Motor cooling method for a compressor

Patent metadata

Field	Value
Publication number	US-9395111-B2
Application number	US-201314423472-A
Country	US
Kind code	B2
Filing date	Oct 23, 2013
Priority date	Nov 28, 2012
Publication date	Jul 19, 2016
Grant date	Jul 19, 2016

Abstract

A method for cooling a compressor motor ( 170 ) and a cooling circuit utilizing refrigerant that originates in the condenser ( 30 ) to cool a motor ( 170 ) and electromagnetic bearings ( 196, 206 ). The motor drives a compressor ( 20 ), while the electromagnetic bearings support the motor rotor ( 178 ) during operation of the compressor. Liquid refrigerant from the condenser is expanded into a two-phase mixture, passed over the stator, expanded a second time, passed over the bearings and between the stator and rotor, before being returned to an evaporator ( 50 ).

First claim

The invention claimed is:

1. A cooling circuit for a compressor motor ( 170 ) and bearings ( 194 , 204 , 196 , 206 ), the compressor motor ( 170 ) comprising a motor housing ( 174 ) with a cavity ( 190 ) that includes a stator ( 176 ) positioned within the housing ( 174 ) and a rotor ( 178 ) within the stator ( 176 ), and bearings centering the rotor within the stator, wherein the cooling circuit is characterized by:
a motor inlet ( 172 ) in the motor housing ( 174 ) providing refrigerant liquid to the motor ( 170 );
a spacer ( 180 ) extending 360° around the stator ( 176 ) and positioned between the motor housing ( 174 ) and the stator;
a gap between the spacer ( 180 ) and the stator ( 176 ) through which refrigerant liquid from the motor inlet ( 172 ) passes, the refrigerant liquid removing heat from the stator ( 176 ) and the motor housing ( 174 ) as the refrigerant changes state from liquid to a gas fluid;
an alignment pin ( 222 ) extending through the motor housing ( 174 ) and the stator ( 176 ), preventing relative rotation of the motor housing, the stator and the spacer ( 182 );
an expansion device ( 186 ) reducing the pressure of refrigerant fluid while converting it to a two phase mixture;
a first fluid passageway ( 188 ) that provides communications between refrigerant in the gap and the expansion device ( 186 );
a second fluid passageway ( 192 ) that receives two phase refrigerant mixture from the expansion device ( 186 ) while routing the refrigerant mixture to the motor housing cavity ( 174 );
a liquid outlet ( 200 ) to remove liquid refrigerant condensed from the mixture out of the motor housing ( 174 );
a stator/rotor annulus ( 202 ) between the stator and the rotor that receives the two phase refrigerant mixture from the second fluid passageway at a first end of the motor housing ( 174 ); and
an evaporation vent ( 208 ) removing refrigerant fluid from a second end of the motor housing after passing through the annulus ( 202 ) and cooling bearings, the rotor and the stator.

2. The cooling circuit of claim 1 wherein the gap between the spacer ( 180 ) and the stator ( 176 ) is a helical annulus ( 182 ) in communication with motor inlet ( 172 ).

3. The cooling circuit of claim 1 wherein the bearings include mechanical bearings ( 194 , 204 ).

4. The cooling circuit of claim 1 wherein the bearings include electromagnetic bearings ( 196 , 206 ) and mechanical back-up bearings ( 194 , 204 ).

5. The cooling circuit of claim 1 further including an electronics enclosure ( 212 ) mounted on the motor housing ( 174 ), the electronics enclosure cooled by refrigerant flowing through the motor housing ( 174 ).

6. A refrigeration system comprising a refrigerant, a compressor ( 20 ) for compressing the refrigerant and having a compressor motor ( 170 ), a condenser ( 30 ) in fluid communication with the compressor to receive compressed refrigerant from the compressor, an evaporator ( 50 ) in fluid communication with the condenser to receive refrigerant from the condenser, a first expansion device ( 40 ) intermediate the condenser and the evaporator to reduce the pressure of refrigerant liquid from the condenser to the evaporator, the condenser further in fluid communication with the compressor motor ( 170 ), providing refrigerant to the compressor motor to cool the motor, wherein the refrigeration system is characterized by:
a compressor motor ( 170 ), the compressor motor further comprising
a motor housing ( 174 ), the motor housing having a central cavity ( 190 ),
a stator ( 176 ) positioned within the motor housing cavity ( 190 ),
a rotor ( 178 ) positioned within the stator,
bearings ( 194 , 204 , 196 , 206 ) centering the rotor ( 178 ) within the stator ( 176 ) when the motor is operating;
a motor housing refrigerant inlet ( 172 ) receiving refrigerant from the condenser ( 30 ) and providing refrigerant liquid to the compressor motor ( 170 );
a spacer ( 180 ) extending 360° around the stator and positioned between the motor housing ( 174 ) and the stator ( 176 );
a gap between the spacer and the stator through which refrigerant liquid from the motor inlet ( 172 ) passes, the refrigerant liquid removing heat from the stator and the motor housing as the refrigerant changes state from liquid to a gas fluid;
an alignment pin ( 222 ) extending through the motor housing ( 174 ) and the stator ( 176 ), preventing relative rotation of the motor housing, the stator and the spacer ( 180 );
a second expansion device ( 186 ) reducing the pressure of refrigerant fluid while converting it to a two phase mixture;
a first fluid passageway ( 188 ) that provides communications between refrigerant in the gap and the second expansion device ( 186 ),
a second fluid passageway ( 192 ) that receives two phase refrigerant mixture from the second expansion device ( 186 ) while routing the refrigerant mixture to the motor housing cavity ( 190 );
a liquid outlet ( 200 ) in fluid communication with the evaporator ( 50 ) removing liquid refrigerant condensed from the mixture out of the motor housing ( 174 );
a stator/rotor annulus ( 202 ) between the stator ( 176 ) and the rotor ( 178 ) that receives the two phase refrigerant mixture from the second fluid passageway ( 192 ) at a first end of the motor housing; and
a vent ( 208 ) removing refrigerant fluid from a second end of the motor housing ( 174 ) to the refrigeration system between the first expansion device ( 40 ) and a compressor inlet after passing through the annulus ( 208 ) and cooling the bearings, the rotor and the stator.

7. The refrigeration system of claim 6 further including a third expansion device ( 41 ) positioned between the condenser ( 30 ) and the compressor motor ( 170 ) to reduce the pressure of refrigerant liquid from the condenser entering the motor inlet ( 172 ).

8. The refrigerant circuit of claim 6 wherein the gap between the spacer ( 180 ) and the stator is a helical annulus ( 182 ) in communication with motor inlet ( 172 ).

9. The refrigerant circuit of claim 6 wherein the motor housing ( 174 ) further includes a third fluid passageway ( 552 ) extending through the motor housing substantially parallel to a longitudinal central axis of the motor and in communication with motor cavity ( 554 ), receiving refrigerant entering motor cavity ( 190 ) through motor inlet ( 172 ), the refrigerant flowing through third fluid passageway ( 552 ) further cooling motor housing ( 174 ).

10. The refrigerant circuit of claim 9 wherein the third fluid passageway ( 552 ) is in further communication with the second expansion device ( 186 ), the second expansion device ( 186 ) expanding refrigerant fluid into a mist and discharging it into second fluid passageway ( 192 ).

11. The refrigerant circuit of claim 6 , further including a subcooler ( 32 ) that receives and cools refrigerant liquid before providing the refrigerant to the motor inlet ( 172 ).

12. A method for cooling a compressor motor ( 170 ) having electromagnetic bearings ( 196 , 206 ) in a refrigeration system utilizing a refrigerant and having a compressor ( 20 ) for compressing the refrigerant and having a compressor motor ( 170 ), a condenser ( 30 ) in fluid communication with the compressor to receive compressed refrigerant from the compressor, an evaporator ( 50 ) in fluid communication with the condenser to receive refrigerant from the condenser, a first expansion device ( 40 ) intermediate the condenser and the evaporator to reduce the pressure of refrigerant liquid from the condenser to the evaporator, the condenser further in fluid communication with the compressor motor ( 170 ), providing refrigerant to the compressor motor to cool the m

Assignees

• Johnson Controls Tech Co

Inventors

• Sommer Steven T
• Schreiber Jeb W
• Estes Steven J

Classifications

• F04D29/5806

  Cooling the drive system · CPC title

• F04D29/058

  magnetic; electromagnetic · CPC title

• H02K9/10

  by gaseous cooling medium flowing in closed circuit, a part of which is external to the machine casing · CPC title

• F04D29/584

  cooling or heating the machine (F04D29/5846, F04D29/5853 take precedence) · CPC title

• F25B31/008 Primary

  by injecting a liquid · CPC title