Development of the micro-texture to the CVT pulley's sheave surface for generated high friction coefficient

摘要

The friction coefficient (μ) between the pulley's sheave surface and the belt elements of a steel belt in continuously variable transmission (CVT) is increased by 20% from the current level. It would be increased the automobile fuel efficiency about 2% by generating boundary lubrication films with a combination of the surface micro-texture and the molecular structure of lubricant additives. In this study, the relationship between the micro-textures of various process surfaces such as hard-turning, shot-peening, grinding, Electrolytic In-process Dressing (ELID grinding), and lapping surfaces, and the friction coefficient of the pulley's sheave surface was studied. As a result, under this test, as the micro-texture by using a hard-turning and lapping process was found to be better for the generated high friction coefficient (μ) between the pulley's sheave surface and the belt elements. The significant influence of the friction coefficient (μ) of pulley's sheave surface and the belt elements equaled the arithmetic mean deviation of the profile (Ra) and the mean width of the profile (RSm). RSm is especially important. As Ra and the RSm decreased, the real contact areas and boundary lubrication films on the pulley's sheave surface and the belt elements increased. Therefore, the friction coefficients (μ) between the pulley's sheave surface and the belt elements increased.