Crankshaft phasing mechanism

In a VCR engine having two crankshafts which rotate about parallel axes, one or more pairs of pistons with one piston in each pair linked to one of the crankshafts and the other piston in each pair linked to the other crankshaft, the pistons in each pair operating in interconnected cylinders, a phase adjuster mechanism including an axially movable adjuster member and two pairs of helical phasing gears, said member rotatable about an axis parallel to the axes of rotation of the crankshafts and supported by radial sliding bearings, each pair of said phasing gears consisting of a phasing gear fixedly mounted on a respective one of said crankshafts and a respective wider phasing gear operatively engaged therewith and fixedly mounted on the adjuster member, the respective helix angles and directions of helices of said phasing gears being arranged to alter the phase relation between the two crankshafts in response to axial displacement of the adjuster member, the combination comprising:

• an engine block;
• connecting rod means operatively associated with the crankshafts;
• each of said crankshafts together with the connecting rod means associated therewith sweeping a respective envelope during engine operation;
• each of said two phasing gears on said adjuster member bounded by a respective imaginary cylindrical surface whose axis coincides with and whose points are equidistant from the axis of rotation of said adjuster member, and whose diameter is equal to the outside diameter of said phasing gear bounded thereby and which extends axially along the length of said engine block without intersecting said envelopes.