JPH02218940A - Detector of liquid mixture rate - Google Patents

Abstract

PURPOSE:To compact a light emitting element by making constitution wherein light from the light emitting element is incident to a light transmission body via a filler and it is reflected on a border surface and outgoes from a peripheral wall when its angle is a critical angle determined by the light transmission body and liquid to be measured or larger. CONSTITUTION:Light from a light emitting element 4 which comes against a light path 41 proceeds in silicon gel 3 and is incident in a glass pillar 2 while the incident angle to a border surface 21 is always a critical angle determined by the glass pillar 2 and mixed fuel 510 or larger, and the light is fully reflected on this critical surface 21, proceeds in the glass column 2, outgoes from a peripheral wall 23 and is incident into a compensating diode 6. Light from the light emitting element 4 which comes against a light path 42 proceeds in the gel 3 and is incident into the glass pillar 2, while the incident angle to the border surface 21 is the critical angle determined by the glass pillar 2 and the fuel 510, and it is fully reflected on the border surface 21, outgoes from the peripheral wall 23 into the gel 3 and is incident into an outputting photo diode 5. A range 43 refers to a light receiving area in a current mixture rate of gasoline and alcohol of the fuel 510, and when the mixture rate varies and the critical angle increases, the light path 42 comes close to the light path 41, thereby narrowing the range 43.

Description

Detailed Description of the Invention [Field of Industrial Application] The present invention relates to a detector for detecting the mixing ratio of a liquid to be measured which is a mixture of at least two types of substances, and particularly relates to a detector for detecting the mixing ratio of a liquid to be measured consisting of a mixture of at least two types of substances, and particularly to a detector that detects the mixing ratio of a liquid to be measured which is a mixture of at least two types of substances. The present invention relates to a detector suitable for detecting.

[Prior Art] In recent years, it has been considered to use a gasoline/alcohol mixed fuel as a gasoline substitute fuel in an automobile internal combustion engine. However, if used as is, it will not run smoothly due to differences in the stoichiometric air-fuel ratio, etc. Therefore, a detector is required to detect the mixing ratio of gasoline and alcohol. For example, as a conventional technology,
2-121547, as shown in FIG. 6, a triangular prism 2 having an interface 210 with a mixed fuel 110 is disclosed.
00, and a light emitting element 300 and a light receiving element 40 are arranged on the other two sides.
A detector equipped with 0 is described.

[Problems to be Solved by the Invention] However, this detector has the following drawbacks. ■
Since a triangular prism is used, the material cost is high. ■
Temperature compensation and compensation for changes in light emitting diodes over time are insufficient, resulting in poor accuracy. For this reason, the applicant of this patent proposed the following detector C in Japanese Patent Application No. 63-295478.

As shown in FIG. 5, the detector C includes a disk-shaped glass 700 whose interface 710 is in contact with gasoline/methanol 600, and a light-emitting diode 810 and a photodiode 820, 830 on the outside of the side surface of the glass 700. are placed facing each other.

However, this detector C also has the following problem.

(A) The thickness of the glass 700 in the axial direction increases, leading to an increase in the weight of the glass 700.

(b) Since the range of light incident on the photodiode 820 is wide, it is necessary to use one with a large light-receiving area.

An object of the present invention is to provide a liquid mixture ratio detector in which the weight of the light transmitting body is reduced and the light receiving element is miniaturized.

[Means for Solving the Problems] To achieve the above object, the present invention employs the following configuration.

(1) A light-transmitting body having a columnar shape and having a boundary surface immersed in a liquid to be measured made of a mixture of at least two types of substances, a holder for holding the light-transmitting body, and a peripheral wall side of the light-transmitting body; a light emitting element disposed at an arbitrary position, at least one light receiving element disposed opposite to the light emitting element with the light transmitting body in between, and a light receiving element disposed between the light transmitting body and the light emitting element and the light receiving element. In a liquid mixture ratio detector comprising a liquid or gel-like light-transmitting filler, the light emitted from the light-emitting element travels through the filler, enters the light-transmitting body, and enters the light-transmitting body. The columnar light beam travels through the light transmitting body, is totally reflected at the boundary surface when the angle is equal to or greater than a critical angle determined by the light transmitting body and the liquid to be measured, travels through the light transmitting body, and is emitted from the peripheral wall or the end face opposite to the boundary surface. The shape of the transparent body and the mounting position of the light receiving element are determined.

■If the structure of ■ is mentioned above, and the filler has a smaller refractive index than the transparent material, and the angle of incidence on the boundary surface is at least equal to or greater than the critical angle determined by the transparent material and the filler, the boundary After being reflected by the surface, it is emitted from the surrounding wall.

[Action and effect of invention] The present invention has the following functions and effects.

<Regarding Claim 1> The light emitted from the light-emitting element travels through the filler, enters the light-transmitting body, travels through the light-transmitting body, and when the angle is equal to or greater than a critical angle determined by the light-transmitting body and the liquid to be measured, the light emitted from the boundary surface The shape of the light-transmitting body and the mounting position of the light-receiving element are determined so that the light is totally reflected at the light-transmitting body, travels through the light-transmitting body, and is emitted from the end face facing the peripheral wall or boundary surface.

Therefore, it is not necessary to emit all of the light totally reflected at the boundary surface from the peripheral wall side of the light-transmitting body into the filler, so that the thickness of the light-transmitting body in the axial direction can be reduced.

Therefore, the light-transmitting body is made lighter. This is advantageous because the holding strength with the holder is reduced.

Regarding Claim 2> (1) The filler has a smaller refractive index than the transparent material. Therefore, as shown in FIG. 2, when the light is emitted from the end face of the transparent body into the filler, the optical path is bent as shown. Therefore, the spread of light incident on the light receiving element in the axial direction due to an increase or decrease in the refractive index of the liquid to be identified is suppressed, and a light receiving element with a small light receiving area can be used.

■If the incident angle to the boundary surface is at least equal to or greater than the critical angle determined by the transparent material and the filling material, it is specified that the incident light is emitted from the peripheral wall after being reflected at the boundary surface. This is to prevent reflection from occurring at the end face facing the .

[Example] Next, a first example (claims 1 and 2) of the present invention will be described based on FIG.

As shown in Figure 1, gasoline/alcohol mixture ratio detector A
1, a metal holder with a circular hole 11 in the bottom;
A glass column 2 loosely fitted into the circular hole 11 and a holder 1
a silicon gel 3 placed inside, a light emitting diode 4 disposed in the silicon gel, an output photodiode 5,
It consists of a compensation photodiode 6 and an adhesive glass ring 7 that joins the glass column 2 and holder 1 together. Further, this detector A is attached via an O-ring 530 to a perforated hole 520 of a pipe 500 through which a gasoline/methanol mixed fuel 510 (refractive index of 1.33 to 1.43) flows.

The metal holder 1 is made of stainless steel.

Further, an annular space of equal width for the glass ring 7 is provided between the circumferential surface of the circular hole 11 and the glass column 2. A resin cylinder 13 is fixed to the bottom surface 1.2 of the metal holder 1.

The glass column 2 is a cylindrical body of flint glass (M refractive index 1.58) with a diameter of 8 mm and a length of 2.5 mm. Reference numeral 21 indicates a boundary surface which is immersed in the mixed fuel 510 and undergoes total reflection, 22 is an end surface opposite to the boundary surface 21, and 23 is a peripheral wall in contact with the inner wall of the glass ring 7.

The silicon gel 3 is a filler that has a refractive index of 1.40 and is transparent. Further, this silicone gel 3 is placed in the metal holder 1 up to the vicinity of the upper opening of the resin cylinder 13.

The light emitting diode 4 is arranged on the inner wall of the resin cylinder 13 at a position slightly below the extension line of the end surface 22.

The output photodiode 5 is arranged on the inner wall of the resin cylinder 13 and across the extension line of the end surface 22 .

The compensation photodiode 6 is disposed on the inner wall of the resin cylinder 13 and below the extension line of the end surface 22 .

The adhesive glass ring 7 is made of flint glass with a wall thickness of 1 nm and a height of 1 mm, and has a softening temperature equal to that of the glass column 2.
It is lower. This glass ring 7 has a protruding boundary surface 21 immersed in the mixed fuel 510 and adheres to the glass column 2 .

Next, the optical path will be explained with reference to FIG.

The light emitted from the light emitting element 4 and falling on the optical path 41 is
It travels through the silicon gel 3 and enters the glass column 2, and the incident angle at the boundary surface 21 is always greater than or equal to the critical angle determined by the glass column 2 and the mixed fuel 510, and at this boundary surface 21. It is totally reflected, travels through the glass column 2, and reaches the surrounding wall 23.
The light is emitted into the silicon gel 3, travels through the silicon gel 3, and enters the compensation photodiode 6.

The light emitted from the light emitting diode 4 and hitting the optical path 42 travels through the silicon gel 3 and enters the glass column 2.The light travels through the glass column 2 and enters the boundary surface 21 at an angle of incidence that is exactly the same as that of the glass column 2 and the mixed fuel 510. is the critical angle determined by
It is totally reflected at this boundary surface 21, travels through the glass column 2, exits from the peripheral wall 23 into the silicon gel 3, travels through the silicon gel 3, and enters the output photodiode 5. In addition, range 4
3 is the light receiving area at the current mixing ratio of gasoline and alcohol of the gasoline/alcohol mixed fuel 510. As the mixing ratio changes, for example the critical angle increases, the optical path 42
approaches the optical path 41 direction, and the range 43 becomes narrower.

Next, the refraction of light at the end face 22 will be explained with reference to FIG.

In this embodiment, the refractive index of the glass column 2 (indicated by a solid line) is greater than the refractive index of the silicon gel 3 which is the enclosure.

Therefore, the optical path 42 of the light from the light emitting diode 4 is as shown by a solid line (θ4>θ3 in FIG. 3).

Here, if the light on the optical path 42 is to be emitted from the peripheral wall 23 into the silicon gel 3, the glass column 2 needs to be large as shown by the broken line 24. In this case, the path of the light becomes an optical path 44 as shown by the broken line, and the emission from the peripheral wall 23 into the silicon gel 3 is as follows (θ1 and θ2 in FIG. 3).

The gasoline/alcohol mixture ratio detector A of this embodiment has the following functions and effects.

(A) When the light in the optical path 42 is emitted from the peripheral wall 23 into the silicon gel 3, the glass column 2 needs to be large as shown by the broken line 24, but in the detector A, the glass column 2 is large as shown by the solid line. It is sufficient to use one of the same size, and the size and weight can be reduced.

(a) With the reduction in weight of the glass column 2, it becomes advantageous in terms of bonding strength when bonded to the metal holder 1.

(1) When the light in the optical path 42 is emitted from the peripheral wall 23 into the silicon gel 3, the optical path 42 becomes broken ff 144, and the incidence on the output photodiode 5 spreads.

In detector A, the optical path 42 follows the path shown by the solid line and does not widen significantly. Therefore, the light receiving area of the output photodiode 5 can be small. Therefore, a small photodiode can be used and the cost of the detector A is reduced. Here, this effect becomes more significant as the difference in refractive index between the silicon gel 3 and the glass column 2 increases. Note that the silicon gel 3 is the glass column 2.
This effect does not occur when the refractive index is equal to or exceeds the refractive index of .

(1) For the above reasons, the length of the glass column 2 in the axial direction can be shortened. Therefore, due to temperature changes, the glass ring 7
Since the stress received from the glass column 2 is reduced, cracking of the glass column 2 is less likely to occur.

Next, a second embodiment (claims 1 and 2) of the present invention will be described based on FIG.

In the detector B of this embodiment, as shown in FIG.
is arranged above the output photodiode 5, and the incident light 45 passes through the silicon gel 3 without passing through the transparent body 2 and enters the compensation photodiode 6. Even with this arrangement, the light emission intensity of the light emitting diode 4 can be monitored regardless of changes in the mixture ratio of the gasoline/methanol mixed fuel 510.

In the detector B of this embodiment, the incident light 45 to the compensation photodiode 6 is not obstructed by the adhesive glass ring 7. Also, the location of the photodiode 6 is the mixed fuel 51.
It is not affected by the critical angle due to a mixing ratio of 0. Therefore, positioning of the photodiode 6 is easy.

The present invention includes the following embodiments in addition to the above embodiments.

a. The refractive index of the light-transmitting body should be determined so that the critical angle with the liquid to be measured is 45° or more, considering the size of the light-transmitting body and the ease of arranging the light-emitting element and light-receiving element. .

61 The light-emitting element and the light-receiving element may be disposed on the peripheral wall side of the light-transmitting body so that they are facing each other, and may be placed inside or outside of the end surface facing the boundary surface.

The liquid to be measured C1 may be a liquid containing different liquids or a liquid in which a solid is dissolved, and may be stationary or flowing.

d. The transparent material may be any material as long as it is not eroded by the liquid to be measured, and soda glass, pyrex glass, borosilicate glass, etc. may be used, and materials other than glass may also be used.

e. Although a cylindrical body was used as the light-transmitting body in the above embodiment for ease of processing, a regular polygonal column may also be used.

f. The holder for holding the light-transmitting body is made of metal in the above embodiment, but it may also be made of ceramic, plastic, or the like, and the holder may be held using a ring.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing a first embodiment of a gasoline/alcohol mixture ratio detector according to the present invention. FIG. 2 is a sectional view of a main part showing the optical path of light in the detector. FIG. 3 is an explanatory diagram showing how light is refracted at the end face of the detector. FIG. 4 is a sectional view showing a second embodiment of the gasoline/alcohol mixture ratio detector according to the present invention. Figure 5 shows the patent application filed in 1983-29, proposed by this patent applicant.
FIG. 5 is a cross-sectional view of a detector described in Japanese Patent No. 5478. FIG. 6 is a sectional view of a conventional detector. In the figure 1...Metal holder (holder) 2...Glass column (translucent body) 3...Silicon gel (filling material) 4.
...Light emitting diode (light emitting element) 5...Output photodiode (light receiving element) 6...Compensation photodiode (light receiving element) 22...End face 23...Peripheral wall 51
0...Gasoline/methanol mixed fuel (liquid to be measured)
A, B...Gasoline/alcohol mixture ratio detector (liquid mixture ratio detector)

Claims (1)

[Scope of Claims] 1) A light transmitting body having a columnar shape and having a boundary surface that is immersed in a liquid to be measured made of a mixture of at least two types of substances; a holder for holding the light transmitting body; a light-emitting element disposed at any position on the peripheral wall side of the light-transmitting body; at least one light-receiving element disposed opposite to the light-emitting element with the light-transmitting body in between; the light-transmitting body; the light-emitting element; and In a liquid mixture ratio detector consisting of a liquid or gel-like light-transmitting filler placed between a light-receiving element and a light-transmitting element, the light emitted from the light-emitting element travels through the filler and enters the light-transmitting body. The light travels through the transparent body, and when the angle is greater than or equal to the critical angle determined by the transparent body and the liquid to be measured, it is totally reflected at the boundary surface, travels through the transparent body, and exits from the peripheral wall or the end face opposite to the boundary surface. A liquid mixture ratio detector characterized in that the shape of the columnar light transmitting body and the mounting position of the light receiving element are determined so as to emit light. 2) The filler has a lower refractive index than the light transmitting material, and if the incident angle to the boundary surface is at least equal to or greater than the critical angle determined by the light transmitting material and the filler, there is no possibility of reflection at the boundary surface. 2. The liquid mixture ratio detector according to claim 1, wherein the liquid mixture ratio detector emits the liquid from the peripheral wall.