JP2684817B2 - Ignition control device for gas combustion equipment - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an ignition control device used in a forced combustion exhaust gas combustion device such as a water heater.

[Prior Art] In this type of gas combustion equipment, as a ignition sequence at the start of combustion, a fan is operated for a certain period of time before ignition, and fuel gas remaining in the combustion chamber is discharged (pre-purge) to prevent an explosion. Is being done. In the case of a water heater, even after the combustion was stopped, the fan operation was continued for several minutes to maintain the air supply to the combustion chamber (post-purge), and the combustion request was made again during the post-purge. In this case, an ignition control is also carried out so as to prevent the drop of the hot water temperature by immediately performing the ignition operation (for example, see Japanese Patent Publication No. 63-27611).

[Problems to be Solved by the Invention] By the way, in the air purge, the residual gas in the combustion chamber is actively replaced with fan air before and after combustion. However, the phenomenon in which the fuel gas remains is only in the combustion chamber. However, it also occurs inside the nozzle holder of the gas nozzle that supplies the fuel gas to the combustion chamber. That is, immediately after the combustion is stopped, the gas passage from the gas valve to the gas nozzle is filled with the fuel gas, and the fuel gas is gradually replaced with the air in the combustion chamber over time. Then, in the process of being replaced with the air, the fuel gas and the air are mixed at an appropriate ratio inside the nozzle holder or the like in a certain time period after the combustion is stopped. However, if an ignition operation is performed to restart combustion in the combustion chamber at this time, a so-called ignition back phenomenon (hereinafter, simply referred to as flashback) that occurs in a mixed gas having a high combustion speed occurs, and ignition mistakes frequently occur.

Moreover, it is experienced that such a problem of deterioration of combustibility is likely to occur within the set time of the post-purge for which immediate ignition is required (for example, 2 minutes after the combustion is stopped).

In view of the above-mentioned problems, the present invention provides an ignition control device that does not suffer deterioration of combustibility due to flashback even when ignition is performed and combustion is restarted at any timing after the combustion is stopped.

[Means for Solving the Problems] The present invention provides a combustion chamber in which a combustion pipe is provided, a gas nozzle for supplying fuel gas to the combustion pipe of the combustion chamber from a gas pipe through a noise holder, and a gas nozzle from the gas nozzle. In an ignition control device for a gas combustion device, which includes a gas valve for switching supply or stop of fuel, a supply / exhaust fan for supplying combustion air to the combustion chamber, and an ignition device for igniting an air mixed gas in the combustion chamber, When restarting combustion after stopping combustion in the combustion chamber, the delay time t = F determined based on the elapsed time pressure T after the combustion is stopped after opening the gas valve.
(T), and an ignition delay means for performing an ignition operation by the ignition device.

[Operation] If the ignition delay means is provided, the gas valve is opened prior to ignition in the combustion chamber when combustion is restarted,
Residual gas remaining in the gas passage downstream of the gas valve is purged by the fuel gas. Therefore, even if air is mixed with the residual gas in the temporary nozzle holder or the like at a high burning rate, there is no danger of causing a flashback.

Example An example of the present invention will be described with reference to the drawings.

FIG. 1 shows the configuration of a forced-exhaust type gas combustion apparatus according to the present invention in the specification of a water heater.

In this gas combustion device, a combustion chamber 1 in which a combustion tube 2 is installed
And the gas pipe 3 to the nozzle holder 5 in the combustion pipe 2 of the combustion chamber 1.
A gas nozzle 4 for supplying a fuel gas through a combustion chamber 1
A supply / exhaust fan 6 that is provided at the bottom of the combustion pipe 2 and supplies combustion air to the inside and outside of the combustion tube 2, and an ignition device 7 (igniter 8 and spark plug 9) that ignites the air-mixed gas in the combustion chamber 1.
Are provided. Reference numeral 10 denotes a gas solenoid valve provided in the middle of the gas pipe 3. Further, 11 is a heat exchanger arranged above the combustion chamber 1, through which a hot water supply pipe 12 is passed. Reference numeral 13 indicates an exhaust port.

The gas combustion equipment includes a controller composed of a microcomputer for controlling the operation of the water heater.
20 are provided. The controller 20 outputs an operation signal, and the fan 6, based on a command based on the operation signal,
Each operating state of the gas valve 10 and the ignition device 7 (igniter 8) is switched to ON / OFF. The controller 20 is
By inputting a switch signal from a running water switch (not shown) provided in the hot water supply pipe 12, the operation signal is switched ON / OFF in synchronization with the switching of the switch signal.

In this ignition control device, the fan 6 and the gas valve 10 are operated and stopped in synchronization with the switching of the operation signal from the controller 20 and the gas valve 10 is opened and closed. While the ignition device 7 is switched by the ignition delay means 21 incorporated in the controller 20, when the operation signal is switched to ON, that is, when the combustion chamber 1 is requested to restart combustion, the igniter 8 is switched.
The output timing of the ON switching signal to is delayed, so that the ignition timing by the spark plug 9 is delayed.

The ignition delay means 21 has a built-in timer and delays the output timing of the ON switching signal by the time set by the timer, stores a preferable variable pattern of the timer set time in advance, and sets the ignition timing by the ignition plug 9. It has a function to delay according to the elapsed time from the stop of combustion to the restart of combustion.

FIG. 3 shows an example of a variable pattern of the timer set time. Here, the delay time t of ignition by the ignition device 7 is a function of the elapsed time T from the end of combustion; t
= F (T). That is, the delay time t is a constant time immediately after the combustion is stopped (T = 0) when the inside of the nozzle holder 5 or the like is filled with the fuel gas, and the inside of the nozzle holder 5 or the like is completely replaced with air. After elapse (T ≧ T _L )
In, there is no danger of flashback, so t = 0 is set. On the other hand, in the time zone of T; 0 to _TL in which the interior of the nozzle holder 5 and the like is partially replaced with air, it corresponds to the elapsed time T after the combustion is stopped, that is, to correspond to the mixing ratio of air. Thus, the delay time t = F (T) required to prevent flashback is set.

The operation of the ignition control device will be described with reference to the timing chart shown in FIG.

According to this device, when hot water is supplied when the operation signal of the controller 20 is set to ON, the fan 6, the gas valve 10 and the igniter 8 are all set to ON, and combustion in the combustion chamber 1 is continued. When the operation signal is switched to OFF from this state, the gas valve 10 and the igniter 8 are switched to the operation state OFF, the supply of the fuel gas from the gas nozzle 4 is stopped, and the combustion in the combustion chamber 1 is stopped. At this time, the fan 6 is kept under load for a certain period of time to post-purge the combustion chamber 1. Next, when the operation signal is turned on again during the post-purge, that is, when the combustion request is made again within a short time after the combustion is stopped, the gas valve 10 and the fan 6 are immediately turned on. , Igniter 8
With respect to, the ignition delay means 21 is switched to the operation ON state after delaying by a predetermined delay time t ₁ {= F (T ₁ )}, t ₂ {= F (T ₂ )}. .

That is, since the ignition delay means 21 is provided, when the combustion is restarted, the gas valve 10 is opened at the same time as the operation of the fan 6 is started and the gas on the downstream side of the gas valve is opened prior to the ignition by the spark plug 9 in the combustion chamber 1. The residual gas remaining in the passage will be purged by the fuel gas. For this reason, even if air is mixed with the residual gas in the provisional nozzle holder 5 or the like at a high burning rate, it is ignited after being discharged, so there is no risk of flashback.

Moreover, since the timing t of the delayed ignition is set according to the elapsed time T after the combustion is stopped as described above, the required delay time can be changed according to the air replacement ratio expected inside the nozzle holder 5 or the like. It can be set, and further, for example, immediately after the combustion is stopped when the combustion gas is filled in the gas passage,
On the contrary, it is possible to cancel the delay substantially when the flashback countermeasure is unnecessary, such as after a long time ( _TL ) when the gas passage is completely replaced with air, so immediate ignition is required. The ignition delay time during post-purge can be shortened to the necessary minimum.

[Advantages of the Invention] As described above, according to the present invention, the ignition delay means for delaying the ignition timing by the ignition device in the combustion chamber at the time of restarting combustion is provided, and the residual gas remaining in the gas passage is converted into the fuel gas. Since the ignition is performed after purging, even if the combustion is restarted at any timing after the combustion is stopped, the flashback does not occur, and good combustibility can be secured. Further, since the ignition timing is delayed according to the elapsed time after the combustion is stopped, the delay time required for the flashback countermeasure can be suppressed to the necessary minimum.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of a gas combustion device according to an embodiment of the present invention, FIG. 2 is a timing chart showing the operation thereof, and FIG. 3 is a diagram showing an example of a variable pattern of a timer set time set in ignition delay means. Is. 1 ... Combustion chamber, 2 ... Combustion tube, 3 ... Gas tube, 4 ... Gas nozzle, 5 ... Nozzle holder, 6 ... Fan, 7 ...
Ignition device, 8 ... Igniter, 9 ... Spark plug, 10 ...
… Gas valve, 11 …… Heat exchanger, 12 …… Hot water supply pipe, 13 ……
Exhaust port, 20 ... Controller, 21 ... Ignition delay means.

Claims (1)

(57) [Claims] 1. A combustion chamber having a combustion pipe therein, a gas nozzle for supplying fuel gas to the combustion pipe of the combustion chamber from a gas pipe through a noise holder, and a gas for switching supply or stop of fuel from the gas nozzle. In the ignition control device of the gas combustion device, which includes a valve, a supply / exhaust fan that supplies combustion air to the combustion chamber, and an ignition device that ignites an air-mixed gas in the combustion chamber, after stopping combustion in the combustion chamber, When resuming combustion, after opening the gas valve, ignition delay means for performing an ignition operation by the ignition device with a delay time t = F (T) determined based on an elapsed time T after the combustion is stopped, An ignition control device for a gas combustion device, comprising: