JP2515965B2 - Liquid level detection sensor - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid level detecting sensor capable of detecting a liquid level displacement by opening and closing an optical switch having a sensor lens composed of a light emitting element, a light receiving element and an optical prism. .

[0002]

2. Description of the Related Art Conventionally, as an example of a liquid level detecting sensor, there has been one as shown in FIG.

This shows the detecting portion of the sensor, in which a sensor lens 53 is provided at one axial end 52 of the element casing 51, and the sensor lens 53 is composed of an optical prism and is orthogonal to each other. It has first and second reflecting surfaces 54, 55.

A light emitting element 61 and a light receiving element 62 are provided in the element casing 51 so as to face the first and second reflecting surfaces 54 and 55, respectively, and the light emitting element 61 and the light emitting element 61 are provided via the sensor lens 53. An optical signal path 71 is formed between the light receiving element 62 and the light receiving element 62. The light emitting element 61, the light receiving element 62, and the sensor lens 53 form an optical switch Z.

When the optical switch Z of the liquid level detecting sensor X is in the air, the light from the light emitting element 61 is emitted from the light emitting element 61.
61 → first reflection surface 54 → second reflection surface 55 → an optical signal path 71 connecting to the light receiving element 62 is formed, and the optical switch Z is closed and in the ON state.

On the other hand, when the sensor lens 53 of the optical switch Z touches the liquid surface, the light from the light emitting element 61 is refracted by the first reflecting surface 54 and travels into the liquid, and is not transmitted to the light receiving element 62. Therefore, the optical switch Z is opened and turned off to generate a liquid level detection signal.

The axial direction of the liquid level detecting sensor X is perpendicular to the liquid surface, and the sensor lens 53 constituting the optical switch Z is arranged so that its reflecting surfaces 54, 54 face downward. ing. In FIG. 11, 81 is a sending optical fiber, 82 is a receiving fiber, 83 is a light emitting section, and 84 is a light receiving section.

However, in the liquid level detecting sensor X having such a structure, the sensor lens 53 forming the optical switch Z is located at the lowermost portion of the element casing 51 as described above, and therefore the first and the first switches Z of the switch Z are arranged. 2 If there were drops on the reflective surfaces 54 and 55, there was a risk of malfunction.

Therefore, a liquid level detecting sensor Y as shown in FIGS. 8 to 10 has been considered.

This is such that the optical signal path 8 is formed along a plane orthogonal to the axial direction of the element casing 1, and the sensor lens 3 is arranged so as to be along the axial direction of the element casing 1. The light emitting element 11 and the light receiving element 12 are arranged in parallel at a position facing the sensor lens 3 while being provided on one side wall 2.

That is, the element casing 1 formed in the upper opening is incorporated in the cylindrical sensor casing 20 shown in FIG. 9 (see FIG. 8).

The sensor casing 20 is provided to prevent the entry of light, but has an air hole 29 so that the liquid level can be accurately detected.

Further, as shown in FIG. 8, an element housing space 5 is formed therein, and a light emitting element 11 and a light receiving element 12 are arranged side by side in the space 5 (FIG. 10). 10 is a light emitting element
This is an element assembly in which 11 and the light receiving element 12 are molded in parallel and can be integrally housed in the element housing space 5.

Further, in FIG. 8, 4 is an element storage space 5
The sensor packing 6 fitted to make the airtight state is an external lead wire penetrating the sensor packing 4, and is connected to the three lead wires 7 extending from the element assembly 10.

The element casing 1 is made of a transparent hard synthetic resin, and a sensor lens 3 is integrally formed on one side wall 2 along the axial direction of the element casing 1.

Similar to the conventional example shown in FIG. 11, the sensor lens 3 is composed of an optical prism, and its upper end is located slightly above the element casing 1, and
The lower end is formed so as to project from the element casing 1.

Further, as shown in FIG. 10, it has first and second reflecting surfaces 3a and 4a orthogonal to each other, and both reflecting surfaces 3a and 4a.
The intersecting ridgeline 9 of a is parallel to the axis of the element casing 1.

Then, the light emitting element 11 and the light receiving element 12
Is disposed in the element housing space 5 so as to face the first and second reflecting surfaces 3a and 4a, respectively, and through the sensor lens 3,
An optical signal path 8 is formed between the light emitting element 11 and the light receiving element 12.

The light emitting element 11, the sensor lens 3, and the light receiving element 12 described above constitute an optical switch S. When the optical switch S of the liquid level detecting sensor Y is in the air, the light emitting element
Light from the light emitting element 11 → the first reflecting surface 3a → the second reflecting surface
4a → The light receiving element 12 is connected to form the optical signal path 8, and the optical switch S is closed and turned on.

On the other hand, when the sensor lens 3 of the optical switch S touches the liquid surface, the light from the light emitting element 11 travels into the liquid while being refracted by the first reflecting surface 3a and is not transmitted to the light receiving element 12. Therefore, the optical switch S is opened and turned off, and a liquid level detection signal is emitted.

The liquid level detecting sensor Y having the above structure has a drawback of the conventional liquid level detecting sensor X shown in FIG. 11, that is, a drop or the like is easily attached to the sensor lens 53 to cause a malfunction. Has been improved.

[0022]

However, the liquid level detection sensor Y having the above structure still has the following drawbacks.

That is, since the element casing 1 and the sensor lens 3 are made of transparent synthetic resin, the liquid level rises and the liquid level detection sensor Y detects the liquid level. At this time, if light enters from the outside, the outside light may pass through the air hole 29 of the transparent element casing 1 and the sensor lens 3 and enter the light receiving element 12.

Therefore, the optical switch S is kept in the ON state, which causes a malfunction that the liquid level to be detected cannot be detected.

In the conventional liquid level detecting sensors X and Y having the above-mentioned structure, the result of an experiment conducted by sampling a plurality of sensors shows that when visible light acts as a disturbance,
It is known that malfunction occurs when the illuminance is about 1,000 lx to 3,000 lx.

In general, when such liquid level detection sensors X and Y are used in an oil pump, etc., the illuminance by visible light in a tank containing kerosene is 400 lx or less indoors, but when used outdoors Due to the high illuminance of sunlight, the probability of malfunctions was extremely high, and there were many calls for improvement.

An object of the present invention is to provide a liquid level detecting sensor which can solve the above problems.

[0028]

According to the present invention, there is provided a sensor lens comprising an optical prism for refracting and reflecting light.
A light emitting element that emits light and a light receiving element that receives light from the light emitting element are arranged in parallel at a position facing the sensor lens,
In the liquid level detection sensor that forms an optical signal path between the light emitting element and the light receiving element via the sensor lens,
The above-mentioned sensor lens relates to a liquid level detection sensor, which is configured to allow infrared rays to pass therethrough while reducing the amount of visible light entering as much as possible.

The present invention is also characterized by the following configurations.

(A) The sensor lens is made of a colored transparent material such as smoked color.

(B) A colored or colored film was attached to the sensor lens.

(C) The sensor lens is provided along the axial direction in the sensor casing, and the light emitting element and the light receiving element are arranged in parallel at a position facing the sensor lens, and the sensor lens is interposed therebetween. An optical signal path for optically coupling the light emitting element and the light receiving element is formed on a plane orthogonal to the axial direction of the sensor casing.

(D) The sensor lens is integrally formed on one side wall of a cylindrical element casing that houses the light emitting element and the light receiving element, and infrared rays are transmitted through the entire element casing including the sensor lens. And the visible light was designed to reduce its penetration as much as possible.

(E) The sensor lens is integrally formed on one side wall of a cylindrical element casing for accommodating the light emitting element and the light receiving element, and only a portion for forming an optical signal path is colored in smoke or the like. The other parts were molded in two colors using a colored material that does not transmit light.

(F) The entire element casing including the sensor lens is formed of a smoke-colored synthetic resin that transmits infrared rays and reduces the penetration of visible rays as much as possible.

(G) The light emitting element and the light receiving element were arranged in an element assembly, and the light emitting element was coated with a transparent coating material while the light receiving element was coated with a black coating material.

[0037]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is an explanatory view of an oil supply pipe equipped with a liquid level detecting sensor according to the present invention, FIG. 2 is a perspective view of an element casing of the liquid level detecting sensor, and FIG. 3 is a vertical section of the element casing. It is a side view.

The structure of the liquid level detection sensor A according to the present invention is the same as that of the conventional example shown in FIGS. 8 to 10, and the same components will be described using the same reference numerals as those of the conventional example. .

In FIG. 1, P is an electric oil supply pump, and the liquid level detection sensor A according to the present invention is incorporated in the oil supply pump P.

The liquid level detecting sensor A is arranged in the sensor casing 20, and the sensor casing 20 is attached to the sensor pipe 22 attached to the tip of the bellows type oil supply hose 21 of the oil supply pump P.

Reference numeral 23 denotes an oil supply cylinder for connecting and connecting the oil supply hose 21.
24 is a motor section arranged at the lower end of the oil supply cylinder 23, 24a is an impeller linked to the output shaft 24b of the motor section 24, 25 is a battery case, 25a is a circuit section provided in the battery case 25, 26
Is a lead wire that connects the battery case 25 and the motor unit 24.

When the kerosene is transferred to the kerosene can by the oil supply pump P, the kerosene sucked up from the oil supply cylinder 23 is supplied from the oil supply hose 21 into the kerosene can. L1 and L2 indicate liquid level.

As described in the conventional example (see FIG. 10), the liquid level detecting sensor A comprises the light switch 11, the sensor lens 3, and the light receiving element 12 as an optical switch S, which is indicated by a solid line in FIG. At the liquid level L1 shown, the optical switch S of the liquid level detection sensor A is in the air, and the light from the light emitting element 11 emits light from the light emitting element 11 → first reflecting surface 3a → second reflecting surface 4a → light receiving element. An optical signal path 71 is formed by connecting with 12, and the optical switch S is closed and is in an ON state.

On the other hand, at the liquid level L2 indicated by the one-dot chain line, the sensor lens 3 of the optical switch S comes into contact with the liquid surface, and the light from the light emitting element 11 undergoes normal refraction reflection from the first reflection surface 3a. Without it, it is not transmitted to the light receiving element 12. Therefore, the optical switch S is opened and turned off, and the liquid level L
And the motor unit 24 is stopped by the detection signal and the supply of kerosene is stopped.

In such a liquid level detecting sensor A,
The gist of the present invention resides in that the sensor lens 3 is configured to allow infrared rays to pass therethrough while reducing the amount of visible light entering as much as possible, and the sensor lens 3 is colored with a smoke color or the like. It is made of transparent material.

As described above, since the sensor lens 3 is formed of the smoked colored transparent material, when the liquid surface level detection sensor A tries to detect the liquid surface level L2, the visible light which is a disturbance is externally applied. Even if it comes in, the external light, which is such a visible light, is greatly dimmed by the sensor lens 3, so that it is possible to prevent malfunction due to visible light, and the detection accuracy is significantly improved.

In this embodiment, as shown in FIGS. 2 and 3, the sensor lens 3 is integrally formed on one side wall of the element casing 1, and the entire element casing 1 including the sensor lens 3 is irradiated with infrared rays. It is made of a smoke-colored hard synthetic resin that transmits and reduces the penetration of visible light as much as possible.

Therefore, the sensor casing 20 can be easily incorporated into the sensor casing 20 and the manufacturing cost can be reduced. Although a hard synthetic resin is used as the colored and transparent material in this embodiment, glass or the like may be used.

In general, infrared rays, which is a kind of electromagnetic waves, have a wavelength of 750 nm to 400,000 nm, and below that, visible rays have a wavelength of up to 380 nm.

Infrared light L is used for the light emitting element 11 in this embodiment.
The ED is used, and the wavelength of infrared rays emitted is 940 nm.
Is.

FIG. 4 shows the light transmittance when the sensor lens 3 in this embodiment is used. The thick line a represents the case of the sensor lens 3 used in this example, and the thickness t from the side wall 2 of the element casing 1 to the ridge line 9 of the sensor lens 3 is 2 mm.

As is apparent from FIG. 4, when the sensor lens 3 of the liquid surface level detection sensor A according to this embodiment is made of smoke-colored hard synthetic resin, visible light is 20% or less. The transmittance is about 90% for infrared rays.

The thin line b indicates that the thickness t from the side wall 2 of the element casing 1 to the ridge line 9 of the sensor lens 3 is 3 mm, and in this case, the visible light transmittance is 10% or less. Has become. And for infrared,
Similar to the case of 2 mm, the transmittance is about 90%.

As described above, FIG. 4 simply shows that visible light does not act as a disturbance.

By the way, when the refueling pump P is actually used, it is the sunlight that enters as a disturbance, but the sunlight also contains infrared rays. However, the contained infrared rays are dimmed by the sensor casing 20 and become extremely weak, so that they hardly affect the sensor function.

If the transmittance of visible light is 20% or less, the disturbance effect of visible light can be sufficiently prevented, and the thickness t of 2 mm is sufficient for downsizing the element casing 1.

As described above, when the liquid surface level detection sensor A tries to detect the liquid surface level L2, even if visible light which is a disturbance comes in from the outside, the amount of light passing through the sensor lens 3 is extremely large. It is possible to prevent the malfunction due to visible light that the optical switch S is turned on even when the liquid surface reaches a predetermined height.

Further, according to the present invention, the light emitting element 11 and the light receiving element 12 are provided.
And the light emitting element 11 are arranged in the element assembly 10.
Is coated with transparent coating material 10a, while the
It is also characterized in that 12 is coated with a black coating material 10b.

That is, as shown in FIG.
100% of the light can be extracted by coating with a transparent resin as the transparent coating material 10a.
Is coated with a black resin as the black coating material 10b to surely block visible light and function as a filter that transmits only infrared rays. The infrared transmittance of the black resin is 80% in this embodiment.

As described above, the smoked sensor lens 3 for reducing visible light as a disturbance and the element assembly 10 in which the light emitting element 11 is coated with a transparent resin and the light receiving element 12 is coated with a black resin are used to emit light. Infrared rays from the element 11 are taken out to the maximum to form an accurate optical signal path 8 and at the same time, visible light is surely prevented from entering the light receiving element 12. Therefore, it can be remarkably highly accurate as compared with the conventional liquid level detection sensors X and Y.

As a result of the experiment, it has been confirmed that the liquid level detecting sensor A of this embodiment has no malfunction at the illuminance of 4,800 lx to 40,000 lx.

As described above, even if a visible ray that becomes a disturbance comes in from the outside, the amount of the visible ray transmitted through the sensor lens 3 is extremely small, and the transmitted visible ray is much more than the light forming the optical signal path 8. Moreover, since the black resin does not reach the light receiving element 12, the malfunction that the optical switch S is in the ON state even when the liquid surface reaches a predetermined height can be reliably prevented.

Therefore, the function as the sensor can be surely fulfilled, and the highly reliable and high performance liquid level detecting sensor A can be supplied.

Further, in the present embodiment, since the element casing 1 is also colored in smoke, not only the sensor lens 3 but also the amount of visible light that is a disturbance from entering the element casing 1 can be reduced. The liquid level can be detected.

In this embodiment, the element casing 1 and the sensor lens 3 are made of smoke-colored hard synthetic resin, but the same effect can be obtained even if only the sensor lens 3 is smoked.

In this embodiment, the liquid level detecting sensor A is used for the electric oil supply pump P, but it can be applied to other pump devices such as an electric pump for filling a bathtub with water. .

Next, another embodiment shown in FIG. 6 will be described.

This is a two-color molding of the entire element casing 1 including the sensor lens 3.
Here, only the portion 31 capable of ensuring the minimum area for constructing the optical switch S is formed of a smoke-colored transparent material, and the other is molded of a colored material that does not transmit light. Synthetic resin is used as the material.

In the liquid level detecting sensor A incorporating the element casing 1, the area through which light is transmitted is small,
Invasion of visible light, which becomes a disturbance, can be prevented as much as possible, and the detection accuracy is further improved as compared with the previous embodiment.

In particular, if the light-receiving element 12 is combined with the one coated with the black coating material 10b, the light-receiving element 12 operates reliably even if the illuminance of the sunlight (about 110,000 lx) in the outdoors during fine weather, and there is a risk of malfunction. Absent.

FIG. 7 shows a liquid surface detector B to which the liquid surface level detection sensor A of this embodiment is applied.

The liquid level detector B is the element casing 1
A sensor lens 3 formed in the element casing 1 is constructed by inserting a plurality of element assemblies 10 vertically arranged at regular intervals in the sensor casing 20.
Is molded in two colors as described above.

Then, each element assembly 10 is connected to a controller (not shown) so that the liquid level can be detected for each element assembly 10.

According to the liquid level detector B having the above structure, the capacity of the outdoor tank or the like can be accurately and easily monitored, for example, in units of centimeters by setting the interval between the element assemblies 10. It is also possible to emit a signal at a predetermined liquid level depending on the control method.

When combined with a pump or the like, the pump can be surely stopped at any liquid level as in the previous embodiment.

Moreover, as compared with an ultrasonic measuring instrument or the like which has been conventionally used for liquid level detection, calibration at the time of measurement is unnecessary, the operation is simple, and the cost is far advantageous.
It can be widely applied in fields requiring precise liquid level detection such as industrial use.

The liquid level detecting sensor A according to the present invention has the element casing 1 or the sensor lens 3 in addition to the ones shown in the above-mentioned two embodiments. Etc.), followed by coloring to prevent the entry of visible light, or
It is also possible to attach various colored films.

In this case, the conventional liquid level detecting sensor X,
Even with Y etc., the accuracy can be improved by a simple method.

[0079]

EFFECT OF THE INVENTION A sensor lens formed of an optical prism that refracts and reflects light, and a light emitting element that emits light and a light receiving element that receives light from the light emitting element are arranged in parallel at a position facing the sensor lens. In the liquid level detection sensor which is provided with an optical signal path between the light emitting element and the light receiving element via the sensor lens, the sensor lens allows infrared rays to pass therethrough, and the amount of visible light penetrating therethrough. Since the liquid level detection sensor attempts to detect the liquid level, it is possible to reduce the The light is greatly dimmed by the sensor lens, a malfunction due to visible light can be prevented, and the detection accuracy can be significantly improved.

Since the sensor lens is made of a colored transparent material such as smoked color, the
The transmittance is less than or equal to%, while the infrared ray is about
With a transmittance of 90%, it is possible to prevent visible light from acting as a disturbance as much as possible.

By attaching a colored or colored film to the sensor lens, it is possible to prevent erroneous operation due to visible light even in the existing liquid level detection sensor, and it is possible to remarkably improve the detection accuracy.

A sensor lens is provided along the axial direction inside the sensor casing, the light emitting element and the light receiving element are arranged in parallel at a position facing the sensor lens, and a light emitting element is provided via the sensor lens. By forming the optical signal path that optically couples with the light receiving element on the surface orthogonal to the axial direction of the sensor casing, it is possible to further improve the detection accuracy without depositing drops on the sensor lens that constitutes the optical switch. You can

A sensor lens is integrally formed on one side wall of a cylindrical element casing that houses the light emitting element and the light receiving element, and the entire element casing including the sensor lens is
Since infrared rays are transmitted and visible rays are prevented from entering as much as possible, the infrared rays can be easily incorporated into the sensor casing and the manufacturing cost can be reduced.

Further, not only the sensor lens but also the amount of visible light penetrating from the element casing can be reduced, and the detection accuracy can be further improved.

Since the entire element casing including the sensor lens is made of a smoke-colored synthetic resin which transmits infrared rays and reduces the penetration of visible rays as much as possible, the manufacturing cost can be reduced and the reliability can be improved. It is possible to supply a high level liquid level detection sensor at a low price.

By disposing the light emitting element and the light receiving element in the element assembly, and coating the light emitting element with the transparent coating material, while coating the light receiving element with the black coating material, infrared rays from the light emitting element can be prevented. An accurate optical signal path can be formed by taking out to the maximum, and in addition, visible light can be reliably prevented from entering the light-receiving element, and a highly accurate liquid level detection sensor without malfunction can be supplied.

[Brief description of drawings]

FIG. 1 is an explanatory diagram of an oil supply pump including a liquid level detection sensor according to the present invention.

FIG. 2 is an explanatory diagram showing an element casing of the liquid level detection sensor.

FIG. 3 is a vertical sectional view of the element casing.

FIG. 4 is a graph showing the transmittance of a sensor lens in visible light and infrared light.

FIG. 5 is an explanatory diagram of an element assembly.

FIG. 6 is an explanatory diagram showing an element casing of a liquid surface level detection sensor according to another embodiment.

FIG. 7 is an explanatory diagram showing an application example of the liquid level detection sensor.

FIG. 8 is a vertical cross-sectional view of a detection unit of a conventional liquid level detection sensor.

FIG. 9 is an explanatory view showing the lens casing.

FIG. 10 is a cross-sectional view of the element casing.

FIG. 11 is an explanatory diagram showing one form of a conventional liquid level detection sensor.

[Explanation of symbols]

 1 element casing 3 sensor lens 8 optical signal path 10 element assembly 10a transparent coating material 10b black coating material 11 light emitting element 12 light receiving element 20 sensor casing A liquid level detection sensor

Continuation of the front page (56) References JP-A-53-131071 (JP, A) JP-A-59-63396 (JP, A) JP-A-58-28626 (JP, A) Jitsukaihei 2-25831 (JP , U) Actual development Sho 60-29239 (JP, U)

Claims (8)

(57) [Claims] 1. A sensor lens (3) formed of an optical prism that refracts and reflects light, and a light emitting element (11) and a light emitting element (11) that emit light at a position facing the sensor lens (3). )
A light receiving element (12) for receiving the light from is arranged in parallel, and an optical signal path (8) is formed between the light emitting element (11) and the light receiving element (12) through the sensor lens (3). In the liquid level detection sensor, the sensor lens (3) is configured to allow infrared rays to pass therethrough while reducing the amount of visible light entering as much as possible. . 2. The liquid level detecting sensor according to claim 1, wherein the sensor lens (3) is made of a colored and transparent material such as smoked color. 3. A colored or colored film is attached to the sensor lens (3).
Liquid level detection sensor described. 4. The sensor lens (3) is provided along the axial direction in the sensor casing (20), and the light emitting element (11) and the light receiving element (11) are provided at positions facing the sensor lens (3). 12) and are installed side by side, through the sensor lens (3),
Optical signal path that optically couples the light emitting element (11) and the light receiving element (12)
The liquid level detection sensor according to any one of claims 1 to 3, wherein (8) is formed on a surface orthogonal to the axial direction of the sensor casing (20). 5. The sensor lens (3) is connected to the light emitting element.
Cylindrical element casing that houses (11) and light receiving element (12)
(1) is integrally formed on one side wall of the element casing (1) including the sensor lens (3) to transmit infrared rays, and
The liquid level detection sensor according to any one of claims 1 to 4, wherein the visible light is configured to reduce its intrusion as much as possible. 6. The sensor lens (3) is connected to the light emitting element.
Cylindrical element casing that houses (11) and light receiving element (12)
(1) It is integrally formed on one side wall, and only the part for forming the optical signal path (8) is made of a colored transparent material such as smoke color, while the other part is made of a colored material that does not transmit light. The liquid level detection sensor according to claim 4, which is formed by two-color molding. 7. The element casing (1) including the sensor lens (3) is formed of a smoke-colored synthetic resin that transmits infrared rays and reduces the penetration of visible rays as much as possible. The liquid level detection sensor according to claim 4 or 5. 8. The light emitting element (11) and the light receiving element (12) are arranged in an element assembly (10), and the light emitting element (11) is coated with a transparent coating material (10a). Light receiving element
The liquid level detection sensor according to any one of claims 1 to 7, wherein (12) is coated with a black coating material (10b).