Multi-Stroke Internal Combustion Engine

An internal combustion engine system for a vehicle, comprising:

• an engine body defining at least one combustion chamber having a piston disposed therein;
• a manifold coupled to the engine body and defining a fluid passage that communicates with the combustion chamber via a first valve and a second valve;
• a first cam actuator configured to open the first valve;
• a second cam actuator configured to open the second valve;
• and
• a control system configured to:
• operate the first cam actuator to repeatedly open the first valve once every four piston strokes and operate the second cam actuator to repeatedly open the second valve once every four piston strokes during a different stroke than the first valve to carry out combustion in the combustion chamber according to a two stroke cycle;
• and
• operate the first cam actuator to repeatedly open the first valve once every four piston strokes and operate the second cam actuator in an inactive lift state with the second valve so that the second valve is held closed to carry out combustion in the combustion chamber according to a four stroke cycle.

A method of operating an internal combustion engine including at least one combustion chamber having a piston disposed therein, the method comprising:

• operating the combustion chamber in a four stroke cycle by repeatedly opening a first exhaust valve of the combustion chamber once every four piston strokes via a first cam actuator while holding closed a second exhaust valve of the combustion chamber;
• operating the combustion chamber in a two stroke cycle by repeatedly opening the first exhaust valve once every four piston strokes via the first cam actuator and repeatedly opening the second exhaust valve once every four piston strokes via a second cam actuator during a different exhaust stroke than the first exhaust valve;
• and
• varying operation of the combustion chamber between the four stroke cycle and the two stroke cycle as an operating condition changes by adjusting a lift state between the second cam actuator and the second exhaust valve.