JPH01263536A - Apparatus of detecting content ratio of alcohol - Google Patents

Abstract

PURPOSE:To enable the precise detection of the content ratio of alcohol, by providing a light-emitting element and a one-dimensional light position detecting element at one end of a light-transmitting body and by providing a plane of refraction with fuel and a plane of reflection at the other end thereof. CONSTITUTION:A light-emitting element 4 provided at one end of a light-transmitting body 1 is driven 101 to emit a light, and an emission light 14 thereof is made to be incident at an incident angle psi at a point P0 on a plane 15 of refraction at the other end of the light-transmitting body 1 through a stop 12 and a lens 13. Since this plane 15 of refraction is in contact with fuel flowing in from a fuel inlet 17, the incident light 14 is refracted at an angle chi of refraction at the point P0 due to a difference in a refractive index between the fuel and the light-transmitting body 1. Next, the refracted light is transmitted through the fuel, reflected at a point P1 on a plane 11 of reflection, refracted again into the light-transmitting body 1 at a point P2 on the plane 15 of refraction in accordance with the relation formula between the incident angle psi and the angle chi of refraction, and made to be incident on a semiconductor position detecting element 16. Then, photocurrents i1 and i2 from electrodes I1 and I2 of the element 16 are inputted to a detecting circuit 10, amplified 102 and added up 103 thereafter, and the current i2 is divided 104 by an addition value and outputted as a voltage Vout corresponding to a position signal.

Description

[Detailed Description of the Invention] [Industrial Application Meter] This invention is a device that non-contactly determines the properties of fuel supplied to a combustor, etc. Especially for alcohol mixtures used in engines such as automobiles. This invention relates to a device for measuring the alcohol content in D.

[Conventional technology]

In recent years, in order to reduce petroleum consumption in countries such as the United States and Europe, fuel made by mixing alcohol with gasoline has become popular for use in automobiles. If such an alcohol-mixed fuel is used as is in an engine that has been matched to the air-fuel ratio of gasoline, the air-fuel ratio will become lean due to the fact that the stoichiometric air-fuel ratio of alcohol is smaller than that of gasoline. The alcohol content rate is detected to control actuators such as fuel injection valves, and the air-fuel ratio, ignition timing, etc. are adjusted according to the alcohol content rate. Conventionally, as an alcohol content detection device as described above, the one described in, for example, Japanese Unexamined Patent Publication No. 57-51920 is known. This apparatus will be explained with reference to FIGS. 7 and 8. FIG. 7 is a configuration diagram of a fuel control system equipped with a conventional alcohol content detection device, where A is the alcohol content detection device, 20 is the engine, 21 is the fuel injection valve, 22 is the fuel tank, and 23 is the fuel. With the pump, fuel supply pipe 24
The high pressure filter 25 is connected to the high pressure filter 25 via the high pressure filter 25. 26 is a fuel distribution pipe for the fuel injection valve 21, 27 is a fuel pressure regulator, and a fuel return pipe 28 is led to the fuel tank 22. 29 is an air-fuel ratio sensor, 30 is a spark plug, 3
1 is an engine rotation sensor, 32 is an intake pressure sensor, 33 is a throttle valve, and 34 is an air cleaner. Reference numeral 35 denotes a control device into which signals from the alcohol content detection device A, signals from the air-fuel ratio sensor 29, and signals from the engine rotation sensor 31 and intake pressure sensor 32, which are state variables of the engine, are input, and the control device controls the control device according to the inputs. The fuel injection valve 21 and the spark plug 30 are driven by the divided amount.

When the fuel tank 22 is filled with alcohol mixed fuel,
When the engine starts, alcohol mixed fuel is pumped to pump 2.
3, and is led to the alcohol content detection device A through the fuel supply vibrator 24 and the high pressure filter 25, where the alcohol content is measured.

Thereafter, the fuel flows into the distribution pipe 26, a part of which is supplied to the engine through the fuel injection valve 21, and the rest is supplied to the engine through the fuel pressure regulator 2.
7. The fuel is returned to the tank 22 through the fuel return pipe 28. The fuel pressure regulator 27 always maintains the pressure up to the distribution pipe 26 at a constant value, regardless of the amount of fuel injected by the fuel injection valve 21. When the alcohol content measured by the alcohol content detection device A is input to the control device 35, the control device 35 detects the engine rotation sensor 31 and the intake pressure sensor 32.
The engine condition is determined based on signals such as the above, the opening time of the injection valve 21 is controlled to change the amount of fuel supplied to the engine, the air-fuel ratio is detected by the air-fuel ratio sensor 29, and the target value is determined according to the engine condition. The air-fuel ratio is feedback-controlled so that the spark plug 30 is adjusted according to the engine condition.
controls the ignition timing of the

FIG. 8 shows a detailed sectional view of the alcohol content detection device A, in which 1 is a cylindrical transparent body made of optical glass or the like, 2 is a case, and 3 is a space between transparent body 1 and case 2. Fuel seal, 4 is a light emitting element such as an LED, 5 is a light receiving element consisting of a photodiode, 6 is a fuel chamber, 6a is a fuel inlet, 6b
is the fuel outlet. 7a is totally reflected light, 7b is refracted light, 1
0 is a detection circuit that drives the light emitting element 4 and measures the amount of light received by the light receiving element 5. The outer peripheral surface of the transparent body 1 is in uniform contact with the fuel in the fuel chamber 6. The light emitted from the light emitting element 4 is transmitted through the transparent body 1.
The light 7a whose incidence angle on the outer circumferential surface of Since the light 7b is refracted and transmitted through the fuel, the light receiving element 5
receives only light whose incident angle on the boundary surface is greater than or equal to the total reflection angle ψ. When the alcohol content in the fuel changes, the refractive index Nf of the fuel changes and the total reflection angle φ changes, so the amount of light received by the light receiving element 5 changes. By measuring this change in the amount of light received by the detection circuit 10, the alcohol content in the fuel can be determined.

[Problem to be solved by the invention]

However, in such a conventional alcohol content detection device, the amount of light emitted by the light emitting element 4, the light receiving sensitivity of the light receiving element 5, and the peak sensitivity frequency change depending on the temperature, so detection is detected based on engine heat generation and the resulting rise in fuel temperature. When the temperature of the device changes, the amount of light received by the light-receiving element 5 also changes, and the alcohol content in the fuel cannot be determined accurately.

Furthermore, because the angle of total reflection ψ cannot generally be made too small due to the restriction of the refractive index Nd of the light-transmitting body 1, there is a problem that the light-transmitting body 1 cannot be made very short and the device cannot be miniaturized. For these reasons, conventional alcohol content detection devices have to be installed separately from the engine, so they delay the alcohol content of the fuel actually injected from the fuel injection valve 21, especially when starting the engine. Especially when starting the engine after refueling with fuel with a different alcohol content, the alcohol content in the fuel chamber 6 and fuel distribution pipe 26 of the alcohol content detection device A may vary. It is expected that there will be different starting modes, and in such a case, it is expected that in the worst case, a problem will occur where the engine cannot be started.

[Means to solve the problem]

The alcohol content detection device according to the present invention includes a light emitting element and a one-dimensional optical position detection element provided at one end of a transparent body, and a refractive surface and a reflective surface for refraction of fuel at the other end.

[For production]

In this invention, the light emitted from the light emitting element provided at one end of the transparent body is incident on the refractive surface with the fuel at the other end of the transparent body, is refracted into the fuel, and is further reflected at the reflective surface. After that, the light is incident on the refractive surface again, refracted into the light-transmitting body, and incident on the one-dimensional optical position sensing element, and the change in the refractive index of the fuel due to the change in alcohol content is detected at the light incident position on the one-dimensional optical position sensing element. It is measured as a change.

〔Example〕

An embodiment of the present invention will be described below with reference to the drawings. 1st
The figure is a configuration diagram of the alcohol content detection device according to the present invention, and 1 is the same cylindrical transparent body as the conventional device, but the difference is that one end of the column is positioned at a predetermined position with respect to the cylinder axis. It is cut at an angle and forms a refractive surface 15.

11 is a reflective surface, 2 is an aperture, 13 is a lens, 14 is emitted light from the light emitting element 4, and 16 is a one-dimensional optical position detection element,
Here, semiconductor device detection element (hereinafter referred to as PSD)
The case is shown below. Reference numeral 17 denotes a fuel inlet, and the detection circuit 10 includes a constant current drive section 10 that drives the light emitting element 4.
1. Photocurrent preamplifier 102 of PSD 16, adder 1
03, the division section 104 is divided.

A light emitting element 4 arranged at one end of the transparent body 1 is a constant current driver 10.
1 to emit light, the emitted light 14 passes through the aperture 12
The light passes through the lens 13 and enters the refractive surface 15 at the other end of the transparent body 1 at an incident angle ψ at 20 points. Refracting surface 1
5 is in contact with the fuel flowing in from the fuel inlet 17, so the incident light 14 has a refraction angle Z = arcsIN due to the difference between the refractive index Nf of the fuel and the refractive index Nd of the transparent body 1 at 20 points.
It is refracted at (Nd/NfXSINψ). The light refracted at the refraction angle χ at point po transmits through the fuel and reaches the reflecting surface 11.
After being reflected at 21 points, it passes through the fuel again, enters the refractive surface 15 again at 22 points, and is refracted into the light-transmitting body 1 according to the relational expression between the incident angle ψ and the refraction angle χ, and is reflected into the light-emitting element 4. The PSD 16 is located on the same side as the PSD 16. Lens 13 is P
The focal length is selected so that the synchrotron radiation 14 can be completely focused on the SD 16. Note that the other symbols indicate parts corresponding to those in the conventional example shown in FIG. 8, and therefore their explanation will be omitted.

Figure 2 is an explanatory diagram of the optical position detection principle of PSD 16.
SD is an optical gravity center position detection element using a silicon photodiode, and is composed of three layers: a resistive layer (P layer), an intermediate layer, and an N layer.When a light spot is incident, a photocurrent i1. i2 passes through a uniform resistive layer, each electrode II
, 12, and the photocurrent i1. i2 is divided and output in inverse proportion to the distance to the electrode. Now, let the distance from the electrode 11 to the light incidence position be X, and the distance between the electrodes of the PSD be L.
Ruto, position XI! X=LXi2/ (il+i2)
Te is given. At this time, since the position X coincides with the center of gravity of the incident light, the light spot does not necessarily have to have a minute diameter.

In FIG. 1, the photocurrents i1.1 from each electrode 11.12 of PSD i6. i2 is input to the detection circuit 10, amplified by the preamplifier 102, and then 11 and 12 are input to the adder 1.
03, and from the addition result 12, the division unit 104
Dividing i 2/(i 1 + i 2) is performed and output as a voltage Vout corresponding to the position signal X. The refractive index Nf of the fuel changes as the alcohol content in the fuel changes.
When this changes, the refraction angle χ at the refraction surface 15 changes, so the incident position X of the emitted light 14 of the light emitting element 4 on the PSD 16 changes, and the output voltage Vout of the detection circuit changes to a value according to the alcohol content. Become.

Figure 3 shows the change in output voltage ■Out with respect to the methyl alcohol content in gasoline fuel in a structure in which optical glass BK7 with a refractive index Nd = 1.52 is used as the transparent body 1 and the incident angle ψ = 45°. showed that.

Since the refractive index of methyl alcohol is smaller than that of gasoline, as the methyl alcohol content increases, the PSD1
Since the light incident position on the electrode 6 shifts to the electrode 1 side and the photocurrent 11 becomes larger, the output voltage Vout is inversely proportional to the methyl thylcol content. A device that detects engine heat generation and the resulting rise in fuel temperature! When the temperature of the detection device A changes, the amount of light emitted by the light emitting element 4 and the total photocurrent amount of the PSD 16 change, but since the alcohol content is given as a ratio of photocurrents, it is always accurate regardless of the temperature change of the detection device A. It can continuously detect the alcohol content in fuel. Furthermore, since the alcohol content is ultimately detected on a part of the refractive surface 15, the overall length of the light-transmitting body can be shortened compared to conventional devices, so there is an advantage that the detection section can be made smaller.

FIG. 4 is a configuration diagram of the detection unit of the alcohol content detection device, and 128 is the aperture 12, the light emitting element 4, and the lens 13.
It is a holder with a holding function.

The light-transmitting body 1 is cut into a wedge shape at a predetermined angle with respect to the cylinder axis, leaving a predetermined thickness at one end to form a refractive surface 15, and a reflective surface is formed on one end surface of the light-transmitting body 1 by depositing gold or the like. Face 119!
It is formed to serve as a mirror on the back.

Further, the transparent body 1 is insulated from the fuel side by a fuel seal 3 between the case 2 and the case 2, and the case 2 is attached to a high-pressure side pipe near the fuel injection valve 21, such as a fuel distribution pipe 26, through a packing or the like. .

FIG. 5 is a configuration diagram of a detection section showing another embodiment of the present invention, in which the reflective surface 11 is formed on the surface of another plate-shaped transparent body 18 by gold M film vapor deposition, etc. The surface is coated with a light-transmitting retaining II film 19 made of a certain plastic or ceramic thin film. In this way, the polishing surface of the transparent body 1 is reduced, and the polishing cost can be reduced, so that the detection section can be manufactured at a lower cost.

Second, in this embodiment, the reflective surface 11 is formed on the surface of the plate-shaped transparent body 18, but the reflective surface 11 may be formed on the back surface of the transparent body 1 in a similar manner. J: If this is done, the light-transmitting protective film 19 becomes unnecessary.

FIG. 6 is a configuration diagram of a detection section according to still another embodiment of the present invention, in which the reflecting surface 11 is connected to the base member 2 a l of the case 2.
The base member 2a is formed into a metal base member 2a.
The surface of the substrate member 2a is formed by Tifa, or by laminating another metal film on the base member 2a by plating or vapor deposition. In this way, the detection part can be made even more inexpensive by reducing the number of parts, and the detection part can also be made smaller. Wear.

In each of the above embodiments, 1. shows a case where a PSD is used as the one-dimensional optical position detection element 16. However, it is clear to those skilled in the art that the same effect can be expected even if a position sensing element such as a 1-die 4-door array or a COD is used. In addition, insulation from the fuel side of the translucent body 1 can be achieved by filling the space between the translucent body 1 and the case 2 with a sealant, adhering, etc., without relying on the fuel seal 3.
Well, this could also be done by metallizing the peripheral surface of the transparent body 1 and then welding or brazing it to the case 2.

Furthermore, although the above embodiment describes the detection of the alcohol content in fuel, it is also widely applicable to devices for measuring the refractive index of other liquids.

[Advantages of the Invention] As explained above, the present invention has the following advantages:1. A light emitting element and a one-dimensional optical position detection element are provided at one end of the transparent body, and a reflective surface such as a refraction surface for fuel is provided at the other end. It can be installed in the pipe near the fuel injection valve, so that the a,
++-Coal content can always be detected continuously without delay. Also, the accuracy of the detection device is important regardless of temperature changes (it should be able to detect alcohol content).

[Brief explanation of the drawing]

Fig. 1 is a block diagram of an alcohol content detection device according to an embodiment of the present invention, Fig. 2 is an explanatory diagram of the optical position detection principle of PSD, and Fig. 3 is an output voltage for methanol content in gasoline fuel. FIG. 4 is a sectional view of the detection unit of the alcohol content detection device, FIG. 5 is a sectional view of the detection unit according to another embodiment, and FIG. 6 is a sectional view of the detection unit according to another embodiment. FIG. 7 is a block diagram of a conventional alcohol content detection device) 2 fuel control system, and FIG. 8 is a block diagram of a conventional alcohol content detection device. 1. Translucent body, 2. Case, 4... Light emitting element, 1°...
Detection circuit, 11. Reflection surface, 12 Aperture, 13. Lens, 14. Synchrotron radiation, 15. Refraction surface, IG.-Dimension forward W detection element, 17.. Fuel inlet, 18. Plate-shaped transparent Light body, 19 ・Transparent protective film. Note that the same reference numerals in the figures indicate the same or equivalent parts.

Claims (1)

[Claims] In a device that detects the alcohol content in fuel by detecting the refractive index of the fuel, a light-emitting element and a one-dimensional optical position detection element are provided at one end of the transparent body, and a refractive surface and a reflective surface that meet the fuel are provided at the other end. The refracted light that is incident on the refracting surface from the light emitting element is reflected on the reflective surface, and then the refracted light is incident on the refracting surface again, and the refracted light is incident on the one-dimensional position sensing element. Alcohol content detection device.