Linear Motor Gap Assembly via Magnetic Positioning

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Solution Overview

Problem

The assembly of linear motors is challenging due to strong magnetic attraction forces between the armature core and permanent magnet arrays, making it difficult to maintain an accurate gap between the stator and mover, which is essential for generating adequate propulsion force, and this complicates the assembly process in component mounting and inspecting apparatuses.

Innovation Solution

A linear motor design that includes a frame member with a stator and mover positioned using first and second positioning portions to establish a fixed gap without the need for shims, allowing the mover to reciprocate along a linear direction, enabling easy and precise assembly by utilizing magnetic attraction forces while preventing undue magnetic attachment.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If shims are used to adjust the gap between stator and mover, then the gap can be accurately controlled, but the assembly process becomes complex and time-consuming

Engineering Contradiction:
Improvegap accuracyVSAvoidassembly complexity
Core Design Contradiction:
Manufacturing precisionVSDevice complexity

Solution Approach 1:

The patent removes the shim component from the assembly process entirely. Instead of using shims to adjust and maintain the gap between stator and mover, the design incorporates positioning portions directly into the motor structure that automatically establish the correct gap through magnetic attraction forces, eliminating the need for separate gap-adjustment components.

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The linear motor structure uses its own magnetic attraction forces to automatically position and maintain the correct gap between stator and mover during assembly. The positioning portions are designed so that when the armature core and permanent magnet array are brought together, the magnetic forces themselves establish and maintain the precise gap without requiring external adjustment tools or components.

Inventive Principle:
Principle #25Self-service

2Force

If strong magnetic attraction forces are utilized for motor operation, then propulsion force is adequate, but assembly becomes difficult due to magnetic attachment

Engineering Contradiction:
Improvepropulsion forceVSAvoidassembly ease
Core Design Contradiction:
ForceVSEase of manufacture

Solution Approach 1:

The patent divides the assembly process into distinct phases with dedicated positioning portions. The first positioning portion allows initial approach and alignment, while the second positioning portion establishes the final operating gap. This segmentation enables controlled assembly despite strong magnetic forces by providing intermediate stopping points that guide the assembly process.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The positioning portions act as intermediaries between the strong magnetic attraction forces and the assembly process. These structured features provide controlled interaction points that mediate the magnetic forces, allowing the armature core and permanent magnet array to be assembled without being uncontrollably attracted to each other, while still maintaining adequate propulsion force during operation.

Inventive Principle:
Principle #24Intermediary (Mediator)

3Force

If the gap between stator and mover is reduced to increase propulsion force, then motor performance improves, but positioning accuracy becomes more difficult to maintain

Engineering Contradiction:
Improvepropulsion forceVSAvoidpositioning accuracy
Core Design Contradiction:
ForceVSManufacturing precision

Solution Approach 1:

The patent incorporates preliminary positioning features directly into the motor structure. The first and second positioning portions are pre-designed to establish the correct gap distance before the motor begins operation. This preliminary action ensures that the optimal gap for maximum propulsion force is automatically achieved during assembly, eliminating the need for post-assembly adjustments and maintaining positioning accuracy throughout the motor's operational life.

Inventive Principle:
Principle #10Preliminary action

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 design simplifies the assembly process by eliminating the need for gap adjustments with shims, ensuring accurate and precise positioning of the stator and mover, thereby expediting the assembly of linear motors and enhancing the overall efficiency of component mounting and inspecting apparatuses.

Implementation Method 1

a linear motor which is equipped with a field element and an armature and produces a force causing the field element and the armature to be relatively displaced along a given axial direction by interaction of magnetic fluxes generated between the field element and the armature

Methodology Applied
Scientific EffectMagnetic attraction force: Magnetism

Data Source

PatentEP2234252B1Linear motor, component mounting apparatus, and component inspecting apparatus
Publication Date: 2019.03.20 YAMAHA MOTOR CO LTD
  • EP2234252B1 patent drawingFigure 1
  • EP2234252B1 patent drawingFigure 2
  • EP2234252B1 patent drawingFigure 3

AI summary

The invention relates to a linear motor equipped with a field element and an armature and adapted to produce a force causing the field element and the armature to be relatively displaced along a given axial direction by interaction of magnetic fluxes generated between the field element and the armature during an operation of supplying electric power to the armature. In one typical aspect of the invention, the linear motor is provided with: a stator which is formed as one of the field element and the armature; a mover which is formed as the other of the field element and the armature; a frame member which defines the axial direction; a rail which is adapted to guide the mover allowing only to reciprocate in a linear direction; a first positioning portion which is provided on the frame member to set a fixing position of the stator with respect to the frame member; and a second positioning portion which is provided on the frame member to set a fixing position of the rail with respect to the frame member in such a manner as to allow the mover to reciprocate along the axial direction with a given gap formed between the mover and the stator positioned by the first positioning portion.