Apparatus for electrical power and/or data transfer between rotating components in a drill string

Abstract

A downhole tool includes a non-contact, electrical coupling device configured to transmit electrical power and/or data between relatively rotating components. In one embodiment, the coupling device includes at least first and second wound toroidal cores deployed about a shaft. At least one of the wound toroidal cores is rotationally fixed to the shaft, while at least one other is rotationally fixed to a housing in which the shaft is deployed. The shaft forms a portion of a conductive loop that extends through the toroids. A non-contact electrical pathway is advantageously provided for high power electrical transmission and/or high speed data transmission across a gap between first and second rotating members of a downhole assembly.

1 . A downhole tool comprising:
 a shaft deployed in a housing and configured to rotate with respect to the housing; and   a non-contact electrical coupling device configured to transmit an electrical signal between the shaft and the housing, the electrical coupling device including at least first and second axially spaced wound toroidal cores deployed about the shaft, the first wound toroidal core being rotationally coupled with the shaft, the second wound toroidal core being rotationally coupled with the housing.   
   
   
       2 . The downhole tool of  claim 1 , wherein:
 the housing is supported on the shaft by first and second axially spaced bearings, the first and second wound toroidal cores being deployed between the first and second bearings; and   the shaft, the first bearing, the housing, and the second bearing, in combination, forming a conductive loop that passes through a central window of each of the wound toroidal cores.   
   
   
       3 . The downhole tool of  claim 1 , wherein:
 the first wound toroidal core is electrically connected to a first transceiver circuit deployed on the shaft; and   the second wound toroidal core is electrically connected to a second transceiver circuit deployed on the housing.   
   
   
       4 . The downhole tool of  claim 3 , wherein:
 the first transceiver circuit is configured to transmit electrical power and to transmit and receive electronic data; and   the second transceiver circuit is configured to receive electrical power and to transmit and receive electronic data.   
   
   
       5 . The downhole tool of  claim 1 , wherein the first and second wound toroidal cores each comprise a toroidal core having a relative magnetic permeability of at least 10,000 and a Curie Temperature of at least 150 degrees C. 
   
   
       6 . The downhole tool of  claim 1 , wherein the electrical coupling device is configured to simultaneously transmit electrical power and data at mutually exclusive frequencies. 
   
   
       7 . A downhole tool comprising:
 a shaft deployed in a housing, the shaft disposed to rotate with respect to the housing; and   first and second transformers sharing a single-turn conductive loop, at least a first wound toroidal core forming a primary of the first transformer, the first wound toroidal core being deployed about the shaft and rotationally coupled with the shaft, at least a second wound toroidal core forming a secondary of the second transformer, the second wound toroidal core being deployed about the shaft and rotationally coupled with the housing, the second wound toroidal core being axially spaced from the first wound toroidal core, the conductive loop forming both a single-turn secondary of the first transformer and a single-turn primary of the second transformer, the conductive loop comprising a portion of the shaft that extends through central windows of the first and second wound toroidal cores.   
   
   
       8 . The downhole tool of  claim 7 , wherein:
 the housing is supported on the shaft by at least first and second longitudinally spaced bearings, the first and second wound toroidal cores being deployed between the first and second bearings; and   the shaft, the first bearing, the housing and the second bearing, in combination, forming the conductive loop.   
   
   
       9 . The downhole tool of  claim 7 , wherein the primary of the first transformer is electrically connected to a first transceiver circuit deployed on the shaft and the secondary of the second transformer is electrically connected to a second transceiver circuit deployed in the housing. 
   
   
       10 . The downhole tool of  claim 7 , wherein:
 the primary of the first transformer is formed by a first plurality of axially spaced wound toroidal cores electrically connected in parallel;   the secondary of the second transformer is formed by a second plurality of axially spaced wound toroidal cores electrically connected in parallel.   
   
   
       11 . The downhole tool of  claim 10 , wherein each of the first and second pluralities of wound toroidal cores includes from about 5 to about 20 wound toroidal cores. 
   
   
       12 . The downhole tool of  claim 7 , wherein each of the wound toroidal cores comprises a toroidal core having a relative magnetic permeability of at least 10,000 and a Curie Temperature of at least 150 degrees C. 
   
   
       13 . A downhole tool comprising:
 a shaft deployed in a housing and configured to rotate with respect to the housing, the shaft supported in the housing by at least first and second longitudinally spaced bearings;   a non-contact electrical coupling device configured to transmit an electrical signal between the shaft and the housing, the electrical coupling device including first and second longitudinally spaced sets of wound toroidal cores deployed about the shaft and between the first and second bearings, each of the sets including a plurality of longitudinally spaced wound toroidal cores, the first set of wound toroidal cores being rotationally coupled with the shaft, the second set of wound toroidal cores being rotationally coupled with the housing; and   the shaft, the first bearing, the housing, and the second bearing, in combination, forming a conductive loop that passes through a central window of each of the wound toroidal cores.   
   
   
       14 . The downhole tool of  claim 13 , wherein:
 the wound toroidal cores in the first set are electrically connected in parallel and are collectively connected to a first transceiver circuit deployed on the shaft; and   the wound toroidal cores in the second set are electrically connected in parallel and are collectively connected to a second transceiver circuit deployed on the housing.   
   
   
       15 . The downhole tool of  claim 14 , wherein:
 the first transceiver circuit is configured to transmit electrical power and to transmit and receive electronic data; and   the second transceiver circuit is configured to receive electrical power and to transmit and receive electronic data.   
   
   
       16 . The downhole tool of  claim 13 , wherein each of the first and second sets of wound toroidal cores includes from about 5 to about 20 wound toroidal cores electrically connected in parallel. 
   
   
       17 . The downhole tool of  claim 13 , wherein each of the wound toroidal cores comprises a toroidal core having a relative magnetic permeability of at least 10,000 and a Curie Temperature of at least 150 degrees C. 
   
   
       18 . The downhole tool of  claim 13 , wherein:
 the first set of wound toroidal cores forms a primary of a first transformer, the conductive loop forming a secondary of the first transformer; and   the second set of wound toroidal cores forms a secondary of a second transformer, the conductive loop forming a primary of the second transformer.   
   
   
       19 . A rotary steerable tool comprising:
 a shaft deployed in a steering tool housing and configured to rotate with respect to the housing, the shaft supported in the housing by at least first and second longitudinally spaced bearings;   a plurality of blades deployed on the housing, the blades disposed to extend radially outward from the housing and engage a wall of the borehole, said engagement of the blades with the borehole wall operative to eccenter the housing in the borehole;   a non-contact electrical coupling device configured to transmit electrical power from the shaft to the housing, the electrical coupling device including first and second longitudinally spaced sets of wound toroidal cores deployed about the shaft and between the first and second bearings, each of the sets including a plurality of longitudinally spaced wound toroidal cores, the first set of wound toroidal cores being rotationally coupled with the shaft, the second set of wound toroidal cores being rotationally coupled with the housing;   the shaft, the first and second bearings, and the housing in combination forming a conductive loop that passes through a central window of each of the wound toroidal cores.   
   
   
       20 . The rotary steerable tool of  claim 19 , wherein the electrical coupling device is further configured to transmit data back and forth between the shaft and the housing. 
   
   
       21 . The rotary steerable tool of  claim 20 , wherein the electrical coupling device is further configured to simultaneously transmit electrical power and data at mutually exclusive frequencies. 
   
   
       22 . The rotary steerable tool of  claim 20 , wherein the blades are configured to be actuated via electrical power transmitted from the shaft to the housing through the electrical coupling device. 
   
   
       23 . The rotary steerable tool of  claim 19 , wherein
 the first set of wound toroidal cores forms a primary of a first transformer, the conductive loop forming a secondary of the first transformer; and   the second set of wound toroidal cores forms a secondary of a second transformer, the conductive loop forming a primary of the second transformer.   
   
   
       24 . The rotary steerable tool of  claim 19 , wherein each of the first and second sets of wound toroidal cores includes from about 5 to about 20 wound toroidal cores electrically connected in parallel. 
   
   
       25 . The rotary steerable tool of  claim 19 , wherein each of the wound toroidal cores comprises a toroidal core having a relative magnetic permeability of at least 10,000 and a Curie Temperature of at least 150 degrees C.