JP7656464B2 - Light shielding cover for flame detector - Google Patents

Description

The present invention relates to a light-shielding cover for a flame detector that detects flames, and to a technology that is effective when used for a light-shielding cover for a flame detector that is used to temporarily disable the detection function of the flame detector when performing work that may temporarily generate sparks, such as in construction work where there is a risk of flames or sparks being generated or in steelworks.

When construction work that may generate flames or sparks is carried out in a facility where a flame detector is installed, the flame detector may detect flames or sparks generated during the construction work and erroneously report a fire. In addition, when dust-generating work such as chipping or sanding is carried out for renovation work, the smoke detector may detect the generated dust. Furthermore, even in environments other than construction work, for example, welding work that generates flames or sparks may be carried out in steelworks, and the flame detector may detect the flames or sparks generated at this time and erroneously report a fire.
Therefore, before construction begins, a vinyl cover with a rubber ring around the periphery is attached to the detector. Also, in order to make it possible to attach such a cover to a detector installed at a high place without using a stepladder or the like, an attachment tool as described in Patent Document 1 has been proposed.

Furthermore, fire detector covers, such as those described in Patent Document 2, have been proposed as a technique for preventing false detection by fire detectors due to flames or sparks generated during construction work.
The fire detector cover of Patent Document 2 has a light-shielding section that blocks infrared rays on the entire surface of a sheet-like cover material, and a luminous section and a reflective section on the surface of the cover material. A rubber mouth section is provided at the opening of the cover material as a means of attaching the cover to the fire detector, and the luminous section and reflective section are attached to the surface of the cover material with hook-and-loop fasteners.

JP 2019-16073 A JP 2020-194597 A

By attaching a cover having a rubber ring (mouth rubber) around the periphery as described in Patent Documents 1 and 2 above to the detector, it is possible to prevent the fire detector from malfunctioning.
However, when using a cover that simply has a rubber ring around the periphery as described in Patent Document 1, there is a problem in that there is a risk that the cover may be forgotten to be removed from the fire detector after installation is completed.

On the other hand, the fire detector cover described in Patent Document 2 has a phosphorescent section and a reflective section on the surface of the cover material, so that it is possible to confirm from below that the cover is attached to the fire detector. However, when the facility to be worked on is large in area and many fire detectors are installed, the worker must patrol the entire area to check, which places a heavy burden on the worker. In addition, dust generated during work may adhere to the surface of the cover, in which case it becomes difficult to visually confirm that the cover is attached from below, and there is a risk that it may be overlooked.

Furthermore, the covers described in Patent Documents 1 and 2 above are made of a flexible sheet, and therefore cannot protect the detector from debris generated during the chipping operation if the debris scatters. In addition, if the detector to be attached to prevent false detection is a flame detector, a cover made of a resin sheet cannot completely block light from the outside, and therefore there is a problem that false detection cannot be reliably prevented.
One option would be to make the entire cover out of metal, but it was found that if the cover is made of metal, it would be difficult to use the same cover when there are multiple types of detectors that need to be used, and problems would arise in that separate covers of different sizes, etc. would have to be prepared.

The present invention has been made with attention to the above-mentioned problems, and its object is to provide a light-shielding cover for a flame detector that can protect the flame detector to which it is attached and prevent erroneous detection, while being able to accommodate multiple types of flame detectors with different external shapes.
Another object of the present invention is to provide a light-shielding cover for a flame detector which can be prevented from being forgotten to be removed from the flame detector.

In order to solve the above problems, the present invention provides:
A flame detector light-shielding cover is attached to a flame detector including a detection light-receiving element that receives light of a predetermined wavelength emitted by a flame, and a housing that houses the detection light-receiving element and a flame detection circuit and has a detection window on the front side through which the detection light-receiving element faces, and is configured to cover the front of the detection window to prevent light from entering from outside,
a first fitting ring and a second fitting ring each having an opening through which the housing can be loosely inserted;
a connecting member that connects the first fitting ring and the second fitting ring in parallel with each other at a predetermined interval;
a light-shielding plate formed of an opaque and rigid material that is detachably coupled to an outer surface of the first fitting ring or the second fitting ring and closes the opening;
a fixing means for contacting an outer surface of the housing to prevent the housing from moving relative to the outer surface;
Equipped with
The opening of the first fitting ring and the opening of the second fitting ring are set to have different sizes or shapes,
A handle is provided on the front surface of the light-shielding plate,
The first fitting ring and the second fitting ring are configured to have an engagement portion that engages with a predetermined portion of the housing when the first fitting ring and the second fitting ring are attached to the flame detector.

According to a flame detector light-shielding cover having the above-described configuration, the light-shielding plate is opaque and rigid, and blocks the opening of the first mating ring or the second mating ring. Therefore, when the cover is attached to a flame detector, the detection window can be covered with the light-shielding plate, thereby protecting the detector to which it is attached and preventing erroneous detection.
In addition, by switching the light-shielding plate from the first mating ring to the second mating ring or vice versa and changing its orientation by 180 degrees, either the first mating ring or the second mating ring can be attached to the flame detector with the housing of the flame detector inserted into the opening, making it possible to accommodate multiple types of detectors with different external shapes.
Furthermore, since the light-shielding plate is provided with a handle, the light-shielding cover can be operated with one hand, so that the light-shielding cover can be attached to the flame detector relatively easily.

Here, preferably, the flame detector to be mounted includes a detection means for detecting dirt on the detection window,
A light-shielding piece is provided on the rear surface of the light-shielding plate at a position that intersects with the detection optical axis of the detection means when the light-shielding plate is attached to the flame detector.
According to this configuration, because a light-shielding piece is provided on the rear surface of the light-shielding plate, when the light-shielding cover of the present invention is attached to the flame detector, the function of detecting dirt on the detection window of the flame detector sends a dirt detection signal for the detection window to the receiver, so that the receiver can determine whether or not a light-shielding cover is attached to the flame detector. This makes it easy to find out if the light-shielding cover has been left on the flame detector, and prevents forgetting to remove the light-shielding cover.

Furthermore, preferably, an annular seal material is formed on the rear surface of the light-shielding plate around the light-shielding piece at a height sufficient to allow contact with the front member of the flame detector.
With this configuration, a ring-shaped sealing material that contacts the front member of the flame detector is provided on the rear surface of the light-shielding plate, making it possible to more reliably prevent external light from entering the interior through the detection window. This makes it possible to avoid the flame detector detecting flames or sparks that occur during construction work and erroneously reporting a fire.

Also, preferably, the fixing means is
A pair of leaf springs whose tips are capable of contacting an outer surface of the housing of the flame detector to be attached;
and a pair of stoppers that come into contact with predetermined protrusions on the housing when the flame detector is attached in the correct position.
With this configuration, the fixing means is composed of a pair of leaf springs and a stopper, so that the light-shielding cover can be attached to the housing of the flame detector in the correct position with a simple operation, and the light-shielding cover attached to the flame detector can be prevented from shifting or falling off.

Also, preferably, the flame detector to be mounted has a protruding portion formed on an outer surface of the housing into which a screw is fastened to connect the main body case and the bottom wall side of the housing,
The engagement portion is formed so as to bulge partially inwardly at the edge of the opening of each of the first and second mating rings, and is configured as a bulging portion that can enter and engage with the back side of the protruding portion when rotated.
According to this configuration, it is possible to more reliably prevent the light-shielding cover attached to the flame detector from falling off.

Furthermore, it is preferable that the front surface of the light-shielding plate be marked with a pattern that corresponds to the detection window of a flame detector when attached to the flame detector, in an orientation such that the detection window and the pattern match when attached correctly.
With this configuration, the light-shielding plate can be attached so that the pattern printed on the front surface matches the detection window of the flame detector to which it is to be attached, allowing the light-shielding cover to be easily and accurately attached to the housing of the flame detector.

The light-shielding cover for a flame detector according to the present invention can be adapted to multiple types of flame detectors with different external shapes while protecting the flame detector to which it is attached and preventing erroneous detection. It can also prevent the user from forgetting to remove the light-shielding cover from the flame detector. Another advantage is that the light-shielding cover can be attached to the flame detector relatively easily using one hand.

1A and 1B show an embodiment of a light-shielding cover for a flame detector according to the present invention, in which FIG. 1A is a perspective view of the light-shielding cover seen diagonally from the front, and FIG. 1B is a perspective view of the light-shielding cover seen diagonally from the rear. 1A is an oblique view of a flame detector equipped with a light-shielding cover according to an embodiment, in which (A) is an oblique view showing the state in which the light-shielding cover is attached to product A, and (B) is an oblique view showing the state in which the light-shielding cover is attached to product B. 1A is a perspective view showing the relative positions of parts when a light-shielding cover is attached to a product A, and FIG. 1B is a perspective view showing the relative positions of parts when a light-shielding cover is attached to a product B. FIG. 1 shows examples of two types of flame detectors, where (A) is a front view of product A and (B) is a front view of product B. FIG. 13 is an enlarged cross-sectional view of a detection portion of the flame detector, illustrating the function of a light-shielding member provided on the rear surface of the light-shielding plate. FIG. 11 is a diagram for explaining the work procedure for installing the light-shielding cover of the embodiment, in which (A) is an oblique view showing the state before the light-shielding cover is attached to the flame detector, and (B) is an oblique view showing the state after the light-shielding cover is attached to the flame detector.

Hereinafter, an embodiment of a light-shielding cover for a flame detector (hereinafter simply referred to as a light-shielding cover) according to the present invention will be described with reference to the drawings. Fig. 1(A) is a perspective view of the light-shielding cover as seen obliquely from the front, Fig. 1(B) is a perspective view of the light-shielding cover of (A) as seen obliquely from the rear, and Fig. 2 is a perspective view showing the light-shielding cover of this embodiment of Fig. 1 attached to two types of flame detectors with different specifications.
In addition, in the flame detector 30 in which the light-shielding cover 10 of this embodiment is used, as shown in Figure 4, detection light-receiving elements 31a, 31b, and 31c, each consisting of three infrared sensors (e.g., pyroelectric elements) with different detection wavelengths, are arranged side-by-side inside the housing, and in the following description, the direction in which the detection light-receiving elements 31a to 31c of the flame detector 30 face will be referred to as the front side or forward, and the opposite side will be referred to as the back side or rear.

Flame detector 30 is generally fixedly installed on the wall of a building directly or using an angle adjuster as a base with the back side facing the mounting surface, and detects flames in the area in front of the front. In Fig. 2, flame detector 30 is shown installed using an angle adjuster 40. Such a flame detector is connected by wiring to a receiver (not shown) that centrally manages multiple flame detectors in the detection area, and when it detects a flame, it transmits a detection signal to the receiver.
The front of the detection light receiving element is covered with a protective glass made of a light-transmitting material such as sapphire glass. In this specification, the opening of this protective glass is referred to as the detection window. The flame detector 30 in which the light-shielding cover 10 of this embodiment is used has a function of detecting dirt on the detection window by a pair of a light-emitting element and a light-receiving element. A flame detector having such a function is described in, for example, Japanese Patent Application Laid-Open No. 2001-283345.

1, the light-shielding cover 10 of this embodiment includes a first fitting ring 11A having a circular opening slightly larger than the housing of the flame detector 30 in FIG. 2, four connecting plates 12a to 12d fixed by welding or the like to the front surface of the first fitting ring 11A so as to protrude forward, a second fitting ring 11B having a circular opening fixed by welding or the like to the front ends of the connecting plates 12a to 12d, a disk-shaped light-shielding plate 14 detachably fixed to the second fitting ring 11B by screws 13a to 13d, and a handle (grip) 15 fixed to the front surface of the light-shielding plate 14. The light-shielding plate 14 is formed of an opaque and rigid material.
Here, the opening of the first fitting ring 11A and the opening of the second fitting ring 11B are set to different sizes in order to accommodate two types of flame detectors with different outer shapes of the housing by changing the front-to-back orientation of the light-shielding cover 10 and by switching the fitting ring to which the light-shielding plate 14 is attached.

The fitting rings 11A and 11B each have a plurality of bulging portions 11a, 11b formed at a predetermined interval at the opening thereof, which bulge inward. The bulging portions 11a, 11b are intended to prevent the light-shielding cover 10 from coming off by entering the rear side of a half-bullet-shaped fixing portion provided at the base of the housing of the flame detector 30. The function of the bulging portions 11a, 11b will be explained later.
In addition, screw holes are also formed in the portions of the first fitting ring 11A corresponding to the rear ends of the connecting plates 12a to 12d, and the light-shielding plate 14 can be removed from the second fitting ring 11B by loosening the screws 13a to 13d, and then joined to the back side of the first fitting ring 11A and coupled with the screws 13a to 13d.

Specifically, as shown in Figures 3(A) and (B), with the light-shielding plate 14 removed, the main frame of the light-shielding cover 10 is inverted so that either the engaging ring 11A or 11B faces the light-shielding plate 14, as shown by the symbol C, thereby joining the light-shielding plate 14 to the engaging ring 11A or 11B, and then the light-shielding plate 14 is ready for use by coupling it with the screws 13a to 13d.
By switching the fitting ring that joins the light-shielding plate 14 to 11A or 11B, it is possible to accommodate cases in which two types of flame detectors 30 are used, as shown in Figures 2(A) and 2(B). The flame detector 30 shown in Figure 2(A) is a waterproof product with a pressure-resistant explosion-proof structure, while the flame detector 30 shown in Figure 2(B) is a dust-proof and waterproof product that does not have a pressure-resistant explosion-proof structure.

A pair of stopper pins 16a, 16b are provided at positions 180° apart on the front surface (the surface facing the light-shielding plate 14) of the first fitting ring 11A. One of the stopper pins, 16a, is shown in Fig. 1(A), while 16b is not visible as it is hidden by the light-shielding plate 14. As shown in Fig. 1(B), a pair of stopper pins 16c, 16d are also provided at positions 180° apart on the inner surface of the second fitting ring 11B.
Furthermore, the stopper pins 16a, 16b and 16c, 16d have different colors (e.g., white and black) on their surfaces, so that it is easy to identify whether the light-shielding plate 14 is attached to the fitting ring 11A or 11B when the light-shielding cover 10 is used for either of the two types of products A or B. Instead of changing the colors of the stopper pins 16a, 16b and 16c, 16d, the leaf springs 17a, 17b and 17c, 17d or the inner surfaces of the fitting rings 11A and 11B may be changed in color, or an equipment identification symbol such as A or B may be written on them.

On the other hand, the lengths of the connecting plates 12 a to 12 d are set to be substantially the same as the height of the housing of the flame detector 30 .
1B, a pair of pressing leaf springs 17a, 17b are provided on the outer surfaces of the opposing connecting plates 12a and 12c of the connecting plates 12a to 12d on the side closer to the first fitting ring 11A, and a pair of pressing leaf springs 17c, 17d are provided on the side closer to the second fitting ring 11B (light-shielding plate 14 in the figure). These leaf springs 17a to 17d are formed so that their tips are slightly closer to the center than the base side.
Furthermore, the leaf springs 17a and 17b are disposed parallel to the first fitting ring 11A, while the leaf springs 17c and 17d are disposed inclined such that their tips are away from the light-shielding plate 14 (second fitting ring 11B).

The reason for the above configuration is that the flame detectors for which the light-shielding cover 10 of this embodiment is to be used include waterproof products with pressure-resistant explosion-proof structures and dust-proof and waterproof products without such structures. As shown in Figures 4(A) and (B), the positions of the fixing parts F1 to F4 that bulge out in a semi-bullet shape from the housing base of the flame detector 30 are different between the pressure-resistant explosion-proof product and the dust-proof and waterproof product. In the explosion-proof product of (A), the fixing parts F1 to F4 are provided at equal intervals of 90 degrees, whereas in the dust-proof and waterproof product of (B), the fixing parts F1-F2 and F1-F4 are provided at different angular intervals and the external dimensions of the housing are also different. The fixing parts F1 to F4 are provided at the rear end of the dome-shaped detector main body case that constitutes the housing as screw-on parts for connecting the disk-shaped bottom wall. The part designated by the reference numeral 36 is the front cover plate, which has an opening 36a in the center facing the detection window.

Furthermore, as shown in Figures 1(A) and (B), the leaf springs 17a to 17d are set so that their tips are located at a position a predetermined distance away from the stopper pins 16a to 16d. The distance from the tips of the leaf springs 17a to 17d to the stopper pins 16a to 16d corresponds to the width of the bullet-shaped fixing parts F1 to F4 of the housing base of the flame detector 30. More precisely, the distance from the tips of the leaf springs 17a to 17d to the stopper pins 16a to 16d is set to be slightly narrower than the width of the fixing parts F1 to F4 of the flame detector 30.

On the other hand, as shown in FIG. 1(B), a pair of positioning abutment pins 18a, 18b are fixed to each of the inner surfaces of the connecting plates 12a to 12d to position the light-shielding cover 10 so that the central axis of the flame detector 20 coincides with the central axis of the light-shielding cover 10 when the tip abuts against the surface of the housing of the flame detector 30. All of the abutment pins 18a are the same height, and all of the abutment pins 18b are also the same height, but the abutment pins 18a and 18b have different heights; one (18a) has a height set to correspond to the outer shape of product A of the two types of flame detectors A and B, and the other (18b) has a height set to correspond to the outer shape of product B.

As shown in FIG. 1B, a ring-shaped rubber seal 19 is attached to the back surface of the light-shielding plate 14, and a light-shielding member 20 having a pair of parallel light-shielding pieces 20a, 20b is fixed to the center of the seal 19. The height of the seal 19 is set to be slightly greater than the height (thickness) of the fitting rings 11A, 11B, so that when the light-shielding cover 10 is placed over the flame detector 30 as shown in FIG. 2, the seal 19 is in close contact with the periphery of the front cover plate of the flame detector 30, blocking light from the outside together with the light-shielding plate 14 and preventing it from entering the inner light-receiving elements 31a to 31c.

Furthermore, at a portion of the connecting plate 12c near the fitting ring 11, the other end (upper in the figure) of the ball chain 22, to which an openable and closable snap clip ring 21 for hanging is connected at one end (lower in the figure), is connected by a screw (not shown). The snap clip ring 21, for example, engages with a locking hole provided in the angle adjuster 40 that serves as the base, and functions together with the ball chain 22 as a means for preventing the light shielding cover 10 from falling off. The snap clip ring 21 may be a simple ring, and this ring may be connected to the locking hole provided in the angle adjuster 40 with a cable tie or the like. The angle adjuster 40 is a jig for installing the flame detector so that the detection window faces the desired direction. All of the components (11 to 19) that make up the light shielding cover 10 are made of metal such as stainless steel, but some of the components may be made of plastic.

1(A), a pattern W is printed or otherwise indicated on the center of the upper surface of the light-shielding plate 14, which is an oval corresponding to the detection window of the flame detector 30 and three small circles arranged side by side inside it, representing the detection light-receiving elements 31a to 31c. This indication serves as a guide for matching the orientation when attaching the light-shielding cover 10 to the existing flame detector 30, making the attachment operation easier.
In addition, as shown in Figure 2 (B), the peripheral portion of the upper surface of the light-shielding plate 14 is marked with an arrow Y1 (LOCK) indicating the direction (locking direction) in which the light-shielding cover 10 should be rotated when attached to the existing flame detector 30, and an arrow Y2 (OPEN) indicating the direction (opening direction) in which the light-shielding cover 10 should be rotated when removed from the flame detector 30.

FIG. 5 is a diagram for explaining the function of the light shielding member 20 provided on the rear surface of the light shielding plate 14. As shown in FIG.
As shown in Fig. 5, inside the housing of the flame detector 30 in which the light-shielding cover 10 of this embodiment is used, an LED 34 as a test light source for detecting the degree of dirt on the detection window 33, a test light-receiving element (not shown in Fig. 3), and elements constituting a determination circuit for determining dirt based on a signal from the test light-receiving element are mounted on a circuit board 32. The test light-receiving element is disposed in correspondence with a light output portion provided on a light emitting member 35 for emitting light from an LED for an operating light (not shown) to the front of the housing. In addition, another set of the test LED 34 and the test light-receiving element as described above is provided on the circuit board 32.

The two test LEDs are disposed at an angle at a position approximately 180 degrees away from the test light-receiving element, and the light emitted from one of the test LEDs 34 passes through the detection window 33, enters the tapered surface 35a of the light emitting member 35, and enters the corresponding test light-receiving element via the light-guiding member, as shown by the dashed line in Fig. 5. At this time, if the detection window 33 is dirty, the amount of test light reaching the test light-receiving element decreases, so the determination circuit on the circuit board can determine the degree of dirt on the detection window 33 based on the detection signal of the test light-receiving element.
The test light receiving element is selected to detect light in a wavelength band that includes the wavelength of the light emitted by the test LED, so that the degree of dirt on the detection window 33 can be detected even if the detector is installed in a place where there is external light.

The light-shielding pieces 20a and 20b of the light-shielding member 20 in the light-shielding cover 10 of this embodiment are provided corresponding to two sets of test LEDs 34 and test light-receiving elements, and when the light-shielding cover 10 is attached to the flame detector 30, as shown in FIG. 5, the light-shielding piece 20a faces the position intersecting with the optical axis of the test LED 34, blocking the light from the test LED 34 and preventing it from entering the test light-receiving element. As a result, the judgment circuit on the circuit board 32 judges that the window (window glass) is dirty and transmits a pseudo dirt detection signal to a receiver (not shown), which receives the signal and reports it. Therefore, even if the work is completed, if a dirt detection signal is received from the flame detector 30, it can be judged that the light-shielding cover 10 has not been removed. The judgment of whether the window is dirty or not is performed at a specific interval, for example, every 12 hours, but it may be monitored continuously.

Next, a method of attaching and detaching the light-shielding cover 10 of this embodiment to and from the flame detector 30 will be described with reference to FIG.
When attaching the light-shielding cover 10 to the flame detector 30, grasp the handle 15 and move the light-shielding cover 10 backward so that the housing of the flame detector 30 fits into the opening of the fitting ring 11A at an angle that matches the pattern W representing the detection window on the surface of the light-shielding plate 14 with the detection window of the flame detector 30, as shown in Figure 6 (A).

Then, because the bulges 11a, 11b (see FIG. 1) on the inner edge of the opening of the fitting ring 11A are angularly offset from the fixed parts F1-F4 of the housing of the flame detector 30, the light-shielding plate 14 can be inserted until the sealant 19 on the back surface of the front cover plate 36 of the flame detector 30 without interfering with F1-F4. At this time, the tips of the abutment pins 18a, 18b on the inside of the connecting plates 12a-12d abut against the surface of the housing of the flame detector 30, and the light-shielding cover 10 becomes stable.

In this state, the front surface of the fitting ring 11A is positioned on approximately the same plane as the back surface of the bottom wall of the flame detector 30. When the handle 15 is rotated counterclockwise, the bulges 11a and 11b on the inner edge of the opening of the fitting ring 11A move behind the fixing parts F1 to F4 and come into contact with the back surface of the bottom wall of the flame detector 30, preventing the light-shielding cover 10 from moving forward. The tips of the leaf springs 17a and 17b move over the fixing parts F1 and F3 of the housing of the flame detector 30. Then, just before the fixing parts F1 and F3 complete the overstepping, the fixing parts F1 and F3 hit the stopper pins 16a and 16b, and the light-shielding cover 10 stops.
6(B), the fixing parts F1, F3 are sandwiched between the leaf springs 17a, 17b and the stopper pins 16a, 16b, and the force of the springs integrates the light-shielding cover 10 with the housing of the flame detector 30. Thereafter, the snap clip ring 21, which serves as a fall-off prevention means, is engaged with an engagement hole provided in the angle adjuster 40, completing the installation work.

On the other hand, to remove the light-shielding cover 10 from the state shown in FIG. 6(B), first remove the snap clip ring 21 from the angle adjuster 40, then grab the handle 15 and rotate it in the opposite direction to the above, clockwise. Then, pull the light-shielding cover 10 toward you when the leaf springs 17a and 17b overcome the fixed parts F1 and F3 of the housing of the flame detector 30. This allows the light-shielding cover 10 to be removed from the housing of the flame detector 30. Note that FIG. 6 shows a flame detector that is pressure-resistant and explosion-proof, but for flame detectors that are not pressure-resistant and explosion-proof, the fitting ring that connects the light-shielding plate 14 is replaced by 11A instead of 11B, and the procedure is the same as above, so a description will be omitted. Note that when attaching the light-shielding cover 10, the snap clip ring 21 may be attached to the angle adjuster 40 first. Also, when removing the light-shielding cover 10, the snap clip ring 21 may be removed from the angle adjuster 40 afterwards.

As described above, the light-shielding cover 10 of this embodiment can be easily attached to and detached from the housing of the flame detector 30 with one hand, without using any tools. When the light-shielding cover 10 is attached to the housing of the flame detector 30, it is possible to prevent light from entering the detection window from the outside, and the light for detecting dirt on the window glass is blocked by the light-shielding pieces on the inside of the light-shielding plate 14, thereby generating a pseudo dirt detection signal, which is transmitted to the receiver, allowing the receiver to recognize that the light-shielding cover has been left on the receiver side.
Furthermore, since the light-shielding plate 14 with the pair of fitting rings 11A, 11B and two sets of leaf springs 17a, 17b and 17c, 17d and the handle 15 can be attached to either the fitting ring 11A or 11B, it can be used with either of two types of products with slightly different housing sizes and shapes. Therefore, even in facilities where two types of flame detectors are installed together, one type of light-shielding cover can be used.

Although the present invention has been described above based on the embodiment, the present invention is not limited to the above embodiment and can be modified as appropriate without departing from the gist of the present invention. For example, in the above embodiment, the bulges 11a and 11b are provided on the inside of the openings of the fitting rings 11A and 11B, and the bulges 11a and 11b are positioned behind the fixed portion of the housing base of the flame detector 30 to prevent the light-shielding cover 10 from coming off the flame detector 30. However, the projections provided on the fitting rings 11A and 11B may be engaged with other portions such as recesses in the housing of the flame detector 30 to prevent the light-shielding cover 10 from coming off, or a magnet may be provided on the light-shielding cover 10, and the magnetic attraction of the magnet may prevent the light-shielding cover 10 from falling off the flame detector 30.

In addition, in the above embodiment, a ring-shaped light-shielding sealant 19 is provided on the inner surface of the light-shielding plate 14, but instead of providing the sealant 19, a non-transparent sleeve may be provided to cover the periphery of the connecting plates 12a to 12d to provide light-shielding.
Furthermore, in the above embodiment, the two fitting rings 11A and 11B with openings of different sizes and shapes are connected to both ends of the connecting plates 12a to 12d, but a further fitting ring with an opening of a different size and shape than the fitting rings 11A and 11B may be prepared and configured to be replaceable with the fitting ring 11A or 11B. This makes it possible to accommodate three or more types of flame detectors with different external shapes.
Furthermore, in the above embodiment, the present invention is described as being applied to a flame detector, but some of the functions of the present invention can also be used in detectors other than flame detectors, such as smoke detectors and heat detectors.

10 Light-shielding covers 11A, 11B Fitting rings 11a, 11b Bulging portions 12a to 12d Connecting plates 13a to 13d Screws 14 Light-shielding plate 15 Handles 16a to 16d Stopper pins 17a to 17d Leaf spring (fixing means)
18a, 18b: abutment pin 19: seal material 20: light shielding member 20a, 20b: light shielding piece 21: snap clip ring (fall-off prevention means)
22 Ball chain (means for preventing falling off)
30 Flame detector 31a, 31b, 31c Light receiving element for detection 32 Circuit board 33 Detection window 34 Test LED
35 Light emitting member 36 Front cover plate (front member)
40 Angle adjuster

Claims (6)

A flame detector light-shielding cover is attached to a flame detector including a detection light-receiving element that receives light of a predetermined wavelength emitted by a flame, and a housing that houses the detection light-receiving element and a flame detection circuit and has a detection window on the front side through which the detection light-receiving element faces, and is configured to cover the front of the detection window to prevent light from entering from outside,
a first fitting ring and a second fitting ring each having an opening through which the housing can be loosely inserted;
a connecting member that connects the first fitting ring and the second fitting ring in parallel with each other at a predetermined interval;
a light-shielding plate formed of an opaque and rigid material that is detachably coupled to an outer surface of the first fitting ring or the second fitting ring and closes the opening;
a fixing means for contacting an outer surface of the housing to prevent the housing from moving relative to the outer surface;
Equipped with
The opening of the first fitting ring and the opening of the second fitting ring are set to have different sizes or shapes,
A handle is provided on the front surface of the light-shielding plate,
A light-shielding cover for a flame detector, characterized in that the first fitting ring and the second fitting ring are provided with an engagement portion that engages with a predetermined portion of the housing when attached to the flame detector. The flame detector to be mounted is provided with a detection means for detecting dirt on the detection window,
2. The light-shielding cover for a flame detector according to claim 1, wherein a light-shielding piece is provided on a rear surface of the light-shielding plate at a position that intersects with the detection optical axis of the detection means when the light-shielding plate is attached to the flame detector. The light-shielding cover for a flame detector according to claim 2, characterized in that an annular sealant is formed on the rear surface of the light-shielding plate around the light-shielding piece at a height that allows it to contact the front member of the flame detector. The fixing means is
A pair of leaf springs having tip portions capable of contacting an outer surface of the housing of the flame detector to be attached;
a pair of stoppers that come into contact with predetermined protrusions on the housing when the flame detector is attached in the correct position;
4. The light-shielding cover for a flame detector according to claim 1, characterized in that it is configured as follows: The flame detector to be mounted has a protruding portion formed on an outer surface of the housing into which a screw is fastened to connect a main body case and a bottom wall side of the housing,
A light-shielding cover for a flame detector as described in any one of claims 1 to 4, characterized in that the engagement portion is formed so as to bulge partially inward at the edge of the opening of each of the first mating ring and the second mating ring, and is a bulge portion that can enter and engage with the back side of the protruding portion when rotated. A light-shielding cover for a flame detector according to any one of claims 1 to 5, characterized in that the front surface of the light-shielding plate is marked with a pattern that corresponds to the detection window of the flame detector when attached to the flame detector, in a direction that matches the detection window when attached correctly.

Images