Pump

Abstract

In a pump, a main shaft ( 16 ) is rotatably supported by ball bearings ( 14, 15 ) in a casing ( 13 ) having a suction opening ( 11 ) and a discharge opening ( 12 ), an impeller ( 1 ) is connected to an end of the main shaft ( 16 ), and a canned motor ( 18 ) rotatably drives the impeller ( 17 ) through the main shaft ( 16 ). A front shroud ( 44 ) is provided at the front side in the axial center direction of the impeller ( 17 ), and a rear shroud ( 45 ) is provided at the rear side in the axial center direction. A predetermined gap ( 47 ) facing the axial direction is formed between the casing ( 13 ) and the front shroud ( 44 ), and sealing units ( 48, 49 ) facing the radial direction are provided between the casing ( 13 ) and the front shroud ( 44 ). This allows for extended life of the pump.

1 . A pump comprising:
 a casing having a suction opening and a discharge opening;   a main shaft rotatably supported by a ball bearing in the casing;   an impeller connected to an end of the main shaft; and   a canned motor capable of rotatably driving the impeller through the main shaft,   the pump increasing pressure of fluid suctioned in from the suction opening by rotation of the impeller and discharging the fluid from the discharge opening, wherein   a front shroud is provided at a front side in an axial center direction of the impeller, and a rear shroud is provided at a rear side in the axial center direction of the impeller;   a predetermined gap facing an axial direction is formed between the casing and the front shroud; and   a sealing unit facing a radial direction and being provided between the casing and the front shroud.   
     
     
         2 . The pump according to  claim 1 , wherein the sealing unit is arranged in plurality in the axial center direction of the impeller. 
     
     
         3 . The pump according to  claim 1 , wherein the casing includes a fluid outlet from the impeller communicated with the discharge opening through a diffuser and a volute chamber, and the diffuser contains a throttle portion. 
     
     
         4 . The pump according to  claim 3 , wherein a shape of the throttle portion is set corresponding to a fluid outlet angle at an outlet of the diffuser, and to a passage area ratio between the outlet of the diffuser and the volute chamber. 
     
     
         5 . The pump according to  claim 1 , further comprising a preload spring that applies a preload to the ball bearing, wherein the preload spring is formed by stacking a plurality of corrugated plates in a ring shape. 
     
     
         6 . The pump according to  claim 1 , wherein the impeller is capable of carrying supercritical CO 2  fluid or liquid CO 2  through rotational driving, and the pump is used as a circulation pump for cleaning a semiconductor.