Centrifugal force of a rotating object is MVVR. Where V is the
velocity, and R the radius and M is mass.
This means that unless C.G. is matched exactly, it is impossible to
ballance the engine at different speed.
Fortunately, I think the C.G. Of the rotor travels in a circle.
Therefore it is van be balanced by a weight at the C.G. path of the
rotor. The same goes for the imbalance of the eshaft.
Since counter weight is located only at the end of the engine, I
think you will get from limited twisting on the shaft.
That's IMHO. No guarantee on accuracy.
Henry Nee 於 2015/4/17 下午11:20，"paul" <
rotaryeng@earthlink.net 寫道：
Hi,
Can you please explain the problem and solution of balancing when
using a cut down e-shaft with single rotor 1/2 Mazda 13b engine.
Regards Zahid
Balance is controlled by these equations. The Wankel is not just
statically balanced but dynamically balanced as well.
In a single rotor engine the counterbalance weights must provide a
STATIC balance for the e-shaft eccentric and its rotor and must
also account for the DYNAMIC wobble caused because the static
counter weights are not located at the mechanical centres of the
rotor and the eccentric. It is impossible to do this.
They must be mathematically sized relative to their lateral
position from the rotor and eccentric centre line.
Paul Lamar
the Tracy ISO is physically attached to the flywheel. Does that
need to be brought in to balance equation as extra mass to mF
(front counter weight) or mR (mass Rear Counterweight)?
Regards Zahid
The rear counter weight is hiding behind the ISO.
Paul Lamar
Here is how I solved some of the balancing issues. There are a
whole lot of issues interacting when building a new engine
configuration. Weight control influences almost everything. A
single rotor engine certainly requires a considerable flywheel, if
one wants the idle speed somewhere below 3000 RPM. I integrated the
rear balance weight in the flywheel (picture). The front balance
weight I modified with tungsten inserts before dynamic balancing. I
ended up with a clean rotating setup. My engine is based on 12A
rotor and housing, so I do not have any direct comparison to 13B
size parts. FWIW.
Richard Sohn N2071U
http://www.fairpoint.net/~res12/home.html
Hi Richard, I have read some postings where some have machined a
single rotor eccentric shaft from a 2 rotor unit. Paul mentions the
shaft needs to be hardened after machining. Could you give a
overview of the process you used to build your shaft ?
Thanks, Steve Carlisle
Here is what I did.
On the first e-shaft I concerted, I left the oil pump side of the
shaft with the front lobe unchanged. After machining the rear end
of the shaft to my mods, I only had one bearing surface to create.
I picked an inner ring of a INA needle bearing with an outer
diameter the same as the original MAZDA bearing, and pressed it on
the shaft. As it turned out, it was a solution, which never failed
during all the ground testing of the first engine I build, with a
run time of around 50hrs. I did not consider this a solution for a
final, flyable configuration. The solution I have in the engine
now is a case hardened bearing section. The biggest problem was
finding someone for the case hardening and grinding who was willing
to do it for and affordable cost. FWIW
Richard Sohn N2071U
http://www.fairpoint.net/~res12/home.html
I misunderstood the last email by Richard Sohn. He was referring
to case hardening process for e shaft . I thought he was referring
to case hardening for bearing. So please do not publish my last
email.
Zahid Rahman
I am thinking, since the rotor rotates at one third the speed of the
esfaft. One needs a 3:1 reduction gear on the counter weight to matched the
rotor's rotation speed.
Corrections welcome!
Henry Nee
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