Hybrid Car – More Fun with Less Gas

Jungle Motors Prius Plug In Kit - Page 2

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Posted by David T. Johnson on January 28, 2009, 6:39 pm
 
Elmo P. Shagnasty wrote:

Your understanding is wrong.  The gasoline motor on the current Prius
starts if the speed is above 42 mph but the electric motor also
continues to operate.  There is no physical limitation...it's just an
optimization programmed into the system by Toyota based on the current
battery and motor capacity.  Similarly, the gasoline motor never runs
below 1,000 rpm not because of any physical limitation (the motor would
run just fine at 500 rpm) but because it's an optimization.  The whole
point of the system is to maximum efficiency.

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

Posted by greenpjs on January 28, 2009, 7:46 pm
 
On Wed, 28 Jan 2009 10:39:39 -0800, "David T. Johnson"


A previous poster explained that the electric motor runs faster if it
is the only provider of power.  If that is true, and it sounds
plausible to me, it means the 42 mph limit only would apply if the ICE
is NOT running.

Posted by David T. Johnson on January 28, 2009, 9:43 pm
 greenpjs@neo.rr.com wrote:

Then the previous poster was also wrong.  The electric motor/generator 2
  (MG2) rotor is ALWAYS turning when the car is moving and it's speed is
proportional to the speed of the vehicle.  It does NOT change its speed
if the gasoline motor is not running although it might put more current
through its stator coils.  Here's a link to a diagram that illustrates this:

http://www.cleangreencar.co.nz/page/prius-technical-info

The blue-green-red device in the center is the planetary gear system (I
posted a link to an interesting flash simulation of that in another
message in this thread) and the 'red' outer ring is directly connected
to the MG2 rotor.  There is no '42 mph speed limit'.  The gasoline motor
(ICE) always starts when the speed is above 42 mph but the electric
motor (MG2) continues to operate as well.  That is just an optimization
programmed into the system and is NOT a 'speed limit' on the electric
motor.

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

Posted by Tomes on January 28, 2009, 10:41 pm
 "David T. Johnson" ...

OK here is what I am not clear on.  I can get my Prius to run on electric
only for periods of time at any speed [according to the monitor screen
graphics] by lifting my foot up and then placing it lightly down.  I can
make this happen for quite some time if I am on a slight down slope and
mileage soars at that time.  I do not understand why they put this 42 MPH
ICE startup thingy in there at all.  If it only used the electric
propulsion, I am thinking that it ought to be fine through that number.  I
do not believe that it has anything to do with electric engine RPM as the
CVT would just ratio that problem away.  When I am on a slightly down slope
I can and have used electrics up to 42, had the ICE come on [annoyingly to
me ;-}], did the foot thing to instantly turn it off again and then continue
to gain speed to over 50 MPH.  There is one road that I use sometimes that
does not have traffic so I can granny it along without issue and I do this
for real.

What am I missing here?

Perhaps this is a joke from a Douglas Adams reading Toyota engineer in Japan
who deftly worked it all the way through the development process and got it
into the car?
Tomes


Posted by David T. Johnson on January 29, 2009, 2:27 am
 Tomes wrote:

 From the simulation, it looks like the MG1 generator will overspeed
above its 6500 rpm max if the vehicle speed is above  42 mph and the red
engine crankshaft doesn't start turning so perhaps that is the 'speed
limit' that requires the gas engine to start up above 42 mph.  As Mr. G
pointed out, the MG1 could be used to turn the gas engine crankshaft but
more likely is that Jungle Motors is electric-only below 42 mph but not
above  that speed.
--
Posted with OS/2 Warp 4.52
and Sea Monkey 1.5a

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