Roofbag:​ a concept study to provide enhanced protection for head and neck in case of rollover

Heudorfer, Benedikt; Breuninger, Martin; Karlbauer, Ulrich; Kraft, Michael; Maidel, Jochen

The purpose of this conceptual study is to address the increasing number of fatalities and severe injuries in vehicle rollovers. A restraint concept for reducing Head and Neck loading by hard contact with the roof of the car has been developed to reduce and/or mitigate these injuries.

The human neck is capable of sustaining higher loads when it is in flexion (e.g. the head is bent forward). Therefore, moving the occupant’s head to a bent forward position using a slowly deploying airbag is proposed.

The Roofbag concept includes a slide chamber and support chamber. Together, they form a multichamber airbag which is mounted at the top of the seat back. The inflator has an extremely slow onset, causing the airbag to deploy in about 250ms. When the slide chamber is inflated, it positions itself behind and above the occupant’s head. The support chamber pushes the slide chamber forward, causing the occupant’s head to bend forward.

Three advantages for this concept have been identified: the occupant’s neck can sustain higher bending loads when positioned in flexion; a cushion is positioned between the occupant’s head and the roof; the survival space between the head and the roof is increased.

A series of rollover tests (SAEJ2114, Curb Trip) using HIII dummies were performed to understand and demonstrate the benefits of this concept. The results show a significant reduction in head and neck injuries when the Roofbag concept is employed. Out-of-position tests show low-to-medium level loadings.

Further potential benefit could possibly result from expanding the Roofbag concept to other applications, such as head protection for convertibles or neck protection during rear impact.

Year

Entry

2003

Praxl N, Schönpflug M, Adamec J. Simulation of occupant kinematics in vehicle rollover: dummy model versus human model. In: Proceedings of the 18th International Technical Conference on the Enhanced Safety of Vehicles (ESV). May 19-22, 2003; Nagoya, Japan.

1995

Rains GC, Kanianthra JN. Determination of the significance of roof crush on head and neck injury to passenger vehicle occupants in rollover crashes. In: Proceedings of the SAE International Congress & Exposition. February 27–March 2, 1995; Detroit, MI. Warrendale, PA: Society of Automotive Engineers. SAE 950655.

1972

Hight PV, Siegel AW, Nahum AM. Injury mechanisms in rollover collisions. In: Proceedings of the 16th Stapp Car Crash Conference. November 8-10, 1972; Detroit, MI. Warrendale, PA: Society of Automotive Engineers:204-227. SAE 720966.

1991

Nightingale RW, Doherty BJ, Myers BS, McElhaney JH, Richardson WJ. The influence of end condition on human cervical spine injury mechanisms. In: Proceedings of the 35th Stapp Car Crash Conference. November 18-20, 1991; San Diego, CA. Warrendale, PA: Society of Automotive Engineers:391-399. SAE 912915.

2001

Ridella SA, Nayef A, Altamore PF. Rollover: a methodology for restraint system development. In: Proceedings of the 17th International Technical Conference on the Enhanced Safety of Vehicles (ESV). June 4-7, 2001; Amsterdam, The Netherlands.