DE102010054257A1 - Method for determining the crosstalk behavior of a dual-clutch system - Google Patents

Abstract

The invention relates to a method for determining the crosstalk behavior of a double clutch system with two sub-clutches, the actuation of one of the sub-clutches influencing the transmittable torque of the other sub-clutch. The invention is characterized in that at least one touch point or changes in the touch point of at least one of the partial clutches is or are taken into account when determining the crosstalk behavior.

Description

The invention relates to a method for determining the crosstalk behavior of a dual-clutch system with two partial clutches, the actuation of one of the partial clutches influencing the transmittable torque of the other partial clutch.

From the German patent application DE 10 2008 031 954 A1 a method for controlling a dual clutch is known, wherein the elasticities of the dual clutch are coordinated so that, while a friction clutch is closed, the closing of the other friction clutch causes a force or force reduction at the one friction clutch. From the European patent EP 1 554 502 B1 a method for driving a double clutch is known in which a crosstalk is prevented, for example by a suitable torque influencing. In this case, for example, the changes in the clutch torques as a function of the torque of the other clutch can be taken directly into account. When performing an adaptation of parameters a Tastpunktverschiebung is considered by the crosstalk from the other clutch.

The object of the invention is to provide a method by which the crosstalk behavior of a dual clutch system with two partial clutches can be determined quickly, easily and / or as accurately as possible. In particular, the method according to the invention should enable a quantitative determination of the crosstalk.

The object is in a method for determining the crosstalk behavior of a dual clutch system with two partial clutches, wherein the actuation of one of the partial clutches affects the transmittable torque of the other sub-clutch, achieved in that at least one touch point or changes the Tastpunkts at least one of the partial clutches in determining the crosstalk behavior is or will be considered. The partial clutches are actuated by actuators. The influence of the actuator position of one sub-clutch on the transmittable torque of the other sub-clutch is also called crosstalk. In crosstalk, the transmittable torque no longer corresponds to a nominal torque. If the transmittable torque is greater or less than the nominal torque, it is called a positive or negative crosstalk. The inventive method is preferably carried out when commissioning dual clutch systems on a commissioning test. The touch point describes a defined actuator position, in which the partial coupling assigned to the respective actuator transmits a specific torque, for example three Newton meters. With a touch point change or touch point shift, the characteristic of the part coupling is shifted in parallel. The touch point can be determined via an evaluation of transmission input speeds.

A preferred embodiment of the method is characterized in that at least one coefficient of friction or changes in the coefficient of friction of at least one of the partial clutches is taken into account in determining the crosstalk behavior. The changes in the coefficient of friction, as well as the changes in the touch point, can be determined by a numerical analysis of measured data, which are determined in a test bench cycle.

A further preferred embodiment of the method is characterized in that corrected torques T ₁ and T _{2 are determined} by means of the following formulas: T ₁ = T _{1, nom} (x ₁ + a ₁ × x ₂ + b ₁ × (x ₂ ) ² ) T ₂ = T _{2, nom} (x ₂ + a ₂ × x ₁ + b ₂ × (x ₁ ) ² )

T _{1, nom} () and T _{2, nom} () are the nominal moments as functions of their actuator positions x ₁ and x ₂ . The constants a ₁ , b ₁ , a ₂ and b ₂ are model parameters. They are to be checked for every building condition. The values determined on the basis of the test bench measurements can be taken from a table.

A further preferred embodiment of the method is characterized in that the crosstalk behavior is determined by means of maps. The maps can be determined in a test cycle and / or in a driving cycle.

A further preferred embodiment of the method is characterized in that individual parameters are determined for a crosstalk model on a commissioning test bench by means of a special routine. The commissioning test stand is arranged, for example, at the end of the tape in the production of the coupling system.

A further preferred embodiment of the method is characterized in that the determined parameters for a later compensation of travel requirements during operation of the dual clutch system are stored in a control unit. The determined parameters can be stored, for example, in an EEPROM of the controller. EEPROM is the abbreviation for electrically erasable programmable read only memory. This means electrically erasable, programmable read-only memory.

A further preferred embodiment of the method is characterized in that the routine closes a partial clutch to a low drive torque, in which the most stable clutch torque is transmitted. An attempt is made to enter as little energy as possible into the clutch in order to exclude disturbing effects, such as heating of the clutch.

A further preferred embodiment of the method is characterized in that a defined slip is set between the drive side and the output side of the partial clutch, which is stabilized via a control. On the active part gearbox a favorable gear is engaged for the best possible measurement resolution. The choice of the gear depends on whether the torque measurement takes place on the engine side or on the transmission side.

A further preferred exemplary embodiment of the method is characterized in that a gear is not engaged on an active partial transmission and no gear is engaged on an inactive partial transmission. On the inactive part transmission is for example neutral preselected.

A further preferred embodiment of the method is characterized in that closed by the routine, the inactive part clutch on the inactive part transmission with a position ramp and then reopened. This process can be performed once or several times.

A further preferred embodiment of the method is characterized in that from a measurement of the drive torque and the current position of the inactive part clutch a characteristic M _Ü = f _Ü (x) is determined. M _Ü stands for the drive torque. f _Ü stands for the characteristic that depends on the coupling position x.

A further preferred exemplary embodiment of the method is characterized in that an estimated clutch position is determined from the inverse function of the characteristic curve. With the above-mentioned formula for the characteristic then results for the estimated position

ermittelt werden. Dabei sind die Position x₁ und die Kennlinie bekannt.A further preferred embodiment of the method is characterized in that parameters a _i and b _i from a minimization of the problem

be determined. The position x ₁ and the characteristic are known.

A further preferred embodiment of the method is characterized in that the opening and closing of the inactive part coupling is repeated several times. As a result, the quality of the characteristic can be improved.

Further advantages, features and details of the invention will become apparent from the following description in which an embodiment is described in detail.

In dual-clutch systems, the frictional connection between an internal combustion engine and a drive wheel is realized by two parallel torque transmission paths, each comprising a partial clutch and a partial transmission. The torque transmission paths are merged in the direction of the drive wheel via a differential.

During operation of a motor vehicle with such a dual-clutch system, a partial clutch is predominantly closed in various driving situations, a gear being engaged on the associated partial transmission. If you change the frictional connection of a partial transmission to the other, for example, in the first partial transmission, the first gear and driven with closed clutch and preselected in the second partial transmission, the second gear, the first partial clutch is opened in ramp form and the second partial clutch on the second partial transmission 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. Even small deviations in a clutch model compared to the real system can lead to torque peaks or torque holes that can disturb the ride comfort, for example, by a perceived by the driver, sensitive.

In the context of the present invention, it has been found that the crosstalk behavior of the partial clutches has a non-negligible influence, since the touch point of the respective other partial clutch and thus the clutch model changes substantially. At the beginning of a crossover circuit, one clutch is very far closed, while the other clutch is being closed. It was found that the closing clutch transmits more and more momentum than expected. In sum, this would lead to a momentum increase. At whole closed clutch must be expected so for example with a considerable touch point shift on the other part clutch.

The special arrangement with two parallel torque transmission paths in the dual clutch system allows the determination of the tactile points via the evaluation of the transmission input speeds, as described for example in the European patent EP 1 554 502 B1 is described. For this one drives on a partial transmission, while on the other partial transmission the gear is engaged 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, closed on a clutch torque. By comparing the requested and actually achieved clutch torque of the touch point and thus the model can be determined on the inactive coupling while driving and thus adapted.

In a control software for the dual clutch system, a compensation of the crosstalk behavior can be provided. In this case, the following dependency of the current clutch position can be used in order to obtain a moment via the clutch characteristic f M = f (x ~) (1) to determine.

Depending on the index of the clutch, this results in the current clutch positions. x ~ ₁ = x ₁ + a ₁ x ₂ + b ₁ x 2/2 x ~ ₂ = x ₂ + a ₂ x ₁ + b ₂ x 2/1

In this case, x ₁ and x ₂ correspond to the actuator positions. For the two partial clutches, the parameters a _i and b _{i must} be determined, where i is given in the quantity of the numbers 1 and 2.

The object of the present invention is the determination of individual parameters for a crosstalk model for each partial clutch by the clutch control software on the commissioning test stand, which is arranged for example at the end of the tape in the production of the coupling system. The parameters for the crosstalk model on the commissioning test stand are determined by means of a routine developed for this purpose and permanently stored in the memory of a control unit of the dual clutch system for a later compensation of the travel requirements during operation of the dual clutch system.

The routine closes a clutch on the start-up test bench or a transmission test bench to a low torque, in which the most stable possible clutch torque is transmitted. It is trying to enter as little energy in the clutch to eliminate disturbing effects, such as heating of the clutch.

The test stand adjusts a previously defined slip between a drive side and an output side of one of the partial clutches, wherein the slip is stabilized via a control. On the active part transmission the best possible measurement resolution is a favorable gear engaged. The choice of the gear depends on whether the torque measurement takes place on the engine side or on the transmission side.

On the inactive part gearbox no gear is engaged, so neutral pre-selected. The routine closes the inactive clutch on this transmission with a position ramp and then opens it again. From the measurement of the drive torque M _Ü and the current clutch position x of the inactive clutch, a characteristic curve M _Ü = f _Ü (x) (2) be determined. For an estimated position then applies

With the equation for the drive torque then results for the estimated position

berechnet werden, wobei die Position x₁ und die Kennlinie bekannt sind. Für eine bessere Ermittlung der Kennlinie f_Ü kann das Schließen und Öffnen der inaktiven Kupplung mehrmals wiederholt werden.The parameters a _i and b _i can then, for example, for the first partial clutch from the minimization of the problem

are calculated, the position x ₁ and the characteristic are known. For a better determination of the characteristic curve f _Ü , the closing and opening of the inactive coupling can be repeated several times.

The inventive method can be used for all applications in which the Tastpunktadaption is used on the evaluation of the transmission input shaft speed. These are in particular all applications with start-stop function, since an estimation of the engine torque offset by the absence of idle phases is impossible.

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 102008031954 A1 [0002]
• EP 1554502 B1 [0002, 0024]

Claims (10)

Method for determining the crosstalk behavior of a dual-clutch system with two partial clutches, the actuation of one of the partial clutches influencing the transferable torque of the other partial clutch, characterized in that at least one touch point or changes of the touch point of at least one of the partial clutches are taken into account in determining the crosstalk behavior, and / or that at least one coefficient of friction or changes in the coefficient of friction of at least one of the partial clutches are taken into account in determining the crosstalk behavior. A method according to claim 1, characterized in that corrected torques T ₁ and T ₂ are determined using the following formula: T ₁ = T _{1, nom} (x ₁ + a ₁ × x ₂ + b ₁ × (x ₂ ) ² ) T ₂ = T _{2, nom} (x ₂ + a ₂ × x ₁ + b ₂ × (x ₁ ) ² ), where T _{1, nom ()} and T _{2, nom () are} nominal moments as functions of their actuator positions x ₁ and x ₂ and the constants a ₁ , b ₁ , a ₂ and b _{2 are} model parameters. Method according to one of the preceding claims, characterized in that individual parameters are determined for a crosstalk model on a commissioning test bench by means of a special routine. A method according to claim 3, characterized in that the determined parameters for a later compensation of path requirements during operation of the dual clutch system are stored in a control device. A method according to claim 3 or 4, characterized in that the routine closes a partial clutch to a low drive torque, in which the most stable clutch torque is transmitted. A method according to claim 5, characterized in that between the drive side and the output side of the partial clutch, a defined slip is set, which is stabilized via a control. Method according to one of claims 3 to 6, characterized in that closed by the routine, the inactive part clutch on the inactive part transmission with a position ramp and then reopened. A method according to claim 7, characterized in that from a measurement of the drive torque and the current position of the inactive part clutch a characteristic M _Ü = f _Ü (x) is determined. A method according to claim 8, characterized in that an estimated clutch position from the inverse function of the characteristic curve is determined. Method according to claim 9, characterized in that parameters a1 and b1 result from a minimization of the problem

be determined.