Camshaft phaser having dual counter-threaded helical mechanisms

摘要

A mechanically-actuated camshaft phaser for varying the phase of a camshaft in an internal combustion engine. The phaser comprises two colinear helical mechanisms having opposite-handed helices engaging a common nut for common rotation. One helical mechanism is operatively attached to a sprocket or pulley in time with an engine crankshaft. The other helical mechanism is operatively attached to an engine camshaft. A motive system drives the nut axially of itself along the helical mechanisms, causing a phase shift between the mechanisms and hence between the crankshaft and the camshaft. The preferred helical mechanisms are ball screws, and the preferred motive system is a worm gear driven by a worm on the shaft of an electric motor.