Induction motor

Abstract

Exemplary embodiments of the present invention relate to an induction motor including a stator having a circular cross-section and an inner passage having a longitudinal axis defining a bore, a solid core steel rotor having a circular cross-section rotatably disposed within the bore of the stator, and an air gap disposed between the rotor and the stator. A copper conductive layer is disposed on the steel rotor to increase the electrical conductance of the rotor. Exemplary embodiments adhere the copper conductive layer to the steel rotor using Hot Isostatic Pressing (HIP). The HIP process encloses the steel rotor and the copper conductive layer in a containment vessel, and adheres the conductive layer to the rotor by applying high temperature and high gas pressure to the outside of the containment vessel.

1 . An induction motor, comprising:
 a stator including an inner passage having a longitudinal axis defining a bore;   a steel rotor rotatably disposed within the bore of the stator, the steel rotor comprising:
 a cylindrical portion extending between a proximal end and a distal end, 
 a proximal end portion disposed at the proximal end and extending orthogonally to the cylindrical portion, and 
 a distal end portion disposed at the distal end and extending orthogonally to the cylindrical portion; and 
   a Hot Isostatic Pressing (HIP) layer of copper integrally adhered to an outer surface of the steel rotor, the HIP layer of copper comprising:
 a cylindrical HIP layer of copper integrally adhered to the cylindrical portion of the rotor, 
 a proximal HIP layer of copper integrally adhered to the proximal end portion of the rotor, and 
 a distal HIP layer of copper integrally adhered to the distal end portion of the rotor; 
   wherein the proximal HIP layer of copper and the distal HIP layer of copper are configured to provide a short circuit flux path across the rotor to engage with complementary poles of the stator.   
     
     
         2 . The induction motor of  claim 1 , wherein the cylindrical HIP layer of copper, the proximal HIP layer of copper and the distal HIP layer of copper form an integral unit. 
     
     
         3 . The induction motor of  claim 1 , wherein the cylindrical HIP layer of copper, the proximal HIP layer of copper and the distal HIP layer of copper have the same thickness. 
     
     
         4 . The induction motor of  claim 1 , wherein the cylindrical HIP layer of copper has a smaller thickness than the proximal HIP layer of copper and the distal HIP layer of copper. 
     
     
         5 . The induction motor of  claim 1 , wherein the HIP layer of copper fits loosely over the steel rotor. 
     
     
         6 . The induction motor of  claim 1 , further comprising:
 an air gap disposed between an outer surface of the rotor and an inner surface of the stator;   a fan shroud; and   a fan system, comprising:
 a set of fan blades affixed to an outer surface of the rotor, and 
 a set of vanes affixed to the fan shroud; 
   wherein the fan blades affixed to the rotor and the vanes affixed to the fan shroud are pneumatically coupled to each other and cooperatively configured to direct cooling air to flow through the air gap axially around the rotor.   
     
     
         7 . The induction motor of  claim 1 , further comprising:
 one or more motor bearings; and   an oil lubrication system for lubricating the one or more motor bearings, the oil lubrication system comprising:
 an oil reservoir for storing a lubricating oil used to lubricate the one or more motor bearings, 
 an oil pump coupled to the oil reservoir for pumping the oil from the oil reservoir to a vertical level of the one or more motor bearings, 
 a first outlet mechanism coupled to the oil pump for returning a first portion of the pumped flow of the oil to the oil reservoir, and 
 a second outlet mechanism coupled to the oil pump for transferring a second portion of the pumped flow of the oil to an oil applicator for transferring the oil onto the motor bearings. 
   
     
     
         8 . The induction motor of  claim 7 , wherein the oil lubrication system further comprises:
 an oil filter having an inlet coupled to the oil reservoir and an outlet coupled to the oil pump for filtering the oil before the oil is pumped by the oil pump; and   an oil-to-ambient heat exchanger for cooling the filtered oil.   
     
     
         9 . The induction motor of  claim 8 , wherein the entire flow of oil pumped by the oil pump is passed through the heat exchanger. 
     
     
         10 . The induction motor of  claim 7 , wherein the first portion of the flow of the oil to the oil reservoir is larger than the second portion of the flow of the oil to the oil applicator. 
     
     
         11 . The induction motor of  claim 7 , wherein the oil applicator comprises:
 an oil slinger configured to receive the oil from the second outlet mechanism and to transfer the oil by a slinging action to a lip of the oil slinger, the oil slinger comprising the lip configured to receive the oil due to the slinging action and to transfer the oil to the motor bearings; and   a piece of felt configured to uniformly distribute the oil slung by the oil slinger.   
     
     
         12 . The induction motor of  claim 7 , wherein the oil lubrication system is configured to transfer the oil to the motor bearings at a peripheral speed of the motor bearings. 
     
     
         13 . The induction motor of  claim 12 , wherein the oil is transferred to the motor bearings at an average speed of 220 feet per second. 
     
     
         14 . An induction motor, comprising:
 a stator including an inner passage having a longitudinal axis defining a bore;   a steel rotor rotatably disposed within the bore of the stator;   an air gap disposed between an outer surface of the rotor and an inner surface of the stator;   a fan shroud; and   a fan system, comprising:
 a set of fan blades affixed to an outer surface of the rotor, and 
 a set of vanes affixed to the fan shroud; 
   wherein the fan blades affixed to the rotor and the vanes affixed to the fan shroud are pneumatically coupled to each other and cooperatively configured to direct cooling air to flow through the air gap axially around the rotor.   
     
     
         15 . The induction motor of  claim 14 , wherein the fan blades and the vanes are cooperatively configured to increase the static pressure of the air in the air gap. 
     
     
         16 . The induction motor of  claim 14 , wherein the fan blades and the vanes are cooperatively configured to increase the speed of the air flowing into the air gap. 
     
     
         17 . The induction motor of  claim 14 , wherein the fan shroud has an inlet curvature configured to assist in introducing the air into the air gap. 
     
     
         18 . The induction motor of  claim 14 , wherein the motor lacks an external cooling mechanism for cooling the stator and the rotor. 
     
     
         19 . An induction motor, comprising:
 a stator including an inner passage having a longitudinal axis defining a bore;   a steel rotor rotatably disposed within the bore of the stator;   a Hot Isostatic Pressing (HIP) layer of copper integrally adhered to an outer surface of the rotor;   an air gap disposed between an outer surface of the HIP layer of copper and an inner surface of the stator;   a fan shroud; and   a fan system, comprising:
 a set of fan blades affixed to an outer surface of the rotor, and 
 a set of vanes affixed to the fan shroud; 
   wherein the fan blades affixed to the rotor and the vanes affixed to the fan shroud are pneumatically coupled to each other and cooperatively configured to direct cooling air to flow through the air gap axially around the rotor.   
     
     
         20 . A method of assembling a rotor for an induction motor, the method comprising:
 providing a steel rotor comprising:
 a cylindrical portion extending between a proximal end and a distal end, 
 a proximal end portion disposed at the proximal end and extending orthogonally to the cylindrical portion, and 
 a distal end portion disposed at the distal end and extending orthogonally to the cylindrical portion; and 
   integrally adhering a cylindrical Hot Isostatic Pressing (HIP) layer of copper to the cylindrical portion of the rotor;   integrally adhering a proximal HIP layer of copper to the proximal end portion of the rotor; and   integrally adhering a distal HIP layer of copper to the distal end portion of the rotor;   wherein the proximal HIP layer of copper and the distal HIP layer of copper are configured to provide a short circuit flux path across the rotor to engage with complementary poles of a stator.