I'm no engineer, but I do have thoughts on this. Maybe
in part because I tried to develop a camless drivetrain
in high school and, while it was a complete disaster,
I did live through the experience.
> I can't see how you can get the airflow you want from air
> trying to make it through a spinning ball like that.
Well, if the "ball" was basically a hemisphere, and of
reasonable size, it could provide for a large open gap
when perpindicular to the piston. At that moment, air
could get in much more directly than in current designs,
where it has to flow around a valve. The hemishpere
could also be vaned to help reduce weird aerodynamics.
> That means the air would basically be spinning as it entered the
> combustion chamber, and would be aimed at different points as
> the ball spins.
Not necessarily. The spinning ball could in fact act as a
mini supercharger, forcing air in as it closes. In that case,
flow would not be laminar, bout would at least be chaotic.
> Also, how do you seal against combustion chamber pressure
> with a spinning ball?
The same way you do with valves. The ball is *inside* the
cylinder, so pressire just forces it against the head and
therefore helps to seal the cylinder. Sure, there'd be a
trick to keeping that mating lubricated (err...), but that's
not all that difficult if you can guarantee tolerances and
know the materials that you're working with.
> And remember it will change temperatures rapidly
> as well, and will have a large temperature gradient in the
> ball itself. Also, how would you oil it to keep the oil out
> of the combustion chamber?
That all sounds pretty similar to the problems with valves.
I agree that we're years away, and I personally think that
computer (rather than drivetrain) controlled iris-type
solenoids may be a more promising future, but this is
certainly an interesting design.
Cheers
-b
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