EP1792057B1 - Method for positional determination for an ec motor - Google Patents

Description

The invention relates to a method for determining the position of an EC motor for a device for adjusting the rotational angle position of the camshaft of a reciprocating internal combustion engine relative to the crankshaft, wherein the crankshaft via a variable speed drive is in driving connection with the camshaft, which is a three-shaft transmission with a crankshaft fixed drive shaft, a camshaft-fixed output shaft and an adjusting shaft is formed, which is in driving connection with the EC motor, wherein the rotor of the EC motor offset in the circumferential direction to each other, alternately magnetized in opposite directions magnetic segments, wherein for determining the position of the rotor relative to the Stator of the EC motor, a measuring device is provided, which has circumferentially offset from each other on the stator magnetic field sensors, which are arranged such that they at a rotational movement of the rotor relative to the stator with error-free measurement of a digital Produce sensor signal that undergoes an order of sensor signal states that occurs at least two times per mechanical revolution of the rotor.

Such a method for determining the position of the rotor of an EC motor relative to its stator is known in practice. So revealed document EP0918142 A2 such a procedure. A similar procedure is taken from the document US2004 / 083999 A1 , In this case, the EC engine is part of a camshaft adjusting device, by means of which the rotational angle position of the camshaft of a reciprocating internal combustion engine is adjustable relative to the crankshaft. The camshaft adjusting device has an adjusting gear, which is designed as a three-shaft gear, with the drive shaft a rotatably mounted relative to the camshaft camshaft gear is rotatably connected, which is in driving connection via a drive chain with a crankshaft gear. An output shaft of the variable speed drive is in drive connection with the camshaft and an adjusting shaft with the EC motor. When the drive shaft is stationary, there is a gear ratio predetermined by the adjusting gear between the adjusting shaft and the output shaft, the so-called stationary gear ratio. If the adjusting rotates, increases or decreases depending on the direction of rotation of the adjusting relative to the camshaft gear, the phase angle of the camshaft relative to the crankshaft. Compared to an internal combustion engine, which is operated with a constant phase position, by adjusting the phase position better cylinder filling of the internal combustion engine can be achieved, whereby fuel can be saved, the pollutant emissions can be reduced and / or the output line of the internal combustion engine can be increased.

The position of the rotor relative to the stator is measured by means of a measuring device which has three Hall sensors fixedly connected to the stator, which are distributed over the circumference of the stator. The Hall sensors are each flooded in a rotational movement between the stator and the rotor of the magnetic field of the just over them advancing magnetic segment of the rotor. The magnetic fields of the magnetic segments induce electrical voltages in the Hall sensors, which can be used as a digital sensor signal for a position measurement. In the position measurement, a position measurement signal is first set to a start value and then the rotor is rotated relative to the stator, wherein the position measurement signal is tracked at each occurrence of a state change of the sensor signal. The position measurement signal is fed to a drive device, which energizes the individual phases of the winding via an output stage such that a magnetic traveling field is formed between the stator and the rotor, which drives the rotor. However, in practice, the EC motor and the measuring device are exposed to interference which, for example, can reach the measuring device via power supply lines and cause errors in the position measuring signal there. On the one hand, it may happen that one or more state changes in the tracking of the position measurement signal are ignored due to a fault. On the other hand, it is also possible that too many state changes are detected when tracking the position measurement signal. In both cases, a deviation of the position measurement signal from the actual position of the rotor occurs, so that it is not energized correctly. This can cause torque losses, uneven engine running and errors in adjusting the rotational position of the camshaft relative to the crankshaft.

It is therefore an object to provide a method of the type mentioned, which allows a precise adjustment of the rotational position of the camshaft even when interference occurs.

This object is achieved with the features of claim 1.

According to the invention, the angle of rotation of the crankshaft is detected and used to check a derived from the digital sensor signal position measurement signal. If, during the check, a deviation is detected which exceeds a predefined limit value, a coarse correction of the position measuring signal is carried out. In the coarse correction, a value is preferably added to or subtracted from the position measurement signal which corresponds to the path or an integral multiple of the path of a full rotation of the rotor divided by the number of magnetic field sensors. If the order The sensor signal values assigned to the position measurement values do not match the stored sequence of the sensor signal states, a fine correction of the position measurement signal is also performed in which the sensor signal is restored in accordance with the stored sequence of sensor signal states and the position measurement signal is corrected accordingly. Advantageously, the method enables a reconstruction of the position measurement signal both when small amounts occur (eg, less than half the number of stored sensor signal states) and when larger errors occur. The claim 1 is to be understood that in the inventive method, the steps e) and f) can also be interchanged with the steps g) and h), ie it can also be performed first the fine correction and then the coarse correction.

In an advantageous embodiment of the invention, a crankshaft rotation angle measurement time is detected for each of the first and second crankshaft rotation angles, wherein from the first and second crankshaft rotation angles, the time difference between the crankshaft rotation angle measurement times and the time interval between the crankshaft rotation angle measurement time of the second crankshaft rotation angle and a reference time An estimate of the angle of rotation that the crankshaft has at the reference instant is extrapolated, and wherein the coarse correction and / or the fine correction with this estimated value is performed as a new second rotational angle measured value. The correction of the second position measured value is carried out at a reference time, which is temporally after the crankshaft rotation angle measuring times. In this case, it is possible, in particular, for the reference instant to be asynchronous with respect to a clock kar, n with which the crankshaft rotation angle measurement values are detected. Nevertheless, due to the extrapolation of the new second rotational angle measurement with a uniformly moving rotor, a high precision of the position measurement signal is achieved.

It is advantageous if in each case a position measuring time is detected for the first and second position measured value, if from the first and second position measurement, the time difference between the Lagemesswert measuring times and the time interval between the Lagemesswert measuring time of the second position measured value and the reference time an estimated value for the value that the position measurement signal has at the reference instant is extrapolated, and when the coarse correction with this estimated value is performed as a new second position measured value. By this measure, an even greater accuracy in determining the position can be achieved. The reference time may be asynchronous to a clock used to acquire the position readings.

In a preferred embodiment of the invention, the reference time is generated at a predetermined angular position of the camshaft. This can be achieved, for example, by monitoring the position of the camshaft with the aid of a camshaft sensor and, when passing through the predetermined camshaft rotational position, triggering an interrupt in a control unit in which the position measurement signal is checked and, if necessary, restored.

It is advantageous if the position measurement values are differentiated to form angular velocity values. The corresponding angular velocity signal may be used to determine the estimates and / or to control the speed of the EC motor.

In an advantageous embodiment of the invention, in order to compensate for tolerances of the magnet segments and / or magnetic field sensors for the individual magnet segment sensor combinations, a correction value is determined and stored, the position measurement values and / or angular velocity values being corrected with the correction values. As a result, in particular positioning tolerances of the magnetic segments and / or magnetic field sensors can be compensated. The inventive method then allows even greater precision in determining the position of the rotor relative to the stator.

Fig. 1:

eine schematische Darstellung eine Kurbelwellen-Nockenwellenanordnung eines Hubkolben-Verbrennungsmotors, die eine Verstellvorrichtung zum Verändern der Drehwinkellage der Nockenwelle relativ zur Kurbelwelle aufweist,

Fig. 2

eine schematische Stirnseitenansicht des Rotors eines EC-Motors, bei der auch die an dem Stator angeordneten Magnetfeld-Sensoren zu sehen sind,

Fig. 3

eine graphische Darstellung eines mit Hilfe einer Lagemesseinrichtung erfassten Sensorsignals, und

Fig. 4

eine graphische Darstellung des tatsächlichen Drehwinkels des EC-Motor-Rotors, wobei die Stellen, an denen Magnetfeldsensor-Pulse auftreten, im Drehwinkelverlauf markiert sind, wobei auf der Abszisse die Zeit und auf der Ordinate der Drehwinkel aufgetragen ist.

An exemplary embodiment of the invention is explained in more detail below with reference to the drawing. Show it:

Fig. 1:

1 is a schematic representation of a crankshaft camshaft arrangement of a reciprocating internal combustion engine having an adjusting device for changing the rotational angle position of the camshaft relative to the crankshaft,

Fig. 2

a schematic end view of the rotor of an EC motor, in which the arranged on the stator magnetic field sensors are seen,

Fig. 3

a graphical representation of a detected by means of a position measuring sensor signal, and

Fig. 4

a graphical representation of the actual angle of rotation of the EC motor rotor, wherein the locations where magnetic field sensor pulses occur in the rotation angle curve are marked on the abscissa, the time and on the ordinate of the rotation angle is plotted.

An adjusting device for adjusting the rotational angle or phase angle of the camshaft 11 of a reciprocating internal combustion engine relative to the crankshaft 12 has an adjusting mechanism 13 which is a three-shaft transmission with a crankshaft fixed drive shaft, a camshaft fixed output shaft and one with the rotor of an EC motor 14 in drive connection Adjusting shaft is formed. In Fig. 1 It can be seen that an inductive sensor 15 is provided for measuring the crankshaft rotation angle, which detects the tooth flanks of a gear rim 16 consisting of a magnetically conductive material arranged on the crankshaft 12. One of the tooth gaps or teeth of the toothed rim 16 has a greater width than the other tooth gaps or teeth and serves as a reference mark. The inductive sensor 15 is arranged on a not shown in the drawing engine block of the internal combustion engine.

When passing the reference mark on the sensor 15, the measured value for the crankshaft rotation angle is set to a starting value. Thereafter, the measured value is tracked until the reference mark is passed by the sensor 15 each time a tooth flank is detected. The tracking of the measured value for the crankshaft angle takes place with the aid of a control device in whose operating program an interrupt is triggered in each case when a tooth flank is detected. The crankshaft rotation angle is therefore measured digitally.

As in Fig. 2 can be seen, the EC motor 14 has a rotor 17, on the circumference of a series of magnetized alternately in opposite directions magnetic segments is arranged 1..8, which interact magnetically via an air gap with teeth of a stator, not shown in the drawing , The teeth are wound with a winding, which is energized via a drive device.

The position of the magnet segments 1..8 relative to the stator is detected by means of a measuring device having a plurality of magnetic field sensors A, B, C, which are arranged offset to one another in the circumferential direction of the stator such that per revolution of the rotor a number of Magnetic segment sensor combinations is traversed. If the measurement is error-free, the magnetic field sensors A, B, C generate a digital sensor signal which, due to the arrangement of the magnetic field sensors A, B, C and the passing magnetic segments 1..8, passes through an order of 2 · m sensor signal states m the number the magnetic field sensors A, B, C means. Each sensor signal state has for each magnetic field sensor A, B, C each have a point A ', B', C ', the z. B. "0" or "1" can be. The individual sensor signal states occur in error-free measurement in a predefined order, from which the direction of rotation of the rotor 17 can be seen. This sequence is determined and stored in a non-volatile memory. For three magnetic field sensors A, B, C and positive direction of rotation is the order z. 101, 100, 110. 010, 011, 001.

When the direction of rotation is constant, every sensor signal state is repeated every 2 · m sensor signal values if the measurement is error-free. In one rotor revolution, each pattern occurs p times, where p is the number of pole pairs of the rotor 17. Each change of a sensor signal state triggers an interrupt in the control unit, in which - starting from a start value, the z. B. can be zero - a position measurement signal is tracked. In this case, the position measurement signal z. B. increased by one step and reduced by one step in the negative direction of rotor rotation. If the sensor signal values match the stored order of the sensor signal states, it is assumed that the rotor 17 has rotated by the width of a magnet segment.

On the other hand, if the newly read sensor signal value does not fit into the sequence, it is assumed either that one or more sensor signal states have been lost due to a fault, or that one or more sensor signal states have been received too much. By searching for the sensor signal value in the known order, it is determined how many sensor signal states have been missing or received too much. If, for example, the current sensor signal value was not expected until the next pulse of a magnetic field sensor, then the rotor 17 has been replaced in the meantime z. B. by (2 + m · n) magnetic segment sensor combinations rotated without this being detected. In this case, m is the number of magnetic field sensors of the measuring device and n is an integer number, the z. B. can have the value 0, ± 1, ± 2, etc.

Dividing the position measurement signal value by 2 · m, the integer remainder R is in the range of 0 to 2 · m-1. A sensor signal state is assigned a fixed remainder R. If the association between the sensor signal value and the position measurement signal value is not correct, the sensor signal value is changed by a fine correction so that the assignment is correct again. This is always achievable and can be carried out immediately when reading in a new sensor signal value. In addition to this fine correction, the position measurement signal value can be changed, if necessary, by a coarse correction with whole multiples of 2 × m, since they do not influence the remainder R. The adjusting device has an encoder for the rotational angle position of the camshaft 11, which has a Hall sensor 18 on the engine block, which cooperates with a arranged on the camshaft 11 trigger 19. If the Hall sensor 18 detects an edge of the trigger wheel 19, an interrupt is triggered in the operating program of the control unit, in each case a crankshaft rotational angle measured value and a sensor signal value are buffered. This interrupt will also be referred to as a camshaft interrupt below. At a later time then another interrupt is triggered in the operating program of the controller, in which it is checked whether a coarse correction of the position measurement signal is required and in which this is optionally performed. This interrupt will also be referred to as a cyclic interrupt below.

$${\mathrm{\epsilon }}_2\mathrm{=}\mathrm{\epsilon }\left({\mathrm{t}}_2\right)\mathrm{=}{\mathrm{\varphi }}_{\mathrm{Cnk}\mathrm{,}2}$$

In order to carry out the coarse correction, the gear ratio of the three-shaft transmission and the so-called stationary gear ratio, ie the translation which has the adjusting mechanism 13 when the drive shaft is stationary, are used. At time t _{1 of} a first camshaft interrupt and at time t _{2 of} a second camshaft interrupt, the following applies: $${\mathrm{<figure-callout\; id="1"\; label="\epsilon "\; filenames="imgf0001.png,imgf0002.png"\; state="\{\{state\}\}">\epsilon </figure-callout>}}_{\mathrm{1}}\mathrm{=}\mathrm{<figure-callout\; id="1"\; label="\epsilon \; t"\; filenames="imgf0001.png,imgf0002.png"\; state="\{\{state\}\}">\epsilon \; </figure-callout>}\left({\mathrm{t}}_{}\right)\left({\mathrm{}}_{\mathrm{1}}\right)\mathrm{=}{\mathrm{\phi }}_{\mathrm{cnk}\mathrm{.}\mathrm{1}}$$

$${\mathrm{\epsilon }}_2\mathrm{=}\mathrm{\epsilon }\left({\mathrm{t}}_2\right)\mathrm{=}{\mathrm{\phi }}_{\mathrm{cnk}\mathrm{.}2}$$

In this case, φ _{Cnk denote} the rotational angle of the crankshaft 12, ε the phase angle, the index 1 the time t ₁ and the index 2 the time t ₁ .

For each cyclic interrupt, the following extrapolation equation applies, in which φ _Em (t) the rotor position (rotor rotation angle) at time t, φ _Em , ₁ the rotor position at time t ₁ and φ _Cnk (t) _mean the angle of rotation of crankshaft 12 at time t : $$\epsilon \left(t\right)={\phi }_{\mathit{cnk}.1}+\frac{1}{i_G}\cdot \left(\left[{\phi }_{\mathit{cnk}}\left(t\right)-{\phi }_{\mathit{cnk}.1}\right]-2\left[{\phi }_{\mathit{em}}\left(t\right)-{\phi }_{\mathit{em}.1}\right]\right)$$

If one converts equation (3) according to the rotor position φ _Em , and evaluates it for the time t _{2 of} the next camshaft interrupt, taking into account equations (1) and (2), $${\phi }_{\mathit{em}.2}={\phi }_{\mathit{em}.1}-\frac{i_G-1}{i_G}\cdot \left({\phi }_{\mathit{cnk}.2}-{\phi }_{\mathit{cnk}.1}\right)$$

If an error in the sensor signal is detected between the two camshaft interrupts, the correct rotor angle φ _Em , ₂ can be calculated with this equation and used for the coarse correction of the position measurement value.

For an example, the achievable accuracy should show:

wobei n_Em die Drehzahl des EC-Motors und n_Cam die Drehzahl der Nockenwelle 11 bezeichnen. Folgende Ungenauigkeiten, die als Super- und Subscripts an den einzelnen Winkeln in Grad angegeben sind, seinen vorhanden: $${{\varphi }_{\mathit{Em},2}}_{-7.7}^{+16.2}={{\varphi }_{\mathit{Em},1}}_{-0}^{+8.57}+31.5\cdot \left({{\varphi }_{\mathit{Cnk},2}}_{-0}^{+0.25}-{{\varphi }_{\mathit{Cnk},1}}_{-0}^{+0.25}\right)$$

The EC motor 14 has m = 3 magnetic field sensors and p = 7 pole pairs. The stationary gear ratio of the variable transmission with standing crankshaft 12 is $${\mathrm{i}}_{\mathrm{G}}\mathrm{=}{\mathrm{n}}_{\mathrm{em}}\mathrm{/}{\mathrm{n}}_{\mathrm{Cam}}\mathrm{=}\mathrm{-}\mathrm{62}\mathrm{.}$$

where n _{Em is} the speed of the EC motor and n _{Cam is} the speed of the camshaft 11. The following inaccuracies, which are specified as super and subscripts at the individual angles in degrees, are present: $${{\phi }_{\mathit{em}.2}}_{-7.7}^{+16.2}={{\phi }_{\mathit{em}.1}}_{-0}^{+\mathrm{8:57}}+31.5\cdot \left({{\phi }_{\mathit{cnk}.2}}_{-0}^{+\mathrm{12:25}}-{{\phi }_{\mathit{cnk}.1}}_{-0}^{+\mathrm{12:25}}\right)$$

The uncertainty of the rotor angle of + 16.2 ° / -7.7 ° corresponds to +2 / -1 increments, ie significantly less than 2 · m = 6 increments. A coarse correction using this method is thus possible.

By subtly extrapolating the rotor angle at the first camshaft interrupt, the uncertainty can be halved from + 8.57 ° / - 0 ° to approximately + 2 ° / -2 °. For this purpose, estimated values are determined for the position that the rotor 17 has at the time of the camshaft interrupt and the cyclic interrupt.

Below is the extrapolation based on Fig. 4 explained. At the _instant t _{TrigNW of} the camshaft interrupt, the position _value N _{TrigNW of} the measuring device corresponding to the rotor rotational _{angle value} , the time Δt _TrigNW and the rotational speed ω _{Em, TrigNW} (signed) are available at the last change of the magnetic segment-sensor combination. On appropriate Data can be accessed at each cyclic interrupt. For example, at time t ₁₈ the count N _t18 , the difference time Δt ₁₈ and the speed ω _{Em, t18 are} available.

$${\mathrm{\varphi }}_{\mathrm{Em}\mathrm{,}\mathrm{ti}}\mathrm{=}{\mathrm{N}}_{\mathrm{ti}}\mathrm{\cdot }{\mathrm{\delta }}_{\mathrm{Em}}\mathrm{+}\mathrm{\Delta }{\mathrm{t}}_{\mathrm{i}}\mathrm{\cdot }{\mathrm{\omega }}_{\mathrm{Em}\mathrm{,}\mathrm{ti}}$$

This data can be used to determine the angle swept since the last change of the magnetic segment-sensor combination, and thus the position of the EC motor in the case of the camshaft trigger and the current ECU interrupt t _i, as follows: $${\mathrm{\phi }}_{\mathrm{em}\mathrm{.}\mathrm{TrigNW}}\mathrm{=}{\mathrm{N}}_{\mathrm{TrigNW}}\mathrm{\cdot }{\mathrm{\delta }}_{\mathrm{em}}\mathrm{+}\mathrm{\Delta }{\mathrm{t}}_{\mathrm{TrigNW}}\mathrm{\cdot }{\mathrm{\omega }}_{\mathrm{em}\mathrm{.}\mathrm{TrigNW}}$$

$${\mathrm{\phi }}_{\mathrm{em}\mathrm{.}\mathrm{ti}}\mathrm{=}{\mathrm{N}}_{\mathrm{ti}}\mathrm{\cdot }{\mathrm{\delta }}_{\mathrm{em}}\mathrm{+}\mathrm{\Delta }{\mathrm{t}}_{\mathrm{i}}\mathrm{\cdot }{\mathrm{\omega }}_{\mathrm{em}\mathrm{.}\mathrm{ti}}$$

The resolution δ _{EM of} the measuring device 17 results from the number of pole pairs p and the number m of the magnetic field sensors A, B, C: $${\delta }_{\mathit{em}}=\frac{360°}{2\cdot m\cdot P}=\frac{360°}{2\cdot 3\cdot 7}=\mathrm{8th}.57°.$$

In the method for determining the position of the EC motor 14 for the device for adjusting the rotational angle position of the camshaft 11 of the reciprocating internal combustion engine relative to the crankshaft 12 is thus at each occurrence of a change in state of a sensor signal arranged on the stator of the EC motor 14 magnetic field sensors A, B, C, which are provided for detecting magnetic poles of the EC rotor 17, tracking a position measurement signal. In error-free measurement, the sensor signal undergoes an order of sensor signal states, which occurs at least twice per mechanical revolution of the rotor 17. The order of the sensor signal states is determined and stored. With the aid of the stored sequence, a fine correction of the position measuring signal is carried out if the order of the measured sensor signal values deviates from the stored sequence. In addition, the rotation angle of the crankshaft 12 of the internal combustion engine is determined, and with the aid of the rotation angle and a transmission characteristic of an epicyclic gear of the camshaft adjusting device, a coarse correction of the position measurement signal is performed upon detection of a position measurement error that can not be eliminated with the fine correction.

Bezuaszeichenliste

1..8

Magnetic field sensor

11

camshaft

12

crankshaft

13

variator

14

EC motor

15

sensor

16

sprocket

17

rotor

18

Hall sensor

19

trigger wheel

A

Magnetic field sensor

B

Magnetic field sensor

C

Magnetic field sensor

Claims (6)

1. Position determination method in an EC motor (14) for an apparatus for setting the rotational angle position of the camshaft (11) of a reciprocating piston internal combustion engine relative to the crankshaft (12), the crankshaft (12) having a drive connection to the camshaft (11) via an adjusting gear (13) which is in the form of a triple-shaft gear having a drive shaft fixed to the crankshaft, an output shaft fixed to the camshaft and an adjusting shaft which has a drive connection to the EC motor (14), the rotor (17) of the EC motor (14) having magnetic segments (1..8) which are offset with respect to one another in the circumferential direction and are alternately magnetized in mutually opposite directions, a measuring device being provided for the purpose of determining the position of the rotor (17) relative to the stator of the EC motor (14) and having magnetic field sensors (A, B, C) which are offset with respect to one another in the circumferential direction on the stator, characterized in that these magnetic field sensors (A, B, C) are arranged in such a manner that, in the case of a rotational movement of the rotor (17) in the direction of the arrow (Pf) relative to the stator with error-free measurement, they generate a digital sensor signal which passes through a sequence of sensor signal states which occurs at least twice per mechanical revolution of the rotor (17),

   a) the sequence of sensor signal states being determined and stored,

   b) a position measurement signal being set to a starting value,

   c) the rotor (17) being rotated relative to the stator and the position measurement signal being tracked each time a state change of the sensor signal occurs,

   d) a first rotational angle measured value of the crankshaft (12) being recorded for a first position measured value of the position measurement signal and a second rotational angle measured value of the crankshaft (12) being recorded for a second position measured value,

   e) a control value for the second position measured value being determined with the aid of the first position measured value, the first and second rotational angle measured values and a gear characteristic variable of the adjusting gear,

   f) the difference between the control value and the second position measured value being formed and, if the magnitude of the difference exceeds a predefined limit value, a coarse correction of the position measurement signal being carried out by adding a coarse correction value, which corresponds to the difference, to the second position measured value and adopting the result as the new second position measured value,

   g) a test value for a second sensor signal value associated with the second position measured value being determined using a first sensor signal value associated with the first position measured value and the stored sequence of sensor signal states,

   h) the test value being compared with the second sensor signal value and, if a discrepancy is determined, a fine correction of the position measurement signal being carried out by adding a fine correction value, which corresponds to the distance between the test value in the sequence of sensor signal states and the second sensor signal value, to the second position measured value and adopting the result as the new second position measured value,

   i) and steps c) to h) being run through again if necessary.
2. Method according to Claim 1, characterized in that a crankshaft rotational angle measuring time is respectively recorded for the first and second crankshaft rotational angles, in that the first and second crankshaft rotational angles, the time difference between the crankshaft rotational angle measuring times and the interval of time between the crankshaft rotational angle measuring time for the second crankshaft rotational angle and a reference time are used to extrapolate an estimated value for the rotational angle of the crankshaft (12) at the reference time, and in that the coarse correction and/or the fine correction is/are carried out with this estimated value as the new second rotational angle measured value.
3. Method according to Claim 1 or 2, characterized tin that a position measured value measuring time is respectively recorded for the first and second position measured values, in that the first and second position measured values, the time difference between the position measured value measuring times and the interval of time between the position measured value measuring time for the second position measured value and the reference time are used to extrapolate an estimated value for the value of the position measurement signal at the reference time, and in that the coarse correction is carried out with this estimated value as the new second position measured value.
4. Method according to one of Claims 1 to 3, characterized in that the reference time is generated at a predefined rotational angle position of the camshaft (11).
5. Method according to one of Claims 1 to 4, characterized in that the position measured values are differentiated in order to form angular velocity values.
6. Method according to one of Claims 1 to 5, characterized in that, in order to compensate for tolerances of the magnetic segments (1..8) and/or magnetic field sensors (A, B, C), a correction value is respectively determined and stored for the individual magnetic segment/sensor combinations, and in that the position measured values and/or angular velocity values are corrected using the correction values.

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