The Coates Spherical Rotary Valve System (CSRV) replaces traditional poppet valves and all their associated parts: springs, guides, seats, retainers, cotters, pushrods, cam followers, camshaft, camshaft bearings.

Comparison of CSRV and conventional poppet valves. Click diagram to enlarge. Click here for animation.

The CSRV System comprises only two moving shafts and does not utilize oil pressure fed bearings, or oil spray; no engine oil is present in the head of the CSRV Engine. This means the engine oil does not see the hottest parts of the engine—the exhaust poppet valves. These extremely hot components usually are engine oil spray-cooled, Coates notes. This heat would breakdown the engine oil, lowering its viscosity, and usable life. With the CSRV incorporated in the engine design, oil change intervals are extended to approximately 50,000 miles or more, the company claims.

The valves rotate on ceramic carbon bearings with no oil lubrication, and the spheres do not make contact with any part of the housing. The seals are a floating type and are also made of a ceramic material. They have two piston rings and are floating in a small cylinder-type chamber, and are activated by the compression and the combustion strokes of the engine which allows 100% sealing effectiveness, when compressed, Coates says.

The CSRV rotates away from the extreme heat of the combustion chamber, reducing the possibility of hot spots in the combustion chamber, thus allowing for higher compression chamber ratios to be incorporated in the design of a combustion engine. This results in a higher thermal efficient engine and a more complete combustion, while reducing emissions.

Some Coates Spherical Rotary Combustion Engines are at 12 to 1, 13 to 1, 14 to 1 and 15 to 1 compression ratios depending on the application.

Coates currently is working on a v-twin 1600cc air-cooled CSRV engine for delivery to China for testing and demonstration for the Chinese Government.