Cylindrical Linear Motor Halbach Array Thrust
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Solution Overview
Problem
Cylindrical linear motors face limitations in thrust improvement due to high magnetic resistance between permanent magnets and the armature, despite increased residual magnetic flux density, as the coercive force of sub magnetic pole magnets is higher than that of main magnetic pole magnets, making further thrust enhancement difficult.
Innovation Solution
A cylindrical linear motor design with a Halbach array configuration, where the axial length of the main magnetic pole permanent magnets is longer than that of the sub magnetic pole, and the sub magnetic pole magnets have a higher coercive force, reducing magnetic resistance and suppressing demagnetization, allowing for increased magnetic field and thrust.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If the axial length of permanent magnets is increased to reduce magnetic resistance and improve thrust, then the thrust is improved, but the coercive force requirement increases to prevent demagnetization
Solution Approach 1:
The patent applies different axial lengths to different types of permanent magnets within the Halbach array. Specifically, permanent magnets at odd positions (main magnetic poles) have a first axial length, while permanent magnets at even positions (sub magnetic poles) have a second axial length that is shorter than the first. This local differentiation allows the main magnetic poles to generate sufficient magnetic flux for high thrust while the sub magnetic poles maintain appropriate coercive force characteristics to prevent demagnetization under the influence of the main magnetic pole fields.
2Force
If the residual magnetic flux density of main magnetic pole permanent magnets is increased to improve thrust, then the magnetic field strength increases, but the risk of demagnetization in sub magnetic pole permanent magnets increases
Solution Approach 1:
The patent implements local quality differentiation by assigning different axial lengths to permanent magnets at odd positions versus even positions in the Halbach array. The permanent magnets at odd positions (main magnetic poles) are designed with a longer axial length to generate high residual magnetic flux density and strong magnetic fields for improved thrust. Meanwhile, permanent magnets at even positions (sub magnetic poles) are designed with a shorter axial length, which reduces their exposure to demagnetizing fields from the main magnetic poles, thereby preventing demagnetization while maintaining overall system performance.
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
This configuration effectively reduces magnetic resistance, allows for a higher magnetic field on the core, and enhances thrust while preventing demagnetization of the sub magnetic pole, achieving up to 98% of ideal thrust while maintaining high residual magnetic flux density.
Implementation Method 1
when the U-phase, V-phase, and W-phase windings of the armature are appropriately energized, the armature is attracted to the permanent magnet, and the armature is driven as a movable element axially with respect to the stator
Implementation Method 2
permanent magnets of a main magnetic pole radially magnetized and permanent magnets of a sub magnetic pole axially magnetized that are alternately arranged in a Halbach array
Data Source
AI summary
To achieve the above object, a cylindrical linear motor of the present invention includes a cylindrical linear motor includes: a core having a cylindrical yoke, and a plurality of teeth that are annular and are provided at intervals in an axial direction on an outer periphery of the yoke; a winding mounted in slots between the teeth; and a field which is cylindrical and in which the core is inwardly inserted movably in the axial direction to arrange N poles and S poles alternately in the axial direction, wherein the field has permanent magnets of a main magnetic pole radially magnetized and permanent magnets of a sub magnetic pole axially magnetized that are alternately arranged in a Halbach array in the axial direction, an axial length of the permanent magnet of the main magnetic pole is longer than an axial length of the permanent magnet of the sub magnetic pole, and the permanent magnet of the sub magnetic pole has a coercive force higher than that of the permanent magnet of the main magnetic pole.