DE102009037896A1 - Method for determining geometric errors of actual teeth of 60-2-transmitter wheel arranged on crankshaft of engine, involves comparing calculated tooth pitch with ideal tooth pitch, where errors do not exist with specified correlation - Google Patents

Abstract

The method involves determining middle angular speed based on measured time period for rotation of a transmitter wheel (1) around an angle of 360 degree. Tooth pitch for testing teeth (p27-p30) is calculated according to a specific equation and based on the middle angular speed and measured tooth time, which is shifted around 180 degree to an actual tooth (2). The tooth pitch is compared with ideal tooth pitch (alpha), where geometric errors of the testing teeth do not exist with a specified correlation or the geometric errors of the testing teeth exist with the specified correlation.

Description

Technical area

The The invention relates to a method for determining geometrical errors of actual teeth of a donor wheel. Farther The invention relates to a method for compensating geometrical errors of actual teeth of a donor wheel.

The Encoder wheel is arranged for example on a crankshaft of an engine and rotates with the speed of the engine.

through a determined by means of the encoder wheel speed signal of the crankshaft can calculate the current speed of the engine and a steady Winkeluhr be provided for the crankshaft angle. These both values are used to control the injection and ignition based on.

State of the art

From the DE 42 21 891 C2 is a method for correcting angular errors on a sensor wheel in the determination of the instantaneous speed of a rotating body, in each of which the segment duration of the passage of successive circle segments of the encoder wheel is measured at a sensor and from the circle segments associated speed values are determined known.

The Total time is for one full revolution of the encoder wheel measured at the sensor. The measured total time is determined by the Number of circle segments divided, creating one for each all circle segments the same theoretical segment time duration determined becomes. This theoretical segment duration is in proportion to the current, measured segment duration of a circle segment and thereby time correction factors associated with the circle segments are set determined.

The Time correction factors are fed to an adaptation unit, the speed values assigned to the circle segments with the assigned speed values Corrected time correction factors.

to cylinder-selective determination of the current engine speed Six-cylinder internal combustion engine is the sender wheel on the crankshaft mounted and each a circle segment of 120 ° is one assigned to specific piston cycle.

to Elimination of dynamics errors are at the three circle segments three consecutive measurements each of the total time duration and the three segment durations for determining the time correction factors such that the start for the three measurements consecutively at the beginning of each of the three consecutive Circle segments begins, and that in each of the measurements determined three time correction factors associated with a particular circle segment are each averaged to a cylinder-selective time correction factor and these averaged time correction factors of an adaptation unit be supplied.

The Measurements can be made during a push phase become.

Object of the invention

Of the Invention has for its object to provide a method which is less computationally intensive and an increased resolution has.

Solution of the task

The Task is achieved by a method according to claim 1 solved. Furthermore, the object is achieved by a method solved according to claim 5.

Advantages of the invention

The inventive methods are based on the assumptions that the real engine speed in overrun mode has almost no rotational nonuniformity and drops linearly in certain rotational speed ranges, and that a rotational speed, which is calculated averaged over the entire revolution of 360 °, in the middle the rotation, ie at 180 °, coincides with the real engine speed.

This However, this is only the case if the average rotation is correct is calculated. Because the timekeeping for a full Turn starts at the same actual tooth and stops and the speed in the thrust does not significantly during one revolution, may vary from a tooth or flank distance be assumed by 360 °.

In order to is the average speed over a full one Rotation of 360 ° very accurate, because only the errors the time base can affect the outcome.

If the thus determined average speed assumed as reference speed can, so that the middle tooth (test tooth), d. H. of the offset by 180 ° to the starting tooth tooth, the measured Rotation individually with regard to its tooth pitch checked become.

By a shift of the starting tooth after each measured revolution All actual teeth can be checked one after the other become.

The Speed of the motor correlates with the angular velocity of the motor Phonic wheel. A measurement of time for a complete Turn, d. H. 360 °, the donor wheel, starting for example from a falling edge of a particular tooth to reaching it of this falling edge is individual of potential geometry errors Teeth unaffected. The calculated from the measured time Angular velocity is the mean angular velocity of the Transmitter wheel over the measuring revolution.

Farther it is assumed that the pitches of the individual teeth, d. H. the actual teeth and possibly the missing teeth, the sender wheel are identical.

The ideal tooth pitch α is determined according to the following equation 1: α = 360 ° / total number of teeth (1)

For example For example, a so-called 60-2 encoder wheel 58 includes actual teeth and two missing teeth. The ideal pitch α is here 6 °.

For the methods according to the invention, it is assumed that the mean angular velocity ω coincides with the present by 180 ° angular velocity ω of a tooth (test tooth).

Δt

= gemessene Zeit während einer Umdrehung um den Winkel β von 360° beginnend und endend beim gleichen tatsächlichen Zahn.

The mean angular velocity ω is calculated according to the following equation 2: ω = 360 ° / Δt (2) With

.delta.t

= measured time during one revolution by the angle β starting from 360 ° and ending at the same actual tooth.

mit

t_z

= Zahnzeit (beispielsweise die vergangene Zeit zwischen zwei fallenden Flanken von benachbarten Zähnen).

The local angular velocity ω is determined according to the following equation 3:

With

t _z

Tooth time (for example, the elapsed time between two falling edges of adjacent teeth).

Since it may happen that not all teeth of a donor gear an actual tooth is arranged offset by 180 ° to the test tooth, for example due to the missing teeth of the encoder wheel, the average angular velocity ω be determined according to different variants.

In a first variant, the mean angular velocity ω Beginning and ending with an actual tooth, which connects in the direction of rotation of the sender wheel to a missing tooth, determined.

In a second variant, the average angular velocity is starting and ending with an actual tooth that opposes the Direction of rotation of the encoder wheel connects to a missing tooth, determined.

In a third variant, the mean angular velocity ω due to the missing tooth not used for a complete revolution (360 °), but it is chosen a maximum angular range, which is symmetrical to the test tooth. This largest possible angular range starts with a starting tooth and ends with a final tooth.

Either the starting tooth as well as the end tooth are actual teeth the donor wheel. Both the start tooth and the end tooth are in order each half the largest possible angle range symmetrically offset (once in positive direction of rotation and once in the negative direction of rotation of the encoder wheel) to the test tooth arranged.

For a test tooth, the starting tooth and the end tooth are determined as follows:
If both an addition and a subtraction of half the total number of teeth (including actual teeth and missing teeth) with respect to the test tooth, respectively, an actual tooth is determined, this actual tooth is both the starting tooth and the end tooth for this test tooth.

Otherwise the query takes place, whether with an addition as well as a Subtraction of half the actual number of teeth one actual each with respect to the test tooth Tooth was determined.

Provided this is true, the tooth determined during the subtraction is the starting tooth and the tooth of the end tooth detected during the addition.

Otherwise For each additional query, the previous addend or subtrahend is used decreased by the value "1". The provisions of Starting tooth and the end tooth are analogous.

Provided the result of addition or subtraction is less than "1", the total number of teeth is added to the result. Provided the result is greater than the total number of teeth is subtracted from the result the total number of teeth.

The angle β _se between the starting tooth and the end tooth is calculated according to the following equation 4: β _se = 360 ° - α · (total number of teeth - (2 · value of the addend / subtrahend)). (4)

The direction of the numbering of the teeth coincides with the direction of determination of the angle β _se between the starting tooth and the end tooth.

mit

Δt_se

= gemessene Zeit von Startzahn zu Endzahn während einer Umdrehung um den Winkel β_se.

The mean angular velocity ω _se is calculated according to the following equation 5:

With

Δt _se

= measured time from start tooth to end tooth during one turn around the angle β _se .

t_p

= gemessene Zahnzeit des Prüfzahns.

Since it is assumed that the mean angular velocity ω . ω _se with the offset by 180 ° arranged angular velocity ω of the test tooth, to determine a potential geometric error of the test tooth whose pitch α _p, calculated according to the following equation 6: α _{p, ber} = ω · _P (6) With

t _p

= measured tooth time of the test tooth.

The calculated tooth pitch α _{p, ber} is compared with the ideal tooth pitch α. If there is a match when comparing the calculated tooth pitch α _{p, over} with the ideal pitch α, there is no geometrical error according to the invention.

If one or more missing teeth join the test tooth, the measured tooth time t _p and the calculated tooth pitch α _p, corresponding to this test tooth, are correspondingly longer. To take this into account in the comparison, the ideal tooth pitch α is multiplied by the number of missing teeth directly adjacent to the test tooth.

Around a donor gear completely towards this geometry error check is the comparison for to perform each actual tooth of the sender wheel.

at the implementation of the invention Method for determining geometry errors must be the presence adhered to the overrun phase and a synchronous speed detection become. If either the overrun phase ends or the speed detection Asynchronous, the execution is terminated, and if so Both conditions are met again, the implementation can to be continued.

In the inventive compensation of the geometry error, the current rotational speed n _act in [U / min] of the motor is calculated by the following equation 7, wherein the measured tooth in time t _p [s] is true:

For the compensation of the geometry error in the speed calculation, the currently calculated tooth pitch α _{p, over} the test tooth can be used to reduce the compensation time.

Furthermore, it is possible to supply the already calculated tooth pitches α _p, above the test tooth before the compensation, to a statistical method, for example averaging, in order to increase the robustness with respect to individual measurement errors.

The units indicated in the equations can be determined by means of Factors are converted into other units. For example the unit [s] can be converted by the factor 60 into the unit [min] become.

drawings

It demonstrate:

1 : a schematic representation of a 60-2 encoder wheel;

2 : an angular velocity-time diagram.

In the 1 is a so-called 60-2 donor wheel 1 shown schematically. The donor wheel 1 includes 58 actual teeth 2 and two missing teeth 3 that are shown dotted. The teeth 2 . 3 have an ideal tooth pitch α.

The numbering of the teeth 2 . 3 takes place clockwise (direction of rotation x) starting with the second actual tooth 2 after the missing teeth 3 forming gap. The missing teeth 3 therefore have the number 58 and 59.

For the test tooth p27 with the number 27, the calculation of the associated starting tooth s27 and the end tooth e27 is carried out as follows:
From the number of the test tooth p27 is the half total number of teeth (here: 60, since 58 actual teeth 2 and two missing teeth 3 subtracted and added.
Subtraction: 27 - 30 = -3 + 60 = 57 (number of an actual tooth 2 )
Addition: 27 + 30 = 57 (number of an actual tooth 2 )

The result of the subtraction and addition is each a number of an actual tooth 2 ,

The Number of the starting tooth s27 is the result of the subtraction (here: 57).

The Number of the end tooth e27 is the result of the addition (here: 57).

To calculate the mean angular velocity ω becomes the angle β of 360 ° and measured time duration of the actual tooth 2 with the number 57 up to the actual tooth 2 with the number 57 is used.

For the test tooth p28 with the number 28, the numbers of the starting tooth s28 and the end tooth e28 are calculated as follows:
Subtraction: 28 - 30 = -2 + 60 = 58 (number of missing tooth 3 )
Addition: 28 + 30 = 58 (number of a missing tooth 3 )

Since both results each have a missing tooth number 3 the value of the subtrahend and the addend are decremented by the value "1".
Subtraction: 28 - 29 = -1 + 60 = 59 (number of missing tooth 3 )
Addition: 28 + 29 = 57 (number of an actual tooth 2 )

Because the result of the subtraction is a number of a missing tooth 3 has, the value of the subtrahend and the addend are decremented by the value "1".
Subtraction: 28 - 28 = 0 + 60 = 60 (number of an actual tooth 2 )
Addition: 28 + 28 = 56 (number of an actual tooth 2 )

The result of the subtraction and addition is each a number of an actual tooth 2 ,

The Number of the starting tooth s28 is the result of the subtraction (here: 60).

The Number of the end tooth e28 is the result of the addition (here: 56).

To calculate the mean angular velocity, the angle between the actual tooth 2 with the number 60 and the actual tooth 2 with the number 56, ie 336 ° and the measured time of the actual tooth 2 with the number 60 up to the actual tooth 2 with the number 56, based.

Alternatively, as a start and end tooth of the actual tooth 2 with the number 57 or the actual tooth 2 be dialed with the number 60. The actual tooth 2 with the number 57 closes counter to the direction of rotation x to the missing tooth 3 with the number 58 on. The actual tooth 2 with the number 60 closes in the direction of rotation x to the missing tooth 3 with the number 58 on. In both alternatives, the angle β is 360 °.

For the test tooth p29 with the number 29, the numbers of the starting tooth s29 and the end tooth e29 are calculated as follows:
Subtraction: 29 - 30 = -1 + 60 = 59 (number of missing tooth 3 )
Addition: 29 + 30 = 59 (number of missing tooth 3 )

Since both results each have a missing tooth number 3 the value of the subtrahend and the addend are decremented by the value "1".
Subtraction: 29 - 29 = 0 + 60 = 60 (number of an actual tooth 2 )
Addition: 29 + 29 = 58 (number of missing tooth 3 )

Since the result of the addition is a missing tooth number 3 has, the value of the subtrahend and the addend are decremented by the value "1".
Subtraction: 29 - 28 = 1 (number of an actual tooth 2 )
Addition: 29 + 28 = 57 (number of an actual tooth 2 )

The result of the subtraction and addition is each a number of an actual tooth 2 ,

The Number of the starting tooth s29 is the result of the subtraction (here: 1).

The Number of the end tooth e29 is the result of the addition (here: 57).

The angle β _{29 of} the test tooth p29 is calculated by means of equation 4: β ₂₉ = 360 ° - 6 ° x (60 - 2 x 28) = 336 °.

For the test tooth p30 with the number 30, the calculation of the corresponding starting tooth s30 and of the end tooth e30 as follows:
Subtraction: 30 - 30 = 0 + 60 = 60 (number of an actual tooth 2 )
Addition: 30 + 30 = 60 (number of an actual tooth 2 )

The result of the subtraction and addition is each a number of an actual tooth 2 ,

The Number of the starting tooth s30 is the result of the subtraction (here: 60).

The Number of the end tooth e30 is the result of the addition (here: 60).

In 2 a section of an angular velocity-time diagram for the test teeth p44 to p47 is shown.

The real angular velocity ω drops linearly.

For the test tooth p44 with the number 44, the time Δt ₁₄ is measured for a revolution of 360 ° starting from and ending at the start and end tooth s14, e14 with the number 14. Based on this time period Δt ₁₄ , the average angular velocity ω ₁₄ calculated.

In the diagram, the average angular velocity intersects ω ₁₄ the angular velocity ω after the half time period Δt ₁₄ , ie after 180 °.

At this point of intersection, ie at this time, the angular velocity ω present at test tooth p44 with the number 44 coincides with the calculated mean angular velocity ω ₁₄ match.

Due to this agreement, the tooth pitch becomes α _{44, over} the test tooth p44 with the number 44 based on the mean angular velocity ω ₁₄ and the measured tooth time t ₄₄ calculated according to the equation 6.

After measuring the time period Δt ₁₄ from the start and end teeth s14, e14, the time period Δt ₁₅ from the start and end teeth s15, e15 is measured to calculate the pitch α _{45 over} the test tooth p45 numbered 45.

Analogously, the time periods .DELTA.t ₁₆ , .DELTA.t ₁₇ are detected and the tooth pitches .alpha. _{46, via} , .alpha. 47, are calculated _via the test teeth p46, p47.

By this procedure, after 58 time measurements (for each actual tooth 2 a measurement) the corresponding tooth pitches α _p, and the current speed n _{akt of} the engine are calculated.

LIST OF REFERENCE NUMBERS

1

sensor wheel

2

actual tooth

3

missing tooth

e14

end tooth

e15

end tooth

e16

end tooth

e17

end tooth

e27

end tooth

e28

end tooth

e29

end tooth

e30

end tooth

p27

Prüfzahn

p28

Prüfzahn

p29

Prüfzahn

p30

Prüfzahn

p44

Prüfzahn

p45

Prüfzahn

p46

Prüfzahn

p47

Prüfzahn

s14

start teeth

s15

start teeth

s16

start teeth

s17

start teeth

s27

start teeth

s28

start teeth

s29

start teeth

s30

start teeth

t

Time

x

direction of rotation

α

ideal tooth pitch

β29

angle between start tooth s29 and end tooth e29

Δt14

time

Δt15

time

Δt16

time

Δt17

time

ω

angular velocity

ω14

middle angular velocity

ω15

middle angular velocity

ω16

middle angular velocity

ω17

middle angular velocity

QUOTES INCLUDE IN THE DESCRIPTION

This list The documents listed by the applicant have been automated generated and is solely for better information recorded by the reader. The list is not part of the German Patent or utility model application. The DPMA takes over no liability for any errors or omissions.

Cited patent literature

• - DE 4221891 C2 [0004]

Claims (8)

Method for determining geometrical errors of actual teeth ( 2 ) of a transmitter wheel ( 1 ), where a mean angular velocity ( ω ) based on a measured time duration (Δt, Δt ₁₄ , Δt ₁₅ , Δt ₁₆ , Δt ₁₇ ) for one revolution of the encoder wheel ( 1 ) starting at an angle (β) of 360 ° and ending at an actual tooth ( 2 ) is determined according to the following equation: ω = β / Δt, and the mean angular velocity ( ω ) And a measured tooth period (t _p) of a Prüfzahns (p, p27, p28, p29, p30, p44, p45, p46, p47) of the offset by 180 ° (at this actual tooth 2 ), a tooth pitch (α _{p, ber} ) for this test tooth (p, p27, p28, p29, p30, p44, p45, p46, p47) is calculated according to the following equation: α _{p, ber} = ω · _P , and the calculated tooth pitch (α _{p, ber} ) is compared with an ideal tooth pitch (α), and where there is no geometrical error of the test tooth (p, p27, p28, p29, p30, p44, p45, p46, p47), and otherwise a geometric error of the test tooth (p, p27, p28, p29, p30, p44, p45, p46, p47) is present. Method according to claim 1, characterized in that the tooth pitch (α _{p, ber} ) of a test tooth (p, p27, p28, p29, p30, p44, p45, p46, p47) offset by 180 ° to a missing tooth ( 3 ) of the encoder wheel ( 1 ) is arranged, based on a mean angular velocity ( ω ), the mean angular velocity ( ω ) starting and ending with an actual tooth ( 2 ) in or against a direction of rotation (x) of the encoder wheel ( 1 ) to this missing tooth ( 3 ), is determined. Method according to claim 1, characterized in that the tooth pitch (α _{p, ber} ) of a test tooth (p, p27, p28, p29, p30, p44, p45, p46, p47) offset by 180 ° to a missing tooth ( 3 ) of the encoder wheel ( 1 ) is arranged, based on a mean angular velocity ( ω _se ) between a start tooth (s, s14, s15, s16, s17, s27, s28, s29, s30) and an end tooth (e, e14, e15, e16, e17, e27, e28, e29, e30) is determined according to the following equation: α _{p, ber} = ω _se · t _p , where the mean angular velocity ( ω _se ) calculated according to the following equation:

with β _se = angle between the starting tooth (s, s14, s15, s16, s17, s27, s28, s29, s30) and the end tooth (e, e14, e15, e16, e17, e27, e28, e29, e30) Δt _se = measured time during one revolution by the angle β _se . Method according to claim 3, characterized in that the angle (β _se ) between the starting tooth (s, s14, s15, s16, s17, s27, s28, s29, s30) and the end tooth (e, e14, e15, e16, e17 , e27, e28, e29, e30) is determined according to the following equation: β _se = 360 ° - α · (total number of teeth - (2 · value of the addend / subtrahend)), where the total number of teeth is the number of actual teeth ( 2 ) and possibly the missing teeth ( 3 ) of the encoder wheel ( 1 ) and where the value of the addend / subtrahend is the number of teeth ( 2 . 3 ) between the test tooth (p, p27, p28, p29, p30, p44, p45, p46, p47) and the end tooth (e, e14, e15, e16, e17, e27, e28, e29, e30) or the starting tooth (s , s14, s15, s16, s17, s27, s28, s29, s30). Method according to at least one of the preceding claims, characterized in that in one or more missing teeth (p, p27, p28, p29, p30, p44, p45, p46, p47) directly adjoining the test tooth ( 3 ) the ideal tooth pitch (α) with the number of directly adjacent missing teeth ( 3 ) is multiplied. Method for compensating geometrical errors of actual teeth ( 2 ) of a transmitter wheel ( 1 ) in calculating the speed of a motor, wherein a geometry error of an actual tooth ( 2 ) is determined according to at least one of claims 1 to 5, and wherein a current speed n _{akt of} the engine by means of the calculated tooth pitch (α _{p, ber} ) is calculated according to the following equation:

A method according to claim 4, characterized in that for the calculation of the current speed n _act a currently calculated tooth pitch (α _{p, over} ) is used. A method according to claim 4, characterized in that for calculating the current speed n _act calculated tooth pitch (α _{p, ber} ) is based, using a statistical method of at least two previously calculated tooth pitches (α _{p, over} ) of this test tooth (p, p27, p28, p29, p30, p44, p45, p46, p47).

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