GOBAO ECVT EMTB Mid-Drive Motor

[Astro66]

Some clever freewheeling/clutch mechanism so Motor B can disengage when not actively shifting

I assume you are talking about the motor connected to the Sun Gear, which is MG1. It cannot disconnect or freewheel, or you'll immediately go into the lowest gear. Also, in the lower gears it is being driven backwards by the plantetary gears, so you'll lose all the regenerative energy.

And don't forget. When the Sun Gear is being driven FWD by MG1, that energy isn't just changing gear ratio. It is also a parallel power source to MG2. So both motors are driving the wheels.

Without one of those, I'd expect noticeably worse range than a comparable single motor mid drive.

I do expect losses to be slightly greater than a derailleur setup. But it will be marginal. ECVTs can be designed quite efficient. But as the technology improves. They will be able to introduce regenerative braking, and I'm guessing a 10-15% improvement in range. Which will far exceed any minor losses.

the e-CVT is doing ratio changes all the time.

It doesn't have to do ratio changes. It can be programmed to give a constant ratio. In this mode MG1 is constantly adjusted to the correct speed and direction to give a fixed cranks to wheel ratio. Depending on how well the software responds, it will feel just like a fixed speed gear.

 

[Ndanger]

I assume you are talking about the motor connected to the Sun Gear, which is MG1. It cannot disconnect or freewheel, or you'll immediately go into the lowest gear.

The control motor. Which if able to be mechanically locked (no longer a variable ratio transmission) would free up the control motor from needing to generate holding torque, and gaining electrical efficiency.

In some e-CVT designs, the control motor doesn't need to draw power continuously if the planetary gear set can be mechanically locked or if there's a one-way clutch. But in a true e-CVT where the ratio is actively controlled, it requires the second control motor to maintain position against torque.

When the control motor, we will call it Motor B is "electrically locked" to hold a gear ratio, it's basically acting like a brake, burning current to create holding torque without doing useful work. That's the worst operating point for an electric motor (high current, near-zero RPM, lots of heat, minimal efficiency). Even when you're just cruising steady, that control motor is using watts to maintain position against the planetary forces, and yeah, during acceleration and climbing when the ratio is actively changing, Motor B is spinning up and down, which means it's spending a lot of time in those inefficient transient zones of the motor curve.

As far as efficiency curves for the motors, here are some numbers:
Motor A at optimal RPM might be 85-90% efficient
Motor A at suboptimal RPM might be 70-80% efficient
Motor B holding position might draw 50-100W continuously

 

[slickrock]

For trail riding , constant minor accelerations, short climbs, coasting, braking, the e-CVT is doing ratio changes all the time. Motor B is never settling into a nice efficient cruise. Compare that to a mechanical mid drive where, yeah, you might be in a slightly sub optimal gear sometimes, but there's no parasitic motor burning watts just to hold position.

MG1 holding your position is actually energy capture - MG1 isn't just driving that counter-torque in to a resistive load, it's being used to either charge the battery or power MG2. There is conversion loss in transferring torque->generator->inverter->motor, but as mentioned, there are offsetting efficiencies. Like always running in an ideal power/efficiency delivery curve, keeping the motor at the optimal RPM and you at your best effective cadence. What is lossy is an MGU, constantly shifting a bunch of carriages and spur gears creating many more mechanical friction points.

A much bigger battery to mask the losses, or
Some clever freewheeling/clutch mechanism so Motor B can disengage when not actively shifting
...

There are two clutch mechanisms, but not for the MG1/Sun gear. Outside of a battery regen mode, there would be no reason for MG1 to be running at all when coasting any more than your ebike motor runs when your not pedalling. As soon as you apply torque at the pedals, the ECVT springs both MG1 and MG2 to life electromotively- all gear transfer systems are fixed and ratios dynamically set in a hundredth of a second.

 

[sethimus]

Looks like a case of the pot calling the kettle black!

you can see your importance in the availability of avinox bikes in your country...

amflow, late. teewing, late. is velduro now available? afaik also a no. so yes, not important, else someone would hurry the fuck up to sell them there if they'd see it as a viable market that doesn't need a big sales network first to serve the few customers in a very huge land mass.