Flow restricting devices in pumps

Abstract

Restriction of flow along a shaft by interposing a split ring in the annulus between the shaft and housing. When the ends of the split ring are separated, the effective diameter of the ring is increased and a clearance between the ID of the split ring and the shaft is maintained permitting flow. When the ends are released and allowed to come together the split ring closes the annular gap and restricts the flow. Also contemplated is the restriction of flow along a shaft by interposing an axially movable sleeve in the annulus between the shaft and housing. Flow through the annulus between the movable sleeve and the shaft is resisted by the clearance or features such as labyrinths, to thereby create a differential pressure from one end of the sleeve to the other.

1 . In a structure comprising a shaft member and a support structure through which the shaft member extends, an arrangement for restricting fluid flow along the shaft member relative to the support structure in at least one annular space defined between the shaft member and the support structure, said fluid flow restricting arrangement comprising: 
 a discontinuous ring member disposed about the shaft member;    said discontinuous ring member having two ends;    said discontinuous ring member being actuable between: 
 a first condition, wherein said ends are spaced apart over a first distance; and  
 a second condition, wherein said ends are spaced apart over a second distance, the second distance being less than the first distance;  
   wherein, in said first condition, a greater flow path for fluid is afforded, in the at least one annular space defined between the shaft member and the support structure, than in said second condition.    
   
   
       2 . The fluid flow restricting arrangement according to  claim 1 , wherein, in both said first and second conditions of said discontinuous ring member, sufficient clearance is provided for displacement of the shaft member with respect to the support structure.  
   
   
       3 . The fluid flow restricting arrangement according to  claim 1 , wherein, in said second condition, said ends of said discontinuous ring member converge to restrict fluid flow in the at least one annular space defined between the shaft member and the support structure.  
   
   
       4 . The fluid flow restricting arrangement according to  claim 1 , wherein said discontinuous ring member is in elastic deformation while in said first condition, thereby promoting actuation from said first condition to said second condition.  
   
   
       5 . The fluid flow restricting arrangement according to  claim 1 , further comprising an arrangement for promoting actuation of said discontinuous ring member from said first condition to said second condition.  
   
   
       6 . The fluid flow restricting arrangement according to  claim 5 , wherein said arrangement for promoting actuation comprises a spacer element disposed between said ends of said discontinuous ring member when said discontinuous ring member is in said first condition.  
   
   
       7 . The fluid flow restricting arrangement according to  claim 6 , wherein said spacer element is adapted to be materially compromised in response to at least one ambient condition and thereby promote convergence of said ends of said discontinuous ring member towards said second condition.  
   
   
       8 . The fluid flow restricting arrangement according to  claim 7 , wherein the at least one ambient condition includes at least one of: a temperature change and a change in fluid chemistry.  
   
   
       9 . The fluid flow restricting arrangement according to  claim 7 , wherein said spacer element comprises a metal alloy or a thermoplastic polymer.  
   
   
       10 . The fluid flow restricting arrangement according to  claim 5 , wherein said arrangement for promoting actuation comprises a mechanical actuator configured for holding said ends of said discontinuous ring member apart in said first condition and for facilitating convergence of said ends of said discontinuous ring member towards said second condition.  
   
   
       11 . The fluid flow restricting arrangement according to  claim 1 , further comprising an annular chamber for housing said discontinuous ring member, said annular chamber being sufficiently sized to accommodate both said first and second conditions of said discontinuous ring member.  
   
   
       12 . The fluid flow restricting arrangement according to  claim 1 , wherein said discontinuous ring member has a generally right triangular cross sectional shape.  
   
   
       13 . The fluid flow restricting arrangement according to  claim 12 , wherein said discontinuous ring member comprises a first side oriented substantially in parallel to a longitudinal axis of the shaft member and a second side oriented substantially in a radial direction with respect to a longitudinal axis of the shaft member.  
   
   
       14 . The fluid flow restricting arrangement according to  claim 13 , wherein: 
 said discontinuous ring member comprises a third side, extending between said first and second sides, oriented substantially at a non-right acute angle with respect to a longitudinal direction of the shaft member; and    said annular chamber comprises a conical surface for interfacing with said third side of said discontinuous ring member.    
   
   
       15 . The fluid flow restricting arrangement according to  claim 11 , wherein said discontinuous ring member has a generally rectilinear cross sectional shape.  
   
   
       16 . The fluid flow restricting arrangement according to  claim 1 , further comprising an arrangement for biasing said discontinuous ring member in a predetermined direction substantially in parallel to a longitudinal axis of the shaft member.  
   
   
       17 . In a structure comprising a shaft member and a support structure through which the shaft member extends, an arrangement for restricting fluid flow along the shaft member relative to the support structure in at least one annular space defined between the shaft member and the support structure, said fluid flow restricting arrangement comprising: 
 a sleeve member disposed about the shaft member;    said sleeve member being displaceable, in a direction generally parallel to a longitudinal axis of the shaft member, between a first position and a second position;    wherein, in said first position, a greater flow path for fluid is afforded, in the at least one annular space defined between the shaft member and the support structure, than in said second position.    
   
   
       18 . The fluid flow restricting arrangement according to  claim 17 , wherein said sleeve member is generally cylindrical in shape.  
   
   
       19 . The fluid flow restricting arrangement according to  claim 17 , wherein said sleeve member generally maintains an annular clearance with respect to the support structure in both said first and second positions.  
   
   
       20 . The fluid flow restricting arrangement according to  claim 19 , further comprising an arrangement for sealing the annular clearance of said sleeve member with respect to the support structure.  
   
   
       21 . The fluid flow restricting arrangement according to  claim 20 , wherein said sealing arrangement comprises an O-ring.  
   
   
       22 . The fluid flow restricting arrangement according to  claim 17 , wherein: 
 the shaft member comprises a fixed supplementary member configured for limiting further displacement of said sleeve member when said sleeve member is in said second position; and    the fixed supplementary member and said sleeve member combine to restrict fluid flow in the at least one annular space defined between the shaft member and the support structure when said sleeve member is in said second position.    
   
   
       23 . The fluid flow restricting arrangement according to  claim 22 , wherein the fixed supplementary member comprises a cylindrical appurtenance fixed to the shaft member which increases an effective diameter of the shaft member.  
   
   
       24 . The fluid flow restricting arrangement according to  claim 17 , wherein said sleeve member is configured to displace from said first position to said second position in response to a predetermined flow rate or flow condition.  
   
   
       25 . The fluid flow restricting arrangement according to  claim 17 , wherein said sleeve member further comprises internal deformations disposed adjacent the shaft member, said internal deformations being adapted to increase fluid flow resistance during displacement of said sleeve member between said first and second positions.  
   
   
       26 . The fluid flow restricting arrangement according to  claim 25 , wherein said internal deformations comprise circumferential grooves recessed into at least one surface of said sleeve member which faces the shaft member.  
   
   
       27 . The fluid flow restricting arrangement according to  claim 17 , further comprising: 
 a discontinuous ring member disposed about the shaft member;    said discontinuous ring member having two ends;    said discontinuous ring member being actuable between: 
 a first condition, wherein said ends are spaced apart over a first distance; and  
 a second condition, wherein said ends are spaced apart over a second distance, the second distance being less than the first distance;  
   wherein, in said first condition, a greater flow path for fluid is afforded, in the at least one annular space defined between the shaft member and the support structure, than in said second condition.    
   
   
       28 . The fluid flow restricting arrangement according to  claim 27 , wherein: 
 said sleeve member comprises an internal surface which faces the shaft member;    said sleeve member further comprises an annular chamber recessed into said internal surface of said sleeve member; and    said discontinuous ring member is disposed in said annular chamber recessed into said internal surface of said sleeve member.    
   
   
       29 . The fluid flow restricting arrangement according to  claim 28 , wherein: 
 said discontinuous ring member assumes said first condition at least when said sleeve member is in said first position; and    said discontinuous ring member assumes said second condition at least when said sleeve member is in said second position.    
   
   
       30 . A rotary pump comprising: 
 a motor;    a shaft member extending from said motor;    an impeller attached to a free end of said shaft member;    a housing which encloses a major portion of said shaft member;    said housing comprising a seal housing which circumscribes at least a portion of said shaft member, said seal housing including at least one sealing element for restricting fluid flow along said shaft member;    said motor being configured for rotating said shaft in a manner to drive said impeller; and    an arrangement for restricting fluid flow along the shaft relative to the seal housing in at least one annular space defined between said shaft member and said seal housing;    said fluid flow restricting arrangement comprising a discontinuous ring member disposed about said shaft member;    said discontinuous ring member having two ends;    said discontinuous ring member being actuable between: 
 a first condition, wherein said ends are spaced apart over a first distance; and  
 a second condition, wherein said ends are spaced apart over a second distance, the second distance being less than the first distance;  
   wherein, in said first condition, a greater flow path for fluid is afforded, in the at least one annular space defined between said shaft member and said seal housing, than in said second condition.    
   
   
       31 . The rotary pump according to  claim 29 , wherein said rotary pump comprises a chemical processing pump.  
   
   
       32 . The rotary pump according to  claim 30 , wherein said discontinuous ring member is in elastic deformation while in said first condition, thereby promoting actuation from said first condition to said second condition.  
   
   
       33 . The rotary pump according to  claim 30 , further comprising an arrangement for promoting actuation of said discontinuous ring member from said first condition to said second condition.  
   
   
       34 . The rotary pump according to  claim 33 , wherein said arrangement for promoting actuation comprises a spacer element disposed between said ends of said discontinuous ring member when said discontinuous ring member is in said first condition.  
   
   
       35 . The rotary pump according to  claim 33 , wherein said arrangement for promoting actuation comprises a mechanical actuator configured for holding said ends of said discontinuous ring member apart in said first condition and for facilitating convergence of said ends of said discontinuous ring member towards said second condition.  
   
   
       36 . A rotary pump comprising: 
 a motor;    a shaft member extending from said motor;    an impeller attached to a free end of said shaft member;    a housing which encloses a major portion of said shaft member;    said housing comprising a seal housing which circumscribes at least a portion of said shaft member, said seal housing including at least one sealing element for restricting fluid flow along said shaft member;    said motor being configured for rotating said shaft in a manner to drive said impeller; and    an arrangement for restricting fluid flow along the shaft relative to the seal housing in at least one annular space defined between said shaft member and said seal housing;    said fluid flow restricting arrangement comprising a sleeve member disposed about said shaft;    said sleeve member being displaceable, in a direction generally parallel to a longitudinal axis of said shaft member, between a first position and a second position;    wherein, in the first position, a greater flow path for fluid is afforded, in the at least one annular space defined between said shaft member and said seal housing, than in said second position.    
   
   
       37 . The rotary pump according to  claim 36 , wherein said rotary pump comprises a chemical processing pump.  
   
   
       38 . The rotary pump according to  claim 36 , wherein said sleeve member is generally cylindrical in shape.  
   
   
       39 . The fluid flow restricting arrangement according to  claim 36 , wherein: 
 said shaft member comprises a fixed supplementary member configured for limiting further displacement of said sleeve member when said sleeve member is in said second position; and    said fixed supplementary member and said sleeve member combine to restrict fluid flow in the at least one annular space defined between said shaft member and said seal housing when said sleeve member is in said second position.    
   
   
       40 . The fluid flow restricting arrangement according to  claim 36 , further comprising: 
 a discontinuous ring member disposed about said shaft member;    said discontinuous ring member having two ends;    said discontinuous ring member being actuable between: 
 a first condition, wherein said ends are spaced apart over a first distance; and  
 a second condition, wherein said ends are spaced apart over a second distance, the second distance being less than the first distance;  
   wherein, in said first condition, a greater flow path for fluid is afforded, in the at least one annular space defined between said shaft member and said seal housing, than in said second condition.