| 摘要 |
A compact cam phaser has a flexible spline deformed into a nonround shape and engaging a mating ring gear or circular member at angularly spaced locations for transferring camshaft drive torque between them. The spline has projecting lobes with teeth or friction surfaces which engage like surfaces formed on the mating gear or member. The spline and ring gear have a differential length or number of teeth. The phaser includes a plurality of angularly spaced radial piezo actuators, which expand and contract to cause the projecting lobes (but not the flexible spline itself) to travel around the circular ring gear in rotating waves. Thus, each point of the flexible spline is moved sequentially into and out of contact with the ring gear as the contact points (lobes) rotate in waves. Since the number of spline teeth differs from the ring gear, one revolution of the waves causes the spline to move relative to the ring gear a number of teeth equal to the differential. The phase angle of the flexible spline relative to the ring gear, and the camshaft relative to the crankshaft, is thus changed by an amount proportional to the revolutions of the waves. The piezo actuators are controlled in known manner by the application and withdrawal of electric voltage which causes the actuators to alternately expand and contract, driving the wave rotation of the spline lobes rapidly to change the phase angle. Various embodiments are disclosed.
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