JPH01270646A - Apparatus for detecting alcohol content - Google Patents

Abstract

PURPOSE:To continuously and accurately detect alcohol content without delay by a small-sized apparatus even when the temp. of the apparatus is changed, by forming the contact plane with fuel on the way of an elongated light conductor and providing a light projector to one end surface of the light conductor while providing a photodetector to the other end surface thereof. CONSTITUTION:The clamping angles (incident angle of propagation light) theta of many elongated light conductors 1 and a contact plane 2 are equal on an incident side and an opposite side, and set so as to become small toward the light conductor 1 on this side. LEDs 3 are provided to one ends of the light conductors 1 and photodiode elements 5a (array 5) are provided to the other ends thereof. When the LEDs 3 emit lights by a drive circuit, lights are transmitted to the respective light conductors 1 in equal quantity through average diffusion bodies 4. When the incident angle thetais smaller than the total reflection angle determined by the refractive index (large as alcohol content becomes low) of fuel and that of each light conductor 1, incident light is not propagated to each element 5a and no photocurrent flows. Therefore, the photocurrent of each element 5a is measured and the position signal proportional to the number of the element becoming a predetermined value or more in a photocurrent is outputted to make it possible to detect alcohol content.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a device for non-contact determining the properties of fuel supplied to a combustor, etc., and particularly relates to a device for non-contact determining the properties of fuel supplied to a combustor, etc. The present invention relates to a device for measuring the alcohol content of alcohol.

[Prior Art] Recently, in the United States, Europe, and other countries, fuel made by mixing alcohol with gasoline has become popular for use in automobiles in order to reduce oil consumption. If such an alcohol-mixed fuel is directly used 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 in the fuel 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. Conventionally, as an alcohol content detection device as described above, the one described in, for example, Japanese Patent Laid-Open No. 57-51920 is known. Such a conventional device is shown below in FIG.
This will be explained in FIG.

FIG. 8 is a block diagram showing a fuel control system equipped with a conventional alcohol content detection device, in which A indicates the alcohol content detection device, 20 is an engine of an automobile, etc., and 21 is fuel for supplying fuel to the engine. Injection valve, 22 is fuel tank, 23
is a combustion pump that sucks up the fuel in the tank 22 and is connected to the high-pressure filter 25 via the fuel supply pipe 24. 26 is a fuel distribution pipe connected to the injection valve 21;
27 is a fuel pressure regulator 27 connected to this distribution pipe 26
, the fuel return pipe 28 is connected to Jr. tank 2.
It is inserted in 2. 29 iJ air-fuel ratio sensor, 30 a spark plug, 3I a sensor for detecting the rotational force of the engine 20, 32 an intake pressure sensor, 33 a throttle valve, and 34 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, signals from the engine rotation sensor 31 and intake pressure sensor 32, which are state quantities of the engine, etc. are input, and the control device operates according to the inputs. The fuel injection valve 21, spark plug 30, etc. are driven by the control amount. When the alcohol-mixed fuel is supplied to the fuel tank 22, when the engine starts, the alcohol-mixed fuel is pressurized by the fuel pump 23 and guided to the alcohol content detection device through the fuel supply pipe 24 and the high-pressure filter 25. The content is measured. The fuel then flows into the fuel supply pipe 26, where part of the fuel is supplied to the engine through the fuel injection valve 21, and the rest is returned to the fuel tank 22 through the fuel pressure I/regulator 27 and fuel return pipe 28.

The fuel pressure regulator 27 always maintains the pressure up to the fuel 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 3.
The engine condition is determined based on the 2nd class signal, and the fuel injection valve 2
Fuel supply to the engine by controlling valve opening 1.1
To change the world, the air-fuel ratio is detected by the air-fuel ratio sensor 29, and the air-fuel ratio is feed-hack controlled so that it reaches the target value according to the engine condition, and the ignition timing of the ignition plaque 30 is adjusted according to the engine condition. is under control.

FIG. 9 is a configuration diagram of a conventional alcohol content detection device, where 37 is a cylindrical transparent body made of optical glass or the like, 6 is a case, and 38 is a cylindrical transparent body 37 and case 6. A fuel seal between 3 and 3 is a light emitting element consisting of an LED, 3
664 photodiodes, 39 is a twist I chamber, 39a is a fuel inlet, 39b is a fuel outlet I'', 40a
40b is the totally reflected light, 40b is the refracted light, and 10 is a detection circuit that drives the light emitting element 3 and measures the amount of light received by the light receiving element 36. The outer peripheral surface of the cylindrical transparent body 37 uniformly contacts the fuel in the three fuel chambers. The light emitted from the light emitting element 3 passes through the cylindrical transparent body 3
7, that is, the interface with the fuel, but at this time, due to the difference between the refractive index Nf of the fuel and the refractive index Nd of the cylindrical transparent body 37, the angle of incidence on the interface becomes the total reflection angle ψ -arcsI
The light 40a of N (Nf/Nd) or more reaches the light receiving element 36 through the total anti-total refraction of LIJ, and the light 40b whose incident angle is smaller than the total reflection angle ψ is refracted and transmitted into the fuel.
6 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 ψ changes, so the amount of light received by the light receiving element 36 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.

(Problems to be Solved by the Invention) However, in accordance with such a conventional alcohol content detection device, the amount of light emitted by the light receiving element 3, the light receiving sensitivity of the light receiving element 36, and the peak sensitivity frequency change depending on the temperature of the engine. When the temperature of the detection device changes due to the heat generated by the fuel and the resulting rise in fuel temperature, the amount of light received by the light receiving element 36 also changes, making it difficult to accurately determine the alcohol content in the fuel. Refractive index N of columnar transparent body 37
Because the total reflection angle ψ cannot be made too small due to the restriction of d,
There was a problem in that the cylindrical transparent body 37 could not be made very short and the device could not be miniaturized. For these reasons, conventional alcohol content detection devices have to be installed separately from the engine, so they do not actually detect combustion, especially when starting the engine. '1 It is impossible to detect the alcohol content of the fuel injected from the injection valve 21 without delay, especially when starting the engine after refueling with fuel with a different alcohol content. Alcohol content in the fuel chamber 39 and fuel distribution pipe 26 of device A is expected to result in starting motors with a difference in t, and in such a case, it is expected that in the worst case, a problem will occur where the engine cannot be started.

This invention was made to solve the above-mentioned problems, and it is possible to detect the alcohol content in fuel continuously and accurately without any delay even if the device temperature changes, and it is also possible to The purpose is to obtain a content rate detection device.

(Means for Solving the Problems) An alcohol content detection device according to the present invention includes a plurality of elongated light guides, in which a plane tangential to the fuel is formed in the middle, and a light projector is provided on one end surface of the elongated light guides. , a photoreceptor is provided on the other end surface.

[For production]

In this invention, light is incident on a tangential plane from a light emitter at one end of an elongated light guide at different average incident angles, and the total reflected light on this tangential plane is transmitted to a light receiver at the other end of each elongated light guide. The alcohol content in the fuel can be detected by detecting the refractive index of the fuel from the light intensity distribution on this photoreceptor.

〔Example〕

An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a perspective view showing the detection part of an embodiment of the alcohol content detection device of the present invention, in which 1 is an elongated light guide, and 2 is a plane tangential to the fuel provided in a part of the way of the elongated light guide. , 3 is a light emitting element made of, for example, an LED, 4 is an average diffuser, 5 is a photoreceptor, and here an example using a photodiode array is shown. 5a is a photodiode element of the photodiode array 5, 6 is a case, 6a is a flange of the case 6. The angle θ between each elongated light guide 1 and the tangential plane 2 is equal on the incident side and the opposite side, and the angle θ, that is, the average angle of incidence θ of the propagating light of the elongated light guide 1 on the tangential plane 2 is as shown in the figure. In this case, the elongated light guide in the front is set to be very small. A light emitting element 3 is provided at one end of the elongated light guide 1 so that the amount of light incident on each elongate light guide 1 through the average diffuser 4 is equal. At the other end of the elongated light guide 1 with the tangential plane 2 in between, a photodiode element 5a is provided corresponding to each of the elongated light guides 1, and each photodiode element 5a forms a photodiode 5 as a whole. .

The case 6 is attached to a conduit near the fuel injection valve 21, such as the fuel distribution pipe 26, through a gasket or the like by means of a flange 6a so that the tangential surface 2 of the upper part of the case 6 is exposed to the fuel.

FIG. 2 is a block diagram of one embodiment of the alcohol content detection device of the present invention, in which 10 is a detection circuit, 101 is a light emitting element drive circuit, and 102 is a light amount distribution detection circuit, which is connected to the photodiode array 5. A signal is being input. When the light emitting element 3 emits light by the light emitting element driving circuit 101, an equal amount of light is transmitted to each elongated light guide 1 of the m tree through the average diffuser 4. In the figure, N=i-th and N=j
The figure shows the second elongated light guide 1. The light incident on the i-th elongated light guide 1 propagates through the elongated light guide and impinges on the tangential plane 2 between this elongate light guide and the fuel at an average angle of incidence θi. At this time, the average incident angle θi is determined by the total reflection angle ψ−a determined by the refractive index Nf of the fuel and the refractive index Nd of the elongated light guide 1.
If it is smaller than rcsIN (Nf/Nd), as shown in the figure, most of the incident light is transmitted into the fuel at the average refraction angle χi and does not propagate to the other end of the elongated light guide 1. i-th photodiode element 5 corresponding to
The amount of light received by a is almost zero, and almost no photocurrent flows from the i-th photodiode element 5a.

On the other hand, the light incident on the j-th elongated light guide 1 is incident on the tangential plane 2 between this elongated light guide and the fuel at an average incident angle θJ that is larger than the total reflection angle ψ. Most of the light is totally reflected and propagated to the other end side of the elongated light guide 1, and is received by the corresponding j-th photodiode element 5a, and a large photocurrent i flows from the j-th photodiode element 5a. Since the elongated light guides 1 are arranged so that the angle θ, that is, the average angle of incidence θ, increases as N increases, in the figure, the L side corresponding to the elongated light guide whose average angle of incidence θ is smaller than the total angle of incidence ψ Almost no photocurrent flows from the N-1 to j-1th photodiode elements 5a (indicated by diagonal lines), and a small photocurrent flows from the R-side photodiode elements 5a from N=jth onwards. I flows. The light amount distribution detection circuit 102 includes each photodiode element 5.
Measure the photocurrent of a and output a position signal proportional to the element number j at which the photocurrent exceeds a predetermined value. 18. or output a position signal V proportional to the center of gravity position X of the element where the photocurrent exceeds a predetermined value. Output as ut. When the alcohol content in the fuel decreases, the refractive index Nf of the fuel increases, so the total reflection angle ψ also becomes a dog, and the photodiode l element 5 can receive the emitted light from the light emitting element 3.
a corresponds to an elongated light guide with a uniform inclination angle θ of R
Only the elements on the side are used, and when the element number j or center of gravity position X for which the photocurrent exceeds a predetermined value is large, ζ output ■. at
will rise. On the other hand, if the alcohol content in the fuel increases, the total reflection angle ψ will become smaller, and the light will be received from the smaller-numbered photo-I/dio-I element 5a on the side, and the center of gravity position X will also become smaller. As a result, the output Vout decreases. The detection accuracy of the alcohol content is determined by the number of meters of the elongated light guide 1 and the photodiode element 5a, and can be freely selected depending on the user or the purpose of use. In this configuration, since the Al:Nol content in the fuel is detected based on the light receiving position as well as the light intensity distribution on the photodiode array 5, the temperature of the detection part of the detection device as described in 1. changes due to heat generation of the engine, etc. The alcohol content in the fuel can always be accurately and continuously detected regardless of changes in the amount of light emitted by the light emitting element 3 or the photodiode array. Furthermore, since the alcohol content is detected on the small tangential surface 2 provided midway through the elongated light guide 1, there is an effect that the detection section inserted into the fuel can be miniaturized.

FIG. 3 is a block diagram of another embodiment of the present invention, in which the photoreceptor 5
103 is a charging current amplifying section, 104 is a subtracting section, 105 is an adding section, and 106 is an explanatory diagram of a method of detecting alcohol content. In FIG. 31, the ends 1" 11) of the rn elongated light guides 1 are arranged to fall within the effective light receiving width of the light center of gravity position detection element 5, as in the embodiment shown in FIG. , among the light incident on one end of the m elongated light guides 1 from the light emitting element 3 through the average diffuser 4, the average incident angle θ to the tangential plane 2 that is greater than the total reflection angle ψ at the tangential plane 2 with the fuel is Only what is holding the light beam is totally reflected and propagated to the other end side of the elongated light guide 1, and is incident on the light center of gravity position detection element 5.The light center of gravity position detection element 5 is made of a flat zircon plate as shown in FIG. P layer (resistance layer) on the front, N layer on the back, 1 in the middle
When a light beam 1- is incident, a divided photocurrent iR,il-, which passes through the ten resistance layers from the incident light position and reverses the distance to the electrodes IL, IR, flows to the electrodes IL, IR. I
Extracted from R. The extracted photocurrents iR and iL are input to the detection circuit 10 as shown in FIG. After being calculated, the division unit 106 calculates the position signal X-(L)2)
Output ■ proportional to (III-1-11.,). ,
1 is required. No. 14" Optical guide center, the average angle of incidence θ of all m elongated light guides 1 on the tangential plane 2 is 11. with an alcohol content of 100%. If it is larger than the total reflection angle ψ of +1, the light is propagated to the other end side of all the m elongated light guides 1 and becomes a position signal X-O, and if the alcohol content is low. Since the angle of total reflection ψ is a dog,
The average angle of incidence θj≧ on the tangent plane 2 in the m-tree elongated light guide 1
The light is propagated to the other end only from the N-jth and subsequent ones, which is ψ, so that I R > IL and the position signal X becomes large. Therefore, ζ, the output ■ corresponding to the position signal X. ,,.

is inversely proportional to the alcohol content. Even in such a configuration, since the alcohol content is detected by the light intensity distribution of the light center of gravity position detection element 5, the same effect as the embodiment shown in FIG. 2 can be achieved. There is an advantage that there is no need to arrange an element, and the detection accuracy can be improved by increasing the number of elongated light guides.

FIG. 6 is a cross-sectional perspective view of a detection section of an embodiment of the AlniJol content detection device of the present invention, in which the core of the optical fiber huff 7a forms an elongated light guide with the optical fiber huff; Reference numeral 7b designates an optical fiber huff gland, 8 a support member, 9 a joint portion of the optical fiber huff, 11 a filling member, and 12 an end surface joint portion of the optical fiber huff. In this structure, the end faces of two optical fiber huffs are fused together to form a joint 9, and a core 7a is exposed in a part of the joint 9 to form a plane 2 tangent to the fuel. The optical fiber huffs are attached one by one or as an optical fiber band in advance to the support member 8 whose apex angle increases monotonically along the longitudinal direction, and the ends of the support members 8 on the top side of each optical fiber huff are fused. After forming the joint part 9, the case 6 is placed and filled with the filling member 11, and then the case 6 is gradually polished from the top until it reaches the core 7a of the joint part 9 of the optical fiber huff, so that it does not come in contact with the fuel. A manufacturing method is advantageous in which the plane 2 is formed and thereby the average angle of incidence θ of the light on the tangential plane 2 is varied. Further, the ends of the three light emitting elements of the optical fiber huff are each fused to form an end surface joint 12, so that the light from the light emitting element 3 is efficiently incident.

FIG. 7 is an end perspective view of another detection section according to an embodiment of the present invention, and 13 is a bent arc portion of the optical fiber huff. The top of the support member 8 is formed into a circular arc whose radius monotonically increases along the long-term direction, and after the individual optical fibers 7 or an optical fiber band are closely attached to the top of the arc, the support member 8 is housed in the case 6 and filled with the filling member 11. By gradually polishing from the upper part of the case 6 until reaching the core 7a of the bent circular arc portion 13 of the optical fiber huff to form a tangential plane 2 with the fuel, the average incident angle θ of light to the tangential plane 2 is varied. It can be manufactured using the following method. In such a structure, there is no need to join each optical fiber half at the top end of the support member 8 as in the embodiment shown in FIG. 6, so there is an advantage that the number of manufacturing steps can be reduced and the detection unit can be made inexpensive. be.

In the above embodiment, an optical fiber huff is used as the elongated light guide 1, but it is not limited to an optical fiber, and any elongated light guide that requires a relatively small number of man-hours may be used.

Furthermore, in the above embodiment, a structure is shown in which the ends of a plurality of elongated light guides are bundled and light is emitted from one light emitting element onto the elongated light guide, but a light emitting element is provided corresponding to each elongated light guide. Alternatively, the plurality of elongated light guides may be divided into several sets and a light emitting element may correspond to each set, and the light receiving body may also be C
It will be apparent to those skilled in the art that other optical position sensing elements such as CDs can be used. Furthermore, although the above embodiment describes the detection of alcohol content in fuel,
Needless to say, it can also be applied to measuring the refractive index of other liquids.

〔Effect of the invention〕

As explained above, according to the present invention, a plane tangential to the fuel is formed in the middle of each of the plurality of elongated light guides, and a light emitter is provided on one end face of the elongated light guide, and a light receiver is provided on the other end face of the elongated light guide. By installing a sensor, the detection device can be made smaller, and
Since it can be installed in a pipe near the fuel injection valve, the alcohol content in the fuel injected by the fuel injection valve can be detected continuously without delay. Furthermore, the alcohol content can be effectively detected with high accuracy regardless of temperature changes in the detection device.

[Brief explanation of the drawing]

FIG. 1 is a perspective view of a detection section of an alcohol content detection device according to an embodiment of the present invention, FIG. 2 is an explanatory diagram of a detection method according to the present invention, FIG. 6 is a cross-sectional perspective view of the detection section, and FIG.
The figure is a cross-sectional perspective view of another example of the detection unit, FIG. 8 is a partially cutaway configuration diagram of a fuel control system equipped with a conventional alcohol content detection device, and FIG. 9 is a configuration diagram of a conventional alcohol content detection device. It is. DESCRIPTION OF SYMBOLS 1... Elongated light guide, 2... Tangent plane, 3... Light emitting element, 5... Light receiving element, 7... Optical fiber, 9...
Joint portion: 10...Detection circuit, 13...Bending arc portion. Note that the same reference numerals in the figures indicate the same or equivalent parts. Agent Masuo Oiwa 1: Elongated light guide 2: Tangential plane 3: Light emitting element (light emitter) 5: Photodiode array (light receiver) Figure 3 Figure 2 L-1111~---- −−−−−−−−−111” (
Photoreceptor) Figure 4, Figure 6, Figure 7: Optical fiber, Figure 7, Figure 13: Bent arc section procedure correction form (voluntary) 1. Indication of the case: Japanese Patent Application No. 1984-100484 2, Name of the invention Alcohol content detection device 3, Representative of the person making the amendment Moriya Shiki 5, Subject of the amendment 6, Contents of the amendment (1) Specification page 2, line 19 Indicates 1 of ``,'' indicates ``,
” he corrected. (2) Correct “rotational force” in line 8 of page 3 to “rotation”. (3) On page 6, line 3, "1 light-receiving element" is corrected to "light-emitting element." (4) Add "array" next to "diode" on the second line of page 9. (5) On page 13, line 9, "zircon" is corrected to "silicon." (6) On page 16, line 2, "end face" is corrected to "cross section."that's all

Claims (1)

[Claims] An alcohol content detection device that detects the alcohol content in fuel based on the difference in refractive index between a light guide and the fuel,
A plane tangential to the fuel is formed in a part of the middle of each of the plurality of elongated light guides, the angles between the elongated light guides and the tangent plane are different from each other, and light is projected onto one end surface of the elongated light guide. A light receiver is provided on the other end of the elongated light guide to receive the reflected light on the tangent plane, and the alcohol content in the fuel can be determined by changing the light intensity distribution on the light receiver. An alcohol content detection device characterized by detecting alcohol content.