Sliding Surface Groove Layout for Bidirectional Mechanical Seals

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Solution Overview

Problem

Mechanical seals with dynamic pressure generation grooves fail to separate sliding surfaces effectively during reverse rotation, leading to lubricity issues due to uneven pressure distribution.

Innovation Solution

The design includes first and second dynamic pressure generation grooves on sliding surfaces, with the first groove becoming shallower and the second groove deeper towards the downstream side during forward rotation, and vice versa during reverse rotation, ensuring consistent positive pressure generation in both directions to separate the sliding surfaces.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If dynamic pressure generation grooves are provided on the sliding surface for forward rotation, then lubricity is improved for forward rotation, but sliding surfaces cannot be separated for reverse rotation

Engineering Contradiction:

ImprovelubricityVSAvoidbidirectional operation capability

Core Design Contradiction:

ReliabilityVSAdaptability or versatility

Solution Approach 1:

The groove bottoms are configured with asymmetric inclination relative to the radial direction, creating different pressure generation characteristics for forward and reverse rotations. This asymmetry allows the first groove to generate positive pressure during forward rotation while the second groove generates positive pressure during reverse rotation, enabling bidirectional lubrication.

Inventive Principle:

Principle #4Asymmetry

Solution Approach 2:

The patent introduces a second dynamic pressure generation groove with opposite inclination direction to the first groove. When rotation direction is inverted, the second groove becomes the active pressure-generating groove, effectively reversing the pressure generation mechanism to accommodate reverse rotation and solve the unidirectional limitation.

Inventive Principle:

Principle #13The other way round (Inversion)

2Stress or pressure

If the first dynamic pressure generation groove is inclined to generate positive pressure during forward rotation, then sliding surfaces separate during forward rotation, but the same groove configuration generates negative pressure during reverse rotation

Engineering Contradiction:

Improvepositive pressure generationVSAvoidpressure distribution uniformity

Core Design Contradiction:

Stress or pressureVSReliability

Solution Approach 1:

Different regions of the sliding surface are equipped with grooves having different local qualities - the first groove has inclination suited for forward rotation pressure generation, while the second groove has opposite inclination suited for reverse rotation. This local differentiation ensures optimal pressure generation in each rotation direction without compromising the other.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The sliding surface is designed with dual groove configurations that provide multi-functionality - the first groove serves forward rotation while the second groove serves reverse rotation. Both grooves are always present but only one is actively generating positive pressure at any given rotation direction, achieving universal lubrication capability.

Inventive Principle:

Principle #6Universality (Multi-functionality)

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

This configuration ensures reliable separation of sliding surfaces and maintains excellent lubricity for both forward and reverse rotations by generating positive pressures in both grooves, reducing leakage and wear.

Implementation Method 1

positive pressures are easily increased on the downstream side of the relative rotation of the first dynamic pressure generation groove and the second dynamic pressure generation groove, and the sealed fluid is collected at the center of the sliding surface in the radial direction to form a fluid film

Methodology Applied

Scientific EffectDynamic pressure generation: Pressure Gradient

Implementation Method 2

in the second dynamic pressure generation groove, since a relative negative pressure is generated in the vicinity of an end portion on an upstream side of the relative rotation

Methodology Applied

Scientific EffectNegative pressure generation: Pressure Gradient

Implementation Method 3

the sealed fluid concentrates on the end portion to generate a positive pressure, so that the sliding surfaces are separated from each other, and a fluid film of the sealed fluid is formed between the sliding surfaces

Methodology Applied

Scientific EffectHydrodynamic lubrication: Lubrication

Data Source

PatentUS20240344555A1Sliding parts

Publication Date: 2024.10.17 EAGLE INDS

AI summary

In sliding parts which is disposed at a relative rotational location of a rotating machine, and in which a first dynamic pressure generation groove extending so as to be inclined with respect to a relative rotation direction and a second dynamic pressure generation groove extending so as to be inclined in a direction opposite to the inclination direction of the first dynamic pressure generation groove with respect to the relative rotation direction in a plan view are provided on a sliding surface, bottom surfaces of the first dynamic pressure generation groove and the second dynamic pressure generation groove are inclined in the same direction with respect to a radial direction in a cross-sectional view.