Synchronous Linear Motor Cogging Thrust Reduction
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Solution Overview
Problem
Existing linear motors face challenges in reducing cogging thrust while maintaining stroke and thrust density due to increased body size and mass from auxiliary segment cores, leading to reduced acceleration.
Innovation Solution
A synchronous linear motor design without auxiliary segment cores on the movable element, featuring permanent magnets with varying thicknesses or magnetic characteristics along the moving direction to adjust cogging thrust phases, thereby reducing cogging thrust without increasing mass or reducing stroke.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If auxiliary segment cores with permanent magnets are arranged on both end sides of the movable element, then cogging thrust is reduced, but body size of the movable element increases and stroke is reduced
Solution Approach 1:
The invention extracts and removes the auxiliary segment cores from the movable element structure. Instead of adding auxiliary segment cores with permanent magnets at both ends to reduce cogging thrust, the patent eliminates these auxiliary components entirely and achieves cogging thrust reduction through different means (optimizing the arrangement of permanent magnets on the actual segment cores), thereby preventing the increase in body size and loss of stroke.
Solution Approach 2:
The invention applies local quality by arranging permanent magnets with different magnetic characteristics or shapes at specific locations on the segment cores. The patent specifies that permanent magnets at different positions (e.g., end segment cores versus intermediate segment cores) have different properties, allowing localized optimization to reduce cogging thrust without requiring additional auxiliary structures that would reduce stroke.
2Object-generated harmful factors
If auxiliary segment cores with permanent magnets are arranged on both end sides of the movable element, then cogging thrust is reduced, but mass of the movable element increases and thrust density is reduced
Solution Approach 1:
The invention extracts and removes the auxiliary segment cores from the movable element structure. Instead of adding auxiliary segment cores with permanent magnets at both ends to reduce cogging thrust, the patent eliminates these auxiliary components entirely and achieves cogging thrust reduction through different means (optimizing the arrangement of permanent magnets on the actual segment cores), thereby preventing the increase in mass and loss of thrust density.
Solution Approach 2:
The invention applies local quality by arranging permanent magnets with different magnetic characteristics or shapes at specific locations on the segment cores. The patent specifies that permanent magnets at different positions (e.g., end segment cores versus intermediate segment cores) have different properties, allowing localized optimization to reduce cogging thrust without requiring additional auxiliary structures that would increase mass.
3Length of moving object
If the number of permanent magnets is increased to increase moving distance, then cost increases
Solution Approach 1:
The invention applies parameter changes by varying the magnetic characteristics (such as residual flux density, coercivity, or shape) of permanent magnets at different positions along the movable element. Instead of simply increasing the number of permanent magnets to extend moving distance, the patent optimizes the distribution and properties of existing permanent magnets, allowing different regions to serve different functions and thereby extending the effective moving distance without a proportional increase in the number of permanent magnets.
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 effectively suppresses cogging thrust, maintains stroke, and preserves thrust density, enhancing acceleration performance by adjusting magnetic flux densities and phases of cogging thrust vectors.
Implementation Method 1
The movable element has a configuration in which a coil is wound around each of teeth of a plurality of segment cores each formed of a magnetic body. The stator includes an iron core formed of a magnetic body and permanent magnets magnetized in a space direction.
Implementation Method 2
The movable element has a configuration in which a coil is wound around each of teeth of a plurality of segment cores each formed of a magnetic body
Data Source
AI summary
A synchronous linear motor, including: a stator including projecting poles including magnetic bodies; and a movable element arranged opposed to the projecting poles through a space. The movable element includes a core with a magnetic body, coils, and permanent magnets arrayed along a moving direction. The core includes core backs and teeth projecting from the core backs toward the projecting poles. The coils are at least wound around the teeth on both end sides in the moving direction. The permanent magnets are arranged at center portions of the teeth along a projecting direction of the teeth. A polarity of a magnetic pole of the permanent magnet is the same as a polarity of an opposed magnetic pole in an adjacent permanent magnet. The number of different shapes of the permanent magnets or the number of different magnetic characteristics of the permanent magnets is two or more.