DE10107892B4 - Method for identifying the encoder wheel error while driving - Google Patents

Abstract

für jedes Segment des Geberrades ein Fehlerwert aus der Verfahrensgleichung

ermittelt wird, wobei:
– φ ._e die gemessene, fehlerbehaftete Winkelgeschwindigkeit ist und der Fehlerwert δ' als differentieller Winkelfehler mit φ ._e = φ (1 – δ') definiert ist
– Θ das Massenträgheitsmoment der Kurbelwelle ist
– die kinetische Energie in einen über dem Kurbelwinkel konstanten, drehzahlabhängigen Anteil Ĕ und einen gasmomentabhängigen Anteil E_p zu E_kin = Ĕ + E_p aufgeteilt wird
– der Anteil Ĕ mit der über eine Kurbelwellenumdrehung gemittelten Winkelgeschwindigkeit

und dem mittleren Massenträgheitsmoment Θ zu

berechnet wird
– der Anteil E_p sich...A sensor for identifying the encoder wheel error of a crankshaft sensor wheel of an internal combustion engine, wherein a relative to the encoder wheel (1) fixed sensor (2) scans the segments of the encoder wheel (1) and from the recorded pulse sequence for each Geberradsegment an angular velocity is calculated, the error identification in the overrun mode Engine takes place and based on the kinetic energy of the crankshaft

For each segment of the sender wheel, an error value from the process equation

is determined, wherein:
- φ. _{e is} the measured, erroneous angular velocity and the error value δ 'as a differential angle error with φ. _e = φ (1-δ ') is defined
- Θ is the mass moment of inertia of the crankshaft
- The kinetic energy is divided into a constant over the crank angle, speed-dependent component Ĕ and a gas-dependent component E _p to E _kin = Ĕ + E _p
- The proportion Ĕ with the averaged over a crankshaft revolution angular velocity

and the mean moment of inertia Θ to

is calculated
- the proportion E _p is ...

Description

The The invention relates to a method for identifying the encoder wheel error according to the preamble of claim 1.

method for identification and compensation of the Geberradfehlers are in particular for accurate determination of the engine speed and for determining the position the crankshaft necessary. The engine speed affects a number of functions of the engine control. Mistakes or inaccuracies of Speed detection affect z. B. negative on the control loops idling and running restraint off. Furthermore, an accurate detection the angular velocity for crank-angle controlled injection systems (eg pump-nozzle injection systems) necessary, because from the instantaneous angular speed of the crankshaft Injection start and end are extrapolated.

Generally It is previously known to measure the speed and angular position of the crankshaft of internal combustion engines with the crankshaft rotating encoder wheel to arrange rotationally fixed, having markings or segments, the be scanned by a fixed sensor. Generally common metallic donor wheels z. B. with a 60-2 tooth pitch, by a Hall sensor or an inductive encoder are sampled, wherein the thus generated Pulse sequence evaluated and from it speed and angular position of the Crankshaft be calculated.

Previously known from the Scriptures DE 195 40 674 A1 an adaptation method for the correction of tolerances of a sensor wheel. Speed-dependent adaptation values are calculated for each transmitter wheel segment and stored in a characteristic diagram (toothed segment / speed range). The adaptation values are calculated from the measurement of the throughput times of the individual segments with respect to an average value over an entire revolution of the encoder wheel. The influence of the quantization error as well as the load, mass and gas moment are converted in a small signal approximation to fluctuations in the measured time duration between two segments. Segment-specific adaptation values are formed, the manufacturing tolerances of the encoder wheel, its mounting error and the influence of the speed-dependent mass and gas forces being included in the adaptation values.

The Adaptation values include the pitch error resulting from the encoder wheel, Error of centering during mounting and that caused by load and mass moments as well as the rotational nonuniformities resulting from the gas forces. The of the mass and gas forces originating, torques acting on the crankshaft affect at a non-uniform angular velocity but are not errors of the sender wheel. The influence of this Moments is also speed dependent, so for Different speed ranges each correction values are determined have to.

Of the Invention is based on the object from the manufacturing tolerances identify the encoder wheel and its mounting conditional errors and a segment-specific, speed-independent correction value for compensation to determine this error.

These Task is achieved by the features of claim 1 solved.

By the inventive method is for each segment a correction value based on the kinetic energy the crankshaft determined. The forces acting on the crankshaft Moments are inventively advantageous in a speed-dependent, over the Crank angle constant and a dependent on the crank angle proportion divided up. This separation allows the determination of the donor wheel and its cultivation Error (tooth pitch error and error of centering to the crankshaft) independently from the gas forces and load moments. It is thus a speed independent error value for each Segment can be determined.

Advantageously according to the invention, the functions G _suction , G _{exhaust gas} and G ₀ can be calculated from the engine geometry and the control times. The correction values for the encoder wheel segments can be determined by measuring the angular velocity and the pressure values.

_{Advantageously} according to the invention, the parameters G _suction , G _{exhaust gas} and G ₀ according to claim 2 be determined by measurements in different speed ranges. One can determine these parameters and thus the error value by solving a system of equations, wherein n equations are set up and solved for the determination of the n unknowns by n measurements. In the case of the basic method according to claim 1 equation measurements are required for each segment 4 to determine G _suction, G _{From gas,} G ₀ and δ '.

Becomes one or more of the parameters are determined by calculation, thus, correspondingly fewer measurements per segment are required.

ergibt, die durch drei Messungen in verschiedenen Drehzahlbereichen gelöst wird. Wird in der Gleichung die Funktion G_Saug entsprechend Anspruch 4 berechnet, können die Unbekannten E₀₃ und δ' durch zwei Messungen bestimmt werden.Advantageously according to claim 3, the exhaust gas back pressure p _{Ab gas} and the ambient pressure p ₀ kept constant, whereby the terms G _{Ab gas} · p _{exhaust gas} and G ₀ · p ₀ TO E ₀₃ = G _{from gas} · p _{exhaust as} + G ₀ · p ₀ are summarized and the process equation to

results, which is solved by three measurements in different speed ranges. If the function G _suction according to claim 4 is calculated in the equation, the unknowns E ₀₃ and δ 'can be determined by two measurements.

mit zwei Messungen ermittelt.In an advantageous embodiment of the inventive method according to claim 5, the intake manifold pressure p _suction , the exhaust back pressure p _{exhaust gas} and the ambient pressure p ₀ kept constant, the G terms to E ₀₁₃ = G _suction · p _suction + G _exhaust · P _{Ab gas} + G ₀ · p ₀ , since these appear as constants in the system of equations. The encoder wheel error δ 'is then through the

determined with two measurements.

In a further advantageous embodiment according to claim 6, the crank angle periodic secondary moments, as described for. B. from the valve train or the injection elements, included in the calculation of the kinetic energy of the crankshaft. The alternating component of the energy for the secondary engine is calculated from the alternating component M ~ _{Neb en of} the secondary torque M _{Neb en} by integration over the crank angle φ: e Neb s = ∫M ~ Neb s dφ

The general process equation taking into account the secondary moments is then

The size E _Neb is _en a parameter and therefore does not increase the number of unknowns in the process equation.

The extension of the method to the equation E _side is possible in all of the embodiments (claims 1-5), the accuracy of calculation of Geberradfehlers thereby increased.

Further Details of the invention are described in the drawing with reference to FIG illustrated embodiments described.

in this connection shows:

1 a schematic representation of a structure for carrying out the method according to the invention,

2 a flow chart for carrying out the method.

die Winkelgeschwindigkeit des Motors berechnet. Die Zahnteilung Δz ist aufgrund von Fertigungstoleranzen nicht konstant. Zusätzlich wirken sich Anbaufehler oder Beschädigungen des Geberrades (Deachsierung und Höhenschlag) als Fehler auf die Winkelgeschwindigkeit aus. Weiterhin können von der Kurbelwinkelstellung abhängige, asymmetrische Streufelder die Winkelgeschwindigkeit verfälschen. Diese Fehler verschieben die Nulldurchgänge des Signals um einem Fehlerwinkel Δφ. 1 shows a possible structure for carrying out the method according to the invention in a schematic diagram. A donor wheel 1 with circumferentially distributed markings, preferably toothed segments - not shown - is non-rotatably connected to a crankshaft of an internal combustion engine - not shown -, wherein a relative to the encoder wheel 1 fixed sensor 2 the marks on the sender wheel 1 monitored and generates an equivalent pulse train, which on the input side to the sensor 2 connected evaluation unit 3 is applied. It is the time .DELTA.t between two zero crossings of the pulse train, which represents the time between two consecutive tooth segments, measured with a timer module and with the tooth pitch .DELTA.z of the encoder wheel is according to formula

the angular velocity of the engine is calculated. The tooth pitch Δz is not constant due to manufacturing tolerances. In addition, mounting errors or damage to the sender wheel (alignment and radial runout) have an effect on the angular velocity. Furthermore, depending on the crank angle position, asymmetric stray fields can distort the angular velocity. These errors shift the zero crossings of the signal by an error angle Δφ.

ergibt. Der differentielle Geberradfehler ist mit

definiert, wobei durch algebraisches Umformen von (2) und Einsetzen von (3) die fehlerbehaftete Winkelgeschwindigkeit

lautet und der differentielle Geberradfehler δ' durch das erfindungsgemäße Verfahren berechnet wird. Die korrekte Winkelgeschwindigkeit φ . ergibt sich nach

As a result, the control unit measures an erroneous angular velocity, which is thus too

results. The differential encoder wheel error is with

by algebraically transforming (2) and substituting (3) the errored angular velocity

is and the differential encoder wheel error δ 'is calculated by the method according to the invention. The correct angular velocity φ. arises after

aufgestellt, wobei Θ das Massenträgheitsmoment der Kurbelwelle ist, das aufgrund der Kurbelkinematik eine Funktion des Kurbelwinkels ist. Diese Funktion wird mit den Massen und Abmessungen von Kurbelwelle, Kolben und Pleuel berechnet und steht somit als bekannter Parameter zur Verfügung. Durch Einsetzen der fehlerbehafteten Winkelgeschwindigkeit φ ._e nach (4) ergibt sich die kinetische Energie der Kurbelwelle zu

To calculate the encoder wheel error, the energy conservation law for the kinetic energy of the crankshaft becomes

where Θ is the mass moment of inertia of the crankshaft, which is a function of the crank angle due to the crank kinematics. This function is calculated with the masses and dimensions of crankshaft, piston and connecting rod and is therefore available as a known parameter. By substituting the erroneous angular velocity φ. _e according to (4) results in the kinetic energy of the crankshaft

The kinetic energy E _kin can be divided into a constant over the crank angle, but speed-dependent component Ĕ and a gas-torque-dependent component E _p , from which e kin = Ĕ + E p (8th) results.

und dem mittleren Massenträgheitsmoment Θ nach

berechenbar.The speed-dependent component Ĕ is with the averaged over a crankshaft revolution Winkelge speed

and the mean moment of inertia Θ to

predictable.

The proportion E _p is due to the periodic gas exchange, compression and combustion forces depending on the intake manifold pressure and the combustion process.

There is no combustion in the thrust, so there are no combustion forces. The energy contributions of charge exchange, compression and expansion can be divided into a proportion proportional to the intake manifold pressure p _{suction, a} proportion proportional to the exhaust gas back pressure p _{exhaust gas} and a proportion dependent on the ambient pressure p ₀ . This results in e p = G Suction · p Suction + G Abg as · p exhaust + G 0 · p 0 (10)

The functions G _suction , G _exhaust and G ₀ are functions of the crank angle, depending on the constructive dimensions of the crank mechanism and the valve timing.

The total kinetic energy E _kin is described by the following formula e kin = Ĕ + G Suction · p Suction + G exhaust · p Abg as + G 0 · p 0 (11).

Substituted in (7), the general equation of the method results

Out This general process equation allows several sub-processes derive, which in terms of the boundary conditions and the computational effort differ.

Done for the general method no assumptions or requirements regarding G _{suction, exhaust} G and G _0, which the general method equation, the following four unknowns G _suction, G _{From gas,} G includes ₀ and δ '. To solve this equation, the instantaneous velocity φ must be determined for each crank angle. _e as well as the parameters p _suction , p _exhaust and p ₀ are measured for each tooth at least four revolutions. The data of the four measurements form a system of equations with four equations.

For the measured four turns the mean velocities differ from each other independent To get equations. By loosening of the equation system can for each angular position is an associated one differential encoder wheel error δ 'are determined.

The functions G _suction , G _exhaust and G ₀ result from the engine geometry and the valve timing, they are thus calculable as parameters of the general process equation. For every explicit calculation of a G-function, the number of determinate equations and thus the number of necessary measurements is reduced by one. If all parameters are calculated and the pressure values are measured, one measured value per angular position is sufficient.

During the measurements of the exhaust back pressure p _exhaust and the ambient pressure p constant _0, the terms G _{from gas} · p _{from gas} and G ₀ · p ₀ can e 03 = G exhaust · p exhaust + G 0 · p 0 (13) be summarized. The process equation is then:

For the three unknowns G _suction , E ₀₃ and δ ', three measurements must be carried out analogously to the general method. The function G _suction can be calculated again, so that only the unknowns E ₀₃ and δ 'remain and two determinations are sufficient.

If, for the measurements, the intake manifold pressure p _suction , the exhaust back pressure p _{exhaust gas} and the ambient pressure p ₀ are kept constant, then the G terms may increase e 013 = G Suction · p Suction + G exhaust · p exhaust + G 0 · p 0 (15) summarized so that starting from (12) the process equation

2 shows a flowchart for performing the method in a block diagram. The illustrated method shows a possible embodiment, wherein the differential encoder wheel error by a system of equations with 2 unknown z. B. according to (16) or claim 5 is determined. The detection of the Geberradfehlers occurs while driving the vehicle. As the next condition for carrying out the method, overrun operation is checked. The method is performed only in overrun to eliminate the influence of the combustion forces caused by the combustion on the crankshaft.

at detected overrun is checked as a further condition, whether boost pressure and EGR controllers operate in measuring mode, d. H. whether the pressure readings needed to solve the equation can be determined or checked for their constant value. Below is the Stay checked in overrun mode and at Below a first measuring speed, the measurement of the segment-specific Throughput times or the angular velocities determined therefrom started and for saved another calculation. Is the vehicle located continue in overrun and a second measuring speed is exceeded, the second speed profile is recorded. Through the measuring points in different speed ranges can have two independent equations to the solution of the equation system are set up. Stands for each sender wheel segment after loosening of the system of equations the differential encoder wheel error δ 'according to equation (3) to disposal, from which equation (5) the correct angular velocity φ. determined can be.

LIST OF REFERENCE NUMBERS

Claims (6)

Method for identifying the sensor wheel error of a crankshaft sensor wheel of an internal combustion engine, wherein a relative to the sender wheel ( 1 ) fixed sensor ( 2 ) the segments of the sender wheel ( 1 ) and from the recorded pulse train for each Geberradsegment an angular velocity is calculated, the error identification is carried out in the overrun of the engine and based on the kinetic energy of the crankshaft

For each segment of the sender wheel, an error value from the process equation

is determined, where: - φ. _{e is} the measured, erroneous angular velocity and the error value δ 'as a differential angle error with φ. _e = φ (1-δ ') is defined - Θ the mass moment of inertia of the crankshaft is - the kinetic energy in a constant over the crank angle, speed-dependent component Ĕ and a gas-dependent component E _{p is divided} into E _kin = Ĕ + E _p - Proportion Ĕ with the angular velocity averaged over one crankshaft revolution

and the mean moment of inertia Θ to

is calculated - the proportion E _p is the sum of a to the intake manifold pressure p _{sow g} , the exhaust back pressure p _{exhaust gas} and the ambient pressure p ₀ proportional proportion e p = G Suction · p Suction + G exhaust · p exhaust + G 0 · p 0 results. A method according to claim 1, characterized in that the calculable for determining the error value from the engine parameters parameter G _Saug , G _exhaust , G ₀ individually or jointly by solving a system of equations with n unknowns by n-fold measurement in different speed ranges are determined. A method according to claim 1, characterized in that exhaust back pressure p _{exhaust gas} and the ambient pressure p ₀ are kept constant. A method according to claim 3, characterized in that the function G _{suction is} calculated and the unknowns E ₀₃ and δ 'are determined by two measurements, wherein E ₀₃ = G _{Ab gas} · p _{Ab gas} + G ₀ · p ₀ . A method according to claim 1, characterized in that the intake manifold pressure p _suction , the exhaust back pressure p _{exhaust gas} and the ambient pressure p ₀ are kept constant. Method according to one of the preceding claims, characterized in that the energy portion of crank angle periodic Nehenmomente from the AC component M _{Neb en} the secondary torque M _Beside by integration over the crank angle φ: E _{Neb en} = ∫M ~ _{Neb en} dφ calculated and enters into the process equation as follows :