JPH08233262A - Safety device for gas combustor - Google Patents

Abstract

PURPOSE: To improve the using handiness by making a safety device of a gas combustion apparatus operate only when it is absolutely necessary. CONSTITUTION: In a case 10 where a gas burner is provided, an amount, which corresponds with a gas feeding amount, of air for combustion is fed by a fan 25, and on the downstream side of the gas burner 20, a gas sensor 36 which detects a harmful gas due to an incomplete combustion is provided. A control device 30 first increases the rotating speed of the fan 25 by a specified quantity, without stopping the gas feeding to the gas burner, when the gas sensor 36 detects a harmful gas component at a specified concentration or higher, then the control device 30 stops the gas feeding to the gas burner 20 when the gas sensor 36 detects the harmful gas component at a specified concentration or higher after the increase of the rotating speed of the fan 25. However, the increase of the rotating speed of the fan 25 or the stop of the gas feeding to the gas burner 20 is performed when the gas sensor 36 continuously detects the harmful gas component at a specified concentration or higher, a plurality of times with a specified time interval.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a gas combustor safety device in which incomplete combustion is prevented by a gas sensor.

[0002]

2. Description of the Related Art A gas combustor has a case provided with a gas burner therein, a fan for supplying combustion air in an amount corresponding to the amount of gas supplied to the gas burner, and a downstream side of the gas burner. A gas sensor provided in the combustion gas passage for detecting a harmful gas component due to incomplete combustion, and a harmful gas component (for example, C
In some cases, when the concentration of O) exceeds a predetermined limit, it is detected by a gas sensor, the gas supply to the gas burner is stopped, and the gas combustor is stopped. Such incomplete combustion occurs when the amount of combustion air decreases due to clogging of the fins of the heat exchanger and exhaust pipe provided in the case with combustion products, and partial blockage of the intake port due to foreign matter. There are many.

[0003]

However, the CO concentration in the combustion gas changes due to various external conditions in addition to the above-mentioned causes. For example, even if it is temporarily caused by a strong wind hitting the vicinity of the exhaust port to the outside, the CO concentration is eliminated. Since the back pressure in the cylinder rises and the amount of combustion air supplied by the fan decreases, there is the inconvenience that the CO concentration temporarily exceeds the limit and the gas combustor stops.

In the present invention, when the amount of combustion air is insufficient, the rotational speed of the fan is increased to temporarily compensate for the insufficient amount of air, and when the concentration of harmful gas components such as CO exceeds the limit. For the first time, stop the gas combustor,
Moreover, it is an object to eliminate the inconvenience by increasing the rotation speed of the fan or stopping the gas combustor only when it is really necessary.

[0005]

To this end, a safety device for a gas combustor according to the present invention has the following features as illustrated in the accompanying drawings.
A case 10 having a gas burner 20 provided therein, a fan 25 for supplying combustion air into the case 10 in an amount corresponding to the amount of gas supplied to the gas burner 20, and a combustion gas passage downstream of the gas burner 20. A gas sensor 36 provided inside to detect harmful gas components due to incomplete combustion
In the safety device of the gas combustor, which is provided with the control device 30 that stops the gas supply to the gas burner 20 when the harmful gas component having a predetermined concentration or more is detected by the gas sensor, the control device 30 uses the gas sensor 36. When the harmful gas component having a predetermined concentration or higher is detected, first, the rotation speed of the fan 25 is increased by a predetermined amount without stopping the gas supply to the gas burner 20, and then the gas sensor 36 causes the harmful gas to have a predetermined concentration or higher. When the gas component is detected, the gas supply to the gas burner 20 is stopped, and the rotation speed of the fan 25 is increased or the gas supply to the gas burner 20 is stopped by the gas sensor 36 after a predetermined time. This is to be performed when the harmful gas component above a predetermined concentration is detected multiple times in succession. It is an feature.

If the gas sensor 36 detects a harmful gas component due to incomplete combustion at a predetermined concentration or higher during operation of the gas combustor, the controller 30 increases the rotation speed of the fan 25 to compensate for the decrease in the combustion air amount. After that, the harmful gas component is detected by the gas sensor 36, and when the concentration is lower than the predetermined concentration, the operation of the gas combustor is continued, and when the concentration is lower than the predetermined concentration, the gas supply is stopped and the gas combustor is stopped. Fan 25
The increase of the rotation speed or the stop of the gas combustor is performed when a harmful gas component having a predetermined concentration or higher is continuously detected a plurality of times at a predetermined time.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described below with reference to embodiments shown in the accompanying drawings.

As shown in FIG. 1, a gas burner 20 is provided in a lower portion of a case 10 forming a combustion chamber of an instantaneous water heater, and a main solenoid valve 2 arranged in series from a gas supply source side.
2, the fuel gas is supplied by the gas supply path 21 having the proportional solenoid valve 24 and the main solenoid valve 23, and the combustion air is supplied by the electric fan 25 provided on the lower side of the case 10. The source solenoid valve 22 and the main solenoid valve 23 are solenoid valves that only open and close, and the proportional solenoid valve 24 changes the opening continuously according to the control current and changes the gas supply amount to the gas burner 20. is there. Further, the fan 25 continuously changes the rotation speed and supplies the combustion air in an amount corresponding to the gas supply amount.

A water flow sensor 37 is provided on the water supply pipe 16 connected to the inlet side of the fin-tube type heat exchanger 15 provided in the case 10 above the gas burner 20, and a hot water supply pipe 17 connected to the outlet side. Hot water temperature sensor 38 and hot water tap 1
8 are provided. The water supply from the water supply pipe 16 is heated by the gas burner 20 when passing through the heat exchanger 15,
Hot water is discharged from the hot water tap 18 at a predetermined temperature. The upper part of the case 10 above the heat exchanger 15 is connected to the exhaust pipe 12 via the hood 11, and in the case 10 immediately above the gas burner 20, a flame sensor such as a frame rod for detecting the presence or absence of a flame of the gas burner 20. 35 is provided, and a gas sensor 36 for detecting harmful gas (CO, HmCn, etc.) due to incomplete combustion is provided in the hood 11.

An electronic control unit 30 for controlling the operation of the instantaneous water heater is a central processing unit (CPU), a read-only memory (R).
OM), a writable memory (RAM), and an interface. As shown in FIG. 1, each solenoid valve 22 to 24, a fan 25, and a drive device (all are not shown) are provided.
The operation device 31, the flame sensor 35, the gas sensor 36, the water flow sensor 37, and the hot water temperature sensor 38 are connected. The ROM of the electronic control unit 30 stores a control program and each constant necessary for controlling the operation of the instantaneous water heater, and the RAM.
Variables such as the number of times of detection n described later are stored in. Further, the operating device 31 is provided with various switches, a hot water temperature setting device, various display lamps and the like necessary for operating the instantaneous water heater. The CPU of the electronic control unit 30 inputs signals from the operation unit 31 and the respective sensors 35 to 38 and performs a predetermined calculation in accordance with the control program, and the respective solenoid valves 22 to 24,
The output to the fan 25 and the operation device 31 is performed to control the operation of the instantaneous water heater.

2 and 3 are flow charts of a control program for controlling the operation of the instantaneous water heater,
This will describe the present embodiment.

FIG. 2 is a flow chart of the main program. When the electronic control unit 30 is turned on and the electronic control unit 30 is operated by the operation switch (not shown), the CPU resets each variable to 0 or a predetermined initial value and starts the control operation by this main program. .
First, in step 100, the CPU detects the presence or absence of water flow through the water supply pipe 16 by the water flow sensor 37. Hot water tap 1
If 8 is closed and the water flow is not detected, the control operation does not proceed. However, if the hot water tap 18 is opened and a predetermined minimum amount or more of water is detected, the process proceeds to step 101, where the CPU determines the original solenoid valve 2
2 and the main solenoid valve 23 is opened, the proportional solenoid valve 24 is set to a predetermined ignition opening degree, the fan 25 is operated at a predetermined ignition rotation speed, and an ignition device (not shown) is operated for a predetermined time,
The gas ejected from the gas burner 20 is ignited. Then C
In step 102, the PU sets t = 0 and starts counting the time t by the built-in clock pulse generator, and repeats steps 103 to 105 while the hot water tap 18 is opened. In step 103, the CPU detects the harmful gas component in the CO in the combustion gas by the gas sensor 36 as described later, and if it is equal to or higher than the predetermined concentration, first increases the rotation speed of the fan 25, and the harmful component still detected is detected. The operation of the gas combustor is stopped if the concentration does not fall below the predetermined level. If the concentration is equal to or lower than the predetermined concentration, the control operation is advanced to the next step 104, and the CPU compares the hot water temperature detected by the hot water temperature sensor 38 with the hot water temperature set by the operating device 31 so that the hot water discharge temperature becomes the set temperature. The amount of gas supplied to the gas burner 20 is controlled by controlling the opening degree of the proportional solenoid valve 24, and the rotation speed of the fan 25 is controlled so as to obtain a predetermined air-fuel ratio to control the combustion air amount.

When the hot water tap 18 is closed, the control operation proceeds from step 105 to step 106, and one of the original solenoid valve 22 and the main solenoid valve 23 is closed with a delay of a predetermined time from the other, and both solenoid valves 22 by the flame sensor 35 are closed. , 23 operation check. As a result, if an abnormality in the operation of both solenoid valves 22 and 23 is detected, the CPU stops the operation of the gas combustor, and if no abnormality is detected, the internal clock pulse generator is set as t = 0 in step 107. Thus, the timing of time t is started, and in step 108, the fan 25 is set to a predetermined purge rotation speed and post-purge is started. Until this time t reaches a predetermined post-purge time t1 (for example, 5 minutes), the CPU executes steps 109, 1
10 is repeated, and a small amount of gas leak that cannot be detected in step 106 is checked. If t> t1 without gas leakage being detected, the CPU stops the fan 25 in step 111 to end the post purge, and returns the control operation to step 100. After that, the above operation is repeated every time the hot water tap 18 is opened. The solenoid valve operation check in step 106 and the gas leak check in step 109 are not directly related to the present invention, and thus the details are omitted.

Next, details of the operation of the incomplete combustion check in step 103 will be described with reference to the flowchart of FIG. In steps 200 to 204, the CPU detects the harmful gas component such as CO due to incomplete combustion by the gas sensor 36 at every time t2 (for example, 1 minute), and the harmful gas component having the predetermined concentration or more is not detected three consecutive times. As long as the control operation returns to step 104 in FIG. 2, the normal combustion control is repeated. When the number of times the harmful gas component having the predetermined concentration or more is detected is less than or equal to 2, the number of times of detection n is reset to 0 at step 213 each time. If the harmful gas component having the predetermined concentration or more is detected three times in a row, the CPU advances the control operation from step 204 to step 210. Since the flag F is 0 when the process first proceeds to step 210, the CPU advances the control operation to steps 211 to 213 to increase the rotation speed of the fan 25 by 5% and set the flag F to 1.
, The detection count n is reset to 0, and the control operation is
Return to step 104 in the figure. In step 211, an abnormality display may be performed by blinking a combustion lamp or the like. Then, the CPU performs the steps 200 to 204 again to detect the harmful gas component due to the incomplete combustion every time t2.

In the case of incomplete combustion, normally, the fins of the heat exchanger 15 and the exhaust stack 12 are clogged with combustion products, or strong winds hit the vicinity of the exhaust port to the outside to increase the back pressure in the combustion passage. Caused by the decrease in the amount of combustion air from the fan 25. In these cases, the degree of decrease in the combustion air amount is small, so that the incomplete combustion is eliminated by increasing the rotation speed of the fan 25 by 5% to compensate for the decrease in the combustion air amount. As a result, no harmful gas component having a predetermined concentration or higher due to incomplete combustion is detected in step 202, and the control operation returns from step 202 to step 213 to step 104. After that, until the hot water tap 18 is closed and the gas combustor stops operating, the fan rotation speed in the normal combustion control of step 104 is always increased by 5%, and the control operation is from step 202 to step 213.
Then, the process returns to step 104, and the instantaneous water heater operates.

However, when the wind hitting the vicinity of the exhaust port is extremely strong or the intake port of the fan 25 is significantly blocked by foreign matter, incomplete combustion is eliminated even if the rotation speed of the fan 25 is increased by 5%. Not done. In this case, in step 202, the harmful gas component having the predetermined concentration or higher is detected again three times in succession, so the control operation proceeds to step 210. In this case, since the flag F is 1, the CPU advances the control operation to step 214, and displays an error with a display lamp or a buzzer.
The electromagnetic valves 22 to 24 are closed, and the fan 25 performs after-purging for a predetermined time (for example, 10 seconds) to stop all control operations.

According to the above embodiment, when the shortage of the combustion air amount is slight, the rotational speed of the fan 25 is increased to compensate for the shortage of the combustion air amount and the operation of the instantaneous water heater is continued. Therefore, the inconvenience that the water heater stops instantaneously due to a temporary cause such as strong wind hitting the exhaust port is eliminated. Also in this case, step 211
By displaying the abnormality at the same time as the fan rotation speed increases, the user can know that a minor abnormality has occurred, although there is no problem in using it for the time being, and if such an abnormality continues, Since the fins of the heat exchanger 15 and the exhaust pipe 12 are clogged, it can be known that the cleaning is necessary.

In the embodiment shown in FIGS. 2 and 3, the fan rotation speed is increased only once, but it may be increased twice. In that case, the steps shown in FIG. The flowchart of FIG. 4 (substantially the same as steps 210 to 214 of FIG. 3) may be inserted in place of 214.

The present invention is not limited to the instant gas water heater,
It can also be used in other gas combustors.

[0020]

As described above, according to the present invention, when the degree of clogging of the combustion gas passage and the degree of blockage of the intake port is slight, the rotation speed of the fan is increased to reduce the amount of combustion air. Since the operation of the gas combustor can be continued, the gas combustor will not stop in such a case, and the fan rotation speed will increase or the gas combustor will stop for a certain period of time. Since it is performed when a harmful gas component above a predetermined concentration is detected consecutively,
Incomplete combustion due to temporary strong wind does not increase the rotation speed of the fan or stop the gas combustor. This will stop the gas combustor and increase the fan speed only when it is really needed, and the overall number will be less, which makes the gas combustor easier to use and The burden on is reduced.

[Brief description of drawings]

FIG. 1 is an overall explanatory view showing the structure of one embodiment of a safety device for a gas combustor according to the present invention.

FIG. 2 is a flowchart of a main program of the embodiment shown in FIG.

FIG. 3 is a flowchart of an incomplete combustion check subprogram which is a part of the main program of FIG.

FIG. 4 is a flowchart showing a modified part of a subprogram in a modified embodiment.

[Explanation of symbols]

10 ... Case, 20 ... Gas burner, 25 ...
Fan, 30 ... Control device (electronic control device), 36.
..Gas sensors

Claims (1)

[Claims] 1. A case having a gas burner therein, a fan for supplying combustion air into the case in an amount corresponding to the amount of gas supplied to the gas burner, and a combustion gas passage downstream of the gas burner. Of a gas combustor equipped with a gas sensor for detecting a harmful gas component due to incomplete combustion, and a control device for stopping the gas supply to the gas burner when the harmful gas component having a predetermined concentration or higher is detected by the gas sensor. In the safety device, when the control device detects the harmful gas component having a predetermined concentration or more by the gas sensor, first, the rotation speed of the fan is increased by a predetermined amount without stopping the gas supply to the gas burner, and then the The gas supply to the gas burner is stopped when the harmful gas component having a predetermined concentration or more is detected by the gas sensor. The increase of the rotation speed of the fan or the stop of the gas supply to the gas burner is performed when the gas sensor detects the harmful gas component having a predetermined concentration or more continuously for a predetermined number of times. A gas combustor safety device characterized in that