Introduction to Prius Power Flow

This is some interesting reading. When I think of CVT transmission, I am thinking of variable ratio pulleys, like those used on snowmobiles and other off road vehicles where the diameter of the two pulleys change to provide a constant engine speed while increasing the output shaft speed. Here the "gears" are fixed, and the three different motors are variable. Cool. I believe there is also less wear in this setup than the other type as there are no friction devices like a chain that will wear against the pulleys. As long as the chain doesn't stretch, and the fluid is kept clean, this setup should last a very long time.

 

<div class='quotetop'>QUOTE(MPG > HP @ Apr 1 2007, 05:58 PM) [snapback]416177[/snapback]</div>

There is a Piezoelectric Ceramic Gyro in the optional factory Navigation system. It is used primarily in parallel with the GPS location system to help display the vehicle in the navigation display on proper routes & turns. It is also used to track the vehicle when GPS signals are being blocked such as in tunnels & other places where the GPS signal is weak or non-existent.

There are also two inclination sensors in the combination meter assembly which are reportedly being used to help display proper fuel levels when parked or running along longitudinally or latitudinally sloped roadways.

It has been noted by some serious Prius 'hackers' that these inclinimometers are possibly feeding the main HV ECU information also as the distribution of torque requirements amongst MG1, MG2 & the ICE change noticeably on even slight inclines or declines while strong headwinds or tailwinds requiring equal amounts of torque have their requirements distributed or filled quite differently amongst the motive devices.

Best Regards,
Wayne – http://privatenrg.com

 

<div class='quotetop'>QUOTE(mwbueno @ Jul 24 2007, 05:07 PM) [snapback]484357[/snapback]</div>

Ooops,... After 80,000+ miles, I've got anemometer on the brain diseases... that should be 'inclinometer'

 

Everyone with a Prius should go to his website, and print his manual. I put one in the magazine pouch behind the driver's seat. I have a nice color laser printer with a duplexer at my dispense, and am thinking of printing copies for the hybridfest in Madison. However, I think I will need to print many more copies. It is one of the best, and most comprehensive writings on the Prius I have ever seen. It helped me out with my 2003, 2005, and 2006 model prii.

 

Very interesting. A little off subject perhaps but I've been reading Priuschat for months now and can't seem to get a straight answer on what seems to be a simple question... I think.
Q ... What are the mechanics of driving in neutral over 70 and beyon?
Can this cause any damage or premature wear?

 

If the engine is stopped then mg1 has to fully compensate for your ground speed. Risk is it explodes at 10,000 rpm?

search for nomograph to see the relationship. iirc, keep N speeds below 62 mph.

 

http://techno-fandom.org/~hobbit/cars/Nomograph-plus-PSD.gif
Above link to hobbit's page of the nomgraph.

 

A video is worth a thousand posts. For the mechanically inclined Prius enthusiasts. Long winded but hold out till he puts it all together. Even explains why reverse is always electric....

http://youtu.be/ZmHpSyTsfm0

 

With the engine stopped one of the electric motors has to spin to compensate. The higher the speed, the faster the motor must spin. At 70, it must spin very fast, much faster than the Prius normally allows.

Yes. This is why the computer doesn't normally allow the engine to be stopped above 45mph and part of the reason the manual tells you that you shouldn't coast in neutral.

 

having done a little auto trans work, i knew planetary gears had 2 speeds. one with ring gear freewheeling and another with ring locked with a band. i was wondering how a planet setup could be CVT. and i guess prius will not run with a dead or unhooked HV battery because you have no way to get "first" gear to pull out. or can 1 motor act as a generator to power other motor?

 

so, if you take the traction battery out of the car, can the car move? or is it totally immobile? my other question; what hooks and unhooks the ICE from the trans?

 

Yes and no. If you just take battery out of Prius it just won’t start. But transmission that Prius uses could work without battery if power is just send from MG1 to MG2 or the other way around.

Engine is always connected to transmission but if we don’t take any power or send any power to MG1 then MG1 can freewheel and so can engine. Or more accurately MG1 will be turning at speed related to speed of engine and speed of car but as long as we don’t send power to or take power from MG1 engine speed isnt related to car speed. If speed of the Prius gets to above 42MPH or 67km/h then we need to start spinning the engine because other vice MG1 is spinning too fast.

 

I have climbed a long steep grade "about 700ft getting steeper as you climb ending at 20% grade towing a 2240 lb caravan". The battery on the gen2 display showed zero bars, with the ICE working hard. I presume this would be 72% ICE to wheels 28% ICE to MG1->MG2-> wheels. Final speed was 20 mph. This is the only occasion I have seen the battery at this level.

John (Britprius)

 

Top gear is in line for the award of "the least factual TV program". They should win easily.
On a more serious note the Prius "although not the best tow car in the world" does tow surprisingly well. Further it still returns remarkable economy figures when towing. Returning 49.8 mpg (UK gallons) when driven within the UK towing speed limits.

John (Britprius)

 

I just wanted to make clear here for those unaware, the ICE (internal combustion engine) is not mechanically directly connected to the drive wheels. At no time does the ICE drive the car, it only assist the car in producing electric power turning MG1 (alternator). If you watch the video link that 9G-man posted at post 28, in the video at 13:45 its explained. A very well done video.