Patent ID: 8240401
Filing Date: 2012-08-14
Classification: E21B,F16F

Abstract:
1. A vibration damping system for use in a drill string having a drill bit for drilling a bore hole in an earthen formation, comprising: a first member and a second member, said second member concentrically arranged with respect to said first member and coupled to the first member so that the first member can move axially in an up-hole and a down-hole direction in relation to the second member along an axis of said first and second members and so that torque can be transferred between the first and the second members, one of said first and second members adapted to be coupled to a source of torque for rotating said drill string and the other of said first and second members adapted to be coupled to said drill bit, at least one helical groove formed in at least one of said first and second members for coupling said first and second members to each other so that relative rotation between said first and second members results in relative axial motion between said first and second members in the up-hole or down-hole direction along the axis of said first and second members; and a spring assembly comprising (i) third and fourth members, the fourth member concentrically arranged with respect to said third member, said third member coupled to the first member so that the third member of the spring assembly moves axially in the up-hole and down-hole directions with the first member; said fourth member coupled to the second member so that the fourth member of the spring assembly moves axially in the up-hole and down-hole directions with the second member; and (ii) a spring element for resisting relative movement between the third and fourth members of the spring assembly, wherein said relative rotation between said first and second members that results in axial motion between said first and second members in at least one of said up-hole and down-hole directions is resisted by said spring element.