Finland's Verge Motorcycles, maker of an advanced electric motorcycle, has spun off a company called Donut Lab, which is making hub motors for electric vehicles.
The Finland-based company’s in-wheel motor serves up 650 kilowatts of power
Can anyone explain the benefit? I would’ve thought putting the motor in the wheel would subject it to way more wear and tear from being only a tire wall’s support away from every pothole and bump in the road. Mounting a motor on the vehicle frame and using a driveshaft offers much more protection.
The benefit is driveline efficiency- by eliminating all gears/CV joints/axles and only having one or two bearing races rotating, you reduce driveline friction losses and “wasted” rotational inertia to effectively null. With electric vehicles every single watt per mile matters, even shaving 0.1% off helps bunches. It also reduces part count, and thus cost too.
Per wheel motor drives also allows significantly more advanced torque vector traction control.
The downside is just what you say, mechanical isolation- the motor is now in a dirtier, harsher environment, the power cables must now flex continuously with the suspension and will be a very high risk failure point, and the outboard wheel now has a significantly higher unsprung mass meaning the suspension will need to be beefier and be less effective at dampening road vibrations to the rest of the vehicle.
Yes, it’s a stupid idea, and there’s a reason why almost nobody does this. Mostly because of the handling, the more unsprung mass you have, the harder it is to keep the wheels on the ground.
This invention surfaces every five years or so. Obviously never goes anywhere. I bet the creators are well aware of this and they just want to bait a dumb enough VC to exit with a load of cash.
Can anyone explain the benefit? I would’ve thought putting the motor in the wheel would subject it to way more wear and tear from being only a tire wall’s support away from every pothole and bump in the road. Mounting a motor on the vehicle frame and using a driveshaft offers much more protection.
The benefit is driveline efficiency- by eliminating all gears/CV joints/axles and only having one or two bearing races rotating, you reduce driveline friction losses and “wasted” rotational inertia to effectively null. With electric vehicles every single watt per mile matters, even shaving 0.1% off helps bunches. It also reduces part count, and thus cost too.
Per wheel motor drives also allows significantly more advanced torque vector traction control.
The downside is just what you say, mechanical isolation- the motor is now in a dirtier, harsher environment, the power cables must now flex continuously with the suspension and will be a very high risk failure point, and the outboard wheel now has a significantly higher unsprung mass meaning the suspension will need to be beefier and be less effective at dampening road vibrations to the rest of the vehicle.
Yes, it’s a stupid idea, and there’s a reason why almost nobody does this. Mostly because of the handling, the more unsprung mass you have, the harder it is to keep the wheels on the ground.
This invention surfaces every five years or so. Obviously never goes anywhere. I bet the creators are well aware of this and they just want to bait a dumb enough VC to exit with a load of cash.
Not just that, I doubt the motor would be particularly happy with all the vibrations happening to it.
Definitely not. There’s a few aftermarket conversions that use hub motors, but the ones I’ve seen were on vehicles like Land Rovers with live axles.
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