Mobility Gearshift Shuttle Guidance With Anti-Rotation Structure
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Solution Overview
Problem
Existing gearshift devices for mobility machines, such as bicycles, suffer from imperfectly guided shuttles, leading to inefficiencies and potential mechanical issues.
Innovation Solution
A gearshift device with a selection shaft, worm screw, and guide tube arrangement, featuring a rotation-blocking element and anti-rotation washer, ensures precise guidance and stability of the shuttle, using a guide tube formed by two blades and a rotation-blocking element with offset tabs to prevent rotation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a traditional shuttle system with pawls and input pinions is used, then gear selection is achieved, but the shuttle is imperfectly guided leading to mechanical issues
Solution Approach 1:
A guide tube is introduced as an intermediary component between the shuttle and the selection shaft. This guide tube properly guides the shuttle along the selection shaft, ensuring both reliable gear selection and smooth operation. The guide tube acts as a mediator that constrains the shuttle's movement path while allowing it to engage with the worm screw and pawls effectively.
Solution Approach 2:
The guide tube provides localized guidance only where needed - along the portion of the selection shaft where the shuttle travels. The guide tube is positioned to constrain the shuttle's radial movement while allowing axial movement, providing precise local control over the shuttle's path without affecting other parts of the mechanism.
2Manufacturing precision
If the guide tube is made longer to fully contain the worm screw, then guidance precision is improved, but device complexity increases
Solution Approach 1:
The guide tube serves multiple functions simultaneously: it guides the shuttle along the selection shaft, contains the worm screw, provides structural support, and helps position the rotation-blocking element. By making the guide tube fulfill several roles, the design achieves precise positioning without proportionally increasing complexity.
Solution Approach 2:
The guide tube is merged with the rotation-blocking element integration, where the guide tube's structure is designed to work in conjunction with the rotation-blocking element. The guide tube and rotation-blocking element together form an integrated system that prevents shuttle rotation while maintaining guidance, reducing overall device complexity compared to separate components.
3Measurement precision
If a rotation-blocking element is added to prevent shuttle rotation, then gear engagement accuracy is improved, but device complexity increases
Solution Approach 1:
The rotation-blocking function is segmented into a separate, dedicated element rather than being integrated into the guide tube or selection shaft. This rotation-blocking element is a distinct component with the specific function of preventing shuttle rotation, making the system easier to manufacture and assemble while ensuring accurate gear engagement.
Solution Approach 2:
The rotation-blocking element acts as an intermediary between the guide tube and the shuttle. It prevents the shuttle from rotating on the selection shaft by providing a mechanical constraint, thereby ensuring that the shuttle moves only in the intended axial direction for accurate gear engagement without requiring complex integration into other components.
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
Enhances the precision and stability of gear shifting, reducing mechanical wear and improving operational efficiency by preventing shuttle rotation and ensuring accurate gear engagement.
Implementation Method 1
a worm screw (21) and a nut (210) threaded onto the worm screw
Implementation Method 2
a guide tube (45) in which the worm screw is positioned
Implementation Method 3
one of the ends of the tube is inserted in a rotation-blocking element so that the shuttle can be prevented from rotating
Data Source
AI summary
A gear-shifting device for a mobility machine is disclosed herein. The gear-shifting device includes a selection shaft in which are arranged a shuttle, a worm screw, and a guide tube in which the worm screw is positioned.