Pressure Balanced Shaft Seal Assembly with Floating Stator
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Solution Overview
Problem
Existing shaft seal technologies fail to maintain effective sealing while allowing for shaft misalignment, often requiring a trade-off between tight clearance for sealing and loose clearance for adjustment, leading to inefficiencies and increased wear due to misalignment and product exposure.
Innovation Solution
A pressure-balanced shaft seal assembly with a floating stator and fixed stator, featuring O-ring channels, anti-rotation grooves and pins, and fluid return pathways, which allows for adjustable clearance and pressurization to maintain sealing integrity during radial, axial, and angular movements, using a sealing fluid to equalize pressure and isolate the seal from product contact.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If tight clearance is used between seal members and stationary member, then sealing efficiency is improved, but the seal cannot accommodate shaft misalignment
Solution Approach 1:
The patent employs a floating stator that can dynamically adjust its position relative to the shaft. The floating stator is supported on bearings that allow it to float axially and radially, enabling the seal to adapt to shaft misalignment while maintaining effective sealing clearance. This dynamic adjustment resolves the contradiction by making the seal geometry adaptable rather than fixed.
Solution Approach 2:
The seal assembly is divided into multiple independent components: a stationary member, a floating stator, and a rotating member. The floating stator acts as an intermediate element that can move independently to accommodate misalignment. This segmentation allows each component to perform its specific function while collectively solving the misalignment problem without compromising sealing efficiency.
2Adaptability or versatility
If loose clearance is used to accommodate shaft misalignment, then adaptability is improved, but sealing efficiency deteriorates
Solution Approach 1:
The floating stator dynamically maintains an optimal clearance distance from the shaft surface through its ability to float on bearings. This dynamic positioning ensures the clearance remains tight enough for effective sealing while allowing sufficient play to accommodate shaft misalignment, thus resolving the contradiction between loose and tight clearance requirements.
3Reliability
If contact seals are used to maintain tight clearance, then sealing efficiency is improved, but wear increases due to misalignment
Solution Approach 1:
The patent introduces a sealing fluid (liquid or vapor) as an intermediary between the floating stator and the shaft. This fluid creates a pressurized barrier that provides the sealing function without requiring direct mechanical contact between the seal surfaces. The intermediary fluid film eliminates wear while maintaining sealing effectiveness, even during shaft misalignment.
Solution Approach 2:
The patent employs hydraulic or pneumatic pressure of a sealing fluid to create the sealing barrier. The pressurized fluid is directed against the floating stator to prevent product leakage, replacing mechanical contact-based sealing with fluid pressure-based sealing. This approach maintains tight sealing clearance while eliminating the wear associated with contact seals.
4Reliability
If tight clearance is used to create pressure differential, then sealing performance is improved, but the seal cannot adjust to operational conditions
Solution Approach 1:
The floating stator's ability to move dynamically allows the seal to respond to varying operational conditions such as shaft misalignment, thermal expansion, and pressure changes. The pressurized sealing fluid adapts to these conditions while maintaining the pressure differential necessary for effective sealing, thus resolving the contradiction between tight clearance performance and operational adaptability.
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 enables improved sealing performance by allowing for misalignment adjustments while maintaining tight clearance, reducing wear, and effectively managing pressure differentials, thus enhancing the reliability and longevity of the shaft seal assembly.
Implementation Method 1
a sealing fluid to equalize pressure and isolate the seal from product contact
Implementation Method 2
Labyrinth seal for retaining lubrication solution within the bearing cavity
Data Source
Figure 1~2
Figure 3
Figure 3A~3B
AI summary
A pressure balanced shaft seal assembly that allows a seal to dynamically respond to angular or radial misalignment of a shaft is disclosed. The pressure balanced shaft seal assembly includes a fixed stator (2), a floating stator (4), and a labyrinth seal (3). In one embodiment, the floating stator (4) and labyrinth seal (3) are mounted within an annular groove formed in the fixed stator (2) such that the floating stator and labyrinth seal may move a predetermined amount in the radial direction with respect to the fixed stator. A spherical interface (11) between the labyrinth seal and floating stator may allow the labyrinth seal to pivot with respect to the floating stator during angular misalignment of a shaft around which the pressure balanced shaft seal assembly is mounted. A pressure balancing annular channel (46) formed in the floating stator allows pressurized seal fluid to balance the axial pressure exerted on the floating stator by the process fluid.