JPS6318247A - Fuel component detector - Google Patents

Abstract

PURPOSE:To enable the detection of fuel components accurately regardless of temperature changes, by providing a light emitting section at one end of a light guide contacting a fuel and a light receiving section at the other end thereof. CONSTITUTION:A light guide 3 comprises a first member 6 and a second member 7 linked thereto and the refractive index of the member 7 changes in such a manner as to be larger in the difference from that of the member 6 with a rise in the temperature. The member 7 is surrounded by a light shielding member 8 so that light is reflected effectively on the interface with the member 6. Both ends of the light guide 3 sticks out of a fuel cell 1 and a light emitting section 4 is provided at one end thereof 3 and a light receiving section 5 at the other end thereof. Light projected to one end of the light guide 3 from a light emitting section 4 travels through the light guide 3 while light is leaked at a fixed rate determined by the refractive index of a fuel 2 and comes out to the other end thereof to be received by the light receiving section 5. Furthermore, the quantity of light emitted from the light emitting section 4 and the quantity of light received by the light receiving section 5 are inputted into a component detector section 9 and components of the fuel is detected. This enables accurate detection of the fuel regardless of changes in the temperature.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an improvement of a fuel component detection device, and more particularly, to a fuel component detection device that can accurately detect fuel components even when a temperature changes. This is used, for example, in the field of detecting components such as automobile fuel.

[Prior art]

In Japan, unleaded premium and regular are used as automatic Ichikawa fuel, but in Colonopa, gasoline mixed with a small amount of alcohol component such as methanol or ethanol is used in practical use. therefore,
In the near future, it is certain that methanol, which is considered the most promising alternative fuel to petroleum in Japan, will be mixed with gasoline and diesel oil as automobile fuel.

The actual situation of such diversification of fuel components varies depending on the region, and automobile manufacturers are dealing with this by adjusting engine ignition timing and other factors depending on the destination. However, in the current situation where the above-mentioned diversification is progressing even in the same region, it may not be possible to make sufficient adjustments to the engine, resulting in various troubles. Therefore, it is essential to develop a wide-range fuel engine that can handle the diversification of fuel components, and along with this, there is a need to develop a compact sensor that can detect fuel components.

Under these circumstances, a fuel component detection device that utilizes the change in the refractive index of light depending on the components of gasoline fuel was proposed at the 4th International Alcohol Fuel Technology Symposium (
IV International Symposia
um Alcohol Fuel Technology
y, Host country: Brazil, Date: October 5, 1980
- 8th) Minutes Volume 11 (Vol. I) No. 8 2.4
It was announced on 9'l.

This fuel component detection W position consists of a transparent light guide immersed in fuel, a light emitting part that enters light into one end of the light guide, and a light receiving part that receives light emitted from the other end of the light guide. The components of the fuel are detected based on the amount of light received. In other words, the light emitted from the light emitting section is repeatedly reflected and refracted at the interface between the light guide and the fuel before reaching the light receiving section. , which detects the amount of components in the fuel that contribute to changes in the refractive index.

[Problem that the invention seeks to solve]

In conventional detection devices such as those described above, while the refractive index of the fuel itself changes with temperature, the refractive index of the light guide also changes, and as the temperature rises, the ratio of the refractive index of the fuel to the refractive index of the light guide decreases. . Therefore, as the temperature rises, it becomes difficult for light to leak from the light guide path, and the amount of light received increases, causing a so-called temperature drift.

By the way, in order to detect fuel components, it is necessary to detect the refractive index of the fuel with high accuracy, so it is necessary to increase the sensitivity of the light receiving section formed by a photoelectric conversion element or the like. However, increasing the detection sensitivity of the light receiving section increases the temperature drift described above, which affects detection accuracy. Therefore, conventionally, a temperature sensing element such as a thermistor was used to detect the temperature of the light receiving part.
Temperature drift was corrected using a microcomputer. However, placing a semiconductor such as a thermistor in close proximity to or in contact with flammable fuel is not appropriate in terms of explosion protection or corrosion resistance, and the device itself becomes complicated, large, and expensive. There was point f.

The present invention was made in consideration of such circumstances, and
It is an object of the present invention to provide a fuel component detection device that can accurately detect fuel components even when the temperature changes.

[Means for solving problems]

Means of the present invention for achieving the above object is a fuel component detection device in which a light guide in contact with fuel is provided with a light emitting part at one end and a light receiving part at the other end, the light guide being a first member. and a second member connected thereto, the refractive index of the second member changing as the temperature rises such that the difference from the refractive index of the first member increases.

[For production]

The amount of light that enters the light guide from the light emitting portion leaks is reduced due to a decrease in the refractive index ratio of the fuel to the first member due to the rise in temperature, and the amount of light in the light guide increases. On the other hand, as the temperature rises, the refractive index of the second member changes so that the difference with the first member becomes larger, and the reflectance at the interface increases.

Therefore, the increase in the amount of light due to the rise in temperature is reflected at the interface between the first member and the second member, preventing it from reaching the light receiving section, and temperature correction of the amount of received light is automatically performed.

〔Effect of the invention〕

The fuel component detection device of the present invention is a fuel component detection device in which a light guide path in contact with fuel is provided with a light emitting section at one end and a light receiving section at the other end, and the light guide path is connected to a first member. The refractive index of the second member changes as the temperature rises so that the difference from the refractive index of the first member increases. is reflected at the interface between the first member and the second member, and the amount of received light is corrected. Therefore, regardless of temperature changes, the refractive index of the fuel can be accurately determined.
Fuel components can be detected accurately.

〔Example〕 The present invention will be described in detail below based on examples thereof.

The fuel component detection device of this embodiment is installed in the fuel piping of a so-called wide range fuel engine, and accurately detects fuel components regardless of temperature changes. This allows the actuator to be automatically adjusted. The main body of the device is the first
As shown in the figure, a light guide path 3 is immersed in fuel 2 branched from a fuel pipe (not shown) and introduced into a fuel cell 1, and a light emitting section 4 is provided at one end of the light guide path 3, and a light receiving section 5 is provided at the other end.

The light guide path 3 consists of a first member 6 and a second member 7 connected thereto, and the refractive index of the second member 7 is such that the difference from the refractive index of the first member 6 increases as the temperature rises. Changes to

The light guide path 3 is formed in a U-shaped rod-like body, and from one end where the light emitting part 4 is provided, most of it including the curved part consists of a first member 6 for measuring the amount of light, and the other end continues from this. A small portion leading to the second member 7 is used for temperature correction. The second member 7 is surrounded by a light-shielding member 8, so that light is effectively reflected at the interface with the first member 6. Both ends of the light guide path 3 protrude outside the fuel cell 1, and a light emitting section 5t serving as a light source is provided at one end, and a light receiving section 5 made of, for example, a photoelectric conversion element is provided at the other end.

Then, the light projected from the light emitting part 4 to one end of the light guide path 3 travels inside the light guide part 3, and a certain proportion of light determined by the refractive index of the fuel 2 is leaked to the other end +! '! The light is emitted to the light receiving section 5 and is received by the light receiving section 5. The amount of light emitted by the light emitting section 4 and the amount of light received by the light receiving section 5 are input manually to a component detecting section 9, which includes a microcomputer or the like, and the fuel components are detected.

As is well known, aromatic substances such as benzene with a high octane number have a high refractive index, while paraffin-based substances with a low octane number have a low refractive index. In addition, it has a lower refractive index than alcohol components such as methanol and ethanol. This refractive index can be detected based on the ratio of the amount of light received by the light receiving section 5 to the amount of light emitted by the light emitting section 4. Therefore, based on the detected refractive index, the octane number of ordinary gasoline can be determined, and the alcohol content of gasoline mixed with alcohol can be determined. The reason why the light guide path 3 is formed in a U-shape is to allow as much light as possible (by leaking it into the fuel 2, the light receiving gIS5 receives only the amount of light that contributes to the detection of fuel components, improving detection accuracy and This is to make the device compact for mounting.

By the way, as already mentioned, the refractive index of the fuel 2 changes depending on the temperature, so in order to detect the refractive index with higher accuracy, it is necessary to perform appropriate temperature correction. Therefore, in this embodiment, the first member 6 is made of quartz glass, and the second member 7 is made of calcite CaC, which has a higher refractive index than quartz glass.
It is made of O3, and by reflecting a part of the light at the interface between the two members, the amount of received light is reduced and temperature correction is performed.

In addition, the refractive index n of fuel tI2 at room temperature is 1.42 to 1
．． 43 Te, rate of change with respect to temperature dn /dT = -2~
-3X 10-', refractive index of silica glass n+ = 1.
456, the rate of change with temperature dn+ / dT-3X
10-6, the refractive index of calcite n2 = 1.654, and the temperature change rate dn2/dT = 5 x 10-6.

Also, the reflectance R at the boundary surface is (n+ -nz / n+
+r12)2. Therefore, as shown in FIG. 2, the refractive index n2 of the second member 7 changes as the temperature increases.
The difference between the refractive index of the first member 6, that is, the reflectance R changes to become larger.

With this configuration, as the temperature rises, the ratio of the refractive index n of the fuel 2 to the refractive index of the first member 6 decreases, the amount of light leakage decreases, and the amount of light inside the first member 6 increases. do. By reflecting this increased amount at the boundary surface, it is possible to prevent it from reaching the light receiving section 5. In other words, a temperature drift in the refractive index due to an increase in ambient temperature is corrected by automatically increasing the amount of reflected light by increasing the reflectance R.

In addition, apart from the above, when employing the second member 7 having a smaller refractive index than the quartz glass used for the first member 6, for example, fluorite CaF2 (refractive index n3 = 1.432° temperature change rate dn3/dT -5X 1O-5), as shown in FIG.
changes so that it becomes larger. Therefore, similarly to the above, temperature drift can be corrected and fuel components can be detected with high accuracy. In the above embodiment, the light is guided from the first member 6 to the second member 7, but the light may be received by taking the opposite path.

As described above, according to the present arrangement, temperature drift in the amount of light can be accurately corrected in automatic fishing with a compact device without providing a correction circuit using a temperature detection element or the like. Therefore, in particular, it is possible to detect the mixing ratio of high octane gasoline and regular gasoline, which has not always been easy in the past, and the practical effects are great. Although the light guide path 3 is formed in a U-shape in this embodiment, the present invention does not specify the shape. Furthermore, it is not necessarily necessary to use a microcomputer in the component detection section 9 (
It is also possible to amplify the output of the light receiving section 5 and directly drive various actuators.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram showing the general configuration of an embodiment of the present invention, and FIG.
The figure is a graph showing temperature changes in the refractive index of the first member and the second member, and FIG. 3 is a graph showing the temperature change in the refractive index of the first member and the second member in different embodiments. 2-fuel, 3-light guide path, 4-light emitting section, 5-light receiving section, 6.
-・First member, 7-Second member.

Claims (1)

[Claims] (1) A fuel component detection device including a light-emitting section at one end of a light guide in contact with fuel and a light-receiving section at the other end, the light guide comprising a first member and a second member connected to the first member. . A fuel component detection device, wherein the refractive index of the second member changes as the temperature increases so that the difference from the refractive index of the first member increases.