Nested Ball-Nut Eddy Current Damper for Compact Vibration Control
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Solution Overview
Problem
Eddy current dampers described in prior patents face challenges such as large size, susceptibility to dust entry, and temperature-related issues, particularly due to the arrangement of permanent magnets and the movement of components, which affect their efficiency and reliability in vibration control.
Innovation Solution
The eddy current damper design includes a screw shaft with first and second permanent magnets arranged circumferentially, a cylindrical magnet holding member, and a conductive member with a ball nut that meshes with the screw shaft, allowing for reduced size and weight while maintaining effective damping through eddy current generation, with components like bearings supporting the magnet holding member to maintain a constant gap and facilitate cooling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the ball nut moves in the axial direction of the screw shaft to ensure movable range, then the damping function is achieved, but the damper size increases
Solution Approach 1:
The ball nut is positioned inside the magnet holding member and conductive member, creating a nested structure where the ball screw mechanism is contained within the magnetic field generation components. This nesting allows the ball nut's axial movement to occur within the existing structural envelope rather than requiring additional external space, thereby achieving the required movable range for damping while preventing overall damper size increase
2Ease of repair
If the guide nut is provided outside the drum, then the maintenance frequency is reduced, but dust entry between the guide nut and ball screw occurs
Solution Approach 1:
Instead of positioning the ball nut externally as in conventional designs, the invention inverts the arrangement by placing the ball nut inside the magnet holding member and conductive member. This inverted configuration protects the ball screw interface from external dust contamination while still allowing the ball nut to move axially for damping operation, thus eliminating dust entry issues while maintaining low maintenance requirements
3Strength
If the cylindrical portion of the guide nut extends toward the opposite side of the drum, then the structural integrity is maintained, but the distance between the end of the cylindrical portion and fixture increases
Solution Approach 1:
The ball nut is nested within the magnet holding member and conductive member, with its cylindrical portion containing the ball screw interface. This nested arrangement allows the structural components to be compactly organized, reducing the overall distance from the end of the cylindrical portion to the fixture while maintaining structural integrity through the integrated design
4Reliability
If permanent magnets are arrayed to generate magnetic field, then eddy current damping is achieved, but the damper size increases
Solution Approach 1:
The invention merges the magnetic field generation function with the structural support function by integrating the permanent magnets into the magnet holding member that also serves as a structural component. The magnets are arranged on the outer peripheral surface of the magnet holding member, combining the magnetic circuit requirements with the mechanical support structure, thereby achieving effective eddy current damping without increasing the overall damper volume
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 enables a compact, lightweight eddy current damper with enhanced damping performance, reduced maintenance needs, and efficient cooling, addressing the size and temperature-related issues of previous designs.
Implementation Method 1
When the conductor rod moves in the axial direction, the magnetic flux passing through the conductor rod from the plurality of permanent magnets changes, and an eddy current is generated on the surface of the conductor rod.
Implementation Method 2
the magnetic flux passing through the conductor rod from the plurality of permanent magnets changes, and an eddy current is generated on the surface of the conductor rod
Implementation Method 3
a plurality of ring-shaped permanent magnets arrayed in the axial direction of the conductor rod
Data Source
AI summary
An eddy current damper includes a screw shaft, first permanent magnets, second permanent magnets, a cylindrical magnet holding member, a cylindrical conductive member, and a ball nut meshing with a screw shaft. The screw shaft is movable in the axial direction. The first permanent magnets are arrayed along the circumferential direction around the screw shaft. The second permanent magnet is arranged between the first permanent magnets, wherein the arrangement of magnet poles is inverted between the second permanent magnet and the first permanent magnet. The magnet holding member holds the first permanent magnet and the second permanent magnet. The conductive member is opposed to the first permanent magnets and the second permanent magnets with a gap therebetween. The ball nut is disposed inside the magnet holding member and the conductive member, and is fixed to the magnet holding member or the conductive member.