Enhanced passenger protection: active head restraint and anti-submarining ramp
September 20, 2005 At this year’s Frankfurt Motor Show, Johnson Controls revealed some novel occupant protection concepts: two new versions of an active head restraint and an active anti-submarining ramp. The new solutions are designed to reduce the risk of whiplash and of injuries to passengers' pelvis and legs. By contrast with conventional solutions, new technologies have enabled Johnson Controls to optimize the functionality of both the active head restraint and the active anti-submarining ramp. Thus, they can react faster and more reliably to enhance occupant protection. In addition, these products can easily be integrated into existing seating systems.
In recent years, technological progress has made driving significantly safer. In spite of this, neck injuries with long-term impairment effects are one of the most frequent accident injuries. Johnson Controls’ active head restraint helps to reduce risk of injury to vehicle passengers: in case of rear impact, the head restraint reduces hyperextension of the vertebral column, thus lowering or ideally even eliminating the risk of whiplash. Automakers can choose between two versions when integrating the active head restraint system. The first option is body driven, mechanically activated by the body weight of the occupant when there is a crash. The other version is triggered electronically by the crash sensor which also sends information to the airbags.
Optimized release with mechanical systems A new feature of the body-activated head restraint from Johnson Controls is that the release mechanism was integrated into the lower part of the backrest. In case of rear impact, the mechanism is activated by the passenger’s pelvis. The advantage of this integration position is that the pelvis is the part of the body that has maximum contact with the backrest. In most conventional systems, activation takes place in the upper backrest area. This is a disadvantage for occupants who are small or slight, since activation of the head restraint cannot always be guaranteed. A particular benefit of this system is that the body-driven technology can be integrated into the seat at a relatively late stage in the assembly process. In addition, the same backrest frame can be used as in standard seats. The mechanism will be integrated into series production from the end of 2006.
Connection to airbag electronics with particularly fast release
The sensor-triggered active head restraint from Johnson Controls does not use a mechanism in the lower backrest area. Instead, the system takes its information from sensors such as those that are used for airbag control, and analyzes this information based on certain algorithms. About 20 milli-seconds after the signal has been received, the head restraint has already reached its final position. Small pyrotechnical units or electromechanical mechanisms release the system.
Support for the lap belt
In addition to neck injuries, leg and pelvis injuries are also high on the list of accident statistics. Here, it is front-end collision that causes problems when the knees hit the instrument panel. This type of injury occurs even more often when the lap belt is not strapped tightly, allowing the body to slide under the belt. To reduce this “submarining” effect, Johnson Controls developed a new active ramp which is integrated into the area of the seat pan.
In case of front-end collision, the ramp rises quickly. Forward movement of the pelvis is restrained by the bar in the front part of the seat and is reduced by approximately one third compared to double pretensioners. If the occupant is seated in the correct position, contact with the instrument panel can be prevented. At the same time, the belt forces acting on the body are reduced.
In contrast to double pretensioners, the new anti-submarining ramp can be used for three- and five-door vehicle models alike. This patent-pending technology will be available for model year 2007.
Yaniv Oren, Director Product and Business Development Seating at Johnson Controls: “Through our solutions for occupant protection, we are helping our customers in the automotive industry to make driving even safer in the future.”