1. A rotor for use in an electric motor, said rotor comprising:
a plurality of arcuately arranged magnets; and
a plurality of arcuately arranged pole segments,
said pole segments alternating with the magnets, such that each of said magnets is at least in part interposed between adjacent pole segments,
said pole segments being magnetically isolated from each other.
2. The rotor as claimed in claim 1,
said pole segments being spaced apart such that adjacent pole segments do not contact each other.
3. The rotor as claimed in claim 1, further comprising:
retention structure securing the pole segments relative to one another.
4. The rotor as claimed in claim 3,
said retention structure being formed of a magnetically insulative material.
5. The rotor as claimed in claim 4,
said retention structure comprising a body overmolded over at least portions of the pole segments.
6. The rotor as claimed in claim 5,
said body including a hub,
said pole segments interlocking with the hub.
7. The rotor as claimed in claim 6,
said pole segments interlocking with the hub via a dovetail connection.
8. The rotor as claimed in claim 6,
each of said magnets presenting a radially innermost face abutting the hub.
9. The rotor as claimed in claim 8,
said body being overmolded over at least portions of the magnets so as to secure the magnets relative to one another and relative to the pole segments.
10. The rotor as claimed in claim 6,
said rotor further comprising a shaft assembly defining a rotational axis for the rotor,
said shaft assembly being electrically isolated from the pole segments and coupled with the hub.
11. The rotor as claimed in claim 3,
said pole segments defining a plurality of generally axially extending openings filled with a non-magnetic substance.
12. The rotor as claimed in claim 11,
said retention structure further including a plurality of generally axially extending protrusions,
said protrusions extending at least in part through corresponding ones of the openings.
13. The rotor as claimed in claim 1,
each of said pole segments including magnet-positioning structure.
14. The rotor as claimed in claim 13,
said magnet-positioning structure including at least one generally circumferentially extending tab configured to restrict radial displacement of a corresponding one of the magnets.
15. The rotor as claimed in claim 14,
each of said pole segments including\u2014
a pair of arcuately spaced apart, oppositely projecting radially outermost tabs, and
a pair of arcuately spaced apart, oppositely projecting radially innermost tabs.
16. The rotor as claimed in claim 1, further comprising:
a shaft assembly defining a rotational axis for the rotor,
said shaft assembly being electrically isolated from the pole segments.
17. The rotor as claimed in claim 16, further comprising:
retention structure securing the magnets and pole segments relative to one another.
18. The rotor as claimed in claim 17,
said retention structure comprising a body overmolded over at least portions of the magnets and pole segments.
19. The rotor as claimed in claim 18,
said body being overmolded over part of the shaft assembly so as to secure the shaft assembly, magnets, and pole segments to one another.
20. The rotor as claimed in claim 19,
said body being formed of an electrically and magnetically insulative material.
21. The rotor as claimed in claim 19,
said part of the shaft assembly presenting a plurality of teeth.
22. The rotor as claimed in claim 21,
said shaft assembly including a shaft and a coupling element,
said coupling element being interposed between the shaft and the body,
said coupling element presenting the teeth.
23. The rotor as claimed in claim 22,
said coupling element comprising an electrically conductive material powder-coated with an at least substantially electrically insulative material.
24. The rotor as claimed in claim 23,
said coupling element comprising powder-coated aluminum.
25. The rotor as claimed in claim 24,
said shaft assembly further including a key interconnecting the shaft and the coupling element.
26. The rotor as claimed in claim 21,
said shaft assembly consisting essentially of a shaft,
said shaft presenting the teeth.
27. The rotor as claimed in claim 1, further comprising:
retention structure securing the magnets and pole segments to one another,
said retention structure including a body overmolded over at least portions of the magnets and pole segments.
28. The rotor as claimed in claim 27, further comprising:
a shaft assembly defining a rotational axis for the rotor,
said body being fixed relative to the shaft assembly and thereby at least in part securing the shaft assembly, magnets, and pole segments to one another.
29. The rotor as claimed in claim 28,
said body being overmolded over part of the shaft assembly.
30. The rotor as claimed in claim 29,
said body being formed of an electrically and magnetically insulative material.
31. A rotor for use in an electric motor, said rotor comprising:
a shaft assembly rotatable about an axis;
a plurality of magnets arranged arcuately about the shaft assembly; and
a plurality of pole segments arranged arcuately about the shaft assembly,
said pole segments alternating with the magnets, such that each of said magnets is at least in part interposed between adjacent pole segments,
said shaft assembly being electrically isolated from the pole segments.
32. The rotor as claimed in claim 31, further comprising:
a pole segment positioning structure including a hub coupled to the shaft assembly.
33. The rotor as claimed in claim 32,
said shaft assembly including a shaft and a coupling element interconnecting the hub and the shaft.
34. The rotor as claimed in claim 33,
said coupling element comprising an electrically conductive material powder-coated with an at least substantially electrically insulative material.
35. The rotor as claimed in claim 34,
said coupling element comprising powder-coated aluminum.
36. The rotor as claimed in claim 33, further comprising:
said shaft assembly further including a key interconnecting the shaft and the coupling element.
37. The rotor as claimed in claim 33,
said coupling element engaging the hub via a toothed interface.
38. The rotor as claimed in claim 32,
said shaft assembly consisting essentially of a shaft directly engaging the hub.
39. The rotor as claimed in claim 38,
said shaft engaging the hub via a toothed interface.
The claims below are in addition to those above.
All refrences to claim(s) which appear below refer to the numbering after this setence.
What is claimed is:
1. A method of controlling prosthesis positions in a body part where the prosthesis comprises a prosthesis stem and a prosthesis cup, where a selected number of markers is positioned on or by the prosthesis in a known mutual geometry configured to appear on an X-ray, the method comprising:
taking X-rays of the body part including the markers;
loading an X-ray image into an image processing program;
at least one of automatically defining and manually defining a number of artificial lines in the image processing program on the basis of the known mutual geometry of the measurement markers;
comparing the deviation between the positions of the artificial lines and the positions of the markers in the image processing program;
measuring the deviation between the positions of the artificial lines and the positions of the markers in the image processing program;
calculating the respective angles of the prosthesis components by use of a calculating unit in the image processing unit; and
displaying the values of the respective angles.
2. An arrangement at an image processing program for providing information regarding the result of inserting a prosthesis in a hip joint, the prosthesis including components such as a prosthesis stem and a prosthesis cup, wherein the prosthesis stem, prosthesis cup and body parts include markers configured to appear on an X-ray image, and based on information from the image the arrangement can determine position of the components of the prosthesis and body pars, the arrangement comprising:
an X-ray loading device configured to load an X-ray image into the image processing program;
an artificial line providing device configured to provide artificial lines for determining a position of the prosthesis components, wherein said artificial lines are designed to be brought to coincide with image of the markers on the X-ray; and
a calculating unit coupled to the image processing unit configured to calculate the respective angles of the prosthesis components in order to be displayed on a screen of a display unit.
3. The arrangement of claim 2 wherein said markers for the prosthesis stem are balls made from a material that will appear on an X-ray.
4. The arrangement of claim 3 wherein said markers comprise tantalum material arranged in plastic sleeves screwed into the prosthesis stem.
5. The arrangement of claim 2 wherein said markers for the prosthesis stem are formed by a pipe stub.
6. The arrangement of claim 5 wherein said pipe stub comprises one of a metal and a plastic.
7. The arrangement of claim 5 wherein said pipe stub is fixed to the prosthesis by the pipe stub being guided over a neck of the prosthesis.
8. The arrangement of claim 7 wherein said pipe stub is fixed to said neck selected from a group consisting of a set screw and spring loading.
9. The arrangement of claim 5 wherein said pipe stub is fixed to the prosthesis by the pipe stub being guided up over the prosthesis stem.
10. The arrangement of claim 5 wherein said pipe stub includes X-ray proof markers at known positions relative to the geometry of the prosthesis.
11. The arrangement of claim 2 wherein the markers for the prosthesis stem are formed by metal elements positioned in a femoral bone.
12. The arrangement of claim 11 wherein said markers are one of knocked into and drilled into said femoral bone at a known distance from an angle to the prosthesis.
13. The arrangement of claim 2 wherein said markers for the prosthesis cup are formed by means of a standard marker on the prosthesis cup, and at least one metal element marker is placed in a pelvic bone.
14. The arrangement of claim 13 wherein said at least one metal element marker is one of knocked and drilled into said pelvic bone at a known distance from an angle to the prosthesis cup.
15. The arrangement of claim 2 wherein the display unit is configured to display calculated angles and is configured to indicate the existence of one of a retroversion and an anteversion.