Polyamide Spoke Structure for Low-Vibration Non-Pneumatic Wheels
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Solution Overview
Problem
Non-pneumatic tires face challenges in reducing noise, vibration, and impulse forces due to high stiffness rates when encountering obstacles, which is exacerbated by the limited effective length of spokes, leading to increased intrusivity and discomfort for vehicle operators.
Innovation Solution
The design incorporates V-shaped geometry spokes with pretension and high rigidity materials, such as polyamides with specific tensile modulus and fatigue resistance, allowing for a lower tangent stiffness and reduced effective length, thereby minimizing noise and vibration while maintaining load-carrying capacity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If spokes are constructed from low modulus material to reduce stiffness, then noise and vibration are reduced, but the effective length must be increased which is limited by the distance between hub and outer band
Solution Approach 1:
The patent changes the material parameter from low modulus to high modulus polyamide, and compensates by adjusting the geometric parameters (spoke thickness, width, and profile) to achieve the desired stiffness characteristics without increasing effective length
Solution Approach 2:
The patent uses polyamide as a composite material that provides high modulus properties while maintaining the ability to control stiffness through geometric design, resolving the contradiction between material stiffness and dimensional constraints
2Strength
If spokes are constructed from high modulus material to increase stiffness, then load carrying capacity is improved, but noise and vibration increase due to higher intrusivity
Solution Approach 1:
The patent applies local quality by varying the spoke profile and thickness distribution along the spoke length, creating regions of different stiffness that allow high load carrying capacity at the root while reducing intrusivity at the tip
Solution Approach 2:
The patent changes geometric parameters (thickness, width, profile shape) of the high modulus polyamide spokes to tune the stiffness characteristics, achieving both high strength and reduced noise/vibration
3Object-affected harmful factors
If spoke length is increased to reduce stiffness rate, then intrusivity is reduced, but the structural integrity and load distribution are compromised
Solution Approach 1:
The patent uses high modulus polyamide material that provides both the strength for structural integrity and the ability to control stiffness through geometric design, eliminating the need to increase length
Solution Approach 2:
The patent varies the local geometry of the spoke to create optimal stiffness distribution, maintaining structural integrity at the root while reducing intrusivity at the outer end
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 effectively reduces noise, vibration, and impulse forces by achieving a lower tangent stiffness and minimizing effective spoke length, enhancing the intrusivity characteristics of non-pneumatic wheels for both slow and fast-moving vehicles.
Implementation Method 1
Construction of spokes in traditional non-pneumatic tires from a low modulus material creates non-pneumatic tire spokes having the ability to absorb shock, vibration and reduce noise and impulse forces
Implementation Method 2
a compliant band with a ground contacting portion can be connected with a plurality of tension-transmitting, web-like elements (also referred to as 'spokes') extending radially from a center element or hub
Implementation Method 3
Tension of the spokes is countered by circumferential compression in the outer band of the wheel
Data Source
Figure 1
Figure 2~3
Figure 4
AI summary
A non-pneumatic wheel (10, 10') includes an outer band (400), a hub (100) and a plurality of spokes (300, 300') formed from a polyamide material. Each of the plurality of spokes is mounted having a pretension in the radial direction corresponding to a displacement under the design load of the wheel, the displacement being equal to or greater than a predetermined deflection of the outer band under normal operation. The plurality of spokes is made from a polyamide material having a conditioned tensile modulus between 600 MPa and 3000 MPa, an equilibrium moisture content of no more than 1.5 %, and a fatigue failure resistance that can withstand at least 1 million cycles.