Ford has developed a new cost-saving and award-winning knee airbag system using injection molded plastics that it feels will revolutionize the airbag industry.
In the new approach, an airbag is integrated into the glove box door, saving packaging space within the instrument panel while providing an overall weight savings in the vehicle. There is no compromise in performance compared to conventional woven textile knee airbag mounted under the instrument panel, according to Ford engineers. A video shows how the system works. The all-new Mustang has twice as many airbags and twice as many peripheral crash sensors compared to the outgoing model.
“We provide a high level of safety, quality and design for our customers and their passengers,” says Sean West, Ford restraints manager. “With this innovative airbag design, we have developed technology that provides protection for vehicle occupants while also reducing weight and enabling greater design flexibility.” There are no visible seams or airbag cover.
A combination of three plastic materials is used in an injection-molded plastic bladder sandwiched between the inner and outer glove box door panels. After a vehicle impact is detected by the crash sensor system and classified, an inflator fills the bladder, extending the entire glove box outer door panel toward the front passenger’s legs. Once deployed, the outer door helps to provide cushioning in a manner similar to a traditional knee airbag.
Materials used are:
- A 20 percent talc-filled polypropylene (PP) from Advanced Composites that includes high rubber content for cold ductility. The grade is ADX 5028.
- Another 20 percent talc-filled PP (ADX 5017) that is stiffer than 5028 to provide a reaction surface.
- Airbag door-grade TPO from Mitsubishi (TT850N) that is said to perform well at high strain rates at hot and cold temperatures.
A hermetic seal that forms the airbag is created by hot plate welding the bladder to the outer door. Weld strength requirements between the bladder and door inner differ from that between the door inner and door outer, says Ford. Four different tests of weld strength are used as process controls.
The new approach, called “active glove box” is standard equipment on the 2015 LHD Mustang and on the 2016 Europe LHD & RHD Mustang. Fifteen patents have been granted for the technology.
The active glove box/integrated knee airbag supplier is Faurecia. Hot plate welding development was done by Extol, Inc.
“The new Mustang has increased ability to adapt safety systems to a variety of potential situations,” says Jeff Rupp, Mustang safety systems manager.
The technology is the safety category and Grand Prize Winner in the Society of Plastics Engineers’ Automotive Division’s 44th-annual Automotive Innovation Awards Competition. Category winners and the Grand Award winner were announced Nov. 12 at an awards banquet.