JP2000055359A - Ignition detector for combustion device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an ignition detector for a combustion device capable of detecting an ignition in a stable ignition time without being influenced by room temperature in an environment ranging from low temperature to high temperature. SOLUTION: This ignition detector for a combustion device comprises a flame current detecting means 9 for detecting a flame current of a combustion flame, a room temperature detecting means 7 for detecting a room temperature, an ignition judging means 13 for judging success or failure of an ignition on the basis of a signal from the flame current detecting means 9 and an ignition judgment level selector means 14 for selecting a flame current value level used by the ignition judging means 13 for judging the ignition. In this case, the ignition judgment level selector means 14 can be used for stepwisely selecting a flame current value level used by the ignition judging means 13 for judging the ignition according to the room temperature signal from the room temperature detecting means 7.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for detecting the ignition of a combustion appliance, such as a hot air heater, which vaporizes and burns a liquid fuel.

[0002]

2. Description of the Related Art A hot air heater as shown in FIG. 4 is an example of a burner for vaporizing and burning a liquid fuel. In FIG. 4, reference numeral 1 denotes a main body case, and 2 denotes a combustion unit for vaporizing and burning a liquid fuel, and includes a carburetor 2a, an electric heater 2b, a burner head 2c, and the like. Three
Is a combustion blower that supplies combustion air to the combustion section 2,
4 is a fuel tank, 5 is an electromagnetic pump that supplies the liquid fuel in the fuel tank 4 to the combustion unit 2, 6 is convection that draws indoor air, mixes it with hot air generated by the combustion of the combustion unit 2, and blows air indoors. A fan 7, a room temperature detector 7 for detecting the room temperature, an ignition device 8 for igniting the combustion section 2, and a frame rod 9 for detecting the flame current of the combustion flame 10.

FIG. 5 is a block diagram showing a conventional ignition detection device for a warm air heater. Reference numeral 11 denotes an operation switch, and 12 controls the electromagnetic pump 5, the combustion fan 3, the ignition device 8, and the like.
A combustion control unit 13 for performing combustion is ignition determination means.

In the conventional ignition detection device having the above-described configuration, when the power switch 11 is turned on to start the operation, the electric heater 2b is energized to heat the side wall of the vaporizer 2a. Then, when the vaporizer is heated until a temperature required for vaporizing the liquid fuel, for example, 200 to 300 ° C., is detected, the combustion air blower 3 is driven to send the combustion air, which is supplied into the vaporizer 2 a. Is done. At the same time, the fuel pump 5 is driven to supply the liquid fuel in such an amount that the primary air ratio (= supply air amount / theoretical air amount) becomes about 0.7 to 0.8 into the carburetor 2a.

The liquid fuel supplied into the vaporizer 2a is atomized by the flow of the combustion air and is instantaneously vaporized by the heat of the vaporizer 2a, mixed with the combustion air and ignited by the burner head 2c. It is ignited by the device 8 to form a combustion flame 10 and burn. The flame rod 9 detects the flame current value IF of the combustion flame 10, and when the detected flame current value exceeds the ignition determination level, it is determined that the ignition is completed, the ignition operation is completed, and the normal combustion control is started. Transition.

[0006]

In the conventional ignition detection device as described above, the fuel supplied by the fuel pump 5 is not affected by the change in room temperature, but the amount of combustion air is the same as the combustion level. Also, as the room temperature becomes lower, the air density increases. For this reason, the supplied combustion air amount increases in proportion to the air density, and as a result, the primary air ratio increases. As a result, as the room temperature decreases, the state of the combustion flame 10 formed is lift combustion in which the air is in an excess air state, and the flame current value If of the combustion flame 10 detected by the frame rod 9 is, as shown in FIG. a2>a3> a4, it is difficult to reach the determination level of the flame current value required for ignition detection, and the time required for ignition is also T
1 <T2 <T3, resulting in a problem that ignition characteristics are deteriorated. The present invention solves the above-described problems.By changing the ignition determination level of the flame current value according to the room temperature at the time of ignition, it is possible to always perform stable ignition detection regardless of the difference in temperature. The purpose is to do so.

[0007]

According to the present invention, there is provided an ignition control apparatus for a liquid fuel combustion apparatus, comprising: a flame current detecting means for detecting a flame current of a combustion flame; a room temperature detecting means for detecting a room temperature; An ignition determination unit that determines the presence or absence of ignition according to a signal from the detection unit; and an ignition determination level switching unit that switches a level of a flame current value at which the ignition determination unit determines ignition. The level of the flame current value for which the ignition is determined by the ignition determining means is switched stepwise in accordance with a signal from the room temperature detecting means.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiment 1 Hereinafter, Embodiment 1 of the present invention will be described with reference to the control block diagram of FIG. 1 and the configuration diagram of FIG. The configuration of the combustion apparatus according to the first embodiment is substantially the same as the conventional configuration shown in FIG. 3, and thus the description thereof is omitted. Figure 1
In FIG. 2, reference numeral 2 denotes a combustion unit including a carburetor 2a, an electric heater 2b, a burner head 2c, etc., 5 denotes a fuel supply unit such as an electromagnetic pump for supplying fuel to the combustion unit 2,
Reference numeral 3 denotes combustion air supply means such as a combustion blower for supplying combustion air to the combustion section 2, reference numeral 7 denotes room temperature detection means for detecting room temperature, reference numeral 8 denotes an igniter, and reference numeral 9 denotes a flame current flowing through a combustion flame 10. It is a flame current detecting means such as a frame rod.

Reference numeral 11 denotes an operation switch, reference numeral 12 denotes a combustion control unit for controlling the fuel supply means 5, combustion air supply means 3, ignition means 8 and the like to perform combustion, and reference numeral 13 denotes a signal from the flame current detection means 9. Ignition determination means for determining ignition by
Reference numeral denotes ignition determination level switching means for switching a flame current value which becomes an ignition determination level in multiple stages in accordance with a signal from the room temperature detecting means 7.

Next, the ignition detection operation in the above configuration will be described with reference to the control flowchart of FIG. First, when the operation switch 11 is turned on (step 2).
0), the combustion control unit 12 energizes the electric heater 1b of the combustion unit 2 to start preheating the carburetor 2a (step 21).
When the preheating of the vaporizer 2a is completed (step 22), the current room temperature is detected by the room temperature detector 7 (step 23).

Next, the ignition determination level switching means 14 selects an ignition determination level corresponding to the detected room temperature from among the ignition determination levels set in four stages corresponding to the room temperature, based on the signal from the room temperature detector 7. Then, the ignition determination level of the ignition determination means 12 is set (step 24). That is, in the first embodiment, as shown in FIG. 3, when the room temperature t at the time of ignition is 10 ° C. ≦ t, the ignition determination level switching means 14 sets the ignition determination level of the flame current value If to 1 and the ignition When the room temperature t is 0 ° C ≦ t <10 ° C., the ignition determination level is set to level 2, and when the room temperature t at the time of ignition is −10 ° C. ≦ t <0 ° C., the ignition determination level is set to level 3, and further ignition When the room temperature t at this time is t <−10 ° C., the determination level of the ignition determination means 13 is switched so that the ignition determination level is set to level 4.

When the setting of the ignition determination level of the flame current value is completed, the combustion control unit 12 rotates the combustion blower 3 so as to attain a preset air-fuel ratio at the time of ignition (step 25), and performs pre-purge. Start. When the prepurge is completed (step 26), the ignition device 8 and the electromagnetic pump 5 are turned on (step 27). At this time, the relationship between the liquid fuel supplied to the vaporizer 2a by turning on the electromagnetic pump 5 and the combustion air from the combustion blower 3 is such that the primary air ratio (= supply air amount / theoretical air amount) is 0.7. ~ 0.8
To be kept to a degree. When the fuel is supplied to the vaporizer 2a and the vaporized gas is generated, when the vaporized gas reaches the burner head 2c, it is ignited by the spark of the ignition device 8.

When the combustion flame 10 is formed, a flame current flows from the flame rod 9 to the burner head 2c. The flame current value IF changes depending on the air-fuel ratio, and becomes smaller as the room temperature at the time of ignition is lower. However, as described above, the ignition determination level is set in four steps according to the room temperature, so that the flame current value can be obtained even in a low temperature environment. The time T1 until the IF reaches the ignition determination level does not need to be so long, and is almost the same as in the high-temperature environment and is constant.

When the flame current value If reaches the ignition determination level and the ignition determination means 13 determines that ignition has been completed (step 2).
8) The combustion control unit 12 turns off the ignition device 8 (step 29), and the combustion control unit 12 sets the air-fuel ratio during ignition to the air-fuel ratio during normal combustion and shifts to normal combustion control.

[0015] The flame rod 9 detects the flame current value If of the combustion flame 10 thus formed, and when the detected flame current value IF exceeds the ignition determination level, the ignition determination means 13 determines that the ignition is completed. As a result, the combustion control unit 12 completes the ignition operation, so that the time T1 required for the ignition detection becomes substantially constant regardless of the room temperature from the low temperature environment to the high temperature environment as shown in FIG. It becomes possible. In the first embodiment, when the preheating is completed, the ignition determination level of the flame current value IF is switched according to the indoor temperature signal obtained from the room temperature detector 7 that detects the indoor temperature. When the ignition device 8 starts discharging, the ignition determination level of the flame current value IF may be switched.

[0016]

As described above, according to the present invention, the ignition determination level of the flame current value is switched in consideration of the change in the air density of the combustion air that changes according to the room temperature at the time of ignition. The effect is obtained that stable ignition detection can be performed from a low-temperature environment to a high-temperature environment, and the time required for ignition detection can be made substantially constant regardless of the room temperature.

[Brief description of the drawings]

FIG. 1 is a block diagram of an apparatus for detecting ignition of a combustion appliance according to a first embodiment of the present invention.

FIG. 2 is a control slow chart according to Embodiment 1 of the present invention.

FIG. 3 is a graph showing a relationship among a room temperature, a flame current value, and an ignition determination level according to the first embodiment of the present invention.

FIG. 4 is a simplified cross-sectional view showing a configuration of a conventional burning appliance.

FIG. 5 is a block diagram showing a conventional ignition detection device for a combustion appliance.

FIG. 6 is a graph showing the relationship among room temperature, flame current value, and ignition determination level in a conventional ignition detection device.

[Explanation of symbols]

2 Combustion unit, 3 Combustion air supply means (combustion blower), 5 Fuel supply means (electromagnetic pump), 7 Room temperature detector, 8 Ignition device, 9 Flame current detection means (flame rod), 10 Combustion flame, 12 Combustion Control unit, 13 ignition determination means, 14 ignition determination level switching means.

 ────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Katsuya Fukuno 2-3-2 Marunouchi, Chiyoda-ku, Tokyo F-term in Mitsubishi Electric Corporation (reference) 3K005 WA01 WC01 YA01 YA21

Claims (1)

[Claims] 1. A flame current detecting means for detecting a flame current of a combustion flame, a room temperature detecting means for detecting a room temperature, and an ignition judging means for judging the presence or absence of ignition according to a signal from the flame current detecting means. And an ignition determination level switching means for switching the level of a flame current value at which the ignition determination means determines ignition. The ignition determination level switching means responds to a signal from the room temperature detection means by a flame current of the ignition determination means. An ignition detection device for a combustion appliance, wherein an ignition determination level of a value is switched stepwise.