Bicycle Bottom Bracket Sealing Gasket Lip Dynamics
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Solution Overview
Problem
Existing bicycle bottom bracket designs fail to effectively protect rolling bearings from water infiltration, especially during pressurized washing, leading to potential leaks and decreased efficiency due to increased friction from additional gaskets or complex installation issues with auxiliary rings.
Innovation Solution
A sealing gasket with a first lip in constant fluid-tight contact with the central pin and a second lip that moves radially inward upon deformation to enhance sealing, minimizing friction and preventing water infiltration, is used, eliminating the need for additional labyrinthine structures and simplifying installation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If multiple gaskets are used to ensure fluid-tight seal, then sealing effectiveness is improved, but friction increases and efficiency decreases
Solution Approach 1:
The sealing gasket is divided into two functional lips: a first lip that maintains constant fluid-tight contact with the central pin, and a second lip that activates only under pressurized conditions. This segmentation allows each lip to perform its specific function optimally - the first lip provides continuous sealing with minimal friction, while the second lip engages only when needed to block pressurized water, thus avoiding continuous friction loss.
Solution Approach 2:
The second lip of the sealing gasket is designed to be dynamically movable between two positions: a first position where it maintains fluid-tight contact with the central pin under normal conditions, and a second position where it moves away from the pin when pressurized water acts upon it. This dynamic behavior allows the seal to adapt to different operating conditions, providing effective sealing during washing while minimizing friction during normal pedaling.
2Reliability
If auxiliary rings with labyrinths are added to prevent water infiltration, then sealing effectiveness is improved, but device complexity increases
Solution Approach 1:
The invention merges the sealing function and the pressurized-water-response function into a single integrated sealing gasket component with two lips. This eliminates the need for separate auxiliary rings, labyrinths, and multiple gaskets that would otherwise be required to achieve the same protective effect, thereby simplifying the overall structure while maintaining sealing effectiveness.
Solution Approach 2:
The sealing gasket performs multiple functions: it provides continuous fluid-tight sealing during normal operation through the first lip, and it automatically responds to pressurized water by activating the second lip to enhance sealing. This multi-functionality replaces what would traditionally require multiple separate components (labyrinths, auxiliary rings, multiple gaskets), thereby reducing device complexity.
3Reliability
If auxiliary rings are installed to create labyrinth seal, then sealing effectiveness is improved, but installation difficulty increases
Solution Approach 1:
The invention combines what would traditionally be separate components (auxiliary rings, labyrinths, multiple gaskets) into a single integrated sealing gasket assembly. This unified structure is designed to be installed as one component between the cap and the rolling bearing, significantly simplifying the installation process compared to assembling multiple separate sealing elements.
4Reliability
If the gasket is made fluid-tight against the pin, then sealing effectiveness is improved, but friction increases
Solution Approach 1:
The sealing gasket is segmented into two lips with different functions: the first lip maintains constant fluid-tight contact with the central pin to prevent dust and dirt infiltration, while the second lip provides sealing only when activated by pressurized water. This segmentation allows the gasket to achieve effective sealing without requiring both lips to be in constant contact, thereby minimizing friction during normal operation.
Solution Approach 2:
The second lip is designed with dynamic contact characteristics: it maintains fluid-tight contact with the central pin only when pressurized water acts upon it, and remains disengaged during normal operation. This dynamic behavior reduces friction loss during pedaling while ensuring effective sealing when needed, resolving the contradiction between sealing effectiveness and friction.
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 fluid-tight seal against water and mud, maintaining pedaling efficiency by minimizing friction during normal use and effectively preventing water infiltration even under pressurized conditions, while simplifying the assembly process.
Implementation Method 1
said sealing gasket being elastically deformable between an undeformed condition and a deformed condition; wherein when the sealing gasket passes from the undeformed condition to the deformed condition, said second lip moves from a more outer radial position to a more inner radial position
Data Source
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AI summary
The invention relates to a bottom bracket (1) for bicycles comprising a central pin (2), a first adapter (8) radially outer with respect to said central pin (2) and intended to be associated with a box (102) for housing the bottom bracket, a first rolling bearing (6) radially arranged between said central pin (2) and said first adapter (8), a sealing gasket (30) arranged in axially outer position with respect to said first rolling bearing (6), radially outer with respect to said central pin (2) and directly exposed to the outside. The sealing gasket (30) comprises a first axially outer end (34) provided with a first lip (31) and a second lip (32) axially more inner with respect to the first lip (31), said first lip (31) being in constant fluid-tight relationship with said central pin (2). When the sealing gasket (30) is deformed, said second lip (32) moves from a more outer radial position, in which the second lip (32) is radially outer with respect to the first lip (31) and in which the second lip (32) does not exert a fluid-tight seal on said central pin (2), to a more inner radial position, in which the second lip (32) is in fluid-tight relationship with said central pin (2).