CN100460821C - Engine throttle position sensing method and sensor - Google Patents

Abstract

The invention relates to a sensing method of engine's throttle plate place .It uses two parallel plate capacitor separately used as measure capacitance and reference compensation capacitor .One wafer of the measure capacitance is fixed connected to throttle plate's rotating shaft , the other wafer is fixed installed on the shell matrix of the capacitance on the throttle plate , and two wafers keep the same distance in axial direction .Two wafers forming the capacitance's effective area changes with the jaw opening of the throttle plate .The reference compensation capacitor and the measure capacitor are installed in the same environment ,and the former capacitor compensates the latter one gain accurate change value of the measure capacitor .Measure the linear relationship between the changing value and rotating angle of capacitor , through circuit processing ,then obtain the accurate angle of unlocking the throttle plate to realize the measurement of the place of throttle plate .The invention can realize high resolution and high degree of accuracy measurement under large scale , and it's useful to extend the sensor's useful time .Its structure is simple ,and it is inexpensive ,the requirement of its craft is not high .

Description

A kind of engine throttle position sensing method and sensor

Technical field

The present invention relates to the position sensing technology, be specifically related to position sensing engine air throttle apertures such as automobile, motorcycles.

Background technology

The engine throttle position sensing device is an important sensor of electronic throttle and automobile electronic fuel oil jet system.It can in time send the position signalling of air throttle to engine management system ECM, makes ECM can correctly know the automobile aperture of air throttle and throttle opening situation about changing in the process of moving.ECM is according to this throttle signal that obtains, can accurately determine fuel supply volume how much or according to the size of the aperture of the situation of automobilism and regulating working conditions air throttle.As seen, throttle position sensor is as one of key components of automobile electronic fuel oil jet system and electronic throttle, and its normal, stable work can make automobile obtain good power performance and gasoline is fully burned, and reduces pollutant discharge amount.

Throttle position sensor commonly used at present can be divided three classes according to principle:

1, adjustable resistance partial pressure type

The sensor of this form adopts an annular carbon resister that is fixed on the throttle body usually, forms with the brush that is fixed on the air throttle rotation axis.When throttle opening changes, corresponding the changing in the position of brush on annular carbon resister, thus changed the output voltage of tap place.

Adjustable resistance formula throttle position sensor principle is simple, easy to use.But, need the contact of contact component under situations such as vibration, temperature variation good, and have excellent abrasive because sensor internal has relative motion.Thereby adjustable resistance formula throttle position sensor requires very highly on material and manufacture craft, thereby costs an arm and a leg.

2, induction

This class sensor adopts electromagnetic induction principle, promptly when a part of conductor of electromagnetic induction closed circuit is done cutting magnetic line movement in magnetic field, just produces induction current in the conductor.This class sensor construction more complicated, thereby price is more expensive.

3, hall principle formula

Be arranged in the conductor in magnetic field, apply external impressed current in direction perpendicular to magnetic field, so then with the magnetic field direction vertical with applying external impressed current on can to produce another voltage be Hall voltage.Sensor based on Hall effect has outstanding frequency response characteristic, but the temperature drift of output is very big, and is bigger without the temperature correction error, and needs a stable external current source.In addition, the structure of Hall element is relatively complicated, and price is very expensive.

Summary of the invention

The present invention is directed to the throttle position sensor relative merits separately of three common in the market class different principle, propose a kind of inside contactless throttle position sensing method and sensor based on parallel flat tunable capacitor principle.

The inventive method has adopted parallel flat electric capacity, and referring to Fig. 1, its principle is as follows:

Two is that its appearance value of two parallel plates electric capacity C of S is at a distance of D, useful area:

$C=\frac{\mathrm{\&epsiv;<figure-callout\; id="4"\; label="S"\; filenames="C200710078633E00083.png,C200710078633E00092.png"\; state="\{\{state\}\}">S</figure-callout>}}{4\mathrm{\&pi;kD}}---\left(1\right)$

Wherein: ε-specific inductive capacity

K-dielectric constant

From formula (1) as can be seen, dielectric constant ε, when dielectric constant k is constant (material of making electric capacity is certain), if the distance D of two-plate is a constant, capacitance is directly proportional with useful area S; If useful area S is constant, change the space D between the pole plate, then appearance value and space D are inversely proportional to.

Thereby, change the position change of air throttle the change of parallel flat electric capacity useful area S or space D into by certain mode, just can obtain the position of air throttle so by the appearance value of measuring electric capacity.

Based on this, the mode that the present invention can select to change useful area or change dull and stereotyped spacing realizes the sensing of throttle position.

The throttle position sensing method that the present invention proposes is as follows:

Adopt a parallel flat electric capacity as measuring electric capacity, this measurement electric capacity is an adjustable capacity plate antenna, the pole plate and the air throttle rotating shaft of this measurement electric capacity are fixed, and with the air throttle coaxial rotation, another pole plate is fixed in the electric capacity housing base that is installed in throttle body, two pole plates keep axial distance constant, and the useful area of two blocks of pole plate formation electric capacity changes with the aperture of air throttle, and the appearance value and the useful area of electric capacity are linear.

The parallel flat electric capacity that the appearance value remains unchanged when adopting another operate as normal is as the reference building-out capacitor, its capacitance equates or proportional relation with the maximum capacitor value that above-mentioned measurement electric capacity can reach, should be installed in the same environment with reference to building-out capacitor and measurement electric capacity, by measuring this variation, obtain the change amount of environment to capacitor's capacity with reference to building-out capacitor appearance value.

With measuring electric capacity capacitance that records and the environment that obtains by the reference building-out capacitor change amount of capacitance is handled through back-end circuit, get final product compensation temperature and other environmental factor etc. to measuring the influence of capacitance, can obtain the accurate angle value that air throttle is opened, realize the measurement of air throttle of car position.

In the actual fabrication process, the dielectric on the described adjustable parallel capacity plate antenna pole plate adopts the fan ring structure, and the ring radius was all identical with the outer shroud radius in two fan ring plates were dielectric.

Get method as can be known from foregoing description of the present invention, it adopted a pole plate in the electric capacity housing base that is fixedly mounted on throttle body and be fixed on the air throttle rotation axis and form parallel flat electric capacity with another pole plate that throttle plate pin rotates synchronously, when throttle opening changes, the pole plate that is fixed on the air throttle rotation axis rotates thereupon, useful area between the two dull and stereotyped dielectrics changes, as shown in Figure 2, and the D apart of the two, interior ring radius L, outer shroud radius L ₁, the area that then overlaps between the two is:

$S=\frac{(\mathrm{\&pi;}{{\mathrm{<figure-callout\; id="1"\; label="L"\; filenames="C200710078633E00092.png"\; state="\{\{state\}\}">L</figure-callout>}}_1}^2-\mathrm{\&pi;}{L}^2)\mathrm{\&theta;}}{2\mathrm{\&pi;}}=\frac{({{\mathrm{<figure-callout\; id="1"\; label="L"\; filenames="C200710078633E00092.png"\; state="\{\{state\}\}">L</figure-callout>}}_1}^2-L^2)\mathrm{\&theta;}}{2}---\left(2\right)$

Can calculate the appearance value C of electric capacity according to formula (1):

$C=\frac{\mathrm{\&epsiv;<figure-callout\; id="4"\; label="S"\; filenames="C200710078633E00083.png,C200710078633E00092.png"\; state="\{\{state\}\}">S</figure-callout>}}{4\mathrm{\&pi;kD}}=\frac{({{\mathrm{<figure-callout\; id="1"\; label="L"\; filenames="C200710078633E00092.png"\; state="\{\{state\}\}">L</figure-callout>}}_1}^2-L^2)\mathrm{\&epsiv;\&theta;}}{8\mathrm{\&pi;kD}}=\mathrm{A\&theta;}---\left(3\right)$

Wherein,

$A=\frac{({{\mathrm{<figure-callout\; id="1"\; label="L"\; filenames="C200710078633E00092.png"\; state="\{\{state\}\}">L</figure-callout>}}_1}^2-L^2)\mathrm{\&epsiv;}}{8\mathrm{\&pi;kD}}---\left(4\right)$

When structure (is distance D, L, L necessarily _lBe constant), during material certain (being that dielectric constant k, DIELECTRIC CONSTANT are constant), A is a constant in the formula 4, promptly capacitance is directly proportional with the angle theta of the two.Also promptly, adopt the fixed sturcture of the capacitance structure preparation shown in Fig. 2 and the capacity plate antenna of immobilization material, its appearance value is directly proportional with between the two angle, thereby just can measure the aperture of air throttle by the appearance value of measurement electric capacity.

Because electric capacity is subject to the influence of other factorses such as temperature and environment, single this measurement electric capacity that relies on can't obtain angle signal accurately, Given this, in order to make measurement electric capacity be subjected to the influence of other factorses such as temperature and environment to reduce to minimum, the inventor considers that the electric capacity that adopts identical material and technology is as the reference building-out capacitor, this gets capacitance with reference to building-out capacitor and equates or proportion relation with measurement electric capacity maximum capacitor value, be in the same environment with reference to building-out capacitor and measurement electric capacity, by measuring this variation, obtain the change amount of environment to capacitor's capacity with reference to building-out capacitor appearance value; With measuring electric capacity capacitance that records and the environment that obtains by the reference building-out capacitor change amount of capacitance is handled through back-end circuit, get final product compensation temperature and other environmental factor etc. to measuring the influence of capacitance, can obtain the accurate angle value that air throttle is opened, realize the measurement of air throttle of car position.

Based on the above method, the applicant has proposed a kind of specific implementation structure of position transducer on engine air throttle that this method forms, and it is measured electric capacity, one by one and forms with reference to building-out capacitor and treatment circuit.

Described measurement electric capacity is an adjustable parallel capacity plate antenna, the wherein pole plate and the air throttle rotating shaft of this measurement electric capacity are fixed, and with the air throttle coaxial rotation, another piece pole plate is installed on the electric capacity housing base of throttle body, two coaxial installations of pole plate also keep axial distance constant.

Described is the parallel flat electric capacity that capacitance remains unchanged when the operate as normal with reference to building-out capacitor, and its capacitance equates or proportional relation with the maximum capacitor value of above-mentioned measurement electric capacity, this with reference to building-out capacitor with measure electric capacity and be installed in the same environment.

Described measurement electric capacity and with reference to building-out capacitor respectively by output line connection processing circuit.

As seen, advantage of the present invention is fairly obvious:

At first, it adopts adjustable capacity plate antenna principle to realize the sensing of air throttle rotational angle, high resolving power, high-acruracy survey under having realized on a large scale;

The second, it is a kind of non-cpntact measurement, has realized the characteristics of survey sensor sensing unit on-mechanical contact, helps prolonging the serviceable life of sensor;

The 3rd, its adopts with reference to building-out capacitor and carries out the compensation to the capacitance influence of temperature and other environmental factor, and having eliminated factor such as environment must influence, and has improved the degree of accuracy of measuring;

The 4th, it is simple in structure, and technological requirement is not high, low price.

Description of drawings

Fig. 1 is a parallel flat tunable capacitor principle schematic;

Fig. 2 is a kind of implementation of throttle position sensor;

Fig. 3 is the mounting structure synoptic diagram of this sensor;

Fig. 4 is a kind of concrete mount scheme figure of this sensor;

The circuit diagram of Fig. 5 capacitance measurement.

Embodiment

Referring to Fig. 3 and Fig. 4, the motor car engine throttle position sensor is measured electric capacity, one by one and is formed with reference to building-out capacitor and treatment circuit.Measuring electric capacity 1 is an adjustable parallel capacity plate antenna, for the ease of processing of circuit, can adopt fan ring plate dielectric, and as shown in Figure 2, the ring radius was all identical with the outer shroud radius in two fan ring plates were dielectric.This pole plate 1A who measures electric capacity 1 is fixedlyed connected with air throttle rotating shaft 3, and with air throttle 4 coaxial rotation, another pole plate 1B is fixedly mounted in the electric capacity housing base 5 that is fixed on the throttle body 6, also the maintenance axial distance is constant in two coaxial installations of pole plate.The constant parallel flat electric capacity of capacitance when being an operate as normal with reference to building-out capacitor 2, its capacitance equates or proportion relation with the maximum capacitor value of above-mentioned measurement electric capacity, this is installed in the same environment with reference to building-out capacitor and measurement electric capacity, as shown in Figure 4, be fixedly mounted in the electric capacity housing base 5, two electric capacity are in the same environment.Measure electric capacity 1 and pass through output line connection processing circuit respectively, measuring-signal is handled with reference to building-out capacitor 2.

Measuring-signal is handled can adopt existing techniques in realizing, below enumerates a kind of disposal route, sees Fig. 5.CAV424 among Fig. 5 is a special chip of measuring electric capacity, C _X1For measuring electric capacity, C _X2Be the reference building-out capacitor.The CAV424 principle of work is such, and one by capacitor C _OSCThe reference oscillator of determining frequency is being controlled the integrator of the constant symmetric construction identical with the cycle of two phase places.The amplitude of these two integrators passes through capacitor C _X1And C _X2Determine.Relatively the voltage amplitude difference of two integrators just can draw capacitor C _X1And C _X2Relative capacitance variations difference, this differential signal converts d. c. voltage signal and through the output of the adjustable differential signal output stage of output promptly 5. and the V 6. to by a secondary low-pass filter _DIFF, promptly obtain accurate capacitance.Because this capacitance is directly proportional with the opening angle θ of air throttle, can obtain accurate angle changing value according to following formula:

$C=\frac{\mathrm{\&epsiv;<figure-callout\; id="4"\; label="S"\; filenames="C200710078633E00083.png,C200710078633E00092.png"\; state="\{\{state\}\}">S</figure-callout>}}{4\mathrm{\&pi;kD}}=\frac{({{\mathrm{<figure-callout\; id="1"\; label="L"\; filenames="C200710078633E00092.png"\; state="\{\{state\}\}">L</figure-callout>}}_1}^2-L^2)\mathrm{\&epsiv;\&theta;}}{8\mathrm{\&pi;kD}}=\mathrm{A\&theta;}---\left(3\right)$

Wherein, $A=\frac{({{\mathrm{<figure-callout\; id="1"\; label="L"\; filenames="C200710078633E00092.png"\; state="\{\{state\}\}">L</figure-callout>}}_1}^2-L^2)\mathrm{\&epsiv;}}{8\mathrm{\&pi;kD}}---\left(4\right)$

D is for measuring the distance between electric capacity two flat plate, and L is for measuring ring radius in the dull and stereotyped dielectric of electric capacity, L ₁For measuring the dull and stereotyped dielectric outer shroud of electric capacity radius, k is a specific inductive capacity of measuring capacitor dielectric for dielectric constant, the ε that measures capacitor dielectric, and θ is for measuring the angle that electric capacity rotates with throttle plate pin.

Claims (3)

1. motor car engine throttle position sensing method is characterized in that:

Adopt a parallel flat electric capacity as measuring electric capacity, this measurement electric capacity is an adjustable parallel capacity plate antenna, a pole plate measuring electric capacity is fixedlyed connected with the air throttle rotating shaft, and with the air throttle coaxial rotation, another piece pole plate is fixed in the electric capacity housing base that is installed on the throttle body; Axial distance between two pole plates remains unchanged, and the useful area that two pole plates form electric capacity changes with the aperture of air throttle, and the capacitance and the useful area of electric capacity are linear;

Another parallel flat electric capacity that adopts identical material and technology is as the reference building-out capacitor, its capacitance equates or proportional relation with the maximum capacitor value that above-mentioned measurement electric capacity can reach, should be installed in the same environment with reference to building-out capacitor and measurement electric capacity, by measuring the variation of described capacitance with reference to building-out capacitor, obtain the change amount of environment to capacitance;

To measure electric capacity capacitance that records and the environment that obtains by the reference building-out capacitor to the change amount of capacitance processing of circuit through the rear end, compensation temperature and other environmental factor are to measuring the influence of capacitance, obtain the accurate capacitance variations value of measuring, according to measuring capacitance variations value and the linear relationship of measuring the electric capacity rotational angle, through processing of circuit, promptly obtain the accurate angle value that air throttle is opened, realize the measurement of air throttle of car position.

2. motor car engine throttle position sensor is characterized in that: it is measured electric capacity, one by one and forms with reference to building-out capacitor and treatment circuit;

Described measurement electric capacity is an adjustable parallel capacity plate antenna, the wherein pole plate and the air throttle rotating shaft of this measurement electric capacity are fixed, and with the air throttle coaxial rotation, another piece pole plate is fixed in the electric capacity housing base that is installed on the throttle body, the axial distance between two pole plates remains unchanged;

Described is a parallel flat electric capacity with reference to building-out capacitor, and its capacitance equates or proportional relation with the maximum capacitor value of above-mentioned measurement electric capacity during operate as normal, and this is installed in the same environment with reference to building-out capacitor and measurement electric capacity;

Described measurement electric capacity and with reference to building-out capacitor respectively by output line connection processing circuit.

3. motor car engine throttle position sensor according to claim 2 is characterized in that: the dielectric on the described adjustable parallel capacity plate antenna pole plate adopts the fan ring structure, and the ring radius was all identical with the outer shroud radius in two fan ring plates were dielectric.

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