Linear Electromagnetic Actuator with Axial Gaps
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Solution Overview
Problem
Linear electromagnetic shakers face challenges due to radial gaps, which complicate assembly, increase friction and wear, and reduce magnetic bias across the axial gaps, leading to non-linear force output and reduced reliability.
Innovation Solution
The design eliminates radial gaps and uses only one pair of axial gaps, with top and bottom radially polarized permanent magnet rings and a drive coil positioned between inner and outer flux cylinders, creating a compact and reliable electromagnetic inertial force generator. Magnetic flux loops with bias flux in opposite directions across air gaps and coil flux in the same direction, resulting in a net force linear with current.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If radial gaps are included between stator and permanent magnets, then assembly is simplified, but friction and wear increase and reliability decreases
Solution Approach 1:
The patent removes the radial gap between the stator and permanent magnets, extracting the problematic air gap from the system. This eliminates the source of friction and wear on support bearings while maintaining assembly simplicity through direct contact or minimal spacing between components.
2Ease of manufacture
If radial gaps are included between stator and permanent magnets, then assembly is simplified, but magnetic bias across axial gaps is reduced
Solution Approach 1:
By removing the radial gap, the magnetic flux path is shortened and strengthened, allowing sufficient magnetic bias to be achieved across the axial gaps without requiring a radial gap. The direct coupling improves magnetic coupling while simplifying assembly.
3Force
If two pairs of axial gaps are included, then linear force output is achieved, but axial length increases
Solution Approach 1:
The patent combines the functions of two pairs of axial gaps into a single pair of axial gaps by using radially polarized permanent magnets arranged to provide magnetic bias in opposite directions across the same gap region. This merging achieves linear force output while reducing axial length.
Solution Approach 2:
The patent uses asymmetric arrangement of radially polarized permanent magnets with alternating polarity around the circumference, creating opposite magnetic bias directions across the axial gap. This asymmetric magnet configuration enables linear force generation in a compact single-gap design.
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 enhances compactness and reliability by minimizing friction, reducing magnetic material usage, and ensuring linear force output with current, while maintaining efficiency and reducing inductance.
Implementation Method 1
drive coil positioned radially between the inner and outer flux cylinders and axially between the top and bottom magnet rings
Implementation Method 2
The combination of bias flux and coil flux cancels in one gap and adds in the other gap because the bias flux is in opposite directions across gaps while the coil flux is in the same direction. Thus, there is net force on the inertial mass
Implementation Method 3
top and bottom radially polarized permanent magnet rings between and in contact with an inner flux cylinder and an outer flux cylinder
Implementation Method 4
Magnetic flux from the top and bottom magnet rings pass through the outer flux cylinder, across the air gaps, through the stationary flux returns, back across the air gaps, and through the inner flux cylinder back to the magnet rings to complete a flux loop
Data Source
AI summary
An electromagnetic inertial force generator provides a linear output with improved compactness and reliability because it has no radial gaps and only one pair of axial gaps. Radial permanent magnet rings are directly in contact with inner and outer flux cylinders to provide magnetic bias. The magnetic bias flux flows across two axial air gaps to a supporting flux return structure. A current conducting coil drives magnetic flux across the same axial air gaps. The magnetic bias flux is in opposite directions across the two air gaps, while the coil flux across the two gaps is in the same direction. The combination of bias flux and coil flux cancels in one gap and adds in the other gap, producing a net force on an inertial mass and an equal and opposite force on the supporting structure. The resulting force is linear with current through the drive coil.