JPH0247487Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a photoelectric conversion sensor for detecting the gasoline-alcohol mixture ratio of a gasoline-alcohol mixture as a fuel for an internal combustion engine.

[Conventional technology]

Petroleum resources, which are now indispensable to daily life for the transportation of people and goods and as raw materials for industrial products, are destined to continue to be depleted in the future. As a countermeasure, there is a plan to reduce oil consumption as much as possible by manufacturing alcohol from plants, natural gas, coal, etc. that can be reproduced over a very short period of time, and mixing it with gasoline. It is being carried out in various places.

[Problems to be solved by the invention] In the case of internal combustion engines, especially automobile engines, in connection with the above-mentioned problems, it is necessary to increase the combustion efficiency as much as possible, and to minimize the adverse effects of harmful combustion exhaust gases on the human body. In order to achieve this, it is necessary to particularly strictly control the air-to-fuel ratio of the air-fuel mixture supplied into the engine cylinder and the ignition timing. Naturally, these control conditions must be changed each time the type of fuel differs. In the case of gasoline-alcohol mixed fuel, it is desirable to have a system that allows mixed use of the mixed fuel and gasoline, considering ease of use in the market.

This invention is a gasoline-to-alcohol device with improved measurement accuracy that can be incorporated into the fuel supply system of an internal combustion engine to continuously measure the gasoline-alcohol mixture ratio and supply feedback control information to the automatic combustion control device of the internal combustion engine. The purpose is to provide a mixing ratio sensor.

[Means for solving problems]

Gasoline of this invention to achieve the above purpose
The alcohol mixture ratio sensor consists of a rod-shaped translucent body whose both ends are supported by gripping members and whose outer peripheral surface is in contact with the gasoline-alcohol mixture, with a light-emitting element on one end face and a light-emitting element on the other end face. In the gasoline-alcohol mixture ratio sensor that is installed with the center lines of each of these three light flux passing directions aligned, the length and radius of the rod-shaped transparent body and the method of attaching the gripping member are different from those of the rod-shaped transparent body. is incident on one end face of the gas, and the mixture ratio of gasoline to alcohol is
A configuration was adopted in which all of the light irradiated with a critical angle at the contact interface with the mixed liquid of 100:0 to 0:100 was totally reflected only once and then reached the other end face.

[Effects of action and design]

The mixture ratio sensor according to the present invention having the above-mentioned configuration is configured such that the length and radius of the rod-shaped transparent body and the attachment method of the gripping member of the rod-shaped transparent body are inputted to one end surface of the rod-shaped transparent body, and gasoline to alcohol The mixing ratio of
By setting it so that all of the light irradiated with a critical angle at the contact interface with the mixed liquid of 100:0 to 0:100 is totally reflected only once, and then reaches the other end surface, a rod-shaped Compared to a rod-shaped transparent body whose shape and dimensions are such that light that enters the transparent body from one end surface of the transparent body undergoes total reflection two or more times before reaching the other end surface, the light travels through the transparent body. It is possible to sufficiently reduce the degree to which light is dissipated from the outer peripheral surface to the outside world or attenuated due to the extension of the optical path length.

As a result of experiments, it has been found that as the number of total reflections of light passing through the light-transmitting body increases, the tendency for the output voltage of the light-emitting element to change linearly with respect to changes in the gasoline-alcohol mixture ratio is lost. The sensor of the present invention, in which total reflection of light occurs only once within the body, maintains a sufficiently good linear relationship between the gasoline-alcohol mixture ratio and the electrical output, increasing the measurement accuracy of the sensor. can.

Such a measure to improve the measurement accuracy of the sensor does not require any special additional expenditure in manufacturing the sensor.

〔Example〕

The specific configuration of the present invention will be described below based on the embodiments shown in the accompanying drawings.

FIG. 1 is a side sectional view of an embodiment of the sensor according to the present invention, in which both ends of a rod-shaped transparent body 1 made of glass have inner cavities of different diameters made of metal, synthetic resin, etc., and have a short cylindrical shape. The holding member 4 or 5 is fitted into the inner cavity on one end side of the holding member 4 or 5. In the inner space on the other end side of the gripping member 4, a light emitting diode 2 as a light emitting element has its light emitting part facing one end surface 1a of the rod-shaped transparent body 1 so that the center line of each light beam traveling direction is They are fitted to match. 2a and 2b are input terminals of diode 2. Further, in the inner space on the other end side of the gripping member 5, a photodiode 3 as a light emitting element has its light-receiving surface facing the other end surface 1b of the rod-shaped transparent body 1, so that the center lines of the respective light flux traveling directions coincide with each other. It is fitted in such a way that 3a and 3b are photodiodes 3
This is the output terminal of

A cylindrical casing 6 is fitted between the gripping members 4 and 5 so as to span the outer peripheral surfaces of these two members, and the rod-shaped transparent body 1 and the cylindrical casing 6
The cylindrical closed space between the two serves as a mixed liquid reservoir 7 for bringing the gasoline-alcohol mixed liquid whose mixing ratio is to be measured into contact with the rod-shaped transparent body 1.
The cylindrical casing 6 is provided with an inlet joint 6a and an outlet joint 6b for the mixed liquid to be measured. Furthermore, a groove 8a for fitting an O-ring 8 is provided on the inner wall surface of both gripping members 4 and 5 to prevent the mixed liquid from leaking to the outside from the contact gap between these members and the rod-shaped transparent body 1. be.

FIG. 3 is a diagram of an operation control system for an automobile engine incorporating an electronically controlled fuel injection device, in which 40 is an engine cylinder, 50 is an engine key switch, 51 is a control circuit, 55 is an on-vehicle battery power source, and 20 is an engine key switch. The fuel tank A is a gasoline-alcohol mixture ratio sensor according to the present invention.

The main components of the fuel system are 21 a sulfur pump, 23 a pressure regulator, 24 an injector, 26 a cold start injector, 25 an ignition coil, 30 an air cleaner, and 31 an air valve. , 32 is an air flow meter, 33 is a slot valve, 34 is a throttle position sensor, 35 is an intake pipe, and 36 is an exhaust pipe. Further, 52 is an oxygen sensor, and 53 is an engine cooling water temperature sensor.

Next, the operation of the above embodiment sensor A will be explained with reference to FIGS. 1 to 3. By setting the engine key switch 50 to the start position, the engine is started and operating power is supplied to the control circuit 51. The fuel stored in the fuel tank 20 as a mixture of gasoline and alcohol (generally methanol 5) in an arbitrary ratio is supplied to the injector 24 along the fuel pipe 22 by the action of the fuel pump 21. Ru.
The injector 24 injects the fuel mixture into the intake pipe 35 in an amount most suitable for the engine operating conditions at the time according to instructions from the control circuit 51.

The mixture ratio sensor A is interposed in the middle of the fuel pipe 22, and its mixed liquid inlet joint 6a and outlet joint 6b are connected to the pipe 22, respectively. Since a constant voltage current is continuously applied to the light-emitting element 2 from the control circuit 51, the light emitted from the light-emitting element (light-emitting diode) 2 passes through one side of the rod-shaped transparent body placed opposite to the light-emitting surface of the element. It penetrates into the transparent body 1 from the end face. As shown in FIG. 1, the transparent body 1 is housed in a cylindrical casing 6 filled with a fuel mixture C, and the outer circumferential surface is in contact with the mixture, so that the mixture C is in contact with the mixture. Light that enters from the end surface 1a with an angle of incidence smaller than the critical angle of the transparent body 1 at the contact interface with C is totally reflected at the contact interface and reaches the other end surface 1b of the transparent body 1. Since the light-receiving surface of the light-emitting element (photodiode) 3 placed opposite to the end face is irradiated,
An output proportional to the amount of irradiated light is generated between the output terminals 3a and 3b of the element. On the other hand, light that enters at an incident angle larger than the above-mentioned critical angle escapes from the transparent body 1 after reaching the outer circumferential surface of the transparent body 1, so that it outputs no output to the light emitting element 3. It does not involve anything that causes it.

The critical angle of the transparent body 1 at the contact interface with the mixed liquid C naturally changes depending on the mixing ratio of gasoline and alcohol, which are the constituent components of the mixed liquid.
Of the light emitted from the light emitting element 2, the proportion of the amount of light that undergoes only one total reflection within the light transmitting body 1 and reaches the light emitting surface of the light emitting element 3 changes as the mixture ratio of gasoline to alcohol changes. become. Therefore, by experimentally determining the relationship data between the output of the light-emitting element 3 and the gasoline-alcohol mixture ratio in advance, it is possible to calculate the output of the light-emitting element as a value converted to the gasoline-alcohol mixture ratio by using an electronic circuit. It can be easily used and functions as a mixing ratio sensor.

By the way, regarding the mixture ratio sensor A having the above-described structure, the inventors of the present application mainly changed the dimensions of the rod-shaped transparent body 1 and the method of attaching it variously, and the output voltage of the light emitting element 3 and the difference between gasoline and alcohol. We conducted a series of experiments to see how the shape of the correlation graph changes with the mixing ratio of the mixed liquid, and found that when the diameter of the rod-shaped transparent body 1 was kept constant and its length was changed, It was confirmed that the graph draws a nearly straight line in a relatively short length range, but as the length increases beyond that, the linearity of the graph gradually disappears. The graph in FIG. 4 summarizes the results of this experiment. graph
Graph (a) is for a sensor using a relatively short transparent body 1, graph (b) is for a sensor that incorporates a longer transparent body 1, and graph (c) is for a sensor that uses a longer transparent body 1. Each of these is drawn for a sensor using No. 1.

It goes without saying that the closer the correlation graph between the output of the light emitting element 3 and the mixture ratio of gasoline to alcohol mixture is to a straight line, the higher the measurement accuracy as a mixture ratio sensor. There is a need to create sensors with such characteristics. The main reason for the gradual loss of linearity as shown in graphs (b) to (c) is that as the length of the transparent body 1 increases, the number of reflections of light within the transparent body increases and the optical path length also increases. It can be interpreted that this is because the degree of attenuation of light increases.

Based on these experimental results, it was concluded that measurement accuracy can be improved by maintaining a linear correlation between the output voltage of the light emitting element 3 and the gasoline-alcohol mixture ratio of the mixed liquid to be measured. In order to obtain a sensor with a high mixing ratio, the light should be incident on one end surface of the rod-shaped transparent body 1, and the mixing ratio of gasoline to alcohol should be
100: The length and radius of the rod-shaped transparent body 1 are set so that all of the light incident at the critical angle at the contact interface with the mixed liquid of 0 to 0 to 100 reaches the other end surface after being totally reflected only once. What is necessary is to set the method of attachment to the gripping member.

Therefore, the length of the rod-shaped transparent body 1 is L, the radius is r,
The length of the gripping member 4 in the light traveling direction is d, the length L is the value obtained by subtracting the length of the gripping member 5 attached to the other end surface in the light traveling direction D, and light is transmitted from the light emitting surface of the light emitting element. Let n be the distance to one end of the body,
The critical angle of the transparent material at the interface in contact with 100% alcohol is θa, the incident angle of light that produces this critical angle is φa, the critical angle of the transparent material at the interface in contact with 100% gasoline is θg, and the angle of incidence of light that produces this critical angle is θg. Letting the angle of incidence of the light to be illuminated be φg, the conditions for the propagation of light within the rod-shaped transparent body 1 as described above are satisfied.
The values of the length L and radius r of the rod-shaped transparent body 1 and the length d of the gripping member 4 were calculated, and these values were calculated so that the following inequalities (1) to (3) could be satisfied. It turns out that it is sufficient to set the value of (see Figure 2).

L＜(3r−d tan φa)tan θa……(1) D＞(r−d tan φg)tan θg……(2) d＜(r−d tan φa)tan θa……(3) Above The incident angle φ and critical angle θ are the values actually measured for methanol and commercially available regular gasoline at a temperature of 20°C: φa = 39.4°, θa = 64.4°, φg
= 20.9° and θg = 75.9°, so for example, the transparent body 1
When the radius r of is set to 2.0 (mm) and the distance from the light emitting surface of the light emitting element 2 to the one end surface 1a of the transparent body is set to 1.2, L<10.6, D> from equations (1) to (3). 5.8, d<
The value of 2.1mm can be found.

[Brief explanation of the drawing]

Fig. 1 is a side sectional view of an embodiment of the sensor according to the present invention, and Fig. 2 is a calculation formula for determining the length and radius of the rod-shaped transparent body and the mounting method necessary to achieve the object of the present invention. Figure 3 is a system diagram of an electronically controlled fuel injection device for an automobile engine incorporating the sensor of the present invention.
Figure 4 shows the output voltage of the sensor light emitting element versus gasoline.
FIG. 3 is a diagram showing how the shape of a correlation graph of alcohol mixing ratios is influenced by the dimensions of a rod-shaped transparent body. In the figure, A...Mixing ratio sensor, 1... Rod-shaped transparent body, 2... Light emitting element, 3... Light receiving element, 4, 5...
... Gripping member, 6... Cylindrical casing, C... Mixed liquid, L... Length of rod-shaped transparent body, d... Length of grasping member on one end surface side.

Claims (1)

[Claims for Utility Model Registration] 1. A rod-shaped transparent body whose both ends are supported by gripping members and whose outer peripheral surface is in contact with a gasoline-alcohol mixture, with a light-emitting element on one end face and a light-emitting element on the other end face. In the gasoline-alcohol mixture ratio sensor in which the light-receiving elements are mounted so that the center lines of each of these three light flux passing directions coincide with each other, the length and radius of the rod-shaped transparent body and the method of attaching the gripping member are All of the light that is incident on one end face of the translucent body and irradiated at a critical angle to the contact interface with the mixed liquid with a mixture ratio of gasoline and alcohol of 100:0 to 0:100 is totally reflected only once. The gasoline-alcohol mixture ratio sensor is characterized in that the sensor is configured to reach the other end face. 2. The length of the rod-shaped transparent body is L, the radius is r, the length in the light traveling direction of the gripping member attached to the one end surface is d, and the gripping member attached to the other end surface from the length L The value obtained by subtracting the length of the member in the light traveling direction is D, the distance from the light emitting surface of the light emitting element to the one end face is n, and the critical angle of the rod-shaped transparent body at the interface in contact with 100% alcohol is θa. , the incident angle of the light that produces this critical angle is φa, the incident angle of the rod-shaped light guide at the interface in contact with 100% gasoline is θq, and the incident angle of the light that produces this critical angle is φg, then the above L , D, and n so that the following inequalities L<(3r−d tan φa)tan θa D>(r−d tan φg)tan θg d<(r−d tan φa)tan θa hold, respectively. The gasoline-alcohol mixture ratio sensor according to claim 1 of the utility model registration claim, characterized in that: