JPH0249143A - Detector for liquid mixing ratio of mixed liquid - Google Patents

Abstract

PURPOSE:To detect with high accuracy a mixing ratio of mixed fuel by providing a light emitting element and a light receiving element through a light transmissive body on a part of a housing which said fuel passes through and measuring the light quantity which is refracted by said fuel and made incident by said light receiving element. CONSTITUTION:Infrared rays 32 emitted from a light emission diode 3 advance in a silicone resin 31 and flint glass 1 (transmissive body), is limited to a set incidence or below by a mask 4, refracted by the boundary surface of the wall surface 11 of the fling glass 1 and mixed fuel 92, and advance in the mixed fuel 92. Subsequently, said infrared rays are refracted by the boundary surface of the mixed fuel 92 and the flint glass 2, and made incident on an output photodiode 5. An output of the photodiode 5 increases or decreases in accordance with a refractive index of the mixed fuel 92, therefore, by detecting the output of this diode, a mixing ratio of said mixed fuel can be detected. Also, a compensation light receiving element 6 always receives said refracted light and controls the light quantity of the light emission diode 3 so that its output becomes constant.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a detector that optically detects the mixed fuel ratio of an engine that uses a mixture of two or more different fuels.
In particular, the present invention relates to a detector suitable for detecting the mixing ratio of a mixed fuel of gasoline and alcohol.

[Prior Art] Attempts are being made in various fields to mix alcohol fuel produced from natural gas, coal gas, or biomass with gasoline as an alternative fuel to gasoline and use it in existing internal combustion engines. If this alcohol-mixed gasoline is used as is, it may not operate properly due to differences in the stoichiometric air-fuel ratio, etc., or it may increase the generation of NOx, HC, Co, etc., so the mixture ratio should be detected appropriately to determine the optimal injection amount. There is a need to.

As a technology for detecting this mixing ratio, the patent applicant has
Patent Application No. 1983-22578 (Conventional Example 1), Patent Application No. 1982-
No. 43960 (Conventional Example 2) and the like are proposed. In these technologies, the mixing ratio of gasoline and alcohol to be measured is adjusted by using the fact that the critical angle at the interface between the transparent body and the measured liquid changes, and the light emitted from the light emitting element is It was determined from the change in the amount of light incident on the light receiving element by causing total reflection on the surface and returning to the light receiving element.

[Problem to be solved by the invention] However, the conventional technology has the following drawbacks.

(I) When bubbles are present in the liquid to be measured, the amount of change in the output value of the light receiving element is very large (Conventional Examples 1 and 2).

(II) It is necessary to place a transparent body protruding into the flow path of the liquid to be measured, which makes it difficult to attach and seal the transparent body, and if the liquid to be measured is flowing, it may disturb the flow. As a result, bubbles are likely to be generated (Conventional Example 1).

<III) Dimensional accuracy is required in terms of the distance between the light emitting element and the light receiving element, the size of the light receiving element, etc. (Conventional Example 1.2).

SUMMARY OF THE INVENTION An object of the present invention is to provide a liquid mixture ratio detector for a mixed liquid, which has a small error in measuring the mixture ratio even when bubbles are present in the liquid to be measured.

[Means for Solving the Problems] In order to achieve the above-mentioned problems, the present invention provides a housing that is disposed flush with the inner wall surface of a housing grooved with a liquid to be measured which is a mixture of two or more types of liquids. a first light transmitting body having a first wall surface; a light emitting element disposed on the other wall surface side of the first light transmitting body;
an incident angle limiting means for limiting an incident angle from the light emitting element to the first light transmitting body to only light that is equal to or less than a set incident angle; , a second light transmitting body having a second wall surface disposed flush with the inner wall surface of the housing; a light receiving element disposed on the other wall surface side of the second light transmitting body; a compensating light-receiving element disposed on the other wall surface side of the light-transmitting body of No. 2 and on the side closer to the light-emitting element; The relationship between the mounting position and the compensation light-receiving element is as follows: (a) The light from the light-emitting element travels through the first transparent body, and the incident angle becomes equal to or less than the set incident angle by the incident angle limiting means. It is refracted at the interface between the first wall surface of the first transparent body and the liquid to be measured, travels through the liquid to be measured, is refracted at the boundary between the liquid to be measured and the second transparent body, and the The light traveling through the second transparent body is incident on the light receiving element, and the output of the light receiving element is set to be increased or decreased according to the refractive index of the liquid to be measured. It is set so that light at the maximum incident angle of the incident light limited by the incident angle limiting means is made incident on the light receiving element over the entire range of refractive index,
(c) The compensating light-receiving element always receives refracted light, and the light intensity of the light-emitting element is controlled so that its output is constant.

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

■If there are bubbles in the liquid to be measured, in most cases, the light that passes through the bubbles will simply shift the position of the light that passes through the bubbles, and the amount of light received by the light-receiving element will change. No change occurs. Therefore, even if bubbles are present in the liquid to be measured, there is little error in measuring the mixing ratio.

■Since the detector is arranged flush with the inner wall surface of the housing, it is easy to attach the transparent body and has excellent sealing performance. Furthermore, when the liquid to be measured is flowing, bubbles are less likely to occur because the flow is not disturbed.

0 Precise dimensions are not required for the position and spacing of the light-emitting element and the light-receiving element, the size of the light-receiving element, etc.

[Example] Next, the present invention will be explained based on an example shown in FIGS. 1 and 2.

As shown in FIG. 1, the liquid mixture ratio detector A for mixed liquids of the present invention has a flint glass 1.2 disposed flush with the inner wall surface 91 of the pipe 90, and the wall surface 11.21 is arranged flush with the inner wall surface 91 of the pipe 90. A light emitting diode 3 and a mask 4 are arranged on the other wall surface 12 side exposed to the mixed fuel 92, and another end surface 22 is exposed to the mixed fuel 92.
An output photodiode 5 and a compensation photodiode 6 are arranged on the side. The pipe 90 also connects a mixed fuel tank and a pressure regulator (both not shown).
It is a pipe that connects the

The flint glass 1.2 is a disc-shaped transparent material with a refractive index of 1°55, and has a cut hole 93 formed through the pipe 90.
is fixed in a liquid-tight manner.

The light emitting diode 3 is of the gallium arsenide type and emits infrared light. The light emitting diode 3 is molded with a transparent silicone resin 31 and is fixed in the cut hole 93 with a spacer 94 and a cover plate 95. Infrared light 3
2 becomes the optical path 33 when the refractive index of the mixed fuel 92 is maximum, and becomes the optical path 34 when it is the minimum.

The mask 4 is formed of a light-shielding material and has a substantially donut shape, and is connected to the other wall surface 12 of the flint glass 1 and the silicone resin 31.
and the inner edge of the inner edge.

Furthermore, this mask 4 is located above the optical path 34 shown by the dotted line in FIG. 1 when the mixed fuel 92 has the minimum refractive index).
However, the incident light from the output photodiode 5 is restricted so that it does not protrude from the end 51.

In the output photodiode 5, the infrared light 32 emitted from the light emitting diode 3 travels through the silicone resin 31 and the flint glass 1, becomes less than the set incident angle from the mask 4, and reaches the wall surface 11 of the flint glass 1 and the mixed fuel 92. The mixed fuel 92 is refracted at the interface between the flint glass 2 and the flint glass 2.
Injection is performed by proceeding inside. Further, the output of the output photodiode 5 is increased or decreased depending on the refractive index of the mixed fuel 92.

The compensation photodiode 6 always receives infrared light 35 and (
A) The sensitivity of the light emitting diode 3 and the output photodiode 5 changes depending on the temperature, and (b) The amount of light from the light emitting diode 3 decreases due to aging of the light emitting diode 3, dirt on the flint glass 1.2, etc. It is arranged to compensate. The above (a) and (b) are compensated by controlling the amount of current flowing through the light emitting diode 3 so that the output of the compensation photodiode 6 is constant. Further, compensation for the fact that the refractive index of the mixed fuel 92 changes by approximately -4×10-'/'C is achieved by utilizing the temperature characteristics of the voltage drop of the light emitting diode 3.

The liquid mixture ratio detector A of the present embodiment has the following functions and effects.

■When air bubbles 96 exist in the mixed fuel 92 as shown in FIG.
For example, the change in the output of the output photodiode 5 is minimal, simply by shifting the position where the infrared light 32) directly enters the output photodiode 5 (to form an optical path 36).

Therefore, even if there are bubbles 96 in the mixed fuel 92,
There is little error in measuring the mixing ratio.

(2) Since the detector A is arranged flush with the inner wall surface 91 of the pipe 90, it is easy to attach the flint glass 1.2 and has excellent sealing performance. Furthermore, since the flow of the mixed fuel 92 is not disturbed, bubbles 96 are less likely to occur.

(2) Since the mixture ratio of the mixed fuel 92 is detected by the refractive index, precise dimensions such as the position, spacing, and size of each element are not required.

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

a. Placing it flush with the inner wall surface of the housing means that
This includes a case where the first and second light-transmitting bodies are misaligned with the inner wall surface of the housing.

b. Two or more types of liquids are any two types of liquids whose mixing ratio changes, may be liquids other than fuel, have free direction of flow, and are in a stationary state. Also good.

C1 The mixed fuel 92 used in the above embodiment may be a liquid mixture of gasoline and a composite alcohol containing ethanol, MTBE, butanol, or other higher alcohols, or a liquid mixture of the above alcohols and light oil.

The light used by the 60 light-emitting element and the light-receiving element is preferably of a single color, and the wavelength is not particularly limited.

e. The silicone resin may be any transparent material, such as epoxy resin.

f. The light transmitting body is not limited to glass such as flint glass, but may also be a transparent resin as long as it is not affected by the liquid to be measured.

[Brief explanation of the drawing]

FIG. 1 shows an embodiment of the liquid mixture ratio detector for mixed liquid of the present invention, and is a cross-sectional view showing the state in which it is installed through a pipe through which mixed fuel flows, and FIG. FIG. 3 is a cross-sectional view for explaining the operation of the detector when bubbles are present in the mixed fuel. In the figure 1...Flint glass (first transparent body) 2...
・Flint glass (second transparent body) 3... Light emitting diode (light emitting element) 4... Mask (incident angle limiting means) 5... Photodiode for output (light receiving element) 6
...Compensation photodiode (compensation light receiving element) 1
1...Wall surface (first wall surface) 12.22...Other wall surface 21...Wall surface (second wall surface>90...Pipe (housing) 91...Inner wall surface 92...Gasoline・Alcohol mixed fuel A...Liquid mixture ratio detector for mixed liquid

Claims (1)

[Scope of Claims] 1) A first light-transmitting body having a first wall surface disposed flush with an inner wall surface of a housing filled with a liquid to be measured which is a mixture of two or more types of liquids; , a light emitting element disposed on the other wall side of the first light transmitting body, and an incident angle that limits the incident angle from the light emitting element to the first light transmitting body to only light that is equal to or less than a set incident angle. a restricting means, disposed facing the first transparent body across the liquid to be measured,
and a second light transmitting body having a second wall surface disposed flush with the inner wall surface of the housing; a light receiving element disposed on the other wall surface side of the second light transmitting body; and a compensating light-receiving element disposed on the other wall side of the light-transmitting body and on the side closer to the light-emitting element, and the shape of the light-transmitting body, the incident angle limiting means, the light-emitting element, the light-receiving element, and The relationship between the mounting position and the compensation light-receiving element is as follows: (a) The light from the light-emitting element travels through the first transparent body,
The incident angle becomes equal to or less than the set angle by the incident angle limiting means, is refracted at the interface between the first wall surface of the first light-transmitting body and the liquid to be measured, and travels through the liquid to be measured. The light that is refracted at the interface with the second light-transmitting body and travels through the second light-transmitting body enters the light-receiving element, and the output of the light-receiving element is increased or decreased according to the refractive index of the liquid to be measured. is set to
(b) It is set so that light with the maximum angle of incidence of the incident light limited by the incident angle limiting means is made incident on the light receiving element over the entire range of the refractive index of the liquid to be measured, and (c) Light reception for compensation The element is a liquid mixture ratio detector for a mixed liquid that constantly receives refracted light and controls the amount of light from the light emitting element so that its output remains constant.