CFRP Vehicle Wheel Fastening with Conical Bushing
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Solution Overview
Problem
Vehicle wheels made entirely of carbon fiber reinforced plastic (CFRP) face increased manufacturing costs, and existing hybrid wheels with bolt-fastened rims and aluminum alloy spokes are prone to electrolytic corrosion due to external exposure to rainwater, leading to potential corrosion at the fastening portions.
Innovation Solution
A vehicle wheel design featuring a rim made of fiber-reinforced resin with a conical hollow portion, a bushing with a conical tube shape, and a male screw member that penetrates the rim's outer surface, engaging with a female screw hole on the spoke, all while keeping the male screw member inside the tire, thus preventing external exposure and reducing surface pressure to prevent electrolytic corrosion and creep phenomena.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the male screw member is externally exposed for fastening the rim and spoke, then the fastening function is achieved, but electrolytic corrosion occurs due to exposure to rainwater
Solution Approach 1:
The patent introduces a bushing as an intermediary component between the male screw member and the external environment. The bushing penetrates the rim wall and provides a protective barrier that prevents rainwater from directly contacting the male screw member and spoke, thereby eliminating electrolytic corrosion while maintaining the fastening function. The bushing acts as a mediator that isolates the metallic components from the corrosive external environment.
2Device complexity
If the male screw member head portion is small in diameter, then the fastening structure is compact, but the surface pressure on the rim increases causing creep phenomenon
Solution Approach 1:
The patent employs asymmetric design in the bushing structure, with a conical inner cavity that has a larger diameter at one end and a smaller diameter at the other. This asymmetric geometry allows the bushing to distribute the load from the male screw member head over a larger surface area of the rim, reducing surface pressure and preventing creep phenomenon. The asymmetric conical shape enables compact fastening structure while simultaneously providing adequate stress distribution.
3Reliability
If the opening of the conical hollow portion is small in diameter, then the bushing fits tightly in the rim, but the male screw member cannot be properly inserted
Solution Approach 1:
The patent utilizes a conical (curved) geometry for the inner cavity of the bushing instead of a cylindrical shape. The conical curvature allows the bushing to be inserted through the rim wall at an angle, with the larger diameter end entering first through the opening of the conical hollow portion. This curved geometry enables tight fitting of the bushing in the rim while simultaneously providing sufficient space for the male screw member to be properly inserted and engaged.
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 design effectively suppresses electrolytic corrosion and creep distortion by keeping the male screw member inside the tire and distributing stress evenly, reducing manufacturing costs and maintaining the wheel's structural integrity and air-tightness.
Implementation Method 1
This can suppress occurrence of the creep phenomenon in which a distortion increases as time passes when a stress is continuously applied to an object
Data Source
AI summary
The fastening through hole includes the conical hollow portion conically hollowed from the tube outer circumferential surface of the rim, the through hole penetrating the rim at a center portion of the conical hollow portion in a diametrical direction. The opening of the conical hollow portion on a side of the tube outer circumferential surface includes the conical tube having an external conical shape which is substantially the same as the conical hollow portion. The conical tube of the conical tube is set to be greater than a diameter of the head portion of the male screw member.