Coaxial Anti-Return Locking for Friction-Free Rotation Transmission

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Solution Overview

Problem

Existing rotation transmission devices often rely on friction, which hinders system operation and lacks robustness in stopping the output shaft, and require external energy for anti-return functions.

Innovation Solution

A mechanical anti-return device with a cam-profiled locking element that radially moves between locking and unlocking positions, utilizing a shoulder on the input shaft to rotate the output shaft and an elastic return mechanism for robust and compact operation, allowing simultaneous rotational drive and unlocking with minimal input shaft rotation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If friction-based mechanisms are used for rotation transmission, then the device can transmit rotational motion, but the system operation is hindered and robust rotational locking cannot be achieved

Engineering Contradiction:
Improverobust rotational lockingVSAvoidfriction hindering operation
Core Design Contradiction:
ReliabilityVSObject-generated harmful factors

Solution Approach 1:

The patent replaces friction-based mechanical transmission with a positive engagement locking mechanism. A locking element with cam surfaces engages directly with the output shaft through radial translation, providing robust rotational locking without relying on friction. This substitution eliminates the harmful friction effects while maintaining reliable rotation transmission control.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

2Reliability

If external power source is used for back-stop function, then the anti-return function can be achieved, but the device complexity and energy requirement increase

Engineering Contradiction:
Improveanti-return functionVSAvoidexternal power source requirement
Core Design Contradiction:
ReliabilityVSUse of energy by moving object

Solution Approach 1:

The locking element is designed to automatically engage and disengage based on the rotational direction of the output shaft, without requiring external power. The cam surfaces and elastic return means create a self-actuating system that provides anti-return function passively, eliminating the need for external power sources while maintaining reliable operation.

Inventive Principle:
Principle #25Self-service

3Ease of operation

If locking element is moved radially for switching positions, then the unlocking function is achieved, but the device complexity increases

Engineering Contradiction:
Improveunlocking functionVSAvoidlocking mechanism structure
Core Design Contradiction:
Ease of operationVSDevice complexity

Solution Approach 1:

The patent combines the locking element's radial translation movement with the rotational motion of the output shaft. The cam surfaces are integrated into the locking element itself, which translates radially to engage or disengage the locking function. This merging of functions reduces the need for separate actuating mechanisms, thereby simplifying the overall device structure while maintaining ease of operation.

Inventive Principle:
Principle #5Merging (Combining)

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 device achieves robust, adaptable, and compact one-way rotational movement transmission without external energy, ensuring efficient operation and quick unlocking of the output shaft with minimal input rotation.

Implementation Method 1

a cam having a profile adapted to radially move the locking element during a rotation of the input shaft

Methodology Applied
Scientific EffectCam mechanism: Cam

Implementation Method 2

elastic return means for the locking element, working in compression to push said locking element towards the axis of the shafts against the cam or, where applicable, against the unlocking key

Methodology Applied
Scientific EffectElastic force: Elasticity

Implementation Method 3

the elastic return means in the locked position include a spring linked to the frame

Methodology Applied
Scientific EffectSpring force: Spring

Data Source

PatentEP4025799B1Anti-return device for rotation transmission
Publication Date: 2024.08.14 SAFRAN ELECTRONICS & DEFENSE (FR)
  • EP4025799B1 patent drawingFigure 1A~1B
  • EP4025799B1 patent drawingFigure 2A~2B
  • EP4025799B1 patent drawingFigure 2C~3A

AI summary

Said non-return device for coaxial rotation transmission comprises two coaxial input (2) and output (3) shafts, a frame (4) for guiding the rotation of the shafts (2, 3), a locking element (5) urged in radial translation through a channel (31) of the output shaft (3) between a radial locking position in which the locking element (5) projects from the channel (31) so as to prevent a rotation of the output shaft (2) by abutting against the frame (4) and a radial unlocking position in which the locking element (5) is retracted so as to allow axial rotation of the output shaft (3), the input shaft (2) comprising means for radially switching the locking element (21) between the locking and unlocking positions thereof.