Single-Piece Composite Crankset with Metal Intermediate Rings
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Solution Overview
Problem
Existing one-piece cycle cranksets face challenges in using composite materials or hollow alloys due to issues with bearing support, abrasion resistance, and rigidity, leading to the necessity of multi-part designs with metal inserts for mechanical strength and weight reduction.
Innovation Solution
A one-piece cycle crankset design featuring cranks and a bottom bracket axle made of composite material or hollow light alloy, with intermediate rings fixed via polymerization or expansion for improved rigidity and reduced weight, and a split assembly ring with shim for easier assembly, allowing for thin walls and reduced weight without compromising mechanical strength.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Weight of moving object
If a one-piece crankset is made entirely of composite material to reduce weight, then weight is reduced, but the material cannot directly support bearings and lacks abrasion resistance
Solution Approach 1:
The crankset uses a composite structure combining a composite material crank body with metal intermediate rings. The composite material (carbon fiber reinforced plastic) provides weight reduction, while the metal intermediate rings provide bearing support and abrasion resistance. This composite approach resolves the contradiction by integrating materials with complementary properties.
Solution Approach 2:
The crankset is divided into functional segments: the composite crank body for weight reduction, and separate metal intermediate rings for mechanical support. This segmentation allows each component to be optimized for its specific function, with the intermediate rings acting as independent bearing support elements.
2Strength
If metal inserts are used in multi-part cranksets to ensure mechanical strength, then strength is improved, but weight increases and complexity increases
Solution Approach 1:
Instead of using metal inserts throughout the entire crankset, the invention applies metal intermediate rings only at the specific locations where bearing support is needed. This localized application of metal provides necessary mechanical strength at critical points while maintaining the overall lightweight composite structure.
3Weight of moving object
If a one-piece crankset is made of hollow light alloy to reduce weight, then weight is reduced, but the thin walls risk deformation under stress at bearing locations
Solution Approach 1:
The invention uses a composite material crank body with metal intermediate rings, providing both weight reduction and structural rigidity. The composite material allows for optimized wall thickness while the metal rings reinforce critical bearing areas.
Solution Approach 2:
The intermediate rings are integrated into the crankset structure during manufacturing, providing pre-reinforced bearing support locations. This preliminary structuring prevents deformation issues before the crankset is subjected to operational stresses.
4Strength
If intermediate rings are fixed on the crank axle to provide bearing support, then bearing support is improved, but the assembly process becomes more complex
Solution Approach 1:
The intermediate rings are designed to be self-retaining on the crank axle through interference fit or keyway mechanisms. This self-service design eliminates the need for additional fastening components and simplifies assembly, as the rings automatically secure themselves in position during installation.
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
Enables a lightweight, single-piece crankset with enhanced rigidity and reduced complexity, eliminating the need for additional parts and ensuring effective bearing support, while maintaining mechanical strength and ease of assembly.
Implementation Method 1
the said intermediate rings are fixed on the pedal axle by polymerization of said composite material of the bottom bracket axle following an expansion of said material
Implementation Method 2
the said intermediate rings are fixed on the crank spindle near a respective end of the latter to receive a respective bearing, characterized in that the said intermediate rings are fixed on the pedal axle by polymerization of said composite material of the bottom bracket axle following an expansion of said material
Data Source
Figure 1
Figure 2~3
Figure 4~5
AI summary
The crankset comprises a crank arm (1) connected to a second crank arm (2) by a bottom bracket axle (3), forming a single unit. The bottom bracket axle is housed within a bottom bracket tube (11) with two bearings (13, 14) positioned around the axle near its ends to allow rotation of the bottom bracket axle within the bottom bracket tube. A large sprocket (4, 5) for driving a chain is located near one end of the bottom bracket axle and is rotationally fixed to it. The crank arms (1, 2) and the bottom bracket axle (3) are made of a composite material or a hollow lightweight alloy. A first and second intermediate rings (15, 16) made of an abrasion-resistant material are fixed to the bottom bracket axle near one of its respective ends to receive a respective bearing.