Ford, Prius, Volt Transaxle Disassembled and Explained

WOW, lots to digest. Thanks for posting.

 

Every one of John Kelly's videos that I've watched has been nothing short of excellent. I usually link to his video on the P112 to show how Toyota's hybrid gearboxes work.

It's worth noting that the Toyota P610 actually has a slight simplification as compared to the Aisin/Ford gearboxes that John shows. You'll notice that MG2 and the power split device are geared to separate gears on the intermediate shaft, whereas the P610 uses the same intermediate shaft gear for both MG2 and the PSD. That'll save some weight, although at the expense of some gearing flexibility (the PSD to intermediate shaft and MG2 to intermediate shaft gear ratios are related, whereas in the Ford gearbox, they're not necessarily).

 

It's not clear to me what transaxle is built into which prius. In what Prius do I find the Chevrolet Volt 4ET50 Transaxle?

By the way: Weberauto was my main source of information for making my own video. Great source.

 

It's interesting to compare all of the designs, though, for electronic simulations of CVTs - the two main Toyota designs, the Ford design that Toyota's now using, and the GM designs.

The Ford video describes very similar designs to the Gen 4 Prius gearbox.

 

did gm license their transaxle to toyota?

 

I read this in the description:

This video shows the components, similarities, and differences of the three generations of Ford's hybrid transaxles from 2005-2016.
This transaxle design is also used by the 2016 and above Toyota 4th generation Prius with the P610 transaxle as well as the new 2017 Chrysler Pacifica Plug-In Hybrid with the SI-EVT transaxle.

So, is the 4th generation Prius similar to the first, second or third generation Ford? Is the Prius P610 exactly the same implementation, or just the same overall design? What are the differences?

I ask because of my own video, in which I made a real effort to get my facts straight:
Prius Hybrid Drive Explained | PriusChat

I failed in explaining the exact implementation 3rd and 4th generation. So that's why I ask: Does your video describe the exact built of the 4th generation prius, with every cogwheel, tooth and chain in place, or just a ford-driveline that's more or less similar?

 

agreed, that wording is confusing, and makes it sound like prius is getting something from ford, not gm.

 

Thanks. That clears up a lot.

 

"Ford’s decision to bring development of a new continuously variable transmission for its line of plug-in hybrid and hybrid vehicles in house wasn’t due to dissatisfaction with Aisin, the Japanese supplier that provided previous-generation hybrid CVTs.

Rather, Ford engineers thought they could make an even better transmission while cutting costs.

The new Ford-developed HF35 transmission, like the Aisin-sourced unit, is an electrified CVT. But it outperforms its predecessor in several key areas, says Shailesh Kozarekar, manager-transmission electronics."

Ford Says Homegrown CVT Key to Speed, Fuel Economy of New Hybrids | Technology content from WardsAuto

 

The Prius's P610 is a similar layout, but tooth counts are all different, the inverter mounting is closer to the earlier Ford generations (as that video actually does explain), and where the intermediate shaft in the Ford gearboxes uses a separate gear for MG2 and the power split device itself, the P610 gears MG2 and the power split device to the same gear (so there's only two gears on the P610's intermediate shaft, where the Ford has three - and that video missed that).

I suspect that a more in-depth analysis of what's different would require actually physically tearing down a P610 to compare, and they apparently didn't have one to do that to.

 

The one way clutch shown for the Gen 1 Ford is on the sun gear-generator shaft while the one for the prime it is on the planets carrier-engine shaft.
We know that with the Prime, the purpose is to allow dual motors drive in EV, but with G1 Ford we do not know to what purpose?

 

Don't forget about traction-control. There needs to be a means of disengaging. How is that achieved for each of the systems?

 

That wouldn't necessarily be in the mechanical domain, though, it could be on the control side. Just reduce power going to MG2, and command a reduction in fueling on the ICE.

 

The video demonstrates how amazingly compact and lightweight the planetary gearset is compared to the 'conventional' helical step gears for same torque rating.
While in helical gears the full load is carried by only one tooth at a time, in a planetary set (4 planets as we have here) the load is simultaneously carried by 4 teeth in each component of the set.
So each tooth load carrying capacity is 1/4 of the full load and can be much smaller (width and length) making the 'gear wheel' much smaller as well.