Flexible Sealing Membrane for High-Pressure Rotary Shaft Seals

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Solution Overview

Problem

Mechanical seals in rotary shaft equipment face challenges with excessive leakage due to frictional wear and axial movement, leading to seal failure at high pressures, as existing biasing mechanisms fail to effectively counteract closing forces and maintain a pressure-tight seal.

Innovation Solution

A flexible sealing membrane with a radially extending outer portion and a thinner inner portion, supported by an annular carrier and biasing mechanism, allows for axial movement while maintaining a pressure-tight seal, reducing torque stress and preventing collapse under high pressures.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Use of energy by moving object

If a non-pusher seal with elastomeric bellows is used to reduce torque stress, then torque stress on the bellows is reduced, but at high pressures the shaft translates axially causing the elastomer to rigidly collapse and preventing the bellows from counteracting closing forces

Engineering Contradiction:

Improvetorque stressVSAvoidseal performance at high pressure

Core Design Contradiction:

Use of energy by moving objectVSReliability

Solution Approach 1:

The patent employs a flexible membrane made of elastomeric material that can axially deflect to accommodate shaft movement. This membrane replaces the rigid elastomeric bellows and provides the necessary flexibility to maintain sealing at high pressures while allowing axial translation of the shaft without collapse.

Inventive Principle:

Principle #30Flexible shells and thin films

Solution Approach 2:

The patent changes the structural parameters of the sealing element by transitioning from a bellows configuration to a membrane configuration. This allows the sealing element to maintain its flexibility and sealing capability under high pressure conditions where the original bellows would collapse.

Inventive Principle:

Principle #35Parameter changes

2Reliability

If a pusher seal assembly with dynamic secondary seal is used to provide sealing between shaft and seal members, then sealing is provided, but axial movement relative to the shaft causes fretting or shredding of the secondary seal due to friction

Engineering Contradiction:

Improvesealing capabilityVSAvoidservice life of secondary seal

Core Design Contradiction:

ReliabilityVSDuration of action of moving object

Solution Approach 1:

The patent extracts the dynamic secondary sealing function from the pusher seal configuration and implements it through a different mechanism. The flexible membrane provides the necessary sealing without the axial movement that causes fretting and shredding in traditional pusher seal assemblies.

Inventive Principle:

Principle #2Taking out (Extraction)

3Reliability

If mechanical seal faces are used to provide sealing between rotating shaft and stationary housing, then sealing is provided, but frictional wear between seal faces causes gap formation leading to excessive leakage

Engineering Contradiction:

Improvesealing functionVSAvoidfrictional wear and leakage

Core Design Contradiction:

ReliabilityVSObject-generated harmful factors

Solution Approach 1:

The flexible membrane acts as an intermediary element that compensates for wear between the seal faces. By providing axial deflection capability, the membrane maintains the sealing function even as the rigid seal faces wear, preventing gap formation and excessive leakage.

Inventive Principle:

Principle #24Intermediary (Mediator)

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 flexible sealing membrane effectively maintains a seal at higher internal pressures by accommodating axial movement and wear, reducing frictional wear and seal failure, thereby enhancing the reliability and durability of rotary shaft equipment.

Implementation Method 1

a flexible sealing membrane (100) that, in operation, deflects axially to accommodate movement of the primary ring (36)

Methodology Applied

Scientific EffectElasticity: Elasticity

Implementation Method 2

biasing mechanism (500) that applies a closing force to engage the seal faces together

Methodology Applied

Scientific EffectSpring force: Spring

Data Source

PatentUS11808359B2Flexible sealing membrane and seal assembly for rotary shaft equipment

Publication Date: 2023.11.07 JOHN CRANE INC

AI summary

A mechanical seal assembly adapted for arrangement around a rotating shaft of a rotating device and has first and a second seal rings. The assembly also includes an annular carrier having a base and a removable end portion configured to be affixed to a housing of the rotating device. The assembly also includes an annular flexible sealing membrane. The membrane includes an outer portion arrangeable between the first seal ring and a biasing mechanism and that is axially shiftable relative to the rotating shaft. The membrane also includes an inner portion surrounded by the outer portion and positioned between the base and the removable end portion of the annular carrier and the base and a removable end portions hold the inner portion in fixed relative to the annular carrier as the outer portion shifts relative to the rotating shaft.