Bicycle Bottom Bracket Assembly with Nested Resin Bearings
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Solution Overview
Problem
Conventional bicycle bottom bracket assemblies are heavy and require threading of the bicycle frame ends due to external bearing placement, limiting design freedom and increasing weight.
Innovation Solution
The bicycle bottom bracket assembly features non-metallic bearing support members press-fitted into the bicycle frame, allowing bearings to be positioned axially inwardly, eliminating the need for threading and enabling a longer frame length, with resin housings providing weight savings and reduced noise.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If bearings are located outside of the cylindrical hanger part, then the bottom bracket assembly can be assembled, but the axial length of the hanger part must be made small and the assembly becomes heavy
Solution Approach 1:
The bearing support member is inserted into the cylindrical hanger part, and the bearing is housed within the bearing support member. This nested arrangement allows the bearing to be positioned within the hanger part's axial length rather than extending outside, reducing the required hanger part length and overall assembly weight while maintaining proper bearing support and crank axle rotation.
2Reliability
If metallic axle support housings are screwed into the hanger part, then the bearings can be supported, but threading is required and weight increases
Solution Approach 1:
The invention extracts the threading requirement from the hanger part by using a press-fit bearing support member that is inserted into the hanger part without requiring threaded holes. The bearing support member provides sufficient radial and axial support for the bearing through its press-fit connection and internal bearing housing structure, eliminating the need for complex threading operations on the hanger part.
Solution Approach 2:
The bearing support member acts as an intermediary component between the hanger part and the bearing. It provides the necessary support functions for the bearing while having a simple press-fit connection to the hanger part, avoiding the need for threading in the hanger part itself and reducing overall assembly complexity.
3Ease of operation
If bearings are positioned outside the hanger part, then assembly is simpler, but the frame length is limited and design freedom is reduced
Solution Approach 1:
By nesting the bearing support member and bearing within the hanger part, the invention allows the hanger part to be made longer without increasing the overall assembly length. This provides greater design freedom for frame geometry and component placement while maintaining assembly simplicity through the integrated nested structure.
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 design results in a lighter, more versatile bottom bracket assembly with reduced noise during pedaling, allowing for increased design freedom and improved structural integrity without the need for threaded ends.
Implementation Method 1
first and second bearing support members are press-fitted into the first and second open ends of the hanger part
Data Source
Figure 1~2
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AI summary
A bicycle bottom bracket assembly (50) is provided with a pair of bearing support members (55,56), and a pair of axle bearings (58,59) so that the bottom bracket assembly (50) is configured and arranged to be mounted into a hanger part (40) of a bicycle frame. The hanger part has opposite open ends. The bearing support members (55,56) are press-fitted into opposite open ends of the hanger part (40). The bearings (58,59) are retained in the bearing support members (55,56) such that the bearings are disposed inside of the hanger part (40) with outer races (58b,59b) of each of the bearings engaging one of the bearing support members (55,56). A crank axle (54) is rotatably supported within the hanger part (40) by inner races (58a,59a) of the bearings (58,59) with a first axial end portion of the crank axle (54) being disposed at one end of the hanger part and a second axial end portion of the crank axle (54) being disposed at the other end of the hanger part (40).