Linear Compressor Three-Pole Ferrite Magnet Design
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Solution Overview
Problem
Linear compressors with single-polarity permanent magnets suffer from insufficient magnetic flux, leading to increased dimensions and manufacturing costs due to the use of rare-earth magnets, which are expensive and inefficient.
Innovation Solution
A linear compressor design featuring a permanent magnet with three poles, including two end magnetic poles and a central magnetic pole, made of ferrite material, which interacts with an outer and inner stator to generate sufficient thrust while minimizing magnetic flux leakage and manufacturing costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single-polarity permanent magnet is used, then the structure is simple, but the magnetic flux is insufficient requiring larger dimensions
Solution Approach 1:
The permanent magnet is divided into three separate polarity regions (N-S-N or S-N-S arrangement) instead of using a single polarity magnet. This segmentation allows the magnet to generate sufficient magnetic flux through the combined effect of multiple polarity interactions with the stator, eliminating the need to increase magnet dimensions while maintaining a compact structure.
Solution Approach 2:
The patent employs an asymmetric magnetic pole arrangement where the central polarity region has a different length than the two end polarity regions. This asymmetric design optimizes the magnetic flux distribution and thrust generation efficiency, allowing the magnet to achieve sufficient force output without increasing overall magnet volume, thereby resolving the contradiction between structural simplicity and magnetic flux sufficiency.
2Quantity of substance
If the permanent magnet dimension is enlarged to compensate for insufficient magnetic flux, then the magnetic flux becomes sufficient, but the manufacturing cost increases sharply
Solution Approach 1:
By segmenting the magnet into three polarity regions, the patent achieves sufficient magnetic flux through optimized magnetic circuit design rather than increasing magnet volume. This allows the use of smaller amounts of expensive rare-earth magnetic material while maintaining adequate thrust generation, thereby reducing manufacturing cost.
Solution Approach 2:
The patent changes the magnetic pole configuration parameters (arranging N-S-N or S-N-S polarities) to optimize magnetic flux generation efficiency. This parameter optimization allows sufficient magnetic flux to be achieved with a compact magnet design, reducing the quantity of expensive rare-earth material required and thereby lowering manufacturing cost.
3Power
If a three-pole permanent magnet is used, then the magnetic flux and thrust are sufficient, but the structure becomes more complex
Solution Approach 1:
The magnet is segmented into three polarity regions arranged in a specific sequence (N-S-N or S-N-S), which generates sufficient thrust through combined magnetic interactions with the stator. This segmentation provides an efficient solution for thrust generation that is more effective than a single-polarity magnet but maintains reasonable structural simplicity through systematic arrangement.
Solution Approach 2:
The three polarity regions are merged into a single integrated permanent magnet component rather than using separate magnets. This merging approach achieves sufficient thrust generation through the combined effect of multiple polarities while maintaining structural simplicity and reducing the number of separate components, thereby resolving the contradiction between power output and structural complexity.
4Power
If the central magnetic pole length is increased, then the thrust generation improves, but the magnet dimension increases
Solution Approach 1:
The patent employs asymmetric pole length design where the central magnetic pole has a different length than the end poles, optimized to achieve sufficient thrust without requiring uniform increases in all pole dimensions. This asymmetric configuration allows the central pole to be extended strategically to improve thrust generation while keeping the overall magnet length compact, thereby resolving the contradiction between power output and dimensional constraints.
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 enhances thrust generation and reduces cogging forces, improving operational efficiency and compactness while using a cost-effective ferrite material, thus addressing the inefficiencies and cost issues of previous designs.
Implementation Method 1
the permanent magnet may be linearly reciprocated by a mutual electromagnetic force between the permanent magnet and the inner (or outer) stator
Implementation Method 2
An amount of magnetic flux generated from the single magnet is insufficient... the permanent magnet with three poles, including two end magnetic poles and a central magnetic pole... interacts with an outer and inner stator to generate sufficient thrust while minimizing magnetic flux leakage
Data Source
AI summary
A linear compressor (10) includes a cylinder (120) forming a compression space for a refrigerant, a piston (130) reciprocatably moving in an axial direction inside the cylinder, and a linear motor (200) supplying a power to the piston. The linear motor includes an outer stator (210) including a first stator magnetic pole (217), a second stator magnetic pole (218), and an opening (219) defined between the first stator magnetic pole and the second stator magnetic pole, an inner stator (220) disposed apart from the outer stator, and a permanent magnet (230) movably disposed in an air gap between the outer stator (210) and the inner stator (220), and having three poles (231,232,233). The three poles include two both-end magnetic poles (231,233), and a central magnetic pole (232) disposed between the two both-end magnetic poles, the central magnetic pole having a length greater than the both-end magnetic poles.