Centrifugal-type electric refrigerant compressor having integral orifice-regulated bearing cooling arrangement

1 . A refrigerant E-compressor, comprising:

a housing assembly comprising a compressor housing and a motor housing affixed to the compressor housing;

a compressor wheel affixed to a shaft and contained within the compressor housing;

bearings rotatably supporting the shaft and contained within the motor housing;

a motor stator contained within the motor housing, and a motor rotor affixed about the shaft and contained within the motor housing;

the compressor housing defining a refrigerant inlet leading refrigerant into the compressor wheel, a diffuser, a volute for collecting pressurized refrigerant discharged from the compressor wheel and diffused through the diffuser, and a primary refrigerant flow path extending from the volute to a refrigerant outlet;

a cooling flow path defined in the motor housing for supplying a flow of refrigerant for cooling the motor rotor and the bearings, the cooling flow path including a front branch directed toward a from bearing and a rear branch directed toward a rear bearing;

a plenum formed in the motor housing and arranged between the primary refrigerant flow path and the cooling flow path, the plenum encircling the shaft in a region adjacent the motor rotor; and

a fixed orifice integrally formed within a wall of the primary refrigerant flow path at a location downstream of the volute and upstream of the refrigerant outlet, the fixed orifice fluidly connecting the primary refrigerant flow path to the plenum such that a portion of the refrigerant flowing in the primary refrigerant flow path is bled through the orifice into the plenum and then supplied from the plenum to the cooling flow path for cooling the motor rotor and the bearings; and

wherein the refrigerant is diverted through the fixed orifice without use of external valves or external piping.

2 . The refrigerant E-compressor of claim 1 , wherein the compressor housing comprises a main compressor housing and a separately formed cover that is affixed to the main compressor housing by fasteners, the main compressor housing defining the refrigerant inlet, the volute, and the primary refrigerant flow path.

3 . The refrigerant E-compressor of claim 2 , wherein the fixed orifice is disposed within the main compressor housing.

4 . The refrigerant E-compressor of claim 2 , further comprising a plurality of refrigerant supply passages defined partially in the main compressor housing and partially in the cover, the refrigerant supply passages being connected to the refrigerant inlet.

5 . A method of operating a refrigerant E-compressor comprising: a housing assembly comprising a compressor housing and a motor housing affixed to the compressor housing; a compressor wheel affixed to a shaft and contained within the compressor housing; bearings rotatably supporting the shaft and contained within the motor housing; a motor stator contained within the motor housing, and a motor rotor affixed about the shaft and contained within the motor housing; the compressor housing defining a refrigerant inlet leading refrigerant into the compressor wheel, a diffuser, a volute for collecting pressurized refrigerant discharged from the compressor wheel and diffused through the diffuser, and a primary refrigerant flow path extending from the volute to a refrigerant outlet; and a cooling flow path defined in the motor housing for supplying refrigerant for cooling the motor rotor and the bearings, the cooling flow path including a front branch directed toward a front bearing and a rear branch directed toward a rear bearing; and a plenum formed in the motor housing and arranged between the primary refrigerant flow path and the cooling flow path, the plenum encircling the shaft in a region adjacent the motor rotor; the method comprising the steps of:

bleeding off a portion of the pressurized refrigerant, constituting a bleed portion, from the primary refrigerant flow path at a location downstream of the volute and upstream of the refrigerant outlet;

passing the bleed portion through a fixed orifice integrally formed within a wall of the primary refrigerant flow path, the fixed orifice inducing decreases in pressure and temperature of the bleed portion so as to produce a reduced-temperature bleed portion and discharging the reduced-temperature bleed portion into the plenum; and

feeding the reduced-temperature bleed portion from the plenum into the cooling flow path via the front branch and the rear branch for cooling the motor rotor and the bearings; and

wherein the bleed portion is diverted through the fixed orifice without use of external valves or external piping.

6 . The refrigerant E-compressor according to claim 1 , wherein the plenum is configured to distribute refrigerant from the fixed orifice substantially uniform between the front branch and the rear branch of the cooling flow path.

7 . The refrigerant E-compressor according to claim 1 , wherein the fixed orifice is further configured to regulate flow based upon its diameter and a pressure differential between an inlet to the fixed orifice and outlet from the fixed orifice.

8 . The refrigerant E-compressor according to claim 7 , wherein the fixed orifice is further configured to regulate flow based upon at least one of orifice size, fluid properties or viscosity and pressure conditions.

9 . The method of operating refrigerant E-compressor according to claim 5 , wherein the compressor housing comprises a main compressor housing and a separately formed cover that is affixed to the main compressor housing by fasteners, the main compressor housing defining the refrigerant inlet, the volute, and the primary refrigerant flow path.

10 . The method of operating refrigerant E-compressor according to claim 9 , further comprising the steps of disposing the fixed orifice within the main compressor housing.

11 . The method of operating refrigerant E-compressor according to claim 10 , wherein the refrigerant E-compressor further comprises a plurality of refrigerant supply passages defined partially in the main compressor housing and partially in the cover, the refrigerant supply passages being connected to the refrigerant inlet.

12 . The method of operating refrigerant E-compressor according to claim 11 , further comprising the steps of using the plenum formed in the motor housing to receive a portion of the refrigerant flowing in the primary refrigerant flow path bled off through the fixed orifice and to feed the received portion fed-into the cooling flow path.

13 . The method of operating refrigerant E-compressor according to claim 12 , further comprising the steps of configuring the fixed orifice to regulate flow based upon its diameter and a pressure differential between an inlet to the fixed orifice and outlet from the fixed orifice.

14 . The method of operating refrigerant E-compressor according to claim 13 , further comprising the steps of configuring the fixed orifice to regulate flow based upon at least one of orifice size, fluid properties or viscosity and pressure conditions.

15 . The refrigerant E-compressor according to claim 1 , wherein the fixed orifice is formed in a wall portion of the primary refrigerant flow path upstream of the refrigerant outlet.

16 . The refrigerant E-compressor according to claim 1 , wherein the fixed orifice is defined by a radially extending passage extending from the primary refrigerant flow path into a plenum formed in the housing assembly.

17 . The refrigerant E-compressor according to claim 16 , wherein the plenum is annular and encircles the shaft in a region adjacent the motor rotor.

18 . The refrigerant E-compressor according to claim 1 , wherein a flow area of the front branch and a flow area of the rear branch are selected to provide a predetermined division of the refrigerant flow between the front bearing and the rear bearing.

19 . The refrigerant E-compressor according to claim 1 , wherein the housing assembly is configured such that the fixed orifice, the primary refrigerant flow path, and the cooling flow path are all integrally formed within the walls of the housing assembly.