Linear Synchronous Motor Tooth Protrusion for Thrust Uniformity
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Solution Overview
Problem
In linear synchronous motors, the variation in magnetic flux density across teeth leads to uneven thrust forces and cogging torque, causing periodic variations in thrust force generation due to the differing magnetic flux densities at the ends of the core member, which conventional solutions attempt to address by altering tooth arrangement or thickness but result in reduced slot space and thrust force.
Innovation Solution
The design includes a core member with teeth where the distal ends of the teeth corresponding to alternating current phases are adjusted to protrude differently, ensuring equalized magnetic flux densities across groups of teeth, thereby minimizing thrust force and cogging torque variations by optimizing the spacing and length of teeth.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the teeth at both ends of the core member are made to have the same length as the intermediate teeth, then the structure is simple and easy to manufacture, but the magnetic flux density becomes uneven causing thrust force variation and cogging torque
Solution Approach 1:
The patent applies local quality by making the teeth at both ends of the core member have different lengths from the intermediate teeth. Specifically, the distal ends of the teeth corresponding to alternating current phases are made to protrude differently, creating local structural variations that equalize magnetic flux densities across different tooth groups. This resolves the contradiction by sacrificing overall structural simplicity for local optimization of magnetic field distribution, thereby ensuring uniform thrust force generation.
2Reliability
If conventional solutions alter tooth arrangement or thickness to address magnetic flux density variation, then thrust force uniformity improves, but slot space reduces and thrust force generation capability decreases
Solution Approach 1:
The patent resolves this contradiction by introducing a new dimensional approach - varying the protrusion distance of tooth distal ends in the axial direction (length dimension) rather than altering tooth arrangement in the radial direction or changing tooth thickness. This dimensional change allows equalization of magnetic flux densities while preserving slot space and maintaining thrust force generation capability, as the coil winding space is not compromised.
3Device complexity
If the distal ends of all teeth are made to protrude equally, then the manufacturing process is simplified, but periodic variations in thrust force occur due to uneven magnetic flux density at the ends of the core member
Solution Approach 1:
The patent applies asymmetry by deliberately creating asymmetric tooth length configurations at the ends of the core member. The teeth corresponding to different alternating current phases have different protrusion distances, with at least one tooth distal end protruding further than the others. This asymmetric design breaks the periodic variation pattern in magnetic flux density, thereby eliminating thrust force ripple while maintaining manageable device complexity through a systematic tooth length differentiation approach.
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 ensures a more uniform thrust force generation and reduced cogging torque variations, maintaining the thrust force while simplifying assembly and reducing the complexity of the linear motor actuator.
Implementation Method 1
a stator magnet having N poles and S poles alternately linearly arranged to generate a magnetic field
Implementation Method 2
a mover for generating a shifting magnetic field along an arrangement direction of the magnetic poles of the stator magnet by virtue of passage of the alternating current
Implementation Method 3
Between the shifting magnetic field generated by the mover and the magnetic field generated by the stator magnet, a magnetic attractive force or a magnetic repulsive force is generated
Implementation Method 4
a core member made of a ferromagnetic material such as iron... To the core member, teeth... are provided
Data Source
AI summary
Provided is a linear synchronous motor in which, when a three-phase alternating current passes through a coil of a mover, thrust forces generated by the alternating currents of each phase are equalized, thereby making it possible to minimize variation in thrust force, the linear synchronous motor including: a stator magnet (4) in which N poles and S poles are alternately arranged linearly; and a mover (5) which is opposed to the stator magnet (4) at an interval therefrom, and which generates a shifting magnetic field along with passage of a three-phase alternating current, for applying a thrust force to the stator magnet (4), in which: the mover (5) includes a core member (50) in which teeth (52), the number of which is a whole-number multiple of a number of phases of the alternating currents, are arranged, and a coil (51) which is wound around the teeth (52) and through which the alternating current of any one of the phases passes; and of the plurality of teeth (52) provided to the core member (50), the teeth (52) corresponding to a u phase and a w phase of the alternating currents passing through the coil (51) wound around the teeth (52) at both ends of the core member (50) have distal ends protruding toward the stator magnet (4) further than distal ends of the residual teeth (52).