DE112011103807B4 - Method for determining the crosstalk behavior of a double clutch system - Google Patents

Abstract

Method for determining the crosstalk behavior of a dual clutch system in a dual clutch transmission in the drive train of a motor vehicle with a drive unit, wherein the dual clutch transmission comprises two subtransmissions, each subtransmission being assigned a friction clutch of the dual clutch system, which is arranged between each subtransmission and the drive unit, in which one In the first, one gear is pre-selected in the active sub-transmission and neutral is pre-selected in the other, the inactive sub-transmission, both clutches of the sub-transmission are fully open, the drive unit runs at idle speed, the vehicle is held at a standstill by a vehicle brake, with the following steps being carried out one after the other a) the clutch of the inactive sub-transmission is moved to an initial position along the travel path of the clutch in which the clutch is at least partially open b) the clutch of the active sub-transmission s is driven several times, starting from the fully open position up to a predetermined torque, which is a predetermined value greater than a predetermined touch point torque, in the closing direction, the position of the clutch of the active sub-transmission at which the torque of the drive unit is equal to is the predetermined touch point moment, is evaluated as touch point position c) the mean value over the determined touch point positions, which were determined due to the repeated driving of the clutch of the active sub-transmission in the closing direction in step b), is formed d) the clutch of the inactive sub-transmission is a predetermined distance in Moved towards closing and the method is continued in step b) until the clutch of the inactive sub-transmission has reached an end position in which the clutch is at least partially closed, characterized in that if in step b) starting from the fully open position up to e In a given moment, which is a given value greater than a given touch point moment, is driven in the closing direction, filtering of a clutch position signal and the torque signal of the drive unit is carried out with a filter with the same properties.

Description

The invention relates to a method having the features according to the preamble of claim 1.

In double clutch systems, the frictional connection between the combustion engine and the wheel is implemented through two parallel paths, each consisting of a clutch and a sub-transmission. The paths are merged in the direction of the wheel via the differential. An example of a known dual clutch system is shown in 1 shown.

• - Überschneidungen während des Wechsels des Kraftflusses von einem Teilgetriebe auf das andere und bei der
• - Tastpunktermittlung über Auswertung der Getriebeeingangsdrehzahlen.

The crosstalk behavior has an influence on

• - Overlaps during the change of the power flow from one part of the transmission to the other and during the
• - Detection of tactile points by evaluating the transmission input speeds.

Influence of the crosstalk behavior in the event of overlaps during the change of the power flow from one sub-transmission to the other:

In the various driving situations, one clutch is predominantly engaged, with a gear being engaged on the associated partial transmission. If you change the frictional connection from one sub-transmission to the other, e.g. 1st gear is engaged in sub-transmission 1 and driven with the clutch engaged and 2nd gear is preselected in sub-transmission 2, clutch 1 is opened in a ramp-shaped manner and clutch 2 is switched to sub-transmission 2 is closed in a ramp.

With this so-called overlap, the sum of both clutch torques ideally results in the applied engine torque. Even small deviations in a clutch model compared to the real system can lead to excessive torque or torque holes, which can seriously disrupt driving comfort due to a jolting perceived by the driver.

DE 103 47 114 A1 discloses a method for determining the crosstalk behavior of a dual clutch transmission.

DE 10 2007 050 987 A1 discloses a drive train arrangement of a motor vehicle having at least one internal combustion engine and an electric machine that can be coupled thereto by means of a clutch, at least one clutch touch point being able to be determined on the basis of a change in the speed of the electric machine.

DE 196 52 244 A1 discloses a method for determining a gripping point of a coupling system in a motor vehicle.

Investigations have shown that the crosstalk behavior of the clutches has a non-negligible influence, since the touch point of the other clutch and thus the clutch model changes significantly. At the beginning of an overlapping shift, one clutch is closed very far while the other clutch is just closed. According to current knowledge, the clutch to be closed always transmits more torque than expected; in total, this would lead to an excessive torque. When the clutch is fully closed, for example, a not inconsiderable shift of the touch point of 1-2 mm on the other clutch must be expected.

• Die spezielle Anordnung mit zwei parallelen Pfaden in einem Doppelkupplungsgetriebe erlaubt die Bestimmung der Tastpunkte über die Auswertung der Getriebeeingangsdrehzahlen. Derartiges ist beispielsweise in der DE 10 2010 024 941 A1 offenbart. Hierzu fährt man beispielsweise auf einem Teilgetriebe, während auf dem anderen Teilgetriebe der Gang ausgelegt und die Kupplung geöffnet ist. Durch Beobachtung des Drehzahlverlaufes der Getriebeeingangswelle, in einer ersten Phase, wird auf ein Schleppmoment geschlossen. Später in einer zweiten Phase, beim Schließen der Kupplung auf ein kleines Moment, wird auf ein Kupplungsmoment geschlossen. Durch Vergleich des angeforderten und des tatsächlich erreichten Kupplungsmomentes kann der Tastpunkt und damit das Modell auf der inaktiven Kupplung während der Fahrt ermittelt und damit adaptiert werden.

Influence of the crosstalk behavior when determining the touch point by evaluating the transmission speeds:

• The special arrangement with two parallel paths in a dual clutch transmission allows the detection points to be determined by evaluating the transmission input speeds. Such is for example in the DE 10 2010 024 941 A1 disclosed. For this purpose, one drives, for example, on a partial transmission, while the gear is disengaged and the clutch is disengaged on the other partial transmission. By observing the speed curve of the transmission input shaft, in a first phase, a drag torque is deduced. Later in a second phase, when the clutch is closed for a small torque, a clutch torque is concluded. By comparing the required clutch torque and the clutch torque actually achieved, the touch point and thus the model on the inactive clutch can be determined while driving and thus adapted.

If the crosstalk behavior of the clutches is not taken into account when determining the touch point by evaluating the transmission input speeds at the current construction status, then the touch point cannot be determined with sufficient accuracy.

Crosstalk model:

zu bestimmen.It has become known to compensate for the crosstalk behavior, for example, as follows. The following dependency of the current clutch position x̃ is used to generate a torque via the clutch characteristic curve f $$\mathrm{M.}=f\left(\tilde{x}\right)$$

to determine.

The result depends on the index of the coupling $$\begin{array}{l}{\tilde{x}}_1=x_1+a_1{x}_2+b_1{x}_2^2\\ {\tilde{x}}_2=x_2+a_2{x}_1+b_2{x}_1^2.\end{array}$$

For the two clutches, the parameters a _i and b _i must therefore be determined with i ∈ {1; 2}.

Determination of the model parameters on a commissioning test bench:

It has already been proposed to determine the parameters a _i and b _{i of} the crosstalk model for each clutch at the end of the line on a transmission commissioning test bench and to ^{store them in the E 2} Prom memory of the control unit for further use.

For example, the routine closes the active clutch on the transmission test bench to a low torque at which a clutch torque that is as stable as possible is transmitted. The test stand sets a previously defined slip between the drive and output side of the clutch, which is stabilized by a control. A gear is engaged in the active sub-transmission, while neutral is preselected in the inactive sub-transmission. The routine closes the inactive clutch on this sub-transmission with a position ramp and then opens it again. The torque that is transmitted via the active clutch changes when the inactive clutch is actuated.

The parameters for the crosstalk model for each clutch can then be determined from the course of the measured torque.

The determination of the model parameters on the commissioning test bench is used to learn the parameters before the first operation. This determination can only be carried out once on the transmission test bench after the clutch has been installed in the transmission bell housing. It is not possible to determine the parameters again later without a gearbox test bench.

If only the double clutch system without the gearbox is exchanged in the workshop for servicing, the crosstalk behavior must also be determined for this clutch system.

In certain cases, the polynomial representation of crosstalk is unsuitable for implementation in the control unit. The representation as a characteristic curve or map allows more complex forms.

The present invention is based on the object of proposing a method which allows the determination of parameters for a crosstalk model for both clutches of the double clutch, for example using the clutch control software in the vehicle without the aid of a transmission test bench.

The object is achieved by a method having the features according to claim 1.

1. a) die Kupplung des inaktiven Teilgetriebes wird in eine Anfangsposition entlang des Verfahrwegs der Kupplung gefahren, in der die Kupplung zumindest teilweise geöffnet ist
2. b) die Kupplung des aktiven Teilgetriebes wird mehrmals ausgehend von der vollständig geöffneten Position bis zu einem vorgegebenen das um einen vorgegebenen Wert größer ist als ein vorgegebenes Tastpunktmoment, in Richtung Schließen gefahren, wobei jeweils die Position der Kupplung des aktiven Teilgetriebes, an der das Drehmoment der Antriebseinheit gleich dem vorgegebenen Tastpunktmoment ist, als Tastpunktposition gewertet wird
3. c) der Mittelwert über die ermittelten Tastpunktpositionen, die aufgrund des mehrmaligen Fahrens der Kupplung des aktiven Teilgetriebes in Richtung Schließen in Schritt b) ermittelt wurden, wird gebildet
4. d) die Kupplung des inaktiven Teilgetriebes wird um eine vorgegebene Strecke in Richtung Schließen gefahren und das Verfahren wird in Schritt b) fortgesetzt bis die Kupplung des inaktiven Teilgetriebes eine Endposition erreicht hat, in der die Kupplung zumindest teilweise geschlossen ist.

According to the invention, a method is proposed for determining the crosstalk behavior of a dual clutch system in a dual clutch transmission in the drive train of a motor vehicle with a drive unit, the dual clutch transmission comprising two sub-transmissions, each sub-transmission being assigned a friction clutch of the double clutch system, which is arranged between a sub-transmission and the drive unit . According to the invention, one gear is preselected in a first, the active sub-transmission and neutral is preselected in the other, the inactive sub-transmission, both clutches of the sub-transmissions are fully open, the drive unit runs at idle speed, the vehicle is at a standstill by a vehicle brake while the following steps are carried out in sequence:

1. a) the clutch of the inactive sub-transmission is moved into an initial position along the travel path of the clutch, in which the clutch is at least partially open
2. b) the clutch of the active part of the transmission is several times starting from the complete Open position up to a predetermined value which is greater than a predetermined touch point torque by a predetermined value, driven in the direction of closing, the position of the clutch of the active sub-transmission, at which the torque of the drive unit is equal to the predetermined touch point torque, being evaluated as the touch point position
3. c) the mean value over the determined touch point positions, which were determined due to the multiple driving of the clutch of the active sub-transmission in the closing direction in step b), is formed
4. d) the clutch of the inactive sub-transmission is moved a predetermined distance in the direction of closing and the process is continued in step b) until the clutch of the inactive sub-transmission has reached an end position in which the clutch is at least partially closed.

According to the invention, it is provided that if, in step b), starting from the fully open position up to a predetermined torque, which is a predetermined value greater than a predetermined touch point torque, in the closing direction, filtering of a clutch position signal and the torque signal of the drive unit is carried out with a filter with the same properties.

In a preferred embodiment of the invention it is provided that in step a) the starting position of the clutch of the inactive sub-transmission is the fully open position.

In a further preferred embodiment of the invention, it is provided that in step b) the clutch of the active sub-transmission is driven several times in the form of a ramp in the direction of closing.

In a further preferred embodiment of the invention it is provided that in step b) the clutch of the active sub-transmission is driven three times in the direction of closing.

In a further preferred embodiment of the invention it is provided that in step b) the specified value by which the specified torque is greater than the specified touch point torque is 0.1 to 75 percent of the specified touch point torque.

In a further preferred embodiment of the invention it is provided that in step b) the specified torque is a specified torque of the drive unit.

In a further preferred embodiment of the invention, it is provided that the predetermined distance of the clutch of the inactive sub-transmission in step d) has the same value for each passage of step d).

In a further preferred embodiment of the invention it is provided that in step d) the end position of the clutch of the inactive sub-transmission is the completely closed position.

In a further preferred embodiment of the invention, it is provided that, when the inactive clutch is completely disengaged, a touch point position of the active clutch is determined in step b) which deviates too far from a touch point position previously determined by another method for determining the touch point position, in particular a touch point start-up , the tactile point position determined in step b) is not taken into account in the averaging of step c) or taken less into account by weighting.

With the method according to the invention, the crosstalk behavior is thus determined for the clutch that has been designated as active up to now. The crosstalk behavior is the mean value of the determined touch point positions against the clutch position of the inactive clutch. The method must now also be carried out for the clutch, which has been designated as inactive up to now.

With the method according to the invention, the repeated implementation of the determination of the crosstalk behavior - that is, the determination of the parameters for the crosstalk model - can also be carried out during each visit to the workshop without the use of a transmission test bench being necessary.

Further advantages and advantageous embodiments of the invention are the subject of the following description and the following figures.

• 1: ein Blockschaltbild eines in seinem Aufbau an sich bekannten Doppelkupplungsgetriebes mit zugehöriger elektronischer Steuereinrichtung
• 2: Positionsrampen auf der aktiven Kupplung beeinflussen das Motormoment und die Motordrehzahl
• 3: Beispielhaft ermittelte Kennlinien für das Übersprechen
• 4: Darstellung Moment über Position
• 5: schematische Darstellung des erfindungsgemäßen Verfahrensverlaufs

They show in detail:

• 1 : a block diagram of a double clutch transmission known per se in its structure with associated electronic control device
• 2 : Position ramps on the active clutch influence the engine torque and the engine speed
• 3 : Characteristic curves determined by way of example for crosstalk
• 4th : Representation of moment over position
• 5 : schematic representation of the process according to the invention

The solution to the above-mentioned task is to determine the parameters for the crosstalk model in the vehicle by means of a routine developed for this purpose and to use them for later compensation of the path requirements during operation.

5 shows schematically the course of the method according to the invention for solving the problem. The vehicle is in process step 510 Prepared for the determination of the crosstalk behavior by preselecting a gear in a first, the active sub-transmission and preselecting neutral in the other, the inactive sub-transmission. Both clutches of the sub-transmissions are fully opened, the drive unit runs at idle speed, the vehicle is held at a standstill by a vehicle brake. Then we in process step 510 the clutch of the inactive sub-transmission is still moved into an initial position along the travel path of the clutch in which the clutch is at least partially open.

In process step 520 the clutch of the active part of the transmission is driven several times starting from the fully open position up to a specified torque that is a specified value greater than the specified touch point moment in the direction of closing, the position of the clutch of the active part of the transmission being the same as the torque of the drive unit is the specified touch point moment is evaluated as touch point position.

In process step 530 the mean value over the determined touch point positions due to the multiple driving of the clutch of the active sub-transmission in the direction of closing in process step 520 was determined.

In process step 540 the clutch of the inactive sub-transmission is moved a specified distance in the direction of closing.

In process step 550 we checked whether the clutch of the inactive partial transmission has reached an end position. If this is the case, the process is carried out in process step 560 completed. If this is not the case, step 520 continued.

The procedure is described in more detail below.

The vehicle is prepared for the determination of the crosstalk behavior by preselecting a gear in the active sub-transmission and neutral in the inactive sub-transmission. The drive motor, usually an internal combustion engine, is ready for operation and runs at idle speed. Both clutches are fully open. The vehicle's brakes are applied. This takes place in process step 510 .

A fixed position is approached on the inactive clutch - what is in process step 510 takes place - that in each cycle - what the course of process step 520 to process step 550 - is increased to the next value, which is in process step 540 he follows. Several positions are specified in the entire travel path of the clutch actuator belonging to the inactive clutch. A uniform division of the total path into equidistant sections between the fully open and the fully closed position proves to be advantageous - which is the case in process step 550 is checked - including these two positions themselves.

The active clutch is now several times - in the process step 520 - Closed ramp-shaped per cycle except for a small moment above the touch point moment. In 2 a cycle is given as an example in which the inactive clutch 120 is fixed at 35mm, while there are three position ramps on the active clutch 110 to be driven just above the tactile point.

If the engine torque signal delivered by the vehicle exceeds the firmly defined touch point torque, the current clutch position is interpreted as the position for the touch point, which is shown in step 520 is provided. A touch point position can be determined for each individual ramp in the cycle. At the end of the cycle, averaging is then made over all the determined touch point positions, which is shown in step 530 he follows. In this way, exactly one mean touch point position is obtained for one cycle. Measurements show that the averaged touch point position shifts to smaller values the further the inactive clutch is closed.

If the deviations between the averaged touch point positions when the inactive clutch is not fully open and the averaged touch point position when the inactive clutch is fully open over the associated position of the inactive clutch, a characteristic curve is obtained which reflects the crosstalk behavior. The absolute touch point positions are adjusted by the touch point position when the inactive clutch is open. In 3 are an example of the characteristic curves determined for the crosstalk of both clutches 210 , 220 of the double clutch system.

The method described above must therefore be carried out separately for both the one and the other clutch of the double clutch system.

Closing the active clutch:

• e) Die aktive Kupplung wird über eine Positionsrampe bis knapp über die aktuell in der Software hinterlegte Tastpunktposition geschlossen. Da die Tastpunktposition in jedem Zyklus unterschiedlich sein wird, besteht die Gefahr, dass der Antriebsmotor, speziell bei einer Verbrennungskraftmaschine, abwürgt.
• f) Die aktive Kupplung wird über eine Positionsrampe so lange geschlossen bis der Motor ein Moment größer als das geforderte Tastpunktmoment anzeigt. Da das Motormomentensignal im Fahrzeug starken Rausch-/Störeinflüssen (z.B. durch Zuschalten elektrischer Verbraucher) unterliegen kann, kann es vorkommen dass die geforderte Momentenschwelle viel früher im vom Motor angezeigten Signal erreicht wird und so fälschlicherweise eine zu kleine Tastpunktposition für diese Rampe ermittelt wird.
• g) Die aktive Kupplung wird über eine Positionsrampe so lange geschlossen bis die Motordrehzahl deutlich unter die Leerlaufdrehzahl sinkt. In 2 ist der Verlauf der Motordrehzahl beispielhaft dargestellt.

There are several options for closing the active clutch except for a moment that is above the touch point moment:

• e) The active clutch is closed via a position ramp to just above the touch point position currently stored in the software. Since the touch point position will be different in each cycle, there is a risk that the drive motor, especially in an internal combustion engine, stalls.
• f) The active clutch is closed via a position ramp until the motor displays a torque greater than the required touch point torque. Since the engine torque signal in the vehicle can be subject to strong noise / interference influences (e.g. due to the connection of electrical consumers), it can happen that the required torque threshold is reached much earlier in the signal displayed by the engine and that a touch point position that is too small for this ramp is incorrectly determined.
• g) The active clutch is closed via a position ramp until the engine speed falls well below the idle speed. In 2 the course of the engine speed is shown as an example.

It is conceivable to combine conditions e), f) and g) using a suitable logic.

Filtering the signals:

When determining the touch point during a ramp of a cycle, if the position signal and the motor torque signal are filtered with a filter with the same properties, the signal curve for the evaluation of reaching the required torque threshold, which - as described above - is a small torque above the touch point torque, can be smoothed become.

Not only the measured engine torque but also the clutch position is filtered and then these two signals are used for the evaluation. Both signals, the measured engine torque and the measured clutch position, are filtered with a filter with the same properties, i.e. the same parameters.

By filtering the signals with a filter that has the same properties, the clutch position signal is delayed in the same way as the torque signal. This eliminates the previously prevailing delay of the filtered torque signal compared to the unfiltered, measured clutch position signal.

If the position signal and the torque signal are filtered with a filter with the same properties, the same phase shift results on both signals, so that the characteristic curve is displayed 330 , Moment over position the phase shift no longer has any influence on how out 4th can be seen.

Any torque threshold:

Alternatively, the clutch can be closed to any other torque threshold instead of just above the touch point torque, but it should be noted that the smaller the torque threshold, the stronger the effects of noise / interference from the motor torque. The higher the torque threshold is assumed, the easier it is for the engine to stall if an internal combustion engine is used as the drive machine.

Plausibility check of the determined touch point positions:

• Bei geöffneter inaktiver Kupplung wird ein Tastpunkt der aktiven Kupplung nahe dem zuvor durch die Tastpunktinbetriebnahme ermittelten Tastpunkt erwartet. Weicht der Tastpunkt, der durch die Rampe ermittelt wird, zu stark ab, kann z.B. verzichtet werden diese spezielle Messung in der Mittelwertbildung zu berücksichtigen oder durch eine geeignet gewählte Gewichtung schwächer zu berücksichtigen.
  • - Da die inaktive Kupplung in jedem Zyklus immer nur ein Stück weiter als im letzten Zyklus geschlossen wird, ist zu erwarten, dass sich neu ermittelte Tastpunkt-/Momentenschwellenpositionen innerhalb eines Bandes um die zuletzt ermittelte Tastpunkt-/Momentenschwellenposition des letzten Zyklus befindet.
  • - Aus Messungen ist bekannt, dass sich die Tastpunkt-/Momentenschwellenposition für eine weit geschlossene inaktive Kupplung monoton ändert. Es kann somit in diesem Bereich auf Monotonität geprüft werden.

The averaging of the determined touch point positions or positions that belong to the selected torque threshold can be expanded by a plausibility check:

• When the inactive clutch is open, a touch point of the active clutch close to the touch point previously determined by the touch point start-up is expected. If the touch point that is determined by the ramp deviates too much, it is possible, for example, to dispense with taking this special measurement into account in the mean value formation or taking it into account to a lesser extent through a suitably selected weighting.
  • - Since the inactive clutch is only closed a little further in each cycle than in the last cycle, it is to be expected that the newly determined touch point / torque threshold positions are within a band around the last determined touch point / torque threshold position of the last cycle.
  • - It is known from measurements that the touch point / torque threshold position changes monotonically for a widely closed inactive clutch. It can thus be checked for monotony in this area.

Plausibility check of the engine torque:

If the active clutch is fully open, the engine torque signal delivered by the engine should be constant. Larger changes suggest that the signal is subject to interference. In this case, the start of the ramp could be delayed until the motor torque signal has stabilized again or the process could be canceled.

No need to commission the touch point:

Alternatively, the touch point commissioning can be dispensed with in service for reasons of time and the touch point position can be derived from the determination of the touch point / torque threshold position for a completely opened inactive clutch from the determination of the parameters for the crosstalk model presented here.

Use of the engine speed information:

Alternatively, instead of an engine torque threshold at which an associated clutch position is determined, the speed below an engine speed threshold can be used. The prerequisite, however, is that the engine management system does not adapt itself too much and that a similar behavior is reproducible.

Repeated determination of parameters during service or inspection:

The repeated implementation of the parameter determination for the crosstalk model can also be carried out during each workshop visit.

In order to avoid detrimental influences on the torque accuracy during the change of the power transmission from one partial clutch to the other, and to be able to provide a torque at all during the touch point adaptation via the evaluation of the transmission input speeds that allows the touch point adaptation, precise parameters for the crosstalk behavior are necessary To determine clutch.

It has already been proposed to determine the parameters for a crosstalk model on the commissioning test bench; there is currently no way to determine the parameters for a crosstalk model for the replacement of clutches in the workshop during service. The method presented here allows the parameters for a crosstalk model to be determined directly in the vehicle by executing a diagnostic command. This also opens up the possibility of relearning the parameters of the crosstalk model with each inspection and thus adapting it to clutch wear.

According to 1 a per se known double clutch or parallel shift transmission has a drive shaft driven, for example, by an internal combustion engine 6th on, optionally with two input shafts 8th and 10 is rotatably connectable. The flow of torque from the drive shaft 6th into the input shafts 8th and 10 is via one coupling each K1 and K2 optionally controllable. Between the input shaft 8th and an output shaft 12 different gear ratios can be switched via wheel pairs, only one of which is shown. Likewise are between the input shaft 10 and the output shaft 12 different wheel pairs switchable, of which only one is shown. To operate the clutches K1 and K2 are actuators 14th and 16 intended. To switch the wheel pairings, for example to establish a non-rotatable connection between the one on the input shaft 8th or 10 arranged wheel with the respective input shaft 8th or 10 , that with a respective one, with the output shaft 12 Actuators are actuators 18th and 20th provided, each of which can contain a switching actuator and a selector actuator, for example. Overall form the input shaft 8th and the output shaft 12 as well as the input shaft 10 and the output shaft 12 a partial transmission each 22nd or. 24 of the double clutch transmission.

To control the actuators 14th , 16 , 18th and 20th an electronic control device is used 26th with microprocessor and associated program and data memories, the outputs of which control one of the actuators and their inputs 28 with sensors 30th , 32 or. 34 connected to the speed of the drive shaft 6th , the input shaft 8th and the input shaft 10 detect, as well as other sensors for detecting operating parameters of the vehicle drive train, for example a sensor for detecting the speed of the driven vehicle wheels, a sensor for detecting the position of a gear selector lever, a sensor for detecting the position of an accelerator pedal, etc. The control device shown 26th can be connected to other control units of the vehicle via a bus system, for example an engine control unit with which a power actuator of the engine is controlled. The actuators can be designed as lever actuators, for example, which are controlled by an electric motor, for example, the rotation of each electric motor being recorded by an incremental counter (not shown).

The torque that can be transmitted by the clutch is important for the function of a clutch and is stored in a memory of the control device 26th stored as a curve which indicates the transferable clutch torque depending on the position of a clutch actuator, for example a clutch lever. In the event of a change in the functional state of the clutch due to wear and the like, the characteristic curve must be updated, which is done using adaptation methods, for which purpose, for example, the touch point of the clutch must be checked during driving and adapted to any changes in the clutch properties that may arise.

1 shows a block diagram of a double clutch transmission known per se in terms of its structure with an associated electronic control device. The in 1 shown dual clutch transmission can in the respective sub-transmission 22nd or 24 whose clutch is open, a gear can be engaged, while the effective translation of the transmission is determined by that sub-transmission whose clutch is closed. If in the partial transmission 22nd For example, a gear is engaged and the clutch K1 is closed, then this gear is for the translation between the drive shaft 6th and the output shaft 12 effective. At the same time can in the other partial transmission 24 a new gear to be shifted must be engaged. When shifting the transmission from the currently engaged gear to the newly engaged gear, the clutch must K1 opened and, for a traction-free connection between the drive shaft 6th and the output shaft 12 , the coupling K2 overlapping closed. When the clutch K2 the torque transmission takes over, if not at least one of the clutches K1 , K2 at the same time slips, the gear is destroyed by overdetermining the ratios Therefore, at least intermittently, when both clutches K1 , K2 are simultaneously closed beyond their touch point, the touch point being defined as the point from which the clutch transmits torque with increasing engagement (at the touch point a torque of at most a few Newton meters is transmitted), a slipping state is established in which at least one of the two clutches K1 , K2 slips.

List of reference symbols

6th

drive shaft

8th

Input shaft

10

Input shaft

12

Output shaft

14th

Actuator

16

Actuator

18th

Actuator

20th

Actuator

22nd

Partial transmission

24

Partial transmission

26th

Control device

28

Entrances

30th

sensor

32

sensor

34

sensor

K1

coupling

K2

coupling

110

active clutch

120

inactive clutch

210

Clutch 1

220

Clutch 2

310

measured moment over measured position

320

filtered moment over measured position

330

filtered moment over filtered position

510

Process step

520

Process step

530

Process step

540

Process step

550

Process step

560

Process step

Claims (9)

Method for determining the crosstalk behavior of a dual clutch system in a dual clutch transmission in the drive train of a motor vehicle with a drive unit, the dual clutch transmission comprising two subtransmissions, each subtransmission being assigned a friction clutch of the dual clutch system, which is arranged between each subtransmission and the drive unit, in which one First, the active sub-transmission a gear is preselected and in the other, the inactive sub-transmission neutral is preselected, both clutches of the sub-transmission are fully open, the drive unit runs at idle speed, the vehicle is held at a standstill by a vehicle brake, with the following steps being carried out one after the other a) the clutch of the inactive sub-gear is moved into an initial position along the travel path of the clutch in which the clutch is at least partially open b) the clutch of the active sub-gear bes is driven several times, starting from the fully open position up to a predetermined torque, which is a predetermined value greater than a predetermined touch point torque, in the closing direction, with the position of the clutch of the active sub-transmission at which the torque of the drive unit is equal to the given touch point moment, is evaluated as touch point position c) the mean value over the determined touch point positions, which were determined due to the multiple driving of the clutch of the active sub-transmission in the closing direction in step b), is formed d) the clutch of the inactive sub-transmission is set by a specified Distance driven in the direction of closing and the method is continued in step b) until the clutch of the inactive sub-transmission has reached an end position in which the clutch is at least partially closed, characterized in that if in step b) starting from the fully open position to at a predetermined moment, which is greater by a predetermined value than a predetermined touch point moment, is driven in the closing direction, filtering of a clutch position signal and the torque signal of the drive unit is carried out with a filter with the same properties. Procedure according to Claim 1 , characterized in that in step a) the starting position of the clutch of the inactive sub-transmission is the fully open position. Procedure according to Claim 1 or 2 , characterized in that in step b) the clutch of the active sub-transmission is driven several times in a ramp-shaped manner in the direction of closing. Method according to one of the preceding Claims 1 to 3 , characterized in that in step b) the clutch of the active sub-transmission is moved three times in the direction of closing. Method according to one of the preceding Claims 1 to 4th , characterized in that in step b) the specified value by which the specified torque is greater than the specified touch point torque is 0.1 to 75 percent of the specified touch point torque. Method according to one of the preceding Claims 1 to 5 , characterized in that in step b) the predetermined torque is a predetermined torque of the drive unit. Method according to one of the preceding Claims 1 to 6th , characterized in that the predetermined distance of the clutch of the inactive sub-transmission in step d) has the same value for each pass of step d). Method according to one of the preceding Claims 1 to 7th , characterized in that in step d) the end position of the clutch of the inactive sub-transmission is the fully closed position. Method according to one of the preceding Claims 1 to 8th , characterized in that if a touch point position of the active clutch is determined in step b) when the inactive clutch is completely disengaged which deviates too far from a touch point position previously determined by another method for determining the touch point position, in particular a touch point start-up, the to take into account the touch point position determined in step b) in the averaging of step c) or to take it into account less by weighting.

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