Aircraft Seat Transmission Locking for Crash Load Absorption
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Solution Overview
Problem
Aircraft seat drive systems face challenges in withstanding sudden loads during crashes and repeated stress without breaking or wearing prematurely, leading to oversizing of mechanical parts which increases manufacturing costs and weight, contradicting the goal of reducing aircraft weight for fuel efficiency and environmental impact.
Innovation Solution
Aircraft seat transmission device featuring a frame with a through bore and a drive body with elastic elements, such as spring washers or Belleville washers, that compress and engage braking faces to absorb excessive forces, allowing the actuator and mechanical parts to operate within a normal size range, thus reducing the need for oversized components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If mechanical components are oversized to withstand crash loads, then reliability is improved, but weight increases
Solution Approach 1:
The transmission chain is segmented into a normal operating channel and a dedicated crash load channel. The normal channel includes the actuator and standard mechanical components, while the crash channel includes the locking mechanism with braking surfaces that engage during crashes. This segmentation allows each channel to be optimized independently, enabling the normal channel components to be smaller while the crash channel handles excessive forces.
Solution Approach 2:
The locking mechanism acts as an intermediary element between the actuator and the seat assembly. During normal operation, it remains disengaged and does not interfere with standard operation. During crashes, it engages to absorb and dissipate excessive forces through friction between braking surfaces, protecting the actuator and other mechanical components from damage.
2Reliability
If mechanical components are oversized to withstand repeated sudden loads, then reliability is improved, but manufacturing cost increases
Solution Approach 1:
The transmission system is divided into two functional segments: the normal operating transmission chain and the crash load management system. This allows standard mechanical components to be manufactured at normal specifications rather than oversized specifications, reducing manufacturing costs while maintaining reliability through the dedicated crash handling capability of the locking mechanism.
Solution Approach 2:
The locking mechanism uses friction-based braking surfaces that can wear over time from repeated crash events. These braking surfaces are designed to be replaceable and relatively simple in construction, allowing the system to handle repeated sudden loads economically rather than requiring expensive oversized components throughout the entire transmission chain.
3Reliability
If mechanical components are oversized to prevent premature wear, then reliability is improved, but device complexity increases
Solution Approach 1:
By segmenting the transmission system into normal operation and crash load paths, the patent prevents premature wear in the normal path components by isolating them from crash loads. The locking mechanism with its braking surfaces is specifically designed to handle wear from repeated crash events, protecting the more complex and expensive actuator and transmission components from wear.
Solution Approach 2:
The locking mechanism serves as an intermediary that intercepts and manages crash loads before they can reach and wear the actuator and other mechanical transmission components. This protective function extends the service life of the main transmission components without requiring them to be oversized or overly complex.
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 solution enables the aircraft seat to counter excessive forces without external energy input, maintaining operational integrity and reducing the mass and technical requirements of the transmission system, thereby achieving weight reduction and cost savings.
Implementation Method 1
said elastic element having a determined stiffness and being prestressed such that, when an axial load exceeding a threshold load is applied to the drive body, said elastic element compresses and said at least one braking face of the drive body comes into contact with said at least one braking face of the frame
Implementation Method 2
said at least one braking face of the drive body comes into contact with said at least one braking face of the frame
Data Source
Figure 1
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AI summary
The invention relates to an aircraft seat comprising an actuator and a movement transmission device (22) comprising: - a frame (26) comprising at least one bearing face (34, 38) and one braking face (36, 40), - a drive body (28) capable of being rotated relative to the frame (26); the drive body comprising a bearing face (62, 65) and a braking face (55, 63), - an elastic element (30, 31) suitable for keeping the braking face of the drive body at a defined distance from the braking face of the frame, the elastic element having a determined stiffness and being prestressed such that, when an axial load greater than a threshold load is applied to the drive body, the braking face of the drive body comes into contact with the at least one braking face of the frame.