Airless Tire Spoke Bonding Strength via Surface Roughness
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Solution Overview
Problem
Airless tires face durability issues due to damage at the bonding portions between the spoke and tread ring or hub, which can lead to flaking and reduced riding comfort, especially when encountering road debris and curbstones.
Innovation Solution
The airless tire features a cylindrical tread ring and hub connected by a spoke formed from a cast molding body with high-polymer material, where the inner peripheral surface of the tread ring and outer peripheral surface of the hub are roughened to enhance the bonding strength using adhesive layers, improving the contact area and interlocking of the adhesive agent.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If adhesive bonding is used to connect the spoke to the tread ring and hub, then the tire structure can be assembled with separate components, but the bonding portion becomes vulnerable to damage from road debris and curbstones leading to flaking and reduced durability
Solution Approach 1:
The patent merges the spoke, tread ring, and hub into a single integrally-molded unitary structure, eliminating separate bonding portions that are vulnerable to damage. The spoke and hoops are formed as one continuous piece of elastomeric material, removing the weak adhesive bonding interfaces that occur with separate component assembly.
Solution Approach 2:
The patent uses a composite structure combining a stiff elastomeric material for the structural elements (spoke and hoops) with a rubber tread material for the outer hoop covering. This composite approach provides both structural integrity and durability while maintaining the benefits of integral molding.
2Device complexity
If a solid rubber structure is used for the airless tire, then the tire has simple construction, but the mass is large and shock absorption is inferior
Solution Approach 1:
The patent changes the material parameters by using a stiff, resilient elastomeric material with specific mechanical properties (tensile strength, elongation, hardness) that differ from conventional solid rubber. This allows the tire to maintain structural simplicity while reducing mass and improving shock absorption through the material's elastic properties.
Solution Approach 2:
The patent employs curved, cylindrical hoops and an arched spoke structure that utilize geometric form to enhance shock absorption. The curved geometry of the hoops and the arching shape of the spoke allow the structure to deform elastically under load, improving ride comfort while maintaining structural integrity.
3Strength
If the spoke is formed as a cast molding body with roughened surfaces on the hub and tread ring, then bonding strength is improved, but the manufacturing process becomes more complex
Solution Approach 1:
The patent eliminates the need for separate bonding processes by merging all components into a single integral molding operation. The roughened surfaces mentioned in the alternative embodiment are not needed because the integral structure has no bonding interfaces, thus avoiding the manufacturing complexity of surface preparation and adhesive application.
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 enhanced bonding strength inhibits damage growth and flaking between the spoke and tread ring or hub, thereby improving the tire's durability and resistance to road debris impacts.
Implementation Method 1
The inner peripheral surface of the tread ring and/or the outer peripheral surface of the hub is formed as a roughened surface having a surface roughness Ra (arithmetic roughness) ranging from 3 to 1000 μm or a surface roughness Rz (ten-point average roughness) ranging from 30 to 5000 μm
Implementation Method 2
an outer annular portion of which outer peripheral surface is bonded on an inner peripheral surface of the tread ring via a first adhesion layer made of adhesive agent
Data Source
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AI summary
The present invention increases the bonding strength between a spoke and a tread ring and/or between a spoke and a hub to improve durability. An airless tire provided with a tread ring, a hub, and a spoke, wherein the spoke is integrally provided with: an outer annul ar porti on of whi ch the outer peripheral surface is bonded to the inner peripheral surface of the tread ring via a first adhesion layer; an inner annular portion of which the inner peripheral surface is bonded to the outer peripheral surface of the hub via a second adhesion layer, and a spoke portion which couples the inner and outer annular portions. The inner peripheral surface of the tread ring and/or the outer peripheral surface of the hub is composed of a roughened surface having a surface roughness (Ra) (arithmetic average roughness) of 3-1000 µm or a surface roughness (Rz) (ten-point average roughness) of 30-5000 µm.