[RSnyder]

Thanks to [email protected] for finding this Ford document describing their hybrid design and diagnostics.

So the basic topology of the power split is the same as Toyota. But they don't connect "MG2" aka "Traction Motor" directly to the ring, it has its own separate geared connection to the drive train. I kinda like this because it allows for physical separation of the parts (they can be replaced separately), and it allows the RPM range of the two motor/generators to be independently selected to best engineering design.

They don't drive the rear wheels directly with a third electric motor as the Highlander Hybrid does. Instead they use a traditional transfer case. I prefer the reliability and better (computer managed) control of torque with the third motor. But the Ford design is probably cheaper.

So nothing radically new and different. I wonder why they made this information so hard to find.

 

[DanMan32]

Seems the same to me. Both the Toyota and the Ford have MG2 physically mounted to the transaxle. Only difference is the gear ratio. in the Prius, MG2 would have to spin at a faster RPM to acchieve the same power to the wheels, where in the Ford, it would spin slower, but need more torque for the same power output to the wheels.

I noticed they disclosed the negative power split mode, Which Graham and others figured out the Prius does also. Emulates overdrive. The Ford paper describes the power modes in better detail and accuracy. I noticed this when it stated that MG2 acts as a motor or a generator to achieve final power output in relation to what the ICE/PSD is delivering.

 

[stevewa]

They don't drive the rear wheels directly with a third electric motor as the Highlander Hybrid does. Instead they use a traditional transfer case. I prefer the reliability and better (computer managed) control of torque with the third motor. But the Ford design is probably cheaper.

I suspect it's not a question of cheaper, but rather parts commonality with the conventional Escape. By reducing the number of hybrid-unique parts (didn't have to design a custom rear suspension to handle the seperate electric motor) they were able to trim the amount of additional manufacturing, testing, etc that has to be done. The downside is the extra weight of that big driveshaft going to the rear that is eliminated in the HLH/RX400h design.

The torque transfer is still computer controlled front-to-back, and can be varied from zero to 50 percent distribution.