JPH05174269A - Ultraviolet type flame sensor - Google Patents

Abstract

PURPOSE:To reduce dispersion in an angle of visibility when mass production is performed. CONSTITUTION:A holder 14 of molding is fixed on a printed circuit board 2. A holding part 15 which holds the base part 4a of an ultraviolet detecting tube 4 is formed at one terminal of the holder 14. A placing part 16 which holds a cylindrical part 4b that is the detecting part of the ultraviolet detecting tube 4 is formed at the other terminal of the holder 14. The base part 4a of the ultraviolet detecting tube 4 is fitted in the gap of the holding part 15 of the holder 14. Since an angle between the base part 4a and the cathode 11 of the ultraviolet detecting tube 4 can be kept almost constant, the cathode 11 can be faced with the front of the sensor. Also, the ultraviolet detecting tube 4 can be fixed at a constant position by holding the cylindrical part 4b of the ultraviolet detecting tube 4 with the placing part 16 of the holder 14.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ultraviolet flame detector equipped with an ultraviolet detector tube for detecting ultraviolet rays from a flame.

[0002]

2. Description of the Related Art FIG. 7 shows an exploded perspective view of this type of ultraviolet flame detector. The printed board 2 is arranged in the base 1,
The open surface of the base 1 is fitted and fixed with the alligator cover 3.
The ultraviolet ray detecting tube 4 for detecting the ultraviolet ray from the flame is arranged with the spacer 5 interposed between the ultraviolet ray detecting tube 4 and the printed circuit board 2, and the lead wire 6 of the ultraviolet ray detecting tube 4 is soldered to the printed circuit board 2.

As shown in FIG. 8, the printed circuit board 2 has a terminal 7 soldered to the printed circuit board 2 and a screw 8 on the base 1.
It is designed to be fixed by soldering to the stopped contact spring 9. The contact spring 9 is arranged on the lower surface of the base 1, and is fastened together with the contact terminal 10 by the screw 8. By the way, the flame detection area of the ultraviolet flame detector is 2
Affected by one condition. One is the orientation of the cathode of the ultraviolet detection tube 4, and the other is the positional relationship between the ultraviolet detection tube 4 and the cover 3.

As shown in FIGS. 9 and 10, inside the ultraviolet detection tube 4, a cathode 11 is arranged on the lower side and an anode 12 is arranged on the slightly upper side. The directivity of the ultraviolet detection tube 4 is
As shown in FIG. 9, since the cathode 11 has a symmetrical shape centered on the direction perpendicular to the surface of the cathode 11, a symmetrical viewing angle cannot be obtained unless the surface of the cathode 11 faces the front. Also, FIG.
As shown in FIG. 1, if the center of the opening portion (hole into which ultraviolet rays enter) 13 of the cover 3 and the center of the ultraviolet ray detecting tube 4 are aligned, the viewing angles are symmetrical. However, as shown in FIG. 12, the center b of the ultraviolet detection tube 4 and the opening 13 of the cover 3 are
If the center B of is deviated, the left and right viewing angles become asymmetric.

[0005]

In the conventional example, only the lead wire 6 of the ultraviolet ray detecting tube 4 is used to fix it to the printed circuit board 2, so that the direction of the cathode 11 and the positional relationship with the cover 3 are determined. It cannot be fixed in the best orientation. Therefore, there is a problem that it is difficult to mass-produce products having the same viewing angle.

The present invention has been made in view of the above points, and an object of the present invention is to provide an ultraviolet flame detector for reducing the variation in the viewing angle in mass production.

[0007]

According to the present invention, an ultraviolet detecting tube for detecting ultraviolet rays from a flame is arranged in a base, and a cover having an opening corresponding to the ultraviolet detecting tube is provided on the opening surface of the base. In the covered ultraviolet flame detector, a holder for holding the detection direction of the ultraviolet detection tube substantially constant is provided.

[0008]

Since the positional relationship between the direction of the cathode of the ultraviolet ray detecting tube and the cover is fixed by the holder, it is possible to reduce the variation in the viewing angle of the sensor in mass production.

[0009]

Embodiments of the present invention will be described below with reference to the drawings. Since the overall configuration is the same as the conventional one, the part will be described in detail. As shown in FIGS. 1 and 2, the holder 14 is fixed to the printed board 2 by heat welding or screwing. A holder 15 having a U-shaped cross section is formed on one end of a holder 14 formed of a molded product.
A semicircular mounting portion 16 is formed on the other end side, and a substantially T-shaped fixing piece 17 for fixing to the printed circuit board 2 is integrally formed on the lower portion.

The flat base portion 4a of the ultraviolet ray detection tube 4 on the side of the lead wire 6 is fitted into the gap of the holding portion 15 of the holder 14. Since the holder 14 is a molded product, the holding portion 15
The gap is deformed to some extent and has a spring property, and the base portion 4a of the ultraviolet detection tube 4 is sandwiched. Here, as shown in FIG. 2, since the angle between the base portion 4a of the ultraviolet ray detection tube 4 and the cathode 11 is substantially constant, the cathode 11 can be directed to the front of the sensor.

The cylindrical portion 4b, which is the detecting portion of the ultraviolet ray detecting tube 4, is held by the mounting portion 16 of the holder 14, so that the ultraviolet ray detecting tube 4 is fixed at a fixed position of the holder 14. .. Then, the holder 14 is fixed to the printed board 2, and the printed board 2 is soldered to the base 1. Further, since the cover 3 is also fitted and fixed to the base 1, the positional relationship between the opening 13 of the cover 3 and the ultraviolet detection tube 4 is fixed.

By the way, FIG. 3 shows a sectional view of the whole of the sensor A, and arrows in the drawing show the passage of corrosive gas. First, as shown by the arrow a, the ultraviolet detection tube 4 enters through the opening 13 opened in the cover 3 to monitor the ultraviolet rays, and as shown by the arrow b, the cover 3 and the base 1 are fitted together. It enters through the gap between the joints, and further enters through the gap between the terminal 7 and the hole 18 formed in the base 1 as shown by arrow C.

When the corrosive gas enters as described above, the electronic parts and the printed circuit board 2 are corroded and the performance of the sensor A is deteriorated. Therefore, in this embodiment, a rubber packing is provided at a place where the corrosive gas enters to prevent the gas from entering. First, as shown in FIG. 4, the circumference of the ultraviolet detection tube 4 is surrounded by the rubber packing 19. Rubber packing 19
Is compressed by the printed circuit board 2 and the cover 3 to block the inside and outside of the rubber packing 19 and prevent gas from entering.

Further, as shown in FIG. 5, a rubber packing 20 is provided between the cover 3 and the base 1. Rubber packing 2
0 is compressed by fitting the base 1 and the cover 3, and shuts the inside and outside of the rubber packing 20 to prevent gas from entering. Furthermore,
As shown in FIG. 6, a rubber packing 21 with a hole in the center
The rubber packing 19 shown in FIG. 4 pushes the printed circuit board 2 downward by inserting the terminal 2 into the terminal 7 and fitting the cover 3 to the base 1. Then, the rubber packing 21 between the printed board 2 and the base 1 is compressed. Therefore, it is possible to prevent gas from entering through the hole 18 through which the terminal 7 of the base 1 is inserted.

As described above, the three kinds of rubber packings 19 to
Since the inside and outside of the sensor A is blocked by 21, the sensor A
The electronic components inside the sensor A and the printed circuit board 2 are not affected by the corrosive gas even when exposed to the corrosive gas. Therefore, the performance of the sensor A can be maintained even in corrosive gas. Although the holder 14 is not shown in FIGS. 3 to 6, it can be applied regardless of the presence or absence of the holder 14.

[0016]

As described above, according to the present invention, the ultraviolet detecting tube for detecting the ultraviolet rays from the flame is arranged in the base, and the cover having the opening corresponding to the ultraviolet detecting tube is provided on the opening surface of the base. Since the holder for holding the detection direction of the ultraviolet detection tube substantially constant is provided in the covered ultraviolet flame detector, the positional relationship between the direction of the cathode of the ultraviolet detection tube and the cover is fixed by the holder. Therefore, it is possible to reduce the variation in the viewing angle of the sensor in the case of mass production.

[Brief description of drawings]

FIG. 1 is an exploded perspective view of an embodiment of the present invention.

2 (a) and 2 (b) are a front view and a side view of the ultraviolet detection tube of the same.

FIG. 3 is a cross-sectional view of the above sensor.

4 (a) and (b) are a plan view and a cross-sectional view of a main part of the same.

FIG. 5 is a cross-sectional view of relevant parts of the same.

FIG. 6 is a cross-sectional view of an essential part of the above.

FIG. 7 is an exploded perspective view of a conventional example.

FIG. 8 is a cross-sectional view of an essential part of the above.

FIG. 9 is an explanatory diagram of an ultraviolet ray detection tube.

10A and 10B are a plan view and a side view of an ultraviolet ray detection tube.

FIG. 11 is an explanatory diagram when the viewing angle of the ultraviolet ray detection tube is symmetrical.

FIG. 12 is an explanatory diagram when the viewing angle of the ultraviolet detection tube is asymmetric.

[Explanation of symbols]

 1 Base 2 Printed Circuit Board 3 Cover 4 Ultraviolet Detecting Tube 13 Opening 14 Holder

Claims (1)

[Claims] 1. An ultraviolet flame detector in which an ultraviolet ray detecting tube for detecting ultraviolet rays from a flame is disposed in a base, and a cover having an opening corresponding to the ultraviolet ray detecting tube is provided on the opening surface of the base. The ultraviolet flame detector according to claim 1, further comprising a holder for holding the detection direction of the ultraviolet detection tube substantially constant.