Device for adjusting the relative rotational background of camshafts
AssigneeH.c.f. Porsche Aktiengesellschaft
InventorsWolfgang Stephan, Alfred Trzmiel
Life of this patent
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Abstract
A combustion engine valve control camshaft adjusting mechanism includes hydraulically actuated piston members to control the relative rotational position of a pair of camshafts. A locking detent is biased by a spring toward a locking position preventing the adjusting movement of the piston members. Hydraulic pressure is supplied to the detent in a direction opposite the spring to release the locking detent and permit the adjusting mechanism to operate after a predetermined engine warmup phase of up to a few seconds.
Claims17
Device for tensioning and adjusting the relative rotational positions of camshafts with respect to one another that are rotatably mounted in an engine for actuating valves, wherein said device cooperates with a locking device that secures the positioning mechanism of a hydraulic piston of the device before starting or up to a point shortly after the starting of the engine,
- wherein the device for tensioning and adjusting is designed as a chain drive comprising a chain by which one camshaft of the engine drives a second camshaft, so that by adjusting the chain using a tensioning device that operates transversely to the chain, the relative rotational positions of the camshafts with respect to one another are changed, said tensioning device being displaced transversely to the chain for adjusting said chain, in such fashion that the slack side of the chain is lengthened and the tight side is shortened or the slack side is shortened and the tight side is lengthened, with this tensioning device being operated hydraulically and comprising a hollow outer hydraulic piston, a likewise hollow inner hydraulic piston guided lengthwise therein, and a coiled compression spring tensioned in the cavity between the two hydraulic pistons,
- wherein the locking device cooperates with the outer hydraulic piston and can be operated hydraulically and mechanically, and
- wherein the locking device comprises a locking piston that is located radially with respect to the outer hydraulic piston and cooperates with a recess designed as a receptacle in the outer hydraulic piston.
A camshaft adjusting mechanism for adjusting relative rotational positions of first and second engine valve control camshafts, comprising:
- a movable hydraulic adjusting piston operable to change the relative rotation position of the first and second camshafts as a function of the adjusting position of the adjusting piston,
- a locking member operable to selectively lock the adjusting position against adjusting movement, and
- a locking control system operable to control the locking member as a function of engine operating conditions such that the locking member locks the adjusting piston against adjusting movement before engine startup and for a predetermined period of time after engine startup,
- wherein said locking member is a locking piston member engageable radially in a recess of the adjusting piston, and
- wherein said locking control system is a locking spring biasing the locking piston member toward a locking position.
Dependencies are inferred from the claim text.