Coil Design for Improved Rotational Performance

Abstract

A coil for transmitting torque comprises a wire having a longitudinal axis and first and second longitudinal edges extending along the longitudinal axis, wherein the first longitudinal edge is formed with a first pattern and the second longitudinal edge is formed with a second pattern complementary to the first pattern, the first and second patterns being configured to interlock with one another when the wire is wound into a helical shape.

1 . A coil for transmitting torque, comprising:
 a wire having a longitudinal axis and first and second longitudinal edges extending along the longitudinal axis, wherein the first longitudinal edge is formed with a first pattern and the second longitudinal edge is formed with a second pattern complementary to the first pattern, the first and second patterns being configured to interlock with one another when the wire is wound into a helical shape.   
     
     
         2 . The coil according to  claim 1 , wherein surface features on the first longitudinal edge of the wire are separated from corresponding features with which they are to mate on the second longitudinal edge by a distance along a path around which the coil is wound corresponding to a complete revolution of the coil about the longitudinal axis of the coil. 
     
     
         3 . The coil according to  claim 2 , wherein the first pattern is a first wave pattern and the second pattern is a second complementary wave pattern interlocking with the first wave pattern when the wire is wound into the coil. 
     
     
         4 . The coil according to  claim 3 , wherein the first wave pattern includes a plurality of first projections and first indentations, the first projections being sized to be received within corresponding second indentations in the second wave pattern and wherein the first indentations are sized to receive corresponding second projections of the second wave pattern. 
     
     
         5 . The coil according to  claim 2 , wherein the first pattern includes a plurality of trapezoidal protrusions and wherein the second pattern includes a pattern of complementarily sized substantially rectangular recesses. 
     
     
         6 . The coil according to  claim 5 , wherein the trapezoidal protrusions and substantially rectangular recesses comprise smoothed edges. 
     
     
         7 . The coil according to  claim 2 , wherein the wire is a flat strip, a width of the flat strip being substantially uniform along the length of the coil. 
     
     
         8 . The coil according to  claim 1 , wherein turns of the wound wire form a closed pitch coil. 
     
     
         9 . The coil according to  claim 1 , wherein the coil is wound with a preload greater than zero. 
     
     
         10 . The coil according to  claim 2 , wherein the first and second patterns are formed on the wire prior to winding the wire into the coil. 
     
     
         11 . The coil according to  claim 9 , wherein the first and second patterns are formed on the flat strip via one of progressive stamping and continuous knurling. 
     
     
         12 . The coil according to  claim 1 , wherein adjacent turns of the coil are wound in close proximity with one another to ensure mechanical interaction therebetween. 
     
     
         13 . A coil for transmitting torque, comprising:
 a wire having a longitudinal axis and first and second longitudinal planar surfaces extending along the longitudinal axis, wherein the first planar surface is formed with a first pattern and the second planar surface is formed with a second pattern complementary to the first pattern, the first and second patterns being configured to interlock with one another when the wire is wound into a helical shape.   
     
     
         14 . The coil according to  claim 13 , wherein surface features on the first planar surface of the wire are separated from corresponding features with which they are to mate on the second planar surface by a distance along a path around which the coil is wound corresponding to a complete revolution of the coil about the longitudinal axis of the coil. 
     
     
         15 . The coil according to  claim 13 , wherein first and second adjacent turns of the coil axially overlap over one another and wherein the first turn includes a projection slidably received in an aperture formed on the second turn to prevent rotation of the first and second turns relative to one another about a longitudinal axis of the elongated body. 
     
     
         16 . The coil according to  claim 15 , wherein portions of the turns overlapping adjacent turns include one of knurled and roughed edges to increase a mechanical interaction therebetween. 
     
     
         17 . The coil according to  claim 14 , wherein a first side of the flat strip includes a plurality of tabs and a second side of the flat strip includes a plurality of apertures spaced along the wire by a distance selected so that, when wound into a coil, each of the tabs is slidably received within a corresponding one of the apertures. 
     
     
         18 . The coil according to  claim 17 , wherein a difference between a length of the apertures and a length of the tabs is selected to achieve a desired minimum bending radius of the coil. 
     
     
         19 . The coil according to  claim 17 , wherein the wire is wound so that the tabs extend radially outward from a longitudinal axis of the elongated body and wherein the wire is wound into a coil including substantially conical individual turns with the tabs formed on reduced diameter portions of the turns received within enlarged diameter portions of adjacent turns so that each tab extends radially outward into a corresponding aperture. 
     
     
         20 . The coil according to  claim 13 , further comprising a second wound element interspersed with the first wound element within the coil. 
     
     
         21 . The coil according to  claim 20 , wherein adjacent surfaces of the first and second wound elements mechanically engage one another to prevent relative rotation between adjacent turns of the coil. 
     
     
         22 . A medical device, comprising:
 a coil configured to transmit torque comprising a wire having a longitudinal axis and first and second longitudinal edges extending along the longitudinal axis, wherein the first longitudinal edge is formed with a first pattern and the second longitudinal edge is formed with a second pattern complementary to the first pattern, the first and second patterns being configured to interlock with one another when the wire is wound into a helical shape, the coil comprising an elongated body defining an internal lumen configured to permit insertion of a medical instrument therethrough.   
     
     
         23 . A medical device for forming a flat strip, comprising:
 a first forming wheel comprising a first radially abutting portion; and   a second forming wheel comprising a first radial recess portion configured for engagement with the first radially abutting portion so that, when the first and second forming wheels are brought into an engaged configuration, a clearance is provided between, the clearance permitting insertion of the flat strip therethrough with a substantial friction fit to cause a desired forming thereof.   
     
     
         24 . The medical device of  claim 23 , further comprising:
 a housing configured to retain the first forming wheel and the second forming wheel in the engaged configuration relative to one another.   
     
     
         25 . The medical device of  claim 23 , wherein the first and second forming wheels are selectively positionable to change a size of the clearance to accommodate a predetermined size of the flat strip.