JPH075143A - Fuel properties decision system - Google Patents

Abstract

PURPOSE:To detect the properties and the concentration of additive of an unknown fuel quickly and highly accurately by determining the difference between signals, representative of the dielectric constant of the unknown fuel, detected through first and second signal detecting means and then detecting one of heavy and light characteristics. CONSTITUTION:A capacitive sensor 15 has first and second electrodes 18, 19 being applied 27 with first (second) voltages VH, VH (VH, VL) and applying a vector field to an unknown fuel flowing through a fuel channel 25 in order to detect a signal corresponding to the dielectric constant of the fuel. A processing circuit 28 receives the detection signal and delivers detection voltages VOA, VOB to a control unit 36. The unit 36 operates the difference DELTAV between the voltages VOA, VOB and makes a decision whether the difference DELTAV exceeds a voltage difference characteristic curve. If the answer is YES (NO), a decision is made that the fuel is heavy (light) and then an MTBE concentration M is calculated by selecting the voltage difference characteristics for heavy (light) fuel. This system allows quick and highly accurate decision of the properties of fuel and the concentration of additive.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fuel property discriminating apparatus suitable for discriminating the properties of fuel (gasoline) used in automobile engines and the like such as heavy and light.

[0002]

2. Description of the Related Art Generally, genuine gasoline used as fuel for automobile engines includes light gasoline mainly containing hydrocarbons such as heptane and pentane and heavy gasoline mainly containing hydrocarbons such as benzene. There is gasoline, and if further subdivided, there are three types: light gasoline, medium gasoline, and heavy gasoline.

In an engine used for an automobile, the ignition timing and the like are usually set to match light gasoline. However, recently, due to the generalization of the use of heavy gasoline and the enforcement of the Air Pollution Law, the heavy gasoline is being used.

Therefore, matching light gasoline,
When heavy gasoline is used as fuel in an engine that is set to control ignition timing, the ignition timing is delayed compared to light gasoline, resulting in a tendency to become lean as a whole and startability at low temperatures. However, there is a problem that driving performance is deteriorated. Further, even when the vehicle is in a running state, when heavy gasoline is used, not only the driving performance such as breathing phenomenon is deteriorated, but also inconvenient combustion causes a problem that harmful components in the exhaust gas increase.

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, the overall tendency becomes overrich and the ignition There is a problem that "smoldering" occurs in the plug.

In order to solve such problems, the present applicant has previously proposed Japanese Patent Application No. 2-278759 (Japanese Patent Laid-Open No. 4-155252) according to the properties of light, medium and heavy gasoline. Capacitance type gasoline property detection sensor whose output voltage changes according to the temperature, a temperature sensor for detecting the temperature of the gasoline, and a relationship between the output voltage from the gasoline property detection sensor and the temperature detected by the temperature sensor. , First determining means for determining whether it is medium quality or temporary heavy gasoline, and when it is determined to be temporary heavy gasoline by the first determining means, based on output signals from the respective sensors Calculate the temperature gradient,
We proposed a gasoline property discriminating apparatus composed of a second discriminating means for discriminating between light and medium gasoline and genuine heavy gasoline based on this temperature gradient (hereinafter referred to as "conventional technology").

In the prior art, gasoline is judged to be pure heavy gasoline or medium or light gasoline based on the difference in output voltage obtained by the difference in dielectric constant depending on the difference in properties and the difference in fuel temperature characteristics. In doing so, even if the gasoline contains an alcohol component such as an additive, the genuine heavy gasoline is determined with the influence of the alcohol component removed. This allows
It is possible to provide an extremely accurate gasoline property determination device, and as a result, the ignition advance and retard are corrected according to the property of gasoline. Further, it is possible to correct the fuel injection amount, prevent over lean and over rich, and provide an appropriate fuel condition.

[0008]

By the way, in the above-mentioned prior art, since the determination is made by using the temperature gradient of gasoline, in order to make an accurate determination, the temperature difference in the fuel temperature is required and the responsiveness is improved. There is a problem that becomes worse.

In particular, at the time of starting, there is a problem that there is no temperature difference in gasoline, the property of gasoline cannot be accurately determined, and engine control cannot be performed accurately.

The present invention has been made in view of the above-mentioned problems of the prior art, and it is a fuel property that enables to detect an unknown gasoline property and an additive concentration quickly and with high accuracy, and to perform appropriate engine control. An object is to provide a discriminating device.

[0011]

In order to solve the above-mentioned problems, a fuel property determination device according to the present invention is characterized in that an electrostatic capacity sensor and a first voltage are applied to the electrostatic capacity sensor. First signal detection means for detecting a signal corresponding to the relative permittivity of fuel from the capacitance type sensor, and fuel from the capacitance type sensor with a second voltage applied to the capacitance type sensor. Second signal detecting means for detecting a signal according to the relative permittivity of the above, and known fuel obtained by sequentially mixing two kinds of fuels having different properties with an additive at a predetermined concentration by the first signal detecting means. Storage means for storing a signal difference characteristic between the signal for the known additive concentration for each fuel and the signal for the known additive concentration for each known fuel by the second signal detection means as two characteristics showing different properties; , Using the first signal detection means And a signal corresponding to the relative permittivity of the unknown fuel is detected, and a signal corresponding to the relative permittivity of the unknown fuel is detected using the second signal detecting means, and a signal difference for calculating this signal difference is detected. The calculation means, the property determination means for determining the property of the unknown fuel on the basis of the signal difference from the signal difference calculation device, and selecting one of the two characteristics stored in the storage device, and the property determination means. It is composed of concentration calculating means for calculating an unknown additive concentration based on one of the selected characteristics and the signal difference from the signal difference calculating means.

Further, in the capacitance type sensor, a fuel inflow port and a fuel outflow port are formed, and a fuel flow passage through which fuel flows from the inflow port toward the outflow port and a fuel flow passage in the middle of the fuel flow passage. A pair of first electrodes provided so as to face each other with a fuel interposed therebetween, and a pair of first electrodes provided so as to face each other with a fuel flowing in the middle of the fuel flow path interposed therebetween and orthogonal to the first electrodes. It is desirable to be composed of two electrodes.

[0013]

With the above structure, for the known fuel in which the additive is sequentially mixed at a predetermined concentration with two kinds of fuel having different properties, such as a light fuel and a heavy fuel, the signal by the first signal detecting means and the second signal by the second signal are detected. The signal difference characteristic of the signal by the signal detecting means is defined as two characteristics showing different properties.
It is stored in the storage means in advance.

Next, the signals corresponding to the relative permittivity of the unknown fuel are detected using the first and second signal detecting means, and the signal difference is calculated by the signal calculating means. And
Based on the signal difference calculated by the signal difference calculating means, the property determining means determines the unknown fuel property, selects one of the two properties stored in the storage device, and outputs the signal from this property. The concentration calculating means calculates the additive concentration based on the difference. This makes it possible to determine the properties of the fuel and the additive concentration.

Further, the capacitance type sensor is provided with a pair of the first electrode and the second electrode so as to be orthogonal to the fuel flow path, and one of the electrodes serves as an electrode for varying the applied voltage. , The other electrode is used as an electrode for detecting a signal corresponding to the relative dielectric constant of the fuel, and one of the two electrodes is connected to 2
It is possible to detect three different signals.

[0016]

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

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 generally configured from a piston 1C that reciprocates in the cylinder 1A. Reference numeral 2 denotes 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 36 described later. 1
It is designed to burn (explode) the air-fuel mixture in A.

A cylinder 1A of the cylinder 3 has a base end side which serves as a branch pipe.
Shows an intake manifold provided on the intake side of the cylinder head 1B, an intake filter 4 is provided on the tip side of the intake manifold 3, and an air flow meter 5 for measuring the intake air amount and a throttle valve switch 6 are provided on the way. An attached throttle valve 7 etc. is provided,
Further, an injection valve 8 is provided near the cylinder head 1B, and the injection valve 8 injects gasoline G into the engine 1 in response to an injection signal from the control unit 36.

A gasoline tank 9 stores gasoline G inside, and an in-tank type gasoline pump 10 is provided in the gasoline tank 9. Reference numeral 11 is a gasoline pipe, and one end of the gasoline pipe 11 is a gasoline filter 12
Connected to the discharge side of the gasoline pump 10, the other end connected to the injection valve 8 and the inflow side of the pressure regulator 13, and the outflow side of the pressure regulator 13 connected to the gasoline tank 9 via the return pipe 14. ing.

Reference numeral 15 denotes, for example, an electrostatic capacitance type sensor provided in the middle of the gasoline pipe 11. The electrostatic capacitance type sensor 15 statically changes the relative permittivity due to the property state of the gasoline G flowing in the gasoline pipe 11. It is detected as an electric capacitance, and a detection signal from the electrostatic capacitance type sensor 15 is output to a control unit 36 as a detection voltage via a detection processing circuit 26 described later.

Here, the capacitance type sensor 15 according to the present embodiment has a cylindrical outer shape as shown in FIGS. That is, reference numeral 16 denotes a cylindrical housing made of an aluminum material.
Has a square inner surface and each surface is a flat surface 16A1.
, 16A1, ... Formed on the outer circumference of both ends on a case housing 16A for housing an insulating case 17 described later.
Male screw part 16 with which female screw part 20A of each lid 20 is screwed
B, 16B and formed near the axial center of the outer peripheral surface,
Four chamfered portions 16C, 16C, ... Formed so as to be parallel to the respective planes 16A1, and the chamfered portions 16 respectively.
A circular step portion 16D1, 16D1,
It is composed of four connector mounting holes 16D, 16D, ...

Reference numeral 17 denotes an insulating case accommodated in the case accommodating portion 16A of the housing 16, and the insulating case 17 is made of an insulating resin material such as polytetrafluoroethylene and has a square tubular cylindrical portion 17A. And a lid portion 17 provided so as to close both ends of the tubular portion 17A.
B and 17B.

Here, as shown in FIG. 5, the cylindrical portion 17A has a rod-shaped member formed in a substantially "L" shape with its end faces aligned so that a square hole portion 17A1 can be formed inside. The electrode plates 18A, which will be described later, are assembled to each inner peripheral surface.
Electrode attachment portion 17A to which 18B, 19A and 19B are attached
2, 17A2, ... Are axially extended to be recessed, and a lead wire insertion hole 17A penetrating in the radial direction at the center thereof.
3, 17A3, ... Are drilled.

Further, each of the lid portions 17B is formed in a disc shape, and is sandwiched between both axial end surfaces of the housing 16 and the lid body 20, and a central portion of the disc portion 17B1. And a projecting portion 17B2 formed in a square shape so as to be inserted into both end side opening portions of the hole portion 17A1. The projecting portion 17B2 has a through hole 1 penetrating in the axial direction.
7B3 is drilled.

Reference numeral 18 denotes a first electrode according to this embodiment, which is composed of rectangular electrode plates 18A and 18B made of stainless steel.
8B is attached so as to face the upper and lower electrode mounting portions 17A2 and 17A2, respectively.

Reference numeral 19 also designates a second electrode according to the present embodiment. The second electrode 19 is also composed of rectangular electrode plates 19A and 19B made of a stainless material.
A and 19B are attached so as to face the left and right electrode mounting portions 17A2 and 17A2, respectively.

Then, the electrode plates 18A, 1 of the first electrode 18
8B and the surface area of the electrode plates 19A and 19B of the second electrode 19 is S, and the opposing electrode plates 18A and 18B and the electrode plate 1 are
Assuming that the separation distance between 9A and 19B is d, the first electrode 1
8, the electrode constant K of the second electrode 19 is K = S / d,
It is configured as a pair of parallel plate electrodes having the same electrode constant K.

Numerals 20 and 20 denote lidded cylindrical lids screwed to the male screw portions 16B of the housing 16, and the lid body 20 is formed on the inner peripheral surface thereof and has a screw portion 20A and a central portion. It is composed of connecting portions 20B, 20B that are provided as an inflow port or an outflow port that are provided to project outward, and flow path hole portions 20C, 20C that are bored in the axial direction of each of the connecting portions 20B.

Reference numerals 21, 21, ... Show connectors which are fixed to the chamfered portions 16C of the housing 16 by screws 21A, 21A ,. The connector 21 is formed by a BNC connector and is formed on the base end side. Positioning step 2
1B is inserted into the annular step portion 16D1 via a large-diameter O-ring 22, and the core wire 21C is inserted into the connector mounting hole 16D via a small-diameter cylindrical seal member 23. Each core wire 21C is inserted via a lead wire 24. Each electrode plate 18A, 18B, 19
It is connected to A and 19B by means such as soldering.

Reference numeral 25 denotes a fuel flow path, which is a hole 17A1 (electrode plates 18A, 18B of the first electrode 18) formed by an insulating case 17 in the housing 16.
And a portion of the second electrode 19 surrounded by the electrode plates 19A and 19B), and is formed so as to extend linearly in the axial direction in the capacitance type sensor 15. Then, the fuel flows into the fuel flow path 25 through the flow path hole portion 20C of the one lid 20 and the through hole 17B3 of the insulating case 17, and the fuel in the fuel flow path 25 passes through the other through hole 17B3 and It flows out through the passage hole portion 20C of the lid body 20.

The capacitance type sensor 1 having such a configuration
5, regarding the leakage of the fuel that has flowed into the fuel flow path 25 in the axial direction, the male screw portions 16 of the housing 16
Since the internal thread portion 20A of each lid 20 is screwed onto the B via the disc portion 17B1 of each lid portion 17B, each disc portion 17B1 serves as a seal member, and the housing 16 and each Fuel leakage from between the lids 20 is prevented. On the other hand, regarding the radial leakage, the cylindrical portion 1 of the insulating case 17
The fuel leaking from the mating portion of 7A reaches between each flat surface 16A1 of the housing 16 and the cylindrical portion 17A of the insulating case 17, and leaks to the outside through each lead wire insertion hole 17A3 and each connector mounting hole 16D. But insert hole 17
An O-ring 22 and a tubular seal member 23 are fitted between A3, the connector mounting hole 16D and the positioning step portion 21B of the connector 21, and the core wire 21C to prevent fuel leakage to the outside.

Next, referring to FIG. 1 and FIG. 7, the fuel property discriminating apparatus according to this embodiment will be described. The fuel property determination device includes a detection processing circuit 26 and a control unit 36 in addition to the capacitance sensor 15 described above.

Here, the detection processing circuit 26, as shown in FIG. 7, applies a voltage VH or VL to the electrodes 18 and 19 of the capacitance type sensor 15, respectively.
And a processing circuit 28 that performs detection processing on the detection signal from the capacitance type sensor 15.

The voltage applying device 27 includes an oscillator 29 that oscillates a high frequency wave having a frequency f and a high peak value, and a filter circuit 30 that removes noise from the high frequency wave from the oscillator 29 and outputs an applied voltage VH. An attenuator circuit 31 for switching a high-frequency peak value from the oscillator 29 between a high peak value and a low peak value, and an applied voltage VH or a low wave having a high peak value by removing noise from the high frequency from the attenuator circuit 31. The filter circuit 32 outputs a high applied voltage VL.

Then, the voltage applying device 27 applies the applied voltage (VH, VH) as the first voltage to the first electrode 18 and the second electrode 19 of the capacitance type sensor 15, respectively. On the other hand, the switching control of the attenuator circuit 31 by the control unit 36 applies the applied voltages (VH, VL) as the second voltage to the first electrode 18 and the second electrode 19, respectively.

On the other hand, the processing circuit 28 differentiates the detection signal from the capacitance type sensor 15 into a differentiating circuit 33.
And an arithmetic circuit 34 for arithmetically operating the output from the differentiating circuit 33.
(Full-wave rectifier circuit + smoothing circuit) and a filter circuit 35 for removing output noise from the arithmetic circuit 34. The filter circuit 35 outputs detected voltages V0A and V0B to the control unit 36. ing.

Here, the first of the capacitance type sensor 15
Applied voltage V which is the first voltage applied to the electrodes 18 and the second electrodes 19.
A first configuration according to the present invention is a configuration in which H and VH are applied respectively, a vector electric field is applied to the fuel in the fuel flow path 25 from the electrodes 18 and 19, and the detection voltage V0A corresponding to the relative permittivity of the fuel is detected. It is a specific example of the signal detection means. In addition, the applied voltage VH that is the second voltage is applied to the first electrode 18 and the second electrode 19.
, VL is applied to detect the detection voltage V0B corresponding to the relative permittivity of the fuel in the fuel passage 25, which is a specific example of the second signal detecting means according to the present invention.

Reference numeral 36 represents a control unit according to the present embodiment, which is composed of, for example, a microcomputer, and the control unit 36 is composed of a memory circuit (not shown) composed of RAM, ROM and the like. In addition to the property determination processing program shown in FIG. 11, an injection amount calculation program, an ignition timing control program (neither is shown), etc. are incorporated.
Further, in the storage area 36A, characteristic lines 41, which will be described later,
42 gradients, intercepts, etc. are stored.

FIG. 8 shows a specific circuit configuration of the voltage applying device 27 and the processing circuit 28 of the detection processing circuit 26. The attenuator circuit 31 of the voltage applying device 27 includes an adjusting resistor 31A. 31A is connected to the output side of the control unit 36 through a lead wire 36B, and the control signal from the control unit 36 switches the resistance value of the adjusting resistor 31A between high and low, thereby electrostatically removing the voltage from the voltage applying device 27. Capacitive sensor 15
The voltage applied to the second electrode 19 is switched to the applied voltage VH or VL.

On the input side of the control unit 36, in addition to the air flow meter 5, the throttle valve 7, a crank angle sensor for detecting the number of revolutions of the engine 1, an engine switch, various sensors such as a water temperature sensor, an oxygen sensor and the like. The capacitance type sensor 15 and the like are connected, and the ignition plug 2, the injection valve 8 and the like are connected to the output side. The detection signal from the capacitance sensor 15 is processed by the detection processing circuit 26, and the control unit 36 outputs detection voltages V0A and V0B corresponding to the capacitance of the fuel.
Is output to.

Here, for two types of gasoline consisting of heavy gasoline and light gasoline, for example, the concentration of methyl tert-butyl ether as an additive (hereinafter referred to as "MTB
(E concentration M ”) is referred to as a known heavy mixed gasoline, and a light mixed gasoline is referred to as B.

In the characteristic diagram shown in FIG. 9, the characteristic lines 37 and 38 are the first electrodes 18 and 18 of the capacitance type sensor 15.
Detection when the above-described known heavy mixed gasoline A and light mixed gasoline B are flown through the fuel flow path 25 in a state where the applied voltages VH and VH are applied to the second electrode 19 (first signal detecting means). The results of the voltage V0A are shown. The characteristic lines 39 and 40 are the same as the capacitance type sensor 15
In the state where the applied voltages VH and VL are respectively applied to the first electrode 18 and the second electrode 19 (second signal detecting means) of the known heavy mixed gasoline A and the light mixed gasoline B, It shows the result of the detection voltage V0B when flowing. That is, in FIG. 9, heavy mixed gasoline A
The characteristic lines 37 and 39 of (heavy fuel) have slopes a1 and c1.
, The intercepts are b1 and d1, and the characteristic lines 38 and 40 of the light mixed gasoline B (light fuel) have slopes a2 and c2 and intercepts b2 and d2.

Further, in the characteristic diagram shown in FIG. 10, characteristic lines 41 and 42 are known heavy mixed gasoline A (heavy fuel).
And a known light mixed gasoline B (light fuel) voltage difference characteristic line, respectively. The voltage difference characteristic lines 41 and 42 are the detected voltage V0A and the second detected voltage V0A by the above-mentioned first signal detecting means. The difference (voltage difference ΔV) in the detected voltage V0B by the signal detecting means is shown for each MTBE concentration M. Since the characteristic lines 37 to 40 described above are linear characteristics, the voltage difference characteristic lines 41 and 42 are also linear. And is obtained as in the following Equation 1.

[0044]

[Equation 1]

The slopes α1, α2 and the intercepts β1, β2 obtained from the voltage difference characteristic lines 41, 42 by the storage means are stored in the storage area 36A.

Here, in the property determining apparatus according to the present embodiment, the shaded area in FIG. 10 (where the MTBE concentration M is about 2).
Fuel of 5% or more) is heavy mixed gasoline A (heavy fuel)
Since both the light mixed gasoline B (light fuel) have the same voltage difference ΔV, the properties cannot be determined. However, the MTBE concentration M added to normal gasoline is MAX 7% in Japan and MAX 1 outside Japan.
Since it is 5%, there is no particular problem in the normal determination of gasoline properties.

Next, the gasoline property determination process for the unknown gasoline G will be described based on the program of FIG. 11 with reference to the characteristic diagram of FIG.

First, in step 1, the first voltage is applied to the capacitance type sensor 15, the detection voltage V0A from the processing circuit 28 is read, and the second voltage is applied, and the second voltage is applied from the processing circuit 28. The detection voltage V0B is read. In step 2, the voltage difference ΔV is calculated from (V0A-V0B) from the detection voltages V0A and V0B read in step 1.

In step 3, it is determined whether the voltage difference ΔV calculated in step 2 is larger than the intercept β 1 of the voltage difference characteristic line 41. When it is determined to be “YES” in step 3, it is determined that the unknown fuel is the heavy fuel (heavy mixed gasoline A), as is clear from FIG.

Therefore, when it is determined that the fuel is heavy fuel, the routine proceeds to step 4, where the heavy fuel voltage difference characteristic line 41 is selected,
In step 5, the MTBE concentration M is calculated according to the equation 2 based on the gradient α1 and the intercept β1 of the voltage difference characteristic line 41.

[0051]

[Equation 2]

On the other hand, if "NO" is determined in step 3, it is determined that the unknown fuel is the light fuel (light mixed gasoline B), as is clear from FIG.

Therefore, when it is determined that the fuel is light fuel, the routine proceeds to step 6, where the light fuel voltage difference characteristic line 42 is selected,
In step 7, the MTBE concentration M is calculated as shown in Equation 3 based on the gradient α2 and the intercept β2 of the voltage difference characteristic line 42.

[0054]

[Equation 3]

In step 8, the heavy and light gasoline G (fuel) and the MTBE concentration M are stored in the storage area 36A.
Remember.

As a result, in the control unit 36, the gasoline injection amount calculation process and the ignition timing built in the control unit 36 are controlled according to the property state (heavy, light and additive concentration) of the gasoline G stored in the storage area 36A. The control process can be performed accurately.

As described above, in the fuel property discriminating apparatus according to the present embodiment, the type of gasoline G and the concentration of the additive can be accurately calculated, whereby the property of gasoline G can be determined with extremely high accuracy. You can

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

Further, in this embodiment, the property of gasoline can be judged regardless of the gasoline temperature,
Unlike the prior art, it is not necessary to wait for the difference in temperature of the gasoline to occur, the properties of the gasoline can be determined early, and the engine control can be performed quickly.

Therefore, even when heavy gasoline is used in an engine in which the ignition timing of the engine is matched with the light gasoline, the ignition timing of the engine can be corrected to the ignition timing corresponding to the heavy gasoline. It is possible to solve the problem of incomplete combustion and the like due to the deviation of the exhaust gas, and to effectively reduce the harmful components in the exhaust gas.

In each of the above embodiments, step 2 in the program shown in FIG. 11 is a specific example of the signal difference calculating means, steps 3, 4, and 6 are specific examples of the property determining means, and step 5 is , 7 are specific examples of the concentration calculating means.

Further, the capacitance type sensor 15 is constructed such that the first electrode 18 and the second electrode 19 are orthogonal to each other, and the voltage applied to the electrodes 18 and 19 is adjusted to make the first electrode 18.
Although the signal detecting means and the second signal detecting means of No. 1 are configured, the present invention replaces the capacitance type sensor 15 with
The capacitance sensor is composed of a pair of parallel plate type electrode plates, different applied voltages VH and VL are alternately applied to the respective electrode plates, and characteristic lines (gradient and intercept) are calculated by the applied voltages VH and VL. Then, the property of gasoline may be determined.

Further, in the above embodiment, the additive is MTB.
Although the case of E has been described, the present invention is not limited to this, and an octaneization improving agent such as methanol or ethanol may be used as an additive. Known fuels are heavy mixed gasoline A which is a heavy and light fuel and light mixed gasoline B which is a light fuel.
However, the property may be determined by using the medium fuel and the heavy fuel, and the light fuel and the medium fuel as known fuels. And, as described above, when the additive and the fuel are changed, it goes without saying that the characteristics of FIGS. 9 and 10 change.

Further, the shape of the capacitance type sensor of the above embodiment is not limited to the shape of the capacitance type sensor 15 shown in FIGS. 2 to 6, but may be the shape shown in FIGS. 12 and 13.
In this shape, the entire radial dimension can be reduced by the amount that the connector 21 can be omitted, and the size can be reduced. The reference numerals in the drawings have a dash (') in order to correspond to the components of the capacitance type sensor 15 in the embodiment. In the capacitance type sensor 15 ', the lead wire is directly connected to the electrode plate 1 for connection with the external processing circuit 28.
8A ', 18B', 19A ', 19B' terminals 18A1
, 18B1 ', 19A1', 19B1 '.

[0065]

As described above in detail, in the present invention,
Collecting a plurality of signals with respect to the additive concentration by making the applied voltage different for the fuel in which the additive is mixed in the known two kinds of fuel with different known concentrations at the known concentration, Two characteristics corresponding to the signal difference for each known fuel are stored from this signal, the signal difference is detected for the unknown fuel, the fuel property is discriminated from this signal difference, and one of the two characteristics is determined. Select and establish additive concentration based on this property. As a result, the properties of the unknown fuel and the concentration of the additive can be calculated early, and high-precision engine control can be performed quickly. Then, the fuel injection amount and the ignition timing can be accurately controlled, and the driving performance of the vehicle can be effectively improved.

On the other hand, since the capacitance type sensor is constructed such that the first electrode and the second electrode are orthogonal to the fuel flow passage, a vector-like electric field can be applied in the fuel flow passage, Different signals can be detected depending on the applied voltage.

[Brief description of drawings]

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

FIG. 2 is a perspective view of a capacitance type sensor according to an embodiment.

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

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

FIG. 5 is an enlarged view of an essential part showing an enlarged part a in FIG.

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

FIG. 7 is a block diagram of a fuel property determination device according to an embodiment.

FIG. 8 is a specific circuit configuration diagram of the fuel property determination device shown in FIG. 7.

FIG. 9 is a characteristic diagram showing the detected voltage with respect to the MTBE concentration of known heavy and light gasoline.

FIG. 10 is a characteristic diagram showing a voltage difference with respect to the concentration of MTBE of known heavy and light gasoline.

FIG. 11 is a flowchart showing a fuel property determination process according to the embodiment.

FIG. 12 is a vertical cross-sectional view showing a modified example of the capacitance type sensor.

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

[Explanation of symbols]

15, 15 'Capacitance type sensor 18, 18' First electrode 19, 19 'Second electrode 25, 25' Fuel flow path 26 Detection processing circuit 27 Voltage applying device 28 Processing circuit 29 Oscillator 30, 32, 35 Filter circuit 31 attenuator circuit 33 differentiating circuit 34 arithmetic circuit (full-wave rectifying circuit + smoothing circuit) 36 control unit 36A storage area 41 (known heavy mixed gasoline) voltage difference characteristic line (signal difference characteristic) 42 (known light mixed gasoline) Voltage difference characteristic line (signal difference characteristic)

Claims (2)

[Claims] 1. A capacitance sensor, and a first sensor for detecting a signal corresponding to a relative permittivity of fuel from the capacitance sensor while a first voltage is applied to the capacitance sensor. A signal detecting unit and a second signal detecting unit for detecting a signal corresponding to the relative permittivity of the fuel from the capacitance type sensor while applying the second voltage to the capacitance type sensor; For a known fuel obtained by sequentially mixing two different types of fuel with an additive at a predetermined concentration, a signal for the additive concentration of each known fuel by the first signal detecting means and each known signal by the second signal detecting means The storage means for storing the signal difference characteristic with respect to the signal with respect to the additive concentration of each fuel as two characteristics showing different properties and the first signal detecting means are used to determine the relative permittivity of the unknown fuel. Detecting a signal and detecting the second signal A signal corresponding to the relative permittivity of the unknown fuel is detected using the output means, and a signal difference calculating means for calculating the signal difference, and the property of the unknown fuel based on the signal difference from the signal difference calculating means. Is determined and one of the two characteristics stored in the storage means is selected, and the unknown characteristic is determined based on the one characteristic selected by the characteristic determination means and the signal difference from the signal difference calculation means. A fuel property discriminating device comprising a concentration calculating means for calculating the additive concentration. 2. The capacitance type sensor has a fuel inlet and an outlet, and a fuel passage through which the fuel flows from the inlet to the outlet, and a fuel passage in the middle of the fuel passage. A pair of first electrodes provided so as to face each other with a fuel interposed therebetween, and a pair of first electrodes provided so as to face each other with a fuel flowing in the middle of the fuel flow path interposed therebetween and orthogonal to the first electrodes. The fuel property discriminating apparatus according to claim 1, wherein the fuel property discriminating apparatus comprises two electrodes.