JPH05288707A - Capacitance type sensor and discriminating device of properties of fuel using the sensor - Google Patents

Abstract

PURPOSE:To detect accurately the concentration of alcohol of alcohol-blended gasoline or a change in the properties of the gasoline due to an additive mixed in the gasoline. CONSTITUTION:A capacitance type sensor 15 of which a detection voltage V changes corresponding to a relative dielectric constant determined in accordance with the properties of gasoline is constructed so that it has a first electrode 22 and a second electrode 23 in a pair which are disposed in the direction perpendicular to a fuel flow passage 21 respectively. High-frequency voltages VH1 and VH2 of which peak values V01 and V02 are different are impressed on the first and second electrodes 22 and 23 from oscillators 24 and 25 respectively and thereby an electric field in the fuel flow passage 21 is made a vectorial electric field. According to this constitution, alcohol-blended gasoline G in the fuel flow passage 21 generates dielectric polarization corresponding to a field strength and detection voltages V1 and V2 corresponding to the relative dielectric constant of the alcohol-blended gasoline G are detected from the electrodes 22 and 23 respectively.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a capacitance type sensor for measuring the relative permittivity of a mixed fuel of methanol and ethanol or a fuel mixed with an additive, and a fuel injection control of an engine using these fuels. The present invention relates to a fuel property determination device applied to a device or the like.

[0002]

2. Description of the Related Art In recent years, due to demands for environmental protection, energy saving, etc., attention has been paid to an alcohol-mixed fuel prepared by mixing alcohol such as methanol with gasoline as fuel for automobiles. However, since the theoretical air-fuel ratio of this alcohol-mixed fuel differs depending on the alcohol concentration, it is necessary to install an alcohol concentration measuring device in the fuel pipe to measure the alcohol concentration in the fuel and adjust the fuel injection amount accordingly.

The air-fuel ratio A / F of genuine gasoline is 1
Although it is 4.7, it is necessary to control the air-fuel ratio A / F to be 6.5 when methanol having an alcohol concentration of 100% is used. The air-fuel ratio A / F will differ about twice.

Therefore, when alcohol mixed fuel is used, an alcohol concentration measuring device called an alcohol sensor is provided, an output voltage corresponding to the alcohol concentration is generated, and the fuel injection amount is calculated based on the output voltage value. I'm doing it.

As this type of alcohol concentration measuring device, a capacitance type alcohol concentration measuring device for detecting the alcohol concentration from the dielectric constants of gasoline and alcohol is known.

[0006] However, in the above-mentioned prior art, when the alcohol mixed in gasoline is a single alcohol, although excellent detection is possible, the alcohol mixed in gasoline is typically ethanol, Two types, methanol, are conceivable. There are cases where they are mixed individually and cases where they are mixed and mixed. Since ethanol and methanol have different components and relative dielectric constants (ethanol 32, ethanol 24, gasoline 2), when mixed and mixed, it is necessary to individually detect the ethanol concentration and the methanol concentration. However, in the conventional alcohol concentration measuring device,
The mixing ratio of ethanol and methanol cannot be detected.

Even when ethanol or methanol is mixed alone, the same alcohol is not always mixed, and ethanol and methanol have different influences on the capacitance due to the difference in relative dielectric constant.
A single alcohol concentration measuring device cannot handle it.

Further, when a mixed gasoline in which two kinds of alcohol may be mixed is used in an engine of an automobile or the like, it is impossible to perform appropriate fuel injection amount control and ignition timing control for the engine. was there.

Therefore, in order to solve these problems, the present applicant has a possibility that two kinds of alcohol may be mixed in according to Japanese Patent Application No. 3-290941 (hereinafter referred to as "first prior art"). An application has been filed for a fuel property discriminating device capable of individually detecting the alcohol concentration of each alcohol-mixed fuel and performing appropriate fuel injection amount control and ignition timing control of the engine.

The fuel property discriminating apparatus according to the first prior art is constructed by an electrostatic device provided in one alcohol, another alcohol, or an alcohol mixed fuel in which both one alcohol and another alcohol are mixed. A capacitance sensor, a first capacitance calculation means for calculating a capacitance or a relative dielectric constant based on a detection signal from the capacitance sensor when a first voltage is applied to the capacitance sensor, and the capacitance sensor. Second capacitance calculation means for calculating capacitance or relative permittivity by a detection signal from the capacitance sensor when a second voltage is applied to the capacitance sensor, and one known alcohol and another alcohol And a known one alcohol, which stores a rate of change in capacitance or relative permittivity calculated by the first capacitance calculation means when the mixing ratio of is changed. other Second storage means for storing the rate of change in capacitance or relative permittivity calculated by the second capacitance calculation means when the mixing ratio with rucor is variable, and an unknown alcohol mixture First mixing line calculating means for calculating a capacitance or a relative permittivity of the fuel using the first capacitance calculating means, and calculating a mixing line of one alcohol and another alcohol from the first storage means; A second capacitance calculating means for calculating an electrostatic capacitance or a relative permittivity of an unknown alcohol mixed fuel, and calculating a mixing line of one alcohol and another alcohol from the second storing means. An intersection of the mixing line calculation means and the mixing line by the first and second mixing line calculation means is obtained, and from this intersection, one alcohol concentration, another alcohol concentration or one alcohol and another alcohol in the alcohol mixed fuel is obtained. Consisting of individual concentration calculating means for calculating the individual concentrations of the call.

In another configuration, the first alcohol and the second alcohol having different electrode constants are provided in the alcohol mixed fuel in which one alcohol, another alcohol, or both one alcohol and another alcohol are mixed. A capacitance sensor and the first
When a voltage is applied to the electrostatic capacitance sensor, the first capacitance calculating means for calculating the electrostatic capacitance or the relative permittivity by the detection signal from the electrostatic capacitance sensor, and the voltage to the second electrostatic capacitance sensor. A capacitance value or a relative permittivity is calculated by a detection signal from the capacitance sensor when a voltage is applied.
Ratio of the capacitance or relative dielectric constant calculated by the first capacitance calculating means when the mixing ratio of the known one alcohol and the other alcohol is variable, When the mixing ratio of the known first alcohol and the other known alcohol is variable, the capacitance or relative permittivity calculated by the second capacitance calculator is set. Of the alcohol or the unknown alcohol mixed fuel using the second storage means for storing the rate of change of the alcohol and the first capacity calculation means, and the one alcohol from the first storage means is calculated. A first mixing line calculating means for calculating a mixing line of the other alcohol and a second capacitance calculating means for the unknown alcohol mixed fuel is used to calculate a capacitance or a relative dielectric constant, and the second storage is performed. By means of one alcohol Of the mixed line of the second mixed line calculating means for calculating the mixed line of the alcohol and the mixed line by the first and second mixed line calculating means, and from this intersecting point, one alcohol concentration in the alcohol mixed fuel, etc. And an individual concentration calculating means for calculating the individual concentrations of one alcohol and another alcohol.

On the other hand, genuine gasoline used as a fuel for automobile engines includes light gasoline mainly containing coal hydrogen such as heptane and pentane, and heavy gasoline mainly containing coal hydrogen such as benzene. , Middle grade gasoline located between the heavy and light gasoline. Light gasoline has the property of being easily vaporized,
Heavy gasoline has the property of being difficult to vaporize.

In a gasoline engine used for an automobile engine, ignition timing and the like are usually set to match light gasoline, but recently heavy gasoline has become popular, and the air pollution law has been adopted. Due to reasons such as enforcement of gasoline, heavier gasoline is being used.

However, when heavy gasoline is used as fuel in a gasoline engine which is set to control the ignition timing of the engine by matching with light gasoline, the ignition timing is delayed as compared with light gasoline. As a result, there is a tendency to become lean as a whole, starting performance at low temperature,
There is a problem that driving performance is deteriorated. Further, even when the vehicle is in a running state, when heavy gasoline is used, there is a problem that not only the driving performance such as breathing phenomenon deteriorates but also harmful components in exhaust gas increase due to incomplete combustion.

On the other hand, contrary to the above, when light gasoline is used in a gasoline vehicle that is set to match the heavy gasoline to control the ignition timing and the like, an overall overrich tendency occurs and ignition There is a problem that "smoldering" occurs in the plug.

In addition, commercially available genuine gasoline includes
An alcohol component such as methanol, ethanol, MTBE (methyl tert-butyl ether) may be mixed as an additive. In this way, when the alcohol content is mixed into the genuine gasoline, the dielectric constant is increased by the alcohol content, so that the output voltage is increased according to the mixing ratio of the additive.

However, in a normal gasoline property discriminating apparatus (for example, Japanese Patent Application No. 2-49724), since the output voltage is only compared with a predetermined comparison voltage value, it is possible to accurately determine whether it is light, medium or heavy. There is a problem that it cannot be judged.

Therefore, in order to solve these problems, the applicant of the present invention has an unknown additive in an unknown gasoline according to Japanese Patent Application No. 3-290943 (hereinafter referred to as "second prior art"). Even if it is mixed in a concentration, it is possible to accurately determine the type of gasoline, the type of additive, and the concentration of additive, detect heavy and light substances with high accuracy, and perform appropriate engine control. Applied for a fuel property determination device.

The fuel property discriminating apparatus according to the second prior art has a capacitance sensor provided in gasoline and a capacitance sensor when a first voltage is applied to the capacitance sensor. A first capacitance calculating means for calculating a capacitance or a relative permittivity according to a detection signal from the sensor; and a static capacitance according to a detection signal from the capacitance sensor when a second voltage is applied to the capacitance sensor. A second capacity calculating means for calculating the electric capacity or the relative permittivity, a known type of gasoline,
When the type of additive and the concentration of the additive are made variable,
The type of each gasoline calculated by the first capacitance calculating means with respect to the concentration of the additive, the rate of change in the capacitance or the relative dielectric constant depending on the type of the additive are stored as a plurality of characteristic lines. The first storage means and known types of gasoline,
When the type of additive and the concentration of the additive are made variable,
The type of each gasoline calculated by the second capacitance calculating means with respect to the concentration of the additive, and the rate of change in the capacitance or the relative dielectric constant depending on the type of the additive are stored as a plurality of characteristic lines. The second storage means and the first capacity calculating means for the unknown gasoline are used to calculate the electrostatic capacity or the relative dielectric constant, and a plurality of gasoline types are calculated from the respective characteristic lines of the first storage means. , The first concentration calculating means for calculating the concentration of the additive with respect to the kind of the additive, and the second capacity calculating means for the unknown gasoline are used to calculate the electrostatic capacity or the relative dielectric constant, Second concentration calculation means for calculating the concentration of the additive for a plurality of types of gasoline and types of additives from each characteristic line of the storage means;
The gasoline type, the additive type, and the concentration of the additive can be calculated by selecting the part that is the same among the multiple gasoline types and the additive concentrations for the additive types calculated by the concentration calculating means. And a gasoline selection means for calculating.

[0020]

However, in the above-mentioned first and second prior arts, two capacitance sensors having different electrode constants are provided, or one capacitance sensor is used. There is an unsolved problem that two voltage applying means for applying different voltages are provided and the respective voltage applying means are switched, which complicates the structure.

Further, when two capacitance sensors are provided, two must be provided in the middle of the fuel pipe, and there is an unsolved problem that the number of connecting portions increases and a fuel leakage accident easily occurs.

The present invention has been made in view of the above-mentioned unsolved problems of the prior art, and provides a capacitance sensor which can be formed compactly, and detects the concentration of each alcohol in the fuel or the property of the fuel. It is an object of the present invention to provide a fuel property determination device that can be accurately determined.

[0023]

In order to solve the above problems, a capacitance type sensor adopted by the present invention has a fuel inlet and an outlet, and fuel is directed from the inlet to the outlet. And a pair of first electrodes provided separately on the side surface of the fuel flow path and opposed to each other through the flowing fuel, and the first electrode separated from the side surface of the fuel flow path. It is composed of a pair of second electrodes which are provided so as to be orthogonal to each other and which are opposed to each other with the circulating fuel therebetween.

Further, the fuel flow passage is formed in a straight line so that the fuel flowing from the inlet flows in the axial direction and flows out from the outlet, and the first and second electrodes are connected to the fuel flow passage. The electrostatic capacitance type sensor according to claim 1, wherein the electrodes are arranged as parallel plate type electrodes so as to be orthogonal to each other.

Further, the fuel flow passage is formed in an annular shape so that the fuel introduced from the inflow port is branched and circulates in an arc shape, merges in front of the outflow port and flows out. Two electrodes are formed so that one electrode is formed of a pair of annular plates along the fuel flow passage having an annular shape and the other electrode is formed as a coaxial cylindrical electrode so as to be orthogonal to the fuel flow passage. The capacitive sensor according to claim 1, wherein

On the other hand, the fuel inlet and outlet are formed, the fuel passage through which the fuel flows from the inlet to the outlet, and the fuel that is provided separately from the side surface of the fuel passage and flows. A pair of first electrodes opposed to each other via a side surface of the fuel flow path, and is provided so as to be orthogonal to the first electrode,
A pair of second electrodes facing each other through the flowing fuel, first and second voltage applying means for applying a high-frequency voltage to the first and second electrodes, and the first and second voltage applying means for applying the first and second voltage electrodes, respectively. When a high-frequency voltage is applied to the second electrode, a detection processing unit that detects an electric signal corresponding to the property of the fuel from between at least one of the first and second electrodes is used. Property determination device.

The first and second voltage applying means apply different high frequency voltages to the first and second electrodes, respectively, and the detection processing means corresponds to the property of the fuel from between the first and second electrodes. The fuel property determining device according to claim 4, wherein the fuel property determining device detects the electric signal.

Further, an equal high frequency voltage is applied to the first and second electrodes from either the first or second voltage applying means, while the first and second electrodes are first and second electrodes applied to the first and second electrodes. A second high-frequency voltage is applied from each of the second voltage applying means, and the detection processing means detects an electric signal according to the property of the fuel from between one of the first and second electrodes. 4. The fuel property determination device described in 4.

Furthermore, the electrode constants of the first and second electrodes are formed to be different, and the same high-frequency voltage is applied to the first and second electrodes from either the first or second voltage applying means. 5. The fuel property discriminating apparatus according to claim 4, wherein the detection processing means detects an electric signal corresponding to the property of the fuel from between the first and second electrodes.

[0030]

In the capacitance type sensor having the above structure,
By applying a high frequency voltage to each of the first electrode and the second electrode, the electric field applied to the fuel flowing through the fuel flow path becomes a vector electric field having a magnitude and a direction. Dielectric polarization with respect to the permittivity of the fuel is generated depending on the size and direction.

On the other hand, in the fuel property discriminating device having the above-mentioned structure, the high-frequency voltage is applied to the first electrode and the second electrode constituting the electrostatic capacity type sensor by the first and second voltage applying means to detect the high-frequency voltage. The processing means detects two dielectric polarizations with respect to the permittivity of the fuel as electric signals, and determines the property of the fuel based on each electric signal.

[0032]

Embodiments of the present invention will be described below with reference to FIGS. 1 to 27.

First, the alcohol concentration measurement according to the first embodiment of the present invention will be described as an example with reference to FIGS. 1 to 11.

In the figure, reference numeral 1 indicates, for example, a four-cylinder engine (only one cylinder is shown). The engine 1 is a cylinder 1A,
A cylinder head 1B mounted on the cylinder 1A,
It is roughly configured of a piston 1C that reciprocates in the cylinder 1A. Reference numeral 2 indicates an ignition plug (only one is shown) provided on the cylinder head 1B located above each cylinder 1A. The ignition plug 2 is a cylinder when an ignition signal is output from a control unit 29 described later. It is designed to burn (explode) the air-fuel mixture in 1A.

Reference numeral 3 denotes an intake manifold provided on the intake side of the cylinder head 1B of the engine 1 with a base end side serving as a branch pipe. An intake filter 4 is provided on the front end side of the intake manifold 3 and in the middle thereof. An air flow meter 5 for measuring the amount of intake air, a throttle valve 7 provided with a throttle valve switch 6 and the like are provided, and an injection valve 8 is provided near the cylinder head 1B. The injection valve 8 is a control unit. The alcohol mixed gasoline G is injected into the engine 1 by the injection signal from 29.

Reference numeral 9 indicates a fuel tank for storing the alcohol-mixed gasoline G therein, and an in-tank type fuel pump 10 is provided in the fuel tank 9. Reference numeral 11 denotes a fuel pipe, one end of the fuel pipe 11 is connected to the discharge side of the fuel pump 10 through the fuel filter 12, and the other end is connected to the injection valve 8 and the inflow side of the pressure regulator 13. The outflow side of 13 is connected to the fuel tank 9 via a return pipe 14.

Reference numeral 15 denotes a capacitance type sensor according to the present embodiment provided in the middle of the fuel pipe 11. The capacitance type sensor 15 is connected to a control unit 29 via a detection processing circuit 16 which will be described later. The change in the relative permittivity due to the property state of the alcohol mixed gasoline G flowing in the fuel pipe 11 is detected.

Here, as shown in FIG. 2, the alcohol concentration measuring device as the fuel property determining device according to the present embodiment has a capacitance type sensor 15 and the capacitance type sensor 15.
A high-frequency voltage VH1 is applied to a first electrode 22 which will be described later and is disposed inside.
Connected to the first and second electrodes 22 and 23 and a second oscillator 25 for applying a high frequency voltage VH2 to the second electrode 23, and a detection voltage V1 as a detection signal. V2 is differentiated by differentiating circuits 26, 26, and each of the differentiating circuits 26 and the first and second oscillators 2
The detection processing circuit 16 is composed of 4, 25. Then, the signal from each of the differentiating circuits 26 is input to the control unit 29, and the control unit 29 performs the processing as described in the first prior art, so that the gasoline, ethanol, It is designed to detect each concentration of methanol.

Next, the configuration of the capacitance type sensor 15 of the alcohol concentration measuring device will be described with reference to FIGS.

Reference numeral 17 denotes a casing which is made of a metal material and constitutes the main body of the capacitance type sensor 15. The casing 17 has an outlet pipe 19 having a fuel outlet 19A.
Bottomed cylindrical casing body 17A having a bottom protruding from
And an inflow pipe 18 having a fuel inflow port 18A, and a lid 17B projecting from the inflow pipe 18, and the inflow pipe 18 and the outflow pipe 19 are connected to the fuel pipe 11, respectively, so that the alcohol mixed gasoline G is discharged. Capacitance sensor 15
Circulate inside.

Reference numeral 20 denotes an insulating case which is provided in the casing 17 and is made of an insulating resin material such as polytetrafluoroethylene. The insulating case 20 has five resin layers on each inner peripheral surface of the casing body 17A. By attaching a plate, the case main body 20B, which has a square opening 20A, and the lid 17B, are attached to the lid 17B to close the opening 20A in a liquid-tight manner.
0C, and an inflow hole 20D communicating with the inflow port 18A of the inflow pipe 18 and the outflow pipe 19 and the outflow port 19A at the bottom of the case lid 20C and the case body 20B.
And an outflow hole 20E is provided.

Reference numeral 21 denotes a fuel flow path formed in the insulating case 20 in the axial direction. The fuel flow path 21 receives the alcohol mixed gasoline G flowing from the inflow port 18A of the inflow pipe 18 through the inflow hole 20D. It flows into the insulating case 20 and flows out from the outlet 19A of the outlet pipe 19 through the outlet hole 20E.

Reference numeral 22 denotes a first electrode according to the present embodiment (see FIG. 2), and 22A and 22B are attached so as to sandwich the fuel flow passage 21 on one of both sides of the inner peripheral surface of the case body 20B. The electrode plate that is formed into the first electrode 22 is the electrode plate 2
2A serves as an input side electrode plate and is connected to the first oscillator 24 via a lead wire 22C, and the electrode plate 22B serves as an output side electrode and is connected to one differentiating circuit 26 via a lead wire 22D.

Reference numeral 23 denotes a second electrode according to the present embodiment (see FIG. 2), and 23A and 23B are arranged such that the fuel flow passage 21 is sandwiched between the other side surfaces of the inner peripheral surface of the case body 20B. The second electrode 2 is attached orthogonally to the first electrode 22.
With the electrode plate forming 3, the electrode plate 23A becomes the input side electrode,
Connected to the second oscillator 25 via a lead wire 23C,
The electrode plate 23B serves as an output side electrode and is connected to the other differentiating circuit 26 via the lead wire 23D.

The electrode plates 22A and 22B, 23A and 23B of the first electrode 22 and the second electrode 23 are formed to have the same distance d and the same surface area S, as shown in FIG. First and second electrodes 2 respectively
Reference numerals 2 and 23 are formed as parallel plate electrodes and have an electrode constant K (K = S / d). Further, the fuel flow path 21 has a square shape.

Reference numeral 24 denotes a first oscillator as a first voltage applying means, and the first oscillator 24 has a built-in attenuator for applying a high frequency voltage VH1 (peak value V01, frequency f) to the first electrode 22. Apply.

Reference numeral 25 denotes a second oscillator as a second voltage applying means, and the second oscillator 25 has a built-in attenuator for applying a high frequency voltage VH2 (peak value V02, frequency f) to the second electrode 23. Apply. In addition, each oscillator 2
The relationship between the peak values of the high frequency voltages VH1 and VH2 of 4, 25 is V01
Adjusted by each attenuator to be> V02.

Here, in the capacitance type sensor 15,
As shown in FIG. 2, since the high-frequency voltages VH1 and VH2 applied have different peak values, the electric fields from the electrodes 22 and 23 acting on the fuel flow passage 21 become vectorial electric fields, and the electric fields are directed in the direction of this electric field. On the other hand, the fuel flow path 21 between the electrodes 22 and 23
The polarization directions of the fuel molecules inside are aligned, and the molecules extend even with respect to the strength of the electric field, causing dielectric polarization in the electric field direction.
Then, the changes in the dielectric polarization are detected from the electrodes 22 and 23 as two detection voltages V1 and V2 corresponding to the relative permittivity of the alcohol mixed gasoline G.

Reference numerals 26 and 26 denote differentiating circuits connected to the output side electrodes of the first electrode 22 and the second electrode 23 via lead wires 22D and 23D, respectively.
Is composed of an operational amplifier 27 and a negative feedback resistor 28 connected between the output terminal and the inverting terminal of the operational amplifier 27, and the non-inverting terminal of the operational amplifier 27 is connected to the ground.

Reference numeral 29 represents a control unit according to this embodiment, and the control unit 29 is, for example, an RA.
The control unit 29 is composed of an M, a ROM and the like as a microcomputer.
0, a processing circuit 31, and a storage circuit 32. The input side of the input / output control circuit 30 has a detection voltage V1 from the first electrode 22 and the second electrode 23 of the capacitance type sensor 15, V2 is connected so as to be input through each differentiating circuit 26. Further, in the storage area 32A of the storage circuit 32, in addition to the alcohol concentration detection processing program shown in FIGS. 8 and 9, a fuel injection calculation program, an ignition timing control program (neither is shown), etc. are incorporated. .. Further, a characteristic map I shown in FIG. 6 and a characteristic map II shown in FIG. 7 are stored in the storage area 32A.

In FIG. 1, the input side of the input / output control circuit 30 of the control unit 29 includes the air flow meter 5, the throttle valve switch 6, the crank angle sensor for detecting the engine speed, the engine switch, and the like. In addition, various sensors such as a water temperature sensor and an oxygen sensor are connected, an ignition plug 2 and an injection valve 8 are connected on the output side, and a fuel injection calculation program and an ignition timing control program (both are shown in FIG. (Not shown) is used for control processing.

Here, the characteristic map I indicates various known alcohols in which the concentrations of gasoline and ethanol (for example, 0%, 15%, ...) And the concentrations of gasoline and methanol (for example, 0%, 15%, ...) Are fixed. Capacitive sensor 1 for mixed gasoline using the alcohol concentration measuring device of the present embodiment
No. 5 is the detection voltage V1 from the first electrode 22, the horizontal axis is the ethanol concentration E, and the vertical axis is the detection voltage V1.
Is a graph showing the change in the methanol concentration M with reference to.

On the other hand, the characteristic map II shows various known alcohol mixtures in which the concentrations of gasoline and ethanol (for example, 0%, 15%, ...) And the concentrations of gasoline and methanol (for example, 0%, 15%, ...) Are fixed. Capacitance sensor 15 for gasoline is measured by the alcohol concentration measuring device of the present embodiment.
It is created by the detection voltage V2 from the second electrode 23 of the above, and is a graph showing the change of the methanol concentration M with the ethanol concentration E on the horizontal axis and the detection voltage V2 on the vertical axis.

Then, the storage area 32A of the storage circuit 32
The storage of the characteristic map I in the first prior art
The storage of the characteristic map II in the storage area 32A of the storage circuit 32 serves as the second storage according to the first prior art.

Next, the detection process for detecting the unknown methanol concentration MX and the unknown ethanol concentration EX in the unknown alcohol-blended gasoline G will be described with reference to the programs shown in FIGS. 8 and 9.

For convenience, the unknown methanol concentration and ethanol concentration are defined as methanol mixture concentration M and ethanol mixture concentration E, and the known methanol concentration M and ethanol concentration E and the methanol concentration MX and ethanol concentration in the unknown alcohol-mixed gasoline G are shown. Try to distinguish it from EX.

First, in step 1, the capacitance type sensor 15
The detection voltage V1X corresponding to the relative permittivity of the alcohol-mixed gasoline G flowing into the fuel passage 21 inside the first electrode 22
, And the detection voltage V2X is read from the second electrode 23.

In step 2, the ethanol mixture concentrations E10, E11, ... Corresponding to the methanol mixture concentrations M0, M1, ... At the detection voltage V1X are calculated from the characteristic map I (see the characteristic map I in FIG. 6). Concentration M0
, M1, ... And ethanol mixed concentrations E10, E11, ... are stored in the storage area 32A of the storage circuit 32.

In step 3, the ethanol mixture concentrations E20, E21, ... Corresponding to the methanol mixture concentrations M0, M1, ... At the detection voltage V2X are calculated from the characteristic map II (see the characteristic map II in FIG. 7). Concentration M0
, M1, ... And the ethanol mixed concentrations E20, E21, ... are stored in the storage area 32A of the storage circuit 32.

In step 4, as shown in FIG. 10, the ethanol mixture concentrations E10, E11, ... Corresponding to the methanol mixture concentrations M0, M1, ... Detected corresponding to the detection voltage V1X stored in the storage area 32A are obtained. A mixing line L1 is calculated on a graph in which the horizontal axis represents the methanol mixing concentration M and the vertical axis represents the ethanol mixing concentration E (first mixing line calculating means according to the first prior art). 10 shows the ethanol mixture concentrations E20, E21, ... Corresponding to the methanol mixture concentrations M0, M1, ... Detected corresponding to the detection voltage V2X.
Calculate the mixed line L2 above (the second according to the first prior art)
Mixed line calculation means). Then, the calculated mixed line L
The intersection of 1 and L2 is detected, and the unknown ethanol concentration EX,
The methanol concentration MX is calculated (individual concentration calculating means according to the first prior art).

Then, in step 5, the fuel injection amount and the ignition timing are controlled based on the ethanol concentration EX and the methanol concentration MX of the unknown alcohol mixed gasoline G detected in step 4, and the spark plug 2 and the injection valve 8 are controlled.
Output a signal to.

As described above, in the alcohol concentration measuring apparatus according to the present embodiment, the capacitance type sensor 15 for detecting the relative permittivity of the alcohol mixed gasoline G is arranged in the direction orthogonal to the fuel flow passage 21. First electrode 2
2, a configuration having a second electrode 23, the first electrode 22,
High frequency voltages VH1 and VH2 having different peak values V01 and V02 are applied to the second electrode 23 from the oscillators 24 and 25, respectively.
By making the electric field in the fuel flow path 21 a vector electric field having the magnitude and direction, the alcohol mixed gasoline G in the fuel flow path 21 generates a dielectric polarization corresponding to the electric field strength, and Detection voltage V1 from the electrode 22 and the second electrode 23 corresponding to the relative permittivity of alcohol mixed gasoline G
, V2 are respectively detected.

Even when ethanol and methanol are mixed in the alcohol mixed gasoline G by the detection voltages V1 and V2, the ethanol concentration EX and the methanol concentration MX can be reliably detected. Further, even when ethanol or methanol alone is mixed in gasoline, the respective ethanol concentration EX or methanol concentration MX can be accurately detected by this alcohol concentration measuring device.

Therefore, it is possible to accurately detect any mixture concentration of the alcohol-blended gasoline G of ethanol and methanol, to properly control the appropriate fuel injection amount and ignition timing, and to improve the driving performance of the vehicle. ..

Further, unlike the first prior art, it is not necessary to provide two capacitance sensors having different electrode constants, and the capacitance type sensor 1 having the first electrode 22 and the second electrode 23 is provided.
Since it is only necessary to provide 5 in the middle of the fuel pipe 11,
The connecting portion with the fuel pipe 11 can be reduced,
It is possible to reliably prevent fuel leakage accidents and improve safety.

Further, in the first prior art, when one capacitance sensor is provided, two voltage applying means for applying different voltages are provided and the voltage applying means are switched. However, in this embodiment, it is possible to simplify the structure without the need for switching, shorten the switching time, and perform quick detection.

In the first embodiment, the detection signals corresponding to the relative permittivity of the alcohol mixed gasoline G from the first electrode 22 and the second electrode 23 of the capacitance type sensor 15 are detected voltages V1 and V2. However, the present invention is not limited to this, and as shown in FIG. 11, the high frequency voltages VH1 and VH2 from the oscillators 24 and 25 are input as reference signals to the control unit 29 via the reference signal lines 33 and 34. The reference signal (high-frequency voltage VH1, VH2) and the detection voltages V1, V2 may be used to detect the capacitance between the first electrode 22 and the second electrode 23.

Next, a second embodiment of the present invention will be described with reference to FIG. 12. The feature of this embodiment is that the electrode constants of the electrodes of the capacitance type sensor are made different, and the respective electrodes are made different. A common high frequency voltage is applied to each of the electrodes to derive a detection voltage from each of the electrodes. The same components as those in the first embodiment described above are designated by the same reference numerals, and the description thereof will be omitted.

In FIG. 12, reference numeral 35 denotes a capacitance type sensor according to this embodiment, which is provided in the middle of the fuel pipe 11 and is connected to the control unit 29 via the detection processing circuit 16. Has been done.

Reference numeral 36 denotes a fuel flow path through which the alcohol mixed gasoline G flowing in the fuel pipe 11 flows, 37 denotes the first electrode according to the present embodiment, and 37A and 37B are attached so as to sandwich one of the fuel flow paths 36. The electrode plate forming the first electrode 37. The electrode plate 37A serves as the input side electrode plate and is connected to the first oscillator 24 via the lead wire 37C, and the electrode plate 37B serves as the output side electrode plate. It is connected to one of the differentiating circuits 26 via a line 37D.

Reference numeral 38 denotes a second electrode according to this embodiment, 3
Reference numerals 8A and 38B denote electrode plates that sandwich one side of the fuel flow path 36 and are bonded orthogonally to the first electrode 37 to form the second electrode 38. The electrode plate 38A serves as an input side electrode plate.
Connected to the first oscillator 24 via a lead wire 38C,
The electrode plate 38B serves as an output-side electrode plate and is connected to one of the differentiating circuits 26 via a lead wire 38D.

Incidentally, the capacitance type sensor 3 according to the present embodiment.
5, the electrode plates 37A, 3A of the first electrode 37 are
7B is the area S1 and the separation distances d1 and the electrode constant K1
(K1 = S1 / d1), the electrode plates 38A and 38B of the second electrode 38 have an area S2 (S2> S1) and a separation distance d2 (d2 <d1), and the electrode constant K2 (K2 = S2).
/ D2). Thereby, the electrode constants K1 and K of the first electrode 37 and the second electrode 38 of the capacitance type sensor 35 are set.
2 is configured as a parallel plate type electrode having different values.

Therefore, in the present embodiment, the first electrode 3
7 between the electrode plates 37A and 37B, and the electrode plate 3 of the second electrode 38.
By applying the high frequency voltage VH1 between 8A and 38B, respectively, a vector electric field having a direction set by the ratio of the electrode constants K1 and K2 is generated in the fuel flow path 36. The alcohol-mixed gasoline G exhibits dielectric polarization due to this electric field, and the output-side electrode plates 37B and 38 are
Different detection voltages V1 and V2 are output from B.

Therefore, it is possible to obtain the same effects as those of the first embodiment described above, and in the present embodiment, the first and second voltage applying means are provided with one oscillator (the oscillator 24 in the present embodiment). ) Can be used to accurately detect an unknown alcohol concentration.

Next, a third embodiment of the present invention will be described with reference to FIGS. 13 and 14. The feature of this embodiment is that an equal high frequency voltage is applied between the electrodes constituting the capacitance type sensor. On the other hand, before and after that, different high frequency voltages are applied, and the detection voltage is derived from between one of the electrodes. The same components as those in the first embodiment described above are designated by the same reference numerals, and the description thereof will be omitted.

In FIG. 13, reference numeral 41 denotes a changeover switch, and the changeover switch 41 is the first electrode 2 of the capacitance type sensor 15.
2 of the lead wires 22 connected to the input side electrode 22A
C, the first oscillator 2 that outputs different peak values
4, the second oscillator 25 is connected between the first oscillator 2 and a signal from a control unit 42, which will be described later.
4 or the second oscillator 25 is selected. Then, when the changeover switch 41 is switched to the (a) side, the oscillator 25 becomes the first and second voltage applying means, and when it is switched to the (b) side, the oscillator 24 becomes the first voltage applying means. The oscillator 25 serves as a second voltage applying unit.

Reference numeral 42 represents a control unit according to the present embodiment, which, like the control unit 29 according to the first embodiment, is roughly composed of an input / output control circuit 43, a processing circuit 44 and a storage circuit 45. Then, the detection voltages V1 and V2 from the output electrode plate 22B of the first electrode 22 of the capacitance type sensor 15 are input to the input side of the input / output control circuit 43 through the differentiating circuit 26. And the output side is connected to the changeover switch 41 through a signal line 46.
Further, in the storage area 45A of the storage circuit 45, in addition to the alcohol concentration detection processing program shown in FIGS. 8 and 9, a fuel injection calculation program, an ignition timing control program (neither is shown), etc. are incorporated. .. Further, in the storage area 45A, the characteristic map I shown in FIG.
The characteristic map II and the characteristic map II shown in FIG.

In the alcohol concentration detecting apparatus of this embodiment having the above-mentioned structure, the changeover switch 41 switches the high frequency voltage applied to the first electrode 22 of the capacitance type sensor 15 to change the fuel flow passage 21. By changing the magnitude and direction of the electric field generated inside, the dielectric polarization of the alcohol-blended gasoline G can be changed. Then, as described in the first embodiment, the characteristic maps I and II shown in FIGS. 6 and 7 are created for the changes in the electrostatic capacitance, and are stored in the storage area 45A of the control unit 42. The unknown ethanol concentration EX and the unknown methanol concentration MX can be detected by the alcohol concentration detection processing program shown in FIGS.

Therefore, also in this embodiment, it is possible to obtain the same effect as that of the first embodiment.

In the third embodiment, the changeover switch 41 is used to select the oscillators 24 and 25, but the present invention is not limited to this, and the attenuator built in the oscillator 24 is changed from the control unit 42. The signal may be adjusted.

In the third embodiment, the first electrode 2
Although the detection voltages V1 and V2 are derived from 2, the present invention is not limited to this, and the detection voltages V1 and V2 from the second electrode 23 are not limited to this.
V2 may be derived.

Further, in the third embodiment, a constant high frequency voltage VH2 is applied to the second electrode 23 of the capacitance type sensor 15.
Is applied, and different high-frequency voltages VH1 and VH2 are selected and applied to the first electrode 22 by the changeover switch 41, and the detection voltages V1 and V2 are derived from the first electrode 22.
The present invention is not limited to this, and as shown in FIG. 14, among the second electrodes 23 of the electrostatic capacity type sensor 15 of the changeover switch 41, it is connected between the input side electrode plate 23A and the oscillator 25,
The high frequency voltage applied to the second electrode 23 may be switched, and the detection voltages V1 and V2 may be detected from the first electrode 22. In this case, the high frequency voltage V applied
The direction of the electric field in the fuel flow path 21 may be changed by H1 and VH2, and the dielectric polarization corresponding to the change may be detected.

Next, a fourth embodiment will be described with reference to FIGS.
The characteristic of the present embodiment is that the alcohol concentration measuring device according to the first embodiment is used as a fuel property determining device to perform the determining process according to the second prior art. The same components as those in the first embodiment described above are designated by the same reference numerals, and the description thereof will be omitted.

In FIG. 15, reference numeral 51 represents a control unit according to the present embodiment, which is substantially composed of an input / output control circuit 52, a processing circuit 53 and a memory circuit 54, and an input of the input / output control circuit 52. On the side, the detection voltages V3 and V4 from the first electrode 22 and the second electrode 23 of the capacitance type sensor 15 are connected so as to be input through the differentiating circuits 26. Further, in the storage area 54A of the storage circuit 54, a fuel injection calculation program, an ignition timing control program (neither is shown), etc. are incorporated in addition to the property determination processing program shown in FIGS. 18 and 19. Furthermore, in the storage area 54A,
Characteristic map III shown in FIG. 16 and characteristic map shown in FIG.
IV and are stored.

Here, the characteristic map III shows three known gasolines A, B and C, two kinds of additives a and b, and various known gasolines in which the concentrations N of the additives a and b are determined. ,
It is created by the detection voltage V3 from the first electrode 22 of the capacitance type sensor 15 by the property determining device of the present embodiment. The horizontal axis represents the concentration N of the additive and the vertical axis represents the detection voltage V3. Detection voltage V3 of 6 kinds of gasoline by combination of 3 kinds of gasoline A, B, C and 2 kinds of additives a, b
It is a graph of the change of. Then, the gasoline A, B, C mixed with the additive a shows the characteristic lines 55, 56, 5
7, the gasolines A, B and C mixed with the additive b have characteristic lines 58, 59 and 60.

On the other hand, the characteristic map IV shows three kinds of gasolines A, B and C, two kinds of additives a and b, and various known gasolines in which the concentrations N of the additives a and b are determined. It is created by the detection voltage V4 from the second electrode 23 of the capacitance type sensor 15 by the property determining device of the present embodiment, and the abscissa indicates the concentration N of the additive and the ordinate indicates the detection voltage V4. Detection voltage V4 of 6 kinds of gasoline by combination of 3 kinds of gasoline A, B, C and 2 kinds of additives a, b
It is a graph of the change of. Then, the gasolines A, B and C mixed with the additive a show characteristic lines 61, 62 and 6
3, the gasolines A, B and C mixed with the additive b become characteristic lines 64, 65 and 66.

Then, the storage area 54A of the storage circuit 54
The storage of the characteristic map III in the inside becomes the first storage means according to the second prior art, and serves as the storage area 54A of the storage circuit 54.
The storage of the characteristic map IV in the second prior art
It becomes a storage means of.

Next, the determination of the gasoline properties of the unknown gasoline G will be described with reference to the programs shown in FIGS. 18 and 19.

First, in step 11, the detection voltage V3X corresponding to the relative permittivity of the gasoline G flowing into the fuel flow path 21 in the capacitance type sensor 15 is supplied from the first electrode 22 to the detection voltage V4X. 2 Read from the electrode 23.

In step 12, from the characteristic map III, the additives a and b at the detection voltage V3X of the characteristic lines 55 to 60 are added.
, N16 (see FIG. 16) of the additive is stored in the storage area 54A of the storage circuit 54. ..

In step 13, the concentrations N of the additives a and b at the detection voltage V4X of the characteristic lines 61 to 66 are calculated from the characteristic map IV (second concentration calculating means according to the second prior art), and this addition is performed. Agent concentration N21, N22, ..., N26 (Fig. 1
7) is stored in the storage area 54A of the storage circuit 54.

In step 14, the group of additive concentrations N11, N12, ..., N16 stored in the storage area 54A and the group of additive concentrations N21, N22 ,. The concentration value of is selected, and the type of gasoline and the type of additive are selected from the selected concentration. For example, in the case of the characteristic lines shown in FIGS. 16 and 17, the density N12 (= N22) is selected.

In step 15, the fuel injection amount and the ignition timing are controlled based on the property state of the gasoline G (type of gasoline, type of additive, concentration of the additive) selected in step 14, and the spark plug is controlled. 2 and injection valve 8
Output a signal to.

However, in the fuel property determining apparatus according to the present embodiment, the capacitance type sensor 15 for detecting the relative permittivity of gasoline G is arranged in the direction orthogonal to the fuel flow passage 21. A high-frequency voltage VH1, VH2 having different peak values V01, V02 is applied to the first electrode 22, the second electrode 23 from the oscillators 24, 25, respectively, to the fuel flow path. By making the electric field in 21 a vector electric field, the gasoline G in the fuel flow path 21 generates a dielectric polarization corresponding to the magnitude of the electric field, and the gasoline G from the first electrode 22 and the second electrode 23 is generated. The detection voltages V3 and V4 as detection signals corresponding to the relative permittivity of are detected.

Further, according to this embodiment, the type of gasoline G, the type of additive, and the concentration of the additive can be accurately selected by the detection method shown in the second prior art. It is possible to configure a fuel property determination device that determines accuracy.

As a result, the ignition advance and retard are corrected according to the property of the gasoline G, and the fuel injection amount is corrected to prevent over leaning and over riching and to provide proper fuel conditions. it can.

In the fourth embodiment, the detection signals are used as the detection voltages V3 and V4, but the present invention is not limited to this, and as shown in FIG.
The high-frequency voltages VH1 and VH2 from the above are input to the control unit 42 as reference signals through the reference signal lines 33 and 34, and the reference signals and the detection voltages V3 and V4 are used to connect between the first electrode 22 and the second electrode 23. Alternatively, the electrostatic capacitance of may be detected.

Also in the fourth embodiment, the second
The same configuration as that of the first embodiment, different electrode constants of the first electrode and the second electrode of the capacitance type sensor are formed, and the same high frequency voltage is applied to each electrode from a common oscillator, The detection voltage may be derived.

Further, in the fourth embodiment as well, the same configuration as that of the third embodiment is adopted, and by changing the application method of the high-frequency voltage applied to the first electrode 22 and the second electrode 23, each one of them is changed. It is also possible to determine the properties of gasoline only by detection from between the electrodes.

Furthermore, in each of the above embodiments, the peak value V01 of the high frequency voltages VH1 and VH2 of the oscillators 24 and 25,
Although the crest value V02 is made different, the present invention is not limited to this, and the frequency may be made different, or the frequency and the crest value may be made different. In this case, The magnitude of the electric field generated between the electrode 22 and the second electrode 23 can be adjusted, and thereby the magnitude of the dielectric polarization generated between the first electrode 22 and the second electrode 23 in the fuel can be made different. , Two different detection voltages V1 and V2
, V3 and V4 can be obtained.

20 to 24, a specific structure of the capacitance type sensor will be described as a fifth embodiment. The same components as those in the first embodiment described above are designated by the same reference numerals, and the description thereof will be omitted.

In the figure, reference numeral 61 denotes an electrostatic capacitance type sensor according to this embodiment, and the external shape of the electrostatic capacitance type sensor 61 is formed in a cylindrical shape.

Reference numeral 62 denotes a cylindrical housing made of an aluminum material. The housing 62 has a square inner peripheral surface, and each surface is a flat surface 62A1, 62A1.
, ..
Male threads 62B, 62B to which the female threads 66A are screwed
And four chamfered portions 62C, 62C, ... Formed in the vicinity of the central portion of the outer peripheral surface in the axial direction and formed in parallel with the respective planes 62A1, and the chamfered portions 62C are provided in the radial direction. , And four connector mounting holes 62D, 62D, ... Having annular step portions 62D1, 62D1 ,.

Reference numeral 63 denotes an insulating case accommodated in the case accommodating portion 62A of the housing 62. The insulating case 63 is made of an insulating resin material such as polytetrafluoroethylene and has a square tubular shape 63A. And a lid portion 63 provided to close both ends of the tubular portion 63A.
B and 63B.

Here, as shown in FIG. 22, the cylindrical portion 63A has a rod-shaped member formed in a substantially "L" shape, with its end faces aligned with each other so that a square hole portion 63A1 can be formed inside. An electrode plate 64, which is assembled and is described later, is provided on each inner peripheral surface.
Electrode attachment part 6 to which A, 64B, 65A and 65B are attached
, 3A2, 63A2, ... Are extended in the axial direction and are recessed, and through holes 63A3, which penetrate in the radial direction, are formed in the respective central portions.
63A3, ... Are drilled.

Further, each of the lid portions 63B is formed in a disc shape, and the disc portion 63B1 is sandwiched between both axial end faces of the housing 62 and the lid body 65, and the central portion of the disc portion 63B1. A square protrusion 63B2 is formed in each of the openings 63A1 at both ends of the hole 63A1.
2 has a through hole 63B3 penetrating in the axial direction.

Reference numeral 64 denotes a first electrode according to this embodiment, and the first electrode 64 has rectangular electrode plates 64A and 64B made of a stainless material as upper and lower electrode mounting portions 63A2.
It is configured by sticking so as to face each other.

Reference numeral 65 also designates a second electrode according to the present embodiment. The second electrode 65 is also composed of rectangular electrode plates 65A and 65B made of a stainless material, and the left and right electrode mounting portions 6 are formed.
It is constructed by sticking so as to face 3A2.

Then, the electrode plates 64A, 6 of the first electrode 64 are formed.
4B and the area of the electrode plates 65A and 65B of the second electrode 65 is S, the opposing electrode plates 64A and 64B and the electrode plate 65.
Assuming that the separation distance between A and 65B is d, the first electrode 64,
The electrode constant K of the second electrode 65 is K = S / d, which is a parallel plate type electrode having the same electrode constant K.

Reference numerals 66, 66 denote lidded cylindrical lids screwed to the male threaded portions 62B of the housing 62. Since the lids 66 are formed on the inner peripheral surface, the threaded portion 66A and the central portion are provided. It is composed of a connection portion 66B that is an inflow port or an outflow port that projects toward the outside, and flow path hole portions 66C and 66C that are provided in the axial direction of each connection portion 66B.

Reference numerals 67, 67, ... Represent connectors fixed to the chamfered portions 62C of the housing 62 by screws 67A, 67A ,. The connectors 67 are formed by BNC connectors and are formed on the base end side. Positioning step 6
7B is inserted into the annular stepped portion 62D1 via a large-diameter O-ring 68, and the core wire 67C is inserted into the connector mounting hole 62D via a small-diameter cylindrical seal member 69, and each core wire 67C is inserted via a lead wire 70. Each electrode plate 64A, 64B, 65
It is connected to A and 65B by means such as soldering.

Reference numeral 71 denotes a fuel flow path, which is a hole 63A1 (electrode plates 64A, 64B of the first electrode 64) formed by an insulating case 63 in the housing 62.
And a portion of the second electrode 65 surrounded by the electrode plates 65A and 65B), and is formed so as to extend linearly in the axial direction inside the capacitance type sensor 61. Then, the fuel flows into the fuel flow passage 71 through the flow passage hole portion 66C of the one lid 66 and the through hole portion 63B3 of the insulating case 63, and the fuel in the fuel flow passage 71 has the other through hole portion. 63B
3 and the flow path hole 66C of the lid 66.

The capacitance type sensor 6 configured as described above
In the first example, regarding the axial leakage of the fuel that has flowed into the fuel flow passage 71, each male screw portion 62 of the housing 62 is
Since the internal thread portion 66A of each lid 66 is screwed onto the B via the disc portion 63B1 of each lid portion 63B, each disc portion 63B1 serves as a seal member, and the housing 62 and each Fuel leakage from between the lids 66 is prevented. On the other hand, regarding the leakage in the radial direction, the cylindrical portion 6 of the insulating case 63 is
The fuel leaked from the mating portion of 3A reaches between each flat surface 62A1 of the housing 62 and the cylindrical portion 63A of the insulating case 63, and each through hole 63A3 and each connector mounting hole 62D.
Through the through hole 63A3, the connector mounting hole 62D, and the positioning step portion 67 of the connector 67.
An O-ring 68 and a tubular seal member 69 are fitted between B and the core wire 67C to prevent fuel from leaking to the outside. As a result, according to the present embodiment, it is possible to form the capacitance type sensor 61 that can not only be made compact but can also reliably prevent fuel leakage.

Further, the capacitance type sensor 6 according to the present embodiment.
1 shown in the first embodiment described above, the capacitance sensor 61 according to the present embodiment is connected to the connecting portion 66B of each lid 66 in the middle of the fuel pipe 11, like,
By connecting each connector 67 to the first oscillator 24, the second oscillator 25, and each differentiating circuit 26 via a BNC lead wire, the electrode plates 64A and 64B of the first electrode 64 and the second electrode which face each other are connected. 65 electrode plate 65A,
High frequency voltages VH1 and VH2 having different peak values can be applied to 65B. Then, this capacitance type sensor 61
In the above, since the first electrode 64 and the second electrode 65 have the same electrode constant K, a vector-like electric field is generated in the fuel flow path 71, and the electric field causes the dielectric polarization of the fuel, The detection voltages V1 and V2 are output from the first electrode 64 and the second electrode 65 to the control unit 29.
As a result, the properties of the alcohol-blended gasoline and gasoline described above can be determined.

The capacitance type sensor 61 according to the fifth embodiment can be applied not only to the above-mentioned first embodiment but also to the second to fourth embodiments.
When used in the second embodiment, the area S or the separation distance d of each of the electrode plates 64A and 64B forming the first electrode 64 and the electrode plates 65A and 65B forming the second electrode 65 is changed. , The electrode constants K may be differently used.

Next, a concrete structure of the capacitance type sensor as the sixth embodiment will be described with reference to FIGS. 25 to 27.

In the capacitance type sensor according to the present embodiment, the fuel flow path is formed into an annular shape so that the fuel introduced from the inflow port is branched, and the fuel flows in an arc shape, merges in front of the outflow port and flows out. One of the electrodes is formed as a parallel plate type electrode formed by a pair of annular plates, one of which is along the annular fuel flow path so as to be orthogonal to the fuel in the fuel flow path, and the other of the electrodes is formed. The electrodes are configured as coaxial cylindrical electrodes. The same components as those in the first and second embodiments described above are designated by the same reference numerals, and the description thereof will be omitted.

In FIG. 25, reference numeral 81 denotes an electrostatic capacitance sensor according to this embodiment, and the external shape of the electrostatic capacitance sensor 81 is formed in a short cylindrical shape.

Reference numeral 82 denotes the first electrode or the second electrode according to this embodiment.
A coaxial cylindrical electrode that constitutes one of the electrodes is shown. The coaxial cylindrical electrode 82 is composed of a cylindrical electrode plate 83, which will be described later, and a cylindrical electrode shaft 85 located at the axial center of the cylindrical electrode plate 83. It is roughly composed.

Reference numeral 83 denotes a cylindrical electrode plate which constitutes one electrode plate of the coaxial cylindrical electrode 82, and the cylindrical electrode plate 83 has a cylindrical portion 83A formed of a stainless material in a short cylindrical shape. , The connecting portions 83B and 83B, which serve as electrical inlets or outlets and are provided so as to project radially outward of the tubular portion 83A, and the axial direction of each connecting portion 83B. Flow path hole portions 83C, 8 formed
3C, and annular flange portions 83D, 83D formed at the upper and lower ends of each of the cylindrical portions 83A.

Reference numerals 84 and 84 denote annular insulating members. Each annular insulating member 84 is provided on each flange portion 83D of the cylindrical electrode plate 83, and is formed of polytetrafluoroethylene into a substantially "L" shape. There is.

Reference numeral 85 denotes a columnar electrode shaft which constitutes the other electrode plate of the coaxial cylindrical electrode. The columnar electrode shaft 85 is made of a stainless material in a short columnar shape, and the connector portion 85A projects downward. Has been formed.

Reference numeral 86 denotes the first electrode or the second electrode according to this embodiment.
A parallel plate type electrode constituting the other electrode of the electrodes is shown, and the parallel plate type electrode 86 is a pair of annular electrode plates 87,
And 87.

Here, 87 and 87 denote annular electrode plates which form a parallel plate type electrode, and annular step portions 87A and 87A are formed on the outer peripheral sides of the facing surfaces of the respective annular electrode plates 87,
The annular stepped portions 87A are disposed on the flanged portions 83D formed above and below the cylindrical electrode plate 83 via the annular insulating members 84, respectively.

Reference numerals 88 and 88 denote disc-shaped insulating members made of polytetrafluoroethylene. The disc-shaped insulating members 88 are provided on the inner peripheral side of the annular electrode plate 87, respectively, and the columnar members are provided between them. The electrode shaft 85 is held. In addition, the disk-shaped insulating member 88 located on the lower side
An insertion hole 88A through which the connector portion 85A of the columnar electrode shaft 85 is inserted and projected is formed in the hole.

Reference numeral 89 denotes a fuel flow passage, which is a cylindrical electrode plate 83 forming the coaxial cylindrical electrode 82,
It becomes a portion surrounded by each of the annular electrode plates 87 forming the columnar electrode shaft 85 and the parallel plate type electrode 86, and as shown by the arrow in FIG. 26, the fuel flowing in from one connecting portion 83B is in two directions. It is branched, flows along an arc, and joins and flows out before the other connecting portion 83B.

The inner diameter of the cylindrical electrode plate 83 is a, the outer diameter of the cylindrical electrode shaft 85 is b, and the area of the portion of each annular electrode plate 87 which becomes the fuel flow passage 89 is S '(S' = π ( a ² -b ²⁾
/ 4) and the electrode plate distance d0.

Here, the electrode constant K1 'of the coaxial cylindrical electrode 82 and the electrode constant K2' of the parallel plate type electrode 86 of the capacitance type sensor 81 according to the present embodiment are as shown in the following formula 1.

[0129]

[Equation 1]

Although the capacitance type sensor 81 according to the present embodiment is constructed in this way, it can be made more compact than the capacitance type sensor 61 according to the fifth embodiment described above.

Then, in the capacitance type sensor 81 according to the present embodiment, as shown in FIG. 1 shown in the first embodiment,
The connecting portion 83B is connected in the middle of the fuel pipe 11, and as shown in FIG. 12 of the second embodiment, the oscillator 24 is connected to one connecting portion 83B, the connector portion 85A and each annular electrode plate 87 via lead wires. And applying the high frequency voltage VH1 to the cylindrical electrode plate 83 forming the coaxial cylindrical electrode 82, the cylindrical electrode shaft 85, and the annular electrode plate 87 forming the parallel flat plate electrode 86 by connecting to the differentiating circuit 26. You can
Since the capacitance type sensor 81 is composed of two kinds of electrodes having different electrode constants K1 'and K2', a vector electric field is generated in the fuel flow passage 89, and this electric field is generated. As a result, the fuel in the fuel flow path 89 causes dielectric polarization, and the detection voltages V1, V
2 is output to the control unit 29. As a result, the properties of the alcohol-blended gasoline and gasoline described above can be determined.

The capacitance type sensor 81 according to the sixth embodiment is applicable not only to the second embodiment described above, but also the parallel plate type electrode 86 and the coaxial cylindrical electrode 82.
It is needless to say that the electrode constants K1 'and K2' can be used in the first, third and fourth embodiments if they are formed to have the same value.

[0133]

As described in detail above, according to the capacitance type sensor of the present invention, the fuel flow path is formed with the inlet and the outlet, and the fuel flows from the inlet to the outlet. A pair of first electrodes provided separately from the side surface of the fuel flow path and opposed to each other through the flowing fuel, and a side surface of the fuel flow path, provided so as to be orthogonal to the first electrode, It is composed of a pair of second electrodes opposed to each other through the flowing fuel, and each of the electrodes is constituted by a parallel plate type electrode or a coaxial cylindrical electrode on one side and a parallel plate type electrode on the other side. The two electrodes can be arranged compactly with respect to the fuel flow path, and two kinds of electric signals with respect to the relative permittivity of the fuel can be derived using a single capacitance type sensor.

Further, according to the fuel property determining apparatus of the present invention, first and second voltage applying means for applying a high frequency voltage to the first and second electrodes of the capacitance type sensor described above, respectively, Detection processing for detecting an electric signal corresponding to the property of fuel from between at least one of the first and second electrodes when a high-frequency voltage is applied to the first and second electrodes by each voltage application means And applying a high-frequency voltage from the first and second voltage applying means to the first and second electrodes, a vector electric field can be applied to the fuel flowing through the fuel passage. By changing the magnitude of this electric field and the direction thereof, the magnitude of the dielectric polarization in the fuel can be changed to detect different electric signals from the capacitance type sensor.

As described above, by using the two kinds of electric signals and performing the signal processing by the detection processing means, even when the fuel is, for example, three kinds of alcohol-mixed gasoline such as a mixture of methanol, ethanol and gasoline, The concentration of can be accurately detected. Further, even if the type of gasoline, the type of additive, and the concentration of the additive are unknown, the concentration and the like can be accurately detected. Therefore,
It is possible to accurately determine the property of the fuel, and it is possible to accurately control the fuel injection amount and the ignition timing. Then, the driving performance of the vehicle can be surely improved.

[Brief description of drawings]

FIG. 1 is an overall configuration diagram of a fuel injection amount control device according to a first embodiment of the present invention.

FIG. 2 is an overall configuration diagram showing a circuit configuration of an alcohol concentration measuring device according to a first embodiment.

FIG. 3 is an enlarged exploded perspective view showing a capacitance type sensor of the alcohol concentration measuring apparatus according to the first embodiment.

FIG. 4 is a cross-sectional view as seen from the direction of arrows IV-IV in FIG.

5 is a cross-sectional view as seen from the direction of arrow V-V in FIG.

FIG. 6 is a characteristic diagram showing a characteristic map I according to measurement results of known alcohol-blended gasoline.

FIG. 7 is a characteristic diagram showing a characteristic map II based on measurement results of known alcohol-blended gasoline.

FIG. 8 is a flow chart showing a measurement process of a mixed concentration of unknown alcohol-blended gasoline.

FIG. 9 is a flowchart following FIG. 8;

FIG. 10 is a mixed line L1 calculated from characteristic maps I and II.
FIG. 5 is an explanatory view showing a method of calculating L, L2 and a mixed concentration.

FIG. 11 is an overall configuration diagram showing a circuit configuration of an alcohol concentration measuring device according to a modification of the first embodiment of the present invention.

FIG. 12 is an overall configuration diagram showing a circuit configuration of an alcohol concentration measuring device according to a second embodiment of the present invention.

FIG. 13 is an overall configuration diagram showing a circuit configuration of an alcohol concentration measuring device according to a third embodiment of the present invention.

FIG. 14 is an overall configuration diagram showing a circuit configuration of an alcohol concentration measuring device according to a modification of the third embodiment of the present invention.

FIG. 15 is an overall configuration diagram showing a circuit configuration of a fuel property determination device according to a fourth embodiment of the present invention.

FIG. 16 is a characteristic diagram showing a characteristic map III based on measurement results of gasoline containing a known additive.

FIG. 17 is a characteristic diagram showing a characteristic map IV based on measurement results of gasoline containing a known additive.

FIG. 18 is a flow chart showing a process for determining the properties of gasoline containing an unknown additive.

FIG. 19 is a flowchart following FIG. 18;

FIG. 20 is a perspective view of a capacitance type sensor according to a fifth embodiment of the present invention.

21 is a vertical cross-sectional view of the capacitance type sensor shown in FIG.

22 is a cross-sectional view of the capacitance type sensor shown in FIG.

FIG. 23 is an enlarged view of an essential part showing an enlarged part b in FIG. 22.

24 is an enlarged view of an essential part showing an enlarged part a in FIG.

FIG. 25 is a perspective view of a capacitance type sensor according to a sixth embodiment of the present invention.

FIG. 26 is a cross-sectional view of the capacitance type sensor shown in FIG. 25.

FIG. 27 is a vertical sectional view of the capacitance type sensor shown in FIG. 25.

[Explanation of symbols]

15, 35 Capacitance sensor 17 Casing 18 Inflow pipe (inflow port) 19 Outflow pipe (outflow port) 21, 36 Fuel flow path 22, 37 First electrode 23, 38 Second electrode 24 Oscillator (first voltage application 25) Oscillator (second voltage applying means) 29, 42, 51 Control unit (detection processing means) 41 Changeover switch 61 Capacitive sensor 62 Housing 64 First electrode (parallel plate type electrode) 65 Second electrode ( Parallel plate type electrode) 66 Lid body 66B Connection part (inlet / outlet port) 66C Flow path hole part 71 Fuel flow path 81 Capacitive sensor 82 Coaxial cylindrical electrode 83 Cylindrical electrode plate 83B Connection part (inflow port, Outflow port) 85 Cylindrical electrode shaft 86 Parallel plate type electrode 87 Annular electrode plate 89 Fuel flow path K, K1, K2 Electrode constant

Claims (7)

[Claims] 1. A fuel flow passage, in which a fuel inlet and an outlet are formed, the fuel flows from the inlet toward the outlet, and a fuel which is provided separately from a side surface of the fuel flow passage. A pair of first electrodes opposed to each other via a fuel cell, and a pair of second electrodes spaced apart from the side surface of the fuel channel so as to be orthogonal to the first electrode and opposed to each other via a flowing fuel. Capacitive sensor made by. 2. The fuel flow passage is linearly formed so that the fuel flowing from the inlet flows in the axial direction and flows out from the outlet, and the first and second electrodes are provided with the fuel flow. The electrostatic capacitance type sensor according to claim 1, wherein the electrodes are arranged as parallel plate type electrodes so as to be orthogonal to each other. 3. The fuel flow path is formed in an annular shape so that the fuel introduced from the inflow port is branched and flows in an arc shape, merges in front of the outflow port, and flows out. In the two electrodes, one electrode is formed by a pair of annular plates along the annular fuel flow path and the other electrode is formed as a coaxial cylindrical electrode so as to be orthogonal to the fuel flow path. The capacitive sensor according to claim 1, wherein 4. A fuel flow passage, in which a fuel inlet and an outlet are formed, the fuel flows from the inlet toward the outlet, and a fuel which is provided separately from a side surface of the fuel flow passage and flows. A pair of first electrodes opposed to each other with a pair of second electrodes spaced apart from each other on the side surface of the fuel flow path and orthogonal to the first electrode, and opposed to each other with a flowing fuel therebetween; First and second voltage applying means for applying a high frequency voltage to the first and second electrodes, respectively, and when the high frequency voltage is applied to the first and second electrodes by each of the voltage applying means, A fuel property determination device comprising a detection processing means for detecting an electrical signal corresponding to the property of the fuel from between at least one of the second electrodes. 5. The first and second voltage applying means are the first and second voltage applying means.
5. The fuel property determination device according to claim 4, wherein different high frequency voltages are applied to the second electrodes, and the detection processing means detects electrical signals corresponding to the properties of the fuel from between the first and second electrodes. 6. The first or second electrode is provided on the first and second electrodes.
While the same high frequency voltage is applied from any of the voltage applying means, different high frequency voltages are applied to the first and second electrodes from the first and second voltage applying means, respectively, and the detection processing is performed. 5. The fuel property discriminating apparatus according to claim 4, wherein the means detects an electric signal corresponding to the property of the fuel from between one of the first and second electrodes. 7. The first and second electrodes are formed so as to have different electrode constants, and the same high frequency voltage is applied to the first and second electrodes from either the first or second voltage applying means. 5. The detection processing means detects an electric signal corresponding to the property of the fuel from between the first and second electrodes, respectively.
The fuel property determination device described.