The G3 CVT looks very clever to me!! I'm interested in a really good and detailed read on this that goes beyond pictures of spinning gears, mention of high torque and no slippage. Any ideas?? Thanks
I imagine that would be hard to come by unless you are collecting a paycheck from Toyota's engineering department. If you do happen to find something, please share though. As geeky as that sounds, I wouldn't mind reading up on it either.
I was fascinated when I did a web search on automatic transmissions and found a really good page with diagrams and animations. It appears to me that the Prius PSD is basically a 2-speed automatic transmission, with no reverse and with all of the hydraulic coupling (torque converter), etc, removed. Since the sun and ring are attached to electric motors instead of just locking-up, you get continuously-variable and reverse. Not highly technical, I know, but it explained things well enough for me. (If my observation is correct.)
Toyota's has put out some good tech into at TOYOTA: Company > Technology > Hybrid Transmission but I'd still be interested in any other good material that other people might know about.
I found this article which I thought was pretty good. Although I have no clue what happens under a cars hood - I found it interesting. Toyota Prius Hybrid Car E CVT Transmission Info
These are for Gen1 and Gen2. The same concept with slight difference in the speed of the electric motors. Understanding Contents Toyota Prius - Power Split Device A simulation of Prius's Planetary Gear
Only difference between Gen II and Gen III is the planetary reduction gear on MG2, where the planet carrier is locked. Otherwise, they function identically.
Thanks. everyone !!! The comments and source material that you provided will give me and others interested in this topic some great reading material. - g
And, Gen I is functionally identical to Gen II, except that the Gen I ring gear is overly complicated and is supported on numerous needle bearings, most of which were eliminated in Gen II when the ring gear was reduced from numerous smaller components to one major component. The Gen III MG2 rotates at about 2.5 times the rate of the Gen II and Gen I MG2, both of which rotate at 1.0 times, so the larger Gen III MG2 delivers about 2.5 times of its rated capacity to the wheels, compared to Gen I and Gen II, which deliver 1.0 times their rated capacities to the wheels. Nevertheless, Gen I and Gen II remain competent vehicles, when appropriately maintained, and when operated within their performance limitations.
I found these Youtube videos by WeberAuto to be interesting demonstrations on how MG1 and MG2 work to act like a CVT with the engine.
Download the publication at http://info.ornl.gov/sites/publications/files/Pub26762.pdf. It is an evaluation report on the Gen III Hybrid Synergy Drive done by the Oak Ridge National Laboratory. They did a tear-down of the HSD, then attached various components to their test equipment and measured performance under varying conditions.
