JPS62127646A - Sensor for gasoline-alcohol mixture ratio - Google Patents

Abstract

PURPOSE:To prevent the titled sensor from being affected by environmental temp. by attaching a light receiving element for temp. compensation for which part of the light radiated from a light emitting element is used as a light source into the case of the light emitting element and controlling the power feed quantity to the light emitting element in such a manner that the specified output of the light receiving element for temp. compensation is maintained. CONSTITUTION:The light receiving element 4 for temp. compensation is attached at the point in the case of the light emitting element where the light receiving element can receive the irradiation of the light emitted the body of the element 2, i.e., a photodi ode chip 2. A circuit for controlling the power feed quantity to the light emitting element is provided to invariably maintain the output of the light receiving element 4 by suppressing the floating of the output of the light receiving element when the output of said element is going to float according to the fluctuation of the environmen tal temp. The deterioration in the accuracy of the measurement with the sensor A arising from the influence of the ambient environmental temp. on the electrical characteristics of the light emitting element 2, the light receiving element 3 and the light receiving element 4 for temp. compensation is thereby averted. The elements 2-4 having the approximate temp. characteristics as far as possible are used.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] 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 moving vehicles that transport people and goods, and as raw materials for industrial products, are definitely destined to run out in the future. . As a countermeasure, there are plans in various places to manufacture alcohol from plants, coal, natural gas, etc. that can be reproduced over a very short period of time, and to mix it with gasoline to reduce oil consumption as much as possible. It is being advanced.

[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 combustion efficiency as much as possible, and to reduce the adverse effects of harmful combustion exhaust gases on the human body as much as possible. In order to reduce this, it is necessary to particularly strictly control the air-to-fuel ratio of the mixture supplied into the engine cylinder and the ignition timing. Naturally, these control conditions must be changed for each different type of fuel. In the case of gasoline-alcohol mixed fuel, considering ease of use in the market, it is desirable to have a system that can be used in combination with gasoline.

The present invention can be incorporated into the fuel supply system of an internal combustion engine to
Gasoline with improved measurement accuracy and extremely little influence by environmental temperature in the measurement area, in order to continuously measure the alcohol mixture ratio and provide feedback control information to the automatic combustion control device of the internal combustion engine. - To provide an alcohol mixture ratio sensor.

[Means for Solving the Problems] In order to achieve the above object, the gasoline-alcohol mixture ratio sensor according to the present invention includes a rod-shaped transparent body whose outer circumferential surface is in contact with the gasoline and alcohol mixture. A sensor that detects the mixing ratio by placing a light receiving element on the other end of a light emitting element and measuring the amount of light that is totally reflected and passed through the rod-shaped transparent body, which increases or decreases as the composition of the mixed liquid changes. A temperature-compensating light-receiving element for correcting the temperature characteristics of the sensor is installed in the case of the light-emitting element, and the temperature-compensating light-receiving element uses part of the emitted light of the light-emitting element as a light source, and the output of the temperature-compensating light-receiving element is In order to maintain a constant value, a configuration was adopted in which a power supply control circuit was provided to control the power supply to the light receiving element.

[Operations and Effects of the Invention] The mixture ratio sensor having the above-mentioned configuration has a critical part of the light emitted from the light emitting element to which a constant current is continuously supplied to the interface between the transparent body and the mixed liquid. Light incident on one end face of a translucent body with an incident angle that is larger than the angle at which it is irradiated is reflected only once (total reflection occurs, reaches the other end face, and transfers light energy to the photodetector). to produce an output voltage.

Since the above critical angle differs depending on the mixing ratio of gasoline and alcohol, the amount of light that is totally reflected and passes through the transparent body also changes, and the output voltage of the light receiving element also changes accordingly. By checking this output voltage, it functions as a mixing ratio sensor.

The critical angle described above varies depending on the environmental temperature in which the sensor is placed, and the photoelectric conversion characteristics of the light emitting element and the light receiving element are also influenced by the environmental temperature.

Therefore, if part of the light emitted from the light-emitting element is irradiated onto the temperature-compensating light-receiving element, and the power supply control circuit to the light-emitting element is activated so that the output is kept constant regardless of the temperature change, The light emitting element is supplied with current that is increased or decreased in response to changes in the environmental temperature, so to speak, with temperature correction performed, and the disadvantage that the measurement accuracy of the sensor is affected by the environmental temperature is almost eliminated.

Since the temperature-compensating light-receiving element is pre-integrated into the case of the light-emitting element, the assembly structure of the sensor can be made extremely simple, and the external shape can also be made compact.

Furthermore, since the light emitted from the light emitting element has directionality, if the light is emitted from the light emitting element and then passes through a rod-shaped light transmitting element, the light receiving element for temperature compensation is irradiated with the light.
During this process of light passage, the temperature compensation function becomes unstable due to the influence of changes in the composition of the liquid mixture and the environmental temperature, but the sensor of the present invention does not suffer from such problems.

[Example] A specific configuration of the present invention will be described below based on an example shown in the accompanying drawings.

Figures 1 to 4 all show one embodiment, with Figure 1 depicting a side cross section of a gasoline-alcohol mixture ratio sensor, and Figure 2 depicting a side cross section of a light emitting element. Reference numeral 5 denotes a casing of the mixture ratio sensor A, which is made of metal or engineering plastic. A rod-shaped light-transmitting body 1 made of optical glass has its both ends fitted and fixed in holes that are bored through both cylindrical end faces of a casing 5 in the form of a cylindrical container. An internal space 6 of the casing 5 forms a passageway for the mixed liquid to be measured, and an inlet joint 7 and an outlet joint 8 for the mixed liquid to be measured are attached to the peripheral wall of the casing 5.

A light-emitting element 2 such as a light-emitting diode and a light-receiving element 3 such as a photodiode are mounted in a casing 5 such that their light-emitting and light-receiving surfaces are opposed to one end surface 1a and the other end surface 1b of the rod-shaped transparent body 1, respectively. is attached to the wall.

2a is the input terminal of the light emitting diode 2, 3a is the light receiving element 3
This is the output terminal of 9 is an O-ring for liquid-tightly sealing the contact surface between both ends of the rod-shaped transparent body 1 and the casing 5;
5a is an annular groove provided in the casing 5 to fit this O-ring.

As shown in FIG. 2, the light emitting element 2 has a structure in which a photodiode chip 2A, which forms the main body of the light emitting element 2, is housed in the center of a case made of a joined body of a lid part 10 and a bottom plate part 11. A temperature-compensating light-receiving element 4 is assembled near the inner circumferential surface of the case, using the board 1 to the diode chip 2A as light sources. 13 is a base body for mounting these two elements, 14 is a fixture for the light receiving element 4, 12 is a window glass for diffusing the light emitted from the photodiode chip 2A toward the outside of the case, and 4a is a This is an output terminal of the light receiving element 4.

FIG. 4 is a diagram of an operation control system for an automobile engine incorporating an electronically controlled fuel injection device using a gasoline-to-alcohol mixture ratio sensor according to the present invention, in which 37 is an engine cylinder, 50 is an engine key switch, 51
55 is a control circuit, 55 is an on-vehicle battery charge, 20 is a fuel tank, A is a gasoline-alcohol mixture ratio sensor according to the present invention, and 54 is a power supply control circuit.

21 is a fuel pump as the main components of the combustion system;
3 is a pressure regulator, 24 is an injector, 2
6 is a cold start injector, 25 is an ignition coil, 30 is an air cleaner, 31 is an air valve, 32 is an air flow meter, 33 is a throttle 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 in Figs. 1 to 4.
This will be explained with reference to the figures. engine key switch 5
By setting 0 to the start position, the engine is started and operating power is supplied to the control circuit 51. Fuel, which is a mixture of gasoline and alcohol (generally methanol) in an arbitrary ratio, stored in the fuel tank 2o is supplied to the injector 24 along the fuel pipe 22 by the action of the fuel pump 21. 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 7 and outlet joint 8 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 emitting element (light emitting diode) 2
The light emitted from the element enters the light transmitting body 1 from one end surface 1a of the rod-shaped light transmitting body 1, which is placed opposite to the light emitting surface of the element.

As shown in FIG. 1, the transparent body 1 is housed in a cylindrical casing 5 filled with a fuel mixture, and its outer peripheral surface is in contact with the mixture, so there is no contact with the mixture. The light entering the contact interface from one end surface 1a is totally reflected at the contact interface and reaches the other end surface 1b of the light transmitting material 1. Since the light reaches the end face 1b and irradiates the light receiving surface of the light receiving element (photodiode) 3 placed oppositely, an output proportional to the amount of irradiated light is generated at the output terminal of the element.

On the other hand, light that enters at an incident angle larger than the critical angle mentioned above reaches the outer circumferential surface of the light-transmitting body 1 and then escapes from the light-transmitting body 1, causing an output to the light-receiving element 3. is not involved at all.

The critical angle of the transparent body 1 at the contact interface with the mixed liquid naturally changes depending on the mixing ratio of gasoline and alcohol, which are the constituent components of the mixed liquid. The proportion of the amount of light that is totally reflected within the body 1 and reaches the light-receiving surface of the light-receiving element 3 changes as the gasoline-alcohol mixing ratio changes. Therefore, by experimentally determining the relational data between the output of the light receiving element 3 and the gasoline-alcohol mixing ratio, it is possible to calculate the output of the light receiving element 3 as a value converted to the gasoline-alcohol mixing ratio using an electronic circuit. This can be easily done using the , and functions as a mixture ratio sensor.

By the way, the light emitting element 2 which is a necessary component of the mixture ratio sensor
The photoelectric conversion characteristics of the light-receiving element 3 change with fluctuations in the environmental temperature in which the sensor is placed, and the critical angle of the transparent body 1 at the contact interface with the mixed liquid also changes as the temperature rises and falls. changes, so unless some kind of temperature compensation means is taken, it is not possible to expect sufficient measurement accuracy from the mixture ratio sensor.

Therefore, in the embodiment sensor A according to the present invention, the photodiode chip 2A which is the main body of the element 20 inside the case of the light emitting element 2 is
A temperature-compensating light-receiving element 4 is installed at a location where it can be irradiated with light emitted from the pixel, and the output level of this light-receiving element 4 fluctuates as the environmental temperature changes due to the temperature characteristics of these pixel elements. , adopted a method of using the output information of sensor A as an index for adding temperature correction.

One of the specific measures to correct the temperature of the sensor A using the output of the temperature compensation light receiving element 4 is to
If a circuit is provided to control the amount of power supplied to the light emitting element 2 in order to suppress this floating and keep the output of the light receiving element 4 unchanged, as a result, the temperature of the light emitting element 2, the light receiving element 3, and the It is possible to avoid a decrease in the measurement accuracy of the sensor A due to the fact that the electrical characteristics of the compensation light-receiving element 4 are affected by the surrounding environmental temperature. Of course, it is necessary to select and use these 2 to 4 elements whose temperature characteristics are as similar as possible.

FIG. 3 is an illustrative diagram of a power supply control circuit to the light emitting element 2, in which 2 is the light emitting element, 4 is a temperature compensation light receiving element, 60 is an operational amplifier, and 61 is the aforementioned fuel injection device. )l device control circuit 51
This is the input terminal from.

[Brief explanation of drawings]

FIG. 1 is a side sectional view of a first embodiment sensor according to the present invention, FIG. 2 is a side sectional view of a light emitting element incorporated in the sensor of FIG. 1, and FIG. FIG. 4 is an exemplary diagram of a power supply control circuit for a light emitting element, and is a diagram of an operation control system of an automobile engine incorporating an electronically controlled fuel injection device using the gasoline-alcohol mixture ratio sensor according to the present invention. In the figure 1... Rod-shaped transparent body 2... Light emitting element 2A.
...Light-emitting diode body 3...Light receiving element 4...
Temperature compensation light receiving element 5...Sensor casing 6.
...Mixed liquid passage to be measured 10.11... Case of light emitting element A... Mixture ratio sensor Fig. 1 3a Fig. 2

Claims (1)

[Claims] 1) A rod-shaped transparent body whose outer peripheral surface is in contact with a gasoline-alcohol mixture is provided with a light emitting element on one end face and a light receiving element on the other end face, and a light emitting element is placed oppositely on the other end face, and as the composition of the mixture changes, increases and decreases,
In the sensor that detects the mixing ratio by measuring the amount of light that is totally reflected and passed through the rod-shaped light-transmitting body, the light-emitting element is provided within a case of the light-emitting element, and a part of the light emitted from the light-emitting element is used as a light source. In addition to installing a temperature compensation light receiving element for correcting the temperature characteristics of the sensor, so that the output of the temperature compensation light receiving element is kept constant,
A gasoline-alcohol mixture ratio sensor comprising a power supply control circuit for controlling the amount of power supplied to the light receiving element.