Lubricant Injector Piston Seal Structure Against Pressure Extrusion
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Solution Overview
Problem
Existing lubricant injector piston seals fail due to fluid pressure causing seal material extrusion, leading to leakage and malfunction, as they are not effectively sealed between the piston head and the chamber wall.
Innovation Solution
A piston assembly with a polymeric seal featuring an annular, radially deflectable lip that engages with the chamber's inner cylindrical surface and end face, providing enhanced sealing pressure and preventing extrusion, coupled with a piston body and rod design that ensures proper alignment and sealing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a traditional seal design is used, then the seal material can be easily installed, but fluid pressure causes seal material extrusion leading to seal failure
Solution Approach 1:
The seal is divided into two functional parts: a radially deflectable annular lip for sealing against the chamber wall, and an axial end portion for engaging the chamber end face. This segmentation allows each part to perform its specific function effectively - the lip prevents circumferential leakage while the end portion prevents axial extrusion
Solution Approach 2:
The annular lip is designed to be radially deflectable, allowing it to dynamically adjust to pressure variations and maintain sealing contact with the chamber wall. This dynamic flexibility enables the seal to accommodate pressure changes without failing or extruding
2Reliability
If the seal engages tightly with the chamber wall to prevent leakage, then sealing performance improves, but the seal material is more prone to extrusion under fluid pressure
Solution Approach 1:
The sealing function is separated into two independent elements: the annular lip handles radial sealing against the chamber wall, while the axial end portion handles engagement with the end face. This division allows tight sealing without concentrating all sealing forces on a single structure that would be vulnerable to extrusion
Solution Approach 2:
The axial end portion acts as an intermediary that engages the chamber end face to provide axial support and positioning. This intermediary structure prevents the seal material from being directly subjected to axial extrusion forces while maintaining effective sealing contact
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 effectively prevents fluid leakage and ensures reliable displacement of the piston, maintaining seal integrity during both filling and ejecting operations, thus enhancing the performance and longevity of the lubricant injector.
Implementation Method 1
an annular, radially deflectable lip that engages with the chamber's inner cylindrical surface
Data Source
AI summary
A piston assembly is for a fluid delivery device, preferably a lubricant injector, the injector having a measuring chamber defined by an inner cylindrical surface and an axial end face, a flow port through the end face, and a central axis extending through the chamber. The piston assembly includes a piston body disposeable within the chamber so as to be linearly displaceable along the central axis. The piston body includes a cylindrical head, the head having first and second axial ends and an outer circumferential surface, and a rod extending axially from the second axial end of the piston head. A seal is coupled with the first axial end of the piston head and has an annular lip sealingly engageable with the chamber inner cylindrical surface and an axial end engageable with the chamber end face.