Balancer for 90 degree V6 engines and the like

Claim 1

A 90° V-6 internal combustion engine having cylinder banks with pistons connected by connecting rods to dual offset pins of three longitudinally spaced throws of a rotatable crankshaft, the pins of each throw being offset 30° and the engine being timed to provide equal firing intervals between cylinders, the piston-crank mechanism causing a mechanical imbalance comprising an eccentric primary rotating unbalance couple turning in the direction of crankshaft rotation and an eccentric secondary rotating unbalance couple turning opposite the direction of crankshaft rotation, both unbalance couples having smaller moment axes lying in a first longitudinal plane spaced equally between the cylinder banks and having larger moment axes lying in a second longitudinal plane normal to said first plane, and the improvement comprising balancing means for the engine including the combination of balance weights on the crankshaft and separate balancer means attached to the engine and rotatably driven at crankshaft speed in opposite rotational direction from the crankshaft, said crankshaft balance weights being sized and positioned to offset a portion of the primary rotating unbalance couple equal in magnitude to the smaller moment of the first plane plus one half the difference between the larger and smaller primary unbalance couple moments, and said separate balancer means comprising a pair of Oldham coupler balancers, each having a pair of end members connected by a coupler member and all rotatable together on spaced parallel axes at identical driven speeds whereby each coupler member orbits in a path through the axes of its connected end members at twice the driven speed, said Oldham coupler balancers being spaced longitudinally of the engine with said rotational axes parallel to the crankshaft and having eccentric balance weights rotatable with at least one of the end members of each balancer, said end member balance weights being selected and positioned to offset the remaining primary unbalance couple in the second plane and the excessive balancing couple in the first plane to provide complete balance of primary couples, and said coupler members having appropriate mass and following orbital paths selected to offset a portion of the engine secondary rotating unbalance couple.