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 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 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.

A valve for an overhead cam engine includes a valve sleeve, a valve cylinder, and a valve spring. The valve sleeve is cylindrical and has an annular shoulder and ports designed to permit flow of fuel and gases into and out of an internal combustion chamber. The valve cylinder includes a cylindrical body and a top cap. The top cap includes a contact surface to be engaged by a cam lobe and an annular projection. The valve spring is positioned about the cylindrical body and between the annular projection and the annular shoulder. The valve spring is designed to expand and move the valve cylinder partially out of the valve sleeve to unblock the ports and open the valve. The valve spring is designed to be compressed to permit the cam lobe to move the valve cylinder into the valve sleeve to block the ports and close the valve.

A valve for an overhead cam engine includes a valve sleeve, a valve cylinder, and a valve spring. The valve sleeve is cylindrical and has an annular shoulder and ports designed to permit flow of fuel and gases into and out of an internal combustion chamber. The valve cylinder includes a cylindrical body and a top cap. The top cap includes a contact surface to be engaged by a cam lobe and an annular projection. The valve spring is positioned about the cylindrical body and between the annular projection and the annular shoulder. The valve spring is designed to expand and move the valve cylinder partially out of the valve sleeve to unblock the ports and open the valve. The valve spring is designed to be compressed to permit the cam lobe to move the valve cylinder into the valve sleeve to block the ports and close the valve.