Vacuum Pump Rotor Balancing Through External Three-Plane Access
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Solution Overview
Problem
Existing turbo-molecular pumps face challenges in balance correction, particularly for rotary bodies, as they become eccentric during assembly and disassembly, leading to unbalance and bending vibrations, especially when handling speeds beyond the third critical speed.
Innovation Solution
The design incorporates multiple balance correction portions accessible from outside the case, including upper, intermediate, and lower balance correction portions with screw holes, allowing for n-plane (n≥3) balance correction, enabling access and adjustment without disassembling the rotary body, thus reducing unbalance and bending vibrations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If balance correction is performed on the rotary body before incorporation into the case, then balance correction can be performed with the rotary body attached to a balance correction tool, but the rotary body becomes eccentric with respect to a bearing due to the process of disassembling/assembling the rotary body upon incorporation into the case and unbalance occurs
Solution Approach 1:
The patent performs balance correction after the rotary body is incorporated into the case, but prepares balance correction portions and access ports in advance during manufacturing. This allows the balance correction to be performed at the optimal time (after assembly) without requiring disassembly, thus maintaining both precision and reliability
Solution Approach 2:
The patent introduces balance correction portions with access ports as intermediary structures that enable balance correction operations after assembly. These portions serve as mediators between the rotary body and external balance correction tools, allowing correction without disassembly and preventing eccentricity issues
2Ease of operation
If multiple screw holes are provided at the outer periphery of a disk for balance correction, then balance correction can be performed by screwing in balance correction screws, but balance correction for n (n≥3) planes cannot be performed
Solution Approach 1:
The patent divides the balance correction function into multiple segments by providing multiple balance correction portions at different locations (upper, intermediate, lower) on the rotary body. Each portion can be accessed independently through access ports, enabling segmented balance correction operations for n-planes while maintaining ease of operation
Solution Approach 2:
The patent extends balance correction from a single plane to multiple planes by adding the axial dimension. Balance correction portions are distributed along the axial direction of the rotary body, enabling n-plane balance correction by operating in both radial and axial dimensions simultaneously
Data Source
AI summary
A vacuum pump comprises: a rotary body including a rotor blade and a rotor shaft; a case rotatably housing the rotary body; a motor configured to drive the rotor shaft of the rotary body; a bearing arranged at an end portion of the rotor shaft; and at least three balance correction portions including a first balance correction portion provided on one end side of the rotary body in an axial direction, a second balance correction portion provided on the other end side of the rotary body in the axial direction, and a third balance correction portion provided between the first balance correction portion and the second balance correction portion. Balance correction by an n-plane method, where n≥3, is available such that any of the three balance correction portions is accessible from an outside of the case.