Reciprocating Pump

Abstract

A reciprocating pump ( 10 ) for pumping seawater or other fluid under high-pressure. The pump ( 10 ) has a pump body ( 11 ) defining an internal space ( 13 ) and an opening ( 18 ) onto the internal space. A plunger ( 25 ) extends through the opening ( 18 ) and into the internal space ( 13 ). A sheath ( 30 ) closes the opening ( 18 ) and embraces an inner portion of the plunger ( 25 ), whereby pumping chamber ( 33 ) is defined between the pump body ( 11 ) and the sheath ( 30 ). The sheath ( 30 ) is deformable in response to reciprocatory movement of the plunger ( 25 ) to effect volume change within the pumping chamber ( 33 ). The sheath ( 30 ) comprises a first portion ( 31 ) which is generally stable, and a second portion ( 32 ) which embraces the plunger ( 25 ) and which deforms through expansion and contraction upon reciprocatory movement of the plunger. The first portion ( 31 ) defines a mounting flange ( 35 ) clampingly engaged with the pump body ( 11 ). The sheath ( 30 ) incorporates a recess ( 45 ) adjacent the open end thereof. A reinforcement sleeve ( 47 ) is located in the recess ( 45 ), whereby a cavity is defined between the reinforcement sleeve ( 47 ) and the plunger ( 25 ). There is also provision for lubricating the interface between the sheath ( 30 ) and the plunger ( 25 ).

1 . A reciprocating pump comprising a body defining an internal space and an opening onto the internal space, an operating element extending through the opening and into the internal space, a sheath closing the opening and embracing an inner portion of the operating element, a pumping chamber defined between the body and the sheath, the sheath being deformable in response to reciprocatory movement of the operating element to effect volume change within the pumping chamber, and a cavity about the operating element adjacent the open end of the sheath. 
   
   
       2 . An reciprocating pump according to  claim 1  wherein the cavity comprises an annular cavity. 
   
   
       3 . An reciprocating pump according to  claim 1  wherein the cavity is defined between the periphery of the operating element and a surrounding surface. 
   
   
       4 . An reciprocating pump according to  claim 3  wherein the surrounding surface is defined by a reinforcement sleeve located in a recess within the sheath. 
   
   
       5 . An reciprocating pump according to  claim 4  wherein the reinforcement sleeve supports a wear ring in sliding engagement with the operating element. 
   
   
       6 . A reciprocating pump according to  claim 3  wherein the surrounding surface is defined by the open end portion of the sheath. 
   
   
       7 . A reciprocating pump according to  claim 6  wherein the open end portion of the sheath incorporates reinforcement for maintaining the end in an open condition spaced from the operating element. 
   
   
       8 . An reciprocating pump according to  claim 1  wherein the cavity is closed at the outer end thereof by a seal. 
   
   
       9 . A reciprocating pump according to  claim 1  wherein the operating element is configured as a plunger. 
   
   
       10 . A reciprocating pump according to  claim 1  wherein the open end of the sheath is configured to provide a mounting flange. 
   
   
       11 . A reciprocating pump according to  claim 1  wherein the sheath comprises a first portion which is generally stable, and a second portion which embraces the plunger and which deforms through expansion and contraction upon reciprocatory movement of the plunger. 
   
   
       12 . A reciprocating pump according to  claim 11  wherein the first portion provides the mounting flange. 
   
   
       13 . A reciprocating pump according to  claim 11  wherein the cavity is accommodated within the confines of the first portion. 
   
   
       14 . A reciprocating pump according to  claim 11 , wherein the second portion comprises a surface which confronts the plunger. 
   
   
       15 . A reciprocating pump according to  claim 14  wherein said surface is configured to accommodate lubricant. 
   
   
       16 . A reciprocating pump according to  claim 15  wherein the configuration of the surface for accommodating lubricant comprises formations on the surface. 
   
   
       17 . A reciprocating pump according to  claim 9  wherein the outer surface of the plunger is coated with a low-friction material, such as polytetrafluoroethylene. 
   
   
       18 . A reciprocating pump according to  claim 19  further comprising feed means for lubricant to be fed within the sheath. 
   
   
       19 . A reciprocating pump according to  claim 18  wherein the feed means delivers lubricant to the region adjacent the inner end of the sheath. 
   
   
       20 . A reciprocating pump according to  claim 19  wherein the feed means comprises a lubricant delivery path in the operating element. 
   
   
       21 . A reciprocating pump comprising a body defining an internal space and an opening onto the internal space, an operating element extending through the opening and into the internal space, a sheath closing the opening and embracing an inner portion of the operating element, a pumping chamber defined between the body and the sheath, the sheath being deformable in response to reciprocatory movement of the operating element to effect volume change within the pumping chamber, a recess in the sheath adjacent the open end thereof, a reinforcement sleeve located in the recess, whereby a cavity is defined between the reinforcement sleeve and the operating element. 
   
   
       22 . A reciprocating pump according to  claim 21  wherein the reinforcement sleeve supports a wear ring in sliding engagement with the operating element. 
   
   
       23 . A reciprocating pump according to  claim 21  wherein the cavity is closed at the outer end thereof by a seal. 
   
   
       24 . A reciprocating pump comprising a body defining an internal space and an opening onto the internal space, a plunger extending through the opening and into the internal space, a sheath closing the opening and embracing an inner portion of the plunger, a pumping chamber defined between the body and the sheath, the sheath being deformable in response to reciprocatory movement of the plunger to effect volume change within the pumping chamber, the sheath comprising a first portion which is generally stable and a second portion which embraces the plunger and which deforms through expansion and contraction upon reciprocatory movement of the plunger, the first portion defining a mounting flange clampingly engaged with the body. 
   
   
       25 . A reciprocating pump according to  claim 24  wherein a recess is provided in the first portion of the sheath adjacent the open end of the sheath, and wherein a reinforcement sleeve is located in the recess whereby a cavity is defined between the reinforcement sleeve and the plunger. 
   
   
       26 . A reciprocating pump comprising a body defining an internal space and an opening onto the internal space, a plunger extending through the opening and into the internal space, a sheath closing the opening and embracing an inner portion of the plunger, a pumping chamber defined between the body and the sheath, the sheath being deformable in response to reciprocatory movement of the plunger to effect volume change within the pumping chamber, and feed means for feeding lubricant into the region between the plunger and the sheath. 
   
   
       27 . A reciprocating pump according to  claim 26  wherein the feed means is adapted to deliver lubricant to the region adjacent the inner end of the sheath. 
   
   
       28 . A reciprocating pump according to  claim 27  wherein the feed means comprises a lubricant delivery path in the plunger. 
   
   
       29 . A sheath for a reciprocating pump according to  claim 26 . 
   
   
       30 . A sheath comprising a first portion defining a mounting flange and a second portion adapted to embrace a plunger received within the sheath, the second portion being adapted to expand and contract upon reciprocatory movement of the plunger. 
   
   
       31 . A sheath according to  claim 30  wherein the second portion comprises a surface adapted to confront the plunger, said surface being configured to accommodate lubricant. 
   
   
       32 . A sheath according to  claim 30  further comprising a recess in the first portion adjacent the open end thereof, the recess being adapted to receive a reinforcement sleeve. 
   
   
       33 . (canceled) 
   
   
       34 . (canceled)