Method for calibrating clutch control

Abstract

The invention relates to a method for calibrating clutch control. The drive train has a motor (14) designed as an electric motor. The output end of the drive train is stopped (32), and the motor (14) is operated (36) with the value for the first operating variable. Then, the clutch is actuated (54, 66) with a first value for the clutch actuation amount, and a first value of a second operating variable of the motor is detected. Furthermore, the clutch is actuated (64) with a second value for the clutch actuation amount, and a second value of a second operating variable of the motor (14) is detected. Clutch characteristic data are ascertained as a function of the detected first value and the detected second value of the second operating variable.

Description

Technical Field

[0001] The present invention relates to a method for calibrating the clutch control of a drive train of a motor vehicle, wherein the drive train has a motor configured as an electric motor. Background Art

[0002] To optimize the control of a vehicle transmission, calibration routines are used, and thus, for example, compensation for component tolerances and manufacturing tolerances should be performed. Thereby, for example, it should be compensated for the situation that different clutches of the same series may transmit completely different torques under the same operation. Otherwise, due to their respective tolerances, these clutches may be closed to different degrees under the same control. However, here, the actual pressing force in the clutch is usually not detected because measuring the pressing force is extremely costly. In most motor vehicles, sensors required for this are not even installed. Instead, for calibration, only the filling equilibrium pressure is known, for example. For this purpose, the clutch is operated with different pressure levels, and based on the detected rotational speed, it is known from when the clutch starts to transmit a torque greater than the drag torque. However, the relationship thus obtained between the actuation of the clutch and the torque that can be transmitted is very small. In addition, calibration may be performed, for example, only with a single operating point.

[0003] Alternatively, calibration can also be performed on a test bench immediately after the production of the clutch or transmission. However, this calibration itself is already costly and expensive. In addition, recalibration can only be performed later in a workshop, for example, when servicing the motor vehicle. Therefore, for example, the motor vehicle itself cannot respond to the aging of the clutch oil by means of a new calibration. Summary of the Invention

[0004] A first aspect relates to a method for calibrating the clutch control of a drive train. This calibration can cause a change in the control parameters of one or more clutches of the drive train. The drive train has at least one clutch. The clutch can be configured as a diaphragm clutch, for example. The clutch can be actuated, for example, by means of an electrohydraulic pressure regulating valve. By energizing the pressure regulating valve, the actuation pressure of the clutch proportional to the energization can be adjusted. However, depending on, for example, manufacturing tolerances, the proportional relationship between the energization and the actuation pressure may be different in clutches of the same type. The drive train can be configured to generate and transmit driving force for a motor vehicle. The drive train has a motor configured as an electric motor. The electric motor can be configured as a synchronous motor or an asynchronous motor, for example. The motor can be, for example, a traction motor of the motor vehicle. The motor vehicle can be configured as a passenger vehicle, construction machinery, or agricultural machinery, for example.

[0005] The method has: stopping the driven end of the drive train. The driven end can be, for example, the driven axle or output shaft of the drive train. The stopping can be accomplished, for example, by means of a parking brake or a service brake. If there are multiple clutches, then all clutches in the power flow from the motor to the driven end that should not be calibrated can additionally be fully closed. These clutches can, for example, be pressurized to the maximum extent and thus provide an almost rotation-resistant connection.

[0006] The method has: operating the motor with a value for a first operating parameter. This value can be, for example, a predefined value. The operating parameter can be, for example, the power, speed or torque of the motor. In the case of an electric motor, the respective operating parameter can be detected and predefined with high quality. For example, in the case of an electric motor, the torque can be adjusted with high precision and maintained even under different loads. The torque of the electric motor can be present, for example, as a measured parameter in the inverter of the drive train. Thus, no additional sensors are required. The operating parameter can be transmitted, for example, in the vehicle data bus, such as the CAN bus, to the ECU, such as the transmission ECU. Therefore, for performing the calibration method, no structural adaptation of the drive train is required and no additional components that are not required during normal clutch operation or driving operation are needed.

[0007] The method has: operating the clutch with a first value for the clutch operating quantity. The clutch can be operated, for example, while the motor is operating with a value for the operating parameter. The clutch operating quantity can be a control parameter for operating the clutch. The clutch operating quantity can be, for example, the voltage or current used to energize the pressure regulating valve of the clutch. By operating, the clutch is operated with a pressure corresponding to the first value. Then, the clutch is, for example, partially closed accordingly. Then, the clutch can transmit a torque corresponding to the first value of the clutch operating quantity.

[0008] The method has: detecting a first value of a second operating parameter of the motor when the clutch is operated with the first value. The second operating parameter can be a parameter corresponding to the power of the motor, and this second operating parameter is different from the first operating parameter. From this, the state of the clutch when it is operated with the first value of the clutch operating quantity can be inferred. This state can be, for example, the transmissible torque, which corresponds to the first value of the clutch operating quantity. The detection can be performed, for example, by means of the drive train. For example, the torque required to maintain a predefined speed can be detected by means of the motor or alternatively or additionally by means of the inverter. This torque corresponds to the transmissible torque of the clutch due to the driven end of the drive train being stopped, optionally minus the respective drag torque in the drive train. Alternatively, for example, the speed that occurs at the motor under a predefined torque can be detected. In summary, the degree of operation of the clutch can be determined in this way.

[0009] The method has: actuating the clutch with a second value of the clutch actuation quantity. The second value of the clutch actuation quantity is different from the first value. The second value of the clutch actuation quantity can be, for example, greater than the first value. The method has: detecting a second value of a second operating parameter of the motor when actuating the clutch with the second value. Thus, a second operating point of the clutch can be determined. When actuating the clutch with the second value of the clutch actuation quantity and detecting the second value of the second operating parameter of the motor, the driven end of the drive train can also be blocked and the motor can also be operated with a value of a first operating parameter for the motor.

[0010] Optionally, additional operating points for calibration can also be taken into account. For this purpose, the clutch can be actuated, for example, with a third value of the clutch actuation quantity and optionally additional values. Then, correspondingly, a third value and optionally additional values of the second operating parameter for the motor can be detected when actuating the clutch correspondingly.

[0011] Optionally, the method can be repeated for different values of the first operating parameter. For example, it can be ascertained what torque can be transmitted at a first level of the motor speed and at a second level of the motor speed different from the first level. Thus, additional operating points can be ascertained and additional data for calibration can be generated and taken into account. In addition, different clutch control parameters or clutch control characteristic curves can be calibrated for different speeds in this way.

[0012] The method has: ascertaining clutch characteristic data as a function of a detected first value and a detected second value of the second operating parameter. These clutch characteristic data can be used for calibrating the clutch control. For example, the relationship between the clutch actuation quantity and the torque that can be transmitted by the clutch can be ascertained by interpolation and, if more than two operating points are determined, by curve fitting. This relationship can be stored, for example, by the transmission control unit and used for clutch control. Thus, the clutch characteristic data can have a characteristic curve. The clutch control characteristic curve can be changed, for example, as a function of the ascertained clutch characteristic data. To ascertain the clutch characteristic data, additional characteristic parameters can optionally be taken into account, such as the value of the first operating parameter for the motor, the first value of the clutch actuation quantity, and the second value of the clutch actuation quantity.

[0013] In a further embodiment of the method, it can be provided that the first operating parameter is the speed of the motor and the second operating parameter is the torque of the motor. The motor can thus be controlled at least during calibration by means of the speed. Thus, for example, the torque that can be transmitted by the clutch can be ascertained by means of the current required to maintain the motor speed. The calibration can thus be particularly simple and accurate.

[0014] In a further embodiment of the method, it can be provided that the first operating parameter is the torque of the motor and the second operating parameter is the rotational speed of the motor. The motor can thus be controlled by torque at least during calibration. Thus, an overload of the clutch can be reliably avoided during calibration.

[0015] In a further embodiment of the method, it can be provided that, when the clutch is actuated, the respective value of the clutch actuation quantity is adjusted in order to achieve the respective predetermined target parameter for the second operating parameter. Thus, instead of, for example, measuring the torque required to maintain a predetermined rotational speed at a predetermined value of the clutch actuation quantity, the clutch actuation quantity is adjusted in order to achieve, for example, a predetermined torque for the motor at a predetermined rotational speed. This calibration method can result in a particularly low load on the motor. This adjustment can be used, for example, only for the values of the clutch actuation quantity, such as a first value or a second value. However, this adjustment can also be used for more than one value or all values of the clutch actuation quantity.

[0016] In a further embodiment of the method, it can be provided that, before the clutch is actuated with the respective value of the clutch actuation quantity, a rapid filling of the clutch is carried out. The rapid filling can be the filling of the hydraulic actuator of the clutch before the actual actuation. Thereby, the actuator can be vented. During the rapid filling, the pressure regulating valve is, for example, opened particularly wide. The rapid filling can allow calibration to be carried out particularly quickly. In addition, the standardized actuation method used also during normal operation can thus be used to actuate the clutch during calibration. The duration of the rapid filling can be, for example, fixedly predetermined or determined within the scope of the calibration method. The rapid filling can be carried out before each actuation of the clutch during the calibration process or can also be carried out only during some of the actuations. After the rapid filling, the piston of the clutch may not yet be in contact with the diaphragm of the clutch and, alternatively or additionally, the vent gap may not yet have been eliminated.

[0017] In a further embodiment of the method, it can be provided that a filling equalization of the clutch is carried out before the clutch is actuated with the respective value of the clutch actuation quantity. Thereby, for example, the remaining oil quantity remaining in the actuator of the clutch can be taken into account. The filling equalization can be the filling of the hydraulic actuator of the clutch before the actual actuation and after the rapid filling. A duration can also be predetermined for the filling equalization. During the filling equalization, the pressure regulating valve can, for example, be opened less wide than during the rapid filling in order to avoid accidental actuation and the start of friction in the clutch. After the filling equalization, the clutch piston can be brought into contact at the minimum clutch torque. The stop of the driven end can, for example, only be carried out after the first filling equalization.

[0018] In a further embodiment of the method, it can be provided that, for the first time, the clutch is actuated starting from a less-actuated clutch with a first value for the clutch actuation quantity, and for the second time, the clutch is actuated starting from a more-actuated clutch with the first value for the clutch actuation quantity. The first value can be less than the second value here and the clutch is thus actuated less strongly. For example, for the first time, the clutch can be actuated with the first value after filling equalization, and for the second time, the clutch can be actuated after actuating the clutch with a second value for the clutch actuation quantity. Thereby, the hysteresis during calibration can be detected, where only three instead of four measurements of the operating point may be required. Depending on whether the clutch is adjusted in the direction of its disengaged position or in the direction of its engaged position, the relationship between the actuation quantity and the torque that can be transmitted at the clutch can be different. Thus, the relationship can be determined for the two adjustment directions with correspondingly little effort. Then, two corresponding characteristic curves can be determined, or for example, a characteristic curve with a hysteresis loop can be determined.

[0019] In a further embodiment of the method, it can be provided that the method has the step of detecting a further value of a second operating parameter of the motor when the clutch is not actuated. Thus, for example, the drag torque can be determined. The drag torque can be caused by friction in the drive train and alternatively or additionally by the minimum torque transmission that occurs when the clutch is fully disengaged. The drag torque does not correspond, for example, to the torque that can be transmitted at the clutch and can be excluded, for example, during clutch control. The determination of the clutch characteristic data can be carried out depending on the further detected value of the second operating parameter. This further value can be subtracted, for example, from other detected values of the second operating parameter in order to determine the torque that can be transmitted by the clutch. Thus, the respective characteristic curve for clutch control can be offset or corrected with the drag torque.

[0020] In a further embodiment of the method, it can be provided that the method has the step of changing the clutch control depending on the determined clutch characteristic data. For example, the respective control parameters of the clutch control can be changed, and alternatively or additionally, the control characteristic curve can be changed. For example, the clutch control can thus be calibrated once when the motor vehicle is put into operation. But the clutch control can also be adapted during the service life. For example, the method for calibration can be carried out periodically. Calibration can be carried out, for example, after a predetermined mileage, after a predetermined time, or at each vehicle start.

[0021] In a further embodiment of the method, it can be provided that the clutch is monitored by means of a calibration method. For this purpose, the clutch characteristic data obtained can be compared with the previously obtained clutch characteristic data or specified clutch characteristic data. If the deviation is greater than a threshold value, it can be output, for example, as a fault notification. This fault notification can signal to the user, for example, that the clutch needs maintenance. For example, the clutch wear can also be determined based on the obtained clutch characteristic data or a change in the obtained clutch characteristic data.

[0022] In a further embodiment of the method, it can be provided that the clutch characteristic data has a correlation between the clutch actuation quantity and the torque that can be transmitted by the clutch. Thus, the clutch can be controlled based on the desired transmissible torque.

[0023] In a further embodiment of the method, it can be provided that the clutch characteristic data has a friction value. For example, it can be determined by means of a calibration method which friction value the clutch currently has. Thereby, changes in the clutch oil and at the clutch friction linings can be taken into account.

[0024] In a further embodiment of the method, it can be provided that the clutch characteristic data has a clutch hysteresis. Thereby, the clutch control can be calibrated in a manner matching the adjustment direction of the clutch.

[0025] In a further embodiment of the method, it can be provided that the clutch characteristic data has a clutch wear characteristic value. The clutch wear characteristic value can be, for example, proportional to the transmissible torque and can be calculated as a percentage deviation from a specified value. The clutch wear characteristic value can be determined, for example, by means of the average deviation at all the obtained operating points during calibration or by means of the maximum deviation at all the obtained operating points.

[0026] In a further embodiment of the method, it can be provided that the method further has the step of: detecting the clutch temperature and obtaining the clutch characteristic data depending on the detected clutch temperature. Thereby, it can be taken into account during calibration that the clutch temperature has a significant influence on the friction in the clutch and thus on the transmissible torque. In addition, the calibration and the clutch control can also be carried out depending on the temperature. The clutch temperature can be, for example, the temperature of the friction linings in the clutch or the oil temperature.

[0027] The second aspect relates to a transmission controller, which is configured to execute the method according to the first aspect. Respective additional features, embodiments, and advantages result from the description of the first aspect. Conversely, the features, embodiments, and advantages of the second aspect also represent the features, embodiments, and advantages of the first aspect. The transmission controller may be configured to manipulate respective clutches of a motor vehicle. The transmission controller may be configured to transfer respective control signals to a clutch actuator, a motor controller of the motor vehicle, and a braking facility of the motor vehicle. The transmission controller may thus, for example, stop a driven end of a drive train of the motor vehicle, predetermine a value of a first operating parameter for the motor, and predetermine a value of a clutch actuation quantity for manipulating the clutch. In addition, the transmission controller may also be configured to receive a status signal from the motor controller. For example, a currently detected value of a second operating parameter of the motor may thus be transferred to the transmission controller. In addition, the transmission controller may also be configured to ascertain clutch characteristic data depending on a first detected value and a second detected value of the second operating parameter.

[0028] The third aspect relates to a system, which is configured to execute the method according to the first aspect. Respective additional features, embodiments, and advantages result from the description of the first aspect. Conversely, the features, embodiments, and advantages of the third aspect also represent the features, embodiments, and advantages of the first aspect. Description of the Drawings

[0029] Figure 1 A system is schematically illustrated by means of which the clutch control of a drive train of a motor vehicle can be calibrated;

[0030] Figure 2 A method for ascertaining an operating point during calibration of the clutch control is schematically illustrated;

[0031] Figure 3 The manipulation of the clutch for calibrating the clutch control is illustrated in a diagram. Detailed Description of the Invention

[0032] Figure 1System 10 is shown, which is configured for calibrating the clutch control of a drive train of a motor vehicle. System 10 has a brake 12, which is configured to stop the driven end of the drive train. System 10 has a motor 14 configured as an electric motor and a transmission 16, which is configured to transfer the driving force from the motor 14 to the driven end. The transmission 16 has only a single clutch in the illustrated example, which is configured as a diaphragm clutch in the illustrated example. System 10 has an inverter 18, which controls the power supply to the motor 14 via an energy source 20. The inverter 18 is furthermore configured to detect the respective uncontrolled operating parameters of the motor 14. In addition, system 10 also has a transmission controller 22 configured as an ECU. The transmission controller 22 is configured to control the clutch of the transmission 16 by adjusting the current for a pressure regulating valve. In addition, in one embodiment, the transmission controller 22 is also configured to detect the clutch temperature. In addition, the transmission controller 22 can also prescribe a setpoint for the motor speed and an alternative or additional setpoint for the motor torque for the inverter 18. In addition, the transmission controller 22 can also receive the current value of the motor speed and an alternative or additional current value of the motor torque from the inverter 18.

[0033] In the illustrated example, the motor 14 is speed-controlled. Thus, the inverter 18 prescribes a value for the speed as a first operating parameter for the motor 14 and accordingly regulates the power supply. The inverter 18 derives the value of the motor torque as a second operating parameter from the required power supply. Thus, if the motor 14 runs at a fixed speed prescribed by the transmission controller 22 during calibration and the brake 12 stops the driven end, the detected motor torque corresponds to the torque that can be transmitted by the clutch in the transmission 16.

[0034] Figure 2Disclosed is a method for determining an operating point during clutch control for calibrating a clutch of a transmission 16. Calibration is activated in step 30. The driven end is locked by means of a brake 12 in step 32. Quick filling and filling equalization are calibrated in step 34. By means of quick filling and filling equalization, the piston of the clutch can be brought into contact with the diaphragm, while the clutch is fully disengaged. In step 36, a fixed set speed is predefined for a motor 14 by a transmission controller 22. In response, an inverter 18 controls the power supply such that the motor 14 maintains this set speed. In step 38, the motor torque generated thereby is detected by the inverter 18 and transmitted to the transmission controller 22. This detected motor torque corresponds to the drag torque when the clutch is disengaged. In step 40, the clutch is controlled by the transmission controller 22 with a value for the clutch actuating quantity in order to actuate the clutch accordingly. The torque generated by the motor 14 when actuating the clutch with the value of the clutch actuating quantity is also detected. This results in the respective operating time points at which the torque transmissible via the clutch corresponding to the value of the clutch actuating quantity is detected. Step 40 can be repeated several times in order to determine the corresponding data for further operating points. The respective data thus collected are used in step 42 to determine clutch characteristic data. In a simple embodiment, the data of two operating points are used to generate a straight line as the clutch control characteristic curve. In step 44, the determined clutch characteristic data are stored by the transmission controller 22 or clutch control calibrated with the clutch characteristic data is carried out.

[0035] Figure 3 An embodiment for actuating a clutch or energizing a pressure regulating valve for actuating a clutch for calibrating clutch control is illustrated in a diagram. The current in mA is plotted on the ordinate. The time profile in seconds is plotted on the abscissa.

[0036] During calibration, the motor 14 is operated with a predetermined value for the motor speed as the first operating parameter. In region 48, the clutch is disengaged and the driven end is stopped by the brake 12. The drag torque is ascertained. A first quick fill is performed in region 50 and fill equalization is performed in region 52. Immediately thereafter, in region 54, the clutch is actuated with a first value for the clutch actuation quantity, i.e., a specific quantity of the current passing through the pressure regulating valve. The torque required to maintain the predetermined value for the motor speed is detected as a first value of the second operating parameter for the motor 14. Immediately thereafter, in region 56, the clutch is energized again with the value of the clutch actuation quantity during fill equalization and the clutch is thus disengaged again. The piston of the clutch remains in contact with the diaphragm at this time. In one embodiment, the torque required to maintain the predetermined value for the motor speed is detected as the value of the second operating parameter for the motor 14 in order to ascertain the point of hysteresis of the clutch control.

[0037] Immediately thereafter, in region 58, the actuator of the clutch is completely emptied and a waiting period is awaited. Thereafter, a quick fill is performed again in region 60 and fill equalization is performed in region 62. Immediately thereafter, in region 64, the clutch is actuated with a second value for the clutch actuation quantity, which second value is greater than the first value of the clutch actuation quantity. The torque required to maintain the predetermined value for the motor speed is detected as a second value of the second operating parameter for the motor 14. Immediately thereafter, in region 66, the clutch is actuated again with the first value of the clutch actuation quantity and the clutch is thus slightly disengaged again. In one embodiment, the torque required to maintain the predetermined value for the motor speed is detected as a further value of the second operating parameter for the motor 14 in order to ascertain a further point of hysteresis of the clutch control. Immediately thereafter, in region 68, the clutch is energized again with the value of the clutch actuation quantity during fill equalization and the clutch is thus completely disengaged again. The piston of the clutch remains in contact with the diaphragm at this time. In one embodiment, the torque required to maintain the predetermined value for the motor speed is detected as the value of the second operating parameter for the motor 14 in order to ascertain a further point of hysteresis of the clutch control.

[0038] Immediately thereafter, in region 70, the actuator of the clutch is completely emptied. Then, in one embodiment, the measurement for calibration is ended. In another embodiment, a waiting period is awaited and then further operating points at other speed levels are ascertained. After waiting for a period of time, the motor 14 is operated with other predetermined values for the motor speed as the first operating parameter and the foregoing regions 50 to 68 are traversed again. In one embodiment, these regions are repeated for a plurality of different speed levels.

[0039] List of reference numerals

[0040] 10 System

[0041] 12 Brake

[0042] 14 Motor

[0043] 16 Transmission

[0044] 18 Inverter

[0045] 20 Energy Source

[0046] 22 Transmission Controller

[0047] 30 Step: Activate Calibration

[0048] 32 Step: Stop the Driven End

[0049] 34 Step: Calibrate Fast Filling and Filling Equilibrium

[0050] 36 Step: Preset a Fixed Given Rotational Speed

[0051] 38 Step: Transfer the Motor Torque to the Transmission Controller

[0052] 40 Step: Control the Clutch with a Value

[0053] 42 Step: Obtain Clutch Characteristic Data

[0054] 44 Step: Store the Clutch Characteristic Data

[0055] 48 Area: Disconnect the Clutch and Stop the Driven End

[0056] 50 Area: First Fast Filling

[0057] 52 Area: Filling Equilibrium

[0058] 54 Area: Operate the Clutch with the First Value

[0059] 56 Area: Disconnect the Clutch

[0060] 58 Area: Completely Drain the Actuator and Wait for a Period of Time.

[0061] 60 Area: Re-Fast Filling

[0062] 62 Area: Filling Equilibrium

[0063] 64 Area: Operate the Clutch with the Second Value

[0064] 66 Area: Operate the Clutch with the First Value

[0065] 68 Area: Completely Disconnect the Clutch

[0066] 70 Area: Completely Drain the Actuator

Claims

1. A method for calibrating a clutch control of a drive train of a motor vehicle, wherein: The drive train has a motor (14) designed as an electric motor, and the method comprises at least the following steps: - stopping the driven end of the drive train (32); - operating the motor (14) with a value for a first operating variable; - actuating (54, 56) the clutch using a first value for a clutch actuation variable; - detecting a first value of a second operating variable of the motor (14) when the clutch is actuated with the first value; - actuating (64) the clutch using a second value for the clutch actuation variable; - detecting a second value of a second operating variable of the motor (14) when the clutch is actuated with the second value; and - clutch characteristic data are determined (42) as a function of the detected first value and the detected second value of the second operating variable.

2. The method according to claim 1, characterized in that The first operating variable is the rotational speed of the motor (14), and the second operating variable is the torque of the motor (14).

3. The method according to claim 1, characterized in that The first operating variable is the torque of the motor (14), and the second operating variable is the rotational speed of the motor (14).

4. The method according to any one of the preceding claims, characterized in that When the clutch is actuated, the respective value for the clutch actuation variable is controlled in order to achieve the respective predefined target variable for the second operating variable.

5. The method according to any one of the preceding claims, characterized in that Before the clutch is actuated with the respective value for the clutch actuation variable, the clutch is quickly filled (50, 60).

6. The method according to any one of the preceding claims, characterized in that Before the clutch is actuated with the respective values ​​for the clutch actuation variable, filling equalization of the clutch is performed (52, 62).

7. The method according to any one of the preceding claims, characterized in that The clutch is actuated a first time starting from the weakly actuated clutch using the first value for the clutch actuation variable, and the clutch is actuated a second time starting from the stronger actuation clutch using the first value for the clutch actuation variable.

8. The method according to any one of the preceding claims, characterized in that The method comprises the steps of detecting a further value of a second operating variable of the motor (14) when the clutch is not actuated and determining clutch characteristic data as a function of the detected further value of the second operating variable.

9. The method according to any one of the preceding claims, characterized in that The method has the step of changing the clutch control as a function of the determined clutch characteristic data.

10. The method according to any one of the preceding claims, characterized in that The clutch is monitored using the calibration method.

11. The method according to any one of the preceding claims, characterized in that The clutch characteristic data includes at least one of the following data: - the relationship between the clutch operating amount and the torque that can be transmitted through the clutch; - Friction value; - Clutch hysteresis; and - Clutch wear characteristic values.

12. The method according to any one of the preceding claims, characterized in that The method further comprises the steps of detecting a clutch temperature and determining clutch characteristic data as a function of the detected clutch temperature.

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