An engine includes a compression chamber that intakes and compresses working fluid; an expansion chamber that expands and exhausts working fluid; and a transfer chamber that receives working fluid from the compression chamber and transfers working fluid to the expansion chamber, wherein an internal volume of the transfer chamber decreases during the transfer of working fluid.

An engine includes a compression chamber that intakes and compresses working fluid; an expansion chamber that expands and exhausts working fluid; and a transfer chamber that receives working fluid from the compression chamber and transfers working fluid to the expansion chamber, wherein an internal volume of the transfer chamber decreases during the transfer of working fluid.

A uniflow engine includes a cylinder having a cylinder wall, a volume exterior to the cylinder, at least one channel extending between the cylinder wall and the volume, and a valve outside of the cylinder configured to open and close flow communication between the cylinder and the volume through the channel.

A two stroke internal combustion engine having a piston reciprocating in a cylinder between TDC and BDC positions to influence a crank shaft with help of a connecting rod. A Rotational Valve (RV) associated with the cylinder body selectively altering the timing and duration of opening and closing of cylinder intake and exhaust ports. The said rotational Valve may be associated with the said crank shaft through a drive train assembly. Drive train assembly may control the Rotational Valve through electronic or mechanical means.

A reciprocating cylinder seal assembly has an elastomeric seal with a radially inwardly directed oil sealing lip and a radially inwardly directed gas sealing lip, wherein both lips are in elastomeric-to-metal sealing contact with a reciprocating engine liner. The assembly further has a U-shaped seal retainer that is attached to the elastomeric seal, where the U-shaped seal retainer is placed in direct intimate contact with a cylindrical engine housing. The U-shaped seal retainer and a reciprocating engine housing may be separated by and be in contact with a major portion of a J-shaped gas shield with a hook portion that is located between the oil sealing lip and a manifold port, where the hook portion of the J-shaped gas shield has a metal backer ring embedded in it.

A reciprocating cylinder seal assembly has an elastomeric seal with a radially inwardly directed oil sealing lip and a radially inwardly directed gas sealing lip, wherein both lips are in elastomeric-to-metal sealing contact with a reciprocating engine liner. The assembly further has a U-shaped seal retainer that is attached to the elastomeric seal, where the U-shaped seal retainer is placed in direct intimate contact with a cylindrical engine housing. The U-shaped seal retainer and a reciprocating engine housing may be separated by and be in contact with a major portion of a J-shaped gas shield with a hook portion that is located between the oil sealing lip and a manifold port, where the hook portion of the J-shaped gas shield has a metal backer ring embedded in it.

An internal combustion engine can include a piston moving in a cylinder and a junk head disposed opposite the piston head in the cylinder. The junk head can optionally be moveable between a higher compression ratio position closer to a top dead center of the piston and a lower compression ratio position further from the top dead center position of the piston. At least one intake port can deliver a fluid comprising inlet air to a combustion chamber within the cylinder. Combustion gases can be directed out of the combustion volume through at least one exhaust port. One or both of the intake port and the exhaust port can be opened and closed by operation of a sleeve valve that at least partially encircles the piston. Related articles, systems, and methods are described.

An internal combustion engine can include a piston moving in a cylinder and a junk head disposed opposite the piston head in the cylinder. The junk head can optionally be moveable between a higher compression ratio position closer to a top dead center of the piston and a lower compression ratio position further from the top dead center position of the piston. At least one intake port can deliver a fluid comprising inlet air to a combustion chamber within the cylinder. Combustion gases can be directed out of the combustion volume through at least one exhaust port. One or both of the intake port and the exhaust port can be opened and closed by operation of a sleeve valve that at least partially encircles the piston. Related articles, systems, and methods are described.

An engine comprises at least one cylinder, at least one piston reciprocatable within the at least one cylinder, at least one intake port through a wall of the at least one cylinder, at least one exhaust port through a wall of the at least one cylinder, at least one reciprocatable sleeve valve within the at least one cylinder for controlling porting of one or both of the at least one intake port and the at least one exhaust port, at least one shaft configured to be rotated by reciprocal motion of the at least one piston, a piston drive means coupled to and reciprocatable with the least one piston and a sleeve valve drive means coupled to and reciprocatable with the at least one reciprocatable sleeve valve. An axis of reciprocation the sleeve valve drive means is spaced from and parallel to an axis of reciprocation of the piston drive means of the at least one piston and the axis of reciprocation the sleeve valve drive means is positioned around the circumference of the shaft from the axis of reciprocation of the piston drive means of the at least one piston. This may allow the engine to be more compact and have a reduced physical size compared to some known engines.

An engine includes a compression chamber that intakes and compresses working fluid; an expansion chamber that expands and exhausts working fluid; and a transfer chamber that receives working fluid from the compression chamber and transfers working fluid to the expansion chamber, wherein an internal volume of the transfer chamber decreases during the transfer of working fluid.