Magnetic Bearing Rotor Sensor Target With Slit Non-Magnetic Ring
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Solution Overview
Problem
Existing rotor sensor targets for magnetic bearings are costly and prone to damage at high temperatures due to the use of expensive materials like Inconel, and cheaper alternatives compromise the magnetic portion's integrity.
Innovation Solution
A rotor sensor target design featuring a ring-shaped assembly of magnetic material mounted on a non-magnetic material with a ring-shaped slit, allowing for flexibility and the use of less expensive materials like aluminum, which maintains operational integrity across a wide temperature range without overstressing the magnetic components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If expensive materials like Inconel are used for the non-magnetic ring assembly, then the sensor target can withstand high temperatures and high speeds, but the production cost increases significantly
Solution Approach 1:
The patent changes the material parameters by substituting Inconel with cheaper materials like aluminum or stainless steel, and compensates for their lower temperature resistance through structural modifications (slits and spacing) that allow thermal expansion without damaging the magnetic laminations.
Solution Approach 2:
The patent introduces slits in the non-magnetic ring assembly that act as flexible elements, allowing the structure to expand and contract with temperature changes without transmitting excessive stress to the magnetic lamination stack, thereby enabling the use of cheaper materials.
2Speed
If the non-magnetic ring assembly is made very stiff to withstand high speeds, then the structural integrity is improved, but the magnetic portion becomes overstressed and prone to damage
Solution Approach 1:
The slits introduced in the non-magnetic ring assembly create a flexible structure that can accommodate centrifugal forces at high speeds without transmitting excessive stress to the magnetic laminations, thus protecting the magnetic portion while maintaining speed tolerance.
Solution Approach 2:
The non-magnetic ring assembly is segmented by introducing slits, which divides the continuous rigid structure into sections that can move independently, reducing stress transmission to the magnetic portion while maintaining overall structural integrity at high speeds.
3Ease of manufacture
If cheaper materials like aluminum are used for the non-magnetic ring assembly, then the production cost is reduced, but the structural strength and temperature resistance deteriorate
Solution Approach 1:
The patent modifies the structural parameters of the non-magnetic ring assembly by adding slits and optimizing the spacing between components, which compensates for the lower material strength of cheaper alternatives like aluminum, enabling reliable operation at high temperatures without using expensive Inconel.
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 enables the use of cost-effective materials while ensuring the magnetic components remain within their yield tensile strength, allowing operation at high temperatures without damaging the sensor target, thus reducing production costs and improving manufacturing ease.
Implementation Method 1
the coefficient of thermal expansion very close to the steel coefficient of thermal expansion... allows the sensor to be used in a wide range of temperatures
Implementation Method 2
When the position sensors are of the inductive type, the rings of rotor laminations such as the stacks of ferromagnetic laminations 233, 253 and 253' in FIG. 9 and their support are called a rotor sensor target
Data Source
AI summary
A rotor sensor target for magnetic bearings, the rotor sensor target comprising a ring-shaped assembly of magnetic material mounted on a generally ring-shaped assembly of non-magnetic material. The magnetic and non-magnetic ring shaped assemblies are coaxially arranged and mounted on a shaft having a longitudinal axis of rotation X′-X. The generally ring-shaped assembly of non-magnetic material comprises at least one ring-shaped slit having the longitudinal axis X′-X and may be made of a cheaper material, such as aluminum. The ring-shaped slit provides flexibility which permits operation over a wide range of temperatures without risking of damaging the ring-shaped assembly of magnetic material.