Switchable Permanent Magnet Unit With Rotating NdFeB Magnets
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Solution Overview
Problem
Existing electro-permanent magnet (EPM) devices require excessive power to switch between magnetization states due to low coercivity of AlNiCo magnets, limiting their application range and efficiency, especially in poorly loaded magnetic circuits, and they suffer from high power consumption and reduced portability.
Innovation Solution
A switchable permanent magnetic unit with a pair of identical, diametrically magnetized cylindrical NdFeB magnets and a solenoid coil system that allows for efficient torque application by rotating one magnet relative to the other, reducing the need for continuous power and enhancing coercivity, thereby improving magnetic flux density and holding force.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If AlNiCo magnets are used in electro-permanent magnet devices, then the devices can be switched between magnetization states, but the coercivity is low causing excessive power consumption
Solution Approach 1:
The patent changes the material parameter from AlNiCo to NdFeB permanent magnets, which have higher coercivity. This material substitution fundamentally alters the magnetic properties, enabling the device to maintain magnetization states with lower power consumption while preserving the switching capability through the solenoid coil system.
Solution Approach 2:
The invention employs a composite magnetic system combining NdFeB permanent magnets with soft magnetic materials in the yoke and pole pieces. This composite structure leverages the high coercivity of NdFeB for stable magnetization while utilizing the soft magnetic properties of the yoke for efficient flux conduction, resolving the contradiction between reliability and power consumption.
2Adaptability or versatility
If AlNiCo magnets are used with low coercivity, then switching is possible, but the application range is limited and portability is reduced
Solution Approach 1:
By changing the material parameter from AlNiCo to NdFeB, the device achieves higher coercivity which reduces the power requirements for switching and holding magnetization states. This enables greater portability and expands application range to include poorly loaded magnetic circuits where the higher coercivity provides stable operation.
3Reliability
If continuous power is applied to maintain magnetization, then the magnetic field is stable, but power consumption increases
Solution Approach 1:
The NdFeB permanent magnets provide self-sustaining magnetization due to their high coercivity, eliminating the need for continuous power application. The magnets maintain their magnetization states autonomously, with power only required transiently during switching operations, thereby achieving both stability and energy efficiency.
Solution Approach 2:
The high coercivity parameter of NdFeB magnets fundamentally changes the energy requirements from continuous power supply to transient power application only during switching, resolving the contradiction between magnetic field stability and power consumption.
4Force
If the magnetic circuit is poorly loaded, then AlNiCo magnets cannot maintain sufficient field strength, but using stronger magnets increases power requirements
Solution Approach 1:
The patent changes the material parameter to NdFeB magnets with inherently higher coercivity and remanence, which maintain sufficient field strength in poorly loaded magnetic circuits without requiring increased power input. The higher material properties enable effective operation across a broader range of loading conditions.
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 solution significantly reduces power consumption during switching, enhances magnetic flux density, and expands the application range by maintaining high coercivity, even in unfavorable magnetic circuits, leading to more efficient and flexible electrically actuated switchable permanent magnet systems.
Implementation Method 1
at least one conductive coil arranged about the second permanent magnet and configured to generate a magnetic field in response to a current being transmitted through the at least one conductive coil
Implementation Method 2
a first permanent magnet mounted within the housing and having an active N-S pole pair; a second permanent magnet rotatably mounted within the housing in a stacked relationship with the first permanent magnet and having an active N-S pole pair
Data Source
AI summary
A switchable permanent magnetic unit is disclosed. The unit comprises: a housing, first and second permanent magnets, and a conductive coil. The first magnet is mounted within the housing and the second magnet is rotatable between first and second positions and mounted within the housing in a stacked relationship with the first magnet. The unit generates a first level of magnetic flux at a workpiece contact interface when the second magnet is in the first position and a second level of magnetic flux at the interface when the second magnet is in the second position, the second level being greater than the first level. The conductive coil is arranged about the second magnet and generates a magnetic field. A component of the conductive coil's magnetic field is directed from S to N along the second magnet's N-S pole pair when the second magnet is in the first position.