Cardan Pendulum Suspension With Eddy-Current Damping at Low Speeds
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Solution Overview
Problem
Existing pendulum dampers for tall and slender structures, such as wind turbines, face challenges in achieving sufficient damping for low kinetic energy conditions and low space requirements, particularly at natural frequencies below 10 Hz, due to limitations in magnetic dampers which are direction-dependent and insufficient at slow movements.
Innovation Solution
The implementation of a pendulum suspension with a Cardan joint and eddy-current rotating components, featuring a transmission gearing that increases rotational speed and damping force, allowing for adaptive influence on natural frequencies through optional additional rotating mass, thereby achieving high damping densities without the space and cost constraints of traditional magnetic dampers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If conventional magnetic dampers are used, then damping is achieved through attraction or repulsion of magnets, but the damping is insufficient at low speeds and direction-dependent
Solution Approach 1:
The patent replaces conventional magnetic dampers with eddy current dampers that use electromagnetic induction instead of direct magnetic attraction/repulsion. A conductor element rotates through a magnetic field generated by permanent magnets, inducing eddy currents that create opposing magnetic fields for damping. This substitution eliminates direction-dependency and improves low-speed effectiveness.
Solution Approach 2:
The patent introduces a transmission gearing system with transmission ratio between 5:1 and 500:1 that converts the slow linear movement of the pendulum mass into rapid rotation of the conductor element. This dimensional transformation from linear to rotational motion with speed multiplication enables the conductor to achieve high rotational speeds (4-400 times faster than pendulum movement) for effective eddy current damping.
2Power
If transmission gearing is added to increase rotational speed, then damping force is enhanced, but device complexity increases
Solution Approach 1:
The Cardan joint (universal joint) serves multiple functions simultaneously: it accommodates angular misalignments between the pendulum rod and transmission gearing, transmits rotational motion through varying angles, and connects the linear pendulum movement to the rotational conductor element. This multi-functionality reduces the need for additional alignment components.
Solution Approach 2:
The transmission gearing system is designed to dynamically adapt to the varying speeds and torques produced by the pendulum during different phases of vibration. The gearing ratio can be optimized for different operating conditions, and the system naturally adjusts its mechanical advantage as the pendulum moves through its arc, providing consistent damping force across varying vibration amplitudes.
3Power
If eddy current dampers with high rotational speed are used, then damping density increases, but space requirements increase
Solution Approach 1:
The patent employs a compact nested arrangement where the conductor element rotates within a magnetic field generated by permanent magnets arranged in a circular pattern. The transmission gearing is integrated into the same housing as the eddy current damping components, with the Cardan joint connecting directly to the gearing input. This nesting minimizes the overall footprint while maintaining high damping density through the concentrated magnetic field and rapid conductor rotation.
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 solution provides a high damping effect that is independent of direction and effective at low speeds, achieving approximately 4-400 times the speed of rotating conductor elements compared to stationary magnetic elements, thus overcoming the limitations of traditional dampers in terms of damping density and space efficiency.
Implementation Method 1
a rotating component, in particular a conductor disk, which has a relative movement with respect to magnetic elements or a magnetic field, as a result of which an eddy current is generated which generates a force that opposes the force moving the pendulum
Implementation Method 2
Eddy current dampers are functionally based on the fact that a current is induced in an electrical conductor that moves through an alternating magnetic field
Implementation Method 3
a pendulum suspension which has a universal or Cardan joint and at least one eddy-current rotating component on each shaft of the joint
Implementation Method 4
connecting, upstream, at least one transmission gearing between the universal joint (Cardan joint) and the eddy-current rotating component
Data Source
AI summary
A new type of independently damping pendulum suspension for pendulum dampers for use in tall slender constructions and technical installations, more particularly used in wind turbines. A Cardan joint is equipped with damping elements and mounted at the other end opposite the pendulum mass. The Cardan joint is able, despite the small motions, to sufficiently damp the oscillations of the pendulum produced by disturbing frequencies.