Method and apparatus for permanent magnet attachment in an electromechanical machine
View Patent ↗An apparatus and method for the installation and removal of permanent magnets in a permanent magnet electromechanical machine, for example a wind turbine power unit generator. A magnet holder is mounted on a magnet carrying structure such as a rotor. Permanent magnets may be inserted into and removed from the magnet holder after the electromechanical machine is assembled. In this manner, permanent magnets may be installed on the magnet carrying structure by an interference fit, without using bolts or adhesives, to facilitate both assembly and removal for maintenance and repair.
1. A method for mounting permanent magnets in an electromechanical machine, comprising:
mounting a magnet holder onto a magnet carrying structure, the magnet holder having a top portion and sides with an open first end;
sizing the magnet holder in combination with the magnet to provide an interference fit between the magnet holder, a magnet, and the magnet carrying structure, with line-to-line contact between the magnet holder top portion and the magnet;
sliding the magnet into the holder through the first open end; and
securing the magnet with said holder by said interference fit between the magnet carrying structure, the magnet, and the magnet holder.
2. The method of claim 1 , wherein said mounting comprises welding the magnet holder to the magnet carrying structure.
3. The method of claim 1 , wherein said mounting comprises bolting the magnet holder to the magnet carrying structure.
4. The method of claim 1 , wherein said mounting comprises clamping the magnet holder to the magnet carrying structure.
5. The method of claim 1 , wherein said mounting comprises mounting the magnet holder to the magnet carrying structure within slots in the magnet carrying structure.
6. The method of claim 1 , wherein the magnet carrying structure comprises a rotor.
7. The method of claim 6 , wherein the electromechanical machine comprises a wind power unit.
8. The method of claim 7 , wherein said wind power unit is mounted on a tower and said sliding and securing steps are performed on said tower.
9. The method of claim 1 , wherein said sliding comprises securing a loading fixture to the rotor, placing a magnet into the loading fixture, and forcing the magnet into the magnet holder from said loading fixture.
10. The method of claim 9 , wherein the loading fixture comprises a screw-driven plunger to force the magnet into the magnet holder.
11. The method of claim 9 , wherein the loading fixture comprises a hydraulically driven plunger to force the magnet into the magnet holder.
12. The method of claim 9 , wherein the loading fixture comprises a pneumatically driven plunger to force the magnet into the magnet holder.
13. The method of claim 9 , wherein the loading fixture comprises an electrically driven plunger to force the magnet into the magnet holder.
14. The method of claim 9 , wherein said sliding further comprises aligning the loading fixture with the magnet holder prior to said forcing.
15. The method of claim 1 , wherein the magnets are provided in magnet sections and said sliding comprises advancing plural magnet sections into the magnet holder.
16. The method of claim 1 , wherein the magnet holder has an open second end, said method further comprising removing the magnets through the magnet holder open second end for maintenance or replacement.
17. A magnet holder for securing permanent magnets to a magnet mounting surface in an electromechanical machine, wherein the magnets have a height, width and length, said magnet holder comprising:
a body having side walls joined by a closed top to define at least a first open end, and an open bottom,
said top having longitudinal facets formed therein along each side wall, and
said side walls and facets defining a magnet holder inside height configured and dimensioned in combination with the magnet height and magnet mounting surface such that said closed top engages a magnet with an interference fit along line-to-line contact when secured to an electromechanical machine.
18. The magnet holder of claim 17 , further comprising flanges disposed along bottom edges of said sides, said flanges being configured for attachment to the magnet mounting surface.
19. The magnet holder of claim 17 , wherein the magnet holder inside height is configured and dimensioned so as to not exceed an elastic deformation limit of the magnet holder in said interference fit.
20. The magnet holder of claim 17 , wherein said body is made of a non-magnetic material.
21. A rotor assembly in an electromechanical machine, comprising:
a rotor having plural magnet mounting surfaces;
a plurality of magnet holders, one disposed at each magnet mounting surface on the rotor, each magnet holder having an inside top surface spaced from the rotor mounting surface by a predetermined height; and
a plurality of magnets, one each disposed on a magnet mounting surface within a magnet holder wherein each said magnet has a predetermined height greater than said predetermined height of the magnet holder to form an interference fit along a line-to-line contact with the magnet holder inside top surface when disposed therein.
22. The rotor assembly of claim 21 , wherein said magnet holder has a closed top used to contain the magnet, an open bottom providing access to the mounting surface during insertion and removal of magnets, at least one open end for insertion and removal of magnets, and edge flanges parallel to the closed top and open bottom to enable attachment of the holder to the rotor.
23. The rotor assembly of claim 21 , wherein adjacent magnet holders are secured to the rotor by clamps.
24. The rotor assembly of claim 21 , wherein the magnet holders are secured to the rotor by welding.
25. A rotor assembly in an electromechanical machine, comprising:
a rotor having plural magnet mounting surfaces;
a plurality of magnet holders, one disposed at each magnet mounting surface on the rotor, each magnet holder having an inside top surface spaced above the rotor mounting surface by a predetermined height; and
a plurality of magnets, one each disposed on a magnet mounting surface within a magnet holder wherein each said magnet has a predetermined height greater than said predetermined height of the magnet holder to form an interference fit with the magnet holder along a single line of contact when the magnet is disposed therein;
wherein each said magnet holder comprises a first side and an opposite second side, each said side having an inwardly directed flange, said flanges defining said inside top surface.
26. The rotor assembly of claim 25 , wherein said inwardly directed flanges for each said side of a magnet holder terminate in a spaced apart relationship.
27. The rotor assembly of claim 21 , wherein the electromechanical machine is a wind power unit.
28. A method of assembling components of an electromechanical machine, comprising:
a) assembling a generator/motor unit, including steps of
providing a stator,
attaching a magnet holder to a wind-power unit rotor, and
rotationally attaching the rotor and the stator; and
b) inserting a magnet into the magnet holder and forming line-to-line contact between the magnet and magnet holder to secure the magnet by interference fit with the magnet holder after said assembling.
29. The method of claim 28 , wherein the electromechanical machine is a wind power unit.
30. The method of claim 28 , wherein the wind power unit is disposed on a tower and said inserting step (b) is performed on the wind power unit on the tower.
31. The magnet holder of claim 17 , wherein said interference fit comprises line-to-line contact between said closed top and the magnet.
32. The magnet holder of claim 31 , wherein said longitudinal facets facilitate flexing of the magnet holder to maintain said interference fit.
33. The magnet holder of claim 31 , further comprising in combination a permanent magnet, said permanent magnet having a rounded top and being sized in combination with said magnet holder to provide said interference fit with said line-to-line contact.
34. The rotor assembly of claim 21 , wherein said magnet holders each comprise a body having side walls joined by a closed top with longitudinal facets formed in said top along each side wall.
35. The method of claim 1 , wherein said magnet holder comprises a body having side walls joined by a closed top with longitudinal facets formed in said top along each side wall.
36. The method of claim 28 , wherein said magnet holder comprises a body having side walls joined by a closed top with longitudinal facets formed in said top along each side wall.
37. The method of claim 9 , wherein said turbine comprises a wind power unit mounted on a tower and said sliding and securing steps are performed on said tower.
38. The method of claim 1 , wherein said line-to-line contact is formed between the magnet holder and the magnet in a central part of the top portion of the magnet holder.
39. The magnet holder of claim 17 , wherein said magnet holder is configured and dimensioned to engage the magnet with said line-to-line contact in a central part of said closed top.
40. The rotor assembly of claim 21 , wherein said line-to-line contact between the magnet and the magnet holder inside top surface is only in a central part of said inside top surface.
41. The method of claim 28 , wherein said line-to-line contact is formed between the magnet holder and the magnet in a central part of the top portion of the magnet holder.