the burner is normally completed in a normal operation state. A predetermined time required for the flame current reduced by a flame lift temporarily generated after ignition to recover to the predetermined determination value when the blockage rate of the passage area of the combustion waste gas passage is at a level that does not interfere with use. Between
An incomplete combustion prevention device for a gas water heater, wherein the above-described operation of closing the gas solenoid valve is not performed. 3. The gas hot water according to claim 1, wherein the predetermined determination value of the flame current is the same before and after a period during which the burner controller does not perform the operation of closing the gas solenoid valve. Incomplete combustion prevention device for the boiler.