Slip behavior in pulley groove up to sliding slip at steady state and power transmitting efficiency on metal V-belt type cvt

Abstract

This paper investigated the influence of pulley tilting on slip ratio (s) of the commercially available continuously variable transmissions (CVTs). Two types of pulleys (tiltable pulley and untiltable pulley) were prepared to investigate the influence of the tilt of pulley on the slip properties. The tilt of the driving pulley was prevented for simple comparisons when untiltable driving pulley was applied, while tiltable pulleys were conventionally used. The maximum transmitting efficiency (η) and the maximum transmitting torque were increased when untiltable pulleys were used, while slip ratio (s) was decreased. The radial displacement of contacting point due to the tilt of pulley was much affected to the penetration of the belt about max 70 times compared with that by rolling, when pulley surface was tilted. The remarkable penetration was prevented by applying untiltable pulley. In current type of CVT, practical CVT unit for commercial uses was usually driven with the slip in circumferential direction due to the tilt of pulley accompanying with radial displacement of the belt. This paper found that about 33% of slip was counted due to the tilt of pulley in observed total slip between driving and driven pulley by the specific reason where the driving pulley should be tiltable for the motion of the shift in axial direction on the shaft. The observed slip was dominantly caused by the penetration of the belt when the driven pulley was tilted.

Keywords

• metal v-belt
• cvt
• untiltable pulley
• tilting angle
• radial displacement