Rotary Apparatus Rotor Spacer for End Ring Stability
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Solution Overview
Problem
Conventional turbomolecular pumps face issues with radial deformation and stress-induced natural frequency changes due to high-speed rotation, particularly caused by the thermal expansion of aluminum motor end rings, which can lead to rotor instability and breakage.
Innovation Solution
A rotary apparatus design that includes a rotor spacer covering the motor end ring, with axial and radial gaps to prevent thermal stress and deformation, using materials like silicon steel and stainless steel alloys for the rotor core and spacer to manage thermal expansion and centrifugal forces, and a tapered cross-sectional shape for the motor end ring to reduce deformation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the motor end ring is made of cast pure aluminum to connect conductors, then ease of manufacture is improved, but radial deformation and thermal expansion cause rotor instability at high speeds
Solution Approach 1:
The invention replaces the single-material cast pure aluminum end ring with a composite structure consisting of an aluminum end ring and a reinforcing ring made of different material (steel or stainless steel). This composite structure combines the ease of manufacturing aluminum with the high strength and low thermal expansion of steel, resolving the contradiction between manufacturability and rotor stability at high speeds.
Solution Approach 2:
The end ring is segmented into two distinct components: the aluminum end ring for electrical connection and the reinforcing ring for structural support. This segmentation allows each component to be optimized for its specific function while being manufactured separately and assembled together, maintaining ease of manufacture while eliminating radial deformation issues.
2Device complexity
If the motor end ring is cantilevered to reduce assembly complexity, then device complexity is reduced, but centrifugal force causes elastic deformation and stress at high rotation speeds
Solution Approach 1:
The cantilevered end ring structure is replaced by a segmented design where the aluminum end ring is combined with a separate reinforcing ring. This segmentation provides structural support without increasing assembly complexity, as the reinforcing ring is designed to be integrated with the existing end ring geometry.
Solution Approach 2:
The composite structure of aluminum end ring plus reinforcing ring provides the necessary strength to resist centrifugal force at high rotation speeds, while maintaining a relatively simple overall structure. The reinforcing ring is positioned to provide maximum structural support with minimal additional complexity.
3Shape
If the motor end ring contacts the rotor spacer axially to reduce deformation, then radial deformation is reduced, but thermal expansion creates internal stress and changes natural frequency
Solution Approach 1:
The aluminum end ring in the composite structure has lower thermal expansion characteristics than pure aluminum due to the reinforcing ring. The reinforcing ring constrains thermal expansion, reducing internal stress during operation while maintaining shape stability. This resolves the contradiction between shape stability and internal stress generation.
Solution Approach 2:
The thermal expansion parameter is effectively changed by combining aluminum with a low-expansion material (steel or stainless steel). The composite structure exhibits reduced thermal expansion compared to pure aluminum, allowing axial contact with the rotor spacer without generating excessive internal stress or changing natural frequency.
4Productivity
If the rotor rotates at high speed to improve productivity, then output increases, but centrifugal force causes deformation and potential breakage
Solution Approach 1:
The composite structure of aluminum end ring plus reinforcing ring enables the rotor to withstand high rotation speeds by providing the necessary strength to resist centrifugal force. The reinforcing ring prevents radial deformation and potential breakage, allowing high-speed operation for improved productivity while maintaining rotor reliability.
Solution Approach 2:
The segmented structure with the reinforcing ring provides localized strength enhancement at critical areas of the rotor, enabling high-speed rotation without compromising reliability. The segmentation allows the rotor to achieve high productivity through increased rotation speed while the reinforcing structure prevents deformation and breakage.
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
The design ensures stable high-speed rotation by preventing radial deformation and thermal stress-induced natural frequency changes, enhancing the reliability and longevity of the rotor.
Implementation Method 1
the motor end ring 13b, when rotated at a high speed, elastically deforms by centrifugal force, etc.
Implementation Method 2
Because the motor end ring 13b, made of aluminum, has a larger expansion coefficient than other members made of other materials, an axial internal stress acts on the motor end ring 13b and the rotor spacer 20 when the motor end ring 13b generates heat.
Implementation Method 3
a rotor shaft, to which a rotor of an induction motor is fixed, rotates at a relatively high speed by the torque of the induction motor
Data Source
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AI summary
A rotary apparatus, in which a rotor (10) can rotate stably when it rotates at a high speed, can rotate at a relatively high speed by the torque of a highly reliable induction motor. The rotary apparatus comprises a rotor shaft (11) and an induction motor. The induction motor includes a motor rotor core (13a) fixed to the rotor shaft (11), conductors disposed in the motor rotor core (13a) and a motor end ring (13b) for assembling and connecting the conductors, and can rotate the rotor shaft (11) at a high speed by the torque. The rotor shaft (11) is provided with a member that covers the motor end ring.