Patent ID: 7546820
Filing Date: 2009-06-16
Classification: F02B,F02D,F16C,F16J

Abstract:
1. A variable compression ratio piston and rod assembly for an internal combustion engine, said assembly comprising: a piston having a pin bore centered along a first axis; a piston pin disposed in said pin bore; a connecting rod having a lower crank end and an upper piston end, said upper piston end including a rod bore centered along a second axis that is offset from and parallel to said first axis of said pin bore; an eccentric bushing pivotally interconnecting said piston pin and said rod bore, said eccentric bushing including a bore along said first axis that receives said piston pin and an eccentric outer journaled portion carried in said rod bore, said eccentric bushing being rotatable so as to effect a spatial displacement between said piston and said connecting rod to effectively alter the compression ratio created by said assembly when operatively disposed in an internal combustion engine; an actuator selectively energizable for producing an actuation impulse; a latch responsive to said actuation impulse for movement between a latched position in which said eccentric bushing is fixed in one of at least two rotated positions, and an unlatched position in which said eccentric bushing is freely moveable relative to said connecting rod; and a lost motion coupling operatively disposed between said actuator and said latch, said lost motion coupling functionally decoupling said actuator from said latch in response to a dominant shearing load between said eccentric bushing and said connecting rod trapping said latch in said latched position and for automatically re-coupling said actuator to said latch when the dominant shearing load falls below a predetermined limit, whereby said lost motion coupling enables said actuator to produce said actuation impulse while said latch remains trapped in said latched position without damaging said latch and also automatically moving said latch to said unlatched position at a later convenient time.