JP2859197B2 - Gas Combustor Safety Devices - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

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

[0002]

2. Description of the Related Art A gas combustor has a case in which a gas burner is provided, a fan for supplying combustion gas into the case 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 is provided in the combustion gas passage of the fuel cell and detects a harmful gas component due to incomplete combustion.
When the concentration of O) becomes equal to or higher than a predetermined limit, a gas sensor detects this and stops the gas supply to the gas burner to stop the gas combustor. Such incomplete combustion occurs when the amount of combustion air is reduced due to clogging of combustion products in the fins and exhaust stack of the heat exchanger provided in the case 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. Since the back pressure in the cylinder increases and the amount of combustion air supplied by the fan decreases, the CO concentration temporarily exceeds the limit, and there is an inconvenience that the gas combustor stops.

According to the present invention, when the degree of clogging of the combustion gas passage or blockage of the intake port is small, the rotation speed of the fan is increased to temporarily compensate for the shortage of the air amount. The above-mentioned inconvenience is solved by stopping the gas combustor for the first time when the limit is exceeded, and when the rotation speed of the fan is increased even if the clogging of the combustion gas passage or the blockage of the intake port is slight. Aims to ensure that the warning is always present.

[0005]

To this end, a safety device for a gas combustor according to the present invention is provided as illustrated in the accompanying drawings.
A case 10 having a gas burner 20 provided therein; a fan 25 for supplying an amount of combustion air into the case 10 in accordance with an amount of gas supplied to the gas burner 20; and a combustion gas passage downstream of the gas burner 20 Gas sensor 36 which is provided in the inside and detects harmful gas components due to incomplete combustion
And a safety device for a gas combustor including a control device 30 for stopping supply of gas to the gas burner 20 when the harmful gas component having a predetermined concentration or more is detected by the gas sensor. When the harmful gas component having a concentration equal to or higher than a predetermined concentration 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 thereafter, the harmful gas having a predetermined concentration or higher is detected by the gas sensor. The gas supply to the gas burner 20 is stopped when a gas component is detected, and an abnormal display is always displayed when the rotation speed of the fan 25 is increasing.

If the gas sensor 36 detects a harmful gas component due to incomplete combustion of a predetermined concentration or more during operation of the gas combustor, the control device 30 increases the rotation speed of the fan 25 to compensate for a decrease in the amount of combustion air. After that, the harmful gas component is detected by the gas sensor 36, and when the concentration becomes lower than the predetermined concentration, the operation of the gas combustor is continued. Fan 25
In the state where the rotation speed is increased, an abnormality display is always performed.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS 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 part 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. Fuel gas is supplied by a gas supply path 21 having a proportional solenoid valve 24 and a main solenoid valve 23, and combustion air is supplied by an electric fan 25 provided below the case 10. The source solenoid valve 22 and the main solenoid valve 23 are solenoid valves that open and close only, and the proportional solenoid valve 24 changes the gas supply amount to the gas burner 20 by continuously changing the opening according to the control current. is there. The fan 25 continuously changes its rotation speed to supply combustion air in an amount corresponding to the gas supply amount.

A water flow sensor 37 is provided on a water supply pipe 16 connected to the inlet side of a 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 is provided on a water supply sensor 17. Hot water temperature sensor 38 and hot water tap 1
8 are provided. The feed water from the feed pipe 16 is heated by the gas burner 20 when passing through the heat exchanger 15,
Hot water is supplied from 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 through the hood 11, and a flame sensor such as a frame rod for detecting the presence or absence of the gas burner 20 in the case 10 just above the gas burner 20. A hood 11 is provided with a gas sensor 36 for detecting harmful gases (CO, HmCn, etc.) due to incomplete combustion.

An electronic control unit 30 for controlling the operation of the instantaneous water heater includes a central processing unit (CPU) and 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,
The operation device 31 is connected to the flame sensor 35, the gas sensor 36, the water flow sensor 37, and the hot water temperature sensor 38. A control program and various constants necessary for controlling the operation of the instantaneous water heater are stored in the ROM of the electronic control unit 30.
Stores variables such as the number of detections n described below. 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 operating device 31 and the sensors 35 to 38 and performs predetermined calculations according to the control program, and performs a predetermined calculation on the electromagnetic valves 22 to 24,
The output to the fan 25, the operation device 31, and the like is performed to control the operation of the instantaneous water heater.

FIGS. 2 and 3 are flowcharts of a control program for controlling the operation of the instantaneous water heater.
Thus, the present embodiment will be described.

FIG. 2 is a flowchart of the main program. When the power of the electronic control device 30 is turned on and the electronic control device 30 is operated by an operation switch (not shown), the CPU resets each variable to 0 or a predetermined initial value and starts the control operation according to the main program. .
First, in step 100, the CPU detects the presence or absence of a water flow through the water supply pipe 16 by the water flow sensor 37. Hot water tap 1
If the water flow is not detected by detecting that the hot water tap 18 is opened and the water supply of a predetermined minimum amount or more is detected, the CPU proceeds to step 101 and the CPU proceeds to step 101.
2 and the main solenoid valve 23 are opened, the proportional solenoid valve 24 is set at a predetermined ignition opening, 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
The PU sets t = 0 in step 102, starts measuring the time t by the built-in clock pulse generator, and repeats steps 103 to 105 while the hot water tap 18 is open. In step 103, the CPU detects a harmful gas component in the CO in the combustion gas by the gas sensor 36, as described later. If the concentration does not fall below the predetermined value, the operation of the gas combustor is stopped. If the concentration is equal to or lower than the predetermined concentration, the control operation proceeds to the next step 104, where the CPU compares the tapping temperature detected by the tapping temperature sensor 38 with the tapping temperature set by the operating device 31 so that the tapping temperature becomes the set temperature. The amount of gas supplied to the gas burner 20 is controlled by controlling the degree of opening of the proportional solenoid valve 24, and the rotational speed of the fan 25 is controlled so as to obtain a predetermined air-fuel ratio, thereby controlling the amount of combustion air.

If the hot water tap 18 is closed, the control operation proceeds from step 105 to step 106, in which one of the original solenoid valve 22 and the main solenoid valve 23 is closed with a predetermined time delay from the other, and the two solenoid valves 22 by the flame sensor 35 are closed. , 23 are checked. When the abnormality of the operation of the solenoid valves 22 and 23 is detected, the CPU stops the operation of the gas combustor. When the abnormality is not detected, the CPU sets the built-in clock pulse generator to t = 0 in step 107. , The time t is started, and in step 108, the post-purge is started by setting the fan 25 to a predetermined purge rotation speed. Until the time t reaches a predetermined post-purge time t1 (for example, 5 minutes), the CPU proceeds to steps 109 and 1.
Step 10 is repeated to check for a small amount of gas leak that cannot be detected in step 106. If t> t1 without detecting a gas leak, the CPU stops the fan 25 in step 111 to end the post-purge, and returns the control operation to step 100. Thereafter, each time the hot water tap 18 is opened, the above operation is repeated. The check of the operation of the solenoid valve in step 106 and the check of gas leak in step 109 are not directly related to the present invention.

Next, the 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 a harmful gas component such as CO due to incomplete combustion by the gas sensor 36 every time t2 (for example, 1 minute), and does not detect a harmful gas component having a predetermined concentration or more three times consecutively. As long as the control operation returns to step 104 in FIG. 2, the normal combustion control is repeated. When the number of times of detection of a harmful gas component having a predetermined concentration or more is two or less, the number of detections n is reset to 0 in step 213 each time. When a harmful gas component having a 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 proceeds to step 210 for the first time, 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
, And reset the number of detections n to 0, and
Return to step 104 in the figure. In step 211, an abnormality display such as a blinking of a combustion lamp may be performed. Then, in steps 200 to 204, the CPU again detects a harmful gas component due to incomplete combustion every time t2.

Incomplete combustion is usually caused by clogging of the fins of the heat exchanger 15 and the exhaust stack 12 with combustion products, or a strong wind blows to the vicinity of the exhaust port to the outside, so that the back pressure in the combustion passage increases. Is caused by a decrease in the amount of combustion air from the fan 25. In these cases, since the degree of decrease in the amount of combustion air is small, the incomplete combustion is eliminated by increasing the rotation speed of the fan 25 by 5% to compensate for the decrease in the amount of combustion air. As a result, no harmful gas component having a concentration equal to or higher than the predetermined concentration due to incomplete combustion is not detected in step 202, and the control operation returns from step 202 to step 104 via step 213. Thereafter, until the hot water tap 18 is closed and the gas combustor stops operating, the fan rotation speed in the normal combustion control in step 104 is always increased by 5%, and the control operation is performed from step 202 to step 213.
Then, the process returns to step 104, and the instantaneous water heater operates.

However, if the wind near the exhaust port is extremely strong, or if the intake port of the fan 25 is significantly blocked by foreign matter, the incomplete combustion is eliminated even if the rotation speed of the fan 25 is increased by 5%. Not done. In this case, the harmful gas component having a concentration equal to or higher than the predetermined concentration is detected again three consecutive times in step 202, so that the control operation proceeds to step 210. In this case, since the flag F is set to 1, the CPU advances the control operation to step 214 and performs an abnormal display with a display lamp or a buzzer, etc.
The solenoid valves 22 to 24 are closed, and after-purging is performed by the fan 25 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 rotation 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 of instantaneously stopping the water heater due to a temporary cause such as a strong wind hitting the exhaust port is eliminated. Also, in this case, step 211
If an abnormality is displayed at the same time as the fan rotation speed increases, the user can know that a slight abnormality has occurred, although there is no problem in the immediate use, and if such abnormality continues, Since the fins of the heat exchanger 15 and the exhaust tube 12 are clogged, it can be known that 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 which case, the step of FIG. A flowchart of FIG. 4 (substantially the same as steps 210 to 214 of FIG. 3) may be inserted in place of 214.

Further, the present invention is not limited to an instantaneous gas water heater,
It can be used for other gas combustors.

[0020]

As described above, according to the present invention, when the degree of clogging of the combustion gas passage or the degree of blockage of the intake port is small, the rotation speed of the fan is increased to reduce the shortage of combustion air. Since the operation of the gas combustor can be supplemented, the gas combustor does not stop in such a case, and an abnormality display is always displayed when the rotation speed of the fan is increased. In addition, it is possible to reliably warn of a slight clogging of the combustion gas passage or a blockage of the intake port, which is not likely to cause an immediate use, thereby prompting maintenance.

[Brief description of the 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 a subprogram of an incomplete combustion check which forms a part of the main program of FIG. 2;

FIG. 4 is a flowchart showing a changed 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)

(57) [Claims] 1. A case in which a gas burner is provided, a fan for supplying an amount of combustion air according to a gas supply amount to the gas burner into the case, and a combustion gas passage downstream of the gas burner. A gas sensor provided with a gas sensor for detecting a harmful gas component due to incomplete combustion, and a control device for stopping gas supply to the gas burner when the harmful gas component having a predetermined concentration or more is detected by the gas sensor. In the safety device, when the control device detects the harmful gas component having a concentration equal to or higher than a predetermined concentration by the gas sensor, the control device increases the rotation speed of the fan by a predetermined amount without first stopping the gas supply to the gas burner. When the gas sensor detects the harmful gas component having a predetermined concentration or more, the gas supply to the gas burner is stopped, and A safety device for a gas combustor, wherein an abnormality is always displayed when the rotation speed of the fan is increased.