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US 6,536,393 B2Granted
Mechanical compression and vacuum release
AssigneeTecumseh Products Company
InventorsKeith A. Novak, James R. Dietz, Michael A. Mahy
Life of this patent
Estimating the term…
Abstract
An internal combustion engine having a vacuum release mechanism that includes a centrifugally actuated member movably attached to the camshaft and having a vacuum release cam extending therefrom. The vacuum release cam is in lifting engagement with the exhaust valve assembly at crankshaft cranking speeds during a portion of the power stroke to relieve vacuum forces opposing motion of the piston. The vacuum release cam centrifugally pivots out of engagement with the exhaust valve assembly in response to the crankshaft attaining running speeds.
Claims21
An internal combustion engine, comprising:
- a cylinder block including a cylinder therein and having a piston reciprocally disposed within said cylinder, said piston operably engaged with a crankshaft;
- a camshaft in timed driven relationship with said crankshaft;
- at least one intake valve assembly reciprocally driven by said camshaft;
- at least one exhaust valve assembly reciprocally driven by said camshaft;
- a vacuum release mechanism, comprising:
- a vacuum release member attached to said camshaft and centrifugally moveable between first and second positions, said vacuum release member including a vacuum release cam extending therefrom, said vacuum release cam in lifting engagement with one of said valve assemblies in said first position during at least a portion of a power stroke of said piston to relieve vacuum forces opposing said power stroke, said vacuum release cam disposed out of engagement with said one of said valve assemblies in said second position.
3 more elements
An internal combustion engine, comprising:
- a cylinder block including a cylinder therein and having a piston reciprocally disposed within said cylinder, said piston operably engaged with a crankshaft;
- a camshaft in timed driven relationship with said crankshaft;
- at least one intake valve assembly reciprocally driven by said camshaft;
- at least one exhaust valve assembly reciprocally driven by said camshaft;
- and
- a compression and vacuum release mechanism, comprising:
- a compression and vacuum release member attached to said camshaft and centrifugally moveable between first and second positions, said compression and vacuum release member including a compression release cam and a vacuum release cam extending therefrom, said compression and vacuum release cams respectively in lifting engagement with one of said valve assemblies in said first position during a portion of a compression and a portion of a power stroke of said piston to relieve compression and vacuum forces respectively opposing said compression and said power strokes, said compression and vacuum release cams disposed out of engagement with said one of said valve assemblies in said second position.
4 more elements
An internal combustion engine, comprising:
- a cylinder block including a cylinder therein and having a piston reciprocally disposed within said cylinder, said piston operably engaged with a crankshaft;
- a camshaft in timed driven relationship with said crankshaft;
- at least one intake valve assembly reciprocally driven by said camshaft;
- at least one exhaust valve assembly reciprocally driven by said camshaft;
- and
- a compression and vacuum release mechanism, comprising:
- a centrifugally actuated common yoke member moveably attached to said camshaft between a first position corresponding to a cranking speed of said engine and a second position corresponding to a running speed of said engine;
- a compression release cam extending from said yoke member and in lifting engagement with one of said valve assemblies in said second position during a portion of a compression stroke of said piston to relieve compressive forces opposing said compression stroke;
- and
- a vacuum release cam extending from said yoke member and in lifting engagement with said one of said valve assemblies in said first position during a portion of a power stroke of said piston to relieve vacuum forces opposing said power stroke;
- said compression and vacuum release cams disposed out of lifting engagement with said one of said valve assemblies in said second position.
8 more elements
Dependencies are inferred from the claim text.