Patent ID: 8291872

Claim:
A method of operating an internal combustion engine having a piston reciprocally movable in a cylinder to provide a six-stroke cycle, the method comprising the steps of: performing a first stroke cycle in which a piston travels in a cylinder in a direction toward a crankshaft, with an intake valve of the cylinder in an open condition, an exhaust valve of the cylinder in a closed condition, and an air-fuel mixture introduced via the intake valve into the cylinder; performing a second stroke cycle, in which the intake valve and the exhaust valve are both closed, and the piston travels in the cylinder in a direction away from the crankshaft to compress the air-fuel mixture, with combustion of the fuel-air mixture beginning towards the end of the compression stroke; performing a third stroke cycle, in which the intake valve and the exhaust valve are both closed, with the piston traveling toward the crankshaft while the air-fuel mixture is combusting and expanding; performing a fourth stroke cycle having: (a) a first event that begins substantially simultaneous with a bottom dead center position of the piston, in which the intake valve is closed and the exhaust valve is open, with the piston traveling away from the crankshaft, (b) a second event in which the exhaust valve and the inlet valve are each closed, with the piston traveling away from the crankshaft and compressing exhaust gases in the cylinder, the second event ending when the piston is proximate a top dead center position of the piston, and (c) a third event that begins substantially simultaneous with the top dead center position of the piston, in which the exhaust valve and the inlet valve are each closed and a volume of water is injected from a water injector into the cylinder during the third event; performing a fifth stroke cycle, in which the intake valve and the exhaust valve are closed, with the piston traveling toward the crankshaft while the water is vaporized and steam pressure forces the piston towardly; and performing a sixth stroke cycle, in which the intake valve is closed and the exhaust valve is open, in which the piston traveling away from the crankshaft, and in which the contents of the cylinder are exhausted from the cylinder via the exhaust valve.