JPH01274042A - Alcohol content detection device - Google Patents

Abstract

PURPOSE:To enable highly accurate detection of an alcohol content continuously all the time without delay, by forming a fuel refractive index detecting surface in the course of each of a plurality of slender photoconductors while a projector is set on one end face of the photoconductors and a light receiving body on the other end face thereof. CONSTITUTION:Fuel refractive index detecting surfaces 2 supports a plurality of optical fibers 1 in parallel tightly on a support member 7 to be fixed with a filling member. Then, the detecting surface is ground to differential distances from the center in the course thereof so that core surfaces with varied average refractive indexes are exposed to form a contact liquid face with a fuel. The detecting surface 2 is arranged parallel with a fuel passage 8 to minimize a pressure loss of a fuel flow 8a. The fibers 1 are joined together at one end thereof to form a junction section 6 and light in equal quantity is made incident on the optical fibers 1 through a light diffusing member 4 from a light emitting element 3. A light center of gravity detector 5 is disposed on the other end side in such a manner as to hold one end of all the optical fibers within an effective light receiving range and receives totally reflected light on the detecting surface 2. Photocurrent is sent to a detection circuit 10 from electrodes IL and IR corresponding to a quantity of light received from the photo detector 5.

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.

[Conventional technology]

In recent years, in countries such as the United States and Europe, in an effort to reduce oil consumption, fuels containing alcohol mixed with gasoline are being used for automobiles. 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 fuel injection valve actuator is controlled by detecting the alcohol content of the fuel injector, 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 configuration diagram showing a fuel control system equipped with a conventional alcohol content detection device, where A indicates the alcohol content detection device, 20 indicates an engine of an automobile, etc., and 21 indicates a fuel installed in an intake pipe. Injection valve, 22 is a fuel tank, 23 is a fuel pump that sucks up the fuel in the tank 22, 25 is pump 2
26 is a fuel distribution pipe, 27 is a fuel pressure regulator, and 28 is a fuel return pipe connected to this regulator 27, the tip of which reaches into the tank 22. There is.

29 is an air-fuel ratio sensor, 30 is a spark plug, 31 is a sensor 1 for detecting engine rotation, 32 is an intake pressure sensor, 3
3 is a Sursotle valve, 34 is an air cleaner, and 35 is a control device that detects the signal of the alcohol content detection device A, the signal of the air-fuel ratio sensor 29, and the state of the engine M! Signals from the engine rotation sensor 31, intake pressure sensor 32, etc. are input manually, and the fuel injection valve 211, spark plug 30, etc. are driven with a control amount corresponding to the input. When the fuel tank 22 is filled with alcohol mixed fuel, when the engine starts,
The alcohol mixed fuel is pressurized by a fuel pump 23 and guided to an alcohol content detection device A through a fuel supply pipe 24 and a high-pressure filter 25, where the alcohol content is measured. The fuel then flows into the fuel distribution pipe 26 , a portion of which is supplied to the engine through the fuel injection valve 21 , and the rest of the fuel is returned to the fuel tank 22 through the fuel pressure 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 manually to the control device 35, the control device 35 detects the engine rotation sensor 3.
1 and the intake pressure sensor 32, etc., the valve opening time of the fuel 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, The air-fuel ratio is feedback-controlled to a target value corresponding to the engine condition, and the ignition timing of the spark plug 30 is controlled according to the engine condition.

FIG. 9 is a configuration diagram of a conventional alcohol content detection device, in which numeral 37 is a cylindrical transparent body made of optical glass or the like, 9 is a case, and 11 is a cylindrical transparent body 37 and a case 9. 3 is a light emitting element consisting of an LED; 36 is a light receiving element consisting of a photodiode; 8 is a fuel flow path;
a is the fuel flow, 38a is the total reflected light, 38b is the refracted light, 1o
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 light emitted from the light emitting element 3 enters the outer peripheral surface of the cylindrical transparent body 37, that is, the interface with the fuel, but at this time, the refractive index Nf of the fuel and the cylindrical transparent body 37
Due to the difference in refractive index Nd from Since the smaller light 38b is refracted and transmitted into the fuel, the angle of incidence on the boundary surface of the light receiving element 36 is the total reflection angle! Only the light that meets the above requirements is received. When the alcohol content in the fuel changes, the refractive index N' of the fuel changes and the total reflection angle changes, so the amount of light received by the light receiving element 3G changes. This change in the amount of received light is measured by the detection circuit IO. The alcohol content in the fuel can be determined by:

[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 3, the light receiving sensitivity of the light receiving element 36, and the peak sensitivity frequency change depending on the temperature, so detection is caused by engine heat generation and a rise in fuel temperature due to it. When the temperature of the device changes, the amount of light received by the light-receiving element 36 also changes, resulting in a drawback that the alcohol content in the fuel cannot be determined accurately. Further, generally, the refractive index N of the cylindrical transparent body 37 is
Due to the restriction of d, the total reflection angle cannot be made too small, so the cylindrical light-transmitting body 37 cannot be made very short, resulting in a problem that 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 fuel in the fuel flow path 8 and the fuel distribution pipe 26 of the alcohol content detection device A It is expected that there will be a starting mode in which the percentage of alcohol content differs, 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 such conventional problems, and it is possible to continuously and accurately detect the alcohol content of fuel without any delay even when the device temperature changes, and the fuel distribution pipe The purpose of this invention is to obtain a small alcohol content detection device that can be attached to 26 etc.

[Means to solve the problem]

The alcohol content detection device according to the present invention forms a fuel refractive index detection surface in the middle of each of a plurality of elongated light guides whose refractive index increases from the periphery toward the center, and projects a fuel refractive index on one end surface of the elongated light guide. A light body is provided, and a photoreceptor is provided on the other end surface.

[For production]

The alcohol content detection 'A W of the present invention allows light to enter the fuel refractive index sensing surface of the plurality of elongated light guides from a light projector at one end of a plurality of elongated light guides, and detects the fuel refractive index sensing surface. The total reflected light is received by a photoreceptor at the other end of each elongated light guide, and the refractive index of the fuel can be detected from the light intensity distribution on the photoreceptor, thereby making it possible to detect the alcohol content in the fuel.

〔Example〕

An embodiment of the present invention will be described below with reference to the drawings. 1st
1 is a block diagram of the alcohol content detection device according to the present invention, FIG. is an elongated optical guide whose refractive index increases monotonically from the periphery toward the center, and here an example using a graded index optical fiber (hereinafter referred to as optical fiber) is shown. 1a is the core of the optical fiber 1; (b) is a grid, 2 is a fuel refractive index detection surface provided in a part of the body for the elongated light, 3 is a light emitting element made of, for example, an LED, 4 is a light diffuser, and 5 is a photoreceptor; An example using an optical center of gravity position detection element made of a PSD is shown, 6 is the joint of the optical fiber ■, 7 is the support member, 8 is the fuel flow path, 8a is the fuel flow, 9 is the case, IO is the detection circuit, 11 is an at-+ seal, and 12 is a filling member. The fuel refractive index detection surface 2 is constructed by supporting a plurality of optical fibers 1 closely parallel to each other on a support member 7 and fixing them with a filling member 12, so that the midway points are at different distances from the center as shown in FIG. The surfaces of the cores la, which are polished and have different average refractive indexes Nd, are exposed to form surfaces in contact with fuel. Further, the fuel refractive index detection surface 2 is arranged parallel to the fuel flow path 8 so that the pressure of the fuel flow 8a is minimized as shown in FIG. One ends of the plurality of optical fibers 1 are joined to each other to form a joint 6, and the light diffuser 4 is connected to the light emitting element 3.
An equal amount of light is incident on each optical fiber 1 through the optical fiber.

On the other end side of the optical fiber 1, an optical center of gravity position detection element 5 is arranged along the optical fiber 1 so that the entire end of the optical fiber 1 falls within the effective light receiving width. Totally reflected light on the detection surface 2 is received. Photocurrents corresponding to the amount of received light are sent from the optical center of gravity position detection element 5 to the detection circuit 10 via electric poles IL and IR, respectively. Here, it is preferable that the light emitting element 3, the light diffuser 4, and the light center of gravity position detection element 5 be configured to be integrally supported by the support member 7. Case 9 through 11
The case 9 is attached to, for example, a fuel distribution pipe 26.
is sandwiched between the inlet pipe and the fuel distribution pipe 26.

Next, the operation of this embodiment will be explained using FIGS. 4 to 6. FIG. 4 is an explanatory diagram of the operation of one embodiment of the alcohol content detection device of the present invention, FIG. 5 is an explanatory diagram of the optical center of gravity position detection element 5, and FIG. This is an explanatory diagram of the change in the distribution of the amount of received light with respect to the alcohol content on the optical center of gravity position detection element 5 in the example, in which lot is a light emitting element drive section, 102 is a photocurrent amplification section, 103 is a subtraction section, 104 is an addition section, 105 is a subtraction unit. In FIG. 4, the light emitting element 3 is driven by the light emitting element driving unit 101 to emit light, and the emitted light passes through the light diffuser 4 and is connected to N = rn optical fibers l.
Of these, the N-1st and jth optical fibers li and lj, whose average refractive indexes at the refractive index detection surface 2 are Ndi and Ndj, respectively, are shown here. Since the refractive index detection surface 2 of the optical fiber 1j is closer to the fiber center, Ndi < Ndj.

As mentioned above in the conventional example, if the refractive index of the fuel that changes depending on the alcohol content is Nf, the critical incidence angle type -arc 5IN in which the incident light is totally reflected on the refractive index detection surface 2 is used.
(Nf/Nd), so the optical fiber 14. lj
Let Ai and 'Pj be the critical incident angles for Nd
i < Ndj J: Riko i > Koj. Incident angle θ
- Instep.

The light incident on the refractive index detection surface 2 is totally reflected in the optical fiber <14 and propagates to the other end of the fiber, but in the optical fiber 11 it is refracted at the refraction angle The amount of light that propagates is significantly smaller than that of the optical fiber 1j. The difference in the amount of light propagating to the other end of the optical fiber 1 forms a light amount distribution on the light center of gravity position detection element 5, and this light amount distribution is caused by a change in the critical angle of incidence due to a change in the refractive index Nf of the fuel. According to Fig. 6 (a) for the alcohol content,
l, (varies as shown in bl) The optical center of gravity position detection element 5, as shown in FIG. No. 3
When a light spot is incident, divided photocurrents iR, iL are extracted from the electrodes IL, IR from the position of the incident light through the resistive layer and inversely proportional to the distance to the electrodes rL, IR. The extracted photocurrents iR and iL are input to the detection circuit IO as shown in FIG.
After the subtraction unit 103 calculates iR−iL and the addition unit 104 calculates iR+iL, the division unit 105 calculates the position signal X = (L/2) X (iRiL) /
(The output output proportional to iR+iL> is obtained. L is the effective light receiving width of the light center of gravity position detection element 5.
As shown in the figure fat, if the average incidence angle θ at the refractive index detection surface 2 is larger than the critical incidence angle type for m optical fibers l when the alcohol content is 100%, then m optical fibers 1 The light is totally reflected to the other end side of the light center of gravity, and the light intensity distribution on the light center of gravity position detection element 5 becomes approximately --like, iR and iL are approximately the same, and the position signal X takes a value close to 0. As the alcohol content decreases, the refractive index Nf increases,
Since the critical incidence angle type in all the optical fibers 1 becomes large, the average refractive index Nd at the refractive index sensing surface 2 among the rn optical fibers 1 is increased in order from the smallest. Reflection no longer occurs, the light is no longer propagated to the other end of the fiber, the light amount distribution is biased toward the electrode IR side, and becomes IL/IR, and the position signal X becomes large. Therefore, the position signal
The corresponding output Vout will be inversely proportional to the alcohol content. Here, the detection accuracy of the alcohol content rate is determined by the number of meters of optical fiber 1, and the user can freely select it depending on the purpose of use. In this configuration, since the alcohol content in the fuel is detected by the light receiving position on the light center of gravity position detection element 5, that is, the light amount distribution, the temperature of the detection part of the detection device changes due to heat generation of the engine, etc., and the light emitting element 3 Even if the amount of light emitted by the sensor and the light receiving sensitivity of the light center of gravity position detection element 5 change, the alcohol content in the fuel can always be accurately and continuously detected regardless of changes in the temperature of the detection section.

In addition, since the detection of alcohol content is performed by a minute refractive index detection surface 2 provided midway through the optical fiber 1,
This has the effect that the detection section inserted into the fuel can be made smaller.

FIG. 7 is a sectional view showing another embodiment of the invention,
After a plurality of optical fibers 1 are tightly supported on the surface of a hollow plate-shaped support member 7 whose tips have a curved surface shape, they are fixed with a filling member 12, and a bending member 1, which is a part of the optical fibers 1 in contact with fuel, is placed in the middle of the optical fibers 1. This embodiment shows an example in which refractive index sensing surfaces 2 are provided at two locations on the front and back sides of the support member 7.

In such a configuration, the ends of the optical fibers 1 can be placed on the same side, and the light emitting element 3, the photoreceptor 5, etc. can be placed and supported on the same side, so that, for example, the light emitting element 3, the photoreceptor 5, etc. The detection unit held integrally can be inserted and installed into the fuel flow path 8 such as the fuel distribution pipe 26 via the fuel seal 11, so there is an advantage that the degree of freedom in installation is increased and the installation is easy. . In addition, by providing multiple refractive index detection surfaces 2, the alcohol content of the fuel in the fuel flow path 8 can be detected more evenly, and the amount of light that contributes to total reflection in the incident light can be increased. It can also be expected that the detection accuracy of the light amount distribution on the body 5 can be improved.

In the above embodiment, a graded index type optical fiber is used as the elongated light guide I. However, the refractive index becomes monotonous from the periphery toward the center at least in the vicinity of the refractive index detection surface, not limited to the above optical fiber. An increasing number of elongated light guides is sufficient. 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 is associated with each set.Furthermore, the photoreceptor may be provided with a light receiving element such as a photodiode corresponding to each of the elongated light guides. It is clear to those skilled in the art that the light amount distribution may be calculated from the output of each light receiving element, or that other optical position detection elements such as a CCD may be used. Furthermore, although the above embodiments described detection of alcohol content in fuel, it goes without saying that the present invention 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 fuel refractive index detection surface is formed on a plurality of four elongated light beams whose refractive index increases from the periphery toward the center, and a light projector is provided on one end surface of the light guide. ,
Since a photoreceptor is provided on the other end surface to detect the alcohol content in the fuel 4, the detection device can be made smaller.
Furthermore, since the detection device is provided in the conduit near the fuel injection valve, the alcohol content in the fuel injected by the injection valve can always be detected continuously without delay. Furthermore, the alcohol content can be detected with high accuracy regardless of temperature changes in the detection device.

[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 a sectional view taken along the line n-■ in FIG. 1, FIG. 3 is an explanatory diagram of the fuel refractive index detection surface, and FIG. The figure is an explanatory diagram of the operation of the alcohol content detection device, FIG. 5 is an explanatory diagram of the optical center of gravity position detection element, and FIG. 6(a). (bl is an explanatory diagram of changes in the distribution of received light amount with respect to alcohol content, FIG. 7 is a sectional view of an alcohol content detection device according to another embodiment of the present invention, and FIG. 8 is a diagram showing a conventional alcohol content detection device) Fig. 9 is a cross-sectional view of a conventional alcohol content detection device. l... optical fiber, la... core, 2... refractive index detection surface, 3... ...Light emitting element, 5... Optical center of gravity position detection element, 10... Detection circuit. In the figures, the same reference numerals indicate the same or corresponding parts. Agent Masu Oiwa 9 - ~ rnlO ( 2 Fig. 3 1σ:] A Fig. 4 Fig. 5 Fig. 6 rL: IRIL < IRIL < IR Fig. 7 Procedures Amendment (Spontaneous request by the Commissioner of the Patent Office)
・Indication of incident 0 Japanese Patent Application No. 104705 2, Name of the invention Alcohol content detection device 3, Representative of the person making the amendment Moriya Shiki Mitsubishi Electric Corporation 5, Claims of the specification to be amended and Detailed explanation of the invention 6,
Contents of the amendment (1) The scope of claims is corrected as shown in the attached sheet. (2) "Increase in F" on page 7, line 15 of the specification is corrected to "change." (3) "Increase" on page 15, line 6 of the same specification. " is corrected as "change." (4) "Increase J" in line 2 of page 1G of the same page is corrected as "change." 7. Amendment of list of attached documents Claims: Single kite Above patent claims: Light guide An alcohol content detection device that detects the alcohol content in the fuel based on the difference in refractive index between the alcohol content and the fuel,
A fuel refractive index sensing surface is formed in a part of the middle of each of the plurality of elongated light guides, a light projecting body is provided on one end face of the elongated light guide to make the light incident on the fuel refractive index sensing face, and a light projector is provided on the other end face. In a device configured to provide a photoreceptor to receive reflected light from the surface A of the surface of the workpiece and detect the real alcohol content based on a change in the light intensity distribution on the photoreceptor, a plurality of elongated light guides detect light from the surroundings. The refractive index increases toward the center! The Il long light guide is characterized in that a part of the middle of each of the guides is removed and formed to have a different thickness so that the average refractive index of the elongate light guide at the fuel refractive index detection surface is different. Alcohol content detection device.

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 fuel refractive index sensing surface is formed in a part of the middle of each of the plurality of elongated light guides, a light projecting body is provided on one end face of the elongated light guide to make the light incident on the fuel refractive index sensing face, and a light projector is provided on the other end face. In a device configured to provide a photoreceptor to receive reflected light on a tangential plane and detect the real alcohol content based on a change in the light intensity distribution on the photoreceptor, a plurality of elongated light guides are arranged from the periphery toward the center. The elongated light guide is formed by removing a portion of the middle of each light guide with a different thickness so that the average refractive index of the elongate light guide at the fuel refractive index sensing surface is different. An alcohol content detection device characterized by: