Internal-combustion engine and drive system

An internal combustion engine in which a valve is opened and closed when a piston reciprocates in a cylinder, comprising:

• as the valve, an exhaust valve and an intake valve, wherein
• the internal combustion engine performs, during three reciprocations of the piston:
• a first-stage intake stroke in which intake is performed by opening the intake valve and moving down the piston;
• a first-stage compression stroke in which compression is performed by moving up the piston in a state where the intake valve and exhaust valve are closed;
• a first-stage ignition stroke in which first-stage ignition is performed when the piston reaches a top dead center or the vicinity of the top dead center;
• a first-stage combustion stroke in which combustion is performed by the first-stage ignition, and the piston moves down;
• a first-stage exhaust stroke in which exhaust is performed by opening the exhaust valve when the piston moves down;
• a scavenging and intake stroke in which scavenging and intake is performed until the piston moves up again by opening the intake valve in a state where the exhaust valve is open and before the piston reaches a bottom dead center;
• a second-stage compression stroke in which compression is performed by closing both of the exhaust valve and the intake valve and moving up the piston;
• a second-stage ignition stroke in which ignition is performed when the piston reaches the top dead center or the vicinity of the top dead center;
• a second-stage combustion stroke in which combustion is performed by the second-stage ignition and the piston moves down;
• and
• a second-stage exhaust stroke in which exhaust is performed by opening the exhaust valve when the piston moves down,
• wherein the internal combustion engine repeatedly performs these operations corresponding to three reciprocations of the piston.