Valve Gear Energy Consumption: Effect of Design and Operation Parameters

Valve gear fixture tests have been conducted to determine the torque required to operate the valve gear of various four cylinder engines. The magnitude of these drive torques was used as an indication of the energy consumption level for a particular test. Engine speed, oil temperature and valve spring load were test variables subsequently determined to have a major effect on valve gear energy consumption. Cam journal and oil seal losses were also determined to contribute significantly to the total losses within the valve gear. The effects of oil pressure in hydraulic valve gear and different lash values in mechanical valve gear were also evaluated. Although the direct acting valve gear resulted in the lowest losses of those types tested, the different design objectives for each type did not permit a quantitative ranking of their relative efficiencies. Test results have shown that the energy consumption within a valve gear is a complex interplay of many factors including an implied dependence on the presence and quality of the oil film at the cam/follower interface.