Non-pneumatic Wheel Tread with Localized Rubber Modulus
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Solution Overview
Problem
The non-pneumatic wheel's weld strength between the outer tube body and connection members is lower than other portions, making it prone to damage under load, particularly when stress is transferred from the tread member to the outer tube body.
Innovation Solution
The wheel design incorporates a base rubber portion with lower rigidity positioned between connection members and a cap rubber portion with higher rigidity, both extending along the radial direction of the outer tube body, to disperse stress and enhance weld protection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the outer tube body and connection members are integrally formed by injection molding with molding material injected from the connection member side toward the outer tube body side, then the manufacturing efficiency is improved, but the weld strength on the outer tube body becomes lower than other portions
Solution Approach 1:
The tread member is designed with non-uniform rubber composition, specifically with a higher proportion of soft rubber (lower modulus) at the portion contacting the outer tube body compared to other portions. This local differentiation in material properties allows the contact area to have better stress distribution and welding characteristics, while maintaining overall structural integrity and manufacturing efficiency through integral molding.
2Ease of manufacture
If the tread member is made with uniform rubber composition, then the manufacturing process is simplified, but the stress distribution on the outer tube body becomes uneven causing weld damage
Solution Approach 1:
The tread member incorporates a gradient rubber composition where the ratio of soft rubber to hard rubber varies by location. The portion contacting the outer tube body has a higher soft rubber content (lower modulus) for better stress distribution and welding, while other portions have higher hard rubber content for durability. This localized material optimization improves weld reliability without significantly complicating the manufacturing process.
3Stability of the object's composition
If the tread member has high rigidity, then the wheel structure is more stable, but the stress concentration on the outer tube body increases making it prone to damage
Solution Approach 1:
The tread member uses differentiated rubber composition with lower modulus (softer) material at the contact portion with the outer tube body to reduce stress concentration and prevent weld damage. Other portions of the tread member use higher modulus (harder) rubber to maintain overall wheel stability and structural rigidity. This spatial variation in material properties resolves the contradiction between local stress reduction and global stability.
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 configuration effectively disperses stress, improving the wheel's strength, wear resistance, and impact resistance, while maintaining driving stability and increasing the driving distance before failure.
Implementation Method 1
the at least one base rubber portion is disposed on an outer peripheral surface of the outer tube body, extending at least along a radial direction of the outer tube body and is positioned between outer end portions of the connection members adjacent to each other in the wheel peripheral direction, characterised in that rigidity of the base rubber portion is lower than rigidity of the cap rubber portion
Data Source
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AI summary
There is provided a non-pneumatic tire (1) including: an attachment body (11) that is attached to an axle; a ring-shaped body (13) that surrounds the attachment body (11) from an outside in a tire radial direction, a plurality of connection members (15) that are disposed between the attachment body (11) and the ring-shaped body (13) along a tire peripheral direction and connect the attachment body (11) and the ring-shaped body (13) to each other, and a cylindrical tread member (16) that is externally mounted on the ring-shaped body (13), in which the ring-shaped body (13) and the connection member (15) are integrally formed by a injection molding in which a molding material is injected from the connection member (15) side toward the ring-shaped body (13) side, in which the tread member (16) includes a base rubber portion (41) that is positioned at an inside in the tire radial direction and a cap rubber portion (42) that is positioned at an outside of the base rubber portion (41) in the tire radial direction, in which rigidity of the base rubber portion (41) is lower than rigidity of the cap rubber portion (42), and in which the base rubber portion (41) is disposed at least in a portion positioned between the connection members (15) adjacent to each other in the tire peripheral direction in the ring-shaped body (13).