Douglas Fir wrote:

Paul

Check out this URL on how Scandia did turbo compounding. The graphics are
identical to Caterpillar.

http://www.westwardscania.com/trucks/NTR/technology/turbocompound/how_does_
it_work.asp?ComponentID=43343&SourcePageID=56704#2>

What is interesting is that the second turbo runs up to only 55,000. It
appears there are basically only two sets of step down helical gears at  5:1
ratios. There is a hydraulic coupler which has within, I can imagine, some
spinning discs in oil.  Vary the gap or bypass pressure and hence control
friction between the plates and the slippage. Sounds a little bit like the
torque converter in an automatic transmission.  Much easier to deal with
than a CVT.  Might be able to use MOBIL 1 as well:)

For a 2 rotor compounding 20 to 30 Hp back is starting to look
sexy.   270+ HP with two rotor. P-ports are starting to look more attractive
as well because they breath so well.  The inefficiencies of complete
combustion are more than made up for by the robust exhaust and ability to
devote the turbo exclusively to turbo compounding.

A wastegate might be needed at idle or when starting though.

Doug in Japan

 
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