JP3871788B2 - Overheat prevention device for combustion equipment - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an overheat prevention device that prevents damage to a body due to abnormal overheating of a combustion chamber or the like or fire due to wall overheating in a combustion device such as a gas water heater.
[0002]
[Prior art]
Conventionally, in order to prevent equipment burnout due to abnormal overheating of combustion equipment and fire due to wall overheating, an overheat prevention device has been known which is provided with a heat sensitive sheet that melts and breaks above a predetermined temperature between the combustion chamber and the casing. It has been.
The heat-sensitive sheet is obtained by printing a conductive pattern on the insulating sheet surface that melts at a predetermined temperature with conductive ink over the entire surface of the insulating sheet, and is provided on the rear surface of the combustion chamber 22 as shown in FIG.
When a hole is opened in the combustion chamber 22 and combustion exhaust gas is ejected, the heat-sensitive sheet 70 is partially melted and the conductive pattern is disconnected. Due to the disconnection of the conductive pattern, abnormal overheating due to combustion exhaust gas is detected, and combustion is stopped.
Such a heat sensitive sheet 70 is fixed to the rear surface of the casing 23 with screws 11.
[0003]
[Problems to be solved by the invention]
However, in the case where the thermal sheet 70 is arranged in front of the combustion chamber 22, there is a problem in that it becomes an obstacle when repairing the burner 27 and the like, and it is difficult to keep the distance between the combustion chamber 22 and the thermal sheet 70 at a constant interval. there were.
When the heat sensitive sheet 70 approaches the high temperature combustion chamber 22, the overheat prevention device 10 works even if it is normal, and when separated, the overheat prevention device 10 is activated even if the combustion chamber 22 is overheated. It will not work.
Therefore, the overheat prevention device for a combustion apparatus according to the present invention solves the above-mentioned problem, makes it possible to easily remove and attach the thermal sheet, and keeps the distance between the combustion chamber and the thermal sheet at a constant interval so as not to malfunction. The purpose is to detect abnormal conditions accurately.
[0004]
[Means for Solving the Problems]
The overheat prevention device for a combustion apparatus according to claim 1 of the present invention for solving the above-mentioned problems
A burner that burns fuel gas to heat the heat exchanger;
A combustion chamber in which the burner is burned;
A water pipe wound around the combustion chamber and through which hot water before or after heat exchange flows,
An outer casing that houses the combustion chamber;
A thermal sheet provided facing the combustion chamber and having a series of conductive patterns disposed on the insulating sheet over substantially the whole;
In an overheat prevention device for a combustion device, provided between the combustion chamber and the outer casing, and comprising combustion stop means for detecting disconnection of the conductive pattern or a change in electrical resistance and stopping combustion of the burner ,
A fixing plate for supporting the thermal sheet so that it does not bend on the back of the thermal sheet;
A clip attached to the fixing plate so as to sandwich the heat-sensitive sheet therebetween ,
The gist is to hold the clip in the water pipe and hold the heat-sensitive sheet in the water pipe at a predetermined distance from the combustion chamber.
[0006]
In the overheat prevention device for a combustion apparatus according to claim 1 of the present invention having the above-described configuration, the clip supporting the heat sensitive sheet is held between the water pipes and the distance from the combustion chamber to the heat sensitive sheet is kept at a predetermined distance.
Therefore, the overheat prevention device can accurately detect the abnormal state without malfunction.
Moreover, since the heat sensitive sheet can be removed or attached by detaching the clip held between the water pipes, the burner or the combustion chamber can be easily repaired.
[0007]
Also, deflection of sensitive heat sheet is corrected by a fixed plate provided on the back surface of the heat-sensitive sheet. What slave, the thermal sheet is corrected even when bending thin, since the distance between the combustion chamber and the heat-sensitive sheet as described above is secured to a fixed distance, desuperheater is accurately without malfunction Abnormal conditions can be detected.
[0008]
DETAILED DESCRIPTION OF THE INVENTION
In order to further clarify the configuration and operation of the present invention described above, a preferred embodiment of the overheat prevention device for combustion equipment of the present invention will be described below.
FIG. 1 is a schematic configuration diagram of a gas water heater provided with an overheat prevention device as one embodiment.
The gas water heater 20 is a wall-mounted forced air supply type water heater, and includes a casing 23 attached to a wall by a bracket 40, a combustion chamber 22 provided in the casing 23, and an upper side of the combustion chamber 22. The provided heat exchanger 25, the burner 27 that performs gas combustion in the combustion chamber 22, the supply fan 30 that supplies combustion air to the combustion chamber 22, and the combustion air discharged from the supply fan 30 A porous rectifying plate 33 that rectifies and sends it to the burner 27 is provided.
The gas conduit 26 serving as a gas supply path to the burner 27 is provided with an original electromagnetic valve 28 that opens and closes the gas flow path from the upstream side, and a proportional control valve 29 that adjusts the gas flow rate. The amount of combustion air and the gas flow rate are controlled by the controller 24.
Further, around the combustion chamber 22 and the heat exchanger 25, an overheat prevention device 10 that detects an abnormal overheat state and stops combustion is provided.
[0009]
As shown in FIG. 2, the heat-sensitive sheet 7 is a sheet-like insulating sheet that melts at a temperature equal to or higher than a predetermined value, and a series of conductive patterns 1 are printed with a conductive ink over the entire area.
In this heat-sensitive sheet 7, a PET film having a melting point of about 200 ° C. is used as an insulating sheet, and a mixture obtained by adding a resin to carbon is used as the conductive ink.
When the ambient temperature reaches a temperature equal to or higher than a predetermined value, the resin contained in the conductive ink expands, and the contact between the carbon particles is successively broken, the electrical resistance value increases, and finally the conduction is stopped. . At the same time, the conductive pattern 1 is broken when the insulating sheet melts and has holes.
The heat-sensitive sheet 7 has flexibility that can be freely bent so as to cover the periphery of the combustion chamber 22, and includes a front surface portion 10a, a right surface portion 10b, a rear surface portion 10c, which cover four surfaces of the combustion chamber 22. The left side surface portion 10d is integrally formed.
The heat sensitive sheet 7 is inserted and installed between the combustion chamber 22 and the heat exchanger 25 and the casing 23 (FIG. 1), covers the periphery of the combustion chamber 22 and the heat exchanger 25, and leads from the conductor pattern 1. Connected to controller 24 via line 34.
When the conductive pattern 1 of the heat sensitive sheet 7 is normal and conductive, the supply of fuel gas is continued. However, when local cracks or gaps are generated in the combustion chamber 22, high-temperature combustion exhaust gas is ejected and heat sensitive. While heating the sheet | seat 7 and increasing the electrical resistance value of the conductive pattern 1, on the other hand, an insulating sheet is fuse | melted and a hole is opened, and the conductive pattern 1 is disconnected.
When such an increase in electrical resistance value or disconnection occurs, the controller 24 closes the original electromagnetic valve 28 and stops the supply of fuel gas.
[0010]
In the front portion 10 a of the heat sensitive sheet 7 covering the front of the combustion chamber 22, a fixing plate 2 that is a rectangular thin plate and corrects the deflection of the heat sensitive sheet 7 is provided on the back surface of the heat sensitive sheet 7.
The fixing plate 2 is provided with two raised portions 2a formed by vertically cutting small pieces at the four corners and the central lower portion (FIG. 2), and mounting holes 2d for fixing a clip 3 described later at the central upper portion to the left and right respectively. Two are provided (FIGS. 2 to 4).
Further, the heat-sensitive sheet 7 is provided with two fixing holes 7a through which the cut and raised portions 2a are inserted at the four corners and the center lower portion, and similarly, two mounting holes 7d through which the clip 3 is inserted are provided at the left and right of the center upper portion. .
The clip 3 is made by bending an elastically deformable stainless steel plate, and the portion sandwiched between the water supply pipes 18 is formed in a U-shaped cross section, and each arm 3a elastically deforms facing up and down, and the back surface. The bottom surface 3b is in contact with the heat-sensitive sheet 7, and the mounting foot 3d is formed by bending the end of the bottom 3b in the opposite direction to the arm 3a on both sides of the lower arm 3a.
The clip 3 is formed so as not to waste as much as possible when removing the material. The lower arm 3a is provided between the left and right mounting feet 3d, and the upper arm 3a is provided on the left and right.
Also, the bottom surface 3b of the clip 3 is provided with a rib portion 3c with which the water supply pipe 18 abuts, and the arm portion 3a has a space between the tips of the opposing arm portions 3a in order to make it difficult to remove the water supply pipe 18 therebetween. Is narrower than the outer diameter of the water supply pipe 18.
Then, the end of the arm 3a has a curved surface on the inner holding surface so that the clip 3 can be easily held and slid only by being applied and pressed against the water supply pipe 18. So that it is curling.
[0011]
Next, the procedure for assembling the heat sensitive sheet 7 to the gas water heater 20 will be described.
First, the cut-and-raised portion 2a of the fixing plate 2 is bent in advance through the fixing hole 7a of the heat-sensitive sheet 7, and the front portion 10a of the heat-sensitive sheet 7 is fixed to the fixing plate 2 (FIG. 2).
Further, the mounting foot 3d of the clip 3 passes through the mounting hole 7d of the heat sensitive sheet 7 and the mounting hole 2d of the fixing plate 2, and is bent outside the fixing plate 2, so that the heat sensitive sheet 7 is placed inside the fixing plate 2. Fix in an overlapped state (FIGS. 2 and 3).
Then, the rear surface portion 10c of the heat sensitive sheet 7 is fixed to the casing 23 on the rear surface of the combustion chamber 22 together with the heat shield plate 19 that blocks the heat of combustion with screws 11 (FIGS. 1 and 2). The surface portion 10d is attached to the left and right side surfaces of the casing 23 with aluminum tape (not shown).
Further, in front of the combustion chamber 22, the water supply pipe 18 is fitted into the gap between each arm 3 a and the rib 3 c of the clip 3, so that the front part 10 a of the thermal sheet 7 is fixed to the water supply pipe 18 together with the fixing plate 2. Is done.
[0012]
From the above, the heat-sensitive sheet 7 of the overheat prevention device 10 of this embodiment is incorporated over the entire circumference of the combustion chamber 22 and is kept at a constant interval from the surfaces of the combustion chamber 22 and the heat exchanger 25.
Therefore, the overheat prevention device 10 can accurately detect the breakage of the combustion chamber 22 without malfunctioning such that the combustion chamber 22 is not damaged but is determined to be in an abnormal state. When repairing the combustion chamber 22 and the burner 27, if the front part 10 a of the heat sensitive sheet 7 is pulled together with the fixing plate 2, the clip 3 fitted in the water supply pipe 18 is detached, and the front of the heat sensitive sheet 7 is removed. The part 10a can be opened in the right direction.
Accordingly, when the combustion chamber 22 and the burner 27 are repaired, only the front surface of the seat can be removed and the rear surface of the seat can be fixed with the screw 11, so that the repair work is facilitated.
Furthermore, since the right side surface portion 10b and the left side surface portion 10d of the heat sensitive sheet 7 are affixed to the left and right side surfaces of the casing 23 with aluminum tape, no mounting bracket is required.
[0013]
As mentioned above, although the Example of this invention was described, this invention is not limited to such an Example at all, Of course, in the range which does not deviate from the meaning of this invention, it can implement in a various aspect.
[0014]
Further, the clip 3 and the fixing plate 2 are not limited to being provided on the front surface portion 10a, and may be provided on the rear surface portion 10c or the left and right side surface portions 10b and 10d.
[0015]
Further, the heat sensitive sheet 7 is not limited to being disposed around the entire combustion chamber 22, and may be disposed only on a predetermined surface of the combustion chamber 22.
[0016]
Further, the heat sensitive sheet 7 may be one in which the conductive pattern is disconnected or short-circuited due to melting when the temperature reaches a predetermined temperature, or the electric resistance value of the conductive pattern changes to exceed the reference range.
[0017]
【The invention's effect】
As described above in detail, according to the overheat prevention device for a combustion apparatus according to claim 1 of the present invention, the distance between the combustion chamber and the overheat prevention device is kept at a constant interval, so that malfunction does not occur and an abnormal state is maintained. an excellent effect called can be stopped accurately detect and combustion. Moreover, when repairing a combustion chamber and a burner, a thermal sheet can be easily attached or detached by detaching the clip held between the water pipes. Further, even when bending thin-sensitive heat sheet, is corrected by a fixed plate, it is possible to keep the distance between the combustion chamber and the desuperheater at regular intervals.
[Brief description of the drawings]
FIG. 1 is a schematic configuration diagram of an overheat prevention device for a combustion device as one embodiment.
FIG. 2 is a development view of an overheat prevention device as one embodiment.
FIG. 3 is a view showing a clip held in a water pipe.
FIG. 4 is a perspective view showing assembly of a clip.
FIG. 5 is a schematic configuration diagram of a combustion apparatus overheat prevention device as a conventional example.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Conductive pattern 2 Fixing plate 3 Clip 7 Thermal sheet 10 Overheating prevention apparatus 18 Water supply pipe 22 Combustion chamber 23 Casing 27 Burner

Claims (1)

A burner that burns fuel gas to heat the heat exchanger;
A combustion chamber in which the burner is burned;
A water pipe wound around the combustion chamber and through which hot water before or after heat exchange flows,
An outer casing that houses the combustion chamber;
A thermal sheet provided facing the combustion chamber and having a series of conductive patterns disposed on the insulating sheet over substantially the whole;
In an overheat prevention device for a combustion device, provided between the combustion chamber and the outer casing, and comprising combustion stop means for detecting disconnection of the conductive pattern or a change in electrical resistance and stopping combustion of the burner ,
A fixing plate for supporting the thermal sheet so that it does not bend on the back of the thermal sheet;
A clip attached to the fixing plate so as to sandwich the heat-sensitive sheet therebetween ,
The clip is sandwiched between the water pipe desuperheater combustion device, characterized in that the holding in the water pipe spaced a predetermined distance above the heat-sensitive sheet from the combustion chamber.

Images