Fluid pressure powered apparatus

Abstract

A fluid pressure powered apparatus comprises a double-acting member, a first pilot valve, a second pilot valve, and a switchable valve is disclosed. The double-acting member is operable between a first stroke end and a second stroke end by fluid pressure from the switchable valve. The first and second pilot valves are configured to establish a biasing fluid pressure to first and second bias surfaces, respectively, of the switchable valve. The first and second pilot valves are actuatable by the double-acting member when at the first and second stroke ends, respectively, to reduce the biasing fluid pressure on the first bias surface. In operation, the reduction of biasing fluid pressure on either the first bias surface or the second bias surface, respectively, triggers the switchable valve to switch between a first stroke position and a second stroke position, respectively. A method of reciprocating a fluid pressure powered apparatus is also disclosed.

1 . A fluid pressure powered apparatus comprising:
 a double-acting member operable between a first stroke end and a second stroke end by fluid pressure from a switchable valve;   a first pilot valve configured to establish a biasing fluid pressure to a first bias surface of the switchable valve, the first pilot valve being actuatable by the double-acting member when at or near the first stroke end to reduce the biasing fluid pressure on the first bias surface;   a second pilot valve configured to establish a biasing fluid pressure to a second bias surface of the switchable valve, the second pilot valve being actuatable by the double-acting member when at or near the second stroke end to reduce the biasing fluid pressure on the second bias surface; and   in which in operation the reduction of biasing fluid pressure on either the first bias surface or the second bias surface, respectively, triggers the switchable valve to switch between a first stroke position and a second stroke position, respectively.   
   
   
       2 . The fluid pressure powered apparatus of  claim 1  in which the double-acting member comprises a piston or a diaphragm. 
   
   
       3 . The fluid pressure powered apparatus of  claim 1 , further comprising a fluid pressure source configured to supply fluid pressure to at least the switchable valve. 
   
   
       4 . The fluid pressure powered apparatus of  claim 3 , in which the fluid pressure source is a fluid pressure pipeline. 
   
   
       5 . The fluid pressure powered apparatus of  claim 4  in which the fluid pressure source is further configured to supply fluid pressure from the fluid pressure pipeline to at least the switchable valve through a fluid pressure take-off. 
   
   
       6 . The fluid pressure powered apparatus of  claim 3 , further comprising:
 a first signal line in fluid connection between the first bias surface and the first pilot valve; and   a second signal line in fluid connection between the second bias surface and the second pilot valve.   
   
   
       7 . The fluid pressure powered apparatus of  claim 6 , further comprising:
 a first pilot line configured to supply the biasing fluid pressure to the first bias surface; and   a second pilot line configured to supply the biasing fluid pressure to the second bias surface.   
   
   
       8 . The fluid pressure powered apparatus of  claim 7  in which the first pilot line is configured to supply the biasing fluid pressure to the first bias surface through the first pilot valve and the first signal line. 
   
   
       9 . The fluid pressure powered apparatus of  claim 7  in which the second pilot line is configured to supply the biasing fluid pressure to the second bias surface through the second pilot valve and the second signal line. 
   
   
       10 . The fluid pressure powered apparatus of  claim 7  in which the first pilot line is connected to the first bias surface. 
   
   
       11 . The fluid pressure powered apparatus of  claim 10  in which the second pilot line is connected to the second bias surface. 
   
   
       12 . The fluid pressure powered apparatus of  claim 7  in which the first pilot line is connected to the first signal line. 
   
   
       13 . The fluid pressure powered apparatus of  claim 12  in which the second pilot line is connected to the second signal line. 
   
   
       14 . The fluid pressure powered apparatus of  claim 7  in which the first pilot line and the second pilot lines are connected to respective outlets of a shuttle valve configured to supply fluid pressure through an inlet of the shuttle valve to the first pilot line and the second pilot line. 
   
   
       15 . The fluid pressure powered apparatus of  claim 8  in which the first pilot line comprises a first flow restrictor. 
   
   
       16 . The fluid pressure powered apparatus of  claim 15  in which the second pilot line comprises a second flow restrictor. 
   
   
       17 . The fluid pressure powered apparatus of  claim 1  in which the fluid pressure source is further configured to supply the biasing fluid pressures to the first bias surface and the second bias surface. 
   
   
       18 . The fluid pressure powered apparatus of  claim 1 , in which the double-acting member is operatively connected to drive a pump. 
   
   
       19 . The fluid pressure powered apparatus of  claim 18 , in which the pump is a positive displacement pump. 
   
   
       20 . The fluid pressure powered apparatus of  claim 1  for use as a chemical injection pump. 
   
   
       21 . The fluid pressure powered apparatus of  claim 1  in which the first bias surface and the second bias surface are transverse. 
   
   
       22 . The fluid pressure powered apparatus of  claim 1  in which the first pilot valve is actuatable by the double-acting member when at or near the first stroke end to at least partially exhaust the biasing fluid pressure on the first bias surface to a first exhaust line. 
   
   
       23 . The fluid pressure powered apparatus of  claim 22  in which the first exhaust line is configured to exhaust to the switchable valve. 
   
   
       24 . The fluid pressure powered apparatus of  claim 22  in which the double-acting member and the first stroke end define at least part of a first variable chamber, and in which the first exhaust line is configured to exhaust to the first variable chamber. 
   
   
       25 . The fluid pressure powered apparatus of  claim 22  in which, during operation, the first pilot valve is configured to at least partially supply the biasing fluid pressure to the first bias surface through the first exhaust line when the first pilot valve is actuated by the double-acting member and after the reduction of biasing fluid pressure on the first bias surface has triggered the switchable valve to switch. 
   
   
       26 . The fluid pressure powered apparatus of  claim 22  in which the second pilot valve is actuatable by the double-acting member when at or near the second stroke end to at least partially exhaust the biasing fluid pressure on the second bias surface to a second exhaust line. 
   
   
       27 . The fluid pressure powered apparatus of  claim 26  in which the second exhaust line is configured to exhaust to the switchable valve. 
   
   
       28 . The fluid pressure powered apparatus of  claim 26  in which the double-acting member and the second stroke end define at least part of a second variable chamber, and in which the second exhaust line is configured to exhaust to the second variable chamber. 
   
   
       29 . The fluid pressure powered apparatus of  claim 26  in which, in operation, the second pilot valve is configured to at least partially supply the biasing fluid pressure to the second bias surface through the second exhaust line when the second pilot valve is actuated by the double-acting member and after the reduction of biasing fluid pressure on the second bias surface has triggered the switchable valve to switch. 
   
   
       30 . A method comprising:
 reciprocating a double-acting member using fluid pressure;   controlling the reciprocation of the double-acting member using a switch having at least two positions; and   controlling the switch by establishing biasing fluid pressures to a first bias surface and a second bias surface of the switch to maintain the switch in position, and selectively and temporarily reducing a corresponding one of the biasing fluid pressures to cause the switch to switch positions.   
   
   
       31 . The method of  claim 30  in which the double-acting member comprises a piston or a diaphragm. 
   
   
       32 . The method of  claim 30 , further comprises restricting the establishment of the corresponding one of the biasing fluid pressures after the selective and temporary reduction. 
   
   
       33 . The method of  claim 32  in which restricting comprises metering. 
   
   
       34 . The method of  claim 30  in which selectively and temporarily reducing further comprises at least partially exhausting the corresponding one of the biasing fluid pressures. 
   
   
       35 . The method of  claim 30  in which establishing further comprises supplying the biasing fluid pressures from at least one fluid pressure supply, and further comprising at least restricting the supply of the corresponding one of the biasing fluid pressures during the selective and temporary reduction. 
   
   
       36 . The method of  claim 35  in which at least restricting the supply further comprises preventing the supply. 
   
   
       37 . The method of  claim 35  in which supplying further comprises supplying the biasing fluid pressures through outlets of a shuttle valve. 
   
   
       38 . The method of  claim 30  in which selectively and temporarily reducing further comprises:
 reducing the biasing fluid pressure to the first bias surface when the double-acting member is at or near a first stroke end; and   reducing the biasing fluid pressure to the second bias surface when the double-acting member is at or near a second stroke end.   
   
   
       39 . The method of  claim 38  in which the switch is a valve and reciprocating further comprises reciprocating the double-acting member using fluid pressure from the switch. 
   
   
       40 . The method of  claim 39  in which selectively and temporarily reducing further comprises at least partially exhausting the corresponding one of the biasing fluid pressures to the switch. 
   
   
       41 . The method of  claim 40 , further comprising at least partially restoring the corresponding one of the biasing fluid pressures that has been selectively and temporarily reduced when the double-acting member is still at or near the respective one of the first stroke end and the second stroke end, and the switch has switched positions. 
   
   
       42 . The method of  claim 30  in which the switch is a valve and reciprocating further comprises reciprocating the double-acting member using fluid pressure from the switch. 
   
   
       43 . The method of  claim 30  in which the switch is controlled by at least one pilot valve. 
   
   
       44 . The method of  claim 30  in which reciprocating the double-acting member comprises alternating the direction of a fluid pressure differential across the double-acting member. 
   
   
       45 . The method of  claim 44  in which the double-acting member further comprises a first stroke surface and a second stroke surface, and in which alternating the direction of a fluid pressure differential across the double-acting member comprises:
 establishing the fluid pressure differential in a first direction by supplying fluid pressure to the first stroke surface and exhausting fluid pressure from the second stroke surface; and   establishing the fluid pressure differential in a second direction by supplying fluid pressure to the second stroke surface and exhausting fluid pressure from the first stroke surface.   
   
   
       46 . The method of  claim 45  in which exhausting fluid pressure from at least one of the first stroke surface or the second stroke surface comprises exhausting into an exhaust. 
   
   
       47 . The method of  claim 46  in which selectively and temporarily reducing further comprises at least partially exhausting the corresponding one of the biasing fluid pressures into the exhaust. 
   
   
       48 . The method of  claim 45  in which selectively and temporarily reducing further comprises at least partially exhausting the corresponding one of the biasing fluid pressures to:
 the second stroke surface when the fluid pressure differential is in the first direction; and   the first stroke surface when the fluid pressure differential is in the second direction.   
   
   
       49 . The method of  claim 30  used to drive a pump. 
   
   
       50 . The method of  claim 49  used to drive a positive displacement pump. 
   
   
       51 . The method  claim 49  used for chemical injection. 
   
   
       52 . The method of  claim 30  in which at least one of the fluid pressure and the biasing fluid pressures are supplied from a pipeline. 
   
   
       53 . A fluid pressure powered pump comprising:
 a fluid pressure valve having a first surface and a second surface, the fluid pressure valve switchable between a first position and a second position;   a double-acting member operable by fluid pressure from the fluid pressure valve:
 through a first stroke towards a first end in the first position; and 
 through a second stroke towards a second end in the second position; and 
   a first pilot valve and a second pilot valve configured in operation to establish biasing fluid pressures to the first surface and the second surface, respectively, during both the first stroke and the second stroke, the first pilot valve and the second pilot valve being actuatable by the double-acting member at or near the first end and the second end, respectively, to reduce the biasing fluid pressure on the first surface and the second surface, respectively, to switch fluid fluid pressure valve positions.   
   
   
       54 . A method of driving a fluid pressure powered apparatus having a double-acting member operated by fluid pressure from a switchable valve, the method comprising:
 supplying biasing fluid pressures to a first bias surface and a second bias surface of the switchable valve to maintain the switchable valve in a first position;   establishing a first fluid pressure differential across the double acting member towards a first stroke end to move the double-acting member towards the first stroke end;   reducing the biasing fluid pressure on the second bias surface when the double-acting member reaches the first stroke end to cause the switchable valve to shift to a second position;   supplying biasing fluid pressures to the first bias surface and the second bias surface to maintain the switchable valve in the second position;   establishing a second fluid pressure differential across the double acting member towards a second stroke end to move the double-acting member towards the second stroke end; and   reducing the biasing fluid pressure on the first bias surface when the double-acting member reaches the second stroke end to cause the switchable valve to shift to the first position.   
   
   
       55 . The method of  claim 54 , further comprising repeating the method.