Slotted Beam Piezoelectric Composite for Energy Harvesting
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Solution Overview
Problem
Existing energy harvesting systems from vibrating structures, such as vehicles, face inefficiencies due to non-uniform strain distribution across piezoelectric elements, leading to power dissipation and reduced energy output.
Innovation Solution
A composite structure with a slotted cantilever beam spring and piezoelectric elements bonded to elevated portions, providing a larger separation distance and reduced effective thickness, which increases strain and energy transfer to piezoelectric elements, while maintaining low friction losses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If piezoelectric elements are mounted on a rectangular cantilever beam spring, then the structure is simple to manufacture, but the strain distribution across the piezoelectric elements is non-uniform, leading to power dissipation and reduced energy output
Solution Approach 1:
The beam spring is designed with a non-uniform cross-section (tapered width or thickness) to create a specific strain distribution pattern. This local variation in geometry ensures that the strain across the piezoelectric element mounting surface is uniform, optimizing energy harvest while maintaining manufacturing feasibility through standard machining processes
Solution Approach 2:
The patent modifies the geometric parameters of the beam spring (width, thickness, or curvature profile) to transform the strain distribution from non-uniform to uniform. By changing these physical parameters, the system achieves higher power output without fundamentally altering the manufacturing process
2Power
If the beam width is varied to achieve uniform strain distribution, then the energy harvesting efficiency improves, but the device complexity increases
Solution Approach 1:
The beam spring incorporates localized geometric variations (tapered sections or curved profiles) only in the regions where strain distribution needs optimization. The rest of the beam maintains a simple rectangular cross-section, minimizing overall device complexity while achieving uniform strain where the piezoelectric elements are mounted
3Stress or pressure
If piezoelectric elements are placed closer to the base of the beam, then the strain magnitude increases, but the separation distance between elements decreases, reducing effective energy transfer
Solution Approach 1:
The patent optimizes the beam's cross-sectional parameters (width and thickness) as functions of position along the beam length. By varying these parameters, the system achieves high strain magnitude near the base while maintaining sufficient separation distance between piezoelectric elements through appropriate sizing of the elevated portions
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 results in increased power output and improved energy harvesting efficiency by maximizing strain and amplitude of vibration in piezoelectric elements, enhancing the overall energy harvesting capability.
Implementation Method 1
Harvesting energy from a vibrating structure, such as a vehicle, has involved mounting piezoelectric (PZT) elements along with a proof mass to provide a vibrating beam
Data Source
AI summary
One aspect of the present patent application is an energy harvesting device comprising a composite structure including a base spring and a piezoelectric structure. The base spring has a base spring surface having elevated portions separated by a recessed portion. The piezoelectric structure substantially crosses the recessed portion. In one aspect the piezoelectric structure includes a piezoelectric element that is bonded to the elevated portions. In another aspect, the base spring has a base spring stiffness. The piezoelectric element has a piezoelectric element stiffness. The base spring stiffness is less than the piezoelectric element stiffness. In another aspect, the composite structure has a natural frequency of vibration, and this natural frequency of vibration of the composite structure is automatically adjustable. In another aspect, the piezoelectric elements are stacked. In another aspect, the piezoelectric structure is located in the recessed portion.