JP2001041844A - Liquid leakage sensor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a liquid leakage sensor which can be used safely even in an explosion-proof area where accidents tend to happen, can accurately detect the occurrence of liquid leakage regardless of the nature of the liquid leakage, and can precisely operate until the sensor outputs a detect signal. SOLUTION: A liquid leakage sensor is constituted in such a way that only the terminal sections 7 and 8 of light emitting and receiving devices are housed in a box-like or cylindrical sensor body 1 having a translucent bottom plate 3 made of transparent or translucent glass or synthetic resin and an opened top and the sensor body 1 is hermetically sealed with a lid 4 so that no liquid leakage may easily enter the sensor body 1 and, in addition, the risk of fire catching, etc., may not occur.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement in a liquid leakage detection device that detects whether or not a liquid leakage has occurred in a liquid leakage detection target area at an early stage.

[0002]

[Prior art] In factory facilities and other facilities,
Leakage can cause disaster or damage the facility itself, so it is necessary to know early on the occurrence of leakage. For this reason, various optical means have been proposed. However, for example, when light is irradiated to a filter made of thin paper or the like and liquid leaks into the thin paper, a change in the amount of light transmitted through the filter or reflected light can be detected, and the presence or absence of liquid leak can be known. In the case of liquids with high viscosity, it is difficult to penetrate thin paper, accurately detect changes in light amount, cannot detect liquid leakage, disadvantage that thin paper needs to be replaced at each reset, risk of danger When targeting high liquids, it is not suitable for practical use as a liquid leak sensor, such as a drawback that a handler encounters an unexpected disaster when replacing thin paper with little care. As a means for improving this defect, a transparent and translucent material is used to form a casing, and instead of the filter, a light transmitting plate is used as a component of the right casing so that a change in the amount of light can be accurately detected. Has been proposed. According to this configuration, it is possible to avoid the drawback of using thin paper for the filter, but since the conventional one contains the light emitting / receiving device and the electric circuit in the casing, the casing is eroded due to the property of liquid leakage. Alternatively, leakage of liquid into the casing due to damage to the casing sealing device due to physical force or other causes may damage the device, cause a failure of the leakage sensor, and furthermore, cause a danger of leakage. Was. In addition, when the temperature of the leaked liquid is high, it is unavoidable that the heat will cause a failure in the device inside the casing, and in any situation, the occurrence of the leaked liquid can be accurately notified (such as a buzzer). And)
It is not enough as a liquid leak sensor that should fulfill the function of preventing disasters and the like beforehand, and its improvement has been demanded. A particular problem is that in the case of a liquid leak sensor located in an explosion-proof area, flammable gas generated in the atmosphere can cause a major disaster due to sparks generated from electric circuits etc. for some reason. Sex must be completely dispelled. A leak sensor that takes this point into consideration has not yet been proposed.

[0003]

SUMMARY OF THE INVENTION It is an object of the present invention to improve a defect of the optical sensor, to eliminate a defect that causes a failure, and to provide a sensor that can detect liquid leakage safely and accurately. It is in.

[0004]

In order to solve the above problems, first, the structure of the sensor body is simplified as much as possible so as to withstand the erosion despite the nature of the liquid leakage. It needs to be hardened. Second
In addition, it is necessary to limit the devices housed in the sensor main body to those that are not likely to be damaged by the heat of the liquid leakage, and that there is no danger of ignition even if the devices are arranged in the explosion-proof area as described above. Third, even if a small amount of liquid leaks into the sensor main body, it is necessary to configure the sensor so that its function is not immediately impaired (it is necessary to accurately detect the occurrence of liquid leak). Therefore, if a liquid leak occurs unfortunately, the liquid leak sensor operates properly, and if this is notified, the liquid leak can be treated and then replaced with another sensor body.) Therefore, in the present invention, in order to address the first problem, the sensor body is
Only the terminal of the light emitting device and the light receiving device was housed in the sensor body while the bottom was formed in a box formed of a light transmitting plate. By doing so, the sensor body can be miniaturized (reducing the manufacturing cost and reducing the number of leak erosion targets), and since the simple structure is used, the number of hermetically sealed portions that are liable to leak erosion can be reduced to form a box. There is an advantage that even if the wall portion is made relatively thick, it does not become a factor that hinders the detection of liquid leakage as long as the portion where the light transmitting plate is formed is taken into consideration. In the second problem as well, only the terminal portions of the light emitting device and the light receiving device are housed, and the main body portion of the light emitting device and the light receiving device, the electric circuit, and the like are not housed. Regarding the third problem, it is very easy to protect the liquid from leaking only by the tip of the terminal portion of the light emitting device and the light receiving device, and the protection is performed while the leakage of the liquid is notified (alarm). Since it is not necessary to provide protection for a long time, even if liquid leaks into the sensor body, the tip of each terminal of the light emitting device and light receiving device will not be immediately immersed in the liquid. Protection is good.

[0005]

Embodiments will be described with reference to the drawings.
FIG. 1 is a partially cutaway explanatory view showing an outline of an embodiment of a liquid leakage sensor, and FIG. 2 is an explanatory view showing an embodiment of a light transmitting plate (3).
As described above, the present invention is an improvement of a known optical sensor, and when there is no liquid leakage, when light emitted from the light emitting device is reflected and reaches the light receiving device and liquid leakage occurs. Is configured so that the irradiation light becomes transmitted light and the amount of light reaching the light receiving device is reduced, and a change in the amount of light is detected to emit a detection signal, and transparent or translucent glass or synthetic resin is used. A light-transmitting plate (3) for reflecting irradiation light is provided at the bottom, and a box or a cylindrical sensor body (1) having an open upper end is formed. Terminal portions (7) and (8) of a light-emitting device and a light-receiving device are used. To accommodate. The sensor body (1)
A lid (4) is fitted separately from the wall (2) so that the liquid does not easily enter the inside from the opening. For example, a sealing member (5) is used, or a cap (6) is screwed. For example, it is preferable to prevent leakage of the liquid easily. In addition, when a large amount of liquid is expected when leakage occurs, the sensor body (1) may be formed to be vertically long. An optical fiber is used for the terminal portion (7) of the light emitting device and the terminal portion (8) of the light receiving device. With optical fiber, for example, thermal damage is limited to the optical fiber part and does not extend to other equipment parts, and recently commercially available optical fiber can withstand considerable heat, and in any case the sensor function Damage can be kept relatively small, and in particular, since it is possible to provide an electric circuit outside the explosion-proof area, such a disaster can be prevented.

[0006]

Embodiment 2 As described above, it is necessary for the liquid leak sensor to accurately detect when a liquid leak occurs, and to output the detection result as a signal. Therefore, the light radiated from the terminal portion (7) of the light emitting device toward the light transmitting plate (3) at the time of the liquid leakage occurs, and the liquid leaks and adheres to the outer surface of the light transmitting plate (3) to become transmitted light. The leak sensor detects the change in the amount of light due to the decrease in the reflected light from the light transmitting plate (3) reaching the terminal portion (8) of the device, and outputs a detection signal until the leak is detected until the leak is detected. It must work properly. In other words, it is necessary for the leak sensor to operate properly.
It is not required to continue for a long time after the occurrence of liquid leakage. Although the liquid does not easily penetrate into the sensor body (1) according to the present invention, when it unfortunately enters, the terminal part (7) of the light emitting device and the light receiving device immediately
Each tip of (8) is immersed in the liquid leakage, and the vicinity of the tip is protected by a protective member ( 9).

[0007]

Embodiment 3 When the light-transmitting plate (3) is provided in the form of a flat plate on the bottom of the sensor body (1), the light-transmitting plate (3) is arranged in a liquid-leakage detection target area in a state where there is no liquid leakage. When
The light amount reaching the light receiving device is not constant when there is no liquid leakage, affected by the brightness, color, etc. of the liquid leakage detection target area. This makes it impossible to accurately detect a change in the amount of light when a liquid leak occurs. Therefore, the outer surface of the light transmitting plate (3) is provided with a plurality of sawtooth-shaped irregularities having a cross-sectional shape of an isosceles triangle having an apex angle of 90 ° in a horizontally long and parallel manner, without being affected by the above. Desired reflected light can be obtained.

[0008]

The liquid leakage sensor according to the present invention can be used in an explosion-proof area where an accident is likely to occur, and can accurately detect the occurrence of liquid leakage regardless of the cause, and accurately detect a leakage signal. Can be expected to work. Further, even if damage occurs, the portion after the optical fiber can be replaced, so that it can be used very inexpensively in terms of cost.

[Brief description of the drawings]

FIG. 1 is a partially cutaway explanatory view showing an outline of an embodiment.

FIG. 2 is an explanatory view showing an embodiment of a light-transmitting plate (3).

[Explanation of symbols]

 1. Sensor body 2. Wall 3. Translucent plate 4. Lid 5. Seal member 6. Cap 7. Light emitting device terminal part 8. Light receiving device terminal part 9. Protection member

Claims (3)

[Claims] 1. A liquid leakage sensor comprising a light emitting device, a light receiving device, and a device for detecting a change in the amount of light reaching the light receiving device and issuing a detection signal, wherein a transparent or translucent glass or synthetic resin is used, and A light transmitting plate (3) for receiving and reflecting the irradiation light is provided, and a box or a cylindrical sensor main body (1) having an open upper end is formed, and the light transmitting plate is provided in the sensor main body (1). Terminal part (7) of light emitting device for irradiating light toward light plate (3) and light transmitting plate (3)
(4) for receiving a terminal portion (8) of a light receiving device for receiving light reflected from the light receiving device, and providing a lead-out opening for the terminal portion (7) of the light emitting device and the terminal portion (8) of the light receiving device. Liquid leak sensor, wherein a liquid is fitted into an opening of the sensor body (1). 2. A terminal (7) of the light emitting device and a portion of the terminal portion (8) of the light receiving device which do not hinder light irradiation and light reception near the respective tips are covered with a protective member (9). The liquid leakage sensor according to claim 1. 3. The light-transmitting plate (3) is provided with a plurality of sawtooth-shaped irregularities having a cross-sectional shape of an isosceles triangle having a vertex angle of 90 ° in a laterally and parallel manner. 3. The liquid leakage sensor according to claim 1, wherein: