A steel piston achieving increased thermal brake efficiency in an internal combustion engine is provided. The piston includes a crown presenting a combustion surface, an outer side wall depending from the combustion surface, an outer cooling gallery, and an undercrown cooling gallery. The outer cooling gallery extends circumferentially along the outer side wall beneath the combustion surface. According to one embodiment, the outer cooling gallery is sealed and filled with air, argon, helium, xenon, or carbon dioxide as a cooling media. In this embodiment, the undercrown cooling gallery is filled with air as a cooling media and includes an open inlet hole having a diameter being from 2% to 4% of an outer diameter of the piston. Alternatively, the undercrown cooling gallery is filled with air, argon, helium, xenon, or carbon dioxide as a cooling media, and the inlet hole is sealed.

A device for internal cooling and pressurization of rotary engine, comprising: a mechanical charger, a charger outlet tube, a core cooling intake tube, an engine air intake tube, a first valve, a second valve, and a third valve. The mechanical charger is mounted in a ventilated place. The charger outlet tube is used to dispense air, and the charger outlet tube has two sides, with one side coupled to the mechanical charger. The core cooling intake tube is connected to another side of the charger outlet tube, and is used to dispense air. The engine air intake tube is connected to another side of the charger outlet tube. The device for cooling and pressurization of rotary engine is capable of achieving improved cooling and performance of rotary engine, through switching a plurality of valves, in automatic control manner and/or in remote control manner.

A combustible fluid-operated orbital engine having sets of cooperating cylinder and piston members with respective parallel axes of rotation. Respective cylinder and piston carrier wheels with respective axes of rotation parallel to the piston/cylinder axes of rotation carrying the pistons/cylinders orbitally and at all times in opposed relation on a common longitudinal axis along intersecting counter paths. Redundant belts/sprockets supported by the cylinder and piston carrier wheels rotate the pistons/cylinders counter to their circular motion direction to maintain their opposed relation for their periodic interfittment when their respective paths intersect. A combustible fluid supply is provided to the cylinder member for combustion coincident with the periodic interfittment. An air supply is provided to the cylinder member for purging exhaust gases and/or supercharging combustion gases. A sealing system that includes a non-metallic flexible seal is located either proximate the entry of each cylinder or proximate an end portion of each piston.

A combustible fluid-operated orbital engine having sets of cooperating cylinder and piston members with respective parallel axes of rotation. Respective cylinder and piston carrier wheels with respective axes of rotation parallel to the piston/cylinder axes of rotation carrying the pistons/cylinders orbitally and at all times in opposed relation on a common longitudinal axis along intersecting counter paths. Redundant belts/sprockets supported by the cylinder and piston carrier wheels rotate the pistons/cylinders counter to their circular motion direction to maintain their opposed relation for their periodic interfittment when their respective paths intersect. A combustible fluid supply is provided to the cylinder member for combustion coincident with the periodic interfittment. An air supply is provided to the cylinder member for purging exhaust gases and/or supercharging combustion gases. A sealing system that includes a non-metallic flexible seal is located either proximate the entry of each cylinder or proximate an end portion of each piston.

In a two-stroke engine including a scavenging port (43b) having an open end (42d) opening out in a side wall of the cylinder bore (3a) and communicating with a crank chamber (2a), the open end being configured to be closed and opened by the piston (22), a fuel injection device (71) is mounted on the engine main body so as to inject fuel onto a back side of the piston and/or a part of the side wall of the cylinder bore located under the piston via the open end of the scavenging port or via the open lower end of the cylinder bore. The fuel deposited on the surfaces of the piston and the cylinder inner wall promotes the cooling of such parts.

An opposed-piston engine includes pistons, each piston having an annular cavity in the piston's sidewall and positioned between its crown and ring grooves to block transfer of heat from the crown to the piston body.