Internal combustion engines having pistons with one or more depressions located on the piston head to facilitate the movement of air/charge in the cylinder are disclosed. The pistons may include a skirt with a field of pockets that provide a ringless, non-lubricated, seal equivalent. The piston head also may be domed to further facilitate the movement of air/charge in the cylinder. The engines may also have non-circular, preferably rectangular, cross-section pistons and cylinders. The engines also may use multi-stage poppet valves in lieu of conventional poppet valves, and may include a split crankshaft. 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 rocker arm can comprise a first outer arm and a second outer arm joined by a pivot body. An actuatable latch mechanism is within the pivot body. An inner arm assembly comprises a latch arm. A first spring prop is on the inner arm assembly distal from the latch arm. An axle joins the inner arm assembly to pivot between the first outer arm and the second outer arm. A spring is biased against the first outer arm and against the first spring prop. The first spring prop can comprise a hooked end. Or, the first spring prop can extend laterally out from the rocker arm and parallel to the axle. The spring can comprise a one-piece spring comprising first and second coil springs connected by a lateral connector. Or, two separate torsion springs can comprising tangential spring ends extending at approximately 90 degrees.

A rocker arm can comprise a first outer arm and a second outer arm joined by a pivot body. An actuatable latch mechanism is within the pivot body. An inner arm assembly comprises a latch arm. A first spring prop is on the inner arm assembly distal from the latch arm. An axle joins the inner arm assembly to pivot between the first outer arm and the second outer arm. A spring is biased against the first outer arm and against the first spring prop. The first spring prop can comprise a hooked end. Or, the first spring prop can extend laterally out from the rocker arm and parallel to the axle. The spring can comprise a one-piece spring comprising first and second coil springs connected by a lateral connector. Or, two separate torsion springs can comprising tangential spring ends extending at approximately 90 degrees.

A method for manufacturing an internally cooled valve (2), includes providing a valve body (4) having a valve stem (6) that ends in a valve head (8). The valve body (4) has a cavity (10) that is open toward the valve head (8) and with a valve base element (12) by friction welding the valve base element (12) to the valve head (8). The valve bottom element (12) is preferably a sintered component.

A valve seat insert of an engine has a valve seating surface including an outer curved segment forming a first wear crown for contacting the valve at an early wear state, an inner curved segment forming a second wear crown for contacting the valve at a later wear state, and a linear segment extending between the outer and the inner curved segments.

A valve seat insert for a gas exchange valve controlling gas exchange of a cylinder includes an insert body having an inner peripheral surface, an outer peripheral surface, and a valve seating surface structured to contact the gas exchange valve at a closed position and profiled to limit valve recession thereof. The valve seating surface includes an arrangement of linear segments and curved segments forming crowns to contact the gas exchange valve at different wear states.

A valve seat insert of an engine has a valve seating surface including an outer curved segment forming a first wear crown for contacting the valve at an early wear state, an inner curved segment forming a second wear crown for contacting the valve at a later wear state, and a linear segment extending between the outer and the inner curved segments.

A rocker arm, comprises a first outer arm comprising a first inner side and a first outer side, the first outer side comprising a first cantilevered post. A first outer roller is mounted to the first cantilevered post. A second outer arm comprises a second inner side and a second outer side, the second inner side facing the first inner side, the second outer side comprising a second cantilevered post. A second outer roller is mounted to the second cantilevered post. A pivot body joins the first inner side to the second inner side. An actuatable latch mechanism is within the pivot body. An inner arm assembly comprises a latch arm, the latch arm pivotable adjacent the pivot body. A pivot axle joins the inner arm assembly to pivot between the first outer arm and the second outer arm.

A rocker arm, comprises a first outer arm comprising a first inner side and a first outer side, the first outer side comprising a first cantilevered post. A first outer roller is mounted to the first cantilevered post. A second outer arm comprises a second inner side and a second outer side, the second inner side facing the first inner side, the second outer side comprising a second cantilevered post. A second outer roller is mounted to the second cantilevered post. A pivot body joins the first inner side to the second inner side. An actuatable latch mechanism is within the pivot body. An inner arm assembly comprises a latch arm, the latch arm pivotable adjacent the pivot body. A pivot axle joins the inner arm assembly to pivot between the first outer arm and the second outer arm.

A rocker arm can comprise a first outer arm and a second outer arm joined by a pivot body. An actuatable latch mechanism is within the pivot body. An inner arm assembly comprises a latch arm. A first spring prop is on the inner arm assembly distal from the latch arm. An axle joins the inner arm assembly to pivot between the first outer arm and the second outer arm. A spring is biased against the first outer arm and against the first spring prop. The first spring prop can comprise a hooked end. Or, the first spring prop can extend laterally out from the rocker arm and parallel to the axle. The spring can comprise a one-piece spring comprising first and second coil springs connected by a lateral connector. Or, two separate torsion springs can comprising tangential spring ends extending at approximately 90 degrees.