Refrigerant pump and cooling device employing same

Abstract

A refrigerant pump employed in a semiconductor cooling device includes a sealed casing, an electric motor having a stator disposed outside the sealed casing and a rotor disposed within the sealed casing, a pump mechanism juxtaposed with the electric motor, and a drive shaft for transmitting a rotational force of the rotor to the pump mechanism. The stator is positioned closer to the pump mechanism than the rotor is.

What is claimed is:  
     
         1 . A refrigerant pump comprising: 
 a sealed casing;    an electric motor having a stator disposed outside the sealed casing and a rotor disposed within the sealed casing;    a pump mechanism juxtaposed with the electric motor; and    a drive shaft for transmitting a rotational force of the rotor to the pump mechanism,    wherein the stator is positioned closer to the pump mechanism than the rotor is.    
     
     
         2 . The refrigerant pump according to  claim 1 , wherein the drive shaft has a large-diameter portion having first and second end surfaces opposite to each other, the first end surface positioned remote from the electric motor having a higher precision than the second end surface.  
     
     
         3 . The refrigerant pump according to  claim 2 , wherein a surface of the drive shaft is carburized or nitrided.  
     
     
         4 . A refrigerant pump comprising: 
 a sealed casing;    an electric motor having a stator disposed outside the sealed casing and a rotor disposed within the sealed casing;    a pump mechanism juxtaposed with the electric motor;    a drive shaft for transmitting a rotational force of the rotor to the pump mechanism; and    a bearing for rotatably supporting the drive shaft,    wherein at least one of the drive shaft ant the bearing has a carburized or nitrided surface.    
     
     
         5 . A refrigerant-circulating cooling device comprising a refrigerant pump according to any one of  claims 1  to  4 , wherein the refrigerant pump is free from oil.