Continuously variable transmissions (CVTs) are applied in an increasing number of vehicles. Large ratio coverage allows for reduced engine speeds, which adds to both highway driving comfort and reduced fuel consumption. It becomes increasingly important to further improve the performance in terms of efficiency, robustness and torque capacity of the CVT. This paper describes the possibilitities of improving the CVT by minimising variator clamping forces. This is accomplished by using slip control technology. This technique allows for the best possible transmission efficiency, combined with improved robustness for slip damage. This paper first describes the relation between variator slip and functional transmission properties. The conditions for otimum performance regarding efficiency and robustness are identified. This leads to the development of a variator slip controller. The remaining sections describe experimental results on two test rigs. Presentation of slip control in a production vehicle with only minor modifications, proves the viability of this technology also for industrial applications. Control problems that were identified during test driving, could be attributed to shortcomings in control logic, due to insufficient modelling detail. Although slip control showed good functionality in a production vehicle, additional hardware modifications for good performance under more demanding conditions may be necessary. Future research must focus on: reduction of clamping forces under low load conditions, while maintainig a fast hydraulic response; improvement of actuator dynamics; improved slip measurement technology, included shift dynamics in slip dynamics modelling.
Performance optimisation of the push-belt CVT by variator slip control
Leistungsoptimierung von Schubriemen-CVT-Getrieben mit Hilfe der Variator-Schlupfregelung
International Journal of Vehicle Design ; 39 , 3 ; 232-256
2005
25 Seiten, 20 Bilder, 2 Tabellen, 9 Quellen
Article (Journal)
English
Performance optimisation of the push-belt CVT by variator slip control
Online Contents | 2005
|Performance optimisation of the push-belt CVT by variator slip control
Automotive engineering | 2005
|Determination of variator robustness under macro slip conditions for a push belt CVT
Automotive engineering | 2004
|Determination of Variator Robustness Under Macro Slip Conditions for a Push Belt CVT
British Library Conference Proceedings | 2004
|Determination of Variator Robustness Under Macro Slip Conditions for a Push Belt CVT
SAE Technical Papers | 2004
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