JPH04242153A - Liquid mixing-ratio sensor - Google Patents

Abstract

PURPOSE:To prevent peeling of fuse-bonded surface and cracking of a prism by fusing and boding a case and the prism in a broad area by covering the surface of the glass prism other than the reflecting surface with a metal case and fusing and bonding the case with fusing glass. CONSTITUTION:A sensor unit 1 has a cylindrical main-body metal fitting 3 and a prism 4. The lower part of the cylindrical main body metal fitting 3 is coupled into the upper part of bottomed cylindrical housing 2. The prism 4 is fitted into a cylindrical case 41 which is brazed to the tip surface of the metal 3 and fused and bonded with fusing glass 42. The fuse bonding utilizes the difference between the melting point of the fusing glass and the melting point of optical glass. The glass 42 is the fixing means and becomes the sealing means at the same time. Slits in the axial directions are so formed in the tube surface of the case 41 as to face each other. The slits are made to be an incoming window 46 and an outgoing window 47, respectively. Even under the using conditions wherein vibration is applied and the temperature change is large, peeling of fuse-bonded surface, cracking of the prism and the like can be prevented, and the use for a long period can be accomplished.

Description

[Detailed description of the invention]

0001

[Field of Industrial Application] This invention relates to a liquid mixture ratio sensor that measures the mixture ratio of a liquid to be measured, which is a mixture of two or more translucent liquids, using the difference in the refractive index of light. In particular, the present invention relates to a prism holding structure for a liquid (fuel) mixture ratio sensor suitable for installation in an engine that uses a mixed fuel of gasoline and alcohol.

0002

[Prior Art] As a mixture ratio sensor for liquid fuel, etc., light emitted by a light emitting element placed near the prism is incident on a prism whose surface is partially in contact with a liquid to be measured from a surface other than the surface. and reflect it on the partial surface (reflecting surface),
A system has been developed in which light is received by a light receiving element placed opposite to the light emitting element, and the mixing ratio of gasoline and alcohol is detected based on the amount of light received.

[0003] This mixture ratio sensor for liquids such as fuel is required to have durability under usage conditions where vibrations are applied, so it is desirable that the prism be held by a strong metal holder. In addition, since gasoline and alcohol are both highly soluble liquids, they must be kept in constant contact with the liquid being measured.
It is inappropriate to use materials that are easily corroded, such as plastic or rubber. Furthermore, it is important that the device be compact and easy to wear.

0004

Problems to be Solved by the Invention: Optical glass prisms and metal holders have significantly different coefficients of thermal expansion, and elastic materials with excellent sealing properties such as rubber cannot be used due to corrosion resistance. fusion bonding is the most practical. An object of the present invention is to provide a prism holding structure suitable for holding a glass prism by a metal holding means for a long period of time in the above-mentioned liquid mixing ratio detection device under usage conditions where vibrations are applied and temperature changes are large. It's on offer.

[0005]

[Means for Solving the Problems] In order to achieve the above object, the present invention provides a glass prism having a reflective surface that is in contact with a liquid to be measured in which two or more types of translucent liquids are mixed, and a glass prism that directs light into the prism. In an optical liquid mixture ratio sensor that combines a light-emitting element that emits light and a light-receiving element that detects reflected light from a prism, a metal case is placed over the surface other than the reflective surface of the prism, and the bonded surface is covered with fused glass. The prism is fused to hold the prism, and an entrance window through which the light enters and an exit window through which reflected light exits are provided at predetermined positions in the case.

[0006]

Embodiment FIGS. 1 to 3 show a gasoline-alcohol mixed fuel mixture ratio sensor 10 as an embodiment of the present invention.
0 and the mixed fuel flows through the fuel supply path 20 of the engine.
0 and detects the fuel mixture ratio.

The fuel mixture ratio sensor 100 includes a sensor unit 1 and a tip end (lower end in the drawing) of the sensor unit 1 in a resin sensor body 300 whose upper part in the figure is an installation chamber 301 for a sensor circuit board. A measurement chamber housing 2 into which the measurement chamber housing 2 is fitted and forms a measurement chamber for the liquid to be measured is integrally molded by injection molding.

The sensor unit 1 includes a cylindrical metal shell 3 whose lower part is fitted into the upper part of the housing 2, which has a cylindrical shape with a bottom, and is brazed to the tip (lower end in the figure) of the metal shell 3. is fitted into a cylindrical case 41,
The prism 4 is fused with a fused glass 42. Further, a cylindrical element holder 5 holding a light emitting element and a light receiving element is accommodated within the metal shell 3.

The housing 2 is made of stainless steel and has a bottom 21 whose lower surface bulges downward in the shape of a truncated cone, and a cylindrical body 22. A fuel inlet 2 is provided at the bottom of the shell 22.
3 and the outlet 24 are opened, and the fuel pipe 201,
The tip of 202 is inserted and brazed. Moreover, the inside is a measurement chamber C, into which a mixed fuel of gasoline and alcohol flows in through the inlet 23 and flows out through the outlet 24 .

The main metal fitting 3 is made of stainless steel and consists of a small diameter lower part 32 having a lower end 31 shaped like an inner peripheral edge, and a large diameter upper part 33 having a thin upper end. A flange 34 is provided protrudingly. When the lower part 32 is fitted into the body 22 of the housing, the lower end face faces the measurement chamber C, and the upper part 33 protrudes above the housing 2;
The flange 34 abuts against the upper end surface of the barrel 22. The inner periphery is bordered by a step formed at a position corresponding to the flange 34,
The lower part has a small diameter and the upper part has a large diameter.

In this embodiment, the prism 4 is made of cylindrical optical glass, and has a stainless steel cylindrical case 41 on its outer peripheral surface except for the lower end surface 43 and the upper end surface 44, which are reflective surfaces.
is covered and fused with a fused glass 42. This fusing is performed by utilizing the difference in melting point between the fusing glass and the optical glass, and the fusing glass 42 serves as a fixing means as well as a sealing means. A flange 45 is provided around the lower end of the case 41, and the outer periphery of the flange and the lower end surface of the metal shell are fixed by brazing. Opposite axial slits are formed in the cylindrical surface of the case 41, and serve as an entrance window 46 and an exit window 47, respectively.

With this configuration, the prism 4 is located at the lower part 32 of the metal shell, and an annular space 40 is formed between the inner peripheral wall of the lower part 32 and the outer peripheral wall of the case 41. Note that the case 41 may have a structure that covers the upper end surface 44 of the prism and a portion of the lower end surface 43 that does not contribute to reflection. Further, the case 41 and the metal shell 3 may be integrally molded, or may be fixed by screwing or other fastening means. Furthermore, if the prism has another shape such as a truncated cone shape, a hemispherical shape, or a prismatic shape, the shape of the case is also formed to match the shape of the prism.

In this embodiment, the element holder 5 has two upper and lower parts.
It consists of an assembly of a divided lower holder 6 and upper holder 7. The lower holder 6 has a cylindrical portion 61 inserted into the annular space 40, and a flange portion 62 extending from its upper end to the outer periphery and abutting against the step 37 of the metal shell. Cylinder part 6
In the inner wall of the case 41, grooves 63 and 64 for inserting the element board, which have an I-shaped cross section and extend in the axial direction and in the direction tangent to the cylindrical surface, are parallel to and correspond to the entrance window 46 and the exit window 47 of the case 41. It is set up as follows.

The upper holder 7 has a recess 71 on the lower surface, an O-ring groove 72 on the outer periphery of the lower end, and
A step 73 is provided around the outer periphery of the upper end. A cylindrical edge 74 protrudes from the upper surface, and the groove 63 inside this edge 74,
A predetermined number of small tapered holes 75 are opened at positions corresponding to the lead pins 64 to serve as lead pin extraction ports.

A light-emitting element 51 and a light-receiving element 52 are fixed to the grooves 63 and 64, respectively, and a ceramic strip-shaped substrate 53 on which leads of these elements are printed.
, 54 are fitted. The upper ends of these substrates 53 and 54 protrude into the recess 71, and a lead pin 55 is brazed to each of these portions. The lead pin 55 is inserted through the small hole 75 and taken out at the top, and the top surface of the small hole 75 is covered with a silicone resin. Further, the recess 71 and the small hole 75 are filled with epoxy resin.

The element holder 5 is fitted into the metal shell 3 in the assembled state, and is fixed within the metal shell 3 by caulking the upper end of the metal shell inward. In addition, a buffer material 35 consisting of an O-ring sandwiched between metal rings is interposed between the step 73 of the upper holder and the caulking part, and this cushioning material 35 is used to alleviate the impact during caulking and to absorb the difference in thermal expansion during use. It is carried out.

As shown in FIG. 2, in this mixture ratio sensor 100, light that enters the prism 4 from the light emitting element 51 through the entrance window 46 is reflected by the reflection surface 43, exits from the output window 47, and reaches the light receiving element 52. . The amount of light increases or decreases depending on the mixture ratio of gasoline and alcohol, which is the liquid to be measured, as the critical angle for total reflection on the reflective surface changes. Light receiving element 52
converts this change in light amount into an electrical signal and outputs it.

Incidentally, the entrance window 46 and the exit window 47 allow the light emitted by the light emitting element 51 to be reflected by the reflective surface 43,
Its size and position are set so that all the components received by the light receiving element 52, that is, the signal components contributing to the detection of the fuel mixture ratio, can pass through. Therefore, the surface of the prism covered with the case 41 is a part where unnecessary light for detection, such as noise components that do not contribute to detection of the mixture ratio, is irradiated, and by covering the prism surface with the case 41, the sensitivity of the sensor is improved. can.

[0019]

Effects of the Invention As explained above, in the fuel mixture ratio sensor of the present invention, the surface other than the reflective surface of the glass prism is covered with the metal case and fused with the fused glass, so that the case and the prism are bonded together. can be fused over a wide area. This prevents peeling of the fused surface and cracking of the prism even under usage conditions where vibration is applied and temperature changes are large, allowing long-term use. Furthermore, glass and metal, which have excellent corrosion resistance, are constantly in contact with gasoline and alcohol, so they have excellent durability.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view of a fuel mixture ratio sensor.

FIG. 2 is an enlarged view of the main part of FIG. 1;

FIG. 3 is a perspective view of the metal holding means.

[Explanation of symbols]

1 Sensor unit 2 Housing 3 Main metal fittings 4 Prism 41 case 42 Fused glass 43 Reflective surface 46 Entrance window 47 Exit window 100 Fuel mixture ratio sensor

Claims (1)

[Claims] 1. A glass prism having a reflective surface in contact with a liquid to be measured in which two or more types of translucent liquids are mixed;
In an optical liquid mixture ratio sensor that combines a light-emitting element that irradiates light to the prism and a light-receiving element that detects light reflected by the prism, a metal case is covered with a surface other than the reflective surface of the prism and bonded. A liquid mixture ratio sensor characterized in that a prism is held by fusing a surface with a fusing glass, and an entrance window through which the light enters and an exit window through which reflected light exits are provided at predetermined positions of the case.