Mechanical Pump Seal Using O-Rings to Prevent Shaft Fret Damage
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Solution Overview
Problem
Fret damage on pump shaft sleeves caused by Teflon U-cups leads to leakage issues in mechanical seal assemblies, as the U-cups inflate and deflate under pressure, damaging the sleeve and allowing gas leakage.
Innovation Solution
The use of standard O-rings, such as Kalrez brand materials, in a mechanical seal assembly that repositions the sealing area on the shaft sleeve, allowing for reuse of damaged sleeves without modifications, and incorporating a spring assembly and seal elements to maintain a secure seal.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If Teflon U-cups are used in mechanical seal assemblies, then sealing capability is improved, but fret damage occurs on the shaft sleeve causing leakage
Solution Approach 1:
The patent removes the Teflon U-cup component from the mechanical seal assembly and replaces it with an O-ring sealing system. This extraction eliminates the source of fret damage while maintaining sealing functionality through the O-ring that seals against the shaft sleeve without causing scratches or wear.
Solution Approach 2:
The patent changes the sealing mechanism from a U-cup design to an O-ring design, altering the material interaction parameters. The O-ring uses different material properties and sealing mechanics that prevent the scratching and fret damage caused by the U-cup's movement and inflation/deflation cycles.
2Ease of manufacture
If standard O-rings are used instead of Teflon seals, then ease of manufacture and availability is improved, but sealing performance under high pressure may be compromised
Solution Approach 1:
The patent employs standard O-rings that can be sourced from any rubber or synthetic rubber manufacturer, making the sealing system universal and easily manufacturable. The O-ring design accommodates various material options (Kalrez®, generic equivalents) while maintaining consistent sealing performance through the same geometric configuration and installation method.
3Ease of repair
If the sealing area is repositioned on the shaft sleeve, then reuse of damaged sleeves is enabled, but device complexity increases
Solution Approach 1:
The patent segments the sealing function from the shaft sleeve by using an O-ring that seals against a specific portion of the sleeve. This allows the sealing area to be repositioned or replaced independently, enabling reuse of damaged sleeves by installing the O-ring at a different location on the same sleeve without requiring sleeve replacement or modification.
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
Enables the reuse of fret-damaged seal sleeves and prevents gas leakage by utilizing O-rings to create a reliable seal without requiring modifications to the existing seal sleeve or cartridge, providing a field-installable pump seal repair kit.
Implementation Method 1
a spring assembly that biases the seal elements together, the spring assembly having an open center that receives the sleeve and shaft
Implementation Method 2
The use of standard O-rings, such as Kalrez brand materials, in a mechanical seal assembly that repositions the sealing area on the shaft sleeve
Data Source
AI summary
An improved mechanical seal and repair method can be used with mechanical pump seal assemblies. The improved seal utilizes rotating and non-rotating sections of improved configuration, each of which can form a seal using a standard size carbon-face O-ring. The mechanical seal can be in the form of replacement parts that replace the old parts without modifications to the overall seal and assembly.