Piezoelectric Energy Harvesting Case Design
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Solution Overview
Problem
Existing energy harvesting technologies for portable electronic devices are inefficient due to low energy output from ambient vibrations and require large, stiff piezoelectric bimorphs, which are not well-suited for low-frequency vibrations commonly found in practical applications.
Innovation Solution
A portable apparatus with a case design that includes multiple piezoelectric elements arranged over opposing surfaces, where a second and third case member are movably suspended to interface with the ends of these elements, allowing for efficient energy generation from mechanical vibrations without the need for an external power source.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If a piezoelectric bimorph cantilever is designed with low stiffness to accommodate a large proof mass for energy harvesting, then the device can generate useful voltage from vibrations, but the device becomes relatively large and stiffer, which reduces its ability to respond to low-frequency ambient vibrations
Solution Approach 1:
The patent embeds the piezoelectric elements within the case structure itself, nesting the energy harvesting function inside the existing device housing. The piezoelectric elements are positioned between the first and second case members, utilizing the case's internal space rather than adding external protruding structures. This nesting approach enables voltage generation while maintaining a compact form factor suitable for portable electronic devices.
Solution Approach 2:
The patent transitions from a traditional cantilever configuration (extending in one dimension) to a distributed arrangement of piezoelectric elements between opposing surfaces of the case. By utilizing the third dimension (space between case members) and arranging elements across multiple surfaces, the design achieves effective energy harvesting without increasing the device's external dimensions, thereby maintaining flexibility for low-frequency vibrations.
2Power
If piezoelectric elements are arranged in a traditional cantilever configuration, then voltage can be generated from deflection, but the device requires a large proof mass and low stiffness, making it unsuitable for low-frequency ambient vibrations
Solution Approach 1:
The patent creates a dynamic system where the second case member is movably suspended on the first case member, allowing the structure to adapt its stiffness characteristics in response to varying vibration frequencies. The piezoelectric elements are positioned to experience strain during relative movement between case members, enabling the device to effectively harvest energy across a broader range of vibration frequencies including low-frequency ambient vibrations, rather than being locked into a fixed resonant frequency.
Solution Approach 2:
The case structure serves multiple functions: it provides mechanical housing for the electronic device, acts as the mounting structure for piezoelectric elements, and functions as part of the energy harvesting mechanism itself through the movable suspension system. This multi-functionality eliminates the need for separate dedicated energy harvesting components, allowing the device to maintain adaptability to various vibration conditions while generating useful power.
3Duration of action of moving object
If rechargeable batteries are used to power portable electronic devices, then continuous operation is enabled, but the batteries require external power sources for charging and may be unstable at elevated temperatures
Solution Approach 1:
The patent implements self-service by enabling the electronic device to generate its own charging power through the piezoelectric energy harvesting system. The piezoelectric elements convert mechanical vibrations from the device's normal operation into electrical energy that can be stored in the rechargeable battery, eliminating the need for external charging infrastructure. The device essentially charges itself during use, reducing dependency on external power sources and simplifying the overall system.
Solution Approach 2:
The patent merges the energy harvesting function with the existing case structure and battery system of the portable device. By integrating the piezoelectric elements into the case and connecting them to the battery, the invention combines mechanical vibration energy conversion with electrical energy storage in a unified system, thereby extending operational duration without adding separate charging devices or increasing overall complexity.
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 apparatus effectively converts mechanical vibrations into electrical energy, capable of recharging batteries or powering electronic devices directly, reducing the need for external charging and improving energy harvesting efficiency by utilizing the device's natural motion.
Implementation Method 1
a plurality of piezoelectric elements configured to generate electrical energy from the mechanical vibrations
Data Source
AI summary
An apparatus for generating electrical energy from mechanical vibrations of an object is provided. The apparatus comprises a case for housing the object. The case comprises: a first case member comprising a first and a second opposing surfaces, said first case member comprising an internal space between the first and the second opposing surfaces; multiple piezoelectric elements for generating electrical energy from the mechanical vibrations, each piezoelectric element comprises a first and a second end, wherein each piezoelectric element being arranged over the first and the second opposing surfaces at the first end; a second case member movably suspended on the first case member, said second case member interfaces with the second end of piezoelectric elements arranged over the first opposing surface; and a third case member movably suspended on the first case member, said third case member interfaces with the second end of piezoelectric element arranged over the second opposing surface.