JPS5827456Y2 - Liquid level detection device using optical fiber - Google Patents

Description

[Detailed description of the invention] This invention uses optical fibers to safely and accurately detect the level of not only water and sludge, but also highly flammable and explosive liquids such as gasoline and alcohol. This invention relates to a level detection device.

Conventionally, a friction level switch has been mainly used as a level detector for detecting the level of liquid such as water or sludge.

This fricto level switch has a float installed in a water tank in which a liquid is stored, and a switch inside the float is connected to an external power source via an underwater cable, and is turned on or off in response to changes in the level of the liquid. The idea is to detect the liquid level by extracting electrical signals from the liquid.

However, in a level detector based on such a frict level switch, if damage occurs to the float or the underwater cable that is a path for electrical signals, there is a risk of electrical leakage, which is extremely dangerous for humans and livestock.

Therefore, it could not be used to detect the level of flammable or explosive liquids such as gasoline.

Furthermore, if an attempt is made to use a low voltage in order to reduce such leakage current, there are drawbacks such as difficulty in long-distance transmission and increased susceptibility to external noise.

This invention was developed in view of the above circumstances, and by making it possible to detect the level of liquid using light, it is possible to detect not only water and sludge, but also highly flammable and explosive substances such as gasoline and alcohol. It is an object of the present invention to provide a liquid level detection device using optical fibers that can safely and accurately detect liquid levels.

An embodiment of the present invention will be described below with reference to the drawings.

Figure 1 shows the configuration of a liquid level detection device using optical fibers. 1 is a float with almost the same shape as a light bulb, and the inner wall of the spherical part has a non-reflective film 2 to eliminate light reflection. It is coated.

Further, a rotary arm 3 is attached to an end portion of the float 1 which is tapered by forming a tapered surface from the spherical portion.

Into such a float 1, an optical fiber 4 consisting of two lines for transmitting and receiving light is introduced from an opening on the tapered end side.
The destination port and light receiving port are directed toward the non-reflection film 2 on the bottom of the spherical surface.

In addition, a reflecting plate 5 is provided near the light transmitting port and the light receiving port of the optical fiber 4 inside the float 1, and this reflecting plate 5 is always rotated in the vertical direction by its own weight on a rotating shaft 2a attached to an appropriate location inside the float 1. Let's play together so that we can face each other.

Such a float 1 is provided at a predetermined location inside a container (not shown),
The rotating arm 3 is rotatably attached to a mounting bracket 6 attached to the inner wall surface of the container.

As shown in FIG. 2 in detail, this mounting bracket 6 is provided with arm stoppers 7 and 7' diagonally above and below the support shaft of the rotary arm 3, depending on the level of the liquid. This restricts the range of rotation of the float 1 in one direction, that is, the range from the vertical state to the horizontal state.

On the other hand, 8 is a charge conversion level detector placed far from the container, and this level detector 8 includes a light emitter 9, a light receiver 10, and a contact 11 that responds to the output of this light receiver 10 exceeding a certain level. It is something that

Further, the light emitting line of the optical fiber 4 described above is connected to the light emitter 9, and the light receiving line is further connected to the light receiver 10.

Next, the operation of the liquid level detection device using the optical fiber having such a configuration will be explained.

Level 1, where the liquid in the container is located below float 1
2, the float 1 is held almost vertically by the arm stopper 7' of the mounting bracket 6, and is in the state shown by the solid line in the figure.

In this state, when the light emitter 9 of the charge conversion level detector 8 is operated to emit light, this light 13 is guided into the float 1 and inside through the light transmission line of the optical fiber 4, and is transmitted from its light emitting port to the spherical bottom surface. irradiated towards the area.

However, in this case, since the spherical part of the float 1 is coated with a non-reflective film, the light 13 is not reflected.

Therefore, since the light receiver 10 does not sense the reflected light, no output is sent out, and therefore the contact 11 does not close.

FIG. 3 shows such a state.

'Next, when the level of the liquid gradually rises and reaches the position 14 in the figure, the float 1 rotates in the direction of the arrow shown as the level of the liquid rises and floats up to the state shown by the dotted line in the figure.

At this time, the reflecting plate 5 is loosely aligned with respect to the rotating shaft 2a, so that it is always maintained in the vertical direction, with its reflecting surface facing the light emitting port and the light receiving port of the optical fiber 4.

Therefore, in such a state, when light is transmitted from the light emitter 9 of the photoelectric conversion level detector 8, this light is guided into the float 1 through the light transmission line of the optical fiber 4, as described above.
Light is emitted from the light emitting port toward the reflecting plate 5.

The light 13 irradiated on this reflection plate 5 is reflected, and the reflected light is transmitted to the photoelectric conversion level detector side and is sent to the light receiver 1.
It senses at 0, converts it into an electrical signal, and sends out an output.

Therefore, the contact 11 is closed by this output, and it is possible to detect that the liquid level has reached a predetermined level.

FIG. 4 shows such a state.

In this way, even if optical fibers are used to detect the liquid level by light, and the charge conversion level detector is installed far from the container in which the liquid is stored, water, sludge, etc. In addition, it is possible to safely detect the level of highly flammable and explosive liquids such as gasoline, alcohol, and thinner, without any risk of electrical leakage or heat generation due to damage to the connection cable to an external power source, unlike conventional methods. can.

Furthermore, since it is not affected by external noise, it is possible to accurately detect the liquid level.

Note that the present invention is not limited to the embodiments described above.

For example, the mounting of the arm stoppers 7 and 7' in Fig. 2 may be changed and provided at approximately symmetrical positions with respect to the rotating arm 3, so that the float 1 floats to the left in the figure. It can be implemented in

As explained above, according to the present invention, the level of liquid can be detected by light using optical fibers, so it is possible to detect not only water and sludge but also highly flammable and explosive substances such as gasoline and alcohol. A liquid level detection device using optical fibers that can safely and accurately detect the level of liquid can be provided.

[Brief explanation of drawings]

Fig. 1 is a configuration showing an embodiment of the liquid level detection device using optical fibers of the present invention, Fig. 2 is a perspective view showing details of the arm stopper in Fig. 1, and Figs. 3 and 4 are the same. In an example, it is a principle diagram at the time of non-operation and operation accompanying a liquid level change. 1...Float, 2...Non-reflective film, 3...
...Rotating arm, 4...Optical fiber, 5...
...Reflector, 6...Mounting bracket, 7゜7'・
... Arm stopper, 8 ... Photoelectric conversion detector, 9 ... Light emitter, 10 ... Light receiver, 11 ... Contact.

Claims (1)

[Scope of utility model registration request] A float is provided in a container containing a liquid so that it floats and rotates as the level of the liquid changes, and the inner wall surface of the space is coated with an anti-reflection film. a stopper that restricts the rotation of the float; an optical fiber cut from the light transmitting and light receiving lines introduced into the inside of the float so that the light transmitting and light receiving ports thereof face the non-reflective film; The optical fiber is provided with a reflector that is oriented vertically due to its own weight and that when the float reaches a predetermined liquid level, the sending/receiving port of the optical fiber faces a reflective surface, a light emitter, and a light receiver. A liquid level detection device using an optical fiber, characterized in that it is equipped with a charge conversion level detector that transmits and receives light through a light transmission line and a light reception line, and converts the received light into an electrical signal.