Bicycle Gearshift Chain Positioning for Multi-Step Shifting
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Solution Overview
Problem
Existing electronically servo-assisted bicycle gearshifts face challenges in executing multiple gear-shifting, particularly upward gear-shifting, due to the severe angle of the chain, which can result in traction loss and mechanical damage, limiting shifts to double or triple gear-shifting and posing risks to the rider's balance.
Innovation Solution
The solution involves actuating multiple gear-shifting by sequentially performing single gear-shifting steps, moving the chain from the current toothed wheel to an adjacent one, and repeating this process until the target toothed wheel is reached, with optional delays between steps to maintain chain engagement and reduce mechanical stress.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If multiple gear-shifting is executed by actuating the guide element for the chain over a large displacement, then the gear-shifting speed is improved, but the chain angle becomes severe causing traction loss and mechanical damage
Solution Approach 1:
The patent divides a multiple gear-shifting operation into a sequence of single gear-shifting steps. Instead of moving the guide element for the chain in one large displacement, the system performs multiple smaller displacements sequentially, each engaging an adjacent toothed wheel. This segmentation maintains proper chain angle throughout the transition, preventing traction loss and mechanical damage while still achieving the overall gear change.
2Productivity
If multiple gear-shifting is executed by actuating the guide element for the chain over a large displacement, then the gear-shifting efficiency is improved, but mechanical damage risk increases
Solution Approach 1:
The patent segments the gear-shifting process into controlled single-step transitions. Each step moves the guide element for the chain only enough to engage the next adjacent toothed wheel, rather than making a large single displacement. This reduces mechanical stress and damage risk while maintaining efficiency through automated sequential execution.
Solution Approach 2:
The electronic control unit plans and executes the sequence of gear-shifting steps in advance. Before initiating a multiple gear-shifting operation, the system determines the optimal sequence of intermediate toothed wheels to engage, ensuring that each preliminary action is properly executed before proceeding to the next step, thereby preventing mechanical damage.
3Stability of the object's composition
If single gear-shifting steps are performed sequentially with delays, then chain engagement stability is improved, but the total gear-shifting time increases
Solution Approach 1:
The patent employs periodic action by introducing controlled delays between sequential single gear-shifting steps. The electronic control unit manages the timing of each step, allowing the chain to stabilize on each intermediate toothed wheel before proceeding to the next. This periodic pause ensures stable chain engagement while the automated sequencing minimizes overall time loss.
Data Source
AI summary
An electronically servo-assisted gearshift actuates a multiple gear-shifting that moves a chain from a current toothed wheel to a target toothed wheel not immediately adjacent to the current toothed wheel in a gearshift group having at least three toothed wheels. Actuating the multiple gear-shifting takes several steps (i) actuating a single gear-shifting to move the chain to a toothed wheel immediately adjacent to the current toothed wheel in the gear-shifting direction, and (ii) repeating step (i) until the immediately adjacent toothed wheel is the target toothed wheel.