A modular rotary valve apparatus includes: a plurality of separate valve barrels coupled to each other and arranged end-to-end along an axis so as to define a valve shaft, each valve barrel having an annular peripheral surface extending between forward and aft end faces, and an aperture extending transversely therethrough communicating with the peripheral surface on opposite sides.

An engine system and method of operation therefor are provided. The system is a two-stroke internal combustion engine having an exhaust valve assembly that controls the exhaust cycle relative to crankshaft timing. The exhaust valve assembly is positioned between exhaust port and an exhaust pipe. The exhaust valve assembly comprises a rotary exhaust valve and valve phasing assembly. The rotary exhaust valve comprises a valve body defining a valve void therethrough. The use of the rotary exhaust valve allows for alteration or calibration of the fixed time and location at which the intake port and exhaust port are opened and closed by the piston with respect to the respective engine cycle. Notably, while still uncovered by the piston, the exhaust port may be closed due to full misalignment of the valve void and the exhaust port, while the intake port remains open, allowing for cylinder charging.

A disk rotary valve assembly for reciprocating piston positive displacement machines, the disk rotary valve having a pair of oppositely arranged fronts, the forces on the pair of oppositely arranged fronts due to the high pressure inside the chamber cancel each other leaving the supports of the disk rotary valve unloaded and improving the sealing quality.

An engine system and method of operation therefor are provided. The system is a two-stroke internal combustion engine having an exhaust valve assembly that controls the exhaust cycle relative to crankshaft timing. The exhaust valve assembly is positioned between exhaust port and an exhaust pipe. The exhaust valve assembly comprises a rotary exhaust valve and valve phasing assembly. The rotary exhaust valve comprises a valve body defining a valve void therethrough. The use of the rotary exhaust valve allows for alteration or calibration of the fixed time and location at which the intake port and exhaust port are opened and closed by the piston with respect to the respective engine cycle. Notably, while still uncovered by the piston, the exhaust port may be closed due to full misalignment of the valve void and the exhaust port, while the intake port remains open, allowing for cylinder charging.