Electromagnetic Inertial Actuator Arc Flexure Vibration Control
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Solution Overview
Problem
Existing electromagnetic inertial actuators for active vibration control, such as those using cylindrical voice coil motors and folded flexure systems, face limitations in efficiently counteracting structural vibrations, particularly in achieving large excursions and output forces at frequencies matching the natural frequency of the spring-mass system.
Innovation Solution
The design incorporates a parallel arrangement of flexure parts and a voice coil motor with a magnet and coil, where the magnet part is driven to move in an arc relative to the support base, utilizing a cantilevered configuration with composite flexure stacks and elastomeric shims to enhance flexibility and output force, allowing curvilinear motion and large strokes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If a cylindrical voice coil motor with folded flexure system is used, then the actuator can generate vibration control force, but the excursion and output force are limited at natural frequency
Solution Approach 1:
The patent employs an arc-shaped flexure stack instead of a linear configuration. The curved geometry allows the moving mass to traverse a larger arc length while maintaining compact radial dimensions, thereby increasing excursion without proportionally increasing the overall actuator size. The arc shape optimizes the force vector alignment with the displacement direction throughout the motion range.
Solution Approach 2:
The invention transitions from a linear voice coil motor configuration to a radial/arc-based configuration. By arranging the flexure stack in an arc shape and positioning the voice coil motor radially, the system exploits the radial dimension to achieve larger excursions through arc length while maintaining a compact overall footprint, effectively trading linear dimension for curved path length.
2Force
If the actuator is designed for large excursions, then vibration counteraction capability improves, but moment loads on flexure clamps increase
Solution Approach 1:
The arc-shaped flexure stack distributes the mechanical loads more favorably compared to a linear configuration. The curved geometry naturally redirects moment loads along the arc, reducing concentrated stresses at the clamp connections. The distributed curvature allows large excursions while maintaining lower peak moment loads at the support points.
3Force
If a parallel arrangement of flexure parts is used, then flexibility and output force are enhanced, but device complexity increases
Solution Approach 1:
The patent integrates multiple functions into the arc-shaped flexure stack structure. The same curved flexure elements that provide the extended excursion path also serve as the spring support elements and moment-load-bearing components. This merging of functions achieves enhanced output force and flexibility without proportionally increasing structural complexity, as a single geometric feature (the arc shape) accomplishes multiple mechanical objectives.
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 enables significant excursions and high output forces when the alternating current frequency matches the natural frequency, effectively counteracting structural vibrations with improved force generation and reduced moment loads on the flexure clamps.
Implementation Method 1
The coil part has a coil. The magnet part is driven by the coil part whereby the magnet part moves in an arc relative to the support base
Implementation Method 2
The first flexure part comprises a first flexure stack and the second flexure part comprises a second flexure stack. The parallel arrangement is cantilevered from the support base. The first flexure part has an opposing first end and second end and the second flexure part has an opposing first end and second end, the first ends are coupled to the support base and the second ends are coupled to the magnet part
Data Source
Figure 1
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Figure 3
AI summary
An electromagnetic inertial actuator includes a support base (3) and a parallel arrangement (5) of a first flexure part (7), a voice coil motor part (9), and a second flexure part (11). The parallel arrangement (5) is cantilevered from the support base (3).