Bicycle Bottom Bracket Sealing Structure for Water Ingress Prevention
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Solution Overview
Problem
Conventional bicycle bottom bracket assemblies fail to effectively prevent water and contaminants from reaching the bearing units, leading to potential damage and reduced performance.
Innovation Solution
A bicycle bottom bracket assembly featuring a support member with a hanger mounting structure and a bearing mounting structure, combined with a sealing structure that includes elastomeric seal members and auxiliary covers to create a watertight seal, preventing water ingress and reducing rotational torque.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional dust tube is provided to prevent contamination, then water and contaminants are blocked from intruding into the bearing units, but the sealing effectiveness is insufficient and water still reaches the bearing units
Solution Approach 1:
The sealing structure is divided into multiple components: a dust tube, a seal member with lip, and an auxiliary cover. Each component performs a specific sealing function, creating multiple barriers against water ingress. The seal member's lip specifically contacts the inner race to prevent water entry, while the auxiliary cover provides additional protection at the bearing unit opening.
Solution Approach 2:
The seal member acts as an intermediary element between the dust tube and the bearing unit. Its lip extends to contact the inner race, creating an additional sealing interface that bridges the gap between the dust tube sealing and the bearing unit protection, effectively blocking water pathways.
2Reliability
If a seal structure is added to prevent water ingress, then bearing unit protection is improved, but rotational torque increases due to seal friction
Solution Approach 1:
The seal member is made of elastomeric material, a flexible substance that can deform elastically. This flexibility allows the seal lip to conform to the inner race surface while maintaining minimal contact pressure, effective sealing with reduced friction compared to rigid seal materials.
Solution Approach 2:
The seal member's elastomeric properties and the controlled contact between the lip and inner race create a balance between sealing effectiveness and friction. The material properties and contact parameters are optimized to provide sufficient sealing force while minimizing rotational resistance.
3Reliability
If multiple seal components are added to improve sealing, then water protection is enhanced, but device complexity increases
Solution Approach 1:
The auxiliary cover integrates multiple functions: it covers the bearing unit opening, provides a mounting surface for the seal member, and works with the dust tube to create a complete sealing system. This merging of functions into a single component reduces the number of separate parts needed while maintaining comprehensive protection.
Solution Approach 2:
The auxiliary cover serves multiple purposes: structural support for the sealing components, additional protective barrier, and integration element that connects the dust tube and seal member assembly to the bottom bracket housing. This multi-functionality reduces overall system complexity.
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 provides a reliable sealing structure that effectively prevents water and contaminants from reaching the bearing units, enhancing durability and reducing rotational torque, thus improving the overall performance and longevity of the bicycle bottom bracket.
Implementation Method 1
The seal member has a proximal end fixed to the support member and a distal end slidably contacting the inner race of the bearing unit
Implementation Method 2
a distal end slidably contacting the inner race of the bearing unit
Data Source
Figure 1
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AI summary
A bicycle bottom bracket assembly (12) is provided with a support member (26, 28), a bearing unit (30, 32) and a seal member (34, 36). The support member (34, 36) includes a hanger mounting structure (46) and a bearing mounting structure (48, 58). The bearing unit (30, 32) includes an outer race (80), an inner race (82) and at least one roller element (74)disposed between the outer and inner races. The outer race (80) is fixed to the bearing mounting structure (48, 58)of the support member (26, 28). The seal member (34, 36) has a proximal end (51a, 52a) fixed to the support member (26, 28) and a distal end (51b, 52b) slidably contacting the inner race (82) of the bearing unit (30, 32).