"PC Paul" wrote in message
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"Doctor Evil" wrote in message
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"Andy Luckman (AJL Electronics)" wrote in message
. ..
In article , Dave Plowman (News)
wrote:

The latest Prius is an amazing success. It doesn't have a gearbox,
just
one plaetary gear assembly.

Whereas a gearbox is what?

Shifting ratios between cogs. The Prius doesn't do this or have a CVT
which
has pullies and a belt. Just a simple assemmbly.

It has no mechanical transmission. No mechanism to shift gears or wind
pullies in and out. It is very simple. You need to look more and
understand
how a planetary system works. There is no ratio selection. It is simpler
than a normal car. No complex power sapping transmission, juts a
planetary
gear assembly, which
just turns, as do bearings. The "complexity" is people not
understanding
it.


OK, Thanks for the suggestion, I know it all now. Interesting. G

The Prius planetary gear works like a flattened out differential where the
two 'halfshafts' are driven by the petrol engine and the electric motor
driving the wheels, and the 'driveshaft' takes power to the generator.

So by varying the relative speeds of the petrol engine (by throttle) and
electric motor (by speed controller) you can get almost any ratio you like
from reverse to full ahead, and any power split between wheels and
generator... Nice.

Very clever. Very elegant. Very simple. The Toyota is different to the
Honda. The planetary transmission arrangement means that the engine can be
assisting the electric motor direct to drive and, charging and powering the
electric motor - all at the same time. Or be 100% on the engine or 100% on
the electric motor. The Toyota transmission is far ahead of all others. So
much so, they nearly have all licensed it for their own vehicles: Ford,
Honda, etc.

Toyota have eliminated stepped gears and pullies in the transmission. Think
of the engine as always in top gear (most efficient, and the Prius engine is
designed for high economy, tuned to a semi Atkinson) and when the speed
drops (dropping down the gears) the electric motor comes in to fill the gap
of gears - two power sources. Quite simple and neat - an electric
transmission. The electric motor can also power the vehicle by itself. The
transmission is very smooth because one really isn't there. BTW, the new
Prius is quite different to the Mk 1.

The batteries can only give 2 to 4 miles then they run down and the engine
comes to assist and recharge. A company in California has fitted Lithium
Ion batteries that give 60 miles range. Unlike the standard Prius, they fit
an electric socket for overnight charging. So, commuting, you may never
ever go onto the engine. Except in winter for heating the car. The car
then averages 135mpg.

A lot of people tank total ******** about the Prius, due to total ignorance:
complex, breaks down every week, batteries need replacing every few years,
only does 21mpg, and other such garbage.

New battery technology will make an impact that is for certain. Lith Ion
andLith poly batteries will give much longer range, to the point the all
electric car is not that far away. Toshiba have introduced a few months
back, a battery that can take a high charge very quickly, so most, if not
all, the energy clawed back on brake regen will be stored in the battery.
These are a few years off. Toyota also have a one year testing of batteries
before accpeting the type. Panasonic can't make enough of them. So, things
look like changing....or if Bush and his oil cronies have their way, they
will not.

Try here for a simulation
http://homepage.mac.com/inachan/prius/planet_e.html or here for a nice
explanation in diff terms
http://home.earthlink.net/~graham1/MyToyotaPrius/SideBars/PsdLikeDiff.htm

I was going to post those.