The best analogy I can think of would be if you had an automatic transmission with one planetary gear set, and made the case of that transmission into an eclectic motor/generator. Add another electric motor around the driveshaft, between the "transmission" and the differential. Now you can drive the rear axle with just the electric motor around the driveshaft, or use the motor/generator "transmission" to allow the engine to add power to the driveshaft, and get the "CVT" control by using electronics to control the rotational speed of the motor generator "transmission". As you change the rotating speed of the "transmission" (or even change the direction of its spin) you can get CVT performance forward or reverse. -- Max Dillon Charleston SC '87 300TD '95 E300
On October 24, 2015 1:46:04 PM EDT, archer75--- via Mercedes <mercedes@okiebenz.com> wrote: > >Here is a unique transmission/driveline system that seems difficult to >explain. Following these links is an owners comment. Can anyone on the >list offer a better explanation of how it works? >Gerry > >https://www.youtube.com/watch?v=ZmHpSyTsfm0 > >https://www.youtube.com/watch?v=dLNDGUISTYM > >From another list: >> > My understanding is that all of the Prius generations have a >Constant Velocity Transmission or CVT. >> >> No. Toyota calls it an eCVT where CVT stands for Continuously >Variable Transmission, and "e" stands for electric. >> >> > While the 1 & 2 generations trans-axles have a chain that drives 2 >variable width pulleys, the 3rd generation model appears just to have >planetary gears and although some of the U-tube videos and Toyota ads >say that the transmission is CVT based; how does one change the gear >ratios continuously while using planetary gears? >> >> As already mentioned, "no variable pulleys". All planetary gears. >Prius Marketing calls the whole system "Hybrid Synergy Drive". Some >Lexus hybrids have added a 2 speed axle but I don't think that worked >very well. Its Lexus, they had to do something extra whether it helps >or not. >> >> What passes for a transmission in a Prius is also known as a PSD, >Power Split Device. Its a 3-input/output system where the torque and >RPM of any one depends on the other two. Each has its own ratio. The >sum of RPM * ratio equals zero, while at the same time the sum of the >torques must similarly be zero. Note that some RPMs and torques will >sometimes be negative. >> >> Toyota puts the engine (ICE) on one input, a small electric motor >(MG1) on another, then the front wheels and larger electric motor (MG2) >share the 3rd. Mostly the speed and torque on MG1 is varied to put the >ICE in the operating range needed to support whatever the driver is >demanding of the front wheels. >> >> Often MG1 operates as a generator while the ICE is running. Torque >reaches the front wheels via gears and electricity from MG1 powering >MG2. At highway speeds the gear path works best. At city speeds the >electrical path works best. But both are always in play all the time. >The simplicity makes a GM Volt drivetrain look like a Rube Goldberg >cartoon. > >_______________________________________ >http://www.okiebenz.com > >To search list archives http://www.okiebenz.com/archive/ > >To Unsubscribe or change delivery options go to: >http://mail.okiebenz.com/mailman/listinfo/mercedes_okiebenz.com _______________________________________ http://www.okiebenz.com To search list archives http://www.okiebenz.com/archive/ To Unsubscribe or change delivery options go to: http://mail.okiebenz.com/mailman/listinfo/mercedes_okiebenz.com
