> ....Snip.....
>
>
> Gordon, Paul et all
>
> Every six months I check back in to see what Catapillar Inc. is
> doing with
> their mechanical as well as electric turbo compounding schemes. If
> you do a
> Google search for "Caterpillar turbo compound turbine" you will find
> several interesting PDF files there.
>
> The first one you can skim through it. It is titled
> "Diesel Engine Waste Heat Recovery Utilizing Electric
Turbocompound" ...
> This report has some clear pictures and gives an understanding of
> what it
> takes to perform this task. As much as we may love the concept
this PDF
> will give a clear indication of the sizes and technology involved to
> pull it
> off or for us not:) To heavy for flight, even if it is scaled down
> to our
> rotary. Switched reluctance generators are also very challenging to
> develop.
>
>
> The second PDF I recommend looking at is called "Engine System
> Approach to
> Exhaust Energy Recovery". There are some little tibits of
> information that
> are real jewels, hints perhaps for our use. I'll let you read it
> first and
> then we can discuss it.
>
>
> In another PDF report I found the statement that Garrett was the only
> company that had successfully manufactured a turbo compound system.
> Hmmmm???? I don't think so.
>
>
> Best Regards
>
>
> Doug Fir
>
>
> "Engine System Approach to Exhaust Energy Recovery"
> Hard to fathom this stuff as it is power point presentations
> with little or no text explanation. Probably puts everybody
> to sleep that watches it :)
> What is the base line engine power and BSFC?
> IMHO the TC stuff is marginally cost effective
> as they are starting with a cool exhaust diesel.
> I wonder if it will actually go into production.
>
> Paul Lamar ...No rotor no motor.
>
>
> Doug,
>
> That Caterpillar stuff is excellent.
>
> Although the generator is not of use to us, as you said, the layout
> is exactly what I had in mind. That stretched shaft for the turbine
> and compressor will let us put the traction drive in the middle,
> instead of the generator.
>
> This is the most efficient layout, because you don't have a separate
> drive for the supercharger. I love the fact that they have pictures
> of that turbine shaft. I had been wondering how much beefier it
> needed to be in the middle to resist twisting -- and mindful that
> you can't have the diameter too big because of the high rotational
> speeds and bearing limitations.
>
> Now I see that this is workable. Excellent. All you need to do to
> make a turbocompound engine is get a turbocharger, dissasemble it,
> machine a new long shaft and put the traction drive in the middle.
> Of course you would probably have to make your own traction drive in
> order to fit the dimensions of the shaft, but Paul is making one
> anyway so his design could be modified.
>
> Of course, you would have your CVT belt going from the turbine to
> the traction drive to the engine shaft.
>
> Btw, snowmobiles use belt CVTs too and they go upwards of 100 hp, so
> if the scooter CVT can't handle the power -- and it's looking like
> that will be the case, just go to the snowmobile drive.
>
> Also interesting to see the pressure ratios on the Cat turbine and
> compressor. Notice the compressor pressure ratio of 3 : 1. Like I
> have been saying, in order to recover power you need a high pressure
> ratio on the intake side.
>
> Also interesting that the turbine is 3.7 : 1, or about 25 percent
> higher than the intake side. This is something to keep in mind when
> matching compressor and turbine.
>
>
> Regards,
>
> Gordon.
>
> I did some R&D on scooter drives when I was over in Rome Italy a year
> ago.
>
> Proprietor
>
> Paul Lamar ...No rotor no motor.
Gordon,
I thought you would catch the significance of the backpressure
statement.
Good advice on the snow mobile units. The belt that the local Honda
dealer
gave me is way too long to use. Perhaps the snowmobile drive belt is
shorter
or I would have to have one specially made.
Now about putting a traction drive between the turbine and the
compressor
'no kapito. The supercharger traction drive increases the speed ratio on
the compressor by 7.5:1 while to feed the e-shaft power side we need to
decrease it by that much and more.
Doug Fir
Doug,
My idea for putting the traction drive between the turbine and
compressor is not going to work with your Rotrex drive.
What I'm envisaging is exactly what you see on the Cat setup. That
long shaft is common to both the turbine and compressor, so they
both spin at the same speed, just as they would in a turbocharger.
Now what I want to do is put a traction drive in the middle, instead
of that generator. That middle part of the shaft will be captured by
the planet rollers, which, in turn, will act against the ring gear,
from which the belt will take off.
This will require a custom traction drive. I know, I know...it's
much easier to just get a Rotrex. However, you now need a separate
drive to the engine to drive the compressor. With my idea, you just
have one belt.
It will also give the compressor the benefit of the CVT because as
the turbine spins faster (as it will at high altitude, due to the
higher turbine pressure ratio resulting from lower ambient
pressure), the compressor will also spin faster. This is exactly
where you need extra boost because as ambient pressure drops you
need your compressor to spin faster to make a higher pressure ratio
and keep your manifold pressure up.
If you size the turbine, compressor, gear reduction and CVT properly
you can have a hands-off system to manage boost as you climb. And as
you go higher, the excess power from the turbine will increase and
your fuel specifics will go down.
Regards,
Gordon.
The Rotary Engine NewsLetter. Powered by Linux.
ACRE NL web site.
http://www.rotaryeng.net
Copyright 1998-2006 All world wide rights reserved.