JPS618625A - Liquid level sensor - Google Patents

Abstract

PURPOSE:To use titled sensor even the liquid having bigger viscosity by deforming the partitioned chamber composed of bellows, etc. according to the height of the liquid level of the inside of a tank and by providing a shielding plate body shielding a light when the liquid level is raised. CONSTITUTION:The cylinder part of a partition chamber 1 is made of a bellows, etc., 1a and telescopically, and a float 1b is provided at the lower part. An emission part 2, photodetecting part 3 and control part 4 are also provided on the upper part and a glass fiber 5 is extended from the emission part 2 and photodetecting part 3 and the tip part thereof is opposed. A shielding body 6 is provided under the opposing glass fiber thereof. When the partition chamber 1 is dipped into the liquid 10, then, the bellows 1a is contracted, the shielding body 6 enters between the tip part of the optical fiber 5 to shield the light, which does not reach the detecting part 3. Since the light shielding body is provided inside the partition chamber deforming according to the height of the liquid level the liquid level of even the liquid having bigger viscosity can be detected with high accuracy.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of the Invention] The present invention relates to a liquid level sensor that detects the amount of liquid in a tank.

[Prior art and its problems]

The lower end surface of the transparent body is formed by two planes that are orthogonal to each other, and the light emitting part emits light from the upper end surface toward one of the planes, and the light rays reflected from that plane are further reflected by the other plane to form the incident light beam. A sensor is used that generates an output at the light receiving part by the light beam that travels parallel to the surface of the liquid and reaches the upper end surface.The sensor is placed above the liquid surface, and the refractive index of the liquid's light is larger than that of air. Therefore, the reflectance of the incident light beam at the lower end surface decreases, and as a result, the amount of light reaching the light receiving section decreases.Therefore, there are devices that detect the liquid level by reducing the output.

In such devices, in the case of liquids such as gasoline, diesel oil, or water that have low viscosity and do not stick to transparent materials, when the liquid level falls again, the liquid does not adhere to the sensor surface, and as a result, the output of the light receiving section decreases. Once recovered, it is possible to detect a drop in the liquid level.

However, liquids that tend to stick to transparent materials with high viscosity such as heavy oil, lubricating oil, or starch syrup will not adhere to the bottom surface even if the liquid level once rises and reaches the bottom surface of the sensor falls again. As a result, the output of the light receiving section does not decrease, and there is a drawback that a drop in the liquid level cannot be detected.

In order to solve this drawback, the applicant first covered the lower end of a transparent body having mutually orthogonal lower end surfaces with an elastic bag in the axial direction, and filled the bottom with a liquid that does not easily stick to the transparent body. (Patent Application No. 118278/1983).

JP-A No. 58-19513), however, in a device that utilizes such a prismatic effect, the transparent body itself requires a certain size, and it also takes a certain amount of time to capture changes in light due to changes in reflectance. A certain movement is required,
There is a risk that it will not be able to respond to delicate liquid level transitions.

[Purpose of the invention]

The object of the present invention is to solve the disadvantages of the conventional example, to be able to be used for liquids with high viscosity, and to be able to be made small as a whole.
Another object of the present invention is to provide a liquid level sensor that can improve detection accuracy because it can act directly on the detection section.

[Key points of the invention]

However, according to the present invention, this purpose is achieved by providing a light emitting part and a light receiving part facing each other in a compartment that deforms due to the movement of the liquid level, and a means for controlling the transmission of light between the two by the movement of the compartment. achieved.

[Embodiments of the invention]

Embodiments of the present invention will be described in detail below with reference to the drawings.

Fig. 1 is a longitudinal sectional front view showing the usage state of the liquid level sensor of the present invention, Figs. 2 and 3 are longitudinal sectional front views showing the first embodiment of the liquid level sensor of the invention, and 1 in the figure is halfway A bellows part 1a that expands and contracts is provided, and the lower end is a closed chamber to form a float 1b, which is a compartment that expands and contracts and deforms with the vertical movement of the liquid level. They were arranged side by side, and furthermore, a control device 4 to which these light emitting bodies 2 and light receiving bodies 3 were connected was attached to the upper part. In the figure, 1c indicates an air inlet/outlet hole.

In the compartment 1, optical fibers 5 and 51 are protruded from the light emitter 2 and the light receiver 3, respectively, and a light emitting part 5a and a light receiving part 5a1 formed at the tips thereof are opposed to each other with an appropriate small distance between them. .

On the other hand, a light shielding body 6 made of, for example, a small projection was protruded from the upper end of the float 1b so as to move with the movement of the compartment 1.

This light shielding body 6 can be interposed between the light emitting section 5a and the light receiving section 5a", and serves to control the transmission of light between the two.

Then, a sensor having the above structure was installed above the liquid tank 7, and the output of the photoreceptor 3 was introduced into the electromagnetic valve 9 in the middle of the liquid injection pipe 8 via the control device 4.

Next, to explain the operation and effect, from the liquid injection pipe 8 to the liquid tank 7.
If the liquid level of the liquid 10 injected into the interior does not reach the compartment 1 as shown in FIG. 1, the compartment 1 extends as shown in FIG. and light receiving section 5 a +
Since the light emitted from the light emitting body 2 reaches the light receiving body 3 via the light emitting part 5a and the light receiving part 5aJ, the control device 4 does not produce an output due to the output of the light receiving body 3.
The solenoid valve 9 is open and liquid injection continues.

When the liquid level of the liquid 10 rises and reaches the float 1b, the compartment 1 deforms and contracts due to the buoyancy of the float 1b, as shown in FIG. As a result, the output of the photoreceptor 3 decreases, so that the control device 4
An output is generated, the solenoid valve 9 closes, and the liquid injection stops.

When the liquid level of the liquid 10 falls, the compartment 1 deforms and stretches, and the light shielding body 6 separates from between the light emitting part 5a and the light receiving part 5a1, and as a result, the electromagnetic valve 9 opens and the liquid is poured again.

FIG. 4 is a longitudinal sectional front view showing a second embodiment of the liquid level sensor of the present invention, in which electric wires are connected to the control device 4 instead of the light emitter 2, light receiver 3, and optical fibers 5, 5' of the first embodiment. The light emitting body 12 and the light receiving body 13 were provided directly facing each other in the compartment 1 with an angle of 11, 11 degrees interposed therebetween, and the light shielding body 6 was positioned so as to be able to intervene between the light emitter 12 and the light receiving body 13. The luminous body 1
2. For the photoreceptor 13, it is conceivable to use a combination of a light emitting diode, a fat transistor, or the like.

In this way, the overall length can be made even smaller, but
The operation and effects are similar to those in the first embodiment, so detailed explanation will be omitted.

Furthermore, as a third embodiment, as shown in FIG.
Instead, a light shielding body 14 having a transparent portion 14a formed of a hole may be provided. In operation in this third embodiment, the light shield 14 blocks transmission of light when the liquid level is low and the compartment 1 is extended, and transmits light when the liquid level rises and the compartment 1 contracts. Light is transmitted via the light section 14a. Therefore, the output of the control device 4 may be reversed from that of the first and second embodiments.

Furthermore, as a fourth embodiment, as shown in FIG. 6, a liquid 15 with a low viscosity such as gasoline, light oil, or water may be used instead of the light shield 6.14, and this may be used as a kind of light shield. good. The presence of the liquid 15 between the light emitting body 12 and the light receiving body 13 changes the amount of light transmitted, and this change is detected by the control device.

〔Effect of the invention〕

As described above, the liquid level sensor of the present invention can be used for liquids with high viscosity, except for the disadvantage that conventional transparent sensors cannot detect liquids with high viscosity that adhere to the lower end surface. Moreover, since the light is directly controlled between the light-emitting part and the light-receiving part, even the slightest change can be detected, improving accuracy.Also, since the detection part can be made smaller, the overall size can be reduced. It is.

[Brief explanation of drawings]

FIG. 1 is a longitudinal sectional front view of the sensor of the present invention with 11 digits placed in a liquid tank, and FIGS.
An example is shown in which FIG. 2 is a longitudinal sectional front view with the sensor compartment extended, FIG. 3 is a longitudinal sectional front view with the sensor compartment contracted, and FIGS. 4, 5, and 6 are FIG. 7 is a longitudinal sectional front view showing a second embodiment, a third embodiment, and a fourth embodiment of the sensor of the present invention, respectively. 1... Compartment 1a... Bellows part 1b.
...Float 1c...Air inlet/outlet hole 2...Light emitter 3...Photoreceptor 4...Control device 5.5'...Optical fiber 5a...Light emitting section 5a''...Light receiving section 6... Light shielding body
7...Liquid tank 8...Liquid injection pipe 9...Solenoid valve 10-...Liquid 11.11'...Electric wire 12...Light emitter 13...Photoreceptor 14.
... Light shielding body 14a ... Transparent part] 5 ... Liquid with low viscosity Applicant Tokyo Tatsuno Co., Ltd. Figure 5 Figure 6

Claims (1)

[Claims] 1. A liquid level sensor, characterized in that, in a compartment that deforms due to movement of the liquid level, a light emitting part and a light receiving part facing each other and a means for controlling transmission of light between the two by the movement of the compartment are provided.