Methods for coupling permanent magnets to a rotor body of an electric motor

Abstract

A permanent magnet for a permanent magnet electric motor is bonded to a rotor. A hole having a chamfered outer edge is formed in the permanent magnet. A corresponding mounting hole is formed in the body of the rotor. A bolt is threaded through the hole in the permanent magnet and threaded into the mounting hole of the rotor. An O-ring is positioned between the head of the bolt and the permanent magnet. The O-ring may be made of an elastomeric material which may prevent cracking of the permanent magnet as components of the electric motor expand and contract with fluctuations in temperature. A magnet may be held to a rotor by a dovetail or may include a flange to be held to the rotor by a retaining ring.

1 - 11 . (canceled) 
     
     
         12 . A rotor for a permanent magnet electric motor comprising:
 a rotor body, the rotor body being generally cylindrical in shape, the rotor body having an outer surface, the rotor body including a mounting hole, the mounting hole positioned to couple to a threaded connector;   a permanent magnet, the permanent magnet being generally in the form of an annular section, the concave surface of the permanent magnet having a diameter generally equal to the outer diameter of the rotor body, the permanent magnet having a hole formed therein positioned to receive the threaded connector, the hole having a countersink formed therein at the convex surface of the permanent magnet; and   an elastomeric body positioned within the countersink between the threaded connector and the permanent magnet.   
     
     
         13 . A method comprising:
 providing a rotor body, the rotor body being generally cylindrical in shape, the rotor body having an outer surface, the outer surface of the rotor body having at least one dovetail channel;   providing a permanent magnet, the permanent magnet being generally in the form of an annular section, the concave surface of the permanent magnet having a diameter generally equal to the outer diameter of the rotor body, the permanent magnet including at least one dovetail adapted to fit into the dovetail channel; and   sliding the permanent magnet on the outer surface of the rotor body so that the dovetail couples to the dovetail channel.   
     
     
         14 . A method comprising:
 providing a rotor body, the rotor body being generally cylindrical in shape, the rotor body having an outer surface;   providing a retaining ring;   providing a permanent magnet, the permanent magnet being generally in the form of an annular section, the concave surface of the permanent magnet having a diameter generally equal to the outer diameter of the rotor body, the permanent magnet having at least one flange extending from an end of the permanent magnet, the flange adapted to allow the retaining ring to hold the permanent magnet to the rotor body by compressing the flange to the rotor body;   positioning the permanent magnet on the outer surface of the rotor body; and   positioning the retaining ring about the rotor body and permanent magnet such that the retaining ring is generally aligned with the flange.   
     
     
         15 . The method of  claim 13 , wherein the permanent magnet is formed by sintering of a permanent magnetic material. 
     
     
         16 . The method of  claim 15 , wherein the dovetail of the permanent magnet is formed during the sintering process. 
     
     
         17 . The method of  claim 13 , further comprising forming the dovetail channel by removing material from the rotor body. 
     
     
         18 . The method of  claim 13 , wherein the dovetail channel is formed separately from the rotor body, and wherein the method further comprises coupling the dovetail channel to the rotor body. 
     
     
         19 . The method of  claim 18 , wherein the dovetail channel is coupled to the rotor body by a threaded coupler. 
     
     
         20 . The method of  claim 14 , wherein the permanent magnet is formed by sintering of a permanent magnetic material. 
     
     
         21 . The method of  claim 15 , wherein the flange of the permanent magnet is formed during the sintering process. 
     
     
         22 . The method of  claim 14 , wherein the retaining ring is a split ring. 
     
     
         23 . The method of  claim 22 , wherein a first end of the split ring retaining ring is coupled to the rotor body. 
     
     
         24 . The method of  claim 23 , wherein a first end of the split ring retaining ring is coupled to a second end of the split ring retaining ring.