Adjustable Brake Torque Energy Absorber for Aircraft Seat Crash Protection
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Solution Overview
Problem
Existing energy absorption systems in vehicle seats, particularly in aircraft, suffer from irreversible deformations and are not effectively adaptable to the varying weights of occupants, leading to incomplete protection during crashes, as they either compromise on acceleration limits or require complex and costly solutions.
Innovation Solution
An energy absorber system featuring a winding drum with a mechanically coupled disc brake and a spring element, allowing for adjustable maximum brake torque through a control member, which winds a traction line to apply a constant force independent of the occupant's mass, thereby controlling acceleration during strong accelerations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If energy absorption devices are designed as a compromise between lightest and heaviest passenger mass, then the device can be universally applicable, but the acceleration protection is incomplete for extreme cases (lighter occupants experience greater acceleration, heavier occupants experience greater movement amplitude)
Solution Approach 1:
The brake torque is made adjustable through a control member that modifies the compression of the spring element, allowing the energy absorption characteristics to be dynamically adapted to different passenger masses. This transforms a static compromise design into a dynamic system that can be optimized for each specific use case.
Solution Approach 2:
The maximum brake torque parameter is made variable through the control member mechanism. By adjusting the spring element compression, the system can change the brake torque parameter to match different passenger masses, thereby optimizing acceleration protection for each individual case rather than relying on a fixed compromise value.
2Reliability
If complex solutions are implemented to adapt energy absorber to occupant weight, then acceleration protection can be optimized, but the system becomes more expensive and less reliable
Solution Approach 1:
The control member serves multiple functions: it adjusts the spring element compression, modifies the maximum brake torque, and adapts the energy absorption characteristics to different passenger masses. This multi-functionality is achieved through a single, relatively simple mechanical component rather than a complex system of sensors, actuators, and control electronics.
Solution Approach 2:
The system uses the passenger's own weight to automatically determine the appropriate brake torque setting through the mechanical interaction of the control member with the spring element. The heavier the passenger, the greater the compression force required, which naturally adjusts the system parameters without requiring external input or complex control logic.
3Use of energy by moving object
If existing energy absorption methods are used, then some energy can be absorbed, but irreversible deformations occur preventing individual testing and restoration
Solution Approach 1:
The brake components (spring element, friction elements) are designed as replaceable wear parts that can be individually tested and restored or replaced after a crash event. This approach treats the energy absorption components as consumable elements that protect the more valuable and complex structural components of the seat, enabling cost-effective restoration rather than complete system replacement.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This system effectively limits acceleration to a predetermined value for occupants of varying weights, ensuring consistent protection without irreversible deformation, allowing for individual testing and restoration, and is suitable for both aircraft and other vehicles with strong acceleration components.
Implementation Method 1
a spring element is mounted in compression between two sub-assemblies of the brake, each sub-assembly comprising elements rotor and stator mounted alternately and movable in a direction of an axis of rotation of the rotor, so as to exert a bearing force which is applied between the rotor elements and the stator elements in contact
Implementation Method 2
the friction force between the rotor and the stator determining the value of the maximum brake torque
Data Source
Figure 1a~2b
Figure 3~4
Figure 5
AI summary
An energy absorber (100) for mitigating the acceleration force experienced by a heavy body, such as a seat occupant subjected to the acceleration of an aircraft crash, comprises a winding drum (10) mounted for rotation around a shaft (13) around which a traction line (11) is wound. The shaft is mechanically coupled to a brake (20) which prevents the shaft (13) from rotating when a torque applied to the shaft by the traction line is less than the maximum braking torque that can be generated by the brake, and which, when the shaft (13) is rotating, generates a substantially constant torque equal to the maximum braking torque. A control element (40) acting on the brake (20) allows the value of the maximum braking torque to be modified and thus the energy absorber to be adapted to the mass of the heavy body in order to maintain the acceleration experienced at a desired value for different masses.