Screw-Nut Transmission Brake for Bidirectional Crash Load Absorption
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Solution Overview
Problem
Existing seat drive systems in aircraft face challenges with wear and breakage due to crash-type loads and sudden stops, leading to overdesign and increased manufacturing costs and weight.
Innovation Solution
A transmission device comprising a screw, nut, housing, elastic members, and axial stops that dissipate axial forces through the housing, reducing wear and allowing for a two-way brake capable of absorbing forces in both directions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the mechanical parts of the drive system are overdesigned to support crash-type loads and sudden stops, then the reliability and strength are improved, but the manufacturing cost and weight increase
Solution Approach 1:
The patent introduces a brake device with friction elements positioned beforehand to absorb axial forces during crash-type loads and sudden stops. The friction elements are pre-configured to engage when excessive forces occur, cushioning the mechanical parts from damage without requiring them to be overdesigned for these extreme conditions.
Solution Approach 2:
The brake device acts as an intermediary between the drive system mechanical parts and the extreme loads. The friction elements mediate the force transmission, absorbing axial forces through friction before they reach the drive system components, thereby protecting them from wear and breakage without requiring overdesign.
2Reliability
If a one-way brake is used to absorb axial forces in one direction, then the protection against wear and breakage is improved, but the device complexity increases due to requiring two variants for bidirectional operation
Solution Approach 1:
The brake device is designed with friction elements that can absorb axial forces in both directions of rotation. By configuring the friction elements to engage with the threaded rod regardless of rotation direction, a single brake variant provides bidirectional protection, eliminating the need for two separate one-way brake variants and reducing device complexity.
Solution Approach 2:
Instead of using two separate one-way brakes oriented in different directions, the invention inverts the approach by designing a single brake where the friction elements are positioned to engage with the threaded rod from both sides or are configured to engage regardless of rotation direction. This single device performs the function of both one-way brakes simultaneously.
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
The solution reduces the risk of wear and fracture without overdesigning the device, while also enabling a two-way brake that can handle seat rebound forces, improving safety and reducing costs.
Implementation Method 1
the first elastic member being able to be deformed independently of the second elastic member under the effect of a first axial force oriented in a first direction and applied by the first assembly on the first elastic member, so as to reduce the first axial clearance
Implementation Method 2
the second elastic member being able to be deformed independently of the first elastic member under the effect of a second axial force oriented in a second direction opposite to the first direction and applied by the first assembly on the second elastic member
Implementation Method 3
based on a phenomenon of friction between several parts of the brake, allows stopping the actuator in the event of a load with significant axial force
Data Source
AI summary
A transmission device for transmitting a movement includes a screw extending along an axis, a nut, a housing, a first elastic member, a second elastic member,—a first assembly, a second assembly, a first axial stop, and a second axial stop. The first elastic member is able to be deformed independently of the second elastic member under the effect of a first axial force, and the second elastic member is able to be deformed independently of the first elastic member under the effect of a second axial force which exceeds a second threshold.