Torque coil and method

1. A torque coil comprising:

an inner wire layer helically wound in a constricted state;

an intermediate wire layer helically wound over the inner wire layer in a constricted state;

an outer wire layer helically wound over the intermediate wire layer in a constricted state;

an outer polymer cover surrounding the inner and outer wire layers thereby securing the wire layers within the outer polymer cover, wherein the outer polymer cover secures the inner, intermediate and outer layers without welding, brazing or soldering;

a penetrated section of the torque coil, including the outer wire and outer polymer cover, where the polymer material of the outer polymer cover penetrates between adjacent filars in the outer wire layer to stiffen the coil in the penetrated section; and

a non-penetrated section of the torque coil, including the outer wire and outer polymer cover, where the polymer material of the outer polymer cover does not penetrate between adjacent filars in the outer wire layer allowing flexibility of the coil in the non-penetrated section;

wherein the torque coil has increased relative flexibility in the non-penetrated section and has decreased relative flexibility in the penetrated section.

2. The torque coil of claim 1 further comprising a core of a polymer material within the inner wire layer, such that the inner and outer wire layers are secured between the core and the outer polymer cover.

3. The torque coil of claim 2 , wherein polymer material from the core penetrates between filars in the inner wire layer.

4. The torque coil of claim 1 further comprising:

a tight-wound section wherein at least one of the inner and outer wire layers is tight wound; and

an open-wound section wherein at least one of the inner and outer wire layers is open wound;

wherein the torque coil has increased relative flexibility in the open-wound section and has decreased relative flexibility in the tight-wound section.

5. The torque coil of claim 1 further comprising:

a full-wire layer section wherein both the inner and outer wire layers are within the full-wire layer section; and

a partial-wire layer section wherein the outer wire layer is not within the partial-wire layer section;

wherein the torque coil has increased relative flexibility in the partial-wire layer section and has decreased relative flexibility in the full-wire layer section.

6. The torque coil of claim 1 , wherein a pull wire is attached directly to at least one of the wire layers adjacent a distal end of the torque coil.

7. The torque coil of claim 1 , wherein the coil is configured for high-speed rotation and one-to-one torque.

8. The torque coil of claim 1 , wherein the torque coil comprises an inner lumen having a diameter between 0.008 inches and 0.220 inches, wherein the torque coil has an outer diameter between 0.01 inches and 0.250 inches, and wherein at least one of the inner wire layer and the outer wire layer have a wire diameter between 0.0005 inches and 0.004 inches.

9. A torque coil comprising:

a polymer core;

an inner wire layer helically wound in a constricted state over the polymer core;

an intermediate wire layer helically wound over the inner wire layer in a constricted state;

an outer wire layer helically wound over the intermediate wire layer in a constricted state; and

an outer polymer cover surrounding the inner and outer wire layers thereby securing the wire layers between the polymer core and the outer polymer cover;

a penetrated section of the torque coil, including the outer wire and outer polymer cover, where the polymer material of the outer polymer cover penetrates between adjacent filars in the outer wire layer to stiffen the coil in the penetrated section; and

a non-penetrated section of the torque coil, including the outer wire and outer polymer cover, where the polymer material of the outer polymer cover does not penetrate between adjacent filars in the outer wire layer;

wherein a single filar is used for each of the inner and outer wire layers without being cut; and

wherein the outer polymer cover secures the inner, intermediate and outer layers without welding, brazing or soldering.

10. The torque coil of claim 9 , wherein the torque coil has increased relative flexibility in a flexible section and has decreased relative flexibility in a stiff section.

11. The torque coil of claim 10 , wherein the stiff section of the torque coil comprises one or more of:

a section wherein the polymer material of the outer polymer cover penetrates between adjacent filars in the outer wire layer in the torque coil;

a section wherein the polymer material of the inner polymer core penetrates between adjacent filars in the inner wire layer;

a section wherein at least one of the inner and outer wire layers is tight wound; and

a section wherein both the inner and the outer wire layer is contained within the stiff section.

12. The torque coil of claim 10 , wherein the flexible section of the torque coil comprises one or more of:

a section wherein the polymer material of the outer polymer cover does not penetrate between adjacent filars in the outer wire layer of the torque coil;

a section wherein at least one of the inner and outer wire layers is open wound; and

a section wherein the outer wire layer is not within the flexible section.

13. A method of forming a torque coil comprising:

forming a polymer core;

helically winding an inner wire layer in a constricted state over the polymer core;

helically winding an outer wire layer over the inner wire layer in a constricted state; and

forming an outer polymer cover to surround the inner and outer wire layers thereby securing the wire layers between the polymer core and the outer polymer cover wherein the outer polymer cover secures the inner, intermediate and outer layers without the use of welding, brazing or soldering;

wherein forming the outer polymer cover includes forming a penetrated section of the torque coil such that the polymer material of the outer polymer cover penetrates between adjacent filars in the outer wire layer of the torque coil and includes forming a non-penetrated section of the torque coil such that the polymer material of the outer polymer cover does not penetrate between adjacent filars in the outer wire layer of the torque coil.

14. The method of claim 13 further comprising temporarily securing one of the inner and outer wire layers with a clamp until the outer polymer cover secures the inner and outer wire layers between the core and the outer polymer cover.

15. The method of claim 13 , wherein:

forming the outer polymer cover includes controlling the polymer material of the outer polymer cover such that the polymer material penetrates between adjacent filars in the outer wire layer of the torque coil in a penetrated section; and

forming the outer polymer cover includes controlling the polymer material of the outer polymer cover such that the polymer material does not

penetrate between adjacent filars in the outer wire layer of the torque coil in a non-penetrated section such that the torque coil has increased relative flexibility in the non-penetrated section and has decreased relative flexibility in the penetrated section.

16. The method of claim 13 , wherein:

winding the inner or outer wire layer includes winding a tight-wound section in which at least one of the inner and outer wire layers is tight wound; and

winding the inner or outer wire layer including winding an open-wound section in which at least one of the inner and outer wire layers is open wound, such that the torque coil has increased relative flexibility in the open-wound section and has decreased relative flexibility in the tight-wound section.

17. The method of claim 13 , wherein:

winding the inner and outer wire layer includes winding a full-wire layer section in which both the inner and outer wire layers are within the full-wire layer section; and

winding the inner and outer wire layer includes winding a partial-wire layer section in which the outer wire layer is not within the partial-wire layer section, such that the torque coil has increased relative flexibility in the partial-wire layer section and has decreased relative flexibility in the full-wire layer section.