Split four stroke engine

An engine comprising:

• a crankshaft, rotating about a crankshaft axis of the engine;
• a power piston slidably received within a first cylinder and operatively connected to the crankshaft such that the power piston reciprocates through a power stroke and an exhaust stroke of a four stroke cycle during a single rotation of the crankshaft;
• a compression piston slidably received within a second cylinder and operatively connected to the crankshaft such that the compression piston reciprocates through an intake stroke and a compression stroke of the same four stroke cycle during the same rotation of the crankshaft;
• and
• a gas passage interconnecting the first and second cylinders, the gas passage including an inlet valve and an outlet valve defining a pressure chamber therebetween, wherein the inlet valve and the outlet valve of the gas passage substantially maintain at least a predetermined firing condition gas pressure in the pressure chamber during the entire four stroke cycle.

An engine comprising:

• a crankshaft, rotating about a crankshaft axis of the engine;
• a power piston slidably received within a first cylinder and operatively connected to the crankshaft such that the power piston reciprocates through a power stroke and an exhaust stroke of a four stroke cycle during a single rotation of the crankshaft;
• a compression piston slidably received within a second cylinder and operatively connected to the crankshaft such that the compression piston reciprocates through an intake stroke and a compression stroke of the same four stroke cycle during the same rotation of the crankshaft;
• and
• a first piston-cylinder axis along which the power piston reciprocates within the first cylinder, wherein the first piston-cylinder axis has an offset from the crankshaft axis such that the first piston-cylinder axis does not intersect the crankshaft axis;
• wherein the power piston leads the compression piston by a phase shift angle that is substantially equal to or greater than 20 degrees.

An engine comprising:

• a crankshaft, rotating about a crankshaft axis of the engine;
• a power piston slidably received within a first cylinder and operatively connected to the crankshaft such that the power piston reciprocates through a power stroke and an exhaust stroke of a four stroke cycle during a single rotation of the crankshaft;
• a compression piston slidably received within a second cylinder and operatively connected to the crankshaft such that the compression piston reciprocates through an intake stroke and a compression stroke of the same four stroke cycle during the same rotation of the crankshaft;
• and
• a piston-cylinder axis along which the compression piston reciprocates within the second cylinder, wherein the piston-cylinder axis has an offset from the crankshaft axis such that the piston-cylinder axis does not intersect the crankshaft axis;
• wherein the power piston leads the compression piston by a phase shift angle that is substantially equal to or greater than 20 degrees.

An engine comprising:

• a crankshaft, rotating about a crankshaft axis of the engine;
• a power piston slidably received within a first cylinder and operatively connected to the crankshaft such that the power piston reciprocates through a power stroke and an exhaust stroke of a four stroke cycle during a single rotation of the crankshaft;
• a compression piston slidably received within a second cylinder and operatively connected to the crankshaft such that the compression piston reciprocates through an intake stroke and a compression stroke of the same four stroke cycle during the same rotation of the crankshaft;
• and
• a first piston-cylinder axis along which the power piston reciprocates within the first cylinder, wherein the first piston-cylinder axis has an offset from the crankshaft axis such that the first piston-cylinder axis does not intersect the crankshaft axis;
• wherein the offset of the first piston-cylinder axis is such that the crankshaft must rotate at least 20 degrees past the point where the power piston reaches top dead center, before the power piston can reach a firing position.

An engine comprising:

• a crankshaft, rotating about a crankshaft axis of the engine;
• a power piston slidably received within a first cylinder and operatively connected to the crankshaft via first linkage system such that the power piston reciprocates through a power stroke and an exhaust stroke of a four stroke cycle during a single rotation of the crankshaft;
• a compression piston slidably received within a second cylinder and operatively connected to the crankshaft via second linkage system, wherein the first and second linkage systems share no common mechanical link, and such that the compression piston reciprocates through an intake stroke and a compression stroke of the same four stroke cycle during the same rotation of the crankshaft;
• a first piston-cylinder axis along which the power piston reciprocates within the first cylinder;
• and
• a second piston-cylinder axis along which the compression piston reciprocates within the second cylinder;
• wherein one of the first and second piston-cylinder axes has an offset from the crankshaft axis.