Facts About Automotive Airbags
Automotive airbags started out as a selling feature appealing to a potential car buyers desire to keep themselves and family members safe during a violent collision. What started out as a single airbag behind the horn pad cover of the steering wheel has evolved into a series of inflatable restraints surrounding the driver and passengers of the vehicle. Now the number of airbags has become the selling point with the higher number appealing to safety conscious consumers. This article covers the basic features, operation and characteristics about this important safety system.
What is an Airbag
In the event of a violent collision the vehicle stops traveling suddenly, but the human body continues to move forward. The airbag is a nylon fabric balloon that quickly inflates to slow down and then stop the forward momentum of the driver and passenger’s upper body. It’s this gradual reduction of body speed that helps prevent catastrophic injury.
Airbags and Seatbelts
It’s important to remember the effectiveness of this safety tool depends on the driver and passengers wearing seat belts to hold them in the perfect position for the airbag to perform its task. In other words deployment of the airbag is a waste of time unless the occupants are buckled in. In crash tests performed on dummies that weren’t wearing seat belts in a head-on collision resulted in the airbag contacting the waist area instead of the head and chest as per its design intent. In the high-speed tests the airbag would often contact the crash test dummy well below the waist as they traveled through the windshield.
Airbag Speed of Deployment
One of the most amazing facts about automotive airbags is the speed at which they inflate. From the time they’re triggered by the impact sensors to the point where they’ve finished performing the job completely is less than one second. It only takes 20 to 25 ms (milliseconds) from the point of impact to the beginning of airbag deployment. Within another 5 ms the airbag is nearing full inflation and has made contact against the passenger’s chest area.
At this point the occupant’s body hasn’t even begun its forward movement from the crash event. 10 ms later and About 40 milliseconds after impact the airbag is just about fully deployed and begins to absorb the occupants forward motion. Within another 30 ms the airbag starts to deflate yet continues to absorb the impact. At about this time totaling around 70 ms after the crash the airbag has just about finished its task of cushioning the blow.
First Generation Airbags Deployed too fast
The deployment of inflatable restraints can be a violent experience. Minor injuries from the inflation were considered better than the catastrophic injuries of the accident itself. A second generation of airbags is finding its way into automobiles that slow down the rate of deployment by using less powerful inflation techniques. This helps accommodate different sized occupants and has been effective in reducing the number of injuries caused by the airbag safety system itself.
The second generation of airbags uses less inflation pressure and controls the rise rate which is the measurement of speed at which an airbag inflates. They control the rise rate using two main factors. The first is the size and manner in which the inflation gas is vented. Larger faster acting vents can slow down the rise rate and reduce total pressure. The second method is the design, size, and shape of the airbag itself. Overall these second generation inflatable restraints are able to provide the same protection with a 20 percent reduction in total force used to inflate a first-generation restraint.
Airbags started out as a selling tool with a single airbag hiding in the steering wheel. These have blossomed to surround the driver and passengers with side curtain, knee bolsters, seat belt mounted and even door panel mounted side impact protection airbags. The success of the system depends on the driver and passengers wearing seat belts to hold them in position as the airbags inflate around them. This makes buckling up the most important thing you can do to protect you and your passengers in the case of an accident.