Backpack Energy Harvester with Adjustable Spring and Brushless AC Generator
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Solution Overview
Problem
Existing backpacks for energy generation are heavy, inefficient, and require complex spring adjustments, with limited power output and ergonomic issues, making them unsuitable for prolonged use in field applications.
Innovation Solution
A lighter, more efficient backpack with a single adjustable spring and a geared brushless AC generator, along with electrical damping circuits and additional power-generating devices, such as the E-MOD, to optimize energy harvesting and power management.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If multiple springs are used in the backpack suspension system, then the system can handle varying weights, but the device complexity and difficulty of field adjustment increase significantly
Solution Approach 1:
The spring system is segmented into multiple individual springs that can be independently adjusted or removed. This allows the system to handle varying weights by selectively engaging different springs, while maintaining manageable complexity through modular design.
Solution Approach 2:
The spring configuration is made dynamic and adjustable in the field. Users can modify the spring system on-demand to adapt to different load conditions, transforming a static complex system into a dynamically adaptable one that simplifies operation during use.
2Device complexity
If a DC generator is used, then the system is simpler, but the efficiency and power output are limited to 30-40% efficiency and modest power levels
Solution Approach 1:
The DC generator is replaced with an AC generator system that uses electromagnetic induction principles more efficiently. This substitution enables higher power output and efficiency (70-80%) while maintaining reasonable system complexity through the use of standard AC generation technology.
3Power
If electrical damping circuits are added to control power extraction, then the power management improves, but the device complexity increases
Solution Approach 1:
Electrical damping circuits with feedback control are implemented to regulate power extraction from the generator. The feedback mechanism monitors system state and automatically adjusts electrical loading to optimize power extraction while preventing overdamping, improving power management through intelligent control.
4Manufacturing precision
If the spring constant is fixed, then the manufacturing precision is easier to maintain, but the adaptability to different walking speeds and weights is reduced
Solution Approach 1:
The spring constant is made adjustable rather than fixed. Users can modify the spring configuration in the field to match different walking speeds and load conditions, transforming a precisely manufactured but inflexible system into an adaptable one that maintains performance across varying operational parameters.
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 new backpack achieves up to 20 W of power during walking and 25 W during running with improved efficiency and ergonomic benefits, reducing the need for batteries and minimizing orthopedic injuries.
Implementation Method 1
The spring constant of which can be adjusted in the field in seconds to match the frequency of the wearer's movement
Implementation Method 2
a single adjustable spring
Implementation Method 3
geared brushless AC generator that permits approximately 70%-80% overall efficiency and the generation of up to 20 W of electrical power during walking and 25 W during running
Data Source
AI summary
An electricity-generating backpack that is substantially lighter in weight, has the multiple springs replaced with one large spring whose spring constant can be adjusted in the field in seconds, and replaces a DC generator with a brushless AC generator that permits approximately 70% generator efficiency and the generation of up to 20 W of electrical power by converting mechanical energy to electrical power. A device is provided that always removes some electricity, but not too much, as necessary to extract large levels of the electricity while controlling damping by providing electrical damping circuits including a DC-DC converter designed to emulate a desired load at its input terminals. Additional electricity generating E-MOD devices may be used for generating additional power by hooking an E-Mod device to a generator and to the backpack belt at the wearer's hip and includes a wand that fits against the wearer's femur so as to move through a range of motion as the patient walks. The system also provides multiple possibilities of electricity generation when not walking including a light-weight bicycle ergometer which can be mounted to the backpack frame and generate very high power levels (100 W). The electricity generated and stored by the backpack may be used to charge batteries and to power a number of devices that may be carried by the backpack, such as a Sterling Cooler System that is powered by the backpack's stored power to provide cooling power for cooling items carried by the backpack.