Linear Compressor Ferrite Magnet Flux Leakage
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Solution Overview
Problem
Conventional linear compressors face issues with magnetic flux leakage and efficiency due to the use of rare-earth magnets, leading to damaged connection parts and reduced compressor efficiency when trying to minimize the size of these components.
Innovation Solution
The design incorporates a ferrite-based permanent magnet and a stainless steel coupling plate, with a specific configuration that includes a side extension part and flange part to enhance the delivery of magnetic force without leakage, and uses nonmagnetic materials for the cylinder and piston to prevent flux loss, along with an intermediate supporting member to prevent damage during reciprocation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If rare-earth magnets (neodymium magnets) are used to increase magnetic flux density, then the driving force of the linear motor is improved, but magnetic flux leaks through the coupling plate made of magnetic material, causing damage to connection parts and reducing compressor efficiency
Solution Approach 1:
A nonmagnetic intermediate member is introduced between the permanent magnet and the coupling plate to prevent magnetic flux from leaking through the coupling plate. This intermediary component blocks the harmful magnetic flux path while allowing mechanical force transmission, thereby protecting the connection parts from damage and improving compressor efficiency
Solution Approach 2:
The patent replaces expensive rare-earth magnets with ferrite-based permanent magnets that are cheaper and sufficiently durable for the application. While ferrite magnets have lower magnetic flux density than neodymium magnets, they provide adequate driving force without causing severe magnetic flux leakage issues, offering a cost-effective solution with sufficient service life
2Device complexity
If the size of connection parts is reduced to minimize component dimensions, then device complexity and size are improved, but the connection parts become more susceptible to damage from magnetic flux leakage and reciprocating forces
Solution Approach 1:
The nonmagnetic intermediate member acts as a protective intermediary that distributes and absorbs the reciprocating forces and magnetic flux effects, allowing the use of smaller connection parts without compromising their durability. The intermediate member shields the connection parts from direct exposure to harmful magnetic flux and mechanical stress concentrations
3Force
If the permanent magnet is positioned closer to the coupling plate to reduce distance, then the force transmission efficiency is improved, but magnetic flux leakage through the coupling plate increases, damaging connection parts
Solution Approach 1:
The nonmagnetic intermediate member is positioned between the permanent magnet and coupling plate, allowing the magnet to be placed close to the coupling plate for efficient force transmission while the intermediate member blocks the magnetic flux leakage path. This intermediary enables close positioning without the harmful effects of direct magnetic flux contact
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 improves the compressing efficiency and reliability of the linear compressor by reducing magnetic flux leakage and extending the lifespan of components, while also lowering manufacturing costs through the use of cheaper ferrite-based magnets and nonmagnetic materials.
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
uses nonmagnetic materials for the cylinder and piston to prevent flux loss
Data Source
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Figure 3
AI summary
A linear compressor (10) includes a shell (100) in which a refrigerant suction part (101) is disposed. A cylinder (120) is provided inside the shell. A piston (130) reciprocates inside the cylinder. A motor assembly (200) provides a driving force for movement of the piston. A magnet assembly (300) delivers the driving force exerted by the motor assembly to the piston. The magnet assembly (300) includes a magnet frame (310) having a cylinder shape. A permanent magnet (350) is installed in the magnet frame. A coupling plate (330) is coupled one side of the magnet frame and includes a flange part (335) coupled to an end portion of the permanent magnet.