Bicycle Crank Axle Splined Coupling Assembly
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Solution Overview
Problem
Conventional bicycle crank assemblies are difficult to assemble due to complex and time-consuming processes, often requiring precise alignment and securement of crank arms to the crank axle.
Innovation Solution
A bicycle crank assembly design featuring a crank axle with splined end portions that provide a non-rotatable coupling to the crank arms, allowing for easy assembly through interference fits and the use of a fixing bolt, ensuring secure attachment without the need for extensive alignment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional crank arm securement methods are used, then reliable connection is achieved, but assembly process becomes complex and time-consuming
Solution Approach 1:
The connection interface is segmented into complementary splined features on the crank arm and corresponding recesses on the crank axle, allowing for modular assembly and simplified alignment
Solution Approach 2:
The interference fit between the crank arm bore and crank axle, combined with the splined interface, creates a self-aligning and self-securing connection that automatically positions components correctly during assembly
2Stability of the object's composition
If conventional securement methods are used, then connection stability is achieved, but assembly difficulty increases
Solution Approach 1:
The interference fit and splined interface work together to create a self-aligning connection that automatically positions components correctly during assembly, eliminating the need for complex alignment procedures
Solution Approach 2:
The design replaces complex mechanical fastening systems with a simplified interference fit and spline engagement mechanism that achieves both stability and ease of assembly
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 design simplifies the assembly process by providing a secure and stable connection between the crank arms and axle, reducing assembly time and ensuring reliable operation.
Implementation Method 1
The first end portion of the crank axle is attached to the first crank arm by adhesive
Implementation Method 2
The crank axle is mounted in the first axle mounting opening of the first crank arm with an interference fit therebetween
Data Source
AI summary
A bicycle crank axle assembly has first and second crank arms that are attached to opposite ends of a crank axle. The ends of the crank axle are non-rotatably disposed in axle mounting openings of the first and second crank arms. A first end of the crank axle has at least one axially extending first spline that protrudes radially outward from an outer peripheral surface of its middle body portion. The at least one axially extending first spline non-rotatably couples the crank axle to the first crank arm and prevents outward axial movement of the first crank arm away from the second crank arm. The second end portion of the crank axle has at least one recess that extend radially inward with respect to the outer peripheral surface of the middle body portion to form at least one axially extending second spline.