The knee airbag complements the frontal protection system consisting of the seat belt and front airbag, transferring some of the restraining energy to the vehicle via the knees and thighs and increasing occupant protection. This requires that the feet are safely placed in the footwell during a collision. ZamWhen the seats are pulled back into the comfort position, the proper contact point for the feet can be too far away. In the event of an accident, uncontrolled movement of the legs can increase the risk of lower leg injuries. Although most of these injuries are not life-threatening, they can cause long-term damage to the musculoskeletal systems of the driver and front passenger.
Building on this, ZF LIFETEC developed the Active Heel Air Cushion to help create a stable heel strike point even in a relaxed seating position with the seats pushed back.
A number of factors affect the safety of vehicle occupants, including the position of the legs, knees and feet. In normal seating positions, the vehicle floor provides adequate support for the feet of front seat occupants. In the event of an accident, the Active Heel Airbag allows the knee to reach the knee airbag, if fitted in the vehicle, at the most suitable angle. This ensures that a large portion of the crash energy is transferred to the airbag by the thigh, the strongest bone in the human body. However, crash tests have shown that an additional heel contact point is created when the passenger seat is moved back and a more relaxed seating position is adopted.
Safety in Comfortable Sitting Positions
“If the heel strike point is insufficient, the knees cannot reach the airbag effectively, which reduces the effectiveness of the knee airbag,” said Harald Lutz, Development Manager at ZF LIFETEC. Failure to support the knee joints in the desired position results in uncontrolled movement of the legs. This can lead to serious, if not fatal, leg and foot injuries. The absence of the Active Heel Airbag increases this probability. “The Active Heel Airbag helps to ensure a sufficient heel strike point even in more relaxed sitting positions,” Lutz continued.
Space-saving security technology
The Active Heel Airbag can be integrated directly into the footwell without requiring any additional space. In the event of a collision, the airbag inflates under the vehicle’s floor carpet, providing the necessary heel stability. The Active Heel Airbag, which can be adapted to almost all vehicle models worldwide, will be available for car manufacturers in 2028. As a leader in these and other torso protection solutions, ZF LIFETEC continues to set standards in the field of passive safety systems.
