Worm-Screw Gear Shift Mechanism Without Cable Adjustment
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Solution Overview
Problem
Existing gear shift systems for mobility machines, such as bicycles, are complex, require many parts, and are difficult to manufacture and maintain, particularly due to the need for precise and regular adjustment of cable controls.
Innovation Solution
A gear shift device with a series of input and output pinions, a worm screw, and a shuttle that is displaced along the worm screw by a gear shift actuator, eliminating the need for cables and simplifying the gear shifting process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If cable control systems are used for gear shifting, then gear selection can be achieved, but the system becomes complex and requires precise regular adjustment
Solution Approach 1:
The patent removes the cable control system from the gear shifting mechanism, replacing it with a direct mechanical connection between the rotary handle and the shuttle via the worm screw. This extraction of the cable intermediary simplifies the system structure while maintaining gear selection functionality.
Solution Approach 2:
The worm screw acts as a new intermediary mechanism between the rotary handle and the shuttle, replacing the cable. This mediator provides both the necessary motion transmission and self-locking capability, reducing system complexity while ensuring reliable gear engagement.
2Ease of operation
If cable control systems are used for gear shifting, then gear selection can be achieved, but maintenance becomes difficult
Solution Approach 1:
By removing the cable control system, the patent eliminates the component that requires precise adjustment and regular maintenance. The direct mechanical connection through the worm screw is inherently more robust and requires less maintenance intervention.
3Ease of operation
If traditional gear shift systems are used, then gear shifting function is provided, but the system bulk is large
Solution Approach 1:
The patent combines multiple functions into the worm screw mechanism, which simultaneously serves as the control input transmission, the positioning mechanism, and the engagement actuator. This merging of functions reduces the overall system bulk while maintaining full gear shifting capability.
Solution Approach 2:
The shuttle is designed to surround the worm screw, with the input pinions arranged around the selection shaft. This nested arrangement allows compact packaging of multiple components in a space-efficient configuration, reducing system bulk.
4Ease of operation
If traditional gear shift systems are used, then gear shifting function is provided, but reliability is reduced
Solution Approach 1:
The worm screw serves as a reliable intermediary that provides inherent self-locking capability, preventing unintended gear changes. This mechanical intermediary ensures positive engagement and maintains reliable gear selection without the slippage or adjustment issues associated with cable systems.
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 provides a compact, reliable, and easy-to-maintain gear shift system that automates the gear shifting process, reducing the complexity and bulk of traditional systems while ensuring precise gear engagement.
Implementation Method 1
a worm screw (132) arranged so as to transform a rotational movement into a translational movement of the shuttle (155)
Implementation Method 2
the shuttle (155) accommodating at least one return member (152), in particular arranged so as to cooperate with at least one ball (151) of the selection shaft (200)
Data Source
AI summary
A gear shift device for a mobility machine has a plurality of gears between a first gear referred to as gear No. 1 and a top gear. The gear shift device includes a series of input pinions arranged so as to turn freely around a selection shaft with an axis X2, said selection shaft accommodating a worm screw and a shuttle. The gear shift device also includes a series of output pinions with an axis X3 that rotate conjointly with a hollow shaft a gear shift actuator arranged so as to displace the shuttle along the worm screw between a plurality of positions and to engage a selected gear. A mobility machine can include the gear shift device.