JP3477429B2 - Liquid leak sensor - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a leak sensor for detecting leaks leaking from containers, pipes and the like.

[0002]

2. Description of the Related Art FIG. 15 shows an example of a conventional liquid leakage sensor. For example, in this device, a bottom surface of a tray D provided under a liquid storage tank is used as a submerged surface F. The transparent member 1 is provided so as to face the surface F to be immersed. Also,
The translucent member 1 is provided with a detection surface 2 that faces the submerged surface F via a gap S, and when there is no leakage L on the submerged surface F, the light from the light projecting unit 3 is The light is totally reflected by the detection surface 2 and is received by the light receiving unit 4. When there is the liquid leak L, most of the light from the light projecting unit 3 passes through the detection surface 2 and the amount of light received by the light receiving unit 4 becomes small, whereby the occurrence of the liquid leak L is detected.

[0003]

However, in the conventional liquid leakage sensor, as shown in FIG. 15 (B), the height from the surface to be immersed F to the detection surface 2 (H in FIG. 15 (B)) or more If the leaked liquid L does not collect on the surface, the detection surface 2 cannot contact the leaked liquid L, and it took time from the occurrence of the leaked liquid to its detection.

By the way, Japanese Laid-Open Patent Publication No. 9-72820 discloses a leak sensor for detecting leak L over a wide range. This leak sensor is shown in FIG. The end face of the light-transmissive member 5 having a cylindrical shape is abutted against the water-immersed surface, and the outer peripheral surface of the light-transmissive member 5 standing upright from the water-impregnated surface is used as the detection surface 6, and the light emitted from the light projecting unit 3 is detected. The light is received by the light receiving unit 4 by being reflected at a plurality of positions along the line. When the liquid leakage L comes into contact with any one of a plurality of positions along the detection surface 6, light escapes to the outside of the light transmitting member 5 at that portion, and the amount of light received by the light receiving unit 4 becomes small, With this, the leak L is detected.

However, in this case, since the light emitted from the light projecting portion 3 is reflected by the light receiving portion 4 after being reflected a plurality of times, it is easily affected by diffused light and the S / N ratio becomes low.
In particular, when a leak having strong corrosiveness is to be detected, the transparent member 5 may be made of, for example, a fluororesin (P
FA: Tetrafluoroethylene perfluoroalkylvinyl-ethe
Although a translucent resin such as r copolymer) is used, this fluororesin (PFA) has poor light transmission and diffuses when light passes through it, so if multi-step reflection is repeated, it will pass through the reflection surface. The emitted light is significantly reduced, and the light diffusely reflected inside is increased, and the S / N ratio is significantly lowered. Therefore,
In the configuration of this publication, a fluororesin cannot be used for the translucent member and cannot be used for detecting corrosive leaks. Further, the above-mentioned publication also discloses a structure in which a plurality of light emitting / receiving parts are provided inside the light transmitting member to monitor a wide range. However, since a plurality of light emitting / receiving parts are required, the cost is high. turn into.

The present invention has been made in view of the above circumstances. A first object of the present invention is to provide a liquid leakage sensor capable of detecting liquid leakage at an early stage, and a second object thereof is to cover a wide range. The present invention is to provide a leak sensor capable of detecting a leak.

[0007]

Means for Solving the Problems and Actions / Effects <Invention of Claim 1> A leak sensor according to the invention of Claim 1 is arranged facing a submerged surface that can be submerged by a leak and A translucent member having a bottom surface facing the submerged surface via a gap, and a light projecting section for obliquely emitting light from the side opposite to the submerged surface of the translucent member toward the bottom surface , and a light receiving portion for receiving the reflected light reflected by the emitted and the bottom surface of the light projecting unit, on the basis of the amount of light received by the light receiving portion, the leakage sensor for detecting leakage, the of the translucent member On the bottom
The partial light from at least the light emitting portion is irradiated or
In the guide portion is provided gradually narrowing the gap between the object flooding surface
It has a feature where it was given .

According to the liquid leak sensor of the present invention, when the liquid leak comes into contact with the end of the gap between the bottom surface and the surface to be immersed, the liquid leaks into the narrow gap side along the guide portion. It is drawn into and spreads thinly, touching a wide area on the bottom . As described above, according to the present invention, it is possible to spread the leaked liquid over a wide area on the bottom surface , and to detect the leaked liquid early and to detect the slight leaked liquid. The surface of the guide portion through which the liquid leaks may be, for example, a slope, a curved surface, or various shapes such as a step surface that narrows in stages, but if it is a slope or a curved surface. , Liquid leakage can be drawn in more smoothly. The surface of the guide portion through which the liquid leaks may also serve as the bottom surface , or may be separate.

<Invention of Claim 2> In the invention of Claim 2, in the liquid leakage sensor according to Claim 1, the light-transmitting member is formed such that the bottom surface extends in a slender manner in a plane parallel to the water-impregnated surface. Rutotomoni, the guide portion extends along the longitudinal direction of the bottom surface, and has a feature in the width direction of the bottom surface, where it formed so as to narrow gradually the gap between the immersion face.

According to this structure, no matter which part of the bottom surface is in contact with the leaked liquid, the leaked liquid is drawn along the guide portion so as to infiltrate into the side where the gap is narrowed in the width direction of the bottom surface. Then, at the portion where the gap is narrowed, it spreads thinly along the longitudinal direction of the bottom surface and reaches the irradiated portion of the light from the light projecting portion.
As a result, it is possible to detect liquid leakage over a wide range. Moreover, the light emitting and receiving parts, be located anywhere in the longitudinal direction of the bottom surface, since it is possible to detect the leakage that reaches the desired position in the longitudinal direction of the bottom surface, as in the conventional ones, many light emitting and receiving parts It doesn't have to be provided and does not cost much.

<Invention of Claim 3> The invention of Claim 3 is characterized in that, in the liquid leakage sensor of Claim 2, the bottom surface of the translucent member has an annular shape in a plane parallel to the surface to be immersed. Have.

In this structure, since the bottom surface has an annular shape,
It is possible to deal with the case where the leaked water enters the leaked sensor from any direction.

<Invention of Claim 4> In the invention of Claim 4, in the liquid leakage sensor according to any one of Claims 1 to 3, the bottom surface of the translucent member is configured to detect the light emitted from the light projecting portion. It is characterized in that it is formed in a shape that collects light on the light receiving portion.

According to this structure, when there is no liquid leakage,
The light emitted from the light projecting section toward the bottom surface is condensed to the light receiving section, while when the bottom surface is submerged in the liquid leakage, most of the light from the light projecting section passes through the bottom surface and is collected in the light receiving section. It will not be illuminated. As a result, the difference in the amount of light received by the light receiving portion can be more clearly distinguished depending on the presence or absence of liquid leakage, and stable detection with a high S / N ratio can be performed.

<Invention of Claim 5> In the invention of claim 5, in the liquid leakage sensor according to claim 1, the translucent member is formed such that the bottom surface thereof forms a part of a spheroid. It is characterized in that the light projecting section and the light receiving section are arranged at positions corresponding to the pair of focal points on the spheroid.

With this structure, when there is no liquid leakage, the light emitted from the light projecting portion on one focal side of the spheroid is reflected by the bottom surface forming a part of the spheroid and reflected on the other focal side. It is focused on the light receiving part. On the other hand, when the bottom surface comes into contact with the leaked liquid, most of the light from the light projecting portion passes through the bottom surface and is not focused on the light receiving portion. This makes it possible to more clearly distinguish the difference in the amount of light received by the light receiving unit depending on the presence or absence of liquid leakage, and to perform stable detection with a high S / N ratio.

<Invention of Claim 6> The invention of Claim 6 is the liquid leakage sensor according to any one of Claims 1 to 5, wherein the light projecting section has an optical fiber whose one end faces the light projecting element. The light receiving portion is characterized in that it comprises the other end portion of the optical fiber whose one end faces the light receiving element.

According to this structure, by using the optical fiber, the light projecting element and the light receiving element can be separated from the leaked liquid, and the electric circuit parts related to the light projecting element and the light receiving element are protected from the infiltration of the leaked liquid. It becomes possible.

<Invention of Claim 7> According to the invention of Claim 7, in the liquid leakage sensor according to any one of Claims 1 to 6, a light projecting section is provided between the light projecting section and the light receiving section. Since the light-shielding portion for restricting the direct application of light to the light-receiving portion is provided, it is possible to prevent light from being received by the light-receiving portion on an irregular optical path and improve the S / N ratio. it can.

As the light-shielding portion, a member having no light-transmitting property may be interposed between the light-transmitting portion and the light-receiving portion, or a part of the light-shielding member may be cut off to form the light-transmitting portion and the light-receiving portion. A configuration may be adopted in which air and the bottom surface of the translucent member are formed between the section and the section.

[0021]

BEST MODE FOR CARRYING OUT THE INVENTION <First Embodiment> A liquid leakage sensor according to a first embodiment of the present invention will be described below with reference to FIGS. 1 and 2. In FIG. 1, reference numeral F denotes a surface to be submerged that can be submerged in the leaked liquid L, for example, a bottom surface of a saucer provided on the lower side of a tank for liquid storage, or a floor near a liquid pipe. Corresponds to this.

The translucent member 10 provided in the liquid leakage sensor of this embodiment is arranged so as to face the surface F to be immersed. The translucent member 10 is made of, for example, a fluororesin (PFA), and has a bottomed bottomed tubular shape. On the lower surface of the bottom wall 11 of the translucent member 10, a flat positioning portion 16 that is in surface contact with the water-immersed surface F is formed, and a detection surface 15 is formed adjacent to the flat surface of the positioning portion 16. Detection surface 15
Is inclined so as to be separated from the surface F to be infiltrated as it is separated from the positioning portion 16. Further, as a result, the detection surface 15 and the submerged surface F are not parallel to each other in the left-right direction of FIG. The detection surface 15 and the submerged surface F are parallel to each other in the direction perpendicular to the paper surface of FIG. Then, the abutment between the positioning portion 16 and the submerged surface F causes the gap S between the detection surface 15 and the submerged surface F (see FIG. 1).
(See (A)) is positioned so as to have a predetermined size.

In this embodiment, the translucent member 1
0, the detection surface 15 also serves as the “guide portion” according to the present invention, and the detection surface 15 itself is directed toward the portion to be irradiated with the light from the light projecting portion 50 described below. Submerged surface F
It is configured to gradually narrow the gap between and.

In the inner portion of the bottom wall 11 of the light transmitting member 10,
A groove 11A is formed on the side where the detection surface 15 is close to the water-immersed surface F, and the tip end portion of the light projecting optical fiber 12 is accommodated therein as the light projecting section 50 according to the present invention. And
A light projecting element (not shown) arranged on the base end side of the light projecting optical fiber 12 is driven by a drive circuit,
Light is emitted from the front end surface 12A of the second light source 2.

On the other hand, the detection surface 1 of the inner portion of the bottom wall 11
A groove 11A is also formed on the side where 5 is away from the surface F to be immersed, and the tip of the light receiving optical fiber 13 is accommodated therein as the light receiving portion 51 according to the present invention. And
The light received by the front end surface 13A of the light receiving optical fiber 13 is given to a light receiving element (not shown) arranged on the proximal end side of the optical fiber 13. The light receiving element outputs a light receiving signal according to the amount of received light, and this is compared with a predetermined reference value by, for example, a comparator provided in a receiving circuit (not shown), and the light receiving signal falls below the predetermined reference value. The leak L is detected with.

The optical fibers 12 and 13 are positioned in such a manner that their optical axes obliquely extending from their tip surfaces 12A and 13A toward the detection surface 15 intersect at a predetermined position on the detection surface 15. The resin is fixed by the fixing resin 14 filled in the translucent member 10. More specifically, the projection angle of light from the light projecting optical fiber 12 to the detection surface 15 is equal to or greater than the critical angle when air is in contact with the detection surface 15 of the translucent member 10, and the leak liquid L is present on the detection surface 15. It is below the critical angle when in contact. The projection angle may be set so that there is a difference in reflectance when air or liquid L is in contact with the detection surface 15, and the projection angle may be set to, for example, the detection surface 15.
The angle may be equal to or less than the critical angle when is in contact with air.

Next, the operation of this embodiment will be described. When there is no leak L on the submerged surface F, the detection surface 15 is in contact with air, and the light emitted from the light projecting unit 50 (specifically, the front end surface 12A of the light projecting optical fiber 12) is detected. 1
The light is totally reflected at 5, and is received by the light receiving portion 51 (specifically, the front end surface 13A of the light receiving optical fiber 13).

On the other hand, liquid leakage occurs and the liquid L leaks to the detection surface 15.
Most of the light emitted from the light projecting unit 50 passes through the detection surface 15 and is hardly received by the light receiving unit 51. Then, the light receiving optical fiber 13 of the light receiving unit 51
The light receiving signal from the light receiving element that receives the light via the signal becomes small and falls below a predetermined reference value, whereby the leak L is detected. Here, the light transmitted through the detection surface 15 can be reflected by the submerged surface F, but in the present embodiment, the detection surface 15 and the submerged surface F are made non-parallel, and therefore, as shown in FIG. Figure 1
As shown in contrast to (B), the reflected light on the submerged surface F is directed in a different direction from the reflected light on the detection surface 15, and the amount of light received by the light receiving unit 51 depending on the presence or absence of the liquid leakage L is clear. Different to As a result, stable detection with a high S / N ratio can be performed.

Now, according to the configuration of the present embodiment, FIG.
As shown in (A), when a slight leak L contacts the end of the gap S between the detection surface 15 and the submerged surface F on the side away from the positioning portion 16, the leak L is detected. Along the inclination of the surface 15, it is drawn in so as to penetrate into the narrow side of the gap S, spreads thinly, and contacts a wide area of the detection surface 15. This allows
It is possible to detect the leak L at an early stage and detect a slight leak L.

Further, in the present embodiment, the light emitting / receiving section 50,
By using the optical fibers 12 and 13 for 51, the light projecting / receiving element can be separated from the liquid leak L, and the electric circuit portion including these light projecting / light receiving elements can be protected from the immersion of the liquid leak L.

<Second Embodiment> The liquid leakage sensor according to this embodiment is shown in FIGS. 3 to 5, and the shape of the detection surface is different from that of the first embodiment. Hereinafter, the same configurations as those of the first embodiment will be denoted by the same reference numerals, duplicate description will be omitted, and only different portions will be described.

As shown in FIG. 3, the translucent member 20 provided in the liquid leakage sensor of this embodiment has both optical fibers 12, 13 as shown in FIG.
Has a flat shape that is long in the arrangement direction and short in the direction orthogonal thereto, and the outer surface of the bottom wall 21 of the translucent member 20 is formed so as to form a part of the cylindrical outer peripheral surface (so-called cylindrical surface). (See especially Figure 5). Then, the lowermost end of the bottom wall 21 forms a positioning portion 26 and is abutted against the surface F to be submerged. Further, both sides of the positioning portion 26 form detection surfaces 25, and a gap S (see FIG.
(See (A)). Further, in the present embodiment, the tip surfaces 12A, 1 of both optical fibers 12, 13 are
3A is arranged on the central axis of the outer peripheral surface of the cylinder (see reference numeral P3 in FIG. 5). Note that, also in this embodiment,
As is apparent from the above structure, the detection surface 25 of the translucent member 20 also serves as the “guide portion” according to the present invention, as in the first embodiment.

According to the configuration of this embodiment, when there is no liquid leakage L, the light emitted from the light projecting section 50 (see FIG. 4) toward the detection surface 25 is as shown in FIG. 5 (A). , The light receiving section 51 (specifically, the tip surface 13 of the light receiving optical fiber 13)
It is focused on A). On the other hand, when the detection surface 25 is flooded with the leaked liquid L, most of the light from the light projecting unit 50 passes through the detection surface 25 and is not focused on the light receiving unit 51, as shown in FIG. 5B. . As a result, depending on the presence or absence of the leak L, the light receiving unit 5
The difference in the amount of received light of 1 is more clearly distinguished, and stable detection with a high S / N ratio can be performed.

Moreover, since the detection surface 25 is elongated and curved so as to approach the surface F to be submerged in the width direction, no matter which part of the detection surface 25 in the longitudinal direction the leaked liquid L contacts, The leaked liquid L moves so as to penetrate into the side of the detection surface 25 in which the gap S is narrowed in the width direction, and the gap S
Is spread along the longitudinal direction of the detection surface 25 at the narrowed portion, reaches the irradiated portion of the light from the light projecting portion 50, and is detected. As a result, it is possible to detect the leak L over a wide range. Moreover, no matter where the light projecting / receiving sections 50, 51 are arranged in the longitudinal direction of the detection surface 25, the liquid leakage L that has reached any position in the longitudinal direction of the detection surface 25 can be detected. There is no need to provide a lot of light emitting and receiving parts like the ones, and the cost is low.

<Third Embodiment> As shown in FIG. 6, the liquid leakage sensor of the present embodiment has a structure in which the light projecting portion 50 is directly connected to the light receiving portion 51 inside the light transmitting member 20 described in the second embodiment. A light-shielding portion 22 is provided for restricting the application of light to the. More specifically, the light-shielding portion 22 is made of a member that does not transmit light, and has a cross section in the shape of a baseball home base. , 13A in a protruding state and fixed by a fixing resin 14. As described above, in the present embodiment, by providing the light shielding portion 22, it is possible to prevent light from being received by the light receiving portion 51 from the light emitting portion 50 in an irregular optical path, and S
The / N ratio can be improved.

<Fourth Embodiment> This embodiment is the same as the third embodiment.
It is a modification of the embodiment. Light-shielding section 2 in this embodiment
As shown in FIG. 7, the reference numeral 3 designates the bottom wall 21 of the translucent member 20 from the light projecting portion 50 to the front end face 1 of the light receiving optical fiber 13.
A groove having a V-shaped cross section is formed between the groove and 3A. According to this configuration, the front end surface 12 of the light projecting optical fiber 12 is
The front end face 13A of the light receiving optical fiber 13 straight from A
The light heading for the light is refracted when passing through the inclined wall surface of the light shielding portion 23, and the front end surface 13A of the light receiving optical fiber 13 is reflected.
Since it goes to a portion different from the above, it is possible to prevent light from being received by the light receiving section 51 in an irregular optical path, and to improve the S / N ratio, as in the third embodiment.

<Fifth Embodiment> The liquid leakage sensor according to the present embodiment is shown in FIGS. 8 and 9, and the shape of the detection surface is mainly different from that of the first embodiment. Hereinafter, the same configurations as those of the first embodiment will be denoted by the same reference numerals, duplicate description will be omitted, and only different portions will be described.

The transparent member 30 of this embodiment has a bottom wall 3
The central portion of the outer surface of 1 projects toward the submerged surface F, and the tip curved surface of the projecting portion is formed so as to form a part of a spheroid, as shown in FIGS. 8 and 9.
The tip bend forms the detection surface 35, and the contact point between the tip curved surface and the submerged surface F forms the positioning portion 36. Further, around the detection surface 35, a guide portion 37 is formed which is continuous with the detection surface 35 and is inclined so that the gap S between the surface to be submerged F gradually increases as the distance from the detection surface 35 increases. Furthermore, the tip surfaces 12 of both optical fibers 12 and 13
A and 13A are a pair of focal points of the above-mentioned spheroid (see FIG. 8).
(See P1 and P2).

Although FIG. 8 shows a sectional view of the light transmitting member 30 along the parallel direction of both the optical fibers 12 and 13, the shape of the detection surface 35 is clarified in FIG. Therefore, the fixing resin 14 and the like described in the first embodiment are omitted, and only the outer edge portion of the translucent member 30 is shown.

According to this embodiment, when there is no leakage L, the light emitted from the light projecting portion 50 (the tip surface 12A of the optical fiber 12 for projection) on one side of the spheroidal ellipsoidal surface is spheroidal. It is reflected by and is condensed on the light receiving section 51 (the front end surface 13A of the light receiving optical fiber 13) on the other focal side. On the other hand, when a small amount of leaked liquid comes into contact with the outer edge of the guide portion 37, the leaked liquid L smoothly moves to the detection surface 35 side along the guide portion 37. When the detection surface 35 comes into contact with the leaked liquid L, most of the light from the light projecting section 50 passes through the detection surface 35 and the light receiving section 51.
Will not be focused on. As a result, the difference in the amount of light received by the light receiving unit 51 is more clearly distinguished depending on the presence or absence of the liquid leakage L, and stable detection with a high S / N ratio can be performed.

<Sixth Embodiment> As shown in FIG. 10, the light-transmitting member 40 provided in the liquid leakage sensor according to the present embodiment is disc-shaped and has a columnar body 49 (fixed in the first embodiment). (Corresponding to the resin 14 for use) is integrally provided at the lower end. A ridge 40B is formed on the lower surface of the translucent member 40 by projecting the outer edge thereof toward the water-immersed surface F, and a notch 48 is formed so as to cross one location of the ridge 40B.

The ridge 40B is, as shown in FIG.
The outer surface is formed so as to form a part of the outer peripheral surface of the cylinder (so-called cylindrical surface). And that ridge 4
The lowermost end portion of 0B forms a positioning portion 46, and the submerged surface F
Is struck by. Further, both sides of the positioning portion 26 form a detection surface 45 and face the submerged surface F via a gap S. Further, both the optical fibers for projecting and receiving light (only the optical fiber 13 for receiving light is shown in FIG. 11) are arranged with their tip surfaces on the axis center of the outer peripheral surface of the cylinder, and the intermediate portion penetrates the cylinder body 49. And is fixed. The irradiated portion of the light from the light projecting optical fiber is arranged, for example, at a position 180 degrees apart from the notch 48 on the detection surface 45.

Also in this embodiment, as is apparent from the above structure, as in the first and second embodiments,
The detection surface 45 of the translucent member 40 also serves as the “guide portion” according to the present invention.

In the leak sensor of this embodiment, when the leak L spreads along the detection surface 45 so as to spread, it cannot move beyond the notch 48 provided in the detection surface 45. It penetrates more widely on the side away from the notch 48. As a result, no matter which position on the detection surface 45 the leaked liquid L enters, the leaked liquid L reaches the position on the detection surface 45 that is 180 degrees away from the notch 48 early and reliably. Since the irradiated portion of the light from the light projecting optical fiber is arranged at this position, the leak L can be detected early.
Further, since the detection surface 45 is formed in an annular shape, it is possible to deal with the case where the leaked liquid L enters the leaked sensor from any direction. Further, since the positioning portion 46 also has an annular shape, the positioning stability is good. Besides, notch 48
By this, the inner side and the outer side communicate with the annular protrusion 40B,
Even if the air thermally expands inward, it can escape through the notch 48.

<Other Embodiments> The present invention is not limited to the embodiments. For example, the embodiments described below are also included in the technical scope of the present invention. Various modifications can be made without departing from the scope of the invention.

(1) In the second embodiment and the sixth embodiment, the detection surface is formed by a part of the cylindrical surface, but as shown in FIG. 12, a part of the outer peripheral surface of the elliptic cylinder is formed. The detection surface 60 is composed of the two focal points P1 and P2 of the ellipse.
Alternatively, the tip surfaces 12A and 13A of the both optical fibers 12 and 13 may be arranged.

(2) In each of the above embodiments, the detection surface is inclined or curved with respect to the surface to be immersed . The technique of the present invention
Although not included in the surgical scope
13 is shown in FIG. That is, this one has the detection surface 60 parallel to the surface F to be submerged and the detection surface 6
The guide portions 61, 61 are provided on both sides of 0, and the guide portions 61
However, it is configured so as to be inclined so as to be further away from the surface F to be immersed as the distance from the detection surface 60 increases.

(3) In each of the above embodiments, the guide portion is integrally formed with the light transmitting member, but the guide portion may be formed as a member different from the light transmitting member and attached to the light transmitting member. Good.

(4) Further, in each of the above embodiments, the positioning portion is also integrally formed with the light transmitting member, but the positioning portion is also formed by a member different from the light transmitting member and is fixed to the light transmitting member. It may be configured. The technical scope of the present invention
Although not included in Fig. 13, Fig. 13 is shown as a reference example of the above configuration.
You That is, in this compound, are as the light-transmitting member 63 to form a prismatic positioning portion 62, 62 with separate members, and fixing the positioning unit 62 on both sides of the translucent member 63 configuration.

(5) Furthermore, the positioning portion does not necessarily have to be configured to abut against the surface to be submerged. For example,
As shown in FIG. 14, the positioning portion 65 is fixed to the wall portion 64 standing upright from the submerged surface F with, for example, a screw T so that the detection surface 68 of the translucent member 67 and the submerged surface F are separated by a gap S. The configuration may be such that they are positioned so as to face each other.

[Brief description of drawings]

FIG. 1 is a sectional view of a liquid leakage sensor according to a first embodiment of the present invention.

FIG. 2 is a partially enlarged cross-sectional view of the leak sensor as well.

FIG. 3 is a perspective view of a liquid leakage sensor according to a second embodiment.

4 is a cross-sectional view of the leak sensor taken along the line AA in FIG.

5 is a cross-sectional view of the leak sensor taken along the line BB in FIG.

FIG. 6 is a sectional view of a leak sensor according to a third embodiment.

FIG. 7 is a sectional view of a liquid leakage sensor according to a fourth embodiment.

FIG. 8 is a sectional view of a leak sensor according to a fifth embodiment.

FIG. 9 is a sectional view of the leak sensor in the width direction.

FIG. 10 is a perspective view of a liquid leakage sensor according to a sixth embodiment.

FIG. 11 is a partial sectional view of the leak sensor.

FIG. 12 is a sectional view of a liquid leakage sensor showing a first modification.

FIG. 13 is a sectional view of a liquid leakage sensor showing a second modification.

FIG. 14 is a sectional view of a liquid leakage sensor showing a third modification.

FIG. 15 is a sectional view of a conventional leak sensor.

FIG. 16 is a sectional view of a conventional leak sensor.

[Explanation of symbols]

10, 20, 30, 40, 64 ... Translucent member 12 ... Optical fiber for projecting light 13 ... Optical fiber for receiving light 14 ... Fixing resin 15, 25, 35, 45, 60, 62, 63 ... Detection surface 16, 26, 36, 46, 65 ... Positioning unit 22, 23 ... Shading section 37, 61 ... Guide 50 ... Projector 51 ... Light receiving part F ... Submerged surface L ... Leakage S ... gap

Claims (7)

(57) [Claims] 1. A translucent member which is disposed so as to face a submerged surface that can be submerged in a leaked liquid and has a bottom surface which faces the submerged surface with a gap therebetween, and the one of the translucent members. comprising a light projecting portion that emits light obliquely toward the bottom surface <br/> from the opposite side of the flood plane, and a light receiving portion for receiving the reflected light reflected by and having the bottom surface is emitted from the light projecting portion Te, based on the amount of light received by the light receiving portion, the leakage sensor for detecting a leakage, the bottom surface of the light transmitting member, to the portion where the light is irradiated from at least the light emitting portion, wherein the flooding surface A liquid leakage sensor, characterized in that a guide portion is provided which gradually narrows the gap between and. 2. The translucent member is formed such that the bottom surface is elongated in a plane parallel to the surface to be submerged, and the guide portion extends along the longitudinal direction of the bottom surface .
Further, it is formed so as to gradually narrow a gap with the surface to be submerged in the width direction of the bottom surface.
The leak sensor described. 3. The bottom surface of the translucent member has an annular shape in a plane parallel to the surface to be submerged.
The leak sensor described. 4. The light transmitting member according to claim 1, wherein the bottom surface is formed in a shape that collects the light emitted from the light projecting unit onto the light receiving unit. The leak sensor described in. 5. The translucent member is formed such that the bottom surface thereof forms a part of a spheroidal surface, and the light projecting portion and the light receiving portion are provided at positions corresponding to a pair of focal points of the spheroidal surface. The leak sensor according to claim 1, wherein the leak sensor is provided. 6. The light projecting unit comprises the other end of the optical fiber whose one end faces the light projecting element, and the light receiving unit comprises the other end of the optical fiber whose one end faces the light receiving element. The liquid leakage sensor according to any one of claims 1 to 5, which is characterized in that. 7. A light-shielding portion is provided between the light-projecting portion and the light-receiving portion, the light-shielding portion being for restricting direct application of light from the light-emitting portion to the light-receiving portion. Claim 1
7. The liquid leakage sensor according to any one of to 6.