JP2853466B2 - Combustor control device - Google Patents

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 combustor for igniting and burning a vaporized gas using an ignition heater.

[0002]

2. Description of the Related Art Conventionally, there is a combustor of this type shown in FIG. In the figure, 1 is an oil tank, 2 is a sub-tank for storing kerosene supplied from the oil tank 1, 3 is an oil feed pipe, 4 is a constant oil leveler, and 5 is an electromagnetic pump for pumping kerosene to the constant oil leveler 4. , 6 is a combustion blower, 7 is a duct for guiding the blast from the combustion blower 6 to the primary air supply port 8, 9 is a pressurized pipe which branches off from the duct 7 and guides a part of the blast to the constant oil level unit 4, 10. Is a pressurizing solenoid for controlling the air flow to the pressurizing pipe 9, 11 is a pipe orifice for supplying kerosene to the vaporizer 12 when the oil level of the constant oil leveler 4 is pressurized, and 13 is a vaporizer 12 , A vaporizer thermistor 14 for detecting the temperature of the vaporizer 12, 15 an ignition heater for igniting the vaporized gas vaporized by the vaporizer 12, 16 a burner head as a combustion unit, and 17 a flame. Detects flame current (ion current) flowing through Flame rod as flame detection means for monitoring the combustion state by Rukoto,
Reference numeral 18 denotes a combustion tube, and 19 denotes a convection blower for blowing out high-temperature gas as warm air to the outside of the apparatus main body.

Next, the operation will be described with reference to a time chart of FIG. When the operation is started, first, the heater 13 is energized to heat the vaporizer 12. When the temperature of the vaporizer 12 detected by the vaporizer thermistor 14 reaches a predetermined temperature sufficient to vaporize the preset kerosene (preheating completed state), the electromagnetic pump 5 is first energized,
While the kerosene is supplied to the constant oil leveler 4 and the combustion blower 6 is energized, air is sent from the primary air supply port 8 into the carburetor 12, and the unburned gas in the carburetor 12 is discharged to clean the air. At the same time, the burner head 16 is heated (pre-purge step). At this time, the pressurizing solenoid 10 is in a position opposite to the direction shown in the drawing in a non-energized state, and the air supply path from the duct 7 to the pressurizing pipe 9 is closed.

When a predetermined time T ₁ has elapsed from the completion of preheating (point a in FIG. 5), the ignition heater 15 is energized and heated to a temperature sufficient to ignite the vaporized gas. Normally, when the vaporized gas is ignited by the ignition heater 15, for example, as shown in JP-A-1-239319, when the vaporized gas reaches the ignition heater 15, the ignition heater 15 reaches a predetermined temperature. As described above, energization is started before starting the ignition process.

[0005] Then, time T ₂ has elapsed since the completion of preheating,
When the ignition heater 15 is sufficiently red-hot, the pressure solenoid 10
(Point b in FIG. 5), the air supply path from the duct 7 to the pressurizing pipe 9 is opened, and the oil level of the constant oil level unit 4 is pressurized. When the oil surface is pressurized, the kerosene is supplied to the pipe orifice 11
Is supplied to the vaporizer 12. At this time, since the air is supplied from the primary air supply port 8, the kerosene is atomized and mixed with the air, and enters the vaporizer 12. The atomized kerosene is instantaneously vaporized in the high temperature vaporizer 12 to become a vaporized gas,
At the same time as passing through the burner head 16, it touches the red-heated ignition heater 15 to instantaneously ignite and start burning.

When the combustion starts, a flame current flows between the flame rod 17 and the burner head 16, and when this current reaches a predetermined ignition detection level, the power supply to the ignition heater 15 is stopped (point c in FIG. 5). ). The convection blower, which has been energized at the same time as the pressurized solenoid 10, blows out the high-temperature gas in the combustion tube 18 as hot air to the outside of the device body.

FIG. 6 is a structural view of a warm air heater having the above-described combustor incorporated therein. The combustion section including the burner head 16 is attached to a table 21 by a support frame 20. For example, when the warm air heater main body is placed on a moist soil or a grounded metal table, the support frame 20 and the table 21 are also made of metal.
Will be grounded.

FIG. 7 shows the flow of a flame current when the burner head 16 is grounded. In the figure, 2
2 is a DC power supply for applying a DC voltage between the frame rod 17 and the burner head 16, and 23 is a resistor for converting a flame current If flowing in the flame into a voltage when the voltage is applied, and one end thereof. Are input to a microcomputer (not shown). On the other hand, an ignition heater 15 is provided during the flame, and a relay 2 is applied to apply the commercial power 24 during the ignition.
Contact No. 5 is closed.

Generally, the ignition heater 15 is made of ceramic or the like. When the temperature of the ignition heater 15 rises to a high temperature, the insulation resistance decreases. Flame current I
f 'flows. Since the commercial power supply 24 has a high voltage of 100 V AC, it affects the flame detection circuit on the DC power supply 22 side,
Although the state of the flame is normal, a phenomenon occurs that the flame current If decreases.

Therefore, when the ignition operation is performed while the main body of the apparatus is grounded, for example, as shown by the dashed line in the time chart of FIG. May not rise to the ignition detection level, the flame detection means may determine that the ignition has not occurred, terminate the ignition operation at point d in FIG. 5, display an abnormal state, and stop.

[0011]

Since the conventional control device for a combustor is constructed as described above, when the main body of the apparatus is grounded, the flame detecting means is activated even though the ignition is normally performed. Since ignition cannot be detected, there is a major problem that combustion cannot be performed.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and it is possible to reliably detect ignition even when the apparatus body is used in a grounded state, and to shorten the energizing time of the ignition heater. The purpose of the present invention is to obtain a control device for a combustor that can extend the life of an ignition heater.

[0013]

A control device for a combustor according to the present invention comprises: a vaporizer for vaporizing liquid fuel; an ignition heater for igniting vaporized gas vaporized by the vaporizer;
A combustion unit for burning the vaporized gas, flame detection means for detecting a flame current in the combustion flame, and a microcomputer for control, wherein the microcomputer, when ignited, a flame current value detected by the flame detection means In the ignition determination, the determination is made with the ignition heater in a non-energized state, and the determination level is changed between when the ignition heater is energized and when the ignition heater is not energized.

[0014]

In the control device for a combustor according to the present invention, the ignition heater is de-energized, and the ignition detection is determined by changing the determination level between when the ignition heater is energized and when the ignition heater is de-energized. Therefore, the flame current can be measured without being affected by the ignition heater, and accurate ignition detection determination can be performed.

[0015]

[Embodiment 1] An embodiment of the present invention will be described below with reference to the drawings. FIG.
1 shows a block diagram of a control device for a combustor according to the present invention. The structure of the combustor is the same as the conventional example described with reference to FIG. In FIG.
Denotes an A / D conversion circuit 20a, an input circuit 20b, a CPU 20
c, memory (ROM, RAM, etc.) 20d, output circuit 20
e is a control microcomputer (hereinafter, referred to as a microcomputer) having a timekeeping function such as a timer, and has an input side for measuring an operation switch 21 for operating the combustor and a temperature of the vaporizer 12. And a frame rod 17 for detecting a flame formed on a burner head 16 which is a combustion part.

The vaporizer thermistor 14 and the frame rod 1
Since the signal from 7 is input as an analog voltage, it is converted into a digital signal by the A / D conversion circuit 20a in the microcomputer 20 and then taken into the CPU 20c to measure the temperature of the vaporizer 12 and the magnitude of the flame current. I do.

On the output side of the microcomputer 20, a heater 13 for heating the vaporizer 12 to a predetermined kerosene vaporization temperature, an electromagnetic pump 5 for supplying kerosene to the constant oil level unit 4, primary and secondary air for combustion are provided. Blower 6 for supplying oil, constant oil level 4
A pressure solenoid 10 for controlling oil level pressurization, an ignition heater 15 for igniting vaporized gas, and a convection blower 1 for blowing out high-temperature gas generated by combustion out of the apparatus main body.
9 are connected, and by controlling energization to these,
Control the combustor.

Next, the operation will be described with reference to the flowchart of FIG. 2 and the time chart of FIG. FIG.
In step 30, the operation switch is turned on in step 30 and the pressure solenoid 10 is turned on in step 39, and the convection blower 19 is turned on.
Until the switch is turned on, it is the same as the conventional example, and the description is omitted. When the pressure solenoid 10 is turned on in step 39 (b in FIG. 3)
Point), kerosene is supplied to the vaporizer 12 to become a vaporized gas,
It is ignited by the ignition heater 15. When ignited, a flame current flows, and in step 40, the timer sets the pressure solenoid 1
Step 41 is performed until it is determined that T ₃ seconds have elapsed since the on of 0.
The process proceeds, the flame current value to the ignition determination at a predetermined ignition detection level the If _1, when the flame current value becomes a predetermined ignition detection level the If ₁ or more, the process proceeds to step 42, by turning off the ignition heater 15, the combustion control to go into.

Meanwhile, when the device is used by being grounded, since the flame current hardly flows in the ignition determination of step 41, not the flame current value quite a predetermined ignition detection level the If _1, ignited by The ignition operation is continued despite the presence. Thus, if the timer has not reached the ignition detection level the If ₁ even after the elapse of T ₃ seconds after pressing solenoid 10 turned on at step 40, the process proceeds to step 43, the ignition heater 15 off (e point in FIG. 3) And then
The step 44 the ignition detection level the If ₁ in performing ignition judgment level of the determination is changed to a different ignition detection level the If _2. That is, in this embodiment, the ignition heater 1
5, the ignition detection level I of the flame current when power is supplied to
f is changing. That is, after the pressure solenoid 10 on, prior to the expiration T ₃ seconds and the ignition determination flame current the If ₁ (step 41), T ₃ after performs ignition determination flame current the If ₂ (step 44). At this time, If ₁ > If
If it is set to ₂ , the ignition heater 15 can be detected even if ignition is not detected while the equipment is grounded and the ignition heater 15 is energized.
When is turned off, ignition detection can be performed in a shorter time. Further, it is better that the time for detecting ignition by setting the ignition heater 15 to the non-energized state is as short as possible. This is because if the ignition heater 15 is not energized for a long time, the temperature of the ignition heater 15 becomes lower than the temperature at which it is possible to ignite the vaporized gas. Because. By doing so, the route of If 'in FIG. 7 is cut off, so that when the ignition is performed normally, the same flame current flows as when the equipment is not grounded, and the ignition detection level If _{2 is} easily obtained. (Point g in FIG. 3). That is, in FIG. 3, the portion indicated by the one-dot chain line is the operation when the device is grounded.

In addition, if there is any abnormality, the pressurized solenoid 1
If the ignition does not occur even if T ₄ seconds (T ₃ <T ₄ ) has elapsed since the operation of 0 (step 45), an abnormality is displayed and the ignition operation is stopped (step 46).

As described above, not only when the device is not grounded but also when it is grounded, the time until ignition detection can be shortened. Therefore, the optimal value of time T _3, for example, by setting the time to complete nearly ignition detection in normal use state of not being grounded, it does not require much longer time to ignition detection even when grounded Therefore, the energization time of the ignition heater 15 can be shortened, and the life of the ignition heater 15 can be extended.

[0022]

As described above, according to the present invention, when it is determined at the time of ignition that the flame detection means has ignited, the ignition heater is turned off and the determination is made.
Since the judgment level is changed between when the above-mentioned ignition heater is energized and when it is not energized, it does not require a long time until ignition is detected even when the equipment is grounded. Even when the ignition heater is used in a grounded state, it is possible to shorten the energization time of the ignition heater and obtain an effect of extending the life of the ignition heater.

[Brief description of the drawings]

FIG. 1 is a block diagram of a control device for a combustor according to an embodiment of the present invention.

FIG. 2 is a flowchart of a control device for a combustor according to one embodiment of the present invention.

FIG. 3 is a time chart of the control device of the combustor according to one embodiment of the present invention.

FIG. 4 is a structural view of a conventional combustor.

FIG. 5 is a time chart showing the operation of a conventional combustor.

FIG. 6 is a structural diagram of a warm air heater using a conventional combustor.

FIG. 7 is an explanatory diagram of flame detection of a conventional combustor.

[Explanation of symbols]

 12 carburetor 15 ignition heater 16 burner head 17 flame rod 20 microcomputer

────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-4-366315 (JP, A) JP-A-2-13713 (JP, A) (58) Fields investigated (Int.Cl. ⁶ , DB name) F23N 5/12 F23Q 7/22

Claims (2)

(57) [Claims] 1. A vaporizer for vaporizing a liquid fuel, an ignition heater for igniting vaporized gas vaporized by the vaporizer, a combustion unit for burning the vaporized gas, and a flame detector for detecting a flame current in a combustion flame. Means, and a microcomputer for control, wherein the microcomputer determines ignition at the time of ignition based on a flame current value detected by the flame detection means.
The ignition heater in the non-energized state.
The above-mentioned judgment is performed, and when the above-mentioned ignition heater is energized,
A control device for a combustor, wherein the ignition detection level is changed when power is supplied . 2. The method according to claim 1, wherein the change in the point ignition detection level is performed by a carburetor.
The control device for a combustor according to claim 1, wherein the control is performed a predetermined time after the start of fuel supply to the fuel cell .