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Apart from performance, comfort, cost and fun to drive, the reduction of fuel consumption has become a primary driver in the world market of the automotive industry. As continuously variable transmissions based on the pushbelt principle can be operated in an optimal state at any time, they are very suitable to meet the mentioned requirements. However, the power transmission in the system is very complicated. Both detailed measurements and simulations are necessary to understand and to optimize the physical mechanisms, power density and shift characteristics. The current paper presents a spatial simulation model for transient analysis at different levels of detail. An initial model based on non-smooth multi-body theory is outlined. It consists of two rigid pulleys each with one tilting loose sheave. The pushbelt comprises two ring packages based on the co-rotational approach.

Chain drives are used in powertrains for the kinematic coupling of the cam shaft, the ancillary units and the balancing shafts with the crank shaft. Advantages of chain drives are their high load carrying capacity along with increased durability whilst simultaneously being maintenance-free. A crucial issue in the drive is the optimization in regard of friction, further improving efficiency, reducing exhaust emission and abrasive wear. Modeling friction in drive systems requires precise description of the whole system dynamics. High-frequency oscillations occurring in the chain strands cause numerical problems in the friction computation. As a remedy, regularized friction curves are often used, being however not able to correctly determine all friction configurations and requiring a tradeoff between accuracy and computational efficiency.