DE102011081193A1 - Method for determining cross-talk behavior of dual clutch system in dual clutch transmission in powertrain of motor car, involves continuing cross-talk behavior determining process until no further reference torque is predetermined - Google Patents

Abstract

The method involves driving a clutch of an inactive sub-transmission toward a closed clutch in a partially opened position. A clutch of an active sub-transmission is driven in a position along a clutch traverse path. Rotational torque transferred from the latter clutch and/or a deviation of the torque from a reference torque is determined depending on the clutch position in which a predetermined reference torque is transferred as the torque by the latter clutch in the position such that cross-talk behavior determining process is continued until no further reference torque is predetermined.

Description

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

The invention serves to more precisely model the crosstalk behavior in dual clutch systems. In the context of this document, the terms dual-clutch system and dual-clutch transmission are used interchangeably. The term dual clutch system aims at the two clutches of the dual-clutch transmission. Such dual-clutch transmission, for example, from the DE 10 2010 024 941 A1 respectively. WO 2011/006466 A1 and numerous other documents. In the context of this document, that partial transmission is referred to as active in the double-clutch transmission, which has an engaged gear, which is not the neutral gear, the part of this transmission associated clutch of the dual-clutch transmission is referred to as the active clutch. Similarly, that sub-transmission is referred to as inactive, in which the neutral gear is engaged or the sub-transmission is in neutral, so no gear is engaged, this sub-transmission associated clutch of the dual-clutch transmission is referred to as the inactive clutch.

In dual-clutch systems, the adhesion between the engine and the wheel is realized by two parallel paths, each consisting of a clutch and a partial transmission. The paths are merged towards the wheel via the differential.

• – 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

• - Overlaps during the change of the power flow from one part to the other and to the
• - Tactile point determination via evaluation of the transmission input speeds.

Influence of the crosstalk behavior in case of overlapping during the change of the power flow from one partial transmission to the other.

In the various driving situations, a clutch is predominantly closed, wherein a gear is engaged on the associated partial transmission. If you change the frictional connection of one partial transmission to the other, for example, in the partial transmission 1 1st gear engaged and driven with the clutch closed and in the partial transmission 2 if the 2nd gear is preselected, the clutch becomes 1 ramp open and the clutch 2 on partial transmission 2 is closed in a ramp.

In the case of this so-called overlap, the two coupling moments in the sum ideally result in the applied engine torque. However, even small deviations in a clutch model in comparison to the real system can lead to torque peaks or torque holes, which can disturb the ride comfort, by a judder perceived by the driver, sensitive.

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 a crossover circuit, one clutch is very far closed, while the other clutch is being closed. The clutch to be closed transmits according to current knowledge usually always more moment than expected, in total, this would lead to an increase in torque. When the coupling is completely closed, it is necessary, for example, to with a not inconsiderable touch point shift of 1-2 mm on the other clutch.

Influence of the crosstalk behavior in the Tactile Point determination via evaluation of the

Transmission input speeds:

The special arrangement with two parallel paths in a dual-clutch transmission allows the determination of the tactile points on the evaluation of the transmission input speeds, such as in the DE 10 2010 024 941 A1 or the WO 2011/006466 A1 shown. To do this, you drive on a partial transmission while the gear is laid out on the other partial transmission and the clutch is open. By observing the speed curve of the transmission input shaft, in a first phase, is closed to a drag torque. Later in a second phase, when closing the clutch to a small moment, a clutch torque is closed. By comparing the requested and actually achieved clutch torque of the touch point and thus the model can be determined on the inactive clutch while driving and thus adapted.

If the crosstalk behavior of the clutches in the Taktpunktermittelung on the evaluation of the transmission input speeds at current building conditions not observed, then the touch point can not be determined in sufficient accuracy.

Well-known model for the crosstalk behavior:

A compensation of the crosstalk behavior is already known. In this case, the following dependency of the current clutch position x ~ is used to apply a torque via the clutch characteristic f M = f (x) (1) to determine.

Depending on the index of the coupling results in the process x ~ ₁ = x ₁ + α ₁ x ₂ + b ₁ x 2/2 x ~ ₂ = x ₂ + α ₂ x ₂ + b ₂ x 2/1

For use of this model, the parameters α _i and b _i with i ∈ {1; 2}. These parameters can be determined for all clutches depending on the accuracy requirements for modeling the crosstalk behavior at the belt end on a transmission test bench for each individual clutch or during development in advance. Such is also for example in the DE 10 2010 054 257 A1 or the WO 2011/076177 A1 as well as in the German patent application with the file number 10 2010 051 903.0 shown.

Investigations on the test bench show that the crosstalk behavior in reality behaves differently, as can be represented by the known crosstalk model. There are two striking weaknesses:

- Torque dependence of the crosstalk behavior:

The crosstalk behavior changes greatly with the moment that is transmitted via the active coupling. Measurable here is a change in the moment. In the known model it is assumed that the active clutch path changes depending on the inactive clutch. Changes due to fluctuating coefficient of friction are not taken into account in the model. The software merely stores the relationship between the required clutch position change of the active clutch as a function of the clutch position of the inactive clutch, which would be necessary to compensate for the actual crosstalk behavior. An increase of the crosstalk behavior with the moment of the active coupling can not be represented with this model.

- Crosstalk model of higher order:

The torque change due to crosstalk at a fixed clutch position of the active clutch is for the clutch 1 - Which is usually associated with the first gear - the dual clutch system by a dependency in the form of a parabola insufficient representation.

It is an object of the present invention to develop a more accurate model for modeling crosstalk behavior in dual clutch systems.

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

• a) die Kupplung des aktiven Teilgetriebes wird in eine Position entlang des Verfahrwegs der Kupplung gefahren, in der die Kupplung ein vorgegebenes Referenzmoment als Drehmoment überträgt,
• b) die Kupplung des inaktiven Teilgetriebes wird ausgehend von einer zumindest teilweise geöffnete Position in Richtung geschlossener Kupplung verfahren und das von der Kupplung des aktiven Teilgetriebes übertragene Drehmoment und/oder dessen Abweichung vom Referenzmoment wird in Abhängigkeit von der Position der Kupplung des inaktiven Teilgetriebes ermittelt,
• c) das Referenzmoment sowie das von der Kupplung des aktiven Teilgetriebes übertragene Drehmoment und/oder dessen Abweichung vom Referenzmoment wird in Abhängigkeit von der Position der Kupplung des inaktiven Teilgetriebes gespeichert,
• d) die Kupplung des inaktiven Teilgetriebes wird in die vollständig geöffnete Position verfahren und die Kupplung des aktiven Teilgetriebes wird in eine Position entlang des Verfahrwegs der Kupplung gefahren, in der die Kupplung des aktiven Teilgetriebes ein anderes, weiteres, vorgegebenes Referenzmoment als Drehmoment überträgt und das Verfahren wird in Schritt b) fortgesetzt bis keine weiteren Referenzmomente vorgegeben sind.

According to the invention, a method is provided for determining the crosstalk behavior of a dual clutch system in a dual clutch transmission in the drive train of a motor vehicle having a drive unit, wherein the dual clutch transmission comprises two partial transmissions, each partial transmission each having a friction clutch of the dual clutch system is assigned, which is arranged between each a partial transmission and the drive unit , wherein in a first, the active part transmission a gear is preselected and in the other, the inactive part transmission is selected neutral. According to the invention, it is provided that the following steps are carried out in succession:

• a) the clutch of the active sub-transmission is moved to a position along the travel of the clutch, in which the clutch transmits a predetermined reference torque as torque,
• b) the clutch of the inactive subtransmission is moved starting from an at least partially open position in the direction of the closed clutch and the torque transmitted by the clutch of the active subtransmission and / or its deviation from the reference torque is determined in dependence on the position of the clutch of the inactive subtransmission,
• c) the reference torque as well as the torque transmitted by the clutch of the active subtransmission and / or its deviation from the reference torque is stored as a function of the position of the clutch of the inactive subtransmission,
• d) the clutch of the inactive subtransmission is moved to the fully open position and the clutch of the active subtransmission is moved to a position along the travel of the clutch, in which the clutch of the active subtransmission transmits another, further, predetermined reference torque as torque and the Method is continued in step b) until no further reference moments are given.

In a preferred embodiment of the invention, it is provided that in step b), the clutch of the inactive subtransmission is moved in a ramp-shaped or stepped manner in the direction of the closed clutch.

In a further preferred embodiment of the invention, it is provided that in step b) the clutch of the inactive partial transmission is moved starting from the fully open position in the direction of the closed clutch.

In a further preferred embodiment of the invention, it is provided that in step b) the clutch of the inactive partial transmission is moved in the direction of the closed clutch until the clutch is completely closed.

In a further preferred embodiment of the invention, it is provided that the method is carried out at initial startup of the dual clutch system.

In a further preferred embodiment of the invention it is provided that the storage takes place in a non-volatile memory such as an EEPROM. The non-volatile memory receives its memory contents even if the supply voltage of the memory or the power supply is interrupted for a long time.

In a further preferred embodiment of the invention, it is provided that three reference moments are predetermined, wherein the reference moments are distributed over the torque range provided by the drive motor.

In a further preferred embodiment of the invention, it is provided that a reference torque from the torque range between 5 Nm and 15 Nm is specified and preferably about 10 Nm and / or a reference torque from the torque range between 40 Nm and 60 Nm is given and preferably about 50 Nm and / or a reference torque from the torque range between 80 Nm and 300 Nm is specified, and preferably about 110 Nm.

In another preferred embodiment of the invention, it is provided that the torque transmitted by the clutch of the active partial transmission and / or its deviation from the reference torque is stored in the form of a characteristic field as a function of the position of the clutch of the inactive partial transmission and in dependence on the reference torque.

In a further preferred embodiment of the invention, it is provided that the deviation of the torque transmitted by the clutch of the active subgear from the reference torque as a function of the position of the clutch of the inactive subgear as a function of polynomials of the first to nth order (quite rational functions n -ten degree), in particular as a function of polynomials of the second and / or third order is approximated, wherein the coefficients and parameters characteristic of the function are stored as a function of the reference moment. Let n be a natural number.

In a further preferred embodiment of the invention it is provided that the method is additionally performed at predetermined reference speeds and the map is additionally formed in dependence on the reference speed and / or the parameters characteristic of the function are additionally stored in dependence on the reference speed.

In a further preferred embodiment of the invention, it is provided that the rotational speed, the rotational speed of the drive unit.

In a further alternative embodiment of the invention, it is provided that the rotational speed, the clutch output rotational speed of the clutch of the active partial transmission, ie the transmission input rotational speed of the active partial transmission.

In a further alternative embodiment of the invention, it is provided that the rotational speed, the clutch output rotational speed of the clutch of the inactive partial transmission, ie the transmission input rotational speed of the inactive partial transmission is.

In a further alternative embodiment of the invention, it is provided that two or all three speeds are selected from the aforementioned three sources of rotational speeds, wherein an additional dependence on these two or three rotational speeds and corresponding maps and / or functions with the corresponding Dependencies are stored.

In a further preferred embodiment of the invention, it is provided that interpolation between characteristics of the map or between functions.

In a further preferred embodiment of the invention, it is provided that when characteristics and / or functions with respect to a parameter, in particular the reference speed, by scaling a characteristic and / or a function result from this, so when scaling a characteristic or a function with different Scaling factors essentially result in the other characteristics or the other functions, only the one characteristic and / or only the one function and the scaling factors are stored.

In a further preferred embodiment of the invention it is provided that the scaling is linear or non-linear and wherein the type of scaling is also stored.

In a further preferred embodiment of the invention, it is provided that from that in step c) in dependence on the position the coupling of the inactive subtransmission determined, transmitted from the clutch of the active subtransmission torque and / or its deviation from the reference torque, a necessary to compensate for the deviation from the reference torque - that is to compensate for the crosstalk - the clutch of the active subtransmission necessary change in position of the clutch of the active subtransmission Based on the current clutch characteristic of the clutch of the active sub-transmission is determined. In addition, it is provided that a map, the, or a set of functions that the determined change in position in dependence on the clutch position of the clutch of the inactive sub-transmission and / or the transmitted torque of the clutch of the active sub-transmission and / or its deviation from the reference torque of Clutch of the active sub-transmission and / or optionally of the reference speed as the basis for the compensation of the crosstalk behavior comprises, is stored.

In order to avoid the torque accuracy during the change of power transmission from one sub-clutch to the other harmful influences of the crosstalk behavior in a dual-clutch transmission, and to be able to provide a moment at the Tastpunktadaption on the evaluation of the transmission input speeds, which allows the Tastpunktadaption, it is necessary to use accurate model for the crosstalk behavior of the clutch for their compensation. Advantageously, such a model according to the invention can be provided. For the exact model according to the invention of the crosstalk behavior, a torque dependence of the active clutch is necessary, furthermore, especially when learning the parameters during the initial startup of the dual clutch system, instead of a characteristic field, a family of polynomials of the second or third order or higher is proposed Dodge order, since so are used in an advantageous manner memory resources better.

The solution of the problem is therefore to extend the model for the crosstalk by a torque dependence and to increase the order of the polynomials used.

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

They show in detail:

1 Torque change due to crosstalk for 3 moment supporting points (10 Nm (reference numeral 110 ), 55 Nm (reference numeral 155 ), 108 Nm (reference numeral 1108 ) for coupling 1 , Measuring points approximated with a 2nd order polynomial.

2 Torque change due to crosstalk for 3 moment supporting points (10 Nm (reference numeral 210 ), 52 Nm (reference numeral 252 ), 102 Nm (reference numeral 2102 )) for coupling 2 , Measuring points approximated with a 2nd order polynomial.

The model of the crosstalk behavior should result in a compensation in a clutch position shift. For this purpose, a model is assumed which represents a torque change due to the crosstalk at the active clutch M _{U, active} depending on the torque M _active currently transmitted via the clutch and the position of the inactive clutch x _inactive , resulting in the relationship M _{Ü , active} = f _Ü (M _active , x _inactive ).

The functional relationship f _Ü is stored in the software and converted into a clutch position change depending on the current clutch characteristic. The functional relationship f _Ü can in the simplest case be represented by a characteristic diagram. At least 3 interpolation points are used for the torque dependency and at least 5 interpolation points are assumed for the position dependency.

The determination of the functional relationship f _Ü must either be determined individually for each clutch at the end of the belt and stored in the EEPROM for use in normal driving, or it is assumed and calibrated for all clutches a firm relationship. For this purpose, the active clutch can be moved to a fixed coupling position in which a moment is transmitted while the inactive clutch is still open. This torque transmitted by the active clutch serves as reference moment. The inactive clutch is then closed ramped / stepped and the transmitted torque on the active clutch changes. The changes are then applied f _Ü for the fixed reference torque in the characteristic field, which is the active moment in the characteristic diagram. For the remaining moment support points of the active clutch torque in the map, this process is repeated.

In the 1 and 2 are measured data in which the measuring points are approximated with a polynomial of 2nd order. You can clearly see in 2 that for the curve 2102 a better approximation could be achieved by a 3rd order polynomial.

Functional group as an alternative to the map:

For a fixed torque support point with respect to the active clutch, the dependence of the torque change on the clutch position of the inactive clutch can also be approximated as a function in the form of a polynomial; polynomials of the second or third order are suitable for this purpose

For coupling 1 This applies to a 30 Nm interpolation point with a 2nd order polynomial M _{Ü, 1} = f _{Ü, 30Nm} (x ₂ ) = α ₁ x 2/2 + b ₁ x ₂ + c ₁ , for a 50 Nm interpolation point in a 3rd order polynomial M _{Ü, 1} = f _{Ü, 50Nm} (x ₂ ) = d ₁ x _3/2 + e ₁ x 2/2 + f ₁ x ₂ + g ₁ .

Normally the moment disappears when the clutch is inactive (x = 0), then it applies c ₁ = 0 or g ₁ = 0.

Speed-related effects in the measured crosstalk torque:

The crosstalk of the double clutch is due to the design dependent on the speed, since the rotating components are subject to centrifugal force. At different speeds, the determination of the crosstalk torque can thus be carried out and compared with the determined characteristic field or the determined set of functions for low speeds. From the comparison, a scaling of the low speed map may be derived for use at higher speeds. This scaling can also be nonlinear. For different speeds and separate maps can be stored and interpolated between them.

Determination of a position shift:

The model presented here determines a change in the torque transmitted on a clutch as a function of the clutch position of the other, inactive clutch. Based on this moment, depending on the current clutch characteristic, a position change for a compensation of the effect is concluded. It is useful to directly determine the necessary for the compensation clutch position shift and a map, the, or a group of functions, the change in position depending on the clutch position of the inactive clutch, the torque of the active clutch and optionally the speed as the basis for the compensation determine.

The inventive method is advantageously used in all applications in which the Tastpunktadaption is carried out on the evaluation of the transmission input shaft speed. These are in particular all applications with stop-start function, since an estimation of the engine torque offset by the absence of idle phases is impossible. An adaptation of the touch point without precise engine torque offset is practically impossible with the previous model-based touch point adaptation.

In order to avoid damaging influences on the torque accuracy during the change of the power transmission from one sub-clutch to the other, and to be able to provide a moment at the touch point adaptation via the evaluation of the transmission input speeds, which allows the touch point adaptation, it is necessary to have an exact model for the crosstalk behavior to use the clutch for compensation. For an exact model of the crosstalk behavior, a torque dependency on the active clutch is necessary, furthermore, especially when learning the parameters during commissioning, it is proposed to use a family of polynomials of the second or third order instead of a characteristic map, since here there is memory Resources are better used.

LIST OF REFERENCE NUMBERS

XTalk Cl1

Crosstalk of clutch 1

Position Cl1

Position of clutch 1

XTalk Cl2

Crosstalk of clutch 2

Position Cl2

Position of clutch 2

110

 Data points and approximation with polynomial 2nd order for reference torque 10 Nm

155

 Data points and approximation with polynomial 2nd order for reference torque 55 Nm

1108

 Data points and approximation with polynomial 2nd order for reference torque 108 Nm

210

 Data points and approximation with polynomial 2nd order for reference torque 10 Nm

252

 Data points and approximation with polynomial 2nd order for reference torque 52 Nm

2102

 Data points and approximation with polynomial 2nd order for reference torque 102 Nm

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• DE 102010024941 A1 [0002, 0010]
• WO 2011/006466 A1 [0002, 0010]
• DE 102010054257 A1 [0014]
• WO 2011/076177 A1 [0014]
• DE 102010051903 [0014]

Claims (10)

A method for determining the crosstalk behavior of a dual clutch system in a dual clutch transmission in the drive train of a motor vehicle having a drive unit, wherein each partial transmission is associated with a respective friction clutch of the dual clutch system, which is arranged between each of a partial transmission and the drive unit, wherein in one the first, the active part transmission is preselected a gear and is selected in the other, the inactive partial transmission neutral, characterized in that the following steps are carried out successively: a) the clutch of the active sub-transmission is moved to a position along the travel of the clutch, in the the clutch transmits a predetermined reference torque as torque, b) the clutch of the inactive partial transmission is moved starting from an at least partially open position in the direction of the closed clutch and that of the Kupp The torque transmitted to the active partial transmission and / or its deviation from the reference torque is determined as a function of the position of the clutch of the inactive partial transmission, c) the reference torque and the torque transmitted by the clutch of the active partial transmission and / or its deviation from the reference torque is dependent stored in the position of the clutch of the inactive subtransmission, d) the clutch of the inactive subtransmission is moved to the fully open position and the clutch of the active subtransmission is moved to a position along the travel of the clutch, in which the clutch of the active subtransmission another , further predetermined reference torque transmits as torque and the method is continued in step b) until no further reference moments are given. A method according to claim 1, characterized in that in step b) the coupling of the inactive subtransmission is moved rampwise or stepwise in the direction of closed clutch and / or that in step b) the clutch of the inactive subtransmission, starting from the fully open position in the direction of closed clutch is moved and / or that in step b) the coupling of the inactive part of the transmission is moved in the direction of the closed clutch until the clutch is fully closed. Method according to one of claims 1 to 2, characterized in that the method is carried out at first commissioning of the dual clutch system and / or that the storage takes place in an EEPROM. Method according to one of claims 1 to 3, characterized in that three reference moments are predetermined, wherein the reference moments are distributed over the torque range provided by the drive motor and / or wherein a reference torque from the torque range between 5 Nm and 15 Nm is given and preferably about 10 Nm and / or wherein a reference torque from the torque range between 40 Nm and 60 Nm is specified and preferably about 50 Nm and / or wherein a reference torque from the torque range between 80 Nm and 300 Nm is specified and preferably about 110 Nm. Method according to one of Claims 1 to 4, characterized in that the torque transmitted by the clutch of the active partial transmission and / or its deviation from the reference torque is stored in the form of a characteristic field as a function of the position of the clutch of the inactive partial transmission and in dependence on the reference torque , Method according to one of Claims 1 to 5, characterized in that the deviation of the torque transmitted by the clutch of the active subtransmission from the reference torque as a function of the position of the clutch of the inactive subtransmission as a function of first to nth order polynomials ( 110 . 155 . 1108 . 210 . 252 . 2102 ), in particular as a function of polynomials of the second and / or third order ( 110 . 155 . 1108 . 210 . 252 . 2102 ) is approximated, where for the function ( 110 . 155 . 1108 . 210 . 252 . 2102 ) characteristic parameters are stored as a function of the reference moment. Method according to one of claims 1 to 6, characterized in that the method is additionally carried out at predetermined reference speeds and the map is additionally formed in dependence on the reference speed and / or the parameters characteristic of the function are additionally stored in dependence on the reference speed. Method according to one of claim 7, characterized in that the rotational speed, the rotational speed of the drive unit and / or the clutch output speed of the clutch of the active sub-transmission or the clutch output speed of the clutch of the inactive subtransmission is or two or all three speeds are, the additional dependency correspondingly consists of these two or three speeds and corresponding maps and / or functions are stored. Method according to one of claims 1 to 8, characterized in that when characteristics and / or functions relating to a parameter, in particular the reference speed, by scaling a characteristic and / or a function result from this, only the one characteristic and / or only the one Function are stored, wherein the scaling is linear or non-linear and / or wherein the type of scaling is also stored. Method according to one of claims 1 to 9, characterized in that from the determined in step c) depending on the position of the clutch of the inactive subtransmission, transmitted from the clutch of the active subtransmission torque and / or its deviation from the reference torque, one for compensation the deviation from the reference torque of the clutch of the active sub-transmission necessary position change of the clutch of the active sub-transmission is determined based on the current clutch characteristic of the clutch of the active sub-transmission and that a map, the, or a set of functions, the determined change in position as a function of the clutch position of the clutch the inactive sub-transmission and / or the transmitted torque of the clutch of the active sub-transmission and / or its deviation from the reference torque of the clutch of the active sub-transmission and / or optionally of the reference speed to compensate for the crosstalk behavior includes, is stored.

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