Patent ID: 7219752
Filing Date: 2007-05-22
Classification: E21B,F16F

Abstract:
1. A valve assembly for damping vibration of a drill bit during underground drilling operations, comprising: a first member capable of being mechanically coupled to the drill bit so that the first member is subjected to vibration from the drill bit; a supply of magnetorheological fluid; a second member capable of being mechanically coupled to a source of drilling torque, the second member being mechanically coupled to the first member so that the second member can translate in relation to the first member along a longitudinal centerline of the valve assembly and the first and second members rotate in response to the drilling torque, the first and second members defining a first and a second chamber for holding the magnetorheological fluid, the first and second chambers being in fluid communication; and a coil proximate to one the first and the second members so that the magnetorheological fluid can be subjected to a magnetic field generated by the coil.