Patent ID: 6009982
Filing Date: 2000-01-04
Classification: B60G,F16F

Abstract:
A helicopter rotor assembly comprising:a) a rotating yoke member having a damper-attachment portion;b) a blade member connected to said yoke member and having a damper-attachment portion disposed a distance from said damper-attachment portion of said yoke member;said blade member being movable with respect to said yoke member to define a range of distances between said damper-attachment portions of said blade member and said yoke member;c) a magnetic particle damper including:a first conductor member being attached to said damper-attachment portion of one of said yoke member and blade member;said first conductor member having a magnetically permeable portion being a first part of a magnetic flux path;a second conductor member being attached to said damper-attachment portion of another one of said yoke member and blade member and being spaced-apart from said first conductor member to define a gap therebetween;said second conductor member having a magnetically permeable portion being a second part of said magnetic flux path;said magnetically permeable portions of said first and second conductor members each including a flux terminal region;said flux terminal regions of said first and second conductor members confronting one another across said gap;a frame being connected between said first and second conductor members;said frame maintaining said gap between said first and second conductor members and limiting relative movement between said first and second conductor members to substantially translational motion;a quantity of dry magnetic particles disposed within said gap between said first and second conductor members;said magnetic particles between said flux terminal regions of said first and second conductors being a third part of said magnetic flux path; anda magnetic element fixedly attached to the magnetically permeable portion of one of said first and second conductor members;said magnetic element having magnetic poles and producing a magnetic field therebetween;said magnetic field having a high flux density along said magnetic flux path;said magnetic particles along said flux path being influenced by said magnetic field to magnetically adhere to adjacent magnetic particles and to said first and second conductor members to produce a force opposing relative motion between said damper attachment portions and to dissipate energy when said distance between said damper-attachment portions of said yoke member and said blade member changes;whereby oscillations in the lead-lag direction between said yoke member and said blade member are damped by said magnetic particle damper.