Pump device

Abstract

A pump device has an impeller rotatable in a pump space, a rotational shaft interconnecting a rotational drive source and the impeller, a rotational shaft casing having a bearing assembly and/or a seal assembly, a first blocking flow mechanism, having a discharge section for discharging a portion of a main delivery liquid introduced from the pump space as a first blocking flow, for preventing a second blocking flow containing fine particles produced by the bearing assembly and/or the seal assembly from being entrained into the main delivery liquid, and a second blocking flow mechanism for combining the second blocking flow with the first blocking flow and discharging the second blocking flow from the discharge section while preventing the first blocking flow from being introduced.

1 . A pump device comprising: 
 an impeller rotatable in a pump space;    a rotational shaft interconnecting a rotational drive source and said impeller;    a rotational shaft casing having a bearing assembly and/or a seal assembly;    a first blocking flow mechanism, having a discharge section for discharging a portion of a main delivery liquid introduced from said pump space as a first blocking flow, for preventing a second blocking flow containing fine particles produced by said bearing assembly and/or said seal assembly from being entrained into the main delivery liquid; and    a second blocking flow mechanism for combining said second blocking flow with said first blocking flow and discharging said second blocking flow from said discharge section while preventing said first blocking flow from being introduced.    
   
   
       2 . A pump device according to  claim 1 , wherein said first blocking flow mechanism has a first blocking flow passage defined between said rotational shaft and an inner circumferential surface of said rotational shaft casing, and said second blocking flow mechanism has a second blocking flow passage defined between said rotational shaft and an inner circumferential surface of said rotational shaft casing, said first blocking flow passage and said second blocking flow passage being disposed in respective positioned on both sides of said discharge section, said second blocking flow passage being supplied with an inactive liquid as said second blocking flow from a second blocking flow supply port which is open into said second blocking flow passage.  
   
   
       3 . A pump device according to  claim 1 , wherein said discharge section comprises a blocking disk mounted on said rotational shaft and a disk chamber defined in said rotational shaft casing and housing said blocking disk therein.  
   
   
       4 . A pump device according to  claim 3 , wherein a labyrinth is provided in said disk chamber between an inner circumferential surface of said disk chamber and said blocking disk.  
   
   
       5 . A pump device according to  claim 2 , wherein said second blocking flow has a higher liquid pressure than said first blocking flow at said second blocking flow supply port.  
   
   
       6 . A pump device according to  claim 2 , wherein said second blocking flow passage is filled at all times with the inactive liquid supplied from said second blocking flow supply port.  
   
   
       7 . A pump device according to  claim 1 , wherein said first blocking flow is discharged from said discharge section at a rate higher than said second blocking flow, the rate of said second blocking flow being at least 1.5 when the rate of said first blocking flow is 1.