Multi-Stage Compressor with Internal Interstage Feed

Abstract

A multi-stage compressor where the refrigerant is transferred from stage to stage internally. The compressor uses a first stage impeller mounted on a first end of motor shaft and a second stage impeller mounted on a second end of the same motor shaft. The motor shaft and both impellers rotate in unison. Refrigerant discharged from the first stage impeller is transferred to the intake of the second state impeller through passages within the compressor itself.

Having described my invention, I claim: 
     
         1 . A compressor for pressurizing a working fluid, comprising:
 (a) a motor shaft having a first end, a second end, and a central axis;   (b) a motor driving said motor shaft;   (c) a first stage impeller attached to said first end of said motor shaft;   (d) a second stage impeller attached to said second end of said motor shaft;   (e) said second stage impeller in operation creating a second tractive force that opposes a first tractive force created by said first stage impeller;   (f) a housing containing said motor shaft, said first stage impeller, said second stage impeller, and said motor;   (g) said first stage impeller taking in said working fluid proximate said central axis and discharging an interstage flow;   (h) an internal passage carrying said interstage flow within said housing;   (i) said internal passage including a plurality of second stage transfer passages, with each of said second stage transfer passages receiving a portion of said interstage flow, bending said interstage flow through approximately 180 degrees, and directing said interstage flow into said second stage impeller;   (j) said second stage impeller taking in said interstage flow proximate said central axis and discharging a second stage exit flow;   (k) a plurality of outlet transfer passages, with each of said outlet transfer passages receiving a portion of said second stage exit flow and carrying it to an outlet; and   (l) said plurality of second stage transfer passages and said outlet transfer passages passing by each other in proximity to said second stage impeller, with said second stage transfer passages and said outlet transfer passages keeping said interstage flow separate from said second stage outlet flow.   
     
     
         2 . The compressor for pressurizing a working fluid as recited in  claim 1 , wherein said outlet transfer passages join to form a single outlet. 
     
     
         3 . The compressor for pressurizing a working fluid as recited in  claim 2 , wherein said single outlet lies proximate said central axis. 
     
     
         4 . The compressor for a working fluid as recited in  claim 1 , wherein each of said outlet transfer passages flows to an individual outlet. 
     
     
         5 . The compressor for a working fluid as recited in  claim 4 , wherein said individual outlets lie outward from said central axis. 
     
     
         6 . The compressor for a working fluid as recited in  claim 1 , wherein a portion of said interstage flow is directed around said motor in order to cool said motor. 
     
     
         7 . The compressor for a working fluid as recited in  claim 1 , further comprising an economizer inlet positioned to direct return flow from an economizer around said motor in order to cool said motor. 
     
     
         8 . A compressor for pressurizing a working fluid, comprising:
 (a) a motor shaft having a first end, a second end, and a central axis;   (b) a motor driving said motor shaft;   (c) a first stage impeller attached to said first end of said motor shaft;   (d) a second stage impeller attached to said second end of said motor shaft;   (e) said second stage impeller in operation creating a second tractive force that opposes a first tractive force created by said first stage impeller;   (f) a housing containing said motor shaft, said first stage impeller, said second stage impeller, and said motor;   (g) said first stage impeller taking in said working fluid proximate said central axis and discharging an interstage flow;   (h) an internal passage carrying said interstage flow within said housing;   (i) said internal passage bending said interstage flow through approximately 180 degrees, and directing said interstage flow into said second stage impeller;   (j) said second stage impeller taking in said interstage flow proximate said central axis and discharging a second stage exit flow;   (k) a plurality of outlet transfer passages, with each of said outlet transfer passages receiving a portion of said second stage exit flow and carrying it to an outlet; and   (l) said plurality of second stage transfer passages and said internal passage passing by each other in proximity to said second stage impeller, with said internal passage and said outlet transfer passages keeping said interstage flow separate from said second stage outlet flow.   
     
     
         9 . The compressor for pressurizing a working fluid as recited in  claim 8 , wherein said outlet transfer passages join to form a single outlet. 
     
     
         10 . The compressor for pressurizing a working fluid as recited in  claim 9 , wherein said single outlet lies proximate said central axis. 
     
     
         11 . The compressor for a working fluid as recited in  claim 8 , wherein each of said outlet transfer passages flows to an individual outlet. 
     
     
         12 . The compressor for a working fluid as recited in  claim 8 , wherein said individual outlets lie outward from said central axis. 
     
     
         13 . The compressor for a working fluid as recited in  claim 8 , wherein a portion of said interstage flow is directed around said motor in order to cool said motor. 
     
     
         14 . The compressor for a working fluid as recited in  claim 8 , further comprising an economizer inlet positioned to direct return flow from an economizer around said motor in order to cool said motor. 
     
     
         15 . A compressor for pressurizing a working fluid, comprising:
 (a) a motor shaft having a first end, a second end, and a central axis;   (b) a motor driving said motor shaft;   (c) a first stage impeller attached to said first end of said motor shaft;   (d) a second stage impeller attached to said second end of said motor shaft;   (e) said second stage impeller in operation creating a second tractive force that opposes a first tractive force created by said first stage impeller;   (f) a housing containing said motor shaft, said first stage impeller, said second stage impeller, and said motor;   (g) said first stage impeller taking in said working fluid proximate said central axis and discharging an interstage flow;   (h) an internal passage carrying said interstage flow within said housing;   (i) a plurality of second stage transfer passages, with each of said second stage transfer passages receiving a portion of said interstage flow, bending said interstage flow through approximately 180 degrees, and directing said interstage flow into said second stage impeller;   (j) said second stage impeller taking in said interstage flow proximate said central axis and discharging a second stage exit flow;   (k) an outlet transfer passage carrying said second stage exit flow to an outlet; and   (l) said plurality of second stage transfer passages and said outlet transfer passage passing by each other in proximity to said second stage impeller, with said second stage transfer passages and said outlet transfer passage keeping said interstage flow separate from said second stage outlet flow.   
     
     
         16 . The compressor for pressurizing a working fluid as recited in  claim 1 , wherein said outlet transfer passage carries said second stage exit flow to a single outlet. 
     
     
         17 . The compressor for pressurizing a working fluid as recited in  claim 16 , wherein said single outlet lies proximate said central axis. 
     
     
         18 . The compressor for a working fluid as recited in  claim 15 , wherein a portion of said interstage flow is directed around said motor in order to cool said motor. 
     
     
         19 . The compressor for a working fluid as recited in  claim 16 , wherein a portion of said interstage flow is directed around said motor in order to cool said motor. 
     
     
         20 . The compressor for a working fluid as recited in  claim 15 , further comprising an economizer inlet positioned to direct return flow from an economizer around said motor in order to cool said motor.