JPS6298244A - Flame detecting sensor for burner - Google Patents

Abstract

PURPOSE:To detect a flame accurately under the combustion conditions in wide range by arranging a pair of the electrodes having the length corresponding to the displacement of the flame of a burner by bringing it into contact with the outer periphery of the flame as well as by pinching the flame and in the same direction as the flames. CONSTITUTION:A flame rod 6 is composed of the plate like earth electrode 62 which is formed by extending to the upper face of a combustion plate 4 along the inner side face 43A of a fireproof frame 43, and the needle like power source side electrode 64 which is equipped with the horizontal lever part 64A which is fixed to the wall face by a fixing means 63 by being arranged by penetrating into the combustion box wall face of the upper part of the earth electrode 62 and the vertical lever part 64B which is extended to the lower part from the end thereof and the lower of which is abutted to the upper face of the combustion plate 4. These electrodes 62, 64 pinch one small hole 4a of the inside of small crater group which is provided on the combustion plate 4 and provide the length in the vertical direction corresponding to the displacement of the flame 4F to be caused on the small hole 4a. Consequently the flame is accurately detected with the one part of both electrodes 62, 64 being always abutted to the combustion reaction zone even if the flame be displaced in a wide range from the case of the lift of the flame 4F being caused by the high load combustion immediately after the ignition until the flame 4F is located at the vicinity of the small hole 4a by the low load combustion.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a flame rod device used as a flame detection sensor in a combustion separator safety device.

[Conventional technology] Combustion equipment such as gas lagoon boilers and space heaters has a technology that detects loss of flame due to misfires due to blowing out or misfires, etc.
A safety device is installed that stops the gas supply in the event of such an abnormality. As a sensor for this flame, a flame rod device is used in which a pair of electrodes are provided to sandwich the flame. Conventionally, this flame rond method involves placing one electrode at the top of the flame so as to intersect with the flame, and placing the other electrode at the base of the flame, or using the rim of the burner as the other electrode.
Furthermore, one of the methods of arranging twin electrodes in contact with an insulating t1 combustion plate (Utility Model Publication No. 58-23084) was adopted.

[Problems to be solved by the invention] In recent years, combustion equipment has been required to be more compact and to increase calorific value (high-load combustion). (burner) is preferably used. In this forced air burner, the position of the flame (combustion reaction zone) inevitably shifts significantly from near the burner nozzle to a far position as the combustion conditions and heat load change, and the reaction zone is narrow. However, with all of the above methods, accurate flame detection is possible only when the reaction zone is wide and has little variation, and it is difficult to accurately detect flame when the reaction zone is narrow and largely displaced. .

An object of the present invention is to provide a burner flame detection sensor that can accurately detect the presence or absence of a flame even when the displacement of the flame (reaction zone) position is large.

Means for Solving the Problems] To achieve the above object, the burner flame detection sensor of the present invention includes a pair of electrodes having a length corresponding to the displacement of the flame of the barb in the same direction as the flame. A configuration was adopted in which the flame was sandwiched and the flame was placed in contact with the outer periphery of the flame.

[Operation and Effects of the Invention 1] This bar flame detection sensor J has an electrode of the flame rod coaxial with the flame of the barb and has a length corresponding to the displacement of the flame by λ1, so that the flame detection sensor J has a length corresponding to the displacement of the flame. A part of the electrode constituting the flame rod can reliably contact the reaction zone from when the air 8 is low and the reaction zone is near the crater to when the flame lifts and the reaction zone is displaced upward. This allows for accurate flame detection under wide range combustion conditions from low-load combustion to high-load combustion.
It is highly effective in detecting flames in all-primary air combustion type burners that achieve complete combustion and have a narrow reaction zone.

[Example 1] Figures 1 and 2 show an instantaneous gas water heater with a safety device (=J) using the burner flame detection sensor of the present invention.

This water boiler includes a combustion box 10 whose inside is a combustion chamber, a forced-air gas combustion device (burner) 1 of all-primary air combustion type that completely burns only with secondary air, and the combustion box 10. a heat exchanger 2 equipped with a plate fin group 21 arranged on the upper part of the combustion box and having both ends welded to the inner wall of the combustion box, and a heat exchanger 2 that houses the combustion box 10 and the burner 1, and an outside air inlet 3 at the lower part of the side wall.
1 and a control device 5 for the burner 1.

The combustion box 10 has a rectangular cross section, has a υ1 electricity 10A connected to the exhaust pipe 11 at the upper end, has an opening at the lower end, and has a mixing box 14 inside which is a mixing chamber 1A for fuel gas and air. is provided to cover the lower end opening. On the flange 12 circumferentially provided at the upper end of the mixing box 14 described in 07i, a group of small holes consisting of small holes placed on the front and back are provided, for example, in a matrix shape, and a fireproof insulating material such as an electrically insulating ceramic sintered body is provided. A combustion plate 4 made of stainless steel is placed thereon, and a blower 13 for supplying air to the mixing box 14;
A gas supply pipe 17 having a jet q4015 is attached near the outlet of the blower 13 to form the barb 1.

The small holes 4a, 4 of the combustion plate 4 have various types of small holes 4a, 4 whose ventilation resistance is varied by means such as providing a difference in cross-sectional area.
b, 4c, . . . , and the number of flames generated at each small vent is appropriately dispersed to prevent the generation of noise due to resonance with the combustion box 10 or the exhaust pipe 11.

As shown in FIG. 3, the combustion plate 4 is attached in this embodiment by being formed separately from the combustion plate 4, with its "shaped cross section right, and holding the upper peripheral edge 4AJ3 and outer circumferential side surface 4B of the combustion plate 4. A ceramic refractory frame 43 is fitted over the combustion plate 4, and is further molded from a stainless steel sheet metal.
A side plate portion 458 is tightly fitted to the outer circumferential side wall of the frame, a locking plate portion 45B extends inward from the upper end of the side root portion 45A and locks the upper surface of the fireproof frame 43, and a locking plate portion 45B extends from the lower end of the side root portion 45A. The upper and side surfaces of the refractory frame 43 are held in place by a frame-shaped fixture 45 consisting of an outwardly extended flange 45C, and the side plate portion 45A is attached to the small end (2) of the combustion box 10 marked +'+Q. At the same time, the flange 45C is attached to the combustion box 1.
0 and the mixing box 14
It is sandwiched between the flange 12 and fastened with bolts 19. Note that the fireproof frame 43 is a combustion plate 4.
Although they may be formed integrally with each other, it is preferable to form them separately as in this embodiment in order to improve thermal shock resistance.

The control device 5 includes a flame rod 6 which serves as a pair of electrodes provided on the upper surface of the combustion plate 4 in order to detect the presence or absence of a flame in the combustion device 1, and a jacket (electromagnetic) provided in the gas supply pipe 17. ) valve 51 and flow control valve 53, the combustion plate 4
The safety valve 51, the flow control valve 53, and the ignition device 55, 57 are activated according to the operation of the two two-pole sparkers 55, 57, which are igniters provided on the top surface, and the operation means (not shown).
It also includes a control circuit 50 that controls the motor M of the blower 13 and generates an output that automatically closes the safety valve 51 when a misfire or ignition error of the frame rod 6 is detected.

The frame rod 6 is connected to the locking plate portion 45 of the fixing fitting 45.
It is formed by extending a part of 8 and bending it downward,
A plate-shaped ground electrode 62 is formed extending along the inner surface 43A of the refractory frame 43 to the upper surface of the combustion plate 4, and a plate-shaped ground electrode 62 is disposed along the wall surface of the combustion box above the ground electrode 62,
Horizontal rod part 64A fixed to the wall surface by fixing means 63
a3 and a needle-shaped power source side electrode 64 having a vertical rod portion 64B extending downward from the stout and having a lower end in contact with the soil surface of the combustion plate 4 at 11 times. Note that the ground electrode 62 may be formed separately from the fixture 45 and fixed to the fixture 45 or the combustion box 10 with a fastener such as a screw.

These electrodes 62 and 64 sandwich one small hole 4a of the small crater group provided on the combustion plate 4, and have a vertical shape corresponding to the displacement W of the flame (combustion reaction zone) 4F generated in the small hole 4a. Be prepared. As a result, from the case where flame 4 [lifts] due to high-load combustion immediately after ignition, as shown in Figure 4, to the case where flame 4F lifts due to low-load combustion, as shown in Figure 5, it spreads over a wide range. Even if the flame is displaced, a portion of both electrodes 62 and 64 is always in contact with the combustion skin zone, so that the flame can be detected accurately.

FIG. 6 shows another embodiment of the frame rod 6.

In this embodiment, a strip electrode 64 is used instead of the needle electrode 64.
C is used, and serves as a guard and guide plate for the flame 4F during low-load combustion, and also prevents deformation due to a decrease in rigidity during high-load combustion.

Incidentally, the electrode of the frame rod 6 may have a needle or rod shape for both the power source and the ground, and the lower end thereof does not necessarily have to be in contact with the upper surface of the combustion plate 4.

[Brief explanation of drawings]

Figure 1 is a schematic cross-sectional view of a forced air instantaneous gas lagoon boiler, Figure 2
The figure is a perspective view of the main parts, FIG. 3 is a perspective view of the combustion plate fixing means, FIGS. 4 and 5 are enlarged views of the frame rod, and FIG. 6 is an enlarged view of the frame rod of another embodiment. be. In the diagram 1... Forced air gas combustion device (burner) 2.
...Heat exchanger 3...Water boiler case 4...Combustion plates 4a, 4b, 4c...Small crater 4F...Flame 5
...Control device 6...Frame rod 62.64.
...Frame rod electrodes Fig. 1 Fig. 2 Fig. 3 Fig. 4 Fig. 5

Claims (1)

[Claims] 1) A burner comprising a pair of electrodes having a length corresponding to the displacement of the flame of the burner, arranged in the same direction as the flame, sandwiching the flame, and in contact with the outer periphery of the flame. Flame detection sensor. 2) The burner has an electrically insulating combustion plate provided with a large number of small holes penetrating the front and back sides, and one or both of the electrodes are arranged with one end in contact with the combustion plate. A flame detection sensor for a burner according to claim 1. 3) The flame detection sensor for a burner according to claim 1, wherein the electrode has a band-like shape and also serves as a guard for the flame.