Bonded Piston Seal Lip Geometry for Low Friction
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Solution Overview
Problem
Standard bonded piston seals experience high sliding friction due to increased pressure actuation, resulting in higher normal forces and sliding loads, which can lead to leakage and reduced lip integrity.
Innovation Solution
The solution involves reducing the pressure received area of the sealing lip and eliminating rubber material on the backside near the contact point, allowing the lip to flex more easily and reducing the normal force exerted on the running surface, thereby decreasing the sliding load.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the sealing lip is designed to be highly sensitive to pressure to ensure pressure-activation and prevent leakage, then sealing reliability is improved, but the normal force and sliding load increase
Solution Approach 1:
The sealing lip is designed with non-uniform thickness distribution, featuring a thinner region at the pressure received area and a thicker region at the backside. This local variation in geometry allows the lip to be highly responsive to pressure activation where needed while maintaining structural integrity and reducing overall material mass, thereby achieving reliable sealing with reduced normal force.
Solution Approach 2:
The invention changes the geometric parameters of the sealing lip, specifically the thickness distribution and the ratio between pressure received area and backside area. By optimizing these parameters, the lip achieves enhanced pressure sensitivity for reliable sealing activation while simultaneously reducing the normal force exerted on the sealing surface, thus resolving the contradiction between sealing reliability and friction reduction.
2Force
If rubber material is eliminated on the back side of the sealing lip near the contact point, then the static load and normal force are reduced, but lip integrity may be compromised
Solution Approach 1:
The sealing lip employs non-uniform thickness distribution with a thinner pressure received area and a thicker backside region. This local variation allows material to be strategically placed only where structurally necessary, reducing overall static load while maintaining lip integrity through optimized material distribution rather than uniform thickening.
Solution Approach 2:
The thicker backside region is designed in advance to provide structural support and maintain lip integrity before the seal is installed and pressurized. This preliminary structural reinforcement ensures the lip can withstand installation forces and maintain its shape during operation, preventing integrity issues that might arise from material reduction.
3Force
If the pressure received area is reduced, then the sliding load is decreased, but pressure activation sensitivity may be reduced
Solution Approach 1:
The invention optimizes the parameters of the pressure received area, including its size, shape, and thickness distribution. By carefully selecting these parameters, the lip achieves reduced sliding load through smaller contact area while maintaining adequate pressure activation sensitivity through optimized thickness and geometric configuration that enhances pressure response efficiency.
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 approach significantly reduces the sliding load and static load of the bonded piston seal, achieving a lower friction seal without compromising lip integrity or ease of assembly, as demonstrated by finite element analysis and testing.
Implementation Method 1
This allows the lip to flex onto the running surface (either stretch onto a shaft or compress into a bore) much more easily because there is much less material to manipulate. This greatly reduces lip normal force.
Data Source
AI summary
An annular seal for a low friction bonded piston seal is provided. The annular seal having a central axis and including an annular seal body symmetrically positioned about the central axis. The annular seal is integrally molded to the body and provides a lower seal lip body, and a top seal lip. The top seal lip including a first radial lip thickness T1 and a second radial lip thickness T2. A ratio between second radial lip thickness T2 to first radial lip thickness T1 is less than 1.00. The annular seal includes a radial lip height H, and a radial lip overall pressure received thickness T3. A ratio of radial lip height H to second radial lip thickness T2 is greater than or equal to 0.65. The radial lip overall pressure received thickness T3 is less than or equal to 0.8 mm. The first radial lip thickness T1 is less than or equal to 0.7 mm.