Reciprocating machines with both primary and secondary counter rotating

Abstract

This invention is best suited for counterbalancing a single reciprocating (recip) member (such as a piston). A con rod interconnects a rotary crankshaft to a recip member. Two main counterweights are attached to the crankshaft and rotate therewith. Two coaxial contraweights rotate in the opposite direction from the crankshaft and at the same RPM as the crankshaft. The two main counterweights plus the two contraweights combine forces so as to balance the primary recip inertia forces. Two secondary weights are mounted on two parallel countershafts and they rotate at twice crankshaft RPM and in opposite directions from each other so as to balance the secondary recip inertia forces. A positive toothed driving means (such as gearing) is used to drive the two said countershafts from the crankshaft. The same gearing plus the two said countershafts are also used to assist in driving the two said contraweights so as to minimize the total number of shafts, bearings, and gears. So as to further cut down on the number of gears and cost, two of the drive gears are extra wide; they mesh in two separate planes; and thus perform a double function. In one species, the said two contraweights are attached to a single hollow shaft which surrounds the main shaft of the crankshaft. The said secondary weights have a large L/D so as to reduce their flywheel effect for a given static moment.