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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 RS3 on Thursday May 12 2022, @02:43AM (2 children)
That's very cool. I like the clean simplicity. Nowadays you'd have 200KHz (well, maybe 50-100) choppers, current sensing (back EMF), digital signal processing / analysis, and if done well it might work very well, but much development, and probably not easy to troubleshoot fix someday in the future.
Did you use a "dancer" in your design? (Arm with gentle spring tension and roller at the tip to cushion the start-stop motion).
(Score: 2, Informative) by anubi on Thursday May 12 2022, @08:00AM (1 child)
Yes, we used a dancer, well we called it a tensioner. Mostly gravitic.
It was so we could have a couple of inches of despooled wire free as the despooling inertia and time constants of the despooler were over two orders of magnitude slower than the motions of the weld transducer.
Otherwise, the weld transducer would snap the weld wire in a manner in much the same way we break off a strip of toilet paper by snapping it against the inertia of the roll.
Ours was functionally similar to the vacuum columns used by those old magnetic tape transports. Also, ours had gravitic aspects as gold wire, even at this microscopic size, was still influenced by gravity and we needed to minimize inertia, yet keep the gold wire in a micro-tension at all times.
The whole function of a powered despooler was to maintain that critical length of immediately available wire for the weld head. If it drew wire, and an insufficient amount of wire was available, it would break the wire, which was time consuming and wasteful to re-thread into the weld head.
You've done this. No one who hasn't could not have asked that question. I just typed this much to edify those who haven't.
I look back on this as one of the better designs. Extremely simple. A hybrid analog electromechanical computer, doing some things in the mechanical domain and other things in the analog domain, almost none in the digital domain. There are several places where the analog computation, such as speed and motor current, was done by a PN junction. Just a few CMOS gates and timers. Just turn it on, it works.
"Prove all things; hold fast that which is good." [KJV: I Thessalonians 5:21]
(Score: 3, Interesting) by RS3 on Thursday May 12 2022, @06:43PM
The beauty of simplicity. We have to keep in mind that some people only know digital solutions- they just don't have much mechanical experience, and less analog. I like the blended solution.
Where I work now, food & beverage processing, we have several machines that do similar functions, on a bigger scale of course. Most of them are some kind of labeler. One has a spool of flattened plastic sleeves that get expanded, cut, and dropped onto cans and jars. They then go through a steam tunnel to shrink them onto the container. That machine has a large air box, rather than vacuum, to make a loop to allow for the tugs.
When I was a kid, my dad worked at Univac in their tape drive division and worked on vacuum loop stuff, as well as head read-write amps, etc.
Oh- another labeling machine at work is idiotic. It has dancers that are too short to deliver the entire label, so they have a very powerful servo motor that tries to start and stop, very quickly, a large 18" or so very heavy roll of labels. The idiots used set screws which not only loosen very quickly but gouge the shafts. They didn't even flatten the shafts for the set screws! I fixed it by drilling through the hubs and motor shaft and inserting a roll pin. But you can't get enough friction with the roll, so it doesn't really do what it's supposed to. Much to most people's amazement, I can get the machine to run pretty well, but I'm the only one who can. Other operators / maintenance techs are not engineers, nor have the understanding, patience, nor attention to detail that I have. Point is: I need to modify the dancers- lengthen the lever arm, which isn't too difficult, and should make the machine more friendly to less technical people.
BTW, long ago, 1970s and 80s, a friend's dad worked at GE doing wire bonding, making hybrid circuits that went into satellites, including the still working "LandSat" birds. I can do that level of precision - if I don't have any caffeine that day.