Split-cycle engine with dwell piston motion

An engine comprising:

• a crankshaft having a crank throw, the crankshaft rotating about a crankshaft axis;
• a compression piston slidably received within a compression cylinder and operatively connected to the crankshaft such that the compression piston reciprocates through an intake stroke and a compression stroke of a four stroke cycle during a single rotation of the crankshaft;
• an expansion piston slidably received within an expansion cylinder;
• a connecting rod pivotally connected to the expansion piston;
• a mechanical linkage rotationally connecting the crank throw to the connecting rod about a connecting rod/crank throw axis such that the expansion piston reciprocates through an expansion stroke and an exhaust stroke of the four stroke cycle during the same rotation of the crankshaft;
• and
• a non-circular path established by the mechanical linkage which the connecting rod/crank throw axis travels around the crankshaft axis, the distance between the connecting rod/crank throw axis and crankshaft axis at any point in the path defining an effective crank throw radius, the path including a first transition region beginning a predetermined number of degrees CA past top dead center, the first transition region transitioning from a first effective crank throw radius to a larger second effective crank throw radius through which the connecting rod/crank throw axis passes during at least a portion of a combustion event in the expansion cylinder.

An engine comprising:

• a crankshaft having a crank throw, the crank throw having a slot disposed therein, the crankshaft rotating about a crankshaft axis;
• a compression piston slidably received within a compression cylinder and operatively connected to the crankshaft such that the compression piston reciprocates through an intake stroke and a compression stroke of a four stroke cycle during a single rotation of the crankshaft;
• an expansion piston slidably received within an expansion cylinder;
• a connecting rod pivotally connected to the expansion piston;
• a crank pin rotationally connecting the crank throw to the connecting rod about a connecting rod/crank throw axis to allow the expansion piston to reciprocate through an expansion stroke and an exhaust stroke of the four stroke cycle during the same rotation of the crankshaft, the crank pin being slidably captured by the slot in the crank throw to allow radial movement of the crank pin relative to the crankshaft;
• and
• a template attached to a stationary portion of the engine, the template including a crank pin track into which the crank pin extends, the crank pin track movably capturing the crankpin such that the connecting rod/crank throw axis is guided through a path about the crankshaft axis.