Vacuum Pump Stator Rotor Gap Design
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Solution Overview
Problem
Existing vacuum pumps with turbo-molecular pump parts face challenges in accurately setting gaps between stator and rotor blade wheels due to deformation and machining errors, leading to potential interference and reduced pump performance, and require expensive wire electric discharge machining for precise cutting.
Innovation Solution
The design includes a cylindrical pump case with alternately arranged rotor and stator blade wheels, using ring spacers to maintain gaps, and a stator blade wheel with a thicker outer ring part for finish machining, allowing for wider cutting or grinding without interference, reducing assembly errors and maintaining pump performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If wire electric discharge machining is used for precise cutting of stator blade wheels, then manufacturing precision is improved, but productivity is reduced and cost increases
Solution Approach 1:
The patent applies preliminary action by pre-setting the spacer thickness to include a positive clearance (0.05-0.5mm) that anticipates and compensates for potential interference between rotor and stator blades during operation. This pre-established clearance eliminates the need for ultra-precise wire electric discharge machining, allowing the use of more efficient conventional cutting methods while maintaining safe operational gaps.
Solution Approach 2:
The patent changes the critical parameter from 'minimal gap distance' to 'controlled clearance distance'. By deliberately designing the spacer thickness to create a positive clearance range (0.05-0.5mm) rather than attempting to achieve minimal theoretical gaps, the system transforms the manufacturing challenge into a controllable design parameter that can be achieved through conventional machining with higher productivity.
2Productivity
If conventional cutting methods are used for stator blade wheels, then productivity is improved, but manufacturing precision deteriorates due to wider cutting width causing interference
Solution Approach 1:
The patent introduces the spacer as an intermediary element that mediates between the rotor and stator blade wheels. The spacer's thickness is specifically designed to include a positive clearance (0.05-0.5mm) that compensates for the wider cutting width of conventional methods, preventing interference while allowing the use of productive conventional cutting techniques instead of precision wire electric discharge machining.
3Ease of operation
If spacers are used to maintain gaps between blade wheels, then assembly ease is improved, but manufacturing precision deteriorates due to accumulation of machining errors
Solution Approach 1:
The patent applies preliminary action by pre-calculating and incorporating a positive clearance (0.05-0.5mm) into the spacer thickness design. This pre-established tolerance buffer anticipates the accumulation of machining errors from multiple components (rotor blade, stator blade, spacer) and provides a safety margin that maintains consistent functional gaps even when individual component dimensions vary within their tolerance ranges.
Data Source
Figure 1
Figure 2(a)~2(b)
Figure 3(a)~3(b)
AI summary
[Problem to be Solved] Stator blade wheels and rotor blade wheels do not interfere with each other using lower-cost but wider cutting-width cutting or grinding for half-cutting-off of the stator blade wheels and not using expensive but narrower cutting-width wire electric discharge machining. [Solution] The distance h between a base end face 12ta (12tb) of a stator-blade-wheel outer ring part 12a and the corresponding rotor-blade end face 4aa (4ab), is set at a value larger than the maximum deformation of the running rotor blade wheel 4a during the pump operation. The larger distance h keeps perfectly stator-rotor separation, while the outer ring part 12a of a stator blade wheel 12 goes, in assembling, into the rotor area on account of large shift of any half of stator blade wheels owing to the wide cutting width. It makes also easy stator blade wheel assembling of the pump, as it is allowable to arrange half stator blade wheels with some eccentricity.