JP2001337005A - Liquid leak sensor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a liquid leak sensor capable of detecting liquid leak early and widely. SOLUTION: The bottom wall 21 of a transparent member 20 provided with a liquid sensor is formed so that the outer surface shapes a part of the cylindrical surface. The bottommost of the bottom wall 21 shapes the positioning part 26 and both sides of the positioning part 26 shapes a detection surface 25. The detection surface 25 extends thin and long and bends approaching toward a submerging part F in the width direction. So, even if the leaked liquid L contacts any part of the detection surface 25 in the longitudinal direction, the leaked liquid L moves to the narrowing side of a gap S in the width direction of the detection surface 25, spreads in the narrowing part of the gap S along the longitudinal direction and reaches a part illuminated by a floodlight 50 to be detected. With this method, the detection of leaked liquid L is made possible in wide range.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

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

[0002]

2. Description of the Related Art FIG. 15 shows an example of a conventional liquid leak sensor. For example, a liquid leak sensor having a bottom surface of a receiving tray D provided on the lower side of a liquid storage tank is designated as a surface F to be immersed. The light-transmitting member 1 is provided so as to face the immersion surface F. Also,
The light transmitting member 1 is formed with a detection surface 2 facing the water immersion surface F via the gap S. When there is no liquid leakage L on the water immersion surface F, the light from the light projection unit 3 The light is totally reflected by the detection surface 2 and received by the light receiving unit 4. If there is a 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 generation 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 immersion surface F to the detection surface 2 (H in FIG. 15 (B)) or more. If the leaked liquid L does not accumulate, the detection surface 2 cannot come into contact with the leaked liquid L, and it takes time from the occurrence of the leaked liquid to the detection thereof.

Japanese Patent Application Laid-Open No. 9-72820 discloses a liquid leak sensor for detecting a liquid leak L over a wide range. As shown in FIG. The end surface of the light transmitting member 5 having a columnar shape abuts against the surface to be immersed, and the outer peripheral surface of the light transmitting member 5 rising from the surface to be immersed is defined as a detection surface 6. The light is reflected at a plurality of positions along the line and is received by the light receiving unit 4. When the leaked liquid 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 decreases. With this, the liquid L is detected.

However, in this case, since the light emitted from the light projecting section 3 is reflected by the light receiving section 4 after being reflected a plurality of times, the light is easily affected by the diffused light and the S / N ratio is lowered.
In particular, when a highly corrosive liquid leak is detected, the light transmitting member 5 is made of, for example, fluororesin (P
FA: Tetrafluoroethylene perfluoroalkylvinyl-ethe
transpolymer) is used, but this fluororesin (PFA) has poor light transmission and diffuses when light passes through it. The light that has been reflected is significantly reduced, and the light that is 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 light transmitting member, and it cannot be used for detecting corrosive liquid leakage. The above publication also discloses a structure in which a plurality of light emitting and receiving units are provided inside the light transmitting member to perform monitoring over a wide range. turn into.

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

[0007]

Means for Solving the Problems and Functions / Effects <Invention of Claim 1> The liquid leakage sensor according to the invention of Claim 1 is disposed opposite to a surface to be immersed in the liquid, and is immersed in the liquid. A light-transmitting member having a detection surface facing the surface with a gap therebetween; a light-emitting unit that emits light obliquely from the opposite side of the water-impregnated surface to the detection surface; A light-receiving unit that receives reflected light emitted from the unit and reflected by the detection surface, and detects liquid leakage based on the amount of light received by the light-receiving unit. It is characterized in that a guide portion for gradually narrowing a gap with a surface to be immersed is provided toward a portion to be irradiated with water.

According to the liquid leakage sensor of the present invention, when the liquid leaks into contact with the edge of the gap between the detection surface and the surface to be immersed, the liquid leaks along the guide portion into the narrow side of the gap. As described above, it spreads thinly and contacts a wide area of the detection surface. in this way,
ADVANTAGE OF THE INVENTION According to this invention, a leak is spread over a wide range of a detection surface, and early detection of a leak and detection of a slight leak are attained. In addition, the surface of the guide portion through which the liquid leaks is, for example, a slope, or a curved surface, and may have various shapes such as a stepped surface that gradually narrows. In addition, the liquid is drawn in more smoothly. Further, the surface of the guide portion through which the liquid leaks may be used also as the detection surface, or may be separate.

According to a second aspect of the present invention, in the liquid leakage sensor according to the first aspect, the light transmitting member is formed such that the detection surface extends elongated in a plane parallel to the surface to be immersed. In addition, the guide portion is characterized in that it extends along the longitudinal direction of the detection surface and is formed so as to gradually narrow the gap between the detection surface and the flooded surface in the width direction of the detection surface.

According to this configuration, no matter which part of the detection surface is in contact with the liquid, the liquid leaks along the guide portion into the side where the gap is narrowed in the width direction of the detection surface. At the portion where the gap becomes narrower and spreads thinly along the longitudinal direction of the detection surface, and reaches the portion to be irradiated with light from the light projecting portion. Thereby, it is possible to detect the liquid leakage over a wide range. Moreover, no matter where the light emitting / receiving part is arranged in the longitudinal direction of the detection surface, it is possible to detect a liquid leak that has reached an arbitrary position in the longitudinal direction of the detection surface.
There is no need to provide a large number of light emitting and receiving units, and there is no cost.

According to a third aspect of the present invention, in the liquid leakage sensor according to the second aspect, the detection surface of the light transmitting member is formed in an annular shape in a plane parallel to the surface to be immersed. Having.

In this configuration, since the detection surface has an annular shape, it is possible to cope with a case where the liquid leaks from the liquid sensor from any direction.

According to a fourth aspect of the present invention, in the liquid leakage sensor according to any one of the first to third aspects, the light-transmitting member has a detection surface whose light is emitted from the light projecting portion. Is formed in a shape that condenses light on the light receiving portion.

According to this configuration, when there is no liquid leakage,
The light emitted from the light-emitting part toward the detection surface is condensed to the light-receiving part, but when the detection surface is immersed in liquid leakage, most of the light from the light-emitting part passes through the detection surface and is received. No light is collected on the part. Thereby, the difference in the amount of light received by the light receiving unit is more clearly distinguished depending on the presence or absence of liquid leakage, and stable detection with a high S / N ratio can be performed.

According to a fifth aspect of the present invention, in the liquid leakage sensor according to the first aspect, the light-transmitting member includes:
The detection surface is formed in a shape that forms a part of the spheroidal surface, and is characterized in that the light projecting unit and the light receiving unit are arranged at positions corresponding to a pair of focal points of the spheroidal surface.

In this configuration, when there is no liquid leakage, the light emitted from the light projecting portion on one focal side of the spheroidal surface is reflected by the detection surface forming a part of the spheroidal surface and is reflected on the other focal side. Is collected on the light receiving section of On the other hand, when the detection surface comes into contact with the liquid leak, most of the light from the light projecting portion passes through the detection surface and is not collected on the light receiving portion. Thereby, the difference in the amount of light received by the light receiving unit is 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 6> According to the invention of claim 6, in the liquid leakage sensor according to any one of claims 1 to 5, the light projecting unit has an optical fiber having one end facing the light projecting element. The light receiving section is characterized by being formed by the other end of an optical fiber having one end facing the light receiving element.

According to this configuration, by using the optical fiber, the light projecting element and the light receiving element can be separated from the liquid leakage, and the electric circuit portion relating to the light projecting element and the light receiving element is protected from the water leak. It becomes possible.

<Seventh Invention> According to a seventh aspect of the present invention, in the liquid leakage sensor according to any one of the first to sixth aspects, a light emitting unit is provided between the light emitting unit and the light receiving unit. A light-blocking portion is provided to restrict the light from being directly applied to the light-receiving portion, so that light is not received by the light-receiving portion through an irregular optical path, and the S / N ratio can be improved. it can.

The light-shielding portion may have a structure in which a member having no light-transmitting property is interposed between the light-emitting portion and the light-receiving portion. A configuration in which a detection surface of the air and the light transmitting member is formed between the first and second portions.

[0021]

DESCRIPTION OF THE PREFERRED EMBODIMENTS <First Embodiment> Hereinafter, a liquid leakage sensor according to a first embodiment of the present invention will be described with reference to FIGS. In FIG. 1, reference symbol F denotes a surface to be submerged which can be submerged by the leaked liquid L. For example, a bottom surface of a tray provided below a tank for storing liquid, a floor near a liquid pipe, or the like is used. This corresponds to this.

The light transmitting member 10 provided in the liquid leakage sensor of the present embodiment is disposed to face the surface F to be immersed. The translucent member 10 is made of, for example, a fluororesin (PFA) and has a cylindrical shape with a bottom end. On the lower surface of the bottom wall 11 of the light transmitting member 10, a flat positioning portion 16 that is in surface contact with the surface to be immersed F is formed, and a detection surface 15 is formed adjacent to the flat surface of the positioning portion 16. Detection surface 15
Are inclined so as to be further away from the flooded surface F as the distance from the positioning section 16 increases. In addition, the detection surface 15 and the flooded surface F are thus non-parallel in the left-right direction of FIG. Note that, in a direction perpendicular to the paper surface in FIG. 1A, the detection surface 15 and the flooded surface F are parallel. Then, the gap S between the detection surface 15 and the flooded surface F (FIG. 1)
(A) is positioned so as to have a predetermined size.

In this embodiment, the light transmitting member 1 is used.
0, the detection surface 15 also serves as a “guide unit” according to the present invention, and the detection surface 15 itself is directed toward a portion of the detection surface 15 to be irradiated with light from the light emitting unit 50 described below. Submerged surface F
Is gradually narrowed.

In the inner part 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 closer to the surface F to be immersed, and the tip of the light emitting optical fiber 12 is accommodated therein as the light projecting unit 50 according to the present invention. And
A light emitting element (not shown) arranged on the base end side of the light emitting optical fiber 12 is driven by a driving circuit, and the light emitting optical fiber 1
Light is emitted from the front end face 12A of the second.

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 immersion surface F, 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 on the distal end face 13A of the light receiving optical fiber 13 is given to a light receiving element (not shown) arranged on the base end side of the optical fiber 13. The light receiving element outputs a light receiving signal corresponding to the amount of light received, 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. Then, the liquid L is detected.

The two optical fibers 12 and 13 are positioned so that the two optical axes extending obliquely from the tip surfaces 12A and 13A toward the detection surface 15 intersect at a predetermined position on the detection surface 15. The light transmitting member 10 is fixed by a fixing resin 14 filled therein. More specifically, the light 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 light transmitting member 10, and the liquid L leaks to the detection surface 15. It is less than the critical angle when in contact. Note that the projection angle may be set so long as a difference in reflectance occurs when air or liquid L is in contact with the detection surface 15.
May be equal to or smaller than the critical angle when the member is in contact with air.

Next, the operation of the present embodiment will be described. When there is no liquid leakage L on the surface F to be immersed, the detection surface 15 comes into contact with air, and the light emitted from the light projecting unit 50 (specifically, the distal end surface 12A of the light emitting optical fiber 12) is used as the detection surface. 1
5, the light is totally reflected and received by the light receiving section 51 (specifically, the distal end face 13A of the light receiving optical fiber 13).

On the other hand, a liquid leak occurs and the liquid L
, 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 section 51
The light receiving signal from the light receiving element which has received the light via the light receiving element becomes smaller than a predetermined reference value, whereby the liquid leakage L is detected. Here, the light transmitted through the detection surface 15 can be reflected by the flooded surface F. However, in this embodiment, since the detection surface 15 and the flooded surface F are not parallel, FIG. FIG.
As shown in comparison with (B), the light reflected on the surface F to be immersed is directed in a direction different from the light reflected on the detection surface 15, and the amount of light received by the light receiving unit 51 due to the presence or absence of the liquid L is clear. Different. As a result, stable detection with a high S / N ratio can be performed.

Now, according to the configuration of this embodiment, FIG.
As shown in (A), when a small amount of liquid L comes into contact with the end of the gap S between the detection surface 15 and the surface F to be immersed away from the positioning portion 16, the liquid L is detected. Along the slope of the surface 15, it is drawn so as to penetrate into the narrow side of the gap S and spreads thinly, and contacts the wide area of the detection surface 15. This allows
Early detection of the leaked liquid L and detection of a slight leaked liquid L become possible.

Further, in the present embodiment, the light emitting and receiving unit 50,
By using the optical fibers 12 and 13 for 51, the light emitting and receiving elements can be separated from the liquid leakage L, and the electric circuit portion including these light emitting and receiving elements can be protected from the infiltration of the liquid leakage L.

<Second Embodiment> A liquid leakage sensor according to the present 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 components as those in the first embodiment are denoted by the same reference numerals, and redundant description will be omitted. Only different portions will be described.

As shown in FIG. 3, the light transmitting member 20 provided in the liquid leak sensor according to the present embodiment has two optical fibers 12 and 13.
The bottom wall 21 of the light transmitting member 20 is formed so that its outer surface forms a part of a cylindrical outer peripheral surface (a so-called cylindrical surface). (Particularly, see FIG. 5). Then, the lowermost end of the bottom wall 21 forms a positioning portion 26 and is abutted against the surface F to be immersed. Further, both sides of the positioning portion 26 form a detection surface 25, and a gap S (see FIG.
(See (A)). Further, in the present embodiment, the tip surfaces 12A, 1A of the two optical fibers 12, 13 are provided.
3A is arranged on the central axis (see reference numeral P3 in FIG. 5) of the outer peripheral surface of the cylinder. In this embodiment,
As is clear from the above structure, the detection surface 25 of the light transmitting member 20 also functions as the “guide unit” according to the present invention, as in the first embodiment.

According to the configuration of the present embodiment, when there is no liquid leakage L, the light emitted from the light projecting unit 50 (see FIG. 4) toward the detection surface 25 as shown in FIG. , The light receiving portion 51 (specifically, the distal end surface 13 of the light receiving optical fiber 13)
Light is collected to A). On the other hand, when the detection surface 25 is immersed in the leaked liquid L, most of the light from the light projecting unit 50 passes through the detection surface 25 and is not collected on the light receiving unit 51 as shown in FIG. . Thereby, the light receiving unit 5 is determined depending on the presence or absence of the liquid L.
The difference in the amount of received light of 1 can be more clearly distinguished, and stable detection with a high S / N ratio can be performed.

Further, since the detection surface 25 is elongated and curved so as to approach the immersion surface F in the width direction, even if the liquid L contacts any part of the detection surface 25 in the longitudinal direction, The leaked liquid L moves so as to penetrate into the side where the gap S is narrowed in the width direction of the detection surface 25 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 unit 50, and is detected. Thereby, it is possible to detect the liquid leakage L over a wide range. In addition, no matter where the light emitting / receiving sections 50 and 51 are arranged in the longitudinal direction of the detection surface 25, the liquid leakage L that has reached an arbitrary position in the longitudinal direction of the detection surface 25 can be detected. Unlike a device, it is not necessary to provide many light emitting and receiving units, and the cost is not increased.

<Third Embodiment> As shown in FIG. 6, the liquid leakage sensor according to the present embodiment is arranged such that a light projecting portion 50 is directly connected to a light receiving portion 51 inside the light transmitting member 20 described in the second embodiment. And a light-shielding portion 22 for restricting light from being applied to the light-emitting device. More specifically, the light-shielding portion 22 is formed of a member that does not transmit light, and has a cross section of a baseball baseball shape, and the acute-angled corner portion is formed at the distal end surface 12A of the optical fibers 12 and 13. , 13A, and is fixed by a fixing resin 14 so as to protrude. As described above, in the present embodiment, the provision of the light shielding unit 22 prevents light from being received from the light projecting unit 50 to the light receiving unit 51 through an irregular optical path.
/ N ratio can be improved.

<Fourth Embodiment> The present embodiment relates to the third embodiment.
It is a modification of the embodiment. Light shielding unit 2 in the present embodiment
3 is a front surface 1 of the light receiving optical fiber 13 from the light projecting portion 50 of the bottom wall 21 of the light transmitting member 20 as shown in FIG.
3A, it is formed in a groove shape having a V-shaped cross section. According to this configuration, the distal end surface 12 of the light projecting optical fiber 12
Tip surface 13A of light receiving optical fiber 13 straight from A
Is refracted when passing through the inclined wall surface of the light shielding portion 23, and the distal end surface 13 </ b> A of the light receiving optical fiber 13.
Therefore, as in the third embodiment, light is prevented from being received by the light receiving unit 51 through an irregular optical path, and the S / N ratio can be improved.

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

The light transmitting member 30 of the present embodiment has a bottom wall 3
The central portion of the outer surface of 1 protrudes toward the flooded surface F, and the tip curved surface of the protruding portion is formed so as to form a part of the spheroid as shown in FIGS. 8 and 9.
The curved tip forms the detection surface 35, and the contact point between the curved curved surface and the surface F to be immersed forms the positioning part 36. Around the detection surface 35, a guide portion 37 is formed which is continuous with the detection surface 35 and is inclined so that a gap S between the detection surface 35 and the immersion surface 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 denote a pair of focal points (FIG. 8) of the spheroid.
(See P1 and P2).

FIG. 8 is a cross-sectional view of the translucent member 30 along the direction in which the two optical fibers 12 and 13 are arranged in parallel. In FIG. 8, the shape of the detection surface 35 is clarified. For this reason, the fixing resin 14 and the like described in the first embodiment are omitted, and only the outer edge of the light transmitting member 30 is shown.

According to the present embodiment, when there is no liquid leakage L, the light emitted from the light projecting section 50 (the end surface 12A of the light projecting optical fiber 12) on one focal side of the spheroid is And the light is condensed on the other light receiving portion 51 (the distal end surface 13A of the light receiving optical fiber 13) on the other focal side. On the other hand, when a slight leak contacts the outer edge of the guide 37, the leak L moves smoothly to the detection surface 35 side along the guide 37. When the detection surface 35 comes into contact with the liquid leakage L, most of the light from the light projecting unit 50 passes through the detection surface 35 and passes through the light receiving unit 51.
Will not be collected. Thereby, the difference in the amount of received light in the light receiving unit 51 is more clearly distinguished depending on the presence or absence of the liquid 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 has a disk shape, and has a cylindrical body 49 (fixed in the first embodiment). (Corresponding to the resin 14 for use). On the lower surface of the light transmitting member 40, a ridge 40B is formed by projecting an outer edge thereof toward the surface F to be flooded, and a notch 48 is formed so as to cross one location of the ridge 40B.

As shown in FIG. 11, the ridge 40B is
The outer surface is formed so as to form a part of a cylindrical outer peripheral surface (a so-called cylindrical surface). And the ridge 4
0B constitutes a positioning portion 46, and the submerged surface F
Is hit. Further, both sides of the positioning portion 26 form a detection surface 45, and face the water immersion surface F via a gap S. Further, both the optical fibers for projecting and receiving light (only the optical fiber for receiving light 13 is shown in FIG. 11) are arranged such that the distal end surfaces thereof are on the axial center of the outer peripheral surface of the above-mentioned cylinder, and the middle part penetrates through the cylindrical body 49. It is fixed. The irradiated portion of the light from the light emitting optical fiber is disposed, for example, at a position 180 degrees away from the notch 48 on the detection surface 45.

In this embodiment, as is apparent from the above structure, similar to the first and second embodiments,
The detection surface 45 of the light transmitting member 40 also functions as the “guide unit” according to the present invention.

In the liquid leak sensor of the present embodiment, when the liquid leak L spreads along the detection surface 45 so as to be soaked, it cannot move beyond the notch 48 provided on the detection surface 45. It penetrates more widely on the side away from notch 48. Thus, no matter where the liquid L leaks on the detection surface 45, the liquid L reaches the position 180 degrees away from the notch 48 on the detection surface 45 quickly and reliably. And since the irradiated part of the light from the optical fiber for light projection is arrange | positioned in this position, early detection of the liquid leak L is attained.
In addition, since the detection surface 45 is formed in an annular shape, it is possible to cope with a case where the liquid L enters the liquid sensor from any direction. Further, since the positioning portion 46 also has an annular shape, positioning stability is good. Besides, the notch 48
Thereby, the inside and outside communicate with the annular ridge 40B,
Even if the air is thermally expanded 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 changes can be made without departing from the scope of the invention.

(1) In the second and sixth embodiments, the detection surface is constituted by a part of the cylindrical surface. However, as shown in FIG. Constitute the detection surface 60, and the two focal points P1 and P2 of the ellipse
The configuration may be such that the end faces 12A and 13A of both optical fibers 12 and 13 are arranged on the optical fiber.

(2) In each of the above embodiments, the detection surface is inclined or curved with respect to the surface to be immersed.
As shown in FIG. 3, a detection surface 60 is provided in parallel with the surface to be immersed F, and guides 61, 61 are provided on both sides of the surface to be immersed. It is good also as a structure inclined so that it might be separated from.

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

(4) In each of the above embodiments, the positioning portion is also formed integrally with the translucent member. However, the positioning portion is also formed as a separate member from the translucent member and fixed to the translucent member. The configuration may be as follows. Specifically, as shown in FIG. 13, prism-shaped positioning portions 62, 62 are formed as members separate from the light transmitting member 63, and these positioning portions 62, 62 are fixed to both side portions of the light transmitting member 63. It may be configured.

(5) Further, the positioning portion does not necessarily have to be configured to be in contact with the surface to be immersed. For example,
As shown in FIG. 14, the positioning portion 65 is fixed to the wall portion 64 rising from the flooded surface F by, for example, a screw T, and a gap S is formed between the detection surface 68 of the light transmitting member 67 and the flooded surface F. It is good also as composition which carries out positioning so that it may face via.

[Brief description of the 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 liquid leakage sensor.

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

FIG. 4 is a cross-sectional view of the liquid leakage sensor taken along the line AA in FIG. 3;

FIG. 5 is a cross-sectional view of the liquid leakage sensor taken along the line BB of FIG. 3;

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

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

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

FIG. 9 is a cross-sectional view of the liquid leakage 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 liquid leakage sensor.

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

FIG. 13 is a cross-sectional view of a liquid leakage sensor according to a second modification.

FIG. 14 is a cross-sectional view of a liquid leakage sensor according to a third modification.

FIG. 15 is a sectional view of a conventional liquid leakage sensor.

FIG. 16 is a sectional view of a conventional liquid leakage sensor.

[Explanation of symbols]

 10, 20, 30, 40, 64: light-transmitting member 12: light-emitting optical fiber 13: light-receiving optical fiber 14: fixing resin 15, 25, 35, 45, 60, 62, 63: detection surface 16, 26, 36 , 46, 65 positioning part 22, 23 light shielding part 37, 61 guide part 50 light emitting part 51 light receiving part F ... flooded surface L ... liquid leakage S ... gap

Claims (7)

[Claims] 1. A light-transmitting member that is disposed opposite to a surface to be immersed in which liquid can be immersed in liquid leakage, and has a detection surface facing the surface to be immersed with a gap therebetween, and A light-emitting unit that emits light obliquely toward the detection surface from the opposite side of the water-immersed surface, and a light-receiving unit that receives reflected light emitted from the light-projection unit and reflected by the detection surface. A liquid leakage sensor that detects liquid leakage based on the amount of light received by the light receiving unit, wherein a gap between the surface to be immersed and the surface to be immersed is gradually directed toward a portion of the detection surface to which light from the light emitting unit is irradiated. A liquid leakage sensor characterized in that a guide portion for narrowing is provided. 2. The light-transmissive member is formed such that the detection surface is elongated in a plane parallel to the surface to be immersed, and the guide portion extends along a longitudinal direction of the detection surface. 2. The liquid leakage sensor according to claim 1, wherein the gap is formed so as to gradually narrow a gap between the detection surface and the surface to be immersed in the width direction of the detection surface. 3. The liquid leakage sensor according to claim 2, wherein the detection surface of the light transmitting member forms an annular shape in a plane parallel to the surface to be immersed. 4. The light-transmitting member according to claim 1, wherein the detection surface is formed in a shape that condenses the light emitted from the light-emitting unit to the light-receiving unit. A liquid leakage sensor according to any one of the above. 5. The light-transmitting member, wherein the detection surface is formed in a shape forming a part of a spheroid, and the light-projecting unit and the light-receiving unit are located at positions corresponding to a pair of focal points of the spheroid. The liquid leakage sensor according to claim 1, wherein 6. The light-emitting device according to claim 6, wherein the light-emitting unit comprises the other end of an optical fiber having one end facing the light-emitting element, and the light-receiving unit comprises the other end of an optical fiber having one end facing the light-receiving element. The liquid leakage sensor according to any one of claims 1 to 5, wherein: 7. A light-shielding portion is provided between the light-emitting portion and the light-receiving portion, the light-shielding portion being configured to restrict light from being directly supplied from the light-emitting portion to the light-receiving portion. Claim 1
7. The liquid leakage sensor according to any one of claims 6 to 6.