hub motors for cars
- Thread starter raylo32
- Start date
Chalo
100 TW
I really like the idea of hub motors for multi passenger vehicles, because it frees them up to carry more and larger payloads in a smaller footprint. But at the speeds today's drivers expect, on the surfaces we have to work with anymore, hub motors seem to present suspension issues that can't be solved without using unnecessary vehicle mass to mitigate their unsprung weight.
We already have unnecessarily heavy cars and trucks. Please no more, thanks.
Maybe if we can realign people's expectations of how fast vehicles should be moving in proximity to people and animals, then hub motor based urban transportation would become feasible. But I think it would take a large scale move to robot taxis or the like to divorce people from their childish need to speed dangerously wherever they go.
We already have unnecessarily heavy cars and trucks. Please no more, thanks.
Maybe if we can realign people's expectations of how fast vehicles should be moving in proximity to people and animals, then hub motor based urban transportation would become feasible. But I think it would take a large scale move to robot taxis or the like to divorce people from their childish need to speed dangerously wherever they go.
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Chalo
100 TW
Ferdinand Porsche made hub motor driven electric cars in 1900. So this isn't a novel idea.
en.m.wikipedia.org
Lohner–Porsche - Wikipedia
lnanek
10 kW
- Joined
- Sep 26, 2022
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Aptera pretty famously gave up on them recently:
cleantechnica.com
Too bad I'm too lazy to shift gears. Otherwise I wouldn't mind replacing my hub motor ebike with a middrive.
Aptera Ditches Hub Motors (For Now), Makes Real Progress Toward 2025 Production - CleanTechnica
Aptera finally gave some more solid details on its plan for producing the ultra-efficient three-wheeled autocycles that have been promised for years. But getting to production means the company had to make some changes, including ditching hub motors for the first vehicles built.
cleantechnica.com
Too bad I'm too lazy to shift gears. Otherwise I wouldn't mind replacing my hub motor ebike with a middrive.
raylo32
100 kW
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I like the idea of having hub motors, but it will be feasible if the road or track is smooth, or has a running track like the urbanloop
I rode on the UrbanLoop , which is a vehicle on steel tracks, using 2 hub motors (72V). The track is very smooth, as it is made with 2 steel rails, so the unsprung weight of the motors wasn't problematic, even at 50km/h
I think hub motors will become lighter, and with a tyre helping to suspend the motor mass, to make them usable on everyday's cars, usable on highways
if the technology don't become lighter, the hub motors will be more suitable for subways or rail tracks, but sadly not for heavy cars, like the Teslas or MG4 (small, lightweight EV cars, like Renault Twizy (the twizy has a classic motor + gearbox currently) would be fine I hope)
I rode on the UrbanLoop , which is a vehicle on steel tracks, using 2 hub motors (72V). The track is very smooth, as it is made with 2 steel rails, so the unsprung weight of the motors wasn't problematic, even at 50km/h
I think hub motors will become lighter, and with a tyre helping to suspend the motor mass, to make them usable on everyday's cars, usable on highways
if the technology don't become lighter, the hub motors will be more suitable for subways or rail tracks, but sadly not for heavy cars, like the Teslas or MG4 (small, lightweight EV cars, like Renault Twizy (the twizy has a classic motor + gearbox currently) would be fine I hope)
raylo32
100 kW
These days they might could make the non electrical basic structure of the hubs out of carbon fiber or some other exotic composite. Might be $$ but that should reduce the weight. CF wheels are already fairly widely available for many sports cars so their strength is proven. Having to also contain and handle a motor will no doubt make it more challenging, but who knows?
Chalo
100 TW
The wheel's structural mass isn't the problem. It's the motor. Electric motors are mature tech and don't have substantial fat to trim, nor big performance gains to be had from additional development.
Making hub motors 10 or 20 percent lighter per HP won't make the basic problem go away, but that degree of improvement is really difficult and expensive to achieve at this point.
Poor ride quality will kill the idea any time.
I dropped ~4lbs off each wheel of my econobox and it made a difference in ride quality i can feel. Imagine going the other way, where you're adding a 40lbs motor on a wheel..
Companies keep trying this and running into the same problem.
I dropped ~4lbs off each wheel of my econobox and it made a difference in ride quality i can feel. Imagine going the other way, where you're adding a 40lbs motor on a wheel..
Companies keep trying this and running into the same problem.
Hillhater
100 TW
And dont forget the Torque factor. Having enough torque to haul a 2000kg vehicle ( with passengers etc) up a steep incline like a garage driveway or multistory parking lot ramp at low speeds…..needs a lot of copper and magnets in those hub motors.
400v, with 500 amps together with inverters and cooling systems in an unsuspended wheel needs some consideration !.
They need to demonstrate the motors on real vehicles to convince buyers.
Chassis mounted motor with reduction drive through drive shafts ( as with most current EVs) avoids so many issues.
400v, with 500 amps together with inverters and cooling systems in an unsuspended wheel needs some consideration !.
They need to demonstrate the motors on real vehicles to convince buyers.
Chassis mounted motor with reduction drive through drive shafts ( as with most current EVs) avoids so many issues.
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Chalo
100 TW
Given that you can have one motor per wheel, and at least four wheels, it doesn't seem like torque is the critical limitation. But keep on straining after gnats and swallowing fossil fueled camels if it gives you joy.
raylo32
100 kW
This, too, could be solved by a computer controlled fully active suspension. Computing power is getting so fast and cheap... add accelerometers, optical and other sensors with motor driven control arms to essentially make the wheels "weightless". I know, sounds complex, but one day it might not be.
Bose developed this a while ago"
Too expensive and heavy apparently and would need to be more so for more unsprung weight.
Or it could be the std: " Oh! nice! When does the patent expire?" thing.
Maybe worth it for heavy hub motors..?
That's extra weight and expense in addition to the already bad weight and expense of a large low RPM electric motor..
The inboard motor is cheaper to produce and makes a lot more sense!
Hillhater
100 TW
Oh, i am sure it will work at some level, Mercedes, Ford, Honda,have previously built test vehicles with hub motors, but with no obvious outcomes ?
Until DeepDrive have their motors independently tested on a vehicle , i will remain sceptical !
Chalo
100 TW
I suspect that hub-like motors connected to CV joints and half axles (with or without planetary reductions gears) are the sweet spot. But all that lost payload volume....
Cars. They suck. They keep finding new ways.
Hillhater
100 TW
Multiple motors, inverter/controllers, gear systems, etc, doesnt sound like a sweet spot to me when compared to a single motor drive train, with a geared differential ( as in most current EVs) .
Yes well, nothing is perfect, and everything is a compromise !
Until someone commercialises Startreks “Transporter beam” ..or similar, a car is the most practical way of taking the family on holiday, kids to sports training, granny to the doctors, etc, ….or commuting to work in bad weather !
Here's some 'Science Fiction' (Ask Chalo) that turns hub motors into the (active) suspension aswell:
That clears the space and weight taken by suspension.
It reduces the unsprung weight down to what? A 5th of what a stock system weighs.
Saves the hub motor/s from all the shock and vibration while allowing the use of powerful, heavy motors.
If we can make one thing do the job of 2 things it's like the move from the horse and carriage to the horseless carriage, now known as the car.
That clears the space and weight taken by suspension.
It reduces the unsprung weight down to what? A 5th of what a stock system weighs.
Saves the hub motor/s from all the shock and vibration while allowing the use of powerful, heavy motors.
If we can make one thing do the job of 2 things it's like the move from the horse and carriage to the horseless carriage, now known as the car.
wturber
1 MW
This reminds me of the days when I was using IRC to discuss 3D animation. This was back when 3D animation was "magic". It seems we had a small but steady stream of people who had interesting ideas on how to improve the program or a new cool plugin that would be nice to have. But these people had zero ability to implement or test out their ideas. As one programmer pointed out to one of these people, "Ideas are a dime a dozen. It's implementation that counts." The idea above is two years old and gives no technical details. And since it hasn't been built, there are is no performance info. No info on how reliable it is. No info on how well it would work with heavy side loads. Maybe its a fantastic idea. But someone needs to build it first. Or to at least run it through some engineering simulations.
LewTwo
1 MW
h'mmm .... many years ago (when working for my rich Uncle Sam) I worked on RT Cranes that used big Cat Diesels to drive hydraulic pumps that fed hydraulic hub motors in each wheel. My point being: are not air or hydraulic motors relatively smaller and lighter (and less complex) than their equivalent BLDC counter parts ? Would a central BLDC driving hydraulic or pneumatic hub motors be another possible sweet spot ?
...just trying to think outside yee old box
...just trying to think outside yee old box
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Couldn't agree more!
And i'm one of those with (close to) zero ability (in this regard) people.
But many here are able. Both financially and in their ability to program SBCs and controllers etc.
So ye; here's hoping it catches the imagination of one of them.
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