Phase changing device between a shaft and its driving pulley

摘要

An adjustable valve timing for an IC engine has the camshaft drive gear linked to the camshaft by a phase adjustment comprising fixed and movable vanes and by altering the relative hydraulic pressure in the chambers between the fixed and movable vanes. To prevent grit from being dragged under the movable vanes the inside wall of the outer housing is cut with a pattern of grooves (25). The grooves have sufficient depth and are spaced sufficiently close to collect grit. The movable vanes cover at least two grooves at any time.