Turbomolecular Pump Stator Disk Overlap Prevention

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Solution Overview

Problem

Turbomolecular pumps face issues with the overlapping of indexing disks due to the thin metal sheets used in stator-side blade rings, leading to incorrect blade positioning and potential contact between rotor-side and stator-side components, especially under high gas loads, which can result in pump failure.

Innovation Solution

The design incorporates a stator disk with a first and second dividing disk featuring a tilted impact surface and a bead on the second dividing disk's supporting ring section, preventing overlap by increasing the effective axial thickness and ensuring precise positioning through abutting surfaces and tabs, allowing for identical disk production and enhanced mechanical robustness.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If thin sheet metal is used to manufacture stator disks by punching or cutting blades, then manufacturing cost is reduced and ease of manufacture is improved, but the thin lamination causes sub-discs to slip over one another during assembly, leading to incorrect blade positioning and potential contact between rotor-side and stator-side components

Engineering Contradiction:
Improveease of manufactureVSAvoidblade positioning precision
Core Design Contradiction:
Ease of manufactureVSManufacturing precision

Solution Approach 1:

The invention introduces a protrusion on the first sub-disk and a corresponding recess on the second sub-disk, creating a mechanical interlocking feature in the axial dimension. This prevents the thin sheet metal sub-discs from slipping over one another during assembly, thereby maintaining correct blade positioning while preserving the cost-effective thin sheet metal construction approach.

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

2Ease of manufacture

If thin sheet metal is used for stator disks, then manufacturing cost is reduced, but the support ring sections overlap under high gas loads, causing pump failure

Engineering Contradiction:
Improvemanufacturing costVSAvoidpump reliability
Core Design Contradiction:
Ease of manufactureVSReliability

Solution Approach 1:

By adding the protrusion-recess feature in the axial dimension, the invention prevents overlapping of support ring sections under high gas loads. The mechanical interlock ensures that the thin sheet metal construction does not compromise pump reliability, allowing the stator disk to maintain its cost-effective thin design while withstanding operational stresses.

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

3Manufacturing precision

If the contact surface has sections above and below the plane of the disk, then overlap prevention is enhanced and positioning is improved, but device complexity increases

Engineering Contradiction:
Improvepositioning precisionVSAvoiddevice complexity
Core Design Contradiction:
Manufacturing precisionVSDevice complexity

Solution Approach 1:

The contact surface is segmented into two functional sections: one above the disk plane and one below the disk plane. This segmentation provides overlapping prevention in both axial directions while maintaining a relatively simple overall structure. The protrusion-recess feature is divided into these two sections, each contributing to positioning precision without requiring a completely complex design.

Inventive Principle:
Principle #1Segmentation

Data Source

PatentEP2458221B1Turbomolecular pump
Publication Date: 2020.07.01 PFEIFFER VACUUM GMBH
  • EP2458221B1 patent drawingFigure 1
  • EP2458221B1 patent drawingFigure 2~3
  • EP2458221B1 patent drawingFigure 4~5

AI summary

The pump has a rotor, and a sheet rotor disk comprising a supporting ring and two partial disks, where the partial disks are provided with respective supporting ring sections (56, 58). The rotor has a shaft, and the rotor disk is arranged on the shaft. One of the ring sections has an abutting surface (64) that is tilted against a disk plane (54), where another ring section is pushed against the abutting surface. The abutting surface is arranged at a latch (62) that works together with a stator component for fixing one of the partial disks in a radial plane.