One-Piece Composite Bicycle Wheel With Z-Shaped Spokes
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Solution Overview
Problem
Existing cycle wheels face challenges in balancing light weight with sufficient mechanical strength and stability, especially under increased loads from electrically powered bicycles and cargo bikes. Additionally, there is a need to address the issues of material relaxation and creep in thermoplastic materials, and to improve heat removal or insulation for electronic components within the wheel.
Innovation Solution
A one-piece thermoplastic wheel with a fibre-reinforced or carbon nano-tube containing thermoplastic, featuring a Z-shaped cross-section for the spokes, which provides increased mechanical strength and flexibility. The wheel is produced using injection molding, allowing for efficient mass production and integration of metal or plastic inserts for enhanced stability and component mounting.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If material is added to increase mechanical strength, then the wheel can withstand higher loads, but the weight of the wheel increases
Solution Approach 1:
The patent employs fiber-reinforced thermoplastic composite materials, where fibers (such as glass, carbon, or aramid) are embedded in a thermoplastic matrix. This composite structure provides high mechanical strength-to-weight ratio, enabling the wheel to withstand loads while maintaining low weight. The fiber reinforcement specifically addresses the strength requirement without proportionally increasing weight.
Solution Approach 2:
The patent implements variable wall thickness and strategic material distribution within the wheel structure. Thicker sections are placed where stresses are highest (such as near the hub and rim), while thinner sections are used where less strength is required. This localized quality optimization ensures sufficient strength while minimizing overall material usage and weight.
2Weight of moving object
If the number of spokes is reduced to decrease weight, then the wheel becomes lighter, but the wheel strength and stability decrease
Solution Approach 1:
The use of fiber-reinforced thermoplastic composite materials provides exceptional strength-to-weight ratio, allowing the wheel to maintain high strength with fewer spokes. The composite material's inherent strength compensates for the reduced number of load-bearing elements, enabling a lighter wheel design that does not sacrifice structural integrity.
Solution Approach 2:
The patent changes the material parameters by using high-strength composite materials with optimized fiber orientation and content. This parameter change allows the structural geometry (number of spokes) to be reduced while maintaining strength, as the material itself provides enhanced load-bearing capacity per unit weight.
3Weight of moving object
If thermoplastic material is used to reduce weight, then the wheel becomes lighter and easier to manufacture, but the material exhibits relaxation and creep under load
Solution Approach 1:
The fiber reinforcement in the thermoplastic composite provides structural rigidity and resistance to creep and relaxation. The fibers act as a skeletal framework that maintains dimensional stability under sustained loads, compensating for the thermoplastic matrix's tendency to deform. This composite structure enables the wheel to maintain both low weight and high reliability.
Solution Approach 2:
The patent optimizes the local material composition and fiber orientation in critical stress areas to enhance resistance against creep and relaxation. By strategically placing reinforcement fibers in regions subjected to highest stresses, the design compensates for thermoplastic material limitations while maintaining overall weight efficiency.
4Strength
If fiber reinforced thermoplastic is used to increase strength, then the wheel can handle higher loads, but the manufacturing complexity and production difficulty increase
Solution Approach 1:
The patent replaces traditional mechanical assembly processes (joining separate metal components) with injection molding of integrated composite structures. The fiber-reinforced thermoplastic can be molded into complex three-dimensional shapes in a single manufacturing step, eliminating the need for separate machining, welding, or fastening operations required by metal components.
Solution Approach 2:
The patent utilizes the unique processing parameters of thermoplastic materials, which can be molded at relatively low temperatures compared to metal casting or forging. The fiber-reinforced thermoplastic composite allows for controlled fiber orientation during injection molding, enabling complex geometries to be produced with standard molding equipment, thus maintaining manufacturing ease while achieving high strength.
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 solution achieves a balance between light weight and high mechanical strength, enabling the wheel to withstand vertical and lateral loads, as well as torsional forces. The thermoplastic material's stability and the Z-profile design effectively manage stress and prevent deformation, ensuring the wheel meets safety standards and is suitable for various applications, including electric bicycles and cargo bikes.
Implementation Method 1
mould injection of fibre reinforced or carbon nano tubes containing thermoplastic
Implementation Method 2
mould injection of fibre reinforced or carbon nano tubes containing thermoplastic
Implementation Method 3
each of the plurality of spokes comprise a substantially Z-shaped cross section with a middle leg and a pair of outer legs
Implementation Method 4
integrally formed by mould injection of fibre reinforced or carbon nano tubes containing thermoplastic
Data Source
AI summary
The disclosure relates to a stable one piece wheel, which is particularly suitable for cycles having an increased system weight such as electrically powered bicycles or cargo bikes, and a method producing said vehicle wheel. Said vehicle wheel includes an annular portion, a plurality of spokes and a hub portion integrally formed by mould injection of fibre reinforced or carbo nano tubes containing thermoplastic, wherein each of the plurality of spokes comprise a substantially Z-shaped cross section with a middle leg and a pair of outer legs, wherein the angle enclosed by each of the pair of outer legs and the middle leg is greater than a right angle and wherein the length of the middle leg increases from the annular portion toward the hub portion.