In this paper a numerical analysis to evaluate the influence of the temperature on the static load-deflection curve of a cushion spring in an automotive dry-clutch system was proposed. The analysis emphasizes that the temperature influences the cushion spring characteristic in two ways. In fact, by increasing the temperature, the material stiffness decreases and this is highlighted by a reduction in the curve slope. Conversely, the thermal load induces a pre-stress effect and this results in a nonzero reaction force before compression starts. The comparison of the load-deflection curves calculated at different temperatures proves that the superposition of the two effects generates for the considered cushion spring an intersection of all curves at a particular point. Since the cushion spring load-deflection curve accounts for the main contribution to the clutch transmissibility characteristic, i.e. the torque versus throw-out bearing position curve, the influence of the temperature on the cushion spring is an important issue in order to design properly the control algorithms of the TCU (transmission control unit) assisting the automated gearbox. In fact, the TCU control strategies normally consider degradation in the torque transmission characteristic as a consequence of the temperature rise, with an overall modification due to many phenomena (the frictional behaviour of the clutch facings, backlashes, thermal distortion, etc). The outcome of this analysis could become a key element for designers of automated clutches and control engineers in recasting the cushion spring concept in order to overcome the poor engagement performance exhibited by AMTs (automated manual transmission) after repetitive gear shifting.
Modelling the cushion spring characteristic to enhance the automated dry-clutch performance: The temperature effect
Modellierung der Balgfederkennlinie zur Verbesserung des Verhaltens von automatiserten Trockenkupplungen: Temperatureinfluss
2012
11 Seiten, 17 Bilder, 1 Tabelle, 17 Quellen
Aufsatz (Zeitschrift)
Englisch
Anwendung im Fahrzeugbau , Federkennlinie , Federungsverhalten , Trockenkupplung , Temperatureinfluss , Temperaturverhalten , Federbalg , numerische Analyse , statische Last , Steifigkeit , Federvorspannung , Steuerungs- und Regelungsalgorithmus , automatisches Getriebe , Getriebeschaltverhalten , Regelungsstrategie , theoretisches Modell , Pkw (Personenkraftwagen)
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