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. The magnet holders define passages for airflow between the inside top and magnet surface. In this manner, permanent magnets may be installed on the magnet carrying structure and provided with additional cooling via said passages. Further, the holders may be configured to secure the magnets by an interference fit, without using bolts or adhesives, to facilitate both assembly and removal for maintenance and repair.
1. A rotor assembly in a permanent magnet electromechanical machine, comprising:
a rotor having plural magnet mounting surfaces;
a plurality of magnet holders, one at each magnet mounting surface on the rotor, each magnet holder having a top inside surface;
a plurality of magnets, one each retained on said magnet mounting surfaces within a magnet holder, each said magnet having a top surface opposite the magnet mounting surface; and
at least one void defined between said holder top inside surface and said magnet top surface, said at least one void occupying about 90% to 100% of the space between said surfaces.
2. A rotor assembly in a permanent magnet electromechanical machine, comprising:
a rotor having plural magnet mounting surfaces;
a plurality of magnet holders, one at each magnet mounting surface on the rotor, each magnet holder having a top inside surface;
a plurality of magnets, one each retained on said magnet mounting surfaces within a magnet holder, each said magnet having a top surface opposite the magnet mounting surface; and
at least one void defined between said holder top inside surface and said magnet top surface, said at least one void occupying about 90% to 100% of the space between said surfaces,
wherein said holder top inside surface is spaced from the rotor mounting surface by a first predetermined height and said magnet top surface is spaced from said rotor mounting surface by a second predetermined height greater than said first predetermined height of the magnet holder to form an interference fit between the holder top inside surface and the magnet top surface.
3. The rotor assembly of claim 2 , wherein said holder top inside surface and said magnet top surface are configured in combination to form said interference fit as a line contact between said surfaces.
4. The rotor assembly of claim 3 , wherein said at least one void comprises two voids occupying between about 99% and 100% of the space between said surfaces.
5. The rotor assembly of claim 3 , wherein said holder top inside surface and said magnet top surface are configured in combination to form interference fits along plural lines of contact.
6. The rotor assembly of claim 5 , wherein said holder top inside surface is configured to form plural ridges forming said interference fit with said magnet, with plural said voids defined by said ridges.
7. The rotor assembly of claim 2 , wherein said at least one void is occupied by a porous spacing material allowing for air flow therethrough and forming the interference fit between said surfaces.
8. The rotor assembly of claim 2 , wherein said top portion inside surface includes dimples configured to form said interference fit with the magnet top surface.
9. A rotor assembly in a permanent magnet electromechanical machine, comprising:
a rotor having plural magnet mounting surfaces;
a plurality of magnet holders, one at each magnet mounting surface on the rotor, each magnet holder having a top inside surface;
a plurality of magnets, one each retained on said magnet mounting surfaces within a magnet holder, each said magnet having a top surface opposite the magnet mounting surface; and
at least one void defined between said holder top inside surface and said magnet top surface,
wherein said at least one void forms air flow passages for cooling said magnet.
10. The rotor assembly of claim 9 , wherein said at least one void occupies about 90% to 100% of the space between said surfaces.