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US 5,934,232 AGranted
Engine valve lift mechanism
AssigneeGeneral Motors Corporation
InventorsCynthia Ann Greene, Mark James Spath, Michael James Fox
Life of this patent
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AssigneeGeneral Motors Corporation
InventorsCynthia Ann Greene, Mark James Spath, Michael James Fox
Estimating the term…
Valve lift mechanism for an engine includes a two step variable valve lifter having roller followers for engaging multiple cams on an associated camshaft of the engine and an anti-rotation guide mounted in the engine externally of a cylindrical bore receiving the lifter. The guide engages an axial guide recess in the lifter body without requiring a corresponding recess in the bore. The lifter also has a saddle in a central low lift cam follower engagable by lock pins in an annular body of an associated high lift cam follower to lock the followers together for high valve lift operation. The saddle is disposed axially between a follower roller and a high pressure chamber of a hydraulic lash adjuster of the low lift cam follower so that lock pin loads are transmitted as compressive forces through the low lift follower. The high lift follower rollers are received in pockets having sides that are crowned by shallow convex curvatures defining axially extending ridges which limit axial motion of the rollers so that the rubbing surface and associated friction are limited. Various additional specific features are disclosed. Application of the features to other valve lifters and cam followers is anticipated.
Valve lift mechanism for an engine, said mechanism including support means, a camshaft carried by the support means and having a pair of spaced cams, a valve lifter including a cam follower having a cylindrical body with first and second annular ends and an outer cylinder surface reciprocably carried in a cylindrical bore of the support means, the first annular end including a pair of laterally spaced first cam engaging portions engaging the cams, and guide means for limiting rotation of the body around an axis of reciprocation, the guide means characterized by:
An engine valve lifter including a cylindrical body having first and second ends, said first end including cam engaging means and said lifter including valve connecting means adjacent said second end of the body, said first end defining a pair of spaced opposite sides, said cam engaging means including a roller received between said opposite sides and rotatable on an axle pin carried in said opposite sides, lateral motion of the roller being limited by engagement with said sides, characterized in that:
A roller variable hydraulic valve lifter for an engine, said lifter including coaxial high and low lift cam followers selectively lockable for reciprocation together along a common axis, said high lift follower including a cylindrical body with inner and outer cylinder surfaces and a first annular end carrying a pair of laterally spaced high lift cam engaging rollers, said low lift follower including a hollow piston with at least one closed end, a second end and a cylindrical outer wall reciprocably engaging the inner surface of said body, the closed end carrying a low lift cam engaging roller generally between said pair of high lift cam engaging rollers, hydraulic lash adjusting means in the low lift cam follower and including a plunger reciprocable in said hollow piston and carrying a check valve, the plunger defining a high pressure chamber between the check valve and the closed end of the piston and an inner reservoir extending from the check valve toward the second end of the piston, and locking means including hydraulic locking pins reciprocably mounted in said body of the high lift follower for selectively locking the followers together for coincident reciprocating motion, said locking means further characterized by:
Dependencies are inferred from the claim text.