Coupling For Downhole Tools

Abstract

Transferring rotary power between a first rotating member and a second rotating member may performed by using a first element associated with the first rotating member; and a second element associated with the second rotating member. The first element and the second element may be configured to rotate the first rotating member either substantially synchronously or non-synchronously with the second rotating member. A hysteresis material may be utilized in either or both of the first element and the second element. A modulator may be used to control a speed of the first element or the second element.

1 . An apparatus for transferring rotary power between a first rotating member and a second rotating member, comprising:
 a first element associated with the first rotating member; and   a second element associated with the second rotating member, the first element and the second element being configured to rotate the first rotating member substantially synchronously and non-synchronously with the second rotating member.   
   
   
       2 . The apparatus of  claim 1  wherein one of the first element and the second element includes a hysteresis material. 
   
   
       3 . The apparatus of  claim 1  wherein a magnetic field connects the first element and the second element, the first and the second element being configured to shift wherein the first rotating member and the second rotating member from a synchronous rotation to a non-synchronous rotation when a predetermined torque value is applied by the first rotating member to the second rotating member. 
   
   
       4 . The apparatus of  claim 1  further comprising a modulator configured to control a rotational speed of the second rotating member. 
   
   
       5 . The apparatus of  claim 4  wherein the modulator is configured to reduce a magnetic field connecting the first element and the second element. 
   
   
       6 . The apparatus of  claim 4  wherein the modulator is one of: (i) an eddy current brake connected to the second rotating member, (ii) an oil-pump and nozzle; and (iii) an additional alternator load. 
   
   
       7 . The apparatus of  claim 1  wherein the first element circumferentially surrounds the second element. 
   
   
       8 . The apparatus of  claim 1  wherein the second rotating member is substantially isolated from a drilling fluid. 
   
   
       9 . The apparatus of  claim 1  wherein the first element and the second element are further configured to rotate the second rotating member at a substantially constant speed that is greater than zero when the first rotating member rotates non-synchronously with the second rotating member. 
   
   
       10 . A method for transferring rotary power between a first rotating member and a second rotating member, comprising:
 coupling the first rotating member to the second rotating member;   rotating the first rotating member substantially synchronously with the second rotating member; and   rotating the first rotating member substantially non-synchronously with the second rotating member when the first rotating member exceeds a specified rotary speed.   
   
   
       11 . The method of  claim 10 , further comprising:
 rotating the second rotating member at a substantially constant speed after the first rotating member exceeds the specified rotary speed.   
   
   
       12 . The method of  claim 11  further comprising rotating the first rotating member at a speed greater than the substantially constant speed. 
   
   
       13 . The method of  claim 10 , wherein the coupling is via a magnetic field; and further comprising:
 shifting the first rotating member and the second rotating member from a synchronous rotation to a non-synchronous rotation when a predetermined torque value is applied by the first rotating member to the second rotating member.   
   
   
       14 . The method of  claim 10  further comprising a modulating a rotational speed of the second rotating member. 
   
   
       15 . The method of  claim 14  wherein the modulating reduces a magnetic field connecting the first element with the second element. 
   
   
       16 . The method of  claim 10  further comprising substantially isolating the second rotating member from a drilling fluid. 
   
   
       17 . The method of  claim 10  further comprising rotating the second element at a substantially constant speed that is greater than zero when the first element rotates non-synchronously with the second element. 
   
   
       18 . A system for transferring rotary power, comprising:
 a rotary power generator having a first rotating member;   a consumer having a second rotating member; and   a coupling connecting the first rotating member to the second rotating member, the coupling being configured to rotate the first rotating member substantially synchronously and non-synchronously with the second rotating member.   
   
   
       19 . The system of  claim 18  wherein one of the first rotating member and the second rotating member includes a hysteresis material. 
   
   
       20 . The system of  claim 18  wherein a magnetic field connects the first rotating member and the second rotating member, and wherein the first rotating member and the second rotating member shift from a synchronous rotation to a non-synchronous rotation when a predetermined torque value is applied by the first rotating member to the second rotating member.