Prime TMS (thermal management system)

As far as I know the only regen MG1 takes is from ICE not the wheels. MG1 role is to start the engine and maintain the right "gear" with carefully adjusting the amount of "regeneration".

I studied this animation for many hours to get it:
Toyota Prius - Power Split Device

If Prime really uses only one clutch, then it can only be to lock ICE so it can't move when MG1 tries to spin it. If it can't spin it, it spins MG2 (wheels). But this would also mean MG1 spins a lot faster and I question how much can it supplement at the top speed, IMO MG1 can help a lot at lower speeds, but max EV power must top out way before rated max EV speed.

Edit: Found the very same explanation from Toyota:
The Toyota Prius Prime is the way it is because people complained

"The one-way clutch allows the engine to lock and then the other motor can help boost the propulsion performance. That allows it to have more kilowatts going directly to the wheel. It goes from 37 kW [in the first-gen Prius Plug In] to 68."​

 

One thing to keep in mind is that MG1 in gen 4 spins 15% slower in EV driving since the final fixed gear ratio was reduced from around 3.2 to around 2.8 but that also means that MG1's torque contribution is not multiplied as much before reaching the wheels. Someone also claimed that MG1's max rpm was increased from about 9,500 in gen 3 to 13,500 in gen 4 but that seems higher than necessary and I haven't seen it personally in any Toyota document so I'm not sure if it's true.

 

Thanks Jeff! With this respect, also please read my comment on this article, which requests additional information on the quoted new electric motor, which is probably inaccurate.

The author replied he would cross-check the translation and his notes, but so far, no further news. I know being a journalist is not an easy job, but the author does not seem to have been reading many sources before writing his article...

Thanks from Europe for this interesting discussion, on technical aspects of this new transaxle which may harbor a couple of interesting innovations!

Jan

merged

Even if probably irrelevant, a small correction seems needed. It is 53 (MG2) + 23 (MG1) = 76 kW. This is what indicates the citation of the chief engineer is either mistaken, or the data provided even by Toyota are wrong.

Regardless, there is no need for a stronger MG2, if the battery limits the output to 68 kW.

Jan