The Green Engine


Robert Green's Steam Engine   The Green Engine is sold as a kit by its inventor, Robert Green of Laguna Woods, California.  The engine is advertised as being modern and efficient.  Its main attribute is a flexible shaft that transmits reciprocating motion from the pistons to a “Z” crank thus making rotary motion without using wrist pins,connecting rods, or crankshafts.  Before believing what a good invention this is the reader may wish to dwell on the fact that hundreds of millions of engines are made every year that have
apiston moving back and forth in a cylinder that obtains this motion with crankshafts, connecting rods, and wrist pins.  The other aspect of this engine that one may wish to dwell on is the fact that it is advertised as working really well with saturated steam.  With any luck I will not comment on that.

This engine does not follow modern steam engine design, which is to use poppet valves for steam intake with uniflow exhaust ports, which gives good thermal efficiency.  The Green engine uses anoscillating rotary valve with counter-flow steam, which means that there are long passages that the cold exhaust
  Robert Green's Steam Engine
steam flows through to exhaust that are then used by the hot incoming steam, causing it to lose a lot of heat before it gets to the cylinders where it can do work.
Robert Green's Steam Engine   There are other issues of sealing because the cylinder heads rotate around a ball joint that both supports the weight of that end of the engine, and seals the steam passage from the valve to the cylinder.  This appears to be a wear point that would require significant lubrication. 
Robert Green's Steam Engine

The mechanism to covert reciprocating motion to rotary motion is clever, but it does not add anything to a steam engine that would increase the efficient use of steam.

Green Engine Critique

Patent 8,096,787 page 1, page 2, page 3


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