Valve assembly

Abstract

There is disclosed a valve assembly for a pump such as a dual-piston reciprocating pump, and to such a pump incorporating a valve assembly. In one embodiment, a valve assembly ( 10 ) is disclosed which includes a valve main body ( 98 ); a valve member ( 100 ) mounted for movement within the valve main body, to control the supply of an actuating fluid to a pump ( 10 ); a main valve inlet ( 81 ) formed in the valve main body, through which actuating fluid is supplied to the valve main body; and an inlet valve ( 83 ) for controlling the flow of actuating fluid through the main valve inlet into the valve main body. Providing a valve assembly with such an inlet valve facilitates accurate control of the flow of actuating fluid into the valve assembly. This in turn facilitates control of the flow of actuating fluid to a pump, thereby permitting one or more operating characteristics of the pump to be varied.

1 . A valve assembly for a pump, the valve assembly comprising: 
 a valve main body;    a valve member mounted for movement within the valve main body, to control the supply of an actuating fluid to a pump;    a main valve inlet formed in the valve main body, through which actuating fluid is supplied to the valve main body; and    an inlet valve for controlling the flow of actuating fluid through the main valve inlet into the valve main body.    
   
   
       2 . A valve assembly as claimed in  claim 1 , wherein the inlet valve is adjustable to permit at least one characteristic of the actuating fluid flowing into the valve main body to be varied.  
   
   
       3 . A valve assembly as claimed in  claim 1 , wherein the flow of actuating fluid to a pump to operate the pump is dependent upon a position of the valve member within the valve main body.  
   
   
       4 . A valve assembly as claimed in  claim 1 , comprising at least a first and a second primary pump flow port, for fluid communication between the valve assembly and a pump.  
   
   
       5 . A valve assembly as claimed in  claim 4 , wherein the primary pump flow ports serve for flow of actuating fluid to and from the pump, for actuating the pump.  
   
   
       6 . A valve assembly as claimed in  claim 4 , wherein the valve assembly is adapted to supply fluid to the pump through one of the primary pump flow ports and to return fluid from the pump to the valve assembly through the other one of said flow ports, depending upon the position of the valve member within the valve main housing.  
   
   
       7 . A valve assembly as claimed in  claim 4 , wherein in a first position of the valve member, fluid flows from the valve assembly to the pump through the first primary pump flow port, and returns to the valve assembly from the pump through the second primary pump flow port.  
   
   
       8 . A valve assembly as claimed in  claim 7 , wherein in a second position of the valve member, fluid flows from the valve assembly to the pump through the second primary pump flow port, and returns to the valve assembly from the pump through the first primary pump flow port.  
   
   
       9 . A valve assembly as claimed in  claim 1 , comprising a control system for controlling the position of the valve member, and thus for controlling flow of fluid to and from the pump.  
   
   
       10 . A valve assembly as claimed in  claim 9 , wherein the control system is fluid operated, and is adapted to selectively generate a pressure differential across the valve member, for moving the valve member between the first and second positions.  
   
   
       11 . A valve assembly as claimed in  claim 9 , wherein the control system comprises at least two control valves, and wherein the control valves are adapted to be operated by the pump.  
   
   
       12 . A valve assembly as claimed in  claim 11 , wherein the control valves are adapted to control the position of the valve member within the valve main body by selectively permitting bleed of a control fluid from the valve assembly.  
   
   
       13 . A valve assembly as claimed in  claim 11 , wherein the control valves are adapted to selectively permit fluid supply to a first end of the valve main housing and fluid bleed from a second, opposite end of the valve main housing, to generate a pressure differential across the valve member to move the valve member in a first direction.  
   
   
       14 . A valve assembly as claimed in  claim 13 , wherein the control valves are also adapted to selectively permit fluid supply to the second end of the valve main housing and fluid bleed from the first end, to generate a pressure differential across the valve member to move the valve member in a second, opposite direction.  
   
   
       15 . A valve assembly as claimed in  claim 9 , wherein the control fluid is the same fluid as is used to actuate the pump.  
   
   
       16 . A valve assembly as claimed in  claim 11 , wherein the control valves are mechanically operated and biased towards a closed position.  
   
   
       17 . A valve assembly as claimed in  claim 16 , wherein, in the closed positions of the control valves, the valve member is restrained against movement by fluid pressure.  
   
   
       18 . A valve assembly as claimed in  claim 16 , wherein the control valves are adapted to be opened by an actuating piston of the pump during movement thereof in a cycle of the pump.  
   
   
       19 . A valve assembly as claimed in  claim 11 , comprising a first control valve coupled to a first end of the valve housing, and a second control valve to a second, opposite end of the valve housing, by corresponding fluid lines.  
   
   
       20 . A valve assembly as claimed in  claim 19 , wherein the control valves are each coupled to a fluid pressure source, and wherein actuation of the first control valve supplies fluid to the first end of the valve housing, to move the valve member in a first direction, and further wherein actuation of the second control valve supplies fluid to the second end of the valve housing, to move the valve member in a second, opposite direction.  
   
   
       21 . A valve assembly as claimed in  claim 4 , wherein the primary pump flow ports are in selective fluid communication with the inlet, for the supply of actuating fluid from the valve assembly to the pump; and with an exhaust, for the discharge of spent actuating fluid from the valve assembly.  
   
   
       22 . A valve assembly as claimed in  claim 8 , wherein the valve member controls the flow of actuating fluid from the inlet to one of the primary pump flow ports, and from the other one of the primary pump flow ports to the exhaust, according to the position of the valve member.  
   
   
       23 . A valve assembly as claimed in  claim 1 , wherein the valve member is a shuttle valve mounted for translation relative to the valve main body, the shuttle valve comprising a plurality of flanges defining annular chambers within the valve housing.  
   
   
       24 . A valve assembly as claimed in  claim 1 , wherein the valve assembly is adapted to be provided separately from the pump and to be coupled to the pump via flow lines.  
   
   
       25 . A valve assembly as claimed in  claim 1 , wherein the valve assembly is adapted to be provided externally of the pump and to be coupled to the pump via flow lines.  
   
   
       26 . A pump assembly comprising: 
 a pump; and    a valve assembly as claimed in  claim 1 .    
   
   
       27 . A valve assembly for a pump, the valve assembly comprising: 
 a valve main body; and    a valve member mounted for movement within the valve main body, to control the supply of an actuating fluid to a pump;    wherein the valve main body is adapted to be provided separately from the pump.    
   
   
       28 . A valve assembly for a pump, the valve assembly comprising: 
 a valve main body; and    a valve member mounted for movement within the valve main body;    wherein the valve member is movable between a first position in which actuating fluid is supplied to a first end of an actuating cylinder of the pump and exhausted from a second, opposite end of the actuating cylinder, and a second position in which actuating fluid is supplied to the second end of the actuating cylinder and exhausted from the first end of the actuating cylinder, to thereby reciprocate an actuating piston of the pump back and forth within the actuating cylinder.    
   
   
       29 . A pump comprising: 
 an actuating cylinder;    an actuating piston mounted for reciprocating movement within the actuating cylinder;    a discharge cylinder;    a discharge piston coupled to the actuating piston and mounted for reciprocating movement within the discharge cylinder to successively draw fluid into and discharge fluid from the discharge cylinder; and    a valve assembly as claimed in  claim 1 .    
   
   
       30 . A pump comprising: 
 an actuating cylinder;    an actuating piston mounted for reciprocating movement within the actuating cylinder;    a discharge cylinder;    a discharge piston coupled to the actuating piston and mounted for reciprocating movement within the discharge cylinder to successively draw fluid into and discharge fluid from the discharge cylinder; and    a valve assembly as claimed in  claim 27 .    
   
   
       31 . A pump comprising: 
 an actuating cylinder;    an actuating piston mounted for reciprocating movement within the actuating cylinder;    a discharge cylinder;    a discharge piston coupled to the actuating piston and mounted for reciprocating movement within the discharge cylinder to successively draw fluid into and discharge fluid from the discharge cylinder; and    a valve assembly as claimed in  claim 28.