Hub motor with dual motor and planetary gear - CVT

[Jonca]

Hub motor with dual motor and planetary gear. Does such thing exist? If not, why not?
In automotive for example Toyota Prius is using planetary gear with ICE and electric motor forming Continuously Variable Transmission. And Revonte has developed an e-bike mid drive with the same idea using two e-motors. But I haven't found any hub motors like this.

I understand it could be difficult to fit two motors in hub. But since they would always be running high rpm they could be much smaller than in traditional hub with planetary gear? I was playing with the calculator and it seems that if the power output would be from the planet gear carrier (which could be challenging to put into practice I believe) and the motors on sun and ring gear. Both motors would have quite big reduction ratio to output.
I am not any e-motor expert so I am wondering if it is impossible to have two e-motors in close proximity due to magnetic fields effecting on each others.

 

[Balmorhea]

Planetary gears are inherently fixed ratio, not variable. CVT can be accomplished by different methods, but not gears.

SRAM Sparc was a low-powered 5-speed internally geared hub with 2 small motors inside.

 

[John in CR]

Planetary gears are inherently fixed ratio, not variable. CVT can be accomplished by different methods, but not gears.

SRAM Sparc was a low-powered 5-speed internally geared hub with 2 small motors inside.

Actually there was a guy on the forum 10-12 years ago that shared some info about exactly such a design, but all the info disappeared pretty quickly, probably to protect his intellectual property. The design may very well have ended up as the Revonte drive.

To answer the OP's question is 3 reasons it's not used in a hubmotor:
1. The design is almost surely patent protected.
2. The biggest limitation of hubmotors is heat dissipation, and it's a much greater limitation for geared hubbies since the heat pathway is so much longer and slower when in actual motors are enclosed in a sealed shell.
3. Electric motors have such a wide and flat torque curve that they don't really need transmissions of any kind unless the ebike is really a dual use vehicle (one for higher cruising speeds and the other going slow under big load).