A rocker arm comprises a first outer arm and a second outer arm joined by a pivot body, the first outer arm comprising an inner side, the inner side comprising a limiting surface. An actuatable latch mechanism is within the pivot body. A first inner arm and a second inner arm are joined by a latch arm. An axle joins the first inner arm and the second inner arm to pivot between the first outer arm and the second outer arm. A second axle is between the first inner arm and the second inner arm. A pin extends from the second axle towards the first outer arm, and the pin is configured to pivot towards and away from the limiting surface when the first inner arm and the second inner arm pivot between the first outer arm and the second outer arm.

A rocker arm comprises a first outer arm and a second outer arm joined by a pivot body, the first outer arm comprising an inner side, the inner side comprising a limiting surface. An actuatable latch mechanism is within the pivot body. A first inner arm and a second inner arm are joined by a latch arm. An axle joins the first inner arm and the second inner arm to pivot between the first outer arm and the second outer arm. A second axle is between the first inner arm and the second inner arm. A pin extends from the second axle towards the first outer arm, and the pin is configured to pivot towards and away from the limiting surface when the first inner arm and the second inner arm pivot between the first outer arm and the second outer arm.

A four-stroke opposed piston engine contains a drive train containing two outer crank shaft gears, and two inner synchro gears, wherein the inner synchro gears are twice the diameter of the outer crank shaft gears. Additionally, novel piston faces are presented that when fixed on opposed pistons, create annular cavities that form advantageous combustion chambers when the pistons are at top dead center.

A valve actuation system comprises a first motion transfer mechanism operatively connected to a first valve actuation motion source and to the at least one engine valve, a second motion transfer mechanism operatively connected to a second valve actuation motion source; and a selectable coupling mechanism between the first and second motion transfer mechanisms. The coupling mechanism is operable in a first state where first valve actuation motions are conveyed to the at least one engine valve via the first motion transfer mechanism, and a second state where second valve actuation motions are additionally conveyed to the at least one engine valve via the second motion transfer mechanism, the coupling mechanism and the first motion transfer mechanism. During a handoff between the first and second valve actuation motions or vice versa, a difference in valve actuation velocities of the first and second valve actuation motions does not exceed a threshold.

A valve actuation system comprises a first motion transfer mechanism operatively connected to a first valve actuation motion source and to the at least one engine valve, a second motion transfer mechanism operatively connected to a second valve actuation motion source; and a selectable coupling mechanism between the first and second motion transfer mechanisms. The coupling mechanism is operable in a first state where first valve actuation motions are conveyed to the at least one engine valve via the first motion transfer mechanism, and a second state where second valve actuation motions are additionally conveyed to the at least one engine valve via the second motion transfer mechanism, the coupling mechanism and the first motion transfer mechanism. During a handoff between the first and second valve actuation motions or vice versa, a difference in valve actuation velocities of the first and second valve actuation motions does not exceed a threshold.

Internal combustion engines having a split crankshaft are disclosed. The engines may also have non-circular, preferably rectangular, cross-section pistons and cylinders. The pistons may include a skirt with a field of pockets that provide a ringless, non-lubricated, seal equivalent. The pistons also may have a domed piston head with depressions thereon to facilitate the movement of air/charge in the cylinder. The engines also may use multi-stage poppet valves in lieu of conventional poppet valves. The engines may use the pumping motion of the engine piston to supercharge the cylinder with air/charge. The engines also may operate in an inverted orientation in which the piston is closer to the local gravitationally dominant terrestrial body's center of gravity at top dead center position than at bottom dead center position.

Internal combustion engines having a split crankshaft are disclosed. The engines may also have non-circular, preferably rectangular, cross-section pistons and cylinders. The pistons may include a skirt with a field of pockets that provide a ringless, non-lubricated, seal equivalent. The pistons also may have a domed piston head with depressions thereon to facilitate the movement of air/charge in the cylinder. The engines also may use multi-stage poppet valves in lieu of conventional poppet valves. The engines may use the pumping motion of the engine piston to supercharge the cylinder with air/charge. The engines also may operate in an inverted orientation in which the piston is closer to the local gravitationally dominant terrestrial body's center of gravity at top dead center position than at bottom dead center position.

A sensor mounting structure for an engine is provided. The sensor mounting structure offers a greater flexibility in mounting a sensor which detects an operation of an actuation member disposed at an inner wall spaced apart from an outer wall of a cylinder head of a valve gear. A sensor mounting structure for an engine includes a valve gear provided at a cylinder head and a sensor detecting an operation of the valve gear. The sensor is mounted on a sensor mounting hole formed at a head inner wall of the cylinder head covered with a cylinder head cover.

A valve actuation system comprises a first motion transfer mechanism operatively connected to a first valve actuation motion source and to the at least one engine valve, a second motion transfer mechanism operatively connected to a second valve actuation motion source; and a selectable coupling mechanism between the first and second motion transfer mechanisms. The coupling mechanism is operable in a first state where first valve actuation motions are conveyed to the at least one engine valve via the first motion transfer mechanism, and a second state where second valve actuation motions are additionally conveyed to the at least one engine valve via the second motion transfer mechanism, the coupling mechanism and the first motion transfer mechanism. During a handoff between the first and second valve actuation motions or vice versa, a difference in valve actuation velocities of the first and second valve actuation motions does not exceed a threshold.

A valve actuation system comprises a first motion transfer mechanism operatively connected to a first valve actuation motion source and to the at least one engine valve, a second motion transfer mechanism operatively connected to a second valve actuation motion source; and a selectable coupling mechanism between the first and second motion transfer mechanisms. The coupling mechanism is operable in a first state where first valve actuation motions are conveyed to the at least one engine valve via the first motion transfer mechanism, and a second state where second valve actuation motions are additionally conveyed to the at least one engine valve via the second motion transfer mechanism, the coupling mechanism and the first motion transfer mechanism. During a handoff between the first and second valve actuation motions or vice versa, a difference in valve actuation velocities of the first and second valve actuation motions does not exceed a threshold.