Hey guys please look this over and tell me what you think.
Is there anything missing? Improvements? etc.?

Paul Lamar

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The Wankel rotary consists of a three sided rotor moving in a modified oval
chamber or rotor housing. The shape of the chamber is a mathematical
construction called an epitrochoid. These curves were studied by Durer
(1525), Desargues (1640), Huygens (1679), Leibniz, Newton (1686), L'Hospital
(1690), Jakob Bernoulli (1690), la Hire (1694), Johann Bernoulli (1695),
Daniel Bernoulli (1725), Euler (1745, 1781). An epitrochoid appears in
Durer's work Instruction in Measurement with Compasses and Straight Edge
(1525). Nothing new here.

It is also called a Roulette. If you have ever seen a Roulette wheel in
motion at a casino you have seen a Wankel engine in motion sort of. To
describe the Mazda rotary epictrochoid shaped housings the diameter of the
ball is about 1.181 and the diameter of the track (Roulette wheel race) is
9.375 inches. The circuitous path a point on the surface of the ball makes
as it rotates defines the epitrochoid shape. This 9.375 inch dimension is
also the height of the inside of the Mazda rotor housing. The necked down
dimension of the Mazda rotor housing is 9.375 minus twice the ball diameter
or about seven inches. The radius of the ball is called the "e" dimension

of
the Wankel engine. It is also the stroke of the e-shaft so to speak. Think
of the rotary as a large bore piston engine with a very short stroke except
it does not reciprocate.  Of course an apex seal's path MUST match the inner
surface epitrochoid curve of the rotor housing as the rotor MUST rotate at
one third of the e-centric shaft rotation.  Also the radius of the rotor
MUST be seven times the "e" dimension. A variation in any of these
relationships would cause the engine to jam.

Written by Dave Mix.
The gears inside the rotary are a means of  "timing"  the position and
orientation of the rotor.  This is very much akin to the way  "timing"
gears ( or chains or cog belts )  "time"  the position of the CAMshaft in

a
piston engine.  *** POWER is not transmitted in either case, only the exact
POSITION is determined.***  This  "timing"  is necessary to put the piston
engine valves in the proper place at the proper time.  In the rotary this
"timing" is necessary to put the rotor in the proper place and orientation
at the proper time.
Paul Lamar

The roulette analogy doesn't do anything for me. I've only seen
roulette on TV and they always show a ball bouncing and then dropping
into a slot on the edge of a wheel.

I don't get the picture either.

-Jeff (Jeff Martin)

Nevertheless "Roulette" , it is an excelent write-up. It shows the two functions of the stationary gears, which are " rotor timing" and providing

a "continous bearing" for the rotor torque arm(functionally spoken) to the

e-shaft.

Richard Sohn
N2071U

The drawing is wonderful; it contains an amazing amount of information so
intuitively displayed, that it looks simple.  Before I saw the drawing, I
could describe the processes going on in the motor, but the required
mathematical precision was filed under "Take the engineer's word for this."

Thanks for the insight.  Actually, it IS simple; I just had not seen it
before.

Grant

Thanks Grant. That was one of those "I see the light moments." :)