Patent ID: 8156904

Claim:
An engine, comprising: a crankshaft rotatable about a crankshaft axis; a compression piston slidably received within a compression cylinder and operatively connected to the crankshaft such that the compression piston is operable to reciprocate through an intake stroke and a compression stroke during a single rotation of the crankshaft; an expansion (power) piston slidably received within an expansion cylinder and operatively connected to the crankshaft such that the expansion piston is operable to reciprocate through an expansion stroke and an exhaust stroke during a single rotation of the crankshaft; and a variable volume crossover passage interconnecting the compression and expansion cylinders, said crossover passage including a variable volume housing to controllably regulate the air flow from the compression cylinder to the expansion cylinder; whereby regulating the air flow from the compression cylinder to the expansion cylinder regulates the air pressure.