Frictionless rocking joint

A piston-and-crank assembly, comprising:

• a crankshaft having an eccentric journal;
• a reciprocating element coupled to a component having a non-circular pin;
• and
• a connecting rod having a big end coupled to the eccentric journal of the crankshaft and a small end coupled to the pin, wherein the connecting rod has a primary rod bearing surface that comprises a portion of a cylinder having a radius of curvature substantially equal to a distance between the primary rod bearing surface and a central axis of the eccentric journal.

An internal combustion engine, comprising:

• a cylinder liner;
• a pair of pistons disposed in the cylinder liner in an opposed arrangement with tops of the pistons facing each other;
• a pushrod coupled to each piston at a first end of the pushrod;
• guide surfaces provided for each pullrod with a second end of the pushrod riding on the guide surfaces and the guide surfaces are substantially parallel with an axis of the cylinder;
• a pullrod coupled to each of the pushrods with a second end of the pushrod coupled to a first end of the pullrod;
• a crankshaft having two main bearing journals, a first eccentric journal, and a second eccentric journal wherein:
• a second end of a first of the pullrods is coupled to the first eccentric journal;
• and a second end of a second of the pullrods is coupled to the second eccentric journal;
• a joint between the second end of the pushrod and the first end of the pullrod is a rocking joint with a concavely-curved bearing surface on the pullrod mating with a convexly-curved bearing surface of a non-cylindrical pin coupled to the second end of the pushrod;
• a radius of curvature of the concavely-curved bearing surface on the pullrod is substantially equal to the distance between the bearing surface and a central axis of the off-center eccentric journal;
• the convexly-curved surface has a radius of curvature less than the radius of curvature of the concavely-curved surface;
• and
• the convexly-curved surface rides on the concavely-curved surface in a rocking fashion substantially avoiding sliding motion between the two surfaces.

A piston-and-crank assembly, comprising:

• a crankshaft having an eccentric journal;
• a reciprocating element coupled to a component having a non-circular pin;
• a connecting rod having a big end coupled to the eccentric journal of the crankshaft and a small end coupled to the non-circular pin of the component wherein the connecting rod has a primary rod bearing surface that comprises a portion of a cylinder having a radius of curvature substantially equal to a distance between the primary rod bearing surface and a central axis of the eccentric journal;
• a cylinder liner having a piston disposed therein;
• and
• a bridge coupled between the piston and the reciprocating element.