Actuator Coupling Device for Cabin Seat Torque Management
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Solution Overview
Problem
Aircraft passenger seats equipped with electrical actuators face challenges in ensuring sufficient stiffness and safety during critical phases, as the inertia of the actuators may not meet strength constraints, and the use of bolts for locking complicates control and alignment, leading to potential breakages and weight increase.
Innovation Solution
An actuator with a coupling device that transitions between two configurations: one for transmitting torque below a threshold and another for diverting torque to the frame when exceeding the threshold, utilizing a passive coupling mechanism with movable coupling members and lugs to manage torque distribution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If bolts are used to immobilize seat parts during critical flight phases, then seat stiffness and safety are improved, but device complexity and control difficulty increase
Solution Approach 1:
The coupling device automatically switches between coupling and decoupling configurations based on the torque threshold, without requiring external control signals or complex control systems. The system serves itself by using the torque magnitude itself as the triggering mechanism for configuration change.
Solution Approach 2:
The coupling device transitions from a static bolt-based locking system to a dynamic system that automatically adapts its configuration based on operational conditions. The coupling members can move between coupled and decoupled positions relative to the frame, enabling the system to respond dynamically to torque variations.
2Reliability
If bolts are used for locking seat elements, then reliability of locking is improved, but alignment issues may prevent proper engagement
Solution Approach 1:
The coupling device incorporates a threshold torque mechanism that prevents engagement when misalignment is detected (indicated by inability to reach threshold torque). This beforehand protection prevents unreliable locking due to misalignment, while still allowing reliable locking when proper alignment is achieved.
Solution Approach 2:
The system uses torque magnitude as a parameter to determine engagement status. By monitoring whether the torque reaches the predetermined threshold, the system can reliably determine if proper alignment and engagement have occurred, converting a positional alignment problem into a measurable torque parameter.
3Device complexity
If traditional coupling devices are used, then torque transmission is simple, but breakage risk increases under high torque
Solution Approach 1:
The coupling device transitions from a static torque transmission path to a dynamic system that can switch between two configurations: a first configuration for normal torque transmission and a second configuration for high torque protection. This dynamic adaptation prevents breakage by redirecting excessive torque away from the drive train.
Solution Approach 2:
The coupling members act as intermediaries between the upstream and downstream elements. When torque exceeds the threshold, these intermediary elements facilitate the switching to the second configuration, protecting the drive train from breakage while maintaining system functionality.
4Strength
If actuator inertia is increased to meet strength constraints, then safety during impact is improved, but weight increase occurs
Solution Approach 1:
The frame acts as an intermediary structure that absorbs and distributes impact forces during critical phases. By engaging the coupling device in the second configuration, the actuator leverages the frame's structural strength rather than relying solely on increased actuator inertia, avoiding unnecessary weight increase.
Solution Approach 2:
The coupling device is designed to switch to the protective configuration before catastrophic failure occurs. By anticipating high torque conditions and redirecting forces to the frame in advance, the system prevents breakage without requiring the actuator itself to be oversized for maximum impact resistance.
Data Source
AI summary
This actuator comprises a frame, a motor, an output shaft, and a drive train for driving the output shaft via the motor. The drive train comprises an upstream element, a downstream element, and a device for coupling the upstream element to the downstream element. Said coupling device has a first configuration for transmitting all of the torque exerted by one of the upstream and downstream elements on the coupling device to the other of the upstream and downstream elements when said torque is below a threshold torque, and a second configuration for diverting at least part of said torque exerted by one of the upstream and downstream elements on the coupling device to the frame when said torque is at least equal to the threshold torque.