Waterpump

Abstract

An electrically driven waterpump includes a rotor having impellers for feeding fluid. The rotor is housed in a housing. The rotor includes: a working section located in the fluid and contacting the fluid in a main passage of the fluid stirred by the impellers; and a non-working section located in the fluid and apart from the main passage of the fluid. Water repellency is applied to at least either one of an outer surface of the non-working section or a plane of the housing confronting the outer surface of the non-working section with the fluid interposed, so that shear stress of the fluid is reduced, and pump efficiency is improved.

What is claimed is:  
     
         1 . An electrically driven waterpump comprising a rotor having impellers for feeding fluid, the rotor being housed in a housing, 
 the rotor including: a working section located in the fluid and contacting the fluid in a main passage of the fluid stirred by the impellers; and a non-working section located in the fluid and apart from the main passage of the fluid, wherein    water repellency is applied to at least either one of an outer surface of the non-working section or a plane of the housing confronting the outer surface of the non-working section with the fluid interposed,    whereby shear stress of the fluid is reduced.    
     
     
         2 . The waterpump according to  claim 1 , wherein: 
 the pump is a magnetic coupling pump including a stator in the housing; and    the rotor is provided in the non-working section thereof with a magnet section,    whereby the rotor is rotated by a rotating magnetic field generated by the stator.    
     
     
         3 . The waterpump according to  claim 2 , wherein the pump is an outer-rotor type magnetic coupling pump in which the stator is located near the rotation center of the rotor and the magnet section is located around the stator.  
     
     
         4 . The waterpump according to  claim 2 , wherein the pump is an inner-rotor type magnetic coupling pump in which the magnet section is located near the rotation center of the rotor and the stator is located around the magnet section.