Re: [EVDL] Bosch pyroswitches/pyrofuses> 1 bash& EV's wiring is shot
On Tue, 8 Oct 2019 at 15:57, EVDL Administrator via EV wrote: > Am I missing something? Isn't this what main contactors are for? A short circuit of the main battery bus during an impact could weld contactors, particularly as there may be contact bounce due to the impact. A fuse might not blow, because the sustained fault current isn't high enough. A one time operable disconnect sounds like a good idea. Cutting cables doesn't, but then that is probably just bad reporting of the actual process. -- Paul Compton www.morini-mania.co.uk www.paulcompton.co.uk (YouTube channel) ___ UNSUBSCRIBE: http://www.evdl.org/help/index.html#usub ARCHIVE: http://www.evdl.org/archive/index.html INFO: http://lists.evdl.org/listinfo.cgi/ev-evdl.org Please discuss EV drag racing at NEDRA (http://groups.yahoo.com/group/NEDRA)
Re: [EVDL] Bosch pyroswitches/pyrofuses> 1 bash& EV's wiring is shot
Am I missing something? Isn't this what main contactors are for? Besides, I don't think its a new idea. This document https://www-esv.nhtsa.dot.gov/proceedings/24/files/24ESV-000163.PDF seems to date from a couple of years ago (I could be wrong about that, however). David Roden - Akron, Ohio, USA EVDL Administrator = = = = = = = = = = = = = = = = = = = = = = = = = = = = = EVDL Information: http://www.evdl.org/help/ = = = = = = = = = = = = = = = = = = = = = = = = = = = = = Note: mail sent to "evpost" and "etpost" addresses will not reach me. To send a private message, please obtain my email address from the webpage http://www.evdl.org/help/ . = = = = = = = = = = = = = = = = = = = = = = = = = = = = = ___ UNSUBSCRIBE: http://www.evdl.org/help/index.html#usub ARCHIVE: http://www.evdl.org/archive/index.html INFO: http://lists.evdl.org/listinfo.cgi/ev-evdl.org Please discuss EV drag racing at NEDRA (http://groups.yahoo.com/group/NEDRA)
Re: [EVDL] Bosch pyroswitches/pyrofuses> 1 bash& EV's wiring is shot
Seems this could create as many hazards as it stops. First, the author mentions the pyroswitch might fail. So you still have to execute caution. Other failures could happen, too: - the "hot" cut wire could touch the chassis due to deformation during the crash - some other short-to-chassis from the battery could occur - not all vehicles may have a pyroswitch - the disconnection might arc and start a fire On top of that, as they say, it creates substantial additional expense to repair. Do you want that every time you go over a really bad pothole :) Safety features are paramount, so I support the intent. Not sure this is a good solution, though. Peri -- Original Message -- From: "brucedp5 via EV" To: ev@lists.evdl.org Cc: "brucedp5" Sent: 08-Oct-19 1:09:04 AM Subject: [EVDL] Bosch pyroswitches/pyrofuses> 1 bash& EV's wiring is shot https://www.wired.com/story/evs-fire-pyroswitches-cut-risk-shock-crash/ EVs Fire Up Pyroswitches to Cut Risk of Shock After a Crash 10.06.2019 Alex Davies [images https://media.wired.com/photos/5d97dafc01e4a400082613b3/master/w_2560%2Cc_limit/Transpo_carcrash_KGGNX5.jpg Photograph: Alamy https://media.wired.com/photos/5d97daa428aa88000843488a/master/w_1280%2Cc_limit/Transpo_Bosch_Airbag_IC_Print-(300-dpi).jpg EV chip Bosch developed the CG912 semiconductor chip for triggering airbags, but it works just as well for sparking a tiny guillotine to cut an electric vehicle’s high-voltage cables. Illustration: Bosch ] Electric cars run on 400 volts or more. So automakers are designing systems to protect EMTs and others from exposed wires following a collision. After more than a century of powering their wares with engines that produce hundreds of small, carefully controlled explosions each minute, the auto industry is moving toward a battery-driven future. But that doesn’t mean one without any helpful explosions. Last month, industry supplier Bosch revealed details on what it calls the pyrofuse, a new safety tool for electric cars. When the system detects a crash, its uses a bit of combustion to fire small wedges into the high-voltage cables, severing the connections between the battery and the power electronics. The idea is to reduce the risk of electrocution for first responders. Here’s why that’s necessary: Conventional cars run about 12 volts of power, but many electrics use 400 volts. The new Porsche Taycan uses double that. That power bump has pushed the auto industry to develop new ways to keep everybody safe. Along with careful insulation of battery packs and high-voltage components, automakers and suppliers have developed a variety of pyrotechnic safety switches that activate in the event of a crash. Autoliv’s Pyroswitch throws a switch to disconnect the power source from the circuit board. Tesla has patented an “arc-suppressing gas blast in pyrotechnic disconnect” [ https://insideevs.com/news/334322/tesla-patents-pyrotechnic-battery-safety-device/ ] that appears to work similarly. Bosch’s system goes further by actually cutting wires. “It’s a secure disconnection,” says Thorsten Koepke, the company’s product manager for semiconductors, “a physical opening of the wire.” His team produced the chip that uses deceleration and other data from the car to identify a crash. They originally developed the chip for use in airbags, but it serves the same function here. The exact workings of the system, including the conditions under which it will trigger, are up to the automaker, but the general idea is that the chip triggers a small explosion, similar to the chemical reaction that inflates an airbag. But here it will launch wedges into the wires in question—as many as eight, if the car has a motor at each wheel, Koepke says. And while Bosch declines to name its clients, Koepke says it’s already in use in cars on the road. “It’s like a little guillotine.” -Huseyin Hiziroglu, Kettering University Pyroswitches are relatively common, but this use case is novel, says Huseyin Hiziroglu, an electrical engineer at Kettering University in Flint, Michigan. “It’s like a little guillotine.” One that looks to save lives instead of take them but that delivers the same sort of permanence. The downside of this safety-minded system is that repairing a crashed electric car will involve installing a lot of new wiring. Which means, most likely, spending a lot of money. “I’m sure it will be quite expensive,” Hiziroglu says. Jason Siegel, a research scientist at the University of Michigan who studies lithium-ion batteries, says pyrofuses “can provide a much-needed safety net for first responders.” But it’s not clear that taking the extra step of severing the wires will change how EMTs and others approach a crashed vehicle, since they won’t know that the little guillotine has done its work. “I don’t see first responders reaching for a [voltage-measuring] Fluke meter to check if the wires are live before cutting when someone i
[EVDL] Bosch pyroswitches/pyrofuses> 1 bash& EV's wiring is shot
https://www.wired.com/story/evs-fire-pyroswitches-cut-risk-shock-crash/ EVs Fire Up Pyroswitches to Cut Risk of Shock After a Crash 10.06.2019 Alex Davies [images https://media.wired.com/photos/5d97dafc01e4a400082613b3/master/w_2560%2Cc_limit/Transpo_carcrash_KGGNX5.jpg Photograph: Alamy https://media.wired.com/photos/5d97daa428aa88000843488a/master/w_1280%2Cc_limit/Transpo_Bosch_Airbag_IC_Print-(300-dpi).jpg EV chip Bosch developed the CG912 semiconductor chip for triggering airbags, but it works just as well for sparking a tiny guillotine to cut an electric vehicle’s high-voltage cables. Illustration: Bosch ] Electric cars run on 400 volts or more. So automakers are designing systems to protect EMTs and others from exposed wires following a collision. After more than a century of powering their wares with engines that produce hundreds of small, carefully controlled explosions each minute, the auto industry is moving toward a battery-driven future. But that doesn’t mean one without any helpful explosions. Last month, industry supplier Bosch revealed details on what it calls the pyrofuse, a new safety tool for electric cars. When the system detects a crash, its uses a bit of combustion to fire small wedges into the high-voltage cables, severing the connections between the battery and the power electronics. The idea is to reduce the risk of electrocution for first responders. Here’s why that’s necessary: Conventional cars run about 12 volts of power, but many electrics use 400 volts. The new Porsche Taycan uses double that. That power bump has pushed the auto industry to develop new ways to keep everybody safe. Along with careful insulation of battery packs and high-voltage components, automakers and suppliers have developed a variety of pyrotechnic safety switches that activate in the event of a crash. Autoliv’s Pyroswitch throws a switch to disconnect the power source from the circuit board. Tesla has patented an “arc-suppressing gas blast in pyrotechnic disconnect” [ https://insideevs.com/news/334322/tesla-patents-pyrotechnic-battery-safety-device/ ] that appears to work similarly. Bosch’s system goes further by actually cutting wires. “It’s a secure disconnection,” says Thorsten Koepke, the company’s product manager for semiconductors, “a physical opening of the wire.” His team produced the chip that uses deceleration and other data from the car to identify a crash. They originally developed the chip for use in airbags, but it serves the same function here. The exact workings of the system, including the conditions under which it will trigger, are up to the automaker, but the general idea is that the chip triggers a small explosion, similar to the chemical reaction that inflates an airbag. But here it will launch wedges into the wires in question—as many as eight, if the car has a motor at each wheel, Koepke says. And while Bosch declines to name its clients, Koepke says it’s already in use in cars on the road. “It’s like a little guillotine.” -Huseyin Hiziroglu, Kettering University Pyroswitches are relatively common, but this use case is novel, says Huseyin Hiziroglu, an electrical engineer at Kettering University in Flint, Michigan. “It’s like a little guillotine.” One that looks to save lives instead of take them but that delivers the same sort of permanence. The downside of this safety-minded system is that repairing a crashed electric car will involve installing a lot of new wiring. Which means, most likely, spending a lot of money. “I’m sure it will be quite expensive,” Hiziroglu says. Jason Siegel, a research scientist at the University of Michigan who studies lithium-ion batteries, says pyrofuses “can provide a much-needed safety net for first responders.” But it’s not clear that taking the extra step of severing the wires will change how EMTs and others approach a crashed vehicle, since they won’t know that the little guillotine has done its work. “I don’t see first responders reaching for a [voltage-measuring] Fluke meter to check if the wires are live before cutting when someone is trapped in the vehicle,” he says. There are more than a million electric cars roaming American roads, but, so far, worries around high-voltage crashes haven’t come to fruition. Andrew Klock, who works on EVs and other emerging issues for the National Fire Protection Agency, says he doesn’t know of any first responders who have been zapped. The nonprofit group has trained 225,000 EMTs, firefighters, police, and others to deal with electric cars in the past decade. Relatively simple advice has proven effective. “You just stay away from any broken cables,” Klock says. First responders who need to cut someone out from a mangled vehicle can check the agency’s Emergency Field Guide, which collects and standardizes key information on all the electric car models on the market, to make sure they’re well clear of any cables or components that could deliver a deadly shock. Stay away from those, Klock says,