Cardanic Rocker Arms-A Method to Reduce Valve Train Friction 880569
Cardanic rocker arms provide a rolling action at the rocker-arm pivot. This simple design concept is able to reduce friction at this interface by replacing sliding friction with rolling friction. Substantial reductions in valve train friction result, and the measurable improvement in vehicle fuel economy is 1 to 2 percent. To ensure rolling motion over the range of action, it is necessary to include a restraining element in the design. Several restraining elements have been investigated and the final design includes a simple alignment system integrated into the pivot. Numerous tests have demonstrated that a configuration consisting of a stamped rocker arm and a powdered metal pivot meets passenger car engine durability requirements.