Vacuum Pump Shaft Support with Axial Springs

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Solution Overview

Problem

Turbomolecular vacuum pumps face a challenge in balancing the contradictory requirements of axial stiffness and oscillation capability in their roller bearings, which are compromised by the use of elastomeric materials and affected by the axial deflection of permanent magnetic bearings, leading to increased strain on the fore-vacuum roller bearing.

Innovation Solution

A shaft support arrangement featuring a roller bearing mount with a vibrating platform and metallic connecting elements that allow axial and radial movements, utilizing axial springs to enhance axial rigidity while maintaining oscillation capability, thereby compensating for the limitations of elastomeric materials and reducing positional inaccuracies.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If the roller bearing is embedded in elastomeric materials to enable oscillation, then the oscillation capability is improved, but the resistance to axial forces deteriorates

Engineering Contradiction:
Improveoscillation capabilityVSAvoidresistance to axial forces
Core Design Contradiction:
Adaptability or versatilityVSStrength

Solution Approach 1:

The mount is divided into separate functional components: metallic connecting elements for structural support and oscillation, and axial springs for force resistance. This segmentation allows each component to specialize in its intended function without compromise.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The mount combines metallic materials (for structural integrity and oscillation) with spring elements (for axial force resistance), creating a composite structure that achieves both oscillation capability and axial force resistance simultaneously.

Inventive Principle:
Principle #40Composite materials

2Adaptability or versatility

If elastomeric materials are used for the bearing mount, then oscillation is enabled, but manufacturing precision and reproducibility deteriorate due to large tolerances

Engineering Contradiction:
Improveoscillation capabilityVSAvoidpositional accuracy
Core Design Contradiction:
Adaptability or versatilityVSManufacturing precision

Solution Approach 1:

The patent replaces elastomeric materials with a metallic mounting structure featuring precision-machined surfaces and fixed positioning elements. This substitution eliminates material-dependent tolerance variations and enables consistent positional accuracy through precision manufacturing.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

3Adaptability or versatility

If the permanent magnetic bearing is deflected from normal position, then axial loading occurs, but additional axial forces are generated that strain the roller bearing

Engineering Contradiction:
Improveaxial loading capabilityVSAvoidaxial forces on roller bearing
Core Design Contradiction:
Adaptability or versatilityVSForce

Solution Approach 1:

Axial springs are introduced as intermediary elements between the roller bearing and housing. These springs absorb and cushion axial forces generated during rotor deflection, preventing direct transmission of high axial loads to the roller bearing while still permitting controlled axial movement.

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 allows for effective handling of high axial forces while maintaining axial and radial oscillation, improving reproducibility and reducing the dependency on material properties, with no degradation over time or temperature variations, and minimal space usage.

Implementation Method 1

axial springs which provide support in the axial direction

Methodology Applied
Scientific EffectElasticity: Elasticity

Implementation Method 2

the storage is based on a repelling effect. Since the polarity is the same in each layer of the stack, the storage is based on a repelling effect.

Methodology Applied
Scientific EffectMagnetic repulsion: Ion Repulsion/Attraction

Data Source

PatentEP1890041B1Assembly for supporting the shaft of a vacuum pump
Publication Date: 2009.11.18 PFEIFFER VACUUM GMBH
  • EP1890041B1 patent drawingFigure 1
  • EP1890041B1 patent drawingFigure 2
  • EP1890041B1 patent drawingFigure 3~4

AI summary

The arrangement has a housing with a bearing (8) and another bearing (9) is arranged in a mounting plate (10) with axial and radial rigidity. A tilting platform is connected with the adjustment held in the housing by metallic connecting components enabling axial and radial movements of the tilting platform. The rigidity of the mounting plate in axial direction is larger than the rigidity of the mounting plate in radial direction by the axial springs arranged between tilting platform and adjustment. The axial rigidity of the mounting plate is larger than the former bearing.