A possible different approach?

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RSD

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A thought occurred to me - it probably couldn't be done but if I don't ask...

Instead of using a PRSU and all of the problems associated with that, could the gears in the rotor and on the eccentric shaft be changed to ones that result in the eccentric shaft rotating slower so that a PSRU isn't needed? Either changing the gears themselves or custom machined billet rotors etc?
 

Hot Wings

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A thought occurred to me - it probably couldn't be done but if I don't ask...
This has been done in the past but the engine was designed with this in mind. Unfortunately a 2 to 1 reduction, as is needed for the camshaft (eccentric), is not the best ratio to use for a PSRU. The idea is not new but the reason we don't see them more is that it doesn't work out well in the real world.
 

RSD

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This has been done in the past but the engine was designed with this in mind. Unfortunately a 2 to 1 reduction, as is needed for the camshaft (eccentric), is not the best ratio to use for a PSRU. The idea is not new but the reason we don't see them more is that it doesn't work out well in the real world.
Ah OK. I think what you are saying is that because of the eccentric camshaft design the available ratios are only multiples of 1 - i.e. 2:1, 3:1 etc, and so the rotor/camshaft gearing couldn't be made to 2.6:1 for instance?
 

pictsidhe

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Are you able to elaborate a bit more?
In order for the rotor to move in the correct orbit, the eccentric shaft must make one revolution per firing cycle. This is 3x the rotation speed of the rotor. The rotor is not geared to the eccentric, but to the stator. Change the gears and the motion will no longer be epitrochoidal. It won't work, even badly.
 

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There may be a language problem here? Eccentric shaft = balance shaft, camshaft, or Wankel crank shaft?
 

TFF

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First off you have to keep the four stroke cycle. You can’t change the ratio or the engine timing is wrong. The Continental Tiara used the timing gears as the gear reduction. Free 2-1 gearing. BUT the prop inertia would lead or lag the camshaft through the gear lash. The engine would surge up or down without perfect timing gears. New gears would be ok but as they wore it got worse and worse.
 

Vigilant1

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There may be a language problem here? Eccentric shaft = balance shaft, camshaft, or Wankel crank shaft?
A Wankel "eccentric shaft" serves the function of a crankshaft. No camshaft in a Wankel (no valves).

That Felix Wankel even figured out how to make all those things happen inside that engine is a wonder to me. I suspect hallucinogens played a key role in the design.
 
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