Interesting to say the least, good post. David Ferrin Life is what happens after you've already made other plans. ----- Original Message ----- From: "Ray Boyce" <[EMAIL PROTECTED]> To: <[email protected]> Sent: Sunday, October 12, 2008 1:00 AM Subject: [BlindHandyMan] : Automobile airbags
> It's been 20 years since airbag systems started appearing in automobiles. > Just like other automotive systems, airbags have undergone major changes > since their introduction and the newer designs protect us better than > ever. > > The first airbags were mounted only in the steering wheel, for driver > protection from the impact against the steering column. These were simple > systems compared to the current designs, but still had to be robustly > designed to work the first time, every time, even after years of service. > They used mechanical sensors to determine impact loads: some of them have > a > gold-plated steel ball held in a tube by a magnet. An impact with enough > force would jar the ball loose from the magnet and it would roll ahead, > touching two gold-plated contacts to complete an electrical circuit that > ignited the airbag. Gold is used so the electrical contacts won't corrode > over time. Many of these early systems ignited sodium azide, a solid > rocket > propellant, to inflate the airbag in a fraction of a second. > > About the mid nineties, we started seeing airbags on the front passenger's > side. These bags are larger, because typically they are further away from > the vehicle occupants. Sodium azide was used to inflate some of these > systems but others used a compressed gas cylinder. An explosive charge > punctures the end of the cylinder allowing the gas into the airbag. Heat > from the charge helps the gases expand so the airbag deploys quicker. > > Side impact and side curtain airbags also started appearing in the late > 1990s. Each has a distinct purpose. The side impact bags are often mounted > in the side of the front seats, although there are some side airbags > located > behind the door panels or in the doorjamb post (B pillar). These side > impact > airbags help protect passengers from a side impact, and because there is > very little time from the point of impact until the passenger compartment > is > affected, the side impact airbags have to deploy much faster than frontal > airbags. > > Side curtain airbags are located above the doors under the vehicle > headliner. They were initially designed to protect passengers if the > vehicle > was involved in a roll over, but the newer systems may also deploy in a > side > impact if the collision is severe enough. Side curtain airbags are big, > covering the complete side glass. Some systems cover only the front and > second row seats, while others will cover three rows of seats if the > vehicle > is so equipped. Side curtain airbags also deploy for much longer than > other > airbags. Within a second, other airbags will be collapsing, but side > curtain > airbags may stay inflated for up to 6 seconds. They are calibrated this > way > because a roll over event can take several seconds to occur, until the > vehicle stops. > > The next big step in airbag development came with dual-stage frontal > airbags. These systems have two separate charges and igniters. Depending > on > the severity of the impact, one or both stages may deploy. The sensors > used > on these systems are much more sophisticated, using G-sensors and load > cells > to send information on the severity of the impact to a computer. The > computer also monitors things like seat belt latches and front seat > position > to determine how to deploy the airbags. > > By 2007, vehicles in Canada required an occupant sensor for the front > passenger seat. These sensors, and there are several different types, from > ultrasonic to a capacitance mat, tell the airbag computer if there is a > passenger in the seat. Some systems will signal if a passenger is in the > correct position. If there is no passenger, the passenger side airbags > should not deploy in a collision, saving on repair costs. > > There are still more advances in airbag technology to come. Just this past > week, Honda announced a new driver's side airbag with continuously staged > inflation. This airbag has a spiral-shaped seam structure and gas release > control valve to control airbag deployment. It can be deployed faster but > also reduces occupant impact compared to a conventional airbag by having a > longer inflation time. Remember that when we talk about long inflation > times, it is still measured in milliseconds. Without a high-speed camera > recording the deployment, you would never see it. This new airbag design > also contains all the inflation gases until it is time to deflate, unlike > present systems that start exhausting gases even as the airbag inflates. > This allows the new Honda system to remain inflated longer. > > The new Honda airbag will be introduced in November in the Japanese > market, > on the Honda Life minicar, but I suspect we will see it here in short > order > too. > > Jim Kerr is a master automotive mechanic and teaches automotive > technology. > He has been writing automotive articles for fifteen years for newspapers > and > magazines in Canada and the United States, and is a member of the > Automotive > Journalist's Association of Canada (AJAC). > > > > > > [Non-text portions of this message have been removed] > > > ------------------------------------ > > Send any questions regarding list management to: > [EMAIL PROTECTED] > To listen to the show archives go to link > http://www.acbradio.org/pweb/index.php?module=pagemaster&PAGE_user_op=view_page&PAGE_id=33&MMN_position=47:29 > Or > ftp://ftp.acbradio.org/acbradio-archives/handyman/ > > The Pod Cast address for the Blind Handy Man Show is. > http://www.acbradio.org/news/xml/podcast.php?pgm=saturday > > Visit The Blind Handy Man Files Page To Review Contributions From Various > List Members At The Following address: > http://www.jaws-users.com/JAWS/handyman/ > > Visit the archives page at the following address > http://www.mail-archive.com/[email protected]/ > > If you would like to join the JAWS Users List, then visit the following > address for more information: > http://www.jaws-users.com/ > For a complete list of email commands pertaining to the Blind Handy Man > list just send a blank message to: > [EMAIL PROTECTED] Groups Links > > >
