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Added Cruise Control to New Prius! - Page 5

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Posted by David T. Johnson on May 5, 2009, 12:11 am
Tom Cole wrote:

I'm not sure what you're claiming is not correct.  Here's a description
of the operation of the Prius.


MG2 has to be rotating or the front wheels are not rotating.  However,
the front wheels CAN still be rotating if the gasoline engine is
stopped.  That's why I said the Prius is more of an electric drive with
a gas-engine assist.  The gasoline engine can still provide power to the
front wheels through the pinion gears, but only if MG2 is operating.  If
MG2 is not rotating, the gasoline engine will turn MG1 but the front
road wheels will not turn.  There's no similarity to a diesel-electric
locomotive.  The simulation on this page will help you to understand the
relationship between MG1, MG2, and the gasoline engine.


Posted with OS/2 Warp 4.52
and Sea Monkey 1.5a

Posted by Tom Cole on May 5, 2009, 4:23 am
On Mon, 04 May 2009 17:11:19 -0700, "David T. Johnson"

I am aware of these two sites.

The problem may be one of over-simplification. Yes, MG2 is directly
connected to the wheels and must rotate when they do. However the wheels
are also directly connected to the Power Split Device (PSD). Therefore
when the wheels are rotating the MG1 and/or the ICE must also rotate.
Your explanation implied that it was only the MG2 that drove the wheels.
Not so. MG2 may be driving the wheels, or being driven by the wheels (as
a generator) or may be free-wheeling.  Independently, under the control
of the computer, power may be supplied from the MG1/ICE combination via
the PSD.

The only time the MG2 is solely in control is when reversing, although,
even then I have experienced the ICE starting when extreme reversing
power is needed (e.g. to get a stopped front wheel over an obstruction
such as the kerb).

Posted by David T. Johnson on May 5, 2009, 7:46 am
 Tom Cole wrote:

No, it didn't.  Electric drive with a gas-engine assist.  (I have no
idea why that is upsetting to people here.)  The gasoline engine could
not 'assist' if it wasn't also able to supply power to the wheels.
When you push the 'accelerator' pedal down, the computer first puts
current through the MG2 windings and then uses MG1 to start the ICE
turning if more power to the wheels is needed as the speed increases
and/or if the battery needs charging.  The throttle for the Prius
gasoline engine (ICE) is always controlled by the computer which also
monitors the road speed so the cruise control elements are already
included on every Prius.

No, the ICE is completely unable to supply power to the wheels when
reversing because the ICE, like all gasoline engines and unlike MG2,
only rotates in one direction...and there is no 'reverse' gearbox on a
Prius.    The ICE is only charging the battery if it is running while
you are reversing so in reverse, the Prius is electric drive only.

Posted with OS/2 Warp 4.52
and Sea Monkey 1.5a

Posted by Elmo P. Shagnasty on May 5, 2009, 10:50 am

Because it's not true?  Is that a good enough reason?

Because people just ignore reality and make up their own "facts" as it
suits them, and then spew those "facts" to the world?

You WANT it to be "an electric car", but it's not.  Suck it up and deal
with it.

Posted by Tom Cole on May 7, 2009, 12:05 am
 On Mon, 04 May 2009 23:46:58 -0800, "David T. Johnson"

I agree that it seems illogical that the ICE should be needed when
reversing under full power, yet the ICE *does* start under these
conditions on my 05 Prius and also on my wife's 03 Prius, even when they
are in EV mode. We reverse into our garages and if the approach is
misjudged such that the front wheels are stopped at the kerb, applying
full accelerator to get over the steep bump will cause the car to come
out of EV mode and the ICE to start.

I have also experienced this when reversing up steep driveways in EV

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