Electric Motor Rotor

Abstract

A rotor of an electric machine is disclosed that resists expansion of the rotor components even at high rotational speed. The rotor includes first and second pluralities of laminations having slots to accept rotor bars. A support disk, also having slots, is placed between the laminations. The support disk, into which the rotor bars are slid, restrains the rotor bars from bending outwardly at high rotational speeds of the rotor. The rotor bars are further restrained at the ends by end rings, which have apertures into which ends of the rotor bars are placed. In some embodiments, containment rings are placed over axial extension of the end rings to prevent outward bowing at high speeds. In some embodiments, the rotor includes a stiffener sleeve to provide additional resistance to expansion during high rotational speeds.

1 . A method to manufacture a rotor of an electric machine, the method comprising:
 arranging two sets of rotor laminations on either side of a support disk;   inserting rotor bars into slots defined in the rotor laminations and the support disk; and   installing end rings at ends of the rotor bars with apertures defined in the end rings engaging with ends of the rotor bars.   
     
     
         2 . The method of  claim 1  wherein:
 the inserting rotor bars comprises injection molding the rotor bars into the slots; and 
 the slots in the rotor laminations and the central support disk are aligned prior to the injection molding. 
 
     
     
         3 . The method of  claim 1 , further comprising:
 clamping the end rings axially with the rotor laminations and the support disk clamped therebetween; and   welding tips of the rotor bars to the end rings.   
     
     
         4 . The method of  claim 1  wherein the rotor laminations, the rotor bars, the end rings, and the support disk comprise a rotor assembly, the method further comprising:
 providing a heat sink in contact with the rotor assembly during the welding. 
 
     
     
         5 . The method of  claim 3  wherein the rotor laminations, the rotor bars, the end rings, and the support disk comprise a rotor assembly, the method further comprising:
 machining outer surfaces of the rotor assembly to improve the balance of the rotor assembly during rotation of the rotor assembly. 
 
     
     
         6 . The method of  claim 3  wherein the rotor laminations, the rotor bars, the end rings, and the support disk comprise a rotor assembly, the method further comprising: press fitting the rotor assembly onto a stiffener sleeve. 
     
     
         7 . The method of  claim 6  further comprising: press fitting the stiffener sleeve on a rotor shaft. 
     
     
         8 . The method of  claim 3  wherein the rotor laminations, the rotor bars, the end rings, and the support disk comprise a rotor assembly, the method further comprising: press fitting the rotor assembly onto a rotor shaft. 
     
     
         9 . A rotor of an electric machine, comprising:
 a first plurality of laminations arranged axially, the first plurality of laminations defining a plurality of slots;   a second plurality of laminations arranged axially, the second plurality of laminations defining a plurality of slots; and   a support disk defining a plurality of slots wherein the support disk is located between the first and second plurality of lamination with slots of the first and second pluralities of lamination and slots of the support disk being aligned.   
     
     
         10 . The rotor of  claim 9 , further comprising: rotor bars slid into the aligned slots. 
     
     
         11 . The rotor of  claim 10 , further comprising: first and second end rings defining apertures with first ends of the rotor bars engaging with the apertures of the first end ring and second ends of the rotor bars engaging with the apertures of the second end ring. 
     
     
         12 . The rotor of  claim 11  wherein the first ends of the rotor bars are welded to the first end disk and the second ends of the rotor bars are welded to the second end disk. 
     
     
         13 . The rotor of  claim 12 , further comprising:
 a stiffener sleeve wherein the welded assembly is fit onto the stiffener sleeve; and   a rotor shaft wherein the stiffener sleeve is fit onto the rotor shaft.   
     
     
         14 . The rotor of  claim 13  wherein the stiffener sleeve comprises a protuberance extending radially outwardly from the stiffener sleeve wherein the protuberance provides a shoulder for a removal tool. 
     
     
         15 . The rotor of  claim 12 , further comprising: a rotor shaft wherein the welded assembly is fit onto the rotor shaft. 
     
     
         16 . A rotor of an electric machine, comprising:
 a first plurality of laminations arranged axially, the first plurality of laminations defining a plurality of slots;   rotor bars provided within the slots;   first and second end rings defining apertures with first ends of the rotor bars engaging with the apertures of the first end ring and second ends of the rotor bars engaging with the apertures of the second end ring wherein the first ends of the rotor bars are welded to the first end ring and the second ends of the rotor bars are welded to the second end ring.   
     
     
         17 . The rotor of  claim 16 , further comprising:
 a second plurality of laminations arranged axially, the second plurality of laminations defining a plurality of slots; and   a support disk defining a plurality of slots wherein the support disk is located between the first and second plurality of laminations with slots of the first and second pluralities of laminations and slots of the support disk being aligned; and the rotor bars extend through the slots in the support disk and the slots in the second plurality of laminations.   
     
     
         18 . The rotor of  claim 16 , further comprising:
 a stiffener sleeve wherein the welded assembly is fit onto the stiffener sleeve; and   a rotor shaft wherein the stiffener sleeve is fit onto the rotor shaft.   
     
     
         19 . The rotor of  claim 16  wherein the first end ring has a first extension extending axially; the first extension extends away from the first plurality of laminations; the second end ring has a second extension extending axially; and the second extension extends away from the first plurality of laminations, the rotor further comprising:
 a first containment ring placed over the first extension; and 
 a second containment ring placed over the second extension. 
 
     
     
         20 . The rotor of  claim 17  wherein the rotor bars, the support disk, and the first and second end disks are injection molded onto the first and second pluralities of laminations. 
     
     
         21 . A method to manufacture a rotor of an electric machine, the method comprising:
 arranging two sets of rotor laminations with slots defined in the laminations aligned;   placing the rotor laminations into a mold surrounding a die;   securing the laminations in place; and   injecting molten alloy into the die.   
     
     
         22 . The method of  claim 21  wherein the alloy and the rotor laminations form a rotor assembly, the method further comprising:
 ejecting the rotor assembly from the mold; and 
 removing the die from the rotor assembly. 
 
     
     
         23 . The method of  claim 22 , further comprising: fitting first and second containment rings over extensions that extend axially from ends of the rotor assembly. 
     
     
         24 . The method of  claim 22 , further comprising: press fitting the rotor assembly onto a sleeve stiffener. 
     
     
         25 . The method of  claim 24 , further comprising: press fitting the sleeve stiffener onto a rotor shaft.