JP2000121047A - Controller for combustor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress production of hazardous gas or odor by suppressing yellow combustion immediately after firing even when a combustor is used in high land or when it is used with dust adhering to the combustion air supply path. SOLUTION: A combustion control section 7 for controlling combustion through a combustion air supply means 3 and a fuel supply means 2 comprises a section 7a for setting the air fuel ratio at the time of firing at a value different from the air fuel ratio during normal combustion, and means 7c for altering the air fuel ratio at the air fuel ratio setting section 7a from a first firing time air fuel ratio to a second firing time air fuel ratio lower than the air fuel ration during normal combustion upon provision of a firing detection signal.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a control device for a combustion appliance such as a hot air heater.

[0002]

2. Description of the Related Art Conventionally, in a burning appliance such as a warm air heater,
During normal combustion, in order to suppress harmful exhaust gas during combustion, the amounts of combustion air and fuel are controlled so as to maintain an optimal combustion state. In the case of such a burning appliance,
At the optimal air-fuel ratio during normal combustion (air-fuel ratio), the fuel tends to lift when ignited, resulting in poor ignitability. As a countermeasure, lower the air-fuel ratio only during ignition, and Some are controlled to shift to normal combustion.

[0003] Further, as in a control apparatus for a combustion appliance disclosed in Japanese Patent Publication No. Hei 6-29669, a plurality of ignition air / combustion amount setting units are provided which are set to air-fuel ratios different from those in normal combustion. At the start of operation or during a predetermined time after the start of operation, based on a signal obtained from a temperature detection device that detects the temperature of the combustion section, any one of the ignition-time air amount
There is one that selects the combustion amount setting. In the case of this device, the ignition is performed by selecting the optimum air-fuel ratio according to the temperature of the combustion part at the time of ignition, so that not only the temperature of the combustion part is cooled but also the case where the temperature of the combustion part at the time of re-ignition is high. Also, optimum ignition conditions can be obtained, and under normal conditions, no unburned gas is generated at the time of ignition and yellow combustion does not occur.

However, in the above-described conventional configuration, the air-fuel ratio at the time of ignition is lowered in advance in order to improve the ignitability in a normal use state. If the product is used in a state where dust or the like has adhered to the air supply passage for combustion and the amount of air has decreased,
The air-fuel ratio at the time of ignition is further reduced, and ignition occurs by yellow combustion. Normally, ignition is detected based on the magnitude of the flame current flowing through the flame.However, when ignited by yellow combustion, the ignition current cannot be detected because the flame current is small, and the safety device operates to stop the ignition operation. As a result, combustion cannot be continued.

[0005] Further, even when ignition is detected, the air-fuel ratio does not reach the normal combustion until a predetermined time has elapsed, and during this time, yellow combustion is continued to emit harmful gas and generate odor. There was a problem.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and is not limited to a normal use state.
It is an object of the present invention to obtain a control device for a combustion appliance that can reliably detect ignition and suppress yellow combustion after detection of ignition even when used at high altitudes or when dust adheres to a combustion air supply path. .

[0007]

According to the present invention, there is provided a control apparatus for a combustion apparatus, comprising: a combustion section, fuel supply means for supplying fuel to the combustion section, and combustion air supply for supplying combustion air to the combustion section. Means, a combustion control unit that controls the combustion air supply unit and the fuel supply unit to perform combustion, and an ignition detection unit that outputs an ignition detection signal when a flame is formed in the combustion unit, The combustion control unit, an air-fuel ratio setting unit that sets the air-fuel ratio at the time of ignition to a value different from the air-fuel ratio during normal combustion, and at the time of the ignition of the air-fuel ratio setting unit at the time when the ignition detection signal is input. It is provided with ignition air-fuel ratio changing means for changing the air-fuel ratio.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiment 1 Hereinafter, Embodiment 1 of the present invention will be described with reference to the block diagram of the control device of FIG. 1 and the configuration diagram of FIG. 1 and 2, reference numeral 1 denotes a combustion unit, 2 denotes an electromagnetic pump as fuel supply means for supplying fuel to the combustion unit 1, and 3 denotes combustion air supply means for supplying combustion air to the combustion unit 1. Reference numeral 4 denotes an igniter as ignition means, and reference numeral 5 denotes a frame rod as ignition detection means for detecting a flame current flowing through the flame 6.

Reference numeral 7 denotes the electromagnetic pump 2, a combustion blower 3,
An air-fuel ratio setting unit 7a that controls the electromagnetic pump 2 and the combustion blower 3 by controlling the igniter 4 and the like and performing combustion by setting the ratio of the amount of combustion air to the amount of combustion;
A timer section 7b that starts counting at the same time as starting the ignition operation; and an ignition section that changes the air-fuel ratio at the time of ignition of the air-fuel ratio setting section 7a by the earlier signal of the signal from the timer section 7b and the signal from the frame rod 5. It has an air-fuel ratio changing means 7c and the like, and starts operation by the operation switch 8. The combustion unit 1 includes a burner head 1a for forming a flame 6 and a vaporizing unit 1b for vaporizing liquid fuel.
And a heater 1c for heating the vaporizing section 1b.

FIG. 3 is an electric circuit diagram of the control device.
In FIG. 3, reference numeral 9 denotes a commercial power supply, and 7 denotes a combustion control unit including a microcomputer or the like. The combustion control unit 7 includes a relay coil 10a of a relay contact 10b for turning on / off the power supply to the heater 1c and a power supply to the igniter 4. A solid state relay (hereinafter referred to as SSR) comprising a relay coil 11a of a relay contact 11b for turning on / off the power supply, a light emitting element 12a for controlling the phase of the combustion fan 3 and a phototriac 12b.
12), and a driver 13 for driving the electromagnetic pump 2 is connected. Further, signals of the operation switch 8 and the frame rod 5 are input to the combustion control unit 7.

Next, the operation of the above configuration will be described with reference to the control flowchart of FIG. First, when the operation switch 8 is turned on (step 20), the combustion control unit 7 energizes the relay coil 10a to close the relay contact 10b, and energizes the heater 1c to start preheating the vaporizing unit 1b (step 21). When the preheating is completed, the first ignition air-fuel ratio is set by the air-fuel ratio setting unit 7a in the combustion control unit 7 (step 22), and the SSR 12 is energized so that the air-fuel ratio becomes the set air-fuel ratio. Is rotated (step 23) to start pre-purge.

By changing the phase angle of the SSR 12, the combustion blower 3 is controlled so as to have a set rotation speed. Usually, the air-fuel ratio at the time of ignition is set slightly smaller than the air-fuel ratio at the time of normal combustion in order to improve the ignitability. For example, if the combustion amount is set to 2500 Kcal / h and the rotation speed of the combustion blower 3 is set to 1900 rpm during normal combustion, only the rotation speed of the combustion blower 3 is set to 1800 rpm during ignition. Also, the combustion blower 3
It is also possible to change only the combustion amount while keeping the rotation speed of.

When the pre-purge is completed (Step 2)
4), energizing the relay coil 11a and relay contact 11b
Is closed, the igniter 4 is turned on, the electromagnetic pump 2 is turned on via the driver 13, and at the same time, the timer section 7b in the combustion control section 7 starts counting (step 25). When the electromagnetic pump 2 is turned on and liquid fuel such as kerosene is supplied to the vaporizing section 1b, it becomes a vaporized gas due to high temperature, and when the vaporized gas reaches the burner head 1a,
It is ignited by the spark of the igniter 4. When the flame 6 is formed, a flame current flows from the frame rod 5 to the burner head 1a. The magnitude of the flame current varies depending on the air-fuel ratio, and becomes smaller during yellow combustion or lift combustion than in the optimum combustion state.

When the flame current exceeds a predetermined value, the combustion controller 7 detects ignition (step 26), and the relay coil 11a
Is stopped and the igniter 4 is turned off (step 2).
7). When the ignition is detected, a signal is sent from the ignition air-fuel ratio changing means 7c in the combustion control unit 7 to the air-fuel ratio setting unit 7a, and the signal is set to the second ignition air-fuel ratio (step 28).
12, the phase control is performed to change the set rotation speed of the combustion blower 3 (step 29), for example, from 1800 rpm to 1
It is changed to 850 rpm.

When the count value of the timer section 7b has passed for 30 seconds (step 30), the air-fuel ratio setting section 7a is changed to the set value for normal combustion (step 31), and the set rotation speed of the combustion fan 3 is increased from 1850 rpm. It is changed to 1900 rpm. As described above, since the air-fuel ratio at the time of normal combustion is not immediately set to the air-fuel ratio at the time of the normal combustion immediately after ignition, the fuel is burned for a while at the second air-fuel ratio at the time of ignition. Even when the fuel is burned at a low fuel ratio, the generation of yellow combustion at the time of changing the rotation speed can be suppressed by gradually increasing the air-fuel ratio, and the generation of harmful gas and odor can be reduced.

Next, for example, when used at high altitudes or when dust or the like adheres to the combustion air supply path, the density and amount of air are reduced, so that yellow combustion occurs and the flame current does not reach a predetermined value. Sometimes. At this time, if ignition is not detected even if the timer started with the ignition operation has elapsed for 5 seconds (step 32), a signal is sent from the timer unit 7b to the ignition-time air-fuel ratio changing unit 7c, and the value of the air-fuel ratio setting unit 7a is changed to the first value. 2 is set to the air-fuel ratio at the time of ignition (step 33), and the set rotation speed of the combustion blower 3 is increased from 1800 rpm to 1850.
rpm (step 24).

When the number of revolutions of the combustion blower 3 increases, the state of air shortage is eliminated, the combustion state becomes an optimal state, the flame current becomes a predetermined value or more, and ignition detection becomes possible. When ignition is detected, the process proceeds to step 27 similarly to the above flow,
Since steps 28 and 29 have already been performed, the process proceeds to steps 30 and 31.

As described above, in the first embodiment,
Not only in normal use, but also in high altitude use and when the amount of air supply is slightly low due to dust adhering to the combustion air supply path, if ignition does not occur, change the air-fuel ratio and ignite in the optimal combustion state Therefore, the yellow combustion continues without emitting harmful gas or generating odor,
It can be detected reliably.

Embodiment 2 In the first embodiment, when the ignition is not detected, the ignition air-fuel ratio is changed only once. However, as shown in a control flowchart of FIG. 5, the ignition air-fuel ratio is sequentially changed until the ignition is detected. You may do it. In FIG. 5, steps 20 to 31 are the same as those in FIG. If the ignition is not detected, every time the timer becomes a multiple of 5 (step 35),
That is, after 5, 10, 15,... Seconds, the process proceeds to steps 36 and 37, in which the air-fuel ratio at the time of ignition of the air-fuel ratio setting section 7a is changed, and the rotation speed of the combustion fan 3 is increased by 50 rpm. With this, the air-fuel ratio is considerably low at the time of ignition, and even if ignition occurs in the red fire state, the ignition air-fuel ratio is gradually changed until the optimal combustion state where the flame current rises, so it is possible to reliably detect ignition After the ignition, the air-fuel ratio at the time of the normal combustion is not immediately set, and the fuel is burned for a while at the second air-fuel ratio at the time of the ignition. Even when the fuel is burned at a lower speed, the generation of yellow combustion when the rotation speed is changed can be suppressed, and the generation of harmful gas and odor can be reduced.

[0020]

As described above, according to the present invention, the air-fuel ratio setting unit for setting the air-fuel ratio at the time of ignition to a value different from the air-fuel ratio during normal combustion, and the air-fuel ratio at the time when the ignition detection signal is inputted, An ignition air-fuel ratio changing means for changing the air-fuel ratio of the fuel ratio setting unit from the first ignition air-fuel ratio to a second ignition air-fuel ratio lower than the air-fuel ratio during normal combustion is provided. Since the fuel is burned at the second ignition air-fuel ratio for a while without setting the fuel ratio, the combustion part 1 and the temperature of the vaporized gas are low immediately after ignition. The generation of yellow combustion can be suppressed, and the generation of harmful gases and odors can be reduced.

[Brief description of the drawings]

FIG. 1 is a block diagram of a control device for a combustion apparatus according to Embodiment 1 of the present invention.

FIG. 2 is a configuration diagram of a combustion device according to Embodiment 1 of the present invention.

FIG. 3 is an electric circuit diagram of the control device according to the first embodiment of the present invention.

FIG. 4 is a control flowchart of a control device according to the first embodiment of the present invention.

FIG. 5 is a control flowchart of a control device according to Embodiment 2 of the present invention.

[Explanation of symbols]

1 combustion unit, 2 fuel supply means (electromagnetic pump), 3 combustion air supply means (combustion blower), 5 ignition detection means (flame rod), 7 combustion control unit, 7a air-fuel ratio setting unit, 7c air-fuel ratio change at ignition means.

Claims (1)

[Claims] 1. A combustion section, fuel supply means for supplying fuel to the combustion section, combustion air supply means for supplying combustion air to the combustion section, combustion air supply means and the fuel supply means And a combustion detection unit that outputs an ignition detection signal when a flame is formed in the combustion unit, and the combustion control unit determines the air-fuel ratio at the time of ignition by normal combustion. An air-fuel ratio setting unit that sets the air-fuel ratio to a value different from the medium air-fuel ratio; and an ignition air-fuel ratio changing unit that changes the air-fuel ratio at the time of ignition of the air-fuel ratio setting unit when the ignition detection signal is input. A control device for a combustion appliance, characterized in that: