JPS61201118A - Optical liquid level gage - Google Patents

Abstract

PURPOSE:To measure the liquid level of liquid media to be measured based upon the light quantity of the reflecting light by providing the inclined-face at the optical sensor which reflects totally the incident light when contacting with gaseous media and transmits the incident light when contacting with the media to be measured. CONSTITUTION:When a light source 7 lights up, the rays of light pass through a convex lens 8, go to be a parallel beam, make incident on the light incoming part 2 of an optical sensor 1 and reach inclined-faces 5a-5n of level difference parts 4a-4n. Here, for example, when inclined-faces 5a-5d as well contact with the air and inclined-faces 5e-5n contact with a liquid fuel 12, the beam which reaches the inclined-faces 5a-5d is totally reflected. On the other hand, the beam which reaches the inclined-faces 5e-5n, transmits through the faces and is emitted to a fuel 12 side. The beam totally reflected by the inclined-faces 5a-5d, reaches inclined-faces 6a-6d, is totally reflected again, is emitted from a light coming-out part 3 and is irradiated to a photodetecting body 9. The light quantity of the reflecting light is the quantity corresponding to the liquid level of the fuel 12, the liquid level of the fuel 12 to the sensor 1 is detected based upon the resistance value measured by a resistance meter 10 and the level is converted to the depth from the bottom surface of a tank 13 to display 11 said value.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an optical level gauge suitable for use in measuring the level of liquid fuel in vehicles, combustion equipment, and the like.

[Conventional technology]

Conventionally, a float type liquid level needle has generally been used as this type of liquid level needle. This float type liquid level needle has a float at the tip of a rotatable arm.
The buoyancy of this float is used to measure the level of liquid fuel in a vehicle or the like. That is, the circuit resistance section is slidably changed in accordance with the rotation of the arm due to the buoyancy of the float, and the liquid level of the liquid fuel is measured from the change in the circuit resistance.

[Problem that the invention seeks to solve]

However, with such conventional liquid level needles, the circuit resistance section is slid by mechanical movement of an arm having a float, so the sliding section wears out and has an extremely short lifespan. there were. Furthermore, since it is composed of many types of mechanical parts, its reliability is poor, and assembly and manufacturing are difficult and require an excessive number of man-hours.

Furthermore, since the shape of the float is limited by the arm that supports the float, for example, when used in a fuel tank mounted on a vehicle, it is recommended to measure the liquid level at the center of the tank, where the amount of rocking is least. was difficult.

That is, the fuel in the tank fluctuates depending on the driving condition of the vehicle. Generally, this amount of rocking is large at the ends of the tank and becomes smaller toward the center of the tank. However, it is desirable to measure the liquid level at the center of the tank, but as mentioned above, the shape of the float-type liquid level needle is limited by its arm, etc. You will end up measuring the surface. Therefore, depending on the driving condition of the vehicle, the measured value may include a considerable error, resulting in a problem that the liquid level cannot be measured with high accuracy. Also,
Even if the shape of the arm etc. is skillfully designed so that the liquid level in the center of the tank can be measured, if the liquid level of the liquid fuel becomes low, the thickness of the float will interfere and the liquid level will be too low. This caused a problem in that it was not possible to measure.

[Means for solving problems]

The present invention has been made to solve these problems, and is designed to provide an optical sensor made of a transmissive light material that uses parallel light as incident light. An inclined surface is provided that transmits the incident light when it comes into contact with a liquid medium.

[Effect]

Therefore, according to the optical level meter according to the present invention, it is possible to measure the liquid level of the liquid medium to be measured relative to the optical sensor based on the amount of reflected light that is totally reflected on the inclined surface of the optical sensor.

[Foundation example]

Hereinafter, the optical liquid level meter according to the present invention will be explained in detail. 1st
The figure is a front view showing an embodiment of the optical sensor used in this optical liquid level gauge, and FIG. 2 is a sectional view taken along the line ■--■ in FIG. 1. This optical sensor 1 is formed from a thin plate made of a transparent light-transmitting material such as a colorless and transparent acrylic resin or glass, and has an entrance part 2 and a light output part having mirror-finished upper surfaces 2 and 3a at the upper end thereof. 3 is formed protrudingly. Further, on the front surface of this optical sensor 1, there are a plurality of step portions 4a to 4 with a predetermined width H (8vm>+predetermined step thickness t (0,4m)).
n is formed in a step-like manner, and a predetermined inclination angle α (45°±3 in this embodiment) is formed at both ends of each stepped portion 41 to 4n.
5n and 6a to 6n are formed, respectively. Inclination II of these inclined surfaces 5a to 5n, 6a to 6n
Hl is the light entrance part 2. Idemitsu 3 joins the party and Idemitsu width Hz (a
tI), and the inclined surfaces 51 to 5n,
The lower surfaces of 6a to 6n are mirror finished.

By the way, when measuring the liquid level, the light entrance part 2 of this optical sensor 1 has a
As will be described later, parallel rays are now incident,
This incident parallel ray is transmitted to the inclined surface 5 of the stepped portion 4&~4n.
a to 5n and in contact with the sloped surfaces 51 to 5n in the air region, the sloped surface 5a adjacent to the air region
The button is designed to cause total reflection at 5n, and the inclined surface 5a to 5
If the medium in contact with n is a liquid medium to be measured, the inclined surface 5
It is designed to transmit without being reflected at wavelengths a to 5n. That is, when the refractive index of the air is nt + the refractive index of the measuring liquid is nz (nz>n+), and the refractive index of the material of the optical sensor 1 is n3, the angle at which the incident parallel ray starts to cause total reflection ( Critical angle) θ is: When the adjoining medium is air, θl= sln
−”□ When the contacting medium is the liquid to be measured, θ2=s
in-1-. Therefore, the inclination angle α of the inclined surfaces 5IL to 5n is larger than 01, and smaller than θ2 (θ1<α
2) Then, the incident parallel light beam will be totally reflected in the air region and will be transmitted in the liquid region to be measured. That is, the inclination angle α=45°±3° in this embodiment is an inclination angle that satisfies the above-mentioned θ1<α−θ2 when the liquid to be measured is gasoline.

When the optical sensor 1 thus constructed is used to measure the level of liquid fuel, it is arranged as shown in FIG. 3 and used. That is, in the figure, 7 is a light source disposed at the focal point of a convex lens 8, and the convex lens 8 is a light input part 2 of the optical sensor 1.
They are disposed opposite to each other with a predetermined gap on the upper surface 2a of the. Further, a photoreceptor 9 such as a photoconductive element whose resistance value changes depending on the amount of light received is placed on the upper surface 3a of the light emitting part 3 of the optical sensor 1. It is connected to a resistance meter 10 that measures the resistance value of. The resistance meter 10 is connected to a digital display meter 11, and the liquid level of the liquid fuel 12 relative to the optical sensor 1 is detected based on the resistance value measured by the resistance meter 10. This is converted into and displayed on the display section of the display meter 11.

Note that 13 is a fuel tank serving as a container for the liquid fuel 12, and the optical sensor 1 has its lower side connected to the liquid fuel 12 of the tank 13.
It is arranged and fixed as if it were immersed in water.

Next, the operation of the optical liquid level gauge configured as described above will be explained. That is, in FIG. 3, when the light source 7 is turned on, the light emitted from the light source 7 passes through the convex lens 8, becomes a parallel light beam, and enters the light entrance section 2 of the optical sensor 1. This incident flat ray is transmitted to the inclined surfaces 5a to 5n of the stepped portions 4& to 4n.
reach. Here, for example, assuming that the slopes 5a to 5d are in contact with the air and the remaining slopes 56 to 5n are in contact with the liquid fuel 12, the parallel rays that have reached the steep slopes 5 to 5d are Total reflection occurs on the inclined surfaces 51 to 5d. However, the parallel light beams that have reached the inclined surfaces 5e to 5n are not totally reflected, but are transmitted through the inclined surfaces 5e to 5n and exit to the liquid fuel 12 side. The parallel light beams that are totally reflected on the inclined surfaces 5a to 5d reach the inclined surfaces 61 to 6d, where they are totally reflected again and try to be emitted from the light emitting section 3 as reflected light.

However, a photoreceptor 9 is placed on the exit portion 3, and the reflected light is irradiated onto the photoreceptor 9. Then, the resistance value of the photoreceptor 9 changes depending on the amount of reflected light. At this time, the amount of reflected light corresponds to the level of the liquid fuel 12 relative to the optical sensor 1. The resistance value of the pick and the photoreceptor 9 corresponds to the level of the liquid fuel 12, and this resistance value is measured by a resistance meter 10. Then, based on this resistance value, the liquid level of the liquid fuel 12 with respect to the optical sensor 1 is detected, converted to the depth of the liquid fuel 12 from the bottom of the tank 13, and displayed on the display section of the display meter 11. .

In FIG. 3, as the capacity of the liquid fuel 12 increases, the amount of reflected light irradiating the photoreceptor 9 decreases, and as the capacity decreases, the amount of reflected light increases. can measure the depth of liquid fuel. Also,
In FIG. 83, if the optical sensor 1 is placed so as to come into contact with the bottom surface of the tank 13, low liquid level measurement becomes possible.

In this embodiment, the liquid level of liquid fuel is measured, but it goes without saying that the present invention is not limited to measuring the level of liquid fuel, and may be used to measure the level of water, for example. Furthermore, it is not always necessary to display the liquid level, and other devices may be controlled based on a signal corresponding to the liquid level detected by the photoreceptor 9.

〔Effect of the invention〕

As explained above, according to the optical liquid level meter according to the present invention,
For optical sensors such as transparent materials that use parallel light as incident light,
Since we provided an inclined surface that totally reflects the incident light when it comes into contact with a gaseous medium and transmits the incident light when it comes into contact with a liquid medium to be measured, the amount of reflected light that is totally reflected by the inclined surface is used to determine the amount of light to be measured. The liquid level of the liquid medium can be measured using an optical sensor, and the structure is simpler than the conventional float-type liquid level needle, making assembly and manufacturing easier, and improving reliability and accuracy. It has many excellent effects.

[Brief explanation of the drawing]

Fig. 1 is a front view showing an embodiment of the optical sensor used in the optical liquid level meter according to the present invention, Fig. 2 is a sectional view taken along the If-II line in Fig. FIG. 2 is a schematic configuration diagram showing a state in which the meter is attached to a fuel tank. 1... Optical sensor, 2... Light entrance part, 3... Light output part, 4&~4n... Step part, 5&~5n, 6a~
6n... Slanted surface, 9... Photoreceptor.

Claims (1)

[Claims] It is characterized by being equipped with an optical sensor made of a transparent light material having a parallel light beam as incident light and having an inclined surface that totally reflects the incident light when it comes into contact with a gaseous medium and transmits the incident light when it comes into contact with a liquid medium to be measured. Optical liquid level gauge.