method and device for cooling a motor

Abstract

The invention relates to a method and to a device for cooling a motor, the motor driving at least one, at least two-stage compressor ( 2 ) of a coolant circuit ( 1 ), which includes at least one first compression stage and a second compression stage ( 4 ), and a coolant is conducted through the coolant circuit ( 1 ), which is brought from a low pressure level to a medium pressure level in the first compression stage ( 3 ), and from the medium pressure level to a high pressure level in the second compression stage ( 4 ), and which is then expanded to the medium pressure level following the second compression stage ( 4 ) while outputting heat.

What is claimed is: 
     
         1 . A method for cooling a motor which drives at least one, at least two-stage compressor ( 2 ) of a coolant circuit ( 1 ), which includes at least one first compression stage ( 3 ) and a second compression stage ( 4 ), a coolant being routed through the coolant circuit ( 1 ), which is brought from a low pressure level to a medium pressure level in the first compression stage ( 3 ), and from the medium pressure level to a high pressure level in the second compression stage ( 4 ), and then is expanded to the medium pressure level following the second compression stage ( 4 ) while outputting heat,
 wherein the motor ( 5 ) is cooled by a two-phase coolant main flow, which has the medium pressure level.   
     
     
         2 . The method as recited in  claim 1 ,
 wherein the coolant main flow is split into a liquid coolant component and a gaseous coolant component after cooling of the motor ( 5 ), the gaseous coolant component being supplied to the second compression stage ( 4 ), and the liquid fluid component being supplied to the first compression stage ( 3 ) of the two-stage compressor ( 2 ).   
     
     
         3 . The method as recited in  claim 1  or  2 ,
 wherein the coolant is evaporated prior to the first compression stage ( 3 ) while absorbing heat, and is condensed following the second compression stage ( 4 ) while outputting heat. 
 
     
     
         4 . The method as recited in one of  claims 1  through  3 , wherein following the first compression stage ( 3 ), the coolant component is combined with the coolant component coming from the second compression stage ( 4 ) after outputting heat, prior to being utilized for cooling the motor ( 5 ). 
     
     
         5 . The method as recited in one of  claims 1  through  3 , wherein following the first compression stage ( 3 ), the coolant component is supplied directly to the second compression stage ( 4 ), the coolant component, which is gaseous after cooling of the motor ( 5 ), being combined with the coolant component coming from the first compression stage ( 3 ) and conveyed to the second compression stage ( 4 ), and the coolant that forms the coolant main flow and comes from the second compression stage ( 4 ) is used for cooling the motor ( 4 ) after outputting heat. 
     
     
         6 . A device, in particular a two-stage heat pump, climate-control device or cooling system, for implementing a method as recited in  claims 1  through  5 ,
 wherein the device has a motor ( 5 ) and a coolant circuit ( 1 ), in which a two-stage compressor ( 2 ) having a first compression stage ( 3 ) and a second compression stage ( 4 ) is situated, which compressor is able to be driven by the motor ( 5 ), and a motor cooling system is integrated into the coolant circuit ( 1 ) in such a way that a coolant main flow is able to flow through it, a phase separation element ( 12 ) being disposed downstream from the motor cooling system in the direction of the flow, which is connected via a suction gas line ( 17 ) for a gaseous coolant component to the second compression stage ( 4 ), and via a first line ( 16 ) for a fluid coolant component to the first compression stage ( 3 ) of the two-stage coolant compressor ( 2 ). 
 
     
     
         7 . The device as recited in  claim 6 ,
 wherein an evaporator ( 14 ) and possibly a throttle element ( 13 ) and possibly further components are situated in the first line ( 16 ) upstream from the first compression stage ( 3 ).   
     
     
         8 . The device as recited in  claim 6  or  7 ,
 wherein a capacitor ( 9 ) and possibly a throttle element ( 11 ) as well as possibly further components are situated in a second line ( 8 ) of the coolant circuit ( 1 ) downstream from the second compression stage ( 4 ). 
 
     
     
         9 . The device as recited in one of  claims 6  through  8 , wherein a mixing device is situated in the coolant circuit ( 1 ) upstream from the motor cooling system, which is connected to a pressurized gas line ( 6 ) coming from the first compression stage ( 3 ), and to the second line ( 8 ). 
     
     
         10 . The device as recited in one of  claims 6  through  8 , wherein the second line ( 8 ) is connected to the motor cooling system, and a pressurized gas line ( 6 ) coming from the first compression stage ( 3 ) discharges into the suction gas line ( 17 ) leading to the second compression stage ( 4 ). 
     
     
         11 . The device as recited in one of  claims 6  through  8 , wherein additional components are situated in a coolant line between the motor cooling system ( 5 ) and the phase separation element ( 12 ). 
     
     
         12 . The device as recited in one of  claims 6  through  11 , wherein the coolant compressor ( 2 ) has more than two compression stages ( 3 ,  4 ), and the method as recited in one of  claims 1  through  5  is used between two of the compression stages. 
     
     
         13 . The device as recited in one of  claims 6  through  11 , wherein it has at least two coolant compressors, and the method as recited in one of  claims 1  through  5  is used between the coolant compressors or between compression stages of the coolant compressor, possibly more than one motor being cooled.