Fluid transfer tube

1. A torque-transfer assembly comprising:

a shaft having an inner surface that defines a bore, the bore defining a shaft axis, wherein the shaft has a first, a second, a third, and a fourth fluid port in fluid communication with the bore, wherein the first fluid port is located a distance along the shaft axis from the second fluid port and the third fluid port is located a distance along the shaft axis from the fourth fluid port; and

a fluid transfer tube having a longitudinal body that defines a tube axis located within the bore and coaxial with the shaft axis, the fluid transfer tube having an outer surface sealingly engaged with the inner surface of the shaft,

wherein the outer surface includes a first indented fluid groove and a second indented fluid groove each parallel to the tube axis, wherein the first indented fluid groove is in fluid communication with the first fluid port and the second fluid port and the second indented fluid groove is in fluid communication with the third fluid port and the fourth fluid port, and

wherein a depth and a width of the first indented fluid groove is different from a depth and a width of the second indented fluid groove.

2. The torque-transfer assembly of claim 1 wherein the first and second indented fluid grooves are each defined by a curved surface indented into the outer surface of the fluid transfer tube.

3. The torque-transfer assembly of claim 2 wherein the curved surface of the first indented fluid groove opposes the inner surface of the shaft to form a sealed fluid transfer passage between the first fluid port and the second fluid port.

4. The torque-transfer assembly of claim 3 wherein a cross-sectional thickness through the fluid transfer tube at the curved surface of the first indented fluid groove is approximately equal to a cross-sectional thickness of the fluid transfer tube at the outer surface.

5. The torque-transfer assembly of claim 1 wherein the shaft includes at least a fifth and a sixth fluid port and wherein the fluid transfer tube includes at least a third indented fluid groove, and wherein the third indented fluid groove is in fluid communication with at least the fifth and the sixth fluid ports.

6. The torque-transfer assembly of claim 5 wherein the third indented fluid groove has a depth and a width substantially the same as the depth and the width of the second indented fluid groove.

7. The torque-transfer assembly of claim 6 wherein the first, second, and third fluid grooves are equally spaced about the circumference of the outer surface of the fluid transfer tube.

8. A torque transfer assembly for communicating fluid between a plurality of fluid ports, the torque transfer assembly comprising:

a shaft having an inner surface that defines a bore, wherein the bore is in fluid communication with the plurality of fluid ports; and

a fluid transfer tube disposed in the bore of the shaft, the fluid transfer tube including:

a cylindrical outer surface engaged with the inner surface of the shaft, the outer surface having a plurality of fluid grooves, wherein each of the plurality of fluid grooves is in fluid communication with at least two of the plurality of fluid ports, and wherein a first of the plurality of fluid grooves has a depth and a width different from a depth and a width of at least one other of the plurality of fluid grooves;

an inner surface that defines a central passage coaxial with the cylindrical outer surface;

a first end that defines a first opening that communicates with the central passage; and

a second end that defines a second opening that communicates with the central passage, and

wherein fluid communicates through the plurality of fluid grooves between the plurality of fluid ports.

9. The torque transfer assembly of claim 8 wherein the plurality of fluid grooves includes three fluid grooves disposed at equal distances apart around the circumference of the fluid transfer tube at the outer surface.

10. The torque transfer assembly of claim 9 wherein a thickness of the fluid transfer tube at the three fluid grooves is substantially the same as a thickness of the fluid transfer tube at the outer surface.

11. The torque transfer assembly of claim 8 wherein a length of each individual groove of the plurality of fluid grooves is at least equal to a distance between the plurality of fluid ports that communicates with the individual groove.

12. The torque transfer assembly of claim 8 wherein each of the plurality of fluid ports is in fluid communication with only one of the plurality of fluid grooves.

13. The torque transfer assembly of claim 8 wherein the fluid transfer tube is under compressive strain from the inner surface of the shaft.

14. The torque transfer assembly of claim 8 wherein the plurality of fluid grooves cooperates with the inner surface of the shaft to communicate fluid between the plurality of fluid ports.

15. The torque transfer assembly of claim 8 wherein the plurality of fluid grooves includes three fluid grooves, and wherein each of the three fluid grooves is in fluid communication with two of the plurality of fluid ports.