I was talking to someone about my Prius recently and he asked about the power split device. Lets say that I was driving at highway speed or cruising speed and I approach a down hill slope. I let off the gas and let the car coast. While coasting, the engine shuts down to conserve fuel. The electric motor may or may not be in motion while the engine is shut down. So, when the engine shuts down, does the rotation force of the power split device some how disengages from the engine so that the pistons are not in motion? otherwise you would create pressure from the pistons going up and down right? I hope I am making some sense. Does anyone know how the power split device works? I have a general idea but no concrete info. on how the device works when engine shuts down or when electric motor is shut down, etc...
Read Graham's Site first, then come back if you have any remaining questions. That site does a fantastic job of explaining the PSD. In short, you're somewhat right. The ICE cannot shut down completely beyond 41mph or MG1 will over rev (exceed 10k rpm) so the ICE keeps spinning to prevent just that situation.
this is one of the easiest way's to get your head around the PSD is to go to this website and push the slider buttons on the different sections and watch what happens to the different sections of the PSD http://homepage.mac.com/inachan/prius/planet_e.html
Also, this thread has some good pointers to "how the planetary gear works". I like Graham's site, but found that several of the other sites mentioned in this thread (particularly howitworks.com) eased me into the subject. After digesting these (and the animations, which I think are better), I felt up to tackling Graham's explanation.
Thanks guys...Graham's site is full of technical stuff and I am having a hard time digesting some of it...great site though. I will check the other sites out too...
