Rare-Earth Cobalt Magnet Composition for Variable Field Motor Efficiency
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Solution Overview
Problem
Variable field motors require a permanent magnet with high residual magnetic flux density, low coercive force, and high squareness ratio to achieve efficient operation over a wide range of speeds, but existing magnets fail to meet these criteria effectively.
Innovation Solution
A rare-earth cobalt permanent magnet composed of 23-27% Sm, 1.0-5.0% Cu, 18-25% Fe, 1.5-3.0% Zr, and the remainder Co, with Cu concentration at least twice that of Zr in grain boundary parts, manufactured through specific heat treatment processes to achieve saturation magnetization and high squareness ratio.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a samarium cobalt magnet is used to change magnetic flux, then the magnetic flux can be adjusted, but the residual magnetization remains high (80% or higher) which prevents satisfactory high-torque operation
Solution Approach 1:
The patent applies parameter changes by precisely controlling the composition parameters (Cu content: 1.0-5.0 mass%, Zr content: 1.5-3.0 mass%, Fe content: 18-25 mass%, Sm content: 23-27 mass%) and heat treatment parameters (solution treatment temperature: 1100-1250°C, aging temperature: 600-850°C) to achieve the desired magnetic properties with residual magnetization of 50-70% and high squareness ratio of 60% or higher
Solution Approach 2:
The patent uses composite materials by combining multiple rare-earth elements (Sm, Pr, Nd) with transition metals (Co, Cu, Fe, Zr) in specific proportions to create a composite permanent magnet material that achieves both adjustable magnetic flux and satisfactory high-torque operation performance
2Adaptability or versatility
If alnico magnet is combined with NdFeB magnet to generate variable field, then magnetic flux can be changed, but the coercive force is too small making the magnet difficult to use
Solution Approach 1:
The patent changes the material parameters by using rare-earth cobalt base material with specific composition ranges (Sm: 23-27 mass%, Co: 40-56 mass%, Cu: 1.0-5.0 mass%, Zr: 1.5-3.0 mass%, Fe: 18-25 mass%) and applying specific heat treatment parameters to achieve both variable field capability and adequate coercive force (Hcj: 120-800 kA/m)
Solution Approach 2:
The patent creates a composite material system combining rare-earth elements (Sm, Pr, Nd) with transition metals (Co, Cu, Fe, Zr) where Cu and Zr are concentrated in grain boundary regions to achieve both variable field capability and improved coercive force through the composite structure
3Quantity of substance
If a permanent magnet with high residual magnetization is used, then magnetic flux is maintained, but the squareness ratio is low preventing efficient operation over wide speed range
Solution Approach 1:
The patent applies parameter changes by optimizing the composition parameters (particularly Cu: 1.0-5.0 mass% and Zr: 1.5-3.0 mass%) and heat treatment parameters (solution treatment: 1100-1250°C, aging: 600-850°C) to achieve the optimal balance between residual magnetization (50-70%) and squareness ratio (60% or higher) for efficient operation over wide speed range
Solution Approach 2:
The patent uses composite materials with specific phase composition (2-17 phase: Sm2Co17, 1-5 phase: SmCo5) where Cu and Zr are concentrated in grain boundary regions to achieve both adequate residual magnetization and high squareness ratio, enabling efficient operation from low to high speeds
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 magnet achieves high residual magnetic flux density, low coercive force, and high squareness ratio, enabling efficient operation of variable field motors from low to high speeds with improved energy efficiency.
Implementation Method 1
A rare-earth cobalt permanent magnet consisting of, when a rear-earth element including at least Sm is represented by R, 23 to 27 mass % of R, 1.0 to 5.0 mass % of Cu, 18 to 25 mass % of Fe, 1.5 to 3.0 mass % of Zr, and a remainder consisting of Co and unavoidable impurities
Implementation Method 2
saturation magnetization is equal to or larger than 1.16 T and an intrinsic coercive force Hcj is 240 to 800 kA/m
Implementation Method 3
manufactured through specific heat treatment processes to achieve saturation magnetization and high squareness ratio
Data Source
AI summary
A rare-earth cobalt permanent magnet having excellent magnetic characteristics, a method for manufacturing such a rare-earth cobalt permanent magnet, and a device are provided. A rare-earth cobalt permanent magnet consists of, when a rear-earth element including at least Sm is represented by R, 23 to 27 mass % of R, 1.0 to 5.0 mass % of Cu, 18 to 25 mass % of Fe, 1.5 to 3.0 mass % of Zr, and a remainder consisting of Co and unavoidable impurities, in which the rare-earth cobalt permanent magnet includes a plurality of crystal grains and grain boundary parts, and a concentration of Cu is at least two times a concentration of Zr in the grain boundary parts.