JPH05273121A - Liquid sensor - Google Patents

Abstract

PURPOSE:To accurately and easily detect the contamination of a liquid such as oil. CONSTITUTION:Light emitting elements 2a, 2b and a light receiving element 3 are arranged in a case 71, and a reflecting face 73 is formed on the face faced to a detecting face arranged with these elements. The light emitting elements 2a, 2b generate the light having two different luminescence wavelength peaks. One is the light having the preset wavelength transmitted constantly regardless of the contamination of a liquid, and the other is the light having the wavelength absorbed in relation with the contamination of the liquid. The case 71 is inserted into the liquid, light is radiated into the liquid from the light emitting elements 2a, 2b in sequence, then the reflected light is received by the light receiving element 3, and the intensity of the light is compared between the wavelengths to obtain the difference. The degree of contamination can be accurately measured regardless of the coloring of the liquid.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid sensor for detecting the degree of contamination of liquids such as machine working oils for machines, oils for vehicles such as engines, missions, differentials, cooling drains and other machine lubricating oils.

[0002]

2. Description of the Related Art Lubricating oil of an internal combustion engine is oxidized by being exposed to a high temperature on a cylinder wall and a piston or by contacting with a high temperature combustion gas. When the oil oxidizes, various oxides and gum-like substances are produced, which increases the acid value and clay of the oil and deteriorates the quality. Also, these oxides corrode the bearing metal and enhance wear. For this reason, for example, in automobiles, engine oil is regularly inspected and replaced. Also, machine oils and lubricating oils of machines will oxidize due to long-term use and will be mixed with machine scraps, so they should be replaced regularly.

Such oil inspection is generally carried out by taking out the oil and measuring it with a color spectrometer. In the case of engine oil, the color and adhesion of the oil attached to the level gauge for checking the oil level are visually checked. However, since such an inspection work cannot directly inspect the oil, the work is troublesome, and an accurate measurement cannot be performed because a little oil attached to the level gauge is used.

Further, when the liquid is originally colored like engine oil, it is difficult to distinguish the original color from the color change caused by the stain of the liquid, and accurate measurement cannot be performed.

[0005]

An object of the present invention is to solve the above conventional problems, and an object of the present invention is to provide a liquid sensor capable of accurately and easily detecting dirt of liquid such as oil.

[0006]

A liquid sensor according to the present invention for achieving the above object includes a light emitting means for generating light having at least two different emission wavelength peaks, and a liquid irradiated from the light emitting means. Liquid contamination is determined based on the difference in the intensity of the light captured by the light receiving means for each of the light of different wavelengths, and the detection means that has the light receiving means that captures the light of different wavelengths that has been reflected inside or transmitted through the liquid. In one aspect, the detection unit has a detection unit in contact with the liquid, and the detection unit includes a light emitting unit, a detection surface on which the light receiving unit is provided, and the light emitting unit. A detecting surface and a reflecting surface which are arranged to face each other with a liquid interposed; and as another aspect, the detecting portion is a light emitting surface on which a light emitting means is provided. And the light emitted from the light emitting means And a light-receiving surface of light receiving means for receiving the light transmitted through the body are arranged, the light receiving surface and these light-emitting surface are those which are disposed to face each other interposing a liquid. Further, the detection section may be connected to the light emitting means and the light receiving means by an optical fiber.

[0007]

By using light of a predetermined wavelength that constantly transmits regardless of the dirt of the liquid and light of a wavelength that is absorbed in association with the dirt of the liquid, these lights are reflected in the liquid after being irradiated. The intensity of the light or the light transmitted through the liquid is compared and the difference is calculated. This makes it possible to accurately measure the degree of contamination regardless of the coloring of the liquid.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the liquid sensor of the present invention will be described below with reference to the drawings. Oil sensor 1 which is a liquid sensor
Reference numeral 0 denotes a light emitting element 2 which is a light emitting means mounted on the circuit board 1 as shown in FIG. 1, a light receiving element 3, and a power supply and a circuit for driving and controlling these, and further from the light receiving element 3 The determination circuit 4 for determining the contamination of the liquid based on the signal and the display unit 5 for displaying the result determined by the determination circuit. The determination circuit 4 and the display unit 5 may be integrated with the circuit board 1 to form one sensor. The light emitting element 2 and the light receiving element 3 are connected to a detection unit 7 that is in direct contact with the liquid via an optical fiber 6. The detection unit 7 is brought into contact with the oil 9 stored in a container 8 such as an oil tank or an engine room.

The light emitting element 2 is a combination of two types of LEDs which emit different kinds of light. One of the LEDs has a wavelength which has a certain transmissivity with respect to a liquid to be applied regardless of the state of dirt, for example, light having a wavelength. It is a red LED that emits light with a peak emission wavelength of 660 nm when the liquid is engine oil. The other LED is an infrared LED that emits light having a wavelength that can be absorbed by liquid stains, for example, infrared light having a wavelength of 880 nm or 940 nm. The light receiving element 3 has a high sensitivity to light having such a wavelength, and for example, PI
An N silicon photodiode or the like can be used.

Further, as shown in FIG. 2A, the detecting section 7 has a case 71 made of plastic or the like at the tip 6a of the optical fiber 6.
Is attached, and a red LE is attached to the tip of the case 71.
A window 72 made of a material that transmits the light of each of D and the infrared LED
(Detection surface) is formed, and a reflection surface 73 is formed at a position facing the window 72. Therefore, the contamination of the liquid is performed by measuring the light that is irradiated from the optical fiber tip 6a through the window 72 to the liquid and reflected by the reflection surface 73.

A method for measuring oil stains in such a configuration will be described. The detector 7 is inserted into the oil 9 contained in the container 8 at an appropriate angle (for example, 75 degrees with respect to the oil surface) to an appropriate depth. When the red LED is turned on in this state, predetermined light passes through the optical fiber 6 and is irradiated from the tip 6a of the liquid to the liquid through the window 72, is reflected by the reflection surface 73, and is captured by the light receiving element 3 through the fiber 6. Be done. The light captured by the light receiving element 3 is constant regardless of the dirt of the oil, and the signal S1 corresponding to the intensity of the light is sent to the determination circuit 4. Next, when the infrared LED is turned on, predetermined light is similarly reflected by the reflecting surface and the light receiving element 3
Captured by. The intensity of the reflected light from this infrared LED is
When the oil is not dirty, the intensity of the reflected light from the red LED is the same because it is not absorbed by the dirt, and the signal S2 (= S1) of the same intensity is sent to the determination circuit 4. When the oil is dirty, the light from the infrared LED is absorbed in correlation with the dirt, and the signal S2 corresponding to the intensity of the reflected light becomes smaller than the signal S1 for the red LED.

The decision circuit 4 takes the difference between these signals and outputs S2
In the case of <S1, it is determined that there is dirt and a signal is sent to the display unit 5 to be displayed. It is also possible to previously obtain the correlation between the signal difference (S1−S2) and the degree of dirt, and display the presence of dirt when the difference (S1−S2) exceeds a predetermined threshold value. Further, the degree of contamination may be displayed based on the difference (S1-S2).

In the above description, the light emitting element (light receiving element) is connected to the detecting portion 7 via the optical fiber, but as shown in FIG. 2B, light having different wavelengths is generated. The two light emitting elements 2a and 2b and the light receiving element 3 may be directly housed in the case 71 'for measurement. In this case, the liquid sensor can be configured by being housed in the case integrally with the circuit portion formed on the substrate 1, and only the tip of the detection unit in which the light emitting elements 2a and 2b and the light receiving element 3 are embedded. Can be inserted into the liquid and its dirt can be detected.

In all of the above embodiments, the stain is detected based on the light reflected in the liquid, but the liquid sensor of the present invention may measure the light transmitted through the liquid. Such a configuration is shown in FIG. FIG. 3 shows a detection part of a liquid sensor, and the detection part includes two light emitting elements 2 which generate light of different wavelengths in a case 70 inserted in a liquid.
a and a light emitting surface on which the light emitting elements 2a are provided,
A light receiving surface on which a light receiving element 3 for receiving light from 2b is disposed is formed, and the light emitting surface and the light receiving surface are provided so as to face each other with a liquid in between. Therefore, in the light emitted from one light emitting element 2a, the remaining light absorbed by the absorption of the liquid itself and the absorption corresponding to the stain is captured by the light receiving element 3, and the other light is emitted.
In the light emitted from b, the light absorbed by the absorption of only the liquid itself is captured by the light receiving element 3, and the degree of contamination can be detected by taking the difference in the intensities of the two lights.

Also in this case, the light emitting element and the light receiving element may be housed together with other circuit parts in the case, or may be connected to the detecting portion via an optical fiber. The shape can be appropriately changed depending on the application and the like. Although the measurement of oil stains has been described above, the liquid sensor of the present invention can detect not only oil stains but also other liquid stains such as radiator water by selecting light of an appropriate wavelength. Needless to say.

[0016]

As is apparent from the above embodiments, according to the liquid sensor of the present invention, two kinds of light having different wavelengths are used and the light is reflected by the liquid or transmitted through the liquid. Since the liquid stain is detected by the difference in the intensity of the liquid, it is possible to easily and accurately detect the liquid stain. Further, according to the liquid sensor of the present invention, since the detection unit to be injected into the liquid and the light-emitting and light-receiving units are connected by the optical fiber, even if the liquid is stored in any place, its contamination is always easy. Can be detected.

[Brief description of drawings]

FIG. 1 is an overall view showing one embodiment of a liquid sensor of the present invention.

FIG. 2 is a cross-sectional view showing a main part of the liquid sensor of FIG.
FIG. 6A is a diagram showing a detector connected by an optical fiber, and FIG. 9B is a diagram showing a detector directly attached with a light emitting element and a light receiving element.

FIG. 3 is a diagram showing a main part of another embodiment of the liquid sensor of the present invention.

[Explanation of symbols]

 2 ... Light emitting element (light emitting means) 3 ... Light receiving element (light receiving means) 4 ... Judgment circuit (judging means) 6 ... Optical fiber 7 ...・ ・ ・ ・ ・ Detector 72 ・ ・ Window (detection surface) 73 ・ ・ Reflective surface

Claims (4)

[Claims] 1. A light emitting means for generating light having at least two different emission wavelength peaks, and a light receiving means for capturing light of different wavelengths which is emitted from the light emitting means and reflected in the liquid or transmitted through the liquid. A liquid sensor, comprising: a detection unit including: and a determination unit that determines a liquid stain based on a difference in light intensity captured by the light receiving unit for each of the different wavelengths of light. 2. The detecting means has a detecting portion that comes into contact with the liquid, and the detecting portion reflects the light emitted from the light emitting means and the detecting surface on which the light receiving means is arranged. The liquid sensor according to claim 1, wherein the liquid sensor has a surface, and the detection surface and the reflection surface are arranged to face each other with the liquid interposed. 3. The detecting means has a detecting portion that comes into contact with the liquid, and the detecting portion has a light emitting surface on which the light emitting means is disposed and light emitted from the light emitting means that has passed through the liquid. 2. The liquid sensor according to claim 1, further comprising a light receiving surface on which a light receiving means for receiving the light is disposed, and the light emitting surface and the light receiving surface are opposed to each other with the liquid interposed. .. 4. The liquid sensor according to claim 2, wherein the detector is connected to the light emitting means and the light receiving means by an optical fiber.