Browse Publications Technical Papers 2002-32-1828
2002-10-29

59 The Rotating Cylinder Valve 4-Stroke Engine A Practical Alternative 2002-32-1828

The Rotating Cylinder Valve (RCV) Engine is a novel 4 cycle engine that is a practical alternative to conventional 2 and 4 stroke designs, in particular for small capacity single cylinder applications. It is primarily intended to address applications where emissions legislation is forcing manufacturers to abandon the traditional carburetted 2 stroke. It has particular benefits for the moped/light motorcycle market.
The engine operates on a simple principle. The cylinder liner is rotated around the piston at half engine speed via a pair of bevel gears. A port in the side of this cylinder indexes with inlet and exhaust ports in the surrounding casing. This rotary valve serves the cylinder as the engine cycles through the conventional 4 stroke cycle.
The main technical issue that has been addressed is the design of a practical rotary valve seal. The RCV seal design provides a gas-tight compression seal, accommodates large thermal distortions, and takes up both production tolerance and longer term wear. The design is low cost, and simple to assemble and service. The rest of the components within the engine are conventional.
The RCV engine offers all the normal emissions advantages that a 4 stroke has over a conventional 2 stroke. It also has many benefits compared to a conventional poppet valve 4 stroke, in particular a predicted production cost comparable to a conventional 2 stroke.
The design has other significant technical benefits, including excellent thermal distribution, and good breathing characteristics. For moped applications the rear wheel power output of the engine will be competitive with current 2 stroke designs and exceeds the power output of typical small capacity poppet valve 4 stroke designs.

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