Centrifugal pump

Abstract

A centrifugal pump prevents a fluid from stagnating and so stops decreases in pump efficiency. An open impeller-type centrifugal pump includes pump vanes 12 that are connected via a vane boss 10 to an end part of a rotational shaft 8 , a casing 14 that is connected to an end part of the pump base part 6 and forms a fluid chamber R surrounding the pump vanes 12 , and an intake 16 and an outtake 18 that are formed in the casing 14 . The pump vanes 12 are composed of pump vanes 12 a to 12 c that are integrally formed with current plates 20 a to 20 c . The current plates 20 a to 20 c cause some of the fluid that enters via the intake 16 to flow downwards along the axial direction of the rotational shaft 8 . The fluid that flows along the current plates causes a centrifugal flow from an inner periphery to an outer periphery in a gap between a pump base part and the lower surfaces of the pump vanes.

What is claimed is:  
     
         1 . A centrifugal pump including a rotational shaft that is disposed on a pump base part, at least one pump vane that is radially connected via a vane boss to an end part of the rotational shaft, a casing that is connected to the pump base part and forms a fluid chamber surrounding the at least one pump vane, a fluid intake that is provided at a predetermined position on the casing, and a fluid outtake that is provided at a predetermined position on the casing, 
 the centrifugal pump further comprising stagnation preventing means for generating, in a gap between the pump base part and lower surfaces of the at least one pump vane, a fluid flow in a centrifugal direction that is directed towards the fluid outtake.    
     
     
         2 . A centrifugal pump according to  claim 1 , 
 wherein the stagnation preventing means is at least one current plate that is provided on the vane boss, the at least one current plate causing some of a fluid that enters via the fluid intake to flow in an axial direction towards the pump base part, causing acceleration in the fluid flowing in the axial direction, and making the fluid flow towards the gap between the pump base part and the lower surfaces of the at least one pump vane.    
     
     
         3 . A centrifugal pump according to  claim 2 , 
 wherein each of the at least one current plate is integrally formed with base parts of the at least one pump vane and is connected to the vane boss.    
     
     
         4 . A centrifugal pump according to  claim 2 , 
 wherein each of the at least one current plate is a wing-shaped member that is connected to the vane boss at a different position to base parts of the at least one pump vane.    
     
     
         5 . A centrifugal pump according to any of  claims 1  to  4 , 
 wherein a plurality of current channels, which extend radially from the rotational shaft and are bent on the radial direction, are formed in at least one of a surface of the pump base part, the lower surfaces of the at least one pump vane, and lower surfaces of the at least one current plate.  
 
     
     
         6 . A centrifugal pump including a pump vane in which a plurality of blades are disposed radially on a ring shaped first shroud, a casing that is connected to a pump base part and forms a fluid chamber surrounding the pump vane, a fluid intake that is provided at a predetermined position on the casing, and a fluid outtake that is provided at a predetermined position on the casing, 
 the centrifugal pump further comprising stagnation preventing means for generating, in a gap between a lower surface of the pump vane and the pump base part, a flow in a centrifugal direction that is directed towards the fluid outtake.    
     
     
         7 . A centrifugal pump including a pump vane where a plurality of blades are disposed radially on a ring-shaped first shroud and a disc-shaped second shroud with a central fluid passage hole is disposed on the blades, a casing that is connected to a pump base part and forms a fluid chamber surrounding the pump vane, a fluid intake that is provided at a predetermined position on the casing, and a fluid outtake that is provided at a predetermined position on the casing, 
 the centrifugal pump further comprising stagnation preventing means for generating, in a gap between a lower surface of the pump vane and the pump base part, a flow in a centrifugal direction that is directed towards the fluid outtake.    
     
     
         8 . A centrifugal pump according to any of claims  6  and  7 , 
 wherein the stagnation preventing means is at least one current plate that is disposed on the lower surface of the pump vane facing the pump base part, agitates fluid that stagnates in the gap between the lower surfaces of the pump vane and the pump base part, and generates the flow in the centrifugal direction towards the fluid outtake.  
 
     
     
         9 . A centrifugal pump according to any of claims  6  and  7 , 
 wherein a plurality of current channels, which extend radially from a center of rotation of the pump vane and are bent on the radial direction, are formed in at least one of a lower surface of the first shroud, a lower surface of the pump vane, and lower surfaces of the at least one current plate.  
 
     
     
         10 . A centrifugal pump according to any of claims  1 ,  6  or  7 , 
 wherein the fluid is blood.