JPS63215945A - Mixing ratio detector for fluid such as gasoline-alcohol - Google Patents

Abstract

PURPOSE:To achieve a higher measuring accuracy, by connecting a light emitting element to an output terminal of an operational amplifier while an electric resistor is connected in series to the light emitting element to make up for temperature characteristic of the light emitting element. CONSTITUTION:In a sensor 1, a voltage is applied to an operational amplifier 100 from a storage battery B and the voltage being amplified is applied to a light emitting element 9 through output terminals (m) and (n) to emit light. Out of the light of the element 9, a part is directed to a light transmitting body 3, totally reflected on the internal side thereof and passes through the light transmitting body 3 to be incident into a light receiving element 14. Photoelectric characteristic of the elements 9 and 14 varies with changes in environmental temperature or the like in which the sensor 1 is arranged. The element 9 is incorporated into a temperature compensation circuit D and hence, photoelectric characteristic of the elements 9 and 14 changes with a rise in the ambient temperature. Thus, even under such a circumstance that an output of the sensor 1 is forced to lower, the voltage of the element 9 falls and a voltage drop generated in a resistor 101 by a current I flowing through the element 9 and an electric resistor 101 is controlled to increase the voltage and the current I rises to make up for photoelectric characteristic or the like of the elements 9 and 14.

Description

[Detailed Description of the Invention] [Industrial Application Field] This invention emits light toward a transparent body through which a fluid flows on the outer peripheral side surface, and refracts the fluid against the transparent body by a light layer that passes through by total reflection. The present invention relates to a liquid mixture ratio detection device to which a ratio can be determined, and particularly to a liquid mixture ratio detection device for gasoline-alcohol, etc., which is improved so as to be able to compensate for the temperature characteristics of a light emitting element.

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

By the way, the photoelectric characteristics of the light-receiving element and the light-emitting element, which are the main components of the sensor, change with changes in the humidity and temperature of the ring in which the sensor is arranged, and the critical angle ( Since the refractive index (refractive index) also changes with temperature fluctuations, there is a risk that the sensor will not be able to maintain high measurement accuracy unless some kind of temperature compensation means is taken. Therefore, in recent years, it is expected that a sensor that can provide a temperature compensation function with a relatively simple configuration will appear. , [Object of the Invention] This invention was made in response to the above-mentioned circumstances, and its purpose is to realize temperature compensation of a light emitting element with a relatively simple configuration, maintain a high measurement N degree, and reduce cost. It is an object of the present invention to provide a device for detecting a mixture ratio of liquids such as gasoline and alcohol, which has an excellent effect of being advantageous and leading to miniaturization of the whole.

[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 its outer peripheral surface, and a light-transmitting body of this transparent body.
- A light emitting element that generates light incident in the axial direction from an end, and a light transmitting element 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 transparent body with respect to the mixed fluid. a light receiving element that receives and outputs light that is totally reflected on the inner surface of the body; the light emitting element is connected to an output terminal of an operational amplifier; and an electric resistor for compensating for the temperature characteristics of the light emitting element is connected to the light emitting element. A configuration in which the device is connected in series is adopted.

[Operation and Effects of the Invention] According to the invention configured as described above, the light emitting element is connected to the output terminal of the operational amplifier, and an electric resistor for compensating for the temperature characteristics of the light emitting element is connected in series with the light emitting element. By connecting the light emitting element to the arithmetic element, the temperature compensation function of the light emitting element is exerted and high measurement accuracy is maintained.Moreover, it requires a relatively simple configuration of connecting the light emitting element to the arithmetic element, which is advantageous in terms of cost and leads to overall miniaturization. It has such excellent effects.

[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.

f1 In FIG. 1, 1 is a sensor for detecting the refractive index,
This includes a cylindrical bobbin 2, into which a rod-shaped transparent body 3 made of optical glass is fitted liquid-tightly via an O-ring 4.5.

An annular center +ff16 is formed on 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. Bobbin 2
A cap 10 having a light emitting element 9 is fitted into the upper end opening, and in this state, the light emitting element 9 faces the center of the upper end surface of the transparent body 3. Further, a case 12 having a glass window 11 is fitted into the lower end opening of the bobbin 2.
is opposed to 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 .

The sensor 1 configured as described above is used as an inlet body 8 for a vibrator 23a connecting a fuel tank 20 and a pressure regulator 23 in an electronic fuel injection system shown in FIG. 3, which will be described later.
and is attached via an ejection roller body 7. 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. 2, an electric circuit for temperature compensation in which the light emitting element 9 is incorporated will be described.

The operational amplifier 100 uses the storage battery B as a power source, and
The light emitting element 9 is connected to the output terminal 100b. An electric resistor 101 for voltage drop is connected in series to the light emitting element 9. A voltage obtained by dividing the storage battery B using a resistor is applied to the non-inverting input terminal 100a, and the inverting input 1ooc is connected to the output terminal 100b.

Next, FIG. 3 is a diagram of an operation control system of an automobile engine incorporating an electronic fuel injection device to which this sensor 1 is applied. In FIG. 3, 37 is an engine cylinder, 50 is an engine key switch, 51 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 pipe 23a, and the 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, 30
31 is an air cleaner, 31 is an air 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 sensor 1, from storage battery B to operational amplifier 1
00 (voltage is applied and the amplified voltage is output terminal n,
+a 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.

Thus, the light incident on the light receiving element 14 is converted into a current and supplied from an operational amplifier (not shown) to the control circuit 51 via the input section 51a. 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, the photoelectric characteristics of the light emitting element 9 and the light receiving element 14 change with fluctuations in the environmental temperature in which the sensor 1 is placed.
In addition, the critical angle (refractive index) of the transparent body 3 at the surface in contact with the mixed liquid changes as the temperature changes, so unless some kind of temperature compensation measure is taken, there is a risk that the sensor 1 will not be able to maintain high side accuracy. be.

As a countermeasure against this, according to the above configuration, the light emitting element 9 is incorporated into the temperature compensation circuit, so that the photoelectric characteristics of the light emitting element 9 and the light receiving element 14 and the refractive index of the mixed liquid change as the ambient temperature rises. As a result, the output of sensor 1 is as shown in Figure 4.
Even if the voltage drops as shown in FIG. 5, the voltage drop of the light emitting element 9 (VLED) falls as shown in FIG.
The voltage drop (Vd) generated in the electrical resistor 101 due to the current I flowing through the light emitting element 9 and the electrical resistor 101 is the sixth
Since the current I is controlled to increase as shown in the figure, the current I increases, and the fluctuations in the photoelectric characteristics of the light emitting element 9 and the light receiving element 14 and the refractive index of the mixed liquid are compensated for as shown in FIG. Therefore, it is possible to contribute to maintaining accurate measurement accuracy of the sensor 1 almost regardless of fluctuations in ambient temperature.

However, the humidity compensation circuit requires a simple configuration such as providing an operational amplifier 100 and connecting an electric resistor 101 in series to the light emitting element 9, and the overall structure does not become large and can be made compact, reducing costs. It is also advantageous.

Note that a light receiving element 14 and a light emitting element 9 are provided on both sides of the transparent body 3.
The present invention is not limited to those in which the light-receiving element and the light-emitting element are arranged only on one end surface of the light-transmitting 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, it can be applied to systems that continuously monitor the concentration of salt and sugar in the food and animal feed manufacturing process in the food industry instead of automobile engines.

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 vertical cross-sectional view of the sensor shown together with the pipe, Figure 2 is an electrical wiring diagram of the temperature compensation circuit, Figure 3 is a diagram of the operation control system of an electronic fuel injection device in an automobile engine, and Figure 4 is a diagram showing the voltage and temperature. A graph showing how the voltage drop of the light emitting element changes as the temperature rises. Figure 5 is a graph showing how the voltage drop of the light emitting element changes with the temperature. Figure 6 shows how the voltage drop due to the electric resistor is controlled by the voltage drop of the light emitting element. FIG. 7 is a graph showing how the refractive index is compensated as the temperature changes. In the diagram 1...Sensor -2...Case 9...
Light emitting element 14... Light receiving element 3... Translucent body D.
・・Temperature compensation circuit 101 ・・Electric resistor 100・
・Operation amplifier

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 light-emitting element is connected to an output terminal of an operational amplifier, an electric resistor for compensating for the temperature characteristics of the light-emitting element is connected in series with the light-emitting element, and a constant voltage is applied. Features: A device for detecting fluid mixture ratios such as gasoline and alcohol. 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 device for detecting a mixture ratio of a liquid such as gasoline and alcohol according to claim 1, wherein the transparent body is made of cylindrical optical glass.