Vibration Energy Harvester With Nested Magnetic Core
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Solution Overview
Problem
Existing electromechanical generators face challenges in achieving high mass, high Q factor, and high magnetic coupling for efficient conversion of mechanical vibrational energy into electrical energy over a wide bandwidth, which is essential for powering wireless sensors without the need for power cables or batteries.
Innovation Solution
The design incorporates a housing with a central electrically conductive coil assembly and a movably mounted magnetic core assembly biased by plate springs, featuring a pair of opposed magnets and a common ferromagnetic body, maximizing mass and magnetic coupling while minimizing flux leakage, thereby enhancing electrical power output.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If the mass of the spring-mass combination is increased to achieve high power output, then the device becomes too large and heavy for practical applications
Solution Approach 1:
The magnetic core assembly is nested within the coil assembly, with the magnetic core positioned inside the coil's winding structure. This nested configuration allows the magnetic flux to pass through the coil windings multiple times, effectively increasing the magnetic coupling factor without requiring additional external space or mass. The magnetic core with opposing magnets is contained within the coil's inner diameter, creating a compact integrated structure that maximizes power density.
Solution Approach 2:
The patent transitions from a linear arrangement to a three-dimensional integrated structure where the magnetic core is positioned within the coil's volume. The magnetic flux path is optimized to pass through the coil windings in multiple dimensions, with the magnetic core extending axially and radially within the coil structure. This dimensional optimization increases the magnetic coupling factor without proportionally increasing mass.
2Power
If the magnetic coupling factor is increased to improve power output over wide bandwidth, then the device complexity increases
Solution Approach 1:
The magnetic core assembly and coil assembly are merged into a single integrated unit where the magnetic core is positioned within the coil structure. The opposing magnets on the magnetic core work together with the coil windings to create a unified magnetic coupling system. This merging eliminates the need for separate magnetic assemblies and simplifies the overall structure while achieving high magnetic coupling factor.
Solution Approach 2:
The magnetic core assembly serves multiple functions: it provides the magnetic flux path, acts as the moving mass for vibration harvesting, and contains the opposing magnets that generate the magnetic field. The coil assembly simultaneously serves as the electrical output generator and the structural support for the magnetic core. This multi-functionality reduces the number of separate components needed.
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 allows for a high degree of magnetic coupling and increased moving mass, resulting in improved electrical power generation and the ability to tune resonant frequency accurately, enhancing the device's efficiency and operational bandwidth for energy harvesting applications.
Implementation Method 1
Up and down vibrational movement of the assembly induces an electrical current in the surrounding coil
Implementation Method 2
a biasing device mounted between the housing and the magnetic core assembly to bias the magnetic core assembly in opposed directions along the axis towards a central position
Data Source
Figure 1
Figure 2~3
Figure 4
AI summary
An electromechanical generator for converting mechanical vibrational energy into electrical energy, the electromechanical generator comprising a housing (4), an electrically conductive coil assembly (22, 24) fixedly mounted in the housing (4), a mount for the coil assembly (22, 24) extending inwardly of the radially inner side for fixing the coil assembly (22, 24) in the housing(4), a magnetic core assembly (50) movably mounted in the housing (4) for linear vibrational motion along an axis (A), and a biasing device (82, 84) mounted between the housing (4)' and the magnetic core assembly (50) to bias the magnetic core assembly (50) in opposed directions along the axis, towards a central position, wherein the magnetic core assembly (50) encloses the coil assembly (22, 24) on the radially outer side (23) and on the upper (27) and lower (29) edges, the magnetic core assembly (50) having a gap(55), on a radially inner portion thereof through which the mount (26) extends, and the radially inner portion including two opposed magnets (52, 54), spaced along the axis (A).