[Gasification] tar proof Rotary Cylinderhead (Philippe Raufast)

[Daniel Chisholm]

Thanks Philippe.  As Andy noted, the site doesn't provide much in the
way of interesting details.  I did not get around to reading their
patents.

It looks like a pretty interesting concept in engine valving, however
there are a number of things I ran across on the site that made me less
than 100% comfortable (their SEC filings; their claim of pre-emissions
12:1 engines producing 55% thermal efficiency; their description of
encountering a cooling problem in their exhaust valves which required
the use of 35 gallons per minute of cooling water to solve; the
extremely low specific output of their industrial engines - 855 c.i.d.
and only 174-280hp).

With respect to the tar-proofedness of this valve design, I don't see
how it would offer an intrinsic advantage over a poppet valve engine.  I
understand that tar fouls a poppet valve engine by causing the valve
stems to stick, and (perhaps to a lesser extent) fouling the intake
manifold passages.

With their rotary valving, my first thoughts about running it on a
tar-rich gas would be that tar would deposit on the intake valve sphere,
and then harden/freeze/congeal during shutdown.  This could make
starting the cold engine afterwards difficult.  I'm not sure if it would
_prevent_ the starting of the engine like a set of stuck inlet poppet
valves would, or if would merely increase the cranking effort.  Perhaps
it would only making starting more difficult, but still possible, and
perhaps the long-term amount of tar deposition would be something that
could be engineered around?  (e.g. size the starter motor and the
valvetrain drive gear to be big enough to break free a tar-seized
valvetrain under the coldest possible engine starting temperatures).



-- 
- Daniel
Fredericton, NB  Canada