An internal combustion engine may include an engine block, a cylinder within the engine block, and a piston within the cylinder. The piston may have an outer peripheral wall, and a groove in the outer peripheral wall of the piston may have a first edge and a second edge spaced from the first edge. The piston may have a piston ring in the groove, and the piston ring may have a shape that meanders within the groove, such that the shape of the piston ring differs from a shape of the groove and such that the piston ring does not substantially fill the groove. The piston ring may be constructed of a material that when subjected to heat causes a shape of the meanderings to change, thereby enabling the piston ring to expand in an axial direction of the piston, between the edges of the groove.

A reciprocating compressor. A hollow cylinder tube contains a piston assembly having two pistons connected by a piston rod. At each end of the cylinder tube is an outer chamber between an end plate and an outer end of the proximate piston. These two outer chambers and the outer ends of the pistons define a power cylinder at each end of the cylinder tube. In the mid-portion of the cylinder tube, a center divider is situated between the pistons and has an aperture that allows the piston rod to reciprocate through it. The two inner chambers formed thereby and the inner ends of the pistons define two compression cylinders in the mid-portion of the cylinder tube. The two compression chambers share a suction manifold and a discharge manifold, but have independently operating suction and discharge valves.

A combustion driven fastener hand tool is disclosed having an extruded front body component including two to three parallel bores. A first bore forms a cylinder for the piston which drives the fastener. A second bore forms a primary combustion chamber in which a fuel and air mixture is ignited and directed into the adjacent piston cylinder. A third bore (or alternately an attached component) forms a pathway for the fuel and air mixture to be directed into the primary combustion chamber. The combustion driven fastener hand tool includes numerous other features affording improvements over the prior art.

A combustion driven fastener hand tool is disclosed having an extruded front body component including two to three parallel bores. A first bore forms a cylinder for the piston which drives the fastener. A second bore forms a primary combustion chamber in which a fuel and air mixture is ignited and directed into the adjacent piston cylinder. A third bore (or alternately an attached component) forms a pathway for the fuel and air mixture to be directed into the primary combustion chamber. The combustion driven fastener hand tool includes numerous other features affording improvements over the prior art.

A linear reciprocating engine may include a cylinder having a first combustion chamber at one end and a second combustion chamber at an opposing end, first and second cylinder heads located at an end of the first and second combustion chambers, respectively, and a double-faced piston slidably mounted within the cylinder. The engine may further include a first piston rod portion extending from a first face of the double-faced piston through the first combustion chamber, and a second piston rod portion extending from a second face of the piston through the second combustion chamber. Passageways in the piston rod portions may be configured to communicate gases between the combustion chamber and a location outside the cylinder and configured to prevent gases from being exchanged between the cylinder and a location outside the cylinder via a path that crosses both face of the piston.

A linear reciprocating engine may include a cylinder having a first combustion chamber at one end and a second combustion chamber at an opposing end, first and second cylinder heads located at an end of the first and second combustion chambers, respectively, and a double-faced piston slidably mounted within the cylinder. The engine may further include a first piston rod portion extending from a first face of the double-faced piston through the first combustion chamber, and a second piston rod portion extending from a second face of the piston through the second combustion chamber. Passageways in the piston rod portions may be configured to communicate gases between the combustion chamber and a location outside the cylinder and configured to prevent gases from being exchanged between the cylinder and a location outside the cylinder via a path that crosses both face of the piston.

The present disclosure provides an open-faced piston with a circumferential groove into which a piston ring assembly is arranged. Openings at the bottom of the circumferential groove and between a front land of the open-faced piston and the piston face are provided. The openings are arranged to allow for a combustion reaction to propagate through the volume defined between the bottom of the piston ring assembly and the piston face such that at least a portion of an air and fuel mixture located in that volume is reacted.

The present disclosure provides an open-faced piston with a circumferential groove into which a piston ring assembly is arranged. Openings at the bottom of the circumferential groove and between a front land of the open-faced piston and the piston face are provided. The openings are arranged to allow for a combustion reaction to propagate through the volume defined between the bottom of the piston ring assembly and the piston face such that at least a portion of an air and fuel mixture located in that volume is reacted.

A two-stroke cycle, turbo-driven, opposed-piston engine with one or more ported cylinders and uniflow scavenging has no supercharger. The engine includes a high pressure EGR loop and a pump in the EGR loop to boost the pressure of the recirculated exhaust products.

A linear reciprocating engine may include a cylinder having first and second combustion chambers at opposing ends, first and second cylinder heads at an end of the first and second combustion chambers, respectively, and a double-faced piston slidably mounted within the cylinder. The engine may further include an exhaust port located in a peripheral cylinder wall and at least one combustion gas inlet in a location other than the peripheral cylinder wall. The combustion gas inlet and the exhaust port may be configured to cooperate such that combustion gases introduced through the inlet are evacuated from the cylinder through the exhaust port. The double-faced piston may have an axial length from one face to an opposite face of the piston less than or equal to of a distance from at least one of the first cylinder head and the second cylinder head to the exhaust port.