Wave Spring Mechanical Seal for Uniform Axial Contact Pressure

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Solution Overview

Problem

Existing mechanical seals face issues with wear and fatigue of springs and contact surfaces, as well as uneven pressure distribution due to axial displacements, leading to friction, overheating, and fluid seepage.

Innovation Solution

A mechanical seal design incorporating a wave spring with specific shape couplings and recesses between the annular body and sealing element, which maintains uniform contact pressure and reduces sliding and rotary drag, using a wave spring with adjustable elastic constant to absorb axial movements and maintain fluid-tight sealing.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If conventional springs are used in mechanical seals, then the seal can maintain contact pressure between sealing surfaces, but the springs suffer from wear and fatigue leading to reduced reliability

Engineering Contradiction:
Improvefatigue resistanceVSAvoidspring service life
Core Design Contradiction:
ReliabilityVSDuration of action of moving object

Solution Approach 1:

The patent changes the physical parameters of the elastic element by using a wave spring with specific geometric characteristics (wave depth, wavelength, cross-section shape) instead of conventional spiral or conical springs. This parameter change provides superior fatigue resistance and elastic performance, directly resolving the contradiction between maintaining contact pressure and improving reliability.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The wave spring features non-uniform local geometry with varying wave depths and cross-sectional dimensions along its length. This local quality variation optimizes the elastic response and stress distribution, allowing the spring to better absorb axial movements while resisting fatigue, thus improving both reliability and service life.

Inventive Principle:
Principle #3Local quality

2Adaptability or versatility

If axial displacement of the crankshaft occurs, then the engine can accommodate thermal expansion and manufacturing tolerances, but the pressure between sealing surfaces becomes uneven causing friction and overheating

Engineering Contradiction:
Improveaxial displacement toleranceVSAvoidsealing surface temperature
Core Design Contradiction:
Adaptability or versatilityVSTemperature

Solution Approach 1:

The wave spring provides dynamic elastic response to axial displacements, automatically adjusting its compression to maintain optimal contact pressure. This dynamic adaptation ensures that during thermal expansion or tolerance variations, the sealing surfaces remain in proper contact without excessive friction or overheating, resolving the contradiction between adaptability and temperature control.

Inventive Principle:
Principle #15Dynamics

3Adaptability or versatility

If axial displacement occurs, then the engine can accommodate dimensional variations, but the spring compression changes significantly altering sealing pressure

Engineering Contradiction:
Improveaxial movement accommodationVSAvoidsealing surface pressure uniformity
Core Design Contradiction:
Adaptability or versatilityVSStress or pressure

Solution Approach 1:

The wave spring's geometric parameters (wave depth, wavelength, thickness) are specifically designed to provide a controlled elastic response. This allows the spring to accommodate axial movements while maintaining relatively uniform pressure distribution on the sealing surfaces, resolving the contradiction between adaptability and pressure uniformity.

Inventive Principle:
Principle #35Parameter changes

4Force

If elastic bands are used to absorb axial movements, then the seal can maintain contact pressure, but the elastic bands come into contact with liquid requiring sealing

Engineering Contradiction:
Improvecontact pressure maintenanceVSAvoidsealing structure complexity
Core Design Contradiction:
ForceVSDevice complexity

Solution Approach 1:

The wave spring is integrated directly into the mechanical seal assembly, combining the elastic element and sealing function into a unified structure. This merging eliminates the need for separate sealing arrangements for the elastic element, reducing device complexity while maintaining contact pressure through the wave spring's inherent elastic properties.

Inventive Principle:
Principle #5Merging (Combining)

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 mechanical seal achieves improved fatigue resistance, maintains uniform contact pressure, and prevents fluid seepage by reducing wear and friction, while allowing for controlled axial movements and fluid-tight operation.

Implementation Method 1

a wave spring with adjustable elastic constant to absorb axial movements and maintain fluid-tight sealing

Methodology Applied
Scientific EffectElasticity: Elasticity

Implementation Method 2

maintains uniform contact pressure

Methodology Applied
Scientific EffectPressure distribution: Pressure Increase

Data Source

PatentEP3643950B1Mechanical seal
Publication Date: 2022.06.29 FLUITEN ITAL
  • EP3643950B1 patent drawingFigure 1~2
  • EP3643950B1 patent drawingFigure 3~4
  • EP3643950B1 patent drawingFigure 5~6

AI summary

A mechanical seal comprises a rotating part (100) connectable to a rotating shaft (A) and a fixed part (200) connectable to a fixed wall (P); the rotating part (100) comprises an annular body (110) rigidly connectable to a shaft (A) rotating about a rotation axis (R); a sealing element (130) that has a rotating coupling surface (101) configured for abutting against a respective static coupling surface (201) of the fixed part (200); and elastic means active between the annular body (110) and the sealing element (130) for maintaining the rotating coupling surface (101) pressed against the static coupling surface (201) and allowing a mutual position adjustment along the rotation axis (R) between the annular body (110) and the sealing element (130). The elastic means comprise a wave spring (150) having a substantially annular profile, that has a first shape coupling with the annular body (110) configured for rotationally constraining the wave spring (150) to the annular body (110) around the rotation axis (R) and a second shape coupling with the sealing element (130) configured for rotationally constraining the sealing element (130) to the wave spring (150) around the rotation axis (R).