Scrolled Drive Ring for Mechanical Seal Cooling and Leakage Control

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Solution Overview

Problem

Mechanical seals in rotary shaft equipment experience frictional wear leading to gaps and leakage, requiring regular adjustments, and secondary seals suffer from axial movement causing fretting or shredding, while cooling efficiency is often inadequate due to insufficient fluid circulation.

Innovation Solution

A drive ring with scrolled features on its outer diameter is used to enhance fluid circulation and cooling, featuring parallelogram shapes and troughs, which can be formed via additive manufacturing, to maintain the rotating ring's fixed relationship with the shaft and improve heat transfer.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a mechanical seal assembly uses a dynamic secondary seal to provide a seal between the shaft and seal members, then sealing effectiveness is improved, but axial movement of the seal member causes fretting or shredding of the secondary seal

Engineering Contradiction:

Improvesealing effectivenessVSAvoidservice life of secondary seal

Core Design Contradiction:

ReliabilityVSDuration of action of moving object

Solution Approach 1:

A drive ring is introduced as an intermediary component between the rotating shaft and the rotating seal ring. The drive ring includes scrolled features that interact with the flush liquid to generate rotational force, while the rotating seal ring remains in fixed relationship with the shaft through the drive ring's structural connection. This mediator allows the seal ring to rotate with the shaft without direct axial movement relative to the shaft, preventing fretting of the secondary seal.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent replaces the traditional mechanical connection system (where the seal ring directly connects to the shaft) with a fluid-driven system. The drive ring uses scrolled features that are activated by flush liquid flow to rotate the seal ring, eliminating the need for direct mechanical coupling that causes axial movement and fretting.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

2Temperature

If flush liquid is provided to cool and lubricate the seal faces, then seal face temperature is reduced, but circulation efficiency is insufficient leading to inadequate cooling

Engineering Contradiction:

Improveseal face temperatureVSAvoidcooling efficiency

Core Design Contradiction:

TemperatureVSProductivity

Solution Approach 1:

The drive ring transforms the static or low-velocity flush liquid flow into a dynamic system that actively rotates the seal ring. The scrolled features on the drive ring convert fluid pressure into rotational motion, creating a dynamic cooling mechanism where the rotating seal ring enhances heat dissipation through increased fluid circulation and contact between the flush liquid and seal faces.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The patent utilizes hydraulic principles by employing the pressure and flow of flush liquid to drive the rotational motion of the seal ring through the scrolled features on the drive ring. This hydraulic activation improves cooling efficiency by ensuring adequate circulation of the flush liquid through the seal chamber and across the seal faces, rather than relying on passive or insufficient natural circulation.

Inventive Principle:

Principle #29Pneumatics and hydraulics

3Stability of the object's composition

If the rotating seal ring is directly connected to the shaft, then rotational alignment is maintained, but the seal ring cannot be cooled effectively due to insufficient fluid circulation

Engineering Contradiction:

Improverotational alignmentVSAvoidseal ring temperature

Core Design Contradiction:

Stability of the object's compositionVSTemperature

Solution Approach 1:

The patent segments the connection system into three distinct components: the stationary shaft, the rotating drive ring with scrolled features, and the rotating seal ring held in fixed relationship by the drive ring. This segmentation allows each component to perform its specific function - the shaft provides structural support, the drive ring converts fluid pressure to rotation, and the seal ring maintains sealing contact while being cooled by enhanced flush liquid circulation.

Inventive Principle:

Principle #1Segmentation

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 drive ring design increases fluid dwell time in the cooling chamber, enhancing cooling efficiency and minimizing vapor pocket formation, thereby improving seal performance and reducing maintenance needs.

Implementation Method 1

The drive ring design increases fluid dwell time in the cooling chamber, enhancing cooling efficiency

Methodology Applied

Scientific EffectFluid circulation: Convection

Implementation Method 2

enhancing cooling efficiency and minimizing vapor pocket formation, thereby improving seal performance

Methodology Applied

Scientific EffectHeat transfer: Convection

Data Source

PatentUS20250223972A1Drive ring for rotary shaft equipment seals

Publication Date: 2025.07.10 JOHN CRANE INC

AI summary

A mechanical seal assembly configured to be coupled to a rotating shaft of a machine, includes: rotating and stationary rings configured so that rotating ring rotates with the shaft and relative to the stationary ring; and a rotating ring drive ring that includes features formed at least on an outer surface thereof, the rotating drive ring configured to hold the rotating ring in a fixed relationship relative the rotating shaft. The features can increase the rotation of fluid near the seal when in operation.