Pump assembly

Abstract

A pump assembly (10) including two diesel engines (11) that are intended to operate at a relatively constant speed. The engines (11) each drive a variable displacement pump (12) that is preferably a swashplate pump. Fluid under pressure from each pump (12) drives an assembly (13) to pump a fluid such as a 95/5 emulsion, water and/or mud.

Description

TECHNICAL FIELD

[0001] The present invention relates to pump assemblies and more particularly but not exclusively to pump assemblies employed in the oil, gas and mining industry.

Background of the Invention

[0002] In the oil, gas and mining industry, pumps are employed to deliver a 95/5 emulsion, water and/or "mud", however these previously known pumps do not or have difficulty in controlling the flow rate and pressure of the water and/or mud delivered by the pump.

[0003] A further disadvantage of these known pumps is that frequently they are not tolerant in respect of contamination and cause considerable vibration.

OBJECT OF THE INVENTION

[0004] It is the object of the present invention to overcome or substantially ameliorate at least one of the above disadvantages.

SUMMARY OF THE INVENTION

[0005] There is disclosed herein a pump assembly including:

[0006] a variable volume pump to deliver a drive fluid under pressure;

[0007] a motor and pump device, said device including a motor portion and a pump portion, said motor portion being connected to said variable volume pump to receive said drive fluid so as to be driven thereby, said motor portion being adapted to receive a drive fluid under pressure, said motor portion including a cylinder and piston co-operating therewith to internally divide the cylinder into first and second variable volume motor chambers, the volume of said chambers being varied by movement of said piston longitudinally of said cylinder, a piston rod extending from said piston through said first chamber, a second piston rod, said second piston rod extending from said piston through said second chamber, a first pump cylinder operatively associated with said first piston rod to provide a first variable volume first pump chamber, a second pump cylinder, said second cylinder being operatively associated with said second piston rod to provide a variable volume second pump chamber; and

[0008] a control assembly including a sensor to provide a signal indicative of the displacement of said piston, and a controller operatively associated with said sensor to receive said signal and to control said variable displacement pump to thereby control said motor portion and therefore output from said pump portion.

[0009] Preferably, said variable volume displacement pump is a swashplate pump.

[0010] Preferably, said device includes a priming pump to delivery fluid to the cylinders of said pump portion under pressure.

BRIEF DESCRIPTION OF THE DRAWINGS

[0011] A preferred form of the present invention will now be described by way of example with reference to the accompanying drawings wherein:

[0012] FIG. 1 is a top plan view of a pump assembly;

[0013] FIG. 2 are schematic sectioned views of a motor and pump device employed in the pump assembly of FIG. 1; and

[0014] FIG. 3 is a schematic hydraulic circuit diagram of the hydraulic circuit of the assembly of FIG. 1.

[0015] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

[0016] In the accompanying drawings there is schematically depicted a pump assembly 10. The pump assembly 10 of this embodiment has two diesel engines 11 that are intended to operate at a relatively constant speed. However, it should be appreciated the diesel engines 11 could be replaced with electric motors.

[0017] The diesel engines 11 each drive a variable volume displacement pump 12. Most preferably each pump 12 is a swashplate pump and delivers drive fluid under pressure to a motor and pump device 13. This fluid under pressure is a drive fluid and drives each assembly 13 to pump a pump fluid such as a 95/5 emulsion, water and/or mud.

[0018] The motor and pump device 13 includes a motor portion 14 having a cylinder 15 that co-operates with a piston 16 to provide two variable volume motor chambers 17 into which the drive fluid under pressure is delivered from the pump 12 to drive the motor portion 14. The piston 16 is caused to reciprocate so as to drive piston rods 18 and 19. The piston rods 18 and 19 extend outwardly through the chambers 17 and form part of pump portion 20. The pump portion 20 includes two cylinders 21 and 22 that co-operate with the piston rods 18 and 19 to provide variable volume pump chambers 23 and 24. As the piston 16 reciprocates together with the piston rods 18 and 19 the volumes of the chambers 23 and 24 vary to cause pump fluid to enter and leave the chambers 23 and 24. The fluid enters and leaves the chambers 23 and 24 via inlet ports 25 having pilot operated one-way valves 26 so that fluid cannot flow outwardly through the port 25.

[0019] Fluid leaves the chambers 23 and 24 via outlet ports 27, the ports 27 having pilot operated one-way valves 28 so that fluid cannot enter the chambers 23 and 24 via the ports 27.

[0020] The chambers 17 each have a single port 29 via which the drive fluid enters and leaves the chambers 17.

[0021] The pumps 12 are connected to the device 13 by means of pipes 30. The pipes 30 extend to the ports 29. The device 13 has connected to it pipes 31 via which the fluid being pumped is delivered to the port 25 and ducted from the port 27.

[0022] The pumps 12 are controlled by valve assemblies 32 that essentially alter the angle of the swashplate to thereby determine the output of the pumps 12. In turn, the valves 32 are controlled by a programmable logic controller 33 used by an operator. The controller 33 receives signals from linear displacement transducers 34 installed in the cylinders 21. The transducers 34 detect the position of the piston rods 18 and generate a signal delivered to the controller 33. Accordingly, the controller 33 not only has information in respect of the position of the piston rods 18 and 19 but also their velocity. The controller 33 then generates a signal to control the valves 32 so that the pumps 12 have the desired output.

[0023] The pumps 12 draw the drive fluid from a reservoir 35 within which there is located a "breather" pouch 36 communicating with atmosphere by means of a vent 37. The pouch 36 compensates for changes in the volume of fluid in the reservoir 35.

[0024] Each of the pumps 12 has a purge valve and body drain from which fluid circulating through the pumps 12 is delivered to a heat exchanger 39 cooled by a motor driven fan 40. Accordingly, fluid is taken from the circuit associated with the pumps 12 to cool the fluid circulating therein.

[0025] The pumps 12 are operated so that as the cylinders of the pumps 12 rotate and engage the inclined swashplate, the cylinders cyclically go through a phases where they draw in fluid and exhaust fluid. The pumps 12 are co-ordinated so that as the cylinders of the pumps 12 go through their cycles in unison. This causes the piston 16 to reciprocate through a desired displacement determined by the controller 33.

[0026] Preferably, the pump assembly 10 is skid mounted to facilitate transportation by motor lorry.

[0027] The above described preferred embodiment has the advantage of providing the pipes 31 with a controlled flow by operation of the controller 33 which fluid is substantially constant. A still further advantage of the above described preferred embodiment is that it is contamination tolerant and minimizes vibration.

Claims

1. A pump assembly including: a variable volume pump to deliver a drive fluid under pressure; a motor and pump device, said device including a motor portion and a pump portion, said motor portion being connected to said variable volume pump to receive said drive fluid so as to be driven thereby, said motor portion being adapted to receive a drive fluid under pressure, said motor portion including a cylinder and piston co-operating therewith to internally divide the cylinder into first and second variable volume motor chambers, the volume of said chambers being varied by movement of said piston longitudinally of said cylinder, a piston rod extending from said piston through said first chamber, a second piston rod, said second piston rod extending from said piston through said second chamber, a first pump cylinder operatively associated with said first piston rod to provide a first variable volume first pump chamber, a second pump cylinder, said second cylinder being operatively associated with said second piston rod to provide a variable volume second pump chamber; and a control assembly including a sensor to provide a signal indicative of the displacement of said piston, and a controller operatively associated with said sensor to receive said signal and to control said variable displacement pump to thereby control said motor portion and therefore output from said pump portion.

2. The pump assembly of claim 1, wherein said variable volume displacement pump is a swashplate pump.

3. The pump assembly of claim 1, wherein said device includes a priming pump to delivery fluid to the cylinders of said pump portion under pressure.

4. The pump assembly of claim 2, wherein said device includes a priming pump to delivery fluid to the cylinders of said pump portion under pressure.