Method and Apparatus for Permanent Magnet Attachment in an Electromechanical Machine

Abstract

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.

What is claimed is: 
     
         1 . A method for mounting permanent magnets to a magnet carrying structure in an electromechanical machine, comprising:
 providing a magnet holder having a top portion and sides defining at least a first open end, said top portion having an inside surface;   sizing the magnet holder and configuring said top portion inside surface in combination with the magnet to provide an interference fit between the magnet holder and the magnet along facing surfaces thereof when the magnet is retained by the magnet holder on the magnet carrying structure, said interference fit being configured to maintain at least about 90% of the facing surfaces in a spaced apart relationship defining void space there between;   mounting the magnet holder on the magnet carrying structure; and   sliding the magnet into the magnet holder through said first open end to secure the magnet on the magnet carrying structure by said interference fit.   
     
     
         2 . The method of  claim 1 , wherein said top portion inside surface is configured to form said interference fit along a line contact with said magnet. 
     
     
         3 . The method of  claim 1 , wherein said top portion inside surface includes dimples configured to form said interference fit with said magnet. 
     
     
         4 . The method of  claim 1 , wherein said top portion inside surface is configured to form plural ridges forming said interference fit with said magnet. 
     
     
         5 . The method of  claim 1 , further comprising positioning a porous spacer between the magnet holder inside top surface and the magnet. 
     
     
         6 . The method of  claim 1 , wherein said mounting comprises at least one of welding, bolting, or clamping the magnet holder to the magnet carrying structure or mounting the magnet holder to the magnet carrying structure within slots in the magnet carrying structure. 
     
     
         7 . The method of  claim 1 , wherein the magnet carrying structure comprises a rotor. 
     
     
         8 . The method of  claim 7 , wherein the electromechanical machine comprises a wind power unit. 
     
     
         9 . The method of  claim 8 , wherein said wind power unit is mounted on a tower and said sliding and securing steps are performed on said tower. 
     
     
         10 . The method of  claim 9 , 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. 
     
     
         11 . The method of  claim 10 , wherein the loading fixture comprises a plunger to force the magnet into the magnet holder. 
     
     
         12 . The method of  claim 10 , wherein said sliding further comprises aligning the loading fixture with the magnet holder prior to said forcing. 
     
     
         13 . The method of  claim 9 , 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. 
     
     
         14 . The method of  claim 1 , wherein:
 the permanent magnets to be mounted have a height and width;   the magnet holder comprises a body having side walls joined by a closed top to define at least said first open end and an open bottom;   the sides and closed top together define a magnet holder inside height configured and dimensioned in combination with the magnet height and a magnet mounting surface on the magnet carrying structure to define said void space between said closed top and said magnet, said void space occupying about 90% to 100% of the space between said surfaces when the magnet is retained on the magnet mounting surface within said magnet holder.   
     
     
         15 . A magnet holder for securing permanent magnets to a magnet mounting surface on a rotor in an electromechanical machine, wherein the magnets have a height and width, said magnet holder comprising a body having side walls joined by a closed top to define at least a first open end and open bottom, wherein said sides and closed top together define a magnet holder inside height configured and dimensioned in combination with the magnet height and a magnet mounting surface to define at least one void between said closed top and said magnet, said at least one void occupying about 90% to 100% of the space between said surfaces when the magnet is retained on the magnet mounting surface within said magnet holder. 
     
     
         16 . The magnet holder of  claim 15 , further comprising flanges disposed along bottom edges of said sides, said flanges being configured for attachment to the magnet mounting surface. 
     
     
         17 . The magnet holder of  claim 15 , wherein said closed top has an inside surface configured and dimensioned to be spaced from the magnet mounting surface by a predetermined height wherein said predetermined height is less than the height of the magnet to form an interference fit between said closed top inside surface and the magnet. 
     
     
         18 . The magnet holder of  claim 17 , wherein said closed top inside surface and said magnet height configured in combination to form said interference fit as a line contact there between. 
     
     
         19 . The magnet holder of  claim 18 , wherein said at least one void comprises two voids formed on opposite sides of a single line contact, said voids occupying between about 99% and 100% of the space between said surfaces. 
     
     
         20 . The magnet holder of  claim 18 , wherein said closed top and magnet height are configured in combination to form interference fits along plural lines of contact. 
     
     
         21 . The magnet holder of  claim 20 , wherein said closed top is configured to form plural ridges forming said interference fit with said magnet, with plural said voids defined by said ridges. 
     
     
         22 . 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 body in said interference fit.