In timing chain drives, the chain joint, consisting of bush and pin, is the most critical component regarding wear and energy efficiency. Due to the drive design layout, there are relative motions inside the chain joints. These processes can be found at the in- and outlet of the chain joint on the sprockets, but also induced by vibrations of the slack strand. The contact loads and the relative motions cause wear of bush and pin, so the joint clearance and the chain length increase. The contact loads and relative motions lead to friction losses that influence the energy efficiency of the entire chain [1]. Therefore, an optimization of the wear characteristics is necessary to realize an improvement of the efficiency of the entire combustion engine. By using various materials for bush and pin and also different surface treatments of both components, the tribological system was continuously improved. Surface texturing of the chain components of the joint contact is another possible approach to improve efficiency. Test rigs which allow investigations on entire chains are not suitable for systematic tests of chain components with modified surfaces because of a considerable amount of modified parts needed. To overcome this drawback, a rig for investigations on a single chain joint, called chain joint tribometer, was built at the Institute of Machine Elements, Gears & Transmissions (MEGT). The following chapters present the chain joint tribometer and demonstrate initial results regarding friction and wear.
展开▼
