Expandable Resilient Ring for Bicycle Bottom Bracket Alignment
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Solution Overview
Problem
Existing bottom bracket designs face challenges in achieving precise alignment and secure installation of large diameter bearings and spindles within bicycle frames, leading to potential misalignment, side-play, and premature bearing wear due to variable shell tolerances and machining precision issues.
Innovation Solution
A resilient, radially-expandable annular portion is integrated between bearing cups, which compresses and expands radially to apply force to the inner wall of the bottom bracket shell, ensuring proper alignment and secure locking of the bearing cups within the shell.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If large diameter bearings and spindles are used in traditional bottom bracket designs, then spindle strength and stiffness are improved, but bearing alignment precision deteriorates due to variable shell tolerances and machining precision issues
Solution Approach 1:
The resilient ring acts as an intermediary component between the bearing cups and the bottom bracket shell. It compensates for shell tolerance variations and machining precision issues by providing a compliant interface that maintains precise bearing alignment while allowing for manufacturing variations in the shell dimensions.
Solution Approach 2:
The resilient ring changes its physical state from a compressed condition during installation to an expanded condition in service, allowing it to adapt to varying shell tolerances. This parameter change enables the system to accommodate manufacturing variations while maintaining precise bearing alignment and supporting large diameter spindles.
2Reliability
If bearing cups are securely locked in the bottom bracket shell, then installation reliability is improved, but device complexity increases due to additional alignment and securing mechanisms
Solution Approach 1:
The resilient ring provides self-aligning and self-securing functionality. During installation, the ring compresses and expands to automatically align the bearing cups concentrically within the shell and lock them in place. This self-service mechanism eliminates the need for complex external alignment tools or additional securing components, achieving reliable installation through the inherent properties of the resilient material.
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
This solution improves bearing life by maintaining concentric alignment, reducing side-play, and securely installing the bottom bracket, while accommodating variable shell tolerances and manufacturing discrepancies.
Implementation Method 1
a resilient ring substantially coaxial with the left and right bearing cups and disposed intermediate the first annular abutment and the second annular abutment; wherein the bottom bracket is transitionable between: a first configuration, in which the resilient ring has a first outer diameter and the first annular abutment is spaced from the second annular abutment by a first distance, and a second configuration, in which the first annular abutment is spaced from the second annular abutment by a second distance smaller than the first distance and an axial force is applied to the resilient ring such that at least a portion of the resilient ring is expanded radially outward to a second outer diameter greater than the maximum outer diameter of the body portion of the bottom bracket
Data Source
AI summary
A bottom bracket for a bicycle may include a left bearing cup and a right bearing cup, the two bearing cups configured to be threaded together within a bottom bracket shell. Threading the bearing cups together may result in an axial force being applied to a resilient ring disposed on one of the bearing cups. This axial force may cause an outer diameter of the resilient ring to expand against an inner surface of the bottom bracket shell, thereby effectively locking the bottom bracket into the shell.