Noise reduction motor design and method

Abstract

An electric motor design and method useful to reduce noise/vibration generated by a rotor/shaft assembly is provided whereby the motor has a stator which has an axial length and a rotor which has an axial length less than the axial length of the stator such that when the rotor rotates within the motor, the rotor is axially fixed by a stator field.

1. A method of reducing noise/vibration caused by oscillation of an electric motor rotor including steps of:
 providing a stator having an axial length;  
 providing a rotor having an axial length which is about between ⅛ to 2/8 inches shorter than said axial length of said stator;  
 applying an electric current to said electric motor which generates a magnetic flux within said electric motor to cause said rotor to rotate with a stator field.  
 
     
     
       2. An electric motor having reduced noise and vibration, comprising:
   a stator formed from a plurality of stacked stator laminations, wherein the stack of stator laminations has a first axial length;        a rotating shaft extending through the stack of stator laminations along the axis of the stator; and        a rotor attached to the shaft and centered axially with the first axial length of stator, the rotor being formed from a plurality of stacked rotor laminations, wherein the stack of rotor laminations has a second axial length,        wherein the first axial length of the stack of stator laminations is greater than the second axial length of the stack of rotor laminations such that during operation of the motor, a magnetic flux generated by the stator limits the axial movement of the shaft and rotor to reduce the noise and vibration of the motor.      
     
     
       3. The motor of  claim 2  wherein the stator laminations and the rotor laminations have the same thickness.  
     
     
       4. The motor of  claim 2  wherein the stack of stator laminations includes a larger number of stator laminations than the number of rotor laminations in the stack of rotor laminations.