JP2001165805A - Liquid leakage sensor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a liquid leakage sensor which is safe even when it is used in an explosion-proof area where accidents are likely to occur, correctly detects generation of the liquid leakage irrespective of the nature of the leaked liquid, and is correctly operated until the detection signal is generated. SOLUTION: The liquid leakage sensor comprising a light emitting device, a light receiving device and a device to detect the change in light quantity of the light while it is irradiated by the light emitting device and reaches the light receiving device and to generate the detection signal, an end portion 4 of the light emitting device, a triangular prism 2 to achieve the refraction and irradiation of the irradiated light from the end portion 4 of the light emitting device onto a transmissive plate 3, and an end portion 5 of the light receiving device to receive the reflected light from the transmissive plate 3 via the triangular prism 2 are stored in a sensor body 1 to solve the problem.

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. For this reason, a light transmitting plate for receiving irradiation light and reflecting the light is formed on the bottom of the casing, and a terminal portion of a light emitting device for irradiating light toward the light transmitting plate is formed in the casing and the light transmitting plate. A liquid leakage sensor that accommodates only the terminal portion of the light receiving device for receiving light reflected from the light transmitting plate, that is, the remaining sensor component is provided outside the casing to avoid the danger has been proposed. (Japanese Patent Application No. 11-252080), in order to avoid the above-mentioned danger, there is a problem in forming the material of the terminal portion of the light emitting device and the terminal portion of the light receiving device using a material with less danger.

[0003]

SUMMARY OF THE INVENTION It is an object of the present invention to solve the above-mentioned problems and to propose a sensor capable of detecting a liquid leak safely and accurately.

[0004]

In order to solve the above-mentioned problems, first, it is possible to maintain the advantage that the configuration of the casing, that is, the configuration of the sensor main body can be simplified. It must be hardened to withstand the erosion. Second, the device to be housed in the sensor body is limited to a material that is not likely to be damaged by the heat of the leaked liquid. In this way, the danger of ignition can be avoided even in the explosion-proof area. Third, it is necessary to make it possible to configure such that even if a small amount of liquid leaks into the sensor main body, its function is not immediately impaired.
However, in the liquid leak sensor using optical means, since the light from the light emitting device detects the presence or absence of the liquid leak by a change in the amount of light reaching the light receiving device as reflected light, the invention described in When an optical fiber is used for each terminal of the device and the light receiving device, in order to appropriately set the angle of incidence on the light-transmitting plate provided at the bottom of the sensor main body, and thus also the angle of reflection, the optical fiber is set at a desired angle with respect to the incident surface. Must be set to an angle. However, if the optical fiber is made of a flexible and flexible material and structure, it can be appropriately bent in the sensor body and formed at a desired angle, but the material can be used even at high temperature (150 ° C. or higher). Fibers (for example, those made of quartz or synthetic quartz) have restrictions on use such as a minimum bending radius of 30 mm or more (the sensor body becomes large if configured to satisfy these restrictions). Further, for example, when the terminal portion of the light emitting device and the terminal portion of the light receiving device are housed in the sensor main body at a distance so that the incident angle and the reflection angle can be obtained without bending, simplification (miniaturization) ), Which is contrary to the demand for robustness. As the sensor body becomes larger, the place where it can be installed is limited, the speed of detecting the leak is reduced (for example, the distance from the leak to the light transmitting plate becomes longer), and the amount of the leak to be detected is reduced. When the amount is small, detection cannot be performed, and the functions of preventing a disaster from occurring are reduced, and disadvantages such as increasing the manufacturing cost of the liquid leakage sensor are caused. Therefore, in the present invention, using a triangular prism, even if the respective terminal portions of the light emitting device and the light receiving device are accommodated in the sensor main body so as to be parallel to each other, the triangular prism is formed with a desired refractive index according to Snell's law. The incident light refracted on the bottom surface is configured to reach the terminal portion of the light receiving device (when the bottom surface of the triangular prism is used as a detection surface), or the incident light transmitted through the triangular prism is formed on the bottom of the sensor main body. The light was reflected by the plate and passed through the triangular prism to reach the terminal portion of the light receiving device.

[0005]

Embodiments will be described with reference to the drawings.
FIG. 1 is an explanatory view showing an outline of an embodiment of a liquid leakage sensor, and FIG.
Is an explanatory view showing an embodiment in which a light transmitting plate (3) is provided at the bottom of the sensor body (1), and FIG. 3 is an explanatory view showing an embodiment in which the bottom surface of the triangular prism (2) is used as a detection surface. It is.
As described above, the present invention is an improvement of the optical sensor, when there is no liquid leakage, the light emitted from the light emitting device is reflected and reaches the light receiving device, and when liquid leakage occurs, The present invention relates to an improvement of a liquid leakage sensor configured so that irradiation light becomes transmitted light and the amount of light reaching a light receiving device is reduced, and a change in the amount of light is detected to generate a detection signal. The terminal portion of the light emitting device and the terminal portion of the light receiving device are housed in the sensor body (1) using, for example, an optical fiber made of quartz or synthetic quartz so as to withstand high temperatures, and are illuminated by the triangular prism (2). Due to the refraction of light, the light is transmitted to the light transmitting plate (3), which is the liquid leakage detection surface (FIGS. 1 and 2), or the bottom surface of the triangular prism (2) is configured as the liquid leakage detection surface (FIG. 3).
However, the refractive index of the triangular prism (2) is selected and used according to Snell's law. in this case,
For example, when a large amount of liquid is expected to occur when a liquid leak occurs, the sensor body (1) may be formed to be vertically long. Therefore, the selection of the refractive index is taken into consideration according to the expected situation of the detection target. There must be. Also, whether or not to provide the light-transmitting plate (3) should be selected in consideration of the influence of light and darkness, color, and the like of the liquid leakage detection target area. That is, when the detection surface of the liquid leakage is affected by the brightness and color of the sensor installation area and there is a possibility that the amount of light reaching the light receiving device may not be constant when there is no liquid leakage, for example, a light transmitting plate (3) is provided. This is because it is necessary to consider that the cross-sectional shape is set to a saw-tooth shape having a vertex angle of 90 ° to avoid the influence.

[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 an explanatory diagram showing an outline of an embodiment.

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

FIG. 3 is an explanatory view of an embodiment in which the bottom surface of the triangular prism (2) is used as a detection surface.

[Explanation of symbols]

 1. Sensor body 2. Triangular prism 3. Translucent plate 4. Terminal part of light emitting device 5. Terminal part of light receiving device

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 bottom portion is provided. A terminal portion (4) of a light emitting device on a sensor body (1) provided with a light-transmitting plate (3) for receiving and reflecting irradiation light or a cylindrical sensor body;
A triangular prism (2) for refracting and irradiating the light emitted from the terminal portion (4) of the light emitting device to the light transmitting plate (3);
A liquid leakage sensor containing a terminal portion (5) of a light receiving device for receiving reflected light from the light transmitting plate (3) through the triangular prism (2). 2. 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. The liquid leakage sensor according to claim 1, wherein 3. 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, using a transparent or translucent glass or synthetic resin, A terminal part (4) of a light emitting device for fixing a triangular prism (2) to the bottom of a cylindrical sensor body (1) and irradiating light to the triangular prism (2); A liquid leak sensor characterized in that a terminal part (5) of a light receiving device for receiving irradiation light emitted from a terminal part (4) of the above through the triangular prism (2) is accommodated in the sensor body (1).