Hi Lynn,
Felix Wankel designed it, why isn't it really a Wankel?
BR, Dave McC

Wankel says the shapes involved came to him after Christmas in 1953, and on other occasions says he was thinking of it since 1922. He built up two huge catalogs of rotary engine and compressor design shapes. The first destroyed during the war. So he had exposed himself to the work of others in a grand and organized way. He built his catalog based on the types and styles of motion involved in the design. Preferring only designs involving pure rotary motion.

 

Wankel was working for NSU designing rotating seals for small engines. NSU was making 50CC mopeds. He convinced NSU to support him in his work to develop a pure rotary motion engine. He told NSU that he had a deal with Borsig to develop both a compressor and an engine in an effort to force NSU to back his rotary ideas. His design was the KDM 53. Drehkolbenmotor, or, rotary piston engine of 1953.

 

So he had the two shapes we know of today in 1953. However his proposed design had the fuel air mixture moving through the hollow crankshaft as in the Le Rhone rotary, and spark plugs installed inside the rotor. The rotor housing would rotate in the same direction as the rotor, providing pure rotary motion. If you can imagine the outside of the engine spinning and the sealing involved to remove exhaust gasses, you can see Wankel's brain working as usual. He was known as Germany's sealer, for his work on rotary valves for aircraft engines during the war.

 

But the engineers at NSU chose to work on (in secrete from Wankel) an earlier shape, where the exterior of the engine was stationary. Wankel had discarded this design for its lack of pure rotary motion.

 

Engineers Walter Froede and Dr. Paschke instead took up work on the KKM or Kreiskolbenmotor for circuitous piston engine.

 

The original design was used as a supercharger on a 50CC NSU motorcycle to set a record at Bonneville at close to 120 MPH. Another  engine of 125CC produced 21 HP at 15,000 RPM and was run as high as 25,000 RPM.  

 

By 1910 there were over 2,000 patents for rotary engines on file in England, probably more in Germany. So, it worked as a compressor. It could be made to work in a laboratory with a short life. It was not at all practical for automotive use.

 

Curtis Wright contributed a great amount and Toyo Kogyo  (Mazda) perfected the engine to some extent.

 

When it came time to patent the features of the engine, it was discovered that a patent already existed. A Swiss engineer working for Truck Builder Saurer, Bernard Maillard had patented the design 11 year earlier. His design had the seals fixed in the housings rather than on the rotor tips. Same rotor and housing shapes. For reasons unknown, he gave up his rights to NSU.

 

So who invented the Wankel engine?

 

Lynn E. Hanover