Rotational Energy Harvester with Active Rotor Stabilization
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Solution Overview
Problem
Existing rotational energy harvesting devices for motor vehicle tires face limitations in power output due to rotor co-rotation under varying conditions, large installation footprint, and unsuitability for tire pressure monitoring, as they are prone to damage from centrifugal forces and have inefficient energy generation.
Innovation Solution
The apparatus detects the position of the rotor's center of gravity relative to the rotation axis and uses current flow to stabilize the rotor, limiting deflection and preventing co-rotation, allowing for efficient energy generation even under changing conditions, with a compact design suitable for tire applications.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If the rotor is allowed to deflect 90° from the resting position to achieve maximum power output, then the electrical power generated is maximized, but the rotor becomes susceptible to co-rotation and damage from centrifugal forces
Solution Approach 1:
The control circuit continuously monitors the rotor position and adjusts the magnetic field strength dynamically. When the rotor approaches 90° deflection, the control circuit reduces the magnetic field strength to prevent co-rotation, creating a feedback loop that maintains optimal power generation while ensuring rotor stability
Solution Approach 2:
The magnetic field strength is made dynamic rather than static, varying with rotor position and operating conditions. The control circuit adjusts the excitation current to the coil based on real-time rotor position, allowing the system to adapt between maximum power mode and stability mode
2Power
If the rotor eccentricity is increased to enhance power generation capability, then the maximum attainable electrical power increases, but the rotor becomes more vulnerable to damage from centrifugal forces
Solution Approach 1:
The control circuit monitors rotor position and centrifugal force effects, dynamically adjusting the magnetic field strength to compensate for increased rotor eccentricity. This feedback mechanism allows the system to exploit higher eccentricity for greater power while preventing centrifugal force damage through active control
Solution Approach 2:
The system changes the magnetic field strength parameter dynamically based on rotor position and operating conditions. By adjusting this parameter, the system can accommodate higher rotor eccentricity values that enable greater power generation while maintaining stability through controlled magnetic field variations
3Power
If the apparatus is designed with a larger footprint to generate adequate voltage, then the power generation capability improves, but the installation space requirement increases making it unsuitable for tire applications
Solution Approach 1:
The system achieves higher voltage output from a compact size by optimizing magnetic field strength parameters and coil configuration. The control circuit enables the apparatus to generate adequate voltage at lower rotational speeds, allowing a smaller stator diameter while maintaining power generation capability
Solution Approach 2:
The dynamic adjustment of magnetic field strength allows the compact apparatus to compensate for its smaller size by intensifying the magnetic field when needed, enabling adequate voltage generation from a reduced installation footprint suitable for tire applications
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 approach enables reliable and efficient electrical energy generation in motor vehicle tires, preventing rotor damage and achieving a high power output while maintaining a small installation footprint, suitable for tire pressure monitoring and other applications.
Implementation Method 1
a coil is arranged for inducing an electrical voltage when the stator is rotated relative to the rotor
Implementation Method 2
a device for generating a magnetic field, typically one or more permanent magnets or an excitation winding, is provided in the rotor
Implementation Method 3
the rotor which can rotate freely and is connected to the stator has a defined resting position in which the center of gravity of the rotor is located perpendicularly below the rotation axis. Thus, when the stator is rotated, the rotor is stabilized in the resting position by the eccentric center of gravity in combination with the gravitational force acting on the rotor
Implementation Method 4
a co-rotation by the rotor would result in damage to the rotor, which in contrast to the stator is not designed for such large centrifugal forces
Data Source
AI summary
The invention relates to a device (1) for generating electrical energy from a rotational movement, comprising a stator (3) which can rotate about a rotational axis and a rotor (4) which can rotate about the rotational axis (2) and is connected to the stator (3), which rotor comprises a centre of gravity (5) located outside the rotational axis (2), wherein in the stator (3) a coil is arranged for inducing an electrical voltage when the stator (3) is rotated relative to the rotor (4), wherein an electrical circuit (7) is connected to the coil, said circuit comprising an energy store (6) for rectifying the voltage induced in the coil. In order to achieve a maximum energy yield under various conditions of use, according to the invention, the device (1) is configured to detect a position of a plane defined by the rotational axis (2) and the centre of gravity (5) of the rotor (4) and to influence the position of the plane by means of a current flow through the coil, so that a deflection of the plane from the vertical can be limited by the current flow during a rotation of the stator (3). The invention also relates to a use of a such a device (1).