Of the roughly 25,000 souls that perish inside a car on American roadways each year, roughly a quarter of those are passengers. Honda has developed a new type of airbag targeted at saving those lives in particular.
There are many things you’d expect to see in a modern automotive research facility. Robots, sheet metal, crash test dummies, and hundreds of engineers hunched over hundreds of computer monitors are certainly on the list.
You wouldn’t expect, however, a pair of sewing machines – the kind that wouldn’t look out of place in your crafty grandmother’s spare bedroom.
But, at Honda Research and Development in Raymond, Ohio, engineer Eric Heitkamp occasionally threads a bobbin and stitches up new designs for airbags. After all, it’s just cloth. This cloth, however, offers an opportunity to keep passengers safer, and today Honda revealed a new technology that helps protect even those passengers who aren’t sitting in the ideal upright position.
In 2017 alone, a total of 24,973 people died on American roadways and roughly a quarter of those were passengers, at the mercies of fate, the driver of their car, and the whatever circumstances led to the collision. Throughout the past 24 years indeed, between five and ten thousand passengers per year die in a car they aren’t piloting.
As we all know, sitting in a passenger seat can be mind numbing, so we look for ways to while away the time. Often, passengers will shift in their seat to face the driver or other passengers, or even nod off leaning on the window or with chin to the chest. In these situations especially, coming to a rapid stop due to a collision can cause a form of traumatic brain injury known as a diffuse axonal injury.
In short, the diffuse axonal injury is a concussion where the skull doesn’t necessarily receive a direct impact. Rather, this injury occurs when the skull rotates more rapidly than the brain, essentially causing the grey matter to slosh around the skull, causing traumatic shearing. Recently, F1 driver Jules Bianchi succumbed after 9 months in a coma after suffering a crash with a safety vehicle at the 2014 Japanese Grand Prix. Doctors confirmed that Bianchi’s injury was a diffuse axonal injury.
It’s also the same type of injury that occurs in shaken baby syndrome.
Eric Heitkamp, crashworthiness technical leader and principal engineer at Honda R&D, worked with his team and an airbag supplier, Autoliv, to develop a next-generation airbag system specifically engineered to minimize the consequences to an out-of-position passenger.
In a traditional airbag, one large chamber inflates upon impact – but that chamber can be a significant distance from the passenger’s head, allowing inertia to keep the passenger moving forward rapidly until it meets a firmly-inflated pillow of gas. That large pillow, if the passenger is coming at an angle – if they were leaning on the window, for example – could potentially deflect the head, causing rotation that could lead to that diffuse axonal injury.
This newly-patented airbag uses three inflating components – one wide center chamber, flanked on each side by outward-projecting side chambers that bring the “pillow” closer to the occupant. Stretched between those outboard chambers is what Honda refers to as a “sail panel,” essentially a section of cloth that doesn’t inflate.
Heitkamp notes that this sail panel stretching between the inflated side chambers creates a large uninflated area that creates an “early, soft engagement” between the passenger’s head and the restraint. Honda likes to use a baseball catcher’s mitt analogy – after all, a catcher has to gather up a hard, round object and keep it both from hurting his hand and from bouncing away.
Looking at this video, it seems that the airbag is hugging the passenger during the collision. After all, who doesn’t love the soft, warm embrace of their supplemental restraint system?
There isn’t an accepted standard for brain-specific injuries – the industry has long used a standard known as HIC (Head Injury Criterion) – but Honda and others use a metric known as BrIC – Brain Injury Criterion – to assess the risk. It’s being debated throughout the industry, and the math is well beyond your author who couldn’t manage high-school calculus, but the SAE has a technical paper here that discusses the merits of the various calculations. Heitkamp notes that the next-generation airbag leads to a 75% reduction in BrIC. Again, as this metric isn’t standardized, it’s hard to extrapolate the exact life-saving numbers from a BrIC reduction, but certainly any significant impact to that figure should yield a better outcome for most people unfortunate enough to see the working end of this explosive device.
Many of the calculations used in developing this next-generation airbag were generated via Honda’s crash simulator sled, which employs 555,000 horsepower to hydraulically pitch a test rig rapidly at any angle. Here, the rapid acceleration simulates the rapid deceleration of an impact without the pesky details of sweeping up busted sheetmetal every day. This way, they can tune and optimize every component of the interior – airbags, seat belts, and even the dashboard – to lessen the chance of injury.
Honda and Autoliv will be putting this next-generation airbag into production into an unspecified car in calendar year 2020. As Autoliv shares the patent and is an independent supplier, it will be available to other automakers in the future.
[Images: © 2019 Chris Tonn, Honda. Videos courtesy Honda]