UK-based YASA has just built a tiny electric motor that makes Tesla motors look like slackers, and this invention could potentially reshape the future of EVs
This looks small enough to be installed within the wheel hub itself. Imagine a car with four motors, one inside each wheel. The entire floor pan could just be one thin battery, and everything above it could be passenger and storage space.
And some 2000s EVs tried it. But it’s impractical.
It increases unsprung weight, e.g. weight not cushioned by suspension. Bad for ride/handling/steering feel.
All that vibration is HARD on the motor. Read: unreliable.
Motor is more exposed to temperature/dust. Again, reliability.
In reality, a decent suspension needs a lot of room under the body anyway. An axle to get the motor in the body is dirt cheap on the rear, and still pretty cheap on the front, and you could just mount this thing sideways to make it flat…
Handling and ride quality are dramatically and negatively impacted by every bit of weight that is not held up by the suspension. That’s why higher performance cars will have lightweight wheels. Rather than steel wheels you see on lower performance cars.
It’s better to just put all the heavy drive components inboard on the chassis and run drive shafts to the wheels.
You see motors in the hubs of bicycles, because they really don’t go that fast. So even if the bike has a suspension, it’s not that big of a deal. Motorcycles on the other hand would need to keep any heavy parts inboard.
Steel wheels haven’t been common on anything but really cheap cars for a few decades now, but in general your point holds true. There’s heavier and lighter alloy wheels out there.
Still, these could be just tiny motors connected to the wheels via a short shaft on the rear especially. Instead of the huge monstrosities most EVs currently seem to use which are huge, as they also include gearing and such. Still leaves more space for battery without having to go unsprung with hub motors.
One issue I hadn’t thought of is putting traditional brakes (which generate a ton of heat) right next to the motors. Again, we’re just asking for mechanical issues here, and we’re ballooning unsprung mass to mitigate it, especially in heavier cars that take a lot to stop.
The entire floor pan could just be one thin battery, and everything above it could be passenger and storage space.
This seems like a minor thing, but the control electronics for the motors takes up a nontrivial amount of space. So do “traditional” subsystems like hydraulics, climate control, or an old fashioned car battery (which often exists in parallel to the EV drivetrain).
Theres also safety to consider. A traditional sedan “hood,” even a small one, is easier on standing pedestrians, so it hits their legs and they flop on top, instead of slamming them like a wall (as a bus-like front would).
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Sounds very limited market.
Those are golf cart and scooter motors, not suitable for highways
BMW currently uses brushed motors in their EVs so I’m not looking to them for any advice. Maybe BMW wants their traditional central layout CM450 tech. But! DeepDrive is the first hub motor I’ve seen that did not need gearing, so that is actually cool. I think they’ll be relegated to rear wheels due to scrub radius limitations but that could be ok.
They make sense for scooters, bikes, and other low speed or two wheel personal transport. For anything with an actual suspension (designed for a highway) there is just too much competition for space with brakes and suspension linkage. The unsprung weight, exposed high voltage cabling subject to road debris and accidents are problems too. And what to do hub motors really gain you?
Simplicity, no transmission. As to unsprung weight, designs like these have a ridiculous power density, so add only very little. Advanced suspensions are active anyway, so just part of the wheel robot.
They might work in the rear if used instead of rear brakes. Rears do far less work anyway and brakes are heavy. Powerful electric motors can do a lot of regen, similarly assisting the front brakes.
I’ve had near 8 kilogram rear brake disks on a diesel wagon, not even a performance car that would require huge brakes, current car is 5. Calipers weigh a bunch too. Pads themselves are light, but still add to the whole setup.
Except for the fact that that much power would need massive batteries. So your thin small battery would be dead the first time you mashed the peddle to the floor
This looks small enough to be installed within the wheel hub itself. Imagine a car with four motors, one inside each wheel. The entire floor pan could just be one thin battery, and everything above it could be passenger and storage space.
That’s how EVs started! Sorta.
This is from a Porsche in 1900:
And some 2000s EVs tried it. But it’s impractical.
It increases unsprung weight, e.g. weight not cushioned by suspension. Bad for ride/handling/steering feel.
All that vibration is HARD on the motor. Read: unreliable.
Motor is more exposed to temperature/dust. Again, reliability.
In reality, a decent suspension needs a lot of room under the body anyway. An axle to get the motor in the body is dirt cheap on the rear, and still pretty cheap on the front, and you could just mount this thing sideways to make it flat…
That would be a lot of unsprung weight.
Handling and ride quality are dramatically and negatively impacted by every bit of weight that is not held up by the suspension. That’s why higher performance cars will have lightweight wheels. Rather than steel wheels you see on lower performance cars.
It’s better to just put all the heavy drive components inboard on the chassis and run drive shafts to the wheels.
You see motors in the hubs of bicycles, because they really don’t go that fast. So even if the bike has a suspension, it’s not that big of a deal. Motorcycles on the other hand would need to keep any heavy parts inboard.
Steel wheels haven’t been common on anything but really cheap cars for a few decades now, but in general your point holds true. There’s heavier and lighter alloy wheels out there.
Still, these could be just tiny motors connected to the wheels via a short shaft on the rear especially. Instead of the huge monstrosities most EVs currently seem to use which are huge, as they also include gearing and such. Still leaves more space for battery without having to go unsprung with hub motors.
PS
One issue I hadn’t thought of is putting traditional brakes (which generate a ton of heat) right next to the motors. Again, we’re just asking for mechanical issues here, and we’re ballooning unsprung mass to mitigate it, especially in heavier cars that take a lot to stop.
This seems like a minor thing, but the control electronics for the motors takes up a nontrivial amount of space. So do “traditional” subsystems like hydraulics, climate control, or an old fashioned car battery (which often exists in parallel to the EV drivetrain).
Theres also safety to consider. A traditional sedan “hood,” even a small one, is easier on standing pedestrians, so it hits their legs and they flop on top, instead of slamming them like a wall (as a bus-like front would).
Aptera wanted to do this with their flagship Solar Electric Vehicle (SEV).
IIRC, they switched to an outwheel motor because of the weight the inwheel motors added to the wheels. Could be wrong tho
LOL. Coming soon…since 2009
For real lmao
Waiting for the zeta pre-production ‘final-final-REALLY-FINAL’ build
Hub motors are a party trick. They will never reach mass market in a car.
They work well on bikes. I could appreciate 1000bhp hub on my 12kg touring bike. 🤭
I agree, they are good for minimally suspended low speed personal transport.
Renault 5 RS Turbo has hub motors, Nostradamus.
That car is the definition of a party trick. You proved my point, so thank you.
Right, because 2000 of something is not mass production.
And here is a source in China definitely not making >20 hub motors for cars, scooters, etc.
And BMW did not invest $30M in DeepDrive, hub motor supplier.
You should tell these people they are all stupid.
No, less than 2000 cars is not mass market.
Those are golf cart and scooter motors, not suitable for highways
BMW currently uses brushed motors in their EVs so I’m not looking to them for any advice. Maybe BMW wants their traditional central layout CM450 tech. But! DeepDrive is the first hub motor I’ve seen that did not need gearing, so that is actually cool. I think they’ll be relegated to rear wheels due to scrub radius limitations but that could be ok.
That’s because its a limited run show car. Its not meant to be practical.
Imagine on a motorcycle… Probably nonstop wheely 🤣
They make sense for scooters, bikes, and other low speed or two wheel personal transport. For anything with an actual suspension (designed for a highway) there is just too much competition for space with brakes and suspension linkage. The unsprung weight, exposed high voltage cabling subject to road debris and accidents are problems too. And what to do hub motors really gain you?
Simplicity, no transmission. As to unsprung weight, designs like these have a ridiculous power density, so add only very little. Advanced suspensions are active anyway, so just part of the wheel robot.
They DO require transmissions! A single speed planetary gear set is still required, same as current EV drives.
Find me a hub motor datasheet with quoted power and torque below 1000 rpms. The YASA datasheets are all out to 8000 rpms. Useless at wheel speed.
They’re quoting 30 second power numbers and dry weight without a gearbox. They’re fishing for dumb money.
Sure, get semantic.
I’m looking for benefits over current EV drivetrains. So far, there aren’t any.
Less weight, less parts, 4WD, 4W traction control, more cabin space because no driveshafts.
uni-motorcycle
They might work in the rear if used instead of rear brakes. Rears do far less work anyway and brakes are heavy. Powerful electric motors can do a lot of regen, similarly assisting the front brakes.
I’ve had near 8 kilogram rear brake disks on a diesel wagon, not even a performance car that would require huge brakes, current car is 5. Calipers weigh a bunch too. Pads themselves are light, but still add to the whole setup.
This is already pretty close to how many EVs are designed.
Except for the fact that that much power would need massive batteries. So your thin small battery would be dead the first time you mashed the peddle to the floor
forgot the part where they were excited to put the batteries on the tire