JPH0462007B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a flame sensor that detects a flame or its state within a combustion chamber.

[Prior Art] Conventionally, in order to detect the combustion state of fuel in the combustion chamber, the temperature at that time, the temporal distribution state, etc., a light detection member that penetrates the wall of the combustion chamber is used to detect the flame generated by combustion. A sensor is used (for example, Japanese Patent Application Laid-Open No. 55-47428). This guides the combustion light inside the combustion chamber to the outside, and there are known ones that use quartz glass and optical fiber as the light detection member (for example, US Pat. No. 4,422,321).

FIG. 2 is a sectional view showing the configuration of an example of a conventionally used flame sensor. In the figure, 1 is a flame sensor, and 2 is an opto-coupler that photoelectrically converts combustion light guided out of the combustion chamber via the flame sensor 1. In actual use, the two are fitted together. The flame sensor 1 consists of a quartz glass rod 3, a metal case 5, an adhesive 7, and an O-ring 10, and the quartz glass rod 3 is bonded to the metal case 5 with the adhesive 7 over almost its entire length. metal case 5
A part of the outer periphery (5a) is male threaded,
This fixes the flame sensor 1 to the outer wall of the combustion chamber. On the other hand, the optocoupler 2 includes a photoelectric conversion element (for example, a phototransistor) 11 and a resin holder 1.
2. Consisting of a metal case 14, a resin filler 16, a wire (electric wire) 18, and a wire holder 19, the photoelectric conversion element 11 is placed inside the metal case 14 and the resin holder 1
2, it has a fixed structure. O-ring 1
0 acts as a buffer material when fitting the flame sensor 1 to the optocoupler 2.

[Problems to be Solved by the Invention] In this prior art, an optical member such as quartz glass 3 used as a light detection member and a fixing member (metallic in FIG. The coefficient of thermal expansion is different from case 5). Therefore, if the photodetecting member is fixed over almost its entire length to a fixed member using adhesive, etc., the fixed member will become hot during combustion due to the difference in coefficient of thermal expansion between the two, and this will cause tension to be applied to the photodetecting member such as a quartz glass rod. There was a problem that the glass rod could break due to stress. Also, when installing the flame sensor on the combustion chamber wall, if a slight twist is applied, the glass rod may break due to the torsional stress, or if a load is applied in a lateral direction to the longitudinal direction of the fixing member when handling the flame sensor alone. It was also thought that the glass rod could break due to bending stress.

To solve this problem, some proposals have been made to support the photodetecting member, such as quartz glass, with cushioning material, etc. without fixing it with any adhesive, etc. However, simply supporting the photodetecting member is insufficient to ensure the accuracy of the position of the photodetecting member. There was a problem in that it could not be removed, and it could become displaced due to external shocks, thermal expansion, etc., and this has not been a sufficient solution.

[Object of the Invention] The present invention has been made in view of the above points, and its object is to create a flame that does not cause damage to the photodetecting member due to thermal expansion due to temperature rise in the combustion chamber or normal handling. The purpose is to provide sensors.

[Configuration of the Invention] The configuration of the present invention made to achieve the above object includes: a rod-shaped light detection member that penetrates a wall of a combustion chamber and guides combustion light inside the combustion chamber to the outside of the combustion chamber; a fixing member fixed inside and attached to the combustion chamber wall, the fixing member fixing the light detection member on a side opposite to the combustion chamber side, and the fixed part The gist of the present invention is a flame sensor characterized in that the light detection member is supported only through a vibration prevention material that is in contact with the outer periphery of the light detection member on the side closer to the combustion chamber.

[Operation of the invention] The flame sensor having the above configuration does not fix the light detection member such as a quartz glass rod to a fixed member such as a metal case over its entire length, but instead fixes the light detection member such as a quartz glass rod to the side opposite to the combustion chamber side (low temperature side during combustion). The photodetecting member is fixed to the fixed member only on the side where the photodetecting member is fixed, and on the other hand, on the side where the photodetecting member is fixed, on the side closer to the combustion chamber, a vibration preventing material, such as an O-ring-shaped rubber elastic body, etc., is attached to the outer periphery of the photodetecting member. The fixing member is configured to be supported within the fixed member via the fixing member.

Therefore, even if the temperature of the outer wall of the combustion chamber rises during combustion and the fixing member is also heated, the light detection member is not fixed along its entire length, but only near the end farthest from the combustion chamber. Therefore, breakage of the photodetecting member due to differences in thermal expansion hardly occurs. In addition, the problem of natural vibration at the open end that occurs in a cantilever structure in which the photodetecting member is fixed at only one end can be solved by using vibration prevention material only on the side of the photodetecting member that is not fixed to the fixing member. This problem has been solved by a configuration in which the problem is supported by a fixed member via the . That is, vibration is applied to the flame sensor through the combustion chamber, etc., and the various vibration frequency components contained in this vibration cause the photodetecting member fixed in the form of a cantilever to resonate at its natural frequency. The possibility that the sheath-like fixing member housing the photodetecting member will be damaged by contact with the sheath-like fixing member is avoided in advance by the anti-vibration material that contacts the outer periphery of the photodetecting member and supports it within the fixing member.

The light detection member may be any material that can transmit and transmit flame well, that is, light from the entire visible light range to the infrared range, and materials with relatively melting points such as quartz glass, borosilicate glass, and potash glass may be used. High-quality glass materials, corundum which is alumina crystal, translucent ceramic based on alumina, zirconia, thoria, etc., crystals such as quartz, etc. can be molded and used according to the usage as a flame sensor. good.

Further, metal is usually used as the fixing member, but the material, shape, etc. may be determined by considering processing, cost, method of attachment to the outer wall of the combustion chamber, etc.

Furthermore, while O-ring-shaped rubber elastic bodies are commonly used as vibration-preventing materials, silicone rubber, other highly elastic resins, or polymeric materials may be used, taking into account the rigidity and natural frequency of the photodetecting member. , one or more may be provided at appropriate positions. The vibration preventing material is in contact with the outer periphery of the photodetecting member, and if a rubber elastic body or the like having a sealing property is used, it can also have the function of sealing the combustion chamber side and the outside.

[Example] Hereinafter, an example of the present invention will be described in detail based on the drawings.

FIG. 1 is a sectional view along the axis of a flame sensor according to an embodiment of the present invention. In the figure, 30 is a quartz glass rod as a light detection member, 32 is a heat-resistant metal such as SUS310S that can withstand a combustion atmosphere of 1000°C, and in the event that the quartz glass rod 30 is broken, fragments will fall into the combustion chamber. 33 is a mounting case forming a part of the fixing member; 35 is a metal case forming another part of the fixing member and fixing the quartz glass rod 30 with adhesive 37; 39; 1 and 2 respectively represent a fluoro rubber O-ring that serves as a vibration-preventing material and a pressure sealing material. The mounting case 33 has a male screw 33a cut on the outside, and is attached to a combustion chamber wall (not shown) by the male screw 33a. Further, the O-ring 39 supports the quartz glass rod 30 inside the mounting case 33,
The quartz glass rod 30 does not touch the mounting case 33 except at the O-ring 39. For this reason, there is a gap (approximately 0.1 mm) between the quartz glass rod 30 and the mounting case 33.
A gap 40a or a gap 40b (approximately 0.3 mm) is formed. The mounting case 33 and the metal case 35 are caulked at the K portion, and the protective case 32 and the mounting case 33 are brazed in advance at the R portion. Therefore, by placing the quartz glass rod 30 and O-ring 39 inside and caulking, the above-mentioned cases are integrated.

Note that 41 is a fluorine resin ring that backs up the O-ring 39, and 43 is a fluorine resin ring 41 that is held between the mounting case 33 and the metal case 35.
A metal ring 45 is used to secure the quartz glass rod 30 to the metal case. The fluorine resin ring 41 is made of a fluorine rubber O-ring 39 (hardness 90°) with a compression ratio of 20
When used at ~30%, the pressure applied from the combustion chamber side is backed up, and the gap between the O-ring 39, the mounting case 33, and the quartz glass rod 30 is made as small as possible, for example, 0.
~0.1 mm to prevent the O-ring 39 from deforming into the gap due to pressure. In the example, O
Ring 39 has a pressure resistance of 150Pa. The metal ring 43 backs up the fluororesin ring 41 and forms a gap 47 at the end of the metal case 35. This gap 47 prevents the problem that when fixing the quartz glass rod 30 to the metal case 35, excess adhesive 37 may protrude and adhere to the O-ring 4, reducing its pressure resistance.

Next, the assembly of this flame sensor will be explained. A gasket 45 is previously fitted onto one end of the quartz glass rod 30, and adhesive 37 is applied to the outer periphery of the rod, avoiding the gasket 45 and extending about 1/3 toward the center of the rod. After placing this in the metal case 35, from the other end of the quartz glass rod 30, a metal ring 43, a fluororesin ring 41,
Fit the O-ring 39 in this order, and then install the protective case 32.
Fit the mounting case 33, which has been brazed to the metal case 35, and caulk at the K part. This is erected vertically with the quartz glass rod 30 facing the protective case 32 side upward, and heated from the outside. The adhesive 37 is thermally cured by heating, but just before curing, the adhesive 37 is heated and its viscosity temporarily decreases. However, since the packing 45 is fitted around the lower end of the quartz glass rod 30, the adhesive 37 does not flow out and adhere to the end surface of the quartz glass rod 30, thereby preventing the translucency from being obstructed. After the adhesive 37 is hardened by heat curing, this flame sensor is fitted onto the optocoupler.
The optocoupler incorporates a photoelectric conversion element (here, a phototransistor) 54 soldered to a substrate 53 via a resin holder 52 in a coupler case 50. It converts light into electrical signals. Wires 56 for transmitting electrical signals to the outside are soldered to the substrate 53, and the entire substrate 53 is further molded with a resin filler 58.
The metal case 3 of the flame sensor is inside the coupler case 50.
After fitting 5, turn and swage the M part to fix it. Note that 59 is an O-ring that functions as a damper and waterproof when the metal case 35 and coupler case 50 are fitted together.

In this embodiment configured as above,
The quartz glass rod 30 is fixed with an adhesive 37 only to the metal case 35 on the opposite side of the combustion chamber, and is supported only by the O-ring 39 without directly touching the mounting case 33 from this fixed point on the combustion chamber side. has been done. Therefore, even if the temperature of the combustion chamber becomes high, the temperature of the metal case 35 will rise more slowly than this, and the tensile stress applied to the quartz glass rod 30 due to thermal expansion is also low, and moreover, the part where the stress acts is the quartz glass rod. Since the quartz glass rod does not extend over its entire length, the quartz glass rod will not be damaged by this.
Also, the combustion chamber side of the quartz glass rod 30 is attached to the mounting case 3.
Since the flame sensor 3 is housed with gaps 40a and 40b inside the quartz glass, even if the flame sensor is distorted when attached to the combustion chamber wall or if the mounting case 33 is twisted or bent when handled as a single unit, the quartz glass Since no force is directly applied to the rod 30, such handling will not cause damage or the like.

On the other hand, the problem of vibration in such a cantilever-shaped installation has been sufficiently solved by the O-ring 39, but this O-ring also serves as a seal between the combustion chamber and the outside world, and the two This role also contributes to lower costs by simplifying the structure and reducing the number of parts.

In this embodiment, the flame sensor section that extracts combustion light and the optocoupler section that performs photoelectric conversion are integrated by caulking, but there is no problem in using a separate type as shown in Fig. 2 explained in the section of the prior art. .

Although the embodiments of the present invention have been described above, the present invention is not limited to these embodiments in any way.
It goes without saying that the invention can be implemented in various ways without departing from the gist of the invention.

[Effects of the Invention] As detailed above, according to the flame sensor of the present invention, the light detection member is not damaged by stress such as thermal expansion due to temperature rise accompanying combustion or unexpected twisting or deflection during handling. It has an excellent effect that never happens. Furthermore, sufficient structural resistance can be exhibited against vibrations and pressure transmitted through the combustion chamber.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view showing a cross section along the axis of a flame sensor as an embodiment of the present invention, and FIG. 2 is a similar cross-sectional view showing a conventional technique. 30...quartz glass rod, 33...mounting case, 35
...Metal case, 37...Adhesive, 39...O ring.

Claims (1)

[Scope of Claims] 1. A rod-shaped light detection member that penetrates the wall of the combustion chamber and guides combustion light inside the combustion chamber to the outside of the combustion chamber, and the light detection member is fixed inside and attached to the wall of the combustion chamber. A flame sensor comprising a fixing member, wherein the fixing member fixes the light detection member on a side opposite to the combustion chamber side, and contacts the outer periphery of the light detection member on the combustion chamber side from the fixed part. A flame sensor characterized in that it is supported only through a vibration-preventing material. 2. The flame sensor according to claim 1, wherein the vibration preventing material is an O-ring-shaped rubber elastic material.