Abstract: A crankpin on the crankshaft of a variable compression engine carries an eccentric bushing which is positionable about the crankpin axis to determine the length of piston stroke. To counteract the relocation of the bushing center of gravity counterweights are rotatably housed in a counterbalance of the crankshaft. Partial rotation of each counterweight shifts their centers of gravity with respect to the crankshaft axis of rotation to achieve crankshaft balancing. For positioning of the counterweights coincident with shifting of the eccentric bushing the same are shown coupled with gears. Positioning of the eccentric bushing to change piston stroke of the engine is by a motor responsive to a microprocessor and engine performance criteria.

Abstract: A crankshaft carried crankpin carries an eccentric interposed between the crankpin and the slider of a yoke type engine. The eccentric carries a gear to permit rotatable adjustment to be imparted to the eccentric about the crankpin axis. Positioning of the eccentric includes the use of a gear train. A gear set in the gear train has displaceable gears carried by a carrier responsive to engine control means. The movable gear set serves to accelerate or decelerate the rotational speed of a pair of shaft mounted driven gears to momentarily alter their rotational speed so as to in turn rotate the eccentric mounted gear to reorientate the eccentric to the crankpin. Such relocating of the eccentric serves to alter the piston stroke between high and low compression ranges.

Abstract: A yoke type engine wherein the orbital path of the slider is alterable to effect piston stroke and compression ratio changes. A crank component has a crankpin which carries and positions the slider. A boss of the crank component is carried by a control shaft in an offset manner. Timing gears normally drive the control shaft in synchronization with the crankshaft to maintain a constant stroke and compression ratio. Relocation of certain timing gears by an actuator causes the control shaft to rotationally advance or retard to reposition the crank component carried thereby to in turn alter the orbital path of the coaxial crankpin and slider relative to a crankshaft axis. Accordingly, high and low compression orbits for the slider may be effected to best suit engine loads. A variable length throw couples the slider to the crankshaft. The orbital path of the slider provides increased crankshaft leverage over conventional engine arrangements.