Friction Clutch Engagement Point Adaptation via Speed Gradient
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Solution Overview
Problem
Existing methods for adjusting the point of engagement of a friction clutch in automated transmissions are not rapid enough and can be interrupted by gearshifts or vehicle operation, and they often require complex calculations involving torque transmission.
Innovation Solution
A method that adjusts the point of engagement by setting the clutch actuator and shift actuator to transitional values simultaneously, using a speed gradient value determined during a transitional state, allowing for rapid adjustment without interrupting gearshifts and allowing the adjustment to occur in inactive transmission branches while the vehicle is in operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If existing methods for adjusting the point of engagement are used, then the adjustment can be performed, but the process is not rapid enough and can be interrupted by gearshifts or vehicle operation
Solution Approach 1:
The method performs preliminary identification of the point of engagement during vehicle operation by utilizing transient states that naturally occur during gear shifts. The control device identifies the point of engagement by detecting when the input shaft speed matches the output shaft speed during a gear shift transient, rather than waiting for a separate adjustment process. This preliminary identification during normal operation eliminates the need for time-consuming separate adjustment procedures and prevents interruptions.
2Device complexity
If existing adjustment methods are used, then the point of engagement can be adjusted, but complex calculations involving torque transmission are required
Solution Approach 1:
The method replaces complex torque transmission calculations with a direct speed comparison measurement. Instead of calculating torque based on multiple parameters and mathematical models, the control device simply compares the measured input shaft speed with the measured output shaft speed during a gear shift transient. When the speeds match, the point of engagement is identified. This substitution of mechanical calculation with direct speed measurement significantly reduces computational complexity while maintaining high precision.
3Productivity
If adjustment is performed during vehicle operation, then gear shifts are not delayed, but the adjustment process may be interrupted
Solution Approach 1:
The method continuously monitors shaft speeds during normal vehicle operation and gear shifts, utilizing every available transient state for identification. Rather than performing discrete adjustment cycles that can be interrupted, the control device continuously captures speed data and identifies the point of engagement whenever the conditions are met during natural gear shift transients. This continuous approach ensures that the adjustment process is never truly interrupted while maintaining gear shift efficiency.
4Reliability
If multiple operating points are measured for reliable adaptation, then the adaptation is more reliable, but the process takes more time
Solution Approach 1:
The method utilizes the natural gear shift transients that occur during normal vehicle operation to automatically identify the point of engagement. The vehicle's own gear shifting actions serve the dual purpose of both transmission operation and clutch characteristic identification. The control device captures data during these self-occurring transients and performs the identification without requiring separate test procedures or multiple deliberate operating point measurements, thereby eliminating time loss while maintaining reliability through continuous monitoring.
Data Source
AI summary
A method for adjusting the point of engagement of a friction clutch of a step-variable transmission for a motor vehicle, in particular a friction clutch of a dual clutch transmission. The friction clutch is controllably actuated by means of a clutch actuator and at least one synchronizer shifting clutch is controllably actuated by means of a shift actuator for the engagement and disengagement of a gear ratio of the spur-gear transmission. A set-point of the clutch actuator for the point of engagement of the friction clutch is adjusted as a function of a speed gradient value, which ensues from a transitional state with the friction clutch actuated and the shifting clutch actuated, once the shifting clutch is opened. The transitional state is established by setting the clutch actuator and the shift actuator to a respective transitional value substantially at the same time or, at least in sections, in parallel.