| 摘要 |
A camshaft (126) has a vane (160) secured to an end thereof for non-oscillating rotation therewith. The vane has opposed lobes (160a/160b) which are received in opposed recesses (132a/132b) respectively, of a sprocket (132) which is oscillatingly journalled on the camshaft. The recesses have greater circumferential extent than the lobes to permit the vane and sprocket to oscillate with respect to one another, and thereby permit the camshaft to change in phase relative to a crankshaft whose phase relative to the sprocket is fixed by virtue of a timing belt drive extending therebetween. The camshaft experiences torque reversals as it rotates due to valve follower force on cam lobes attached to the camshaft, and such torque reversals are partly counteracted by a flywheel (144) fixedly attached to the camshaft. The camshaft phase is permitted to change in a given direction, either to advance or retard, by selectively blocking or permitting the flow of hydraulic fluid, preferably engine oil, from the recesses by controlling the position of a spool (200) within a valve body (192) of a control valve in response to a signal indicative of an engine operating condition from an engine control unit (208).
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