Energy efficency improvement of timing chain drives

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Timing assemblies of internal combustion engines are more often designed as chain drive. Compared to tooth belt drives, timing chain drives have many advantages, such as the lower need of space and lower costs for maintenance and acquisition. The only disadvantage of timing chain drives is the lower energy efficiency. The chain of a timing chain drive hast to be almost completely guided and tensioned to ensure operational safety. The transfer of tensioning force is accomplished via a hydraulic tensioning system, which transmits the force via sliding contacts on the chain. The lower energy efficiency is due to the chain-rail contacts. In the first period (DFG SA 898/10-1) approaches were investigated, with which a power loss reduction of timing chain drives is possible. Approaches as the need-based adjustment of chain tensioning force at each operating point, the optimization of the lubricant supply and the optimization of the rail surface were investigated. In doing so, some positive approaches were found. The tests were conducted at steady-state operating points on a test stand, including the oscillations of the valve train. In the next step, the oscillations of the crankshaft and pistons, and the rotation irregularities caused by the gas forces will be taken into account. In addition, transient operating conditions are considered. Furthermore, the positive approaches of targeted lubrication will be further developed and investigations on textured link plates will be conducted.