JPH02150619A - Safety device for gas burner - Google Patents

Abstract

PURPOSE:To eliminate inconvenience which halts the operation of a gas burner when ever a temporary and slight incomplete combustion is generated by increasing a rotary speed of a fan when detecting a harmful gas component whose density is higher than a specified density, and halting the supply of gas to a burner when detecting a harmful gas component whose density is higher than the specified density latter. CONSTITUTION:A CPU detects a harmful gas component produced by incomplete combustion with a gas sensor 36 at an interval of time t2, say, one minute. It is detects a harmful gas component whose density is higher than a specified density continuously three time, it will increase a rotary speed of a fan 25 by 5% and again detect the harmful gas component produced by incomplete combustion at an interval of time 2t. For example, when an intake port of the fan 25 is sharply clogged by a foreign matter, even if an attempt is made to increase the rotary speed of the fan 25, it will be impossible to eliminate incomplete combustion. In this case, the harmful gas compo nent whose density is higher than the specified density is detected continuously three times. Therefore, it is necessary to indicate combustion failure with a buzzer or the like and stop every control operation by closing respective solenoid valves 22 to 24 and carrying out after purging for a specified time.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a safety device for a gas combustor that uses a gas sensor to prevent incomplete combustion.

(Prior art) A gas combustor includes a case with a gas burner inside,
A fan that supplies combustion air into the case in an amount corresponding to the amount of gas supplied to the gas burner, and a gas sensor that is installed in the combustion gas passage downstream of the gas burner and detects harmful gas components caused by incomplete combustion. If the concentration of harmful gas components (e.g. CO) resulting from incomplete combustion exceeds a predetermined limit, a gas sensor detects this and stops the gas supply to the gas burner, thereby stopping the gas combustor. There is something I did. This type of incomplete combustion occurs when the amount of combustion air is reduced due to clogging of the fins of the heat converter installed inside the case or the exhaust stack due to combustion products, or partial blockage of the intake port due to foreign matter. There are many.

(Problem to be Solved by the Invention) However, the CO concentration in the combustion gas changes due to various external conditions in addition to the causes mentioned above. Since the back pressure inside the cylinder increases and the amount of combustion air supplied by the fan decreases, the CO concentration temporarily exceeds the limit, causing the inconvenience of stopping the gas combustor.

The present invention temporarily compensates for the lack of air by increasing the rotational speed of the fan when the lack of combustion air is slight, but only when the concentration of harmful gas components such as CO exceeds the limit, does the The purpose is to eliminate the above-mentioned inconvenience by stopping the combustor.

(Means for Solving the Problems) To this end, the safety device for a gas combustor according to the present invention, as illustrated in the attached drawings, includes a case 10 in which a gas burner 20 is provided, and a gas supply for the gas burner 20/\. a fan 25 that supplies combustion air into the case 10 in an amount corresponding to the amount of combustion air; a scum sensor 36 that is installed in the combustion gas passage downstream of the gas burner 20 and detects harmful gas components caused by incomplete combustion; , a safety device for a gas combustor including a control device 30 that stops gas supply to the gas burner 20 if the gas sensor detects the harmful gas component at a predetermined concentration or higher; When detecting the harmful gas component at a concentration higher than a predetermined concentration, first increase the rotation speed of the fan 36 without stopping the gas supply to the gas burner 20, and then use the gas sensor 36 to detect the harmful gas component at a predetermined concentration or higher. When the gas burner 20 is detected
This is characterized by stopping the gas supply to.

The control device 30 increases the rotational speed of the fan and controls the supply of gas to the gas burner when the gas sensor 36 detects a predetermined concentration or more of the gas component continuously at a predetermined time interval. It is desirable to perform a stop.

Further, the control device 30 controls the fan 25 when the gas sensor 36 detects the harmful gas component having a predetermined concentration or more.
An abnormality display may also be displayed when the rotation speed of the motor is increased. Further, the control device 30 repeats the operation of increasing the rotational speed of the fan 25 without stopping the gas supply to the gas burner 20 when the gas sensor 36 detects the harmful gas component having a predetermined concentration or higher. It may also be done by

(Function) If the gas sensor 36 detects harmful gas components due to incomplete combustion of a predetermined concentration or higher during operation of the gas combustor, the control device 30 increases the rotational speed of the fan 25 to compensate for the decrease in the amount of combustion air. After that, the gas sensor 36 detects harmful gas components, and if the concentration falls below a predetermined concentration, the operation of the gas combustor continues, and if the concentration does not fall below a predetermined concentration, the gas supply is stopped and the gas combustor is stopped. The rotational speed of the fan 25 may be increased and the gas combustor may be stopped when a harmful gas component of a predetermined concentration or higher is detected several times in succession after a predetermined period of time. Further, an abnormality display may be displayed at the same time as the rotational speed of the fan 25 increases.
Furthermore, compensation for the decrease in the amount of combustion air may be performed again by increasing the rotational speed of the fan 25, and the gas combustor may be stopped if the concentration of harmful gas components does not fall below a predetermined concentration.

(Effects of the Invention) As described above, according to the present invention, when the deficiency in the amount of combustion air is slight, the rotation speed of the fan is increased to compensate for the deficiency in the amount of combustion air and the gas combustor is operated. This eliminates the inconvenience of stopping the gas combustor every time there is occasional and slight incomplete combustion. If the fan rotation speed is increased and the gas combustor is stopped when a harmful gas component of F is detected several times in a row, the safety device may be activated even though it is not necessary due to noise from some reason. It will no longer work. Further, by displaying an abnormality display, it is possible to inform the user that a slight abnormality has occurred, although it does not affect the use of the device for the time being.

(Example) The present invention will be explained below using examples shown in the accompanying drawings.

As shown in FIG. 1, a gas burner 20 is provided in the lower part of the case 10 that forms the combustion chamber of the instantaneous water heater, and a solenoid valve 22, a proportional solenoid valve 24, and Fuel gas is supplied by a gas supply path 21 having a main electromagnetic valve 23, and combustion air is supplied by an electric fan 25 provided on the lower side of the case 10. The original 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 degree continuously according to the control current to change the amount of gas supplied to the gas burner 20. be. Further, the fan 25 has a rotating speed that continuously changes and supplies an amount of combustion air corresponding to the amount of gas supplied.

A water flow sensor 37 is provided in 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 water temperature sensor is provided in the hot water supply pipe 17 connected to the outlet side. 38 and a hot water tap 18 are provided. The water supplied from the water supply pipe 16 is heated by the gas burner 20 when passing through the heat exchanger 15, reaches a predetermined temperature, and is discharged from the hot water tap 18. The upper part of the case 10 above the heat exchanger 15 is connected to the exhaust pipe 12 through the hood 11, and inside the case 10 immediately above the gas burner 20 is a flame sensor such as a flame rod that detects the presence or absence of a flame in the gas burner 20. A gas sensor 36 is provided in the hood 11 to detect harmful gases (Co, H, C, etc.) caused by incomplete combustion.

The electronic control unit 30 that controls the operation of the instantaneous water heater is composed of a central processing unit (CPU), a read-only memory (ROM), a writable memory (RAM), and an interface. As shown in FIG.
, a flame sensor 35, a gas sensor 36, a water flow sensor 37, and a hot water temperature sensor 38. The ROM of the electronic control device 30 stores a control program and constants necessary for controlling the operation of the instantaneous water heater, and the RA'M stores variables such as the number of detections n, which will be described later.

Further, the operating device 31 is provided with various switches, a hot water temperature setting device, various display lamps, etc. necessary for operating the instantaneous water heater. The CPU of the electronic control device 30 inputs signals from the operating device 31 and the sensors 35 to 38, etc. according to the control program, performs predetermined calculations, and operates the solenoid valves 22 to 24.
, the fan 25, the operating device 31, etc., 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, and the operation of this embodiment will be explained using these flowcharts.

FIG. 2 is a flowchart of the main program. When the electronic control device 30 is powered on and activated by an operation switch (not shown), the CPU resets each variable to 0 or a predetermined initial value and starts control operations based on this main program. . First step 1
At 00, the CPU detects water supply pipe 16 by water flow sensor 37.
Detects the presence or absence of water flow passing through. If the hot water tap 18 is closed and no water flow is detected, the control operation will not proceed.
8 is opened and water flow exceeding a predetermined minimum amount is detected, the process proceeds to step 101, where the CPU opens the original solenoid valve 22 and the main solenoid valve 23, sets the proportional solenoid valve 24 to a predetermined ignition opening degree, and
The fan 25 is operated at a predetermined ignition rotation speed, the ignition device (not shown) is operated for a predetermined time, and the gas burner 20
ignite the gas spewing out. Next, in step 102, the CPLJ sets 1=0 and starts measuring time t using a built-in clock pulse generator, and steps 103 to 105 are repeated while the hot water tap 18 is opened. In step 103, the CPU detects harmful gas components such as CO in the combustion gas using the gas sensor 36 as described later, and if the detected concentration exceeds a predetermined concentration, the CPU first increases the rotation speed of the fan 25, and even if the detected harmful components If the concentration does not fall below a predetermined level, the operation of the gas combustor is stopped. If the concentration is below the predetermined concentration, the control operation proceeds to the next step 104, where the CPU compares the hot water temperature detected by the hot water temperature sensor 38 with the hot water temperature set by the operator 31, and adjusts the hot water temperature so that the hot water temperature becomes the set temperature. The opening degree of the proportional solenoid valve 24 is controlled to control the amount of gas supplied to the gas burner 20, and the rotational speed of the fan 25 is controlled to control the amount of combustion air so that a predetermined air-fuel ratio is obtained.

If the hot water tap 18 is closed, the control operation proceeds from step 105 to step 106, and the original solenoid valve 22 and the main solenoid valve 2 are closed.
One of the solenoid valves 22 and 23 is closed after a predetermined time delay than the other, and the operation of both electromagnetic valves 22 and 23 is checked by the flame sensor 35. If an abnormality in the operation of both electromagnetic valves 22 and 23 is detected, the CPU stops the operation of the gas combustor, and if no abnormality is detected, 1=0 in step 107.
A built-in clock pulse generator starts measuring time t, and in step 108, the fan 25 is set to a predetermined purge rotation speed and a boss purge is started. Until this time t reaches a predetermined boss purge time tl (for example, 5 minutes), the CPU repeats steps 109 and 110, and checks for a small amount of gas leakage that cannot be detected in step 106. Gas leakage is not detected (t>t
l, the CPU turns on fan 2 in step 111.
5 is stopped to complete the boss purge, and the control operation returns to step 100. Thereafter, the above operation is repeated every time the hot water tap 18 is opened. The electromagnetic valve operation check in step 106 and the gas leakage check in step 109 are not directly related to the present invention, so their details will be omitted.

Next, details of the operation of the incomplete combustion check in step 103 will be explained with reference to the flowchart of FIG. In steps 200 to 204, the CPU detects harmful gas components such as CO due to incomplete combustion with the gas sensor 36 every time t2 (for example, 1 minute), and no harmful gas components with a predetermined concentration or higher are detected three times in a row. As long as this is the case, the control operation constantly returns to step 104 in FIG. 2 and repeats the normal combustion control. If the number of detections of a harmful gas component having a predetermined concentration or higher is two or less, the number of detections n is reset to O in step 213 each time. If a harmful gas component with a predetermined concentration or higher is detected three times in a row, the CPU advances the control operation from step 204 to step 210. When the process proceeds to step 210 for the first time, flag F is O, so CP
The LI advances the control operation to steps 211 to 213, increases the rotation speed of the fan 25 by 5%, changes the flag F to 1, and
The number of detections n is reset to 0 and the control operation returns to step 104 in FIG. In step 211, an abnormality may be indicated by blinking a combustion lamp or the like.

Then, in steps 200 to 204, the CPU detects harmful gas components due to incomplete combustion again at every time t2.

Incomplete combustion usually occurs when the fins of the heat exchanger 15 or the exhaust stack 1
This occurs when the amount of combustion air from the fan 25 decreases due to reasons such as the combustion passage being clogged with combustion products, or strong winds hitting the vicinity of the exhaust port to the outside and increasing the back pressure in the combustion passage. In these cases, since the degree of decrease in the amount of combustion air is small, the incomplete combustion can be resolved by increasing the rotational speed of the fan 25 by 5% to compensate for the decrease in the amount of combustion air. As a result, no harmful gas components having a predetermined concentration or more due to incomplete combustion are detected in step 202, so the control operation returns from step 202 to step 213 to step 104. After this, 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 will always be increased by 5%, and the control operation will continue from step 202 to step 213. Returning to step 104, the instantaneous water heater is activated.

However, if the wind hitting the vicinity of the exhaust port is extremely strong or if the intake port of the fan 25 is significantly blocked by foreign matter, incomplete combustion will not be resolved even if the rotational speed of the fan 25 is increased by 5%. In this case, since harmful gas components having a predetermined concentration or higher are detected three times in a row again in step 202, the control operation is performed in step 2.
Proceed to step 10. In this case, since the flag F is 1, the CPU advances the control operation to step 214, displays an abnormality using an indicator lamp or buzzer, etc., and each solenoid valve 22 to
24 is closed, and after-purging is performed for a predetermined time (for example, 10 seconds) by the fan 25, and all control operations are stopped.

According to the above embodiment, if the shortage of combustion air is slight, the rotational speed of the fan 25 is increased to compensate for the shortage of combustion air and continue operation of the instantaneous water heater. Therefore, the inconvenience of the instantaneous water heater stopping due to temporary causes such as strong wind hitting the exhaust port is eliminated.

In this case, if the abnormality is displayed at the same time as the fan rotation speed increases in step 211, the user will be able to know that a slight abnormality has occurred, although there is no problem with using it for the time being. If such an abnormality continues, it can be determined that the fins of the heat exchanger 15 or the exhaust pipe 12 are clogged and need to be cleaned.

In the embodiments shown in FIGS. 2 and 3, the fan rotation speed is increased only once, but it may be increased twice. In that case, step 214 in FIG. The flowchart in Figure 4 (steps 210 to 3 in Figure 3)
214).

Furthermore, the present invention is not limited to instantaneous gas water heaters, but can also be used in other gas combustors.

[Brief explanation of the drawing]

Figures 1 to 3 show an embodiment of the safety device for a gas combustor according to the present invention, with Figure 1 being an overall explanatory diagram of the structure, Figure 2 being a flowchart of the main program, and Figure 3 being incomplete combustion. 12 is a flowchart of a check subprogram. FIG. 4 is a flowchart showing the changed parts of the subprogram in the modified embodiment. Explanation of symbols 10... Case, 20... Gas burner, 25... Fan, 30... Control device (electronic control device), 36...
gas sensor.

Claims (1)

[Scope of Claims] (1) A case including a gas burner therein, a fan that supplies combustion air into the case in an amount corresponding to the amount of gas supplied to the gas burner, and a fan located downstream of the gas burner. A gas sensor provided in a combustion gas passage to detect harmful gas components due to incomplete combustion, and a control device that stops gas supply to the gas burner if the gas sensor detects the harmful gas components at a predetermined concentration or higher. In the safety device for a gas combustor, when the gas sensor detects the harmful gas component at a predetermined concentration or higher, the control device first increases the rotation speed of the fan without stopping the gas supply to the gas burner, and then increases the rotation speed of the fan without stopping the gas supply to the gas burner. A safety device for a gas combustor, wherein gas supply to the gas burner is stopped when the gas sensor detects the harmful gas component at a predetermined concentration or higher. (2) The control device increases the rotational speed of the fan and controls the gas supply to the gas burner when the gas sensor detects the harmful gas component at a predetermined concentration or higher a plurality of times in succession after a predetermined period of time. The safety device for a gas combustor according to claim 1, wherein the safety device is configured to shut down the gas combustor. (3) The control device also displays an abnormality display when the gas sensor detects the harmful gas component at a predetermined concentration or higher and increases the rotational speed of the fan. Combustor safety device. (2) The control device is configured to detect the harmful gas component with a predetermined concentration or higher using the gas sensor and repeatedly increase the rotational speed of the fan without stopping the gas supply to the gas burner. The safety device for a gas combustor according to claim 1.