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

Jeff,   Well I still can't spell   The thing about the inconel coupling
concerns connecting two turbochargers in line mechanically with a gearbox. At
some point something gets connected to the hot side turbine and would be
exposed to the rotary exhaust temp. With your proposed design the compressor
sections are removed leaving the drive shafts available to connect to the
new slow down gearbox and nothing is hotter than the turbocharger bearing
housings.

george grimes