Designing a Planetary Gearbox to increase speed?

[IKE]

Originally Posted by kevin.li.rit

From Wikipedia



Does this make sense? Does a limited gear-ratio set on a ICE produce incomplete combustion?

Here is a link to some BSFC maps:
http://ecomodder.com/wiki/index.php/...on_(BSFC)_Maps
BSFC or Brake Specific fuel consumption shows how much fuel is consumed for each useable work unit produced at a given operating point.
If you look at the:
Mercedes Benz 300SD OM617 5 cylinder turbo diesel map,

You will see behaviour that Don R is talking about. where there is a sweet spot to run the engine from a (fuel in)/(work out). For that engine, the sweet spot is between about 1900 and 2600 rpm and the engine is about 60-90% fully loaded.
For gas and diesel engines, the general rule of thumb for peak efficiency is around 50% max rpm and at and above 50% load. This is a very general statement.

If you had a 1 speed gearbox, you would figure out the most important attribute,a nd size your gearbox to match that (acceleration, top speed, fuel economy). For Supermileage, we had a single speed drivetrain.

If you want it all, then you would go for a CVT or continuously variable transmission that would (in theory), give you the optimal ratio for whatever scenario you are driving. These gearboxes tend to have other issues (efficiency, cost, longevity, weight....).

The Toyota Hybrid system does a really good job of acting like a CVT without some of the draw-backs, and with some other benefits. Its not "perfect", but it is a really good system for a car, and a pretty neat one to figure out.

BTW, you can replace the generator/electric motor with Hydrualic pump/Hydrualic motor and achieve a similar set up... Of pressurized air... Or... Check out this Dana HVT. It is a 3 range IVT (infinitely variable transmission) powersplit...
http://www.youtube.com/watch?v=jsgw7ozlfJ0