JPS63210647A - Mixing ratio detector for fluid such as gasoline-alcohol - Google Patents

Abstract

PURPOSE:To lower material cost with a reduction in the area of a photo detector, by setting the shape of the photo detector so as to correspond to a sectorial surface formed by two radial lines placing it therebetween in a circular area which is formed by light totally reflected on a light transmitter. CONSTITUTION:In a sensor 1, a voltage is applied from a control section and a light emitting element 9 emits light. Out of the light, a beam directed at a light transmitter 3 and totally reflected on the inner side thereof passes through the light transmitter 3 along the axis thereof and enters a photo detector 14 with the shape so set to cover an area C surrounded by radial lines (a) and (b) in a circular area of light by way of a glass window 11. A mixed fuel of gasoline and alcohol is flowing in contact with a circumferential surface of the light transmitter 3. Since refractive index changes as the mixing ratio of the level varies, a critical angle of light from the light emitting element 9 changes with respect to the light transmitter 3. The light entering the light emitting element 14 is converted into an electrical signal and the mixing ratio and a data related to the quantity of light entering the photo detector 14 is supplied to a control circuit according to changes in the refractive index.

Description

[Detailed Description of the Invention] [Industrial Application Field] This invention emits light toward a transparent body through which a fluid flows on its outer peripheral side surface, and changes the refractive index of the transparent body with respect to the fluid by the amount of light that passes through total reflection. The present invention relates to a fluid mixture ratio detection device that is adapted to be able to determine, and in particular, to a fluid mixture ratio detection device for gasoline-alcohol, etc. that has been improved so that the shape of the light receiving element that receives totally reflected light can be small.

[Prior art and its problems] For example, in recent years, it has been considered to use a mixed fluid of gasoline and alcohol as fuel in internal combustion engines of automobiles. In order to obtain good engine output with this mixed fuel, it is necessary to continuously detect the mixture ratio and feed this information back to the automatic combustion control system to ensure the optimal air-fuel ratio and ignition timing.

For this reason, a fuel mixture ratio detection device is required, and this detection device is equipped with a light-transmitting body with a light-emitting element and a light-receiving element arranged at both ends, and is designed to cause the mixed fuel to flow around the outer circumferential surface of the light-transmitting body. It is composed of

Then, the light emitting element emits light toward the transparent body, and the light receiving element receives the light that passes through total reflection, and detects the output generated from this element. The refractive index of the transparent body with respect to the mixed fuel is measured based on this output, and the fuel mixture ratio is determined based on this refractive index.

Incidentally, the light receiving element is generally made of a silicon semiconductor, and is sealed in a case equipped with a glass window to prevent foreign matter from entering. For this reason, a predetermined distance inevitably occurs between the end face of the light-transmitting body and the light-receiving element. Because of this distance, the circular area of the light that enters the photodetector due to total reflection becomes relatively large, and in order to receive this light all over without leaking, it is necessary to use a photodetector with a large photodetection area. be. As a result, the material ratio of the light-receiving element becomes bulky, which is disadvantageous in terms of cost.

[Purpose of the invention] This invention was made in response to the above-mentioned circumstances, and its purpose is to form a light-receiving element with a small area, thereby reducing material costs, which is cost-effective, and leads to overall miniaturization. The object of the present invention is to provide a device for detecting a mixture ratio of a fluid such as gasoline and alcohol, which has an excellent effect of not reducing light reception accuracy.

[Means for Solving the Problems] The present invention provides a rod-shaped transparent body in which mixed fluids of different types are made to flow in contact with each other on the outer circumferential surface, and a rod-shaped transparent body in which a mixture of fluids of different types flows in contact with each other on the outer circumferential surface, and a light-transmissive body that enters the light in the axial direction from one end of the transparent body. a light emitting element that generates light that
a light-receiving element that receives and outputs the light that is totally reflected on the inner surface of the light-transmitting body among the light from the light-emitting element in order to measure the mixing ratio of the mixed fluid based on the refractive index of the light-transmitting body with respect to the mixed fluid; , the shape of the light-receiving element is set to correspond to a fan-shaped surface formed by being sandwiched between at least two radial direction lines in a circular region formed by light totally reflected by the light-transmitting body. is adopted.

[Operation and Effects of the Invention] According to the invention configured as described above, the fan-shaped area formed by being sandwiched between at least two lines in the radial direction in the circular area formed by the light totally reflected on the transparent body. By setting the shape of the light-receiving element to correspond to the surface, a light-receiving element with a small area can be used, which reduces material costs, is cost-effective, and leads to a smaller overall size.However, the amount of light received by the light-receiving element is reduced. However, since all the light components in the radial direction can be covered, the rate of change of the light receiving aperture remains the same as before, and the light receiving accuracy does not deteriorate, which is an excellent effect.

[Embodiment] An embodiment in which the present invention is applied to an internal combustion engine of an automobile will be described below with reference to the drawings.

First, in FIGS. 1 and 2, reference numeral 1 denotes a sensor for detecting a refractive index, which is equipped with a cylindrical bobbin 2.
Inside, a rod-shaped transparent body 3 made of glass is attached to an O-ring 4.
．． 5 and are fluid-tightly fitted. An annular space 6 is formed in the inner peripheral surface of the bobbin 2 so as to surround the outer surface of the transparent body 3 by forming a recess 2a in the inner peripheral surface.

Further, on the outer surface of the bobbin 2, an ejection roller body 7 and an input roller body 8 are erected so as to communicate with the annular space 6, respectively. A cap 10 having a light emitting element 9 is fitted into the upper end opening of the bobbin 2. In this state, a cap 10 having a light emitting element 9 is fitted.
is opposed to the center of the upper end surface of the transparent body 3. Further, a case 12 having a glass window 11 is provided at the lower end opening of the bobbin 2.
are fitted, and the window 11 faces the lower end surface of the transparent body 3 in a close state. The case 12 has a sealed structure in which nitrogen gas or the like is sealed, and a thin substrate 13 is disposed parallel to the glass window 11. In this state, a flat light receiving element 14 made of a silicon semiconductor is provided on the substrate 13 so as to face the lower end surface of the transparent body 3 . This light receiving element 14 is constructed as follows. That is, a circular area C is set as shown in FIG. 2, in which light from the light emitting element 9, which has passed through the light transmitting body 3 by total reflection, is projected onto the substrate 13 via the glass window 11, as will be described later.

Furthermore, as shown by the two-dot chain line in the figure, the previous circular area C
Assume a rectangular region R that completely covers the entire area. Then, from the center of the circular region C, a region surrounded by two radial lines a1b forming an angle of 45 degrees and a rectangular region R, and corresponding to the fan-shaped surface of the circular region C, is used as the light receiving element 14. The shape is the same as that of 1 (shown by the dotted pattern in Figure 2). In this case, the rectangular area 1 may be circumscribed to the circular area C, and the angle formed by the FIi sword direction is not limited to 45 degrees.

The sensor 1 configured as described above is connected to a pipe 23a connecting a fuel tank 20 and a pressure regulator 23 through an inlet body 8 and an outlet body 7 in an electronic fuel injection system shown in FIG. 4, which will be described later. installed. In this state, the mixed fuel of gasoline and alcohol enters the annular space 6 from the pipe 23a and contacts the outer surface of the transparent body 3.

Next, referring to FIG. 3, the electrical connections among the light receiving element 14, the compensation light receiving element 106, and the light emitting element 9 will be described.

The amount of light emitted by the light receiving element 9 changes depending on the environmental temperature. Further, the output voltage of the measurement light receiving element 14 changes depending on the environment even if the mixing ratio of the measurement liquid mixture is constant. Therefore, the temperature compensation circuit 206 of this embodiment controls the light emission amount of the light emitting element 9 so that the output of the compensation light receiving element 106 becomes constant, and the light emission amount compensation circuit section 26 keeps the output of the output light receiving element 14 constant.
1, and a received light amount compensation circuit 262 that compensates for a critical angle due to a change in mixing temperature based on the amount of power supplied to the light emitting element 9 by the light emitting layer compensation circuit section 261.

The light emission amount compensation circuit 261 includes a first light speed measuring section 263 that converts the amount of light received by the compensation light receiving element 106 into a voltage value, and
The control unit 264 applies the output of the light amount measurement unit 263 to the light emitting element 9 so that the output becomes equal to the value of BATl.

The first light presentation measuring section 263 is composed of a first operational amplifier OP1 which inputs the potential difference between both terminals of the compensation light receiving element 106, and resistors R1 and R2. When the environmental temperature of the sensor 1 decreases), the output of the first operational amplifier OP1 increases.

The control unit 264 controls the output of the first operational amplifier OP1 and the base rI! of the first battery BAT1! It consists of a second operational amplifier OP2 that inputs a voltage and controls the output, a capacitor C1 for hunting prevention, and a resistor R3, and when the time between light emission of the light emitting element 9 increases (when the environmental temperature of the mixed sensor 1 decreases) , the voltage supplied to the light emitting element 9 is decreased, and when the amount of light emitted by the light emitting element 9 decreases (as the environmental temperature of the mixture ratio sen+J1 increases), the voltage supplied to the light emitting element 9 is increased.

As a result, even if the environmental humidity of the mixture ratio sensor 1 changes,
The amount of light emitted by the light emitting element 9 is set such that the output of the measuring light receiving element 14 is constant.

The received light amount compensation circuit section 262 includes a voltage source 265 that converts the voltage supplied to the light emitting element 9, a second light amount measuring section 266 that converts the amount of light received by the measuring light receiving element 4 into a voltage value, and and a subtraction section 267 that subtracts the output value of the voltage holo 7265 from the output value of the measurement section 266.

The voltage follower 265 inputs the input voltage from the light emitting element 9 and its own output, and connects the third operational amplifier ○P3, the resistor R4,
R5, the input voltage from the light emitting element 9, which has a value corresponding to changes in environmental temperature, can be taken out as an output without voltage drop.

The second light amount measuring section 266 includes a fourth operational amplifier OP4 that receives as input the potential difference between both terminals of the measuring light receiving element 14, and resistors R6, R7, and R8. This fourth operational amplifier OP
The output of No. 4 increases as the alcohol percentage in the mixture to be measured increases. On the other hand, assuming that the mixing ratio of the liquid mixture is constant, the output voltage of the fourth operational amplifier OP4 becomes smaller as the environmental temperature of the mixing ratio sensor 1 becomes higher.

The subtraction unit 267 outputs the output of the third operational amplifier OP3 and the fourth operational amplifier OP3.
A fifth operational amplifier OP5 inputs the output of the divided voltage of the operational amplifier OP4 and outputs a value obtained by subtracting the output value of the third operational amplifier ○P3 from the divided voltage value of the fourth operational amplifier OP4, and resistors R9, R10, and R11. It is assumed that the output of the subtraction unit 267 has been compensated for the critical angle due to the temperature change of the mixed liquid.

Next, FIG. 4 is a diagram of an operation control system for an automobile engine incorporating an electronic fuel injection device to which this sensor 1 is applied. In FIG. 4, 37 is an engine cylinder, 50 is an engine key switch, 151 is a control circuit, 55 is a storage battery as a power source, and 20 is a fuel tank. 21 is a fuel pump, 23 is a pressure regulator connected to the fuel tank 20 via a vibrator 23a, and a sensor 1 according to the present invention is provided in the pipe 23a. 24 is an injector, 26 is a cold start injector, 25 is an ignition coil, 3
0 is an air cleaner, 31 is an F valve, 32 is an air flow meter, 33 is a throttle valve, 34 is a throttle valve position sensor, 35 is an intake pipe, and 36 is an exhaust pipe. Further, 52 is an oxygen sensor, and 53 is an engine coolant temperature sensor.

Next, the above configuration will be explained along with the operation of the sensor 1.

When the key switch 50 is operated, the engine is started and power is supplied to the control circuit 51. Accordingly, the mixed fuel of gasoline and alcohol in the fuel tank 20 is supplied to the injector 24 via the fuel pipe 22 by the fuel pump 21. The injector 24 injects into the intake pipe 35 at a time and in an amount calculated by the control circuit 51 to be optimal for the operating conditions of the engine.

On the other hand, in the sensor 1, a voltage is applied from the control section 264 in FIG. 3 to the light emitting element 9, and the light emitting element 9 emits light. Of the light emitted from the light emitting element 9, as shown in FIG. The light enters the light receiving element 14 via the light receiving element 11 .

At this time, the mixed fuel of gasoline and alcohol is flowing in contact with the outer peripheral surface of the transparent body 3, and the refractive index of the mixed fuel changes every time the mixing ratio of gasoline and alcohol changes. The critical angle of light from the light emitting element 9 with respect to the transparent body 3 changes. The relationship between the mixture ratio of gasoline and alcohol and the amount of light incident on the light-receiving element 14 is prepared in advance from the change in the refractive index, and these data are input to the control circuit 51.

Therefore, the light incident on the light receiving element 14 is
The subtracter 267 inputs the output of the third operational amplifier OP3 and the divided voltage output of the fourth operational amplifier OP4, and the divided voltage value of the fifth operational amplifier OP5 to the fourth operational amplifier OP4 and the third operational amplifier OP3.
An output corresponding to the difference between the output value and the output value is supplied to the control circuit 51 via the input section 51a as a temperature compensation output. Based on the magnitude of this output, the control circuit 51 calculates the optimal injection amount and optimal injection timing for the injector 24 to maintain a good engine output.

By the way, according to the above configuration, the shape of the light receiving element 14 is set so as to cover the area surrounded by the lines a and b in the radiation direction in the circular area C of light. Unlike conventional light-receiving elements, which require a light-receiving area that surrounds the light-receiving area, the light-receiving element 14 is small, which saves material costs and is advantageous in terms of manufacturing costs, leading to overall compactness. Furthermore, since the light-receiving element 14 includes all the light components in the radiation direction, highly accurate detection is always performed without any omissions in the detection of the light-receiving element 14.

Next, another embodiment of the present invention will be described with reference to FIGS. 5 and 6.

These examples differ from the above examples in the following points:
This is because the shape of the light-receiving element has been changed.

That is, in the one shown in FIG. 5, the shape of the light receiving element 15 is as follows.
The angle formed by the lines a and b in the radial direction in the circular region l#IC is set to be 90 degrees.

On the other hand, the shape of the light receiving element 16 in FIG. 6 is set so that the angle formed by the lines a and b in the radiation direction in the circular region C is 180 degrees.

A similar effect can be obtained by setting in this way.

In this case, the same parts have been given the same reference numerals and only the different parts have been described.

When setting the shape of the light receiving element, it goes without saying that the angle formed by the line in the radiation direction of the circular region C is not limited to that of the above embodiment.

In addition, a light receiving element 14 and a light emitting element 9 are provided at both ends of the transparent body 3.
The present invention is not limited to those in which a light-receiving element and a light-emitting element are arranged only on the - side end face of a transparent body.

Furthermore, the present invention is not limited to mixed fuels of gasoline and alcohol, but can also be applied to other fluids in which the concentration of components is considered instead of the mixing ratio. In this case, instead of an automatic medium engine, it can be applied to a system in the food industry that continuously monitors the concentration of salt or sugar in a manufacturing T culm for food or animal feed.

In addition, various changes can be made in the specific implementation without departing from the gist of the invention.

[Brief explanation of the drawing]

Figure 1 is a cross-sectional view of the sensor shown with a pipe, Figure 2 is a plan view showing the shape of the light receiving element, Figure 3 is an electrical wiring diagram, and Figure 4 is a diagram of the operation control system of an electronic fuel injection device in an automobile engine. , FIG. 5, and FIG. 6 are views corresponding to FIG. 2 showing other embodiments of the present invention. In the diagram 1...Sensor 12...Case 9...
Light emitting element 14.15.16... Light receiving element 3...
Translucent body C...circular area

Claims (1)

[Scope of Claims] 1) A rod-shaped transparent body in which mixed fluids of different types are made to flow in contact with each other on the outer peripheral surface, and a light emitting device that generates light that is incident in the axial direction from one end of the transparent body. receiving and outputting light from the light emitting element that is totally reflected on the inner surface of the transparent body in order to measure the mixing ratio of the mixed fluid based on the refractive index of the transparent body with respect to the mixed fluid; a light-receiving element, the shape of the light-receiving element is configured to correspond to a fan-shaped surface formed by being sandwiched between at least two radial direction lines in a circular area formed by light totally reflected by the light-transmitting body; A fluid mixture ratio detection device for gasoline-alcohol, etc., characterized in that: 2) The device for detecting a mixture ratio of a fluid such as gasoline and alcohol according to claim 1, wherein the fluid is a fuel for an internal combustion engine and is composed of gasoline and alcohol. 3) The apparatus for detecting a mixture ratio of a fluid such as gasoline and alcohol according to claim 1, wherein the transparent body is made of cylindrical optical glass.