Magnetic Pump Bush Retention With Offset Recess Push-Fit

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Solution Overview

Problem

The existing bushing system in magnetic drive pumps requires multiple metallurgies and interference fits to accommodate varying application temperatures and process liquid compatibility, making it complex and difficult to assemble and maintain, especially in field conditions.

Innovation Solution

A bushing system with a bush holder and bush featuring axially offset retention member recesses and a compliant retention member that provides a biasing force to securely hold the bush in place without interference fitting, using a retention member such as an o-ring to ensure proper alignment and prevent rotation, allowing for a simple push-fit assembly.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If interference fits are used to retain bushes in the bush holder, then the bushes are rigidly fixed and prevented from rotating, but the system requires specialist equipment and is extremely difficult to facilitate in the field

Engineering Contradiction:
Improvebush retentionVSAvoidassembly difficulty
Core Design Contradiction:
ReliabilityVSEase of operation

Solution Approach 1:

The retention mechanism is segmented into separate components: a retention groove in the bush holder and a corresponding retention protrusion on the bush. This allows the bush to be retained without requiring interference fitting, enabling simple snap-fit assembly while maintaining secure retention.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

A retention protrusion acts as an intermediary feature between the bush and bush holder, providing a mechanical interlock that replaces the need for interference fits. This intermediary feature enables reliable retention through simple geometric engagement rather than forceful interference assembly.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Adaptability or versatility

If multiple metallurgies and interference fits are employed to cater for process liquid compatibility and temperature ranges, then material compatibility is achieved, but the device complexity increases

Engineering Contradiction:
Improvematerial compatibilityVSAvoidsystem complexity
Core Design Contradiction:
Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The system is segmented into separable bush and bush holder components with standardized retention features. This segmentation allows different bush materials to be used for different chemical compatibility requirements while maintaining a universal bush holder design, reducing overall system complexity.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The bush holder with its standardized retention groove serves as a universal component that can accommodate different bush materials and designs. The retention mechanism itself is universal, working with various bush types regardless of material composition, thereby simplifying the overall system.

Inventive Principle:
Principle #6Universality (Multi-functionality)

3Strength

If interference fits are used to retain bushes, then the bushes stay compressed to prevent cracking, but specialist equipment is required for assembly

Engineering Contradiction:
Improvebush compressionVSAvoidassembly equipment
Core Design Contradiction:
StrengthVSEase of manufacture

Solution Approach 1:

The compression and retention functions are segmented into separate mechanisms: the retention groove and protrusion provide mechanical retention, while a biasing element provides the compressive force. This eliminates the need for interference fitting to achieve compression, allowing simple manual or tool-free assembly.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

A biasing element acts as an intermediary that provides the necessary compressive force on the bush without requiring interference fitting. This mediator component delivers the compression force through elastic or spring mechanisms, enabling assembly without specialized equipment while maintaining the required compressive strength.

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

This solution simplifies the assembly and maintenance of magnetic drive pumps by eliminating the need for interference fits and specialist equipment, reducing the number of required bush holder sizes, and enabling field servicing, while enhancing operational reliability and extending the lifespan of the components.

Implementation Method 1

The retention member and the axially offset recesses may combine to provide a biasing force which urges the bush and bush holder towards each other

Methodology Applied
Scientific EffectElasticity: Elasticity

Data Source

PatentEP4038281B1Bush retention system
Publication Date: 2024.12.04 HMD SEALLESS PUMPS
  • EP4038281B1 patent drawingFigure 1
  • EP4038281B1 patent drawingFigure 2
  • EP4038281B1 patent drawingFigure 3

AI summary

A bushing system for use in a magnetic drive or canned motor pump, the system comprising: a bush holder having an axial recess for receiving a bush, a bush for insertion into the axial recess, the bush and bush holder each having: one or more cooperating features which abut against each other when the bush is fitted into the recess; and a recess for receiving at least part of a retention member; wherein, when the cooperating features abut, the retention member recesses on the bush holder and the bush are axially offset.