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No more brakes for cars of the future:
Electric cars of the future could be able to ditch conventional brake technology in favour of powerful regeneration by battery-powered motors.
[...] Electric cars already use a combination of conventional friction braking and brake regeneration. The latter slows down vehicles using resistance from the same electric motor that propels the car, feeding that energy into the car's battery to extend its range.
DS, Citroen's luxury arm, said it is "exploring whether regenerative braking alone could eventually be the sole method to slow cars down, helping to better recharge the battery in the process, and doing away with conventional brake discs and pads".
[...] [Conventional brake pads and drums] produce "brake dust", fine particles of metallic material that separates from the pad and disc as part of the braking process.
[...] Dr Asma Beji, a non-exhaust particles expert, said in June 2021 that "the impact on health of brake wear particles is undeniable and cannot be neglected".
[...] Environmental researcher Dr Liza Selley, published a paper for the MRC Centre for Environment and Health at King's College London and Imperial College London in 2020 that suggested "diesel fumes and brake dust appear to be as bad as each other in terms of toxicity in macrophages".
[...] "Macrophages protect the lung from microbes and infections and regulate inflammation, but we found that when they're exposed to brake dust they can no longer take up bacteria.
"Worryingly, this means that brake dust could be contributing to what I call 'London throat' – the constant froggy feeling and string of coughs and colds that city dwellers endure – and more serious infections like pneumonia or bronchitis which we already know to be influenced by diesel exhaust exposure."
DS and other manufacturers including Jaguar and Porsche participate in Formula E electric car racing. The series will eliminate rear disc brakes from its next-generation machines in a bid to improve real-world research into the performance potential of purely regenerative braking.
(Score: 2) by mcgrew on Thursday May 12 2022, @08:57PM (3 children)
Regenerative braking fails if there's a failure anywhere in the drive train: the transmission...
Electric motors have the greatest torque at zero RPM and need no transmissions. That's one main reason I want an EV; no oil, tranny fluid, coolant, or gasoline you have to stand there in below freezing weather to fill.
An internal combustion engine and transmission is a primitive Rube Goldberg machine with gears, pumps, pulleys, belts, etc, while an electric motor is sophisticated, having only one moving part. That said, I imagine they'll have some sort of emergency brake, probably friction.
mcgrewbooks.com mcgrew.info nooze.org
(Score: 2) by Immerman on Thursday May 12 2022, @10:03PM
That's true of an idealized electric motor - it's a little more complex than that for real ones.
Most electric vehicles (such as the Teslas) have single-speed transmissions - presumably to map the optimal motor speed to a typical car speed. Electric motors tend to like spinning *fast* - far faster than you'd want your wheels to spin. I believe I recall that the Tesla Roadster actually had a two-speed transmission originally, which was eventually abandoned as it kept being destroyed by the incredible torque from the motor.
(Score: 2) by ChrisMaple on Friday May 13 2022, @03:06AM (1 child)
Calling the rotor of an electric motor a "single part" is an exaggeration. In addition to a shaft, it may have permanent magnets, windings, a commutator or slip rings, and magnetic laminations, depending upon the design.
(Score: 2) by mcgrew on Friday May 20 2022, @12:45AM
True, but they're all connected together and move as one thing. That's far different than all the valves and pistons moving differently from each other in a gas engine, not to mention... well, I'm pretty sure I made my point. I've only had one motor fail that I remember, in my 70 years. I was in the Air Force, and it was the motor in my cassette deck quit. The plastic that had held the rotor's shaft had broken. A little super glue and it was as good as new.
mcgrewbooks.com mcgrew.info nooze.org