Paul,

Just playing around with some ideas on TC..This concept I am sending
for
critique, understanding that this was put together in just a few
minutes...

The Idea here is to bolt the 2 exhaust housings up close and personal,
with some kind of adapter so they align with a sandwiched gear box that
resides where the compressor used to be, reducing rpm to the upper
shafts..

One shaft translates outbound to the single compressor in a housing
where it bumps the rpm back up to compressor speeds needed..the other
translate in the opposite direction that reduces rpm for the compound..

You can see built as oune complete body but don't have to tell you this
is all very modular with gear box housing and shaft housings as
separate..

All gear ratios and dimensions will adjust obliviously according to
design load and clearances..Certainly supported on the ends for
rigidity
as well...

Jim talked about getting the turbo close to the exhaust port and also
keeping the compound shaft in perfect alignment outboard, this may be a
solution....


Be nice, I am very sensitive as you know...

jeff


No jpeg attached??????

jeff

Sorry Jeff. I think you are gearing it up and not
down.

Paul Lamar

Jeff, Although I haven't done the CAD work on this I did research to
find
out what type of system to use. There are manifolds allowing
substitution
of
one large turbocharger on a 13B which  is thought to extract more power
than
the two stock turbines which are limited in size due to the tight
spacing.

Although you could connect two hot side turbines with an inconel
coupling
that is a really harsh environment and temperature expansion has to be
considered.  The major problem with turbo compounding is the 12 to 1
speed
reduction needed to connect back to the engine shaft. This is done
with a
traction drive by rotrax or more commonly with multistage spurr
gears by
procharger. To put these off the shelf items together the shaft of the
turbo supercharger would have to be replaced with one slightly
longer and
providing a coupling for the procharger gearbox. Also  needed is a
bearing
housing fabricated to fit the compressor air horn inlet with the
opposite
end adapted to the procharger gearbox. As with your model above the
engine
drives the compressor at low speed and the exhaust  turbine drives
everything at high speed. A waste gate is still needed in case the
gearbox
becomes disconnected from the engine shaft.

I have seen an advertisement on the Internet for an assembled
unit
incorporating these design features as a kit for isuzu engines which is
available only in Japan. The compounded supercharger is built by
rotrax and manufactured  in Holland.  I couldn't get any information
from
rotrax or a price. There is apparently only one size and I don't
know the
displacement of the isuzu engine it is used on or the amount of boost.

 The shaft seems like a great excuse to use your CNC lathe.
There are
steps, precision journals, tapers, and threads. It would also seem that
splines for a coupe ling might be necessary since it runs at 100K RPM.

The torque of the high speed shaft should peak under 30 ft lbs at
start up and  fall to 7 ft lbs at full speed. I like the one large
turbocharger because it can  have a larger diameter shaft which
would be
better to adapt a coupling to.

One question about your design above. Are you gearing down to the
drive shaft then gearing back up to get a different speed  on the
compressor
than the exhaust turbine rather than having them run 1 to 1 ?

george grimes



George

To answer the question, in a sense, yes...the step down at the
intersection of both turbine housings, then to step back up to the
whatever rpm needed for the optimum single compressor..

The models in this render are from another engine application for
expediency and are too large. This idea  depicted is just above drawing
on a napkin in a restaurant so a more complete model would explain more.....

Not sure about the inconel, as the center housing contains the oil
bearings and shaft that drive the impeller and in this case the the
drive gear for the intermediate gear box.this particular unit has the
bearing encapsulated with a wqter jacket...

I'll model something up more complete..

jeff