Abstract
Research and /or Engineering Questions/Objective:
Present paper focuses on lubricated disk clutches submitted to torque oscillations concerning mainly the frictions disks. Geometrical deviations of these disks can lead to contact pressure deviations and consequently to torque oscillations. Present work aims at reducing these resulting vibrations that can lead to judder vibration if their frequency reaches the first range of eigenfrequency of a powertrain.
Methodology:
Within the scope of study, the subsystem “disk pack” of a wet clutch system is considered. First, its present design can be linked with its function by means of the Contact and Channel Approach (C&C²-A). This so called “function model” enables it to identify which function is responsible of the judder vibrations and so which part of the design needs to be set under focus. Analysis delivered a direct link between a “design property A” of the disks and vibrations observed in the system. Different hypotheses were formulated to override this dynamic phenomenon. One solution to compensate deviations from the ideal disk shape would be to decrease the deviation from the ideal shape representing the deviation of the “design property A”. This first possibility would lead to an increase of manufacturing costs. Another way would be to change the properties of other functional elements leading to an improvement in the overall functional quality. Last solution chosen in the present work consists in changing the “design property B” of the disks. This can compensate the juddering and a robust functional performance can be realized. The functional relation is examined and verified on the basis of experiments.
Results:
The experimental studies of the torque oscillations observed in the disk pack show a significant functional relation between the “design property A” and a periodic excitation of the transmitting torque. Furthermore, it can be shown that an additional change of the “design property B” causes a significant vibration reduction. To conclude, changing the “design property B” improves its functional performance as a more constant torque transmission can be transmitted by changing the “design property A”.
Limitations of this study:
Both the analysis and the synthesis are performed on a specific subsystem of a wet clutch and thereby two design parameters are considered. A transfer to other clutch systems cannot be shown within the scope of study.
What does the paper offer that is new in the field in comparison to other works of the author:
Contact and Chanel approach has been applied to analyse a technical system in order to improve the functional quality of the system. This is achieved and verified in experimental studies. Therefore the “design property B” has a significant influence on torque oscillation of a wet clutch system.
Conclusion:
A systems analysis and synthesis of the subsystem “disk pack” is carried out by using the C&C² approach. By changing the “design property B”, the deviations from the ideal “design property A” can be compensated and a constant torque transmission can be realized.
KEYWORDS – wet clutch, torque oscillation, judder excitation, forced excitation, C&C²-A