Variable compression piston

In an internal combustion engine, an eccentric bearing (16) located between the connecting rod (14) and the piston pin (12) can be used to vary the compression ratio. In this invention the eccentric bearing is held in any position by a continuously variable hydraulic lock. The hydraulic lock is cont...

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Bibliographic Details
Main Author BEATTIE; JOHN F. E
Format Patent
LanguageEnglish
Published 23.05.1995
Edition6
Subjects
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Summary:In an internal combustion engine, an eccentric bearing (16) located between the connecting rod (14) and the piston pin (12) can be used to vary the compression ratio. In this invention the eccentric bearing is held in any position by a continuously variable hydraulic lock. The hydraulic lock is controlled by a valve assembly (30) which can fix or release the lock bar (18). When the lock bar is released the eccentric bearing can turn as a result of the upward or downward inertia and gas pressure forces on the piston (10). However, a check valve (34) in the valve assembly allows it to turn only in the direction set by the valve assembly until it reaches the new position and re-locks. Engine oil is provided at regulated pressures through oil passages in the connecting rod, eccentric bearing and piston pin to set the position of the valve assembly and to provide a supply for the hydraulic lock. The oil pressure is controlled by an engine-management computer and the position of the valve assembly is set by pressures which are varied within the normal operating limits of the engine. Advantages are continuous variability, little change to existing engine components, low parts count, relatively low addition to reciprocating weight, and no chance of failure due to partial engagement, impact or wear.
Bibliography:Application Number: US19930159208