This invention relates to improvements in and relating to a hydraulically actuated bore and well pump, and in particular it relates to pumps of the type in which an actuating mechanism for a pump which is situated beneath the liquid level in a bore or well and is adapted to reciprocate a piston within the submerged pump to raise liquid to the surface. According to the older types of pump it was customary to use a windmill or pump jack at the surface of the bore or well and to have a mechanical connecting rod between the operating mechanism and the piston of the submerged pump to actuate the piston during its pumping action.

In an earlier system I used a submerged pump which, instead of being connected by mechanical coupling means to the actuating mechanism at the surface of the bore or well, I used a hydraulic con¬ nection so that pressure in an actuating hose moves the piston in one direction to initiate a pumping action and return was by the weight of water in the system, the balance being such that the pumping action was under control of pressure in a hose which was intermittently applied on one stroke of the pump and on the other stroke of the pump the piston was returned by water pressure for the next stroke.

I also experimented with a system in which two coupled pistons were used, one of which was a larger piston adapted to draw water on one stroke into the barrel of the pump and to deliver the water on the next stroke of the piston through a discharge pipe, the weight of fluid in the delivery line forcing the smaller piston downwardly carrying the larger piston

with it to draw liquid into the space above the larger piston in readiness for the next lifting action. For this device to operate it was necessary to raise the discharge pipe above the level of the piston mechanism at the surface which actuated the submerged pump to obtain the necessary pressure to return the pistons.

The present invention related generally to these systems but combines the advantages of the foregoing specifications with a double-acting driving system at the bore or well head, and with a double- acting slave system in the submerged pump the object being to provide a simpler and more effective system.

The invention utilises two driving pistons in barrels at the head of the bore or well which are connected to the submerged pump in the bore or well, the arrangement resulting in a balanced system of high efficienc .

The present invention comprises a hydraulically actuated bore or well pump in which a submerged pump unit comprises a pumping piston in a barrel having a foot valve to admit liquid to the barrel and a non¬ return valve at the piston, and in which the piston is connected to a slave unit, comprising a slave piston in a barrel coaxial with the first barrel, by a hollow connecting rod opening through the pumping and slave piston and communicating with a delivery line adapted to discharge liquid to the surface of the bore or well, and in which a driving unit at the bore or well surface comprises piston and barrel means adapted to actuate the slave piston through a pressure line between the

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driving unit and the slave piston, characterised in that the said driving unit is double-acting to impart both up and down movement to the pumping and slave pistons as the driving unit piston means are reciprocated, further characterised by valve means in the delivery line to control outflow from the delivery line to make possible drive in both directions using only at least a pressure line and a delivery, line.

According to a preferred construction the invention comprises a hydraulically actuated bore or well pump in which a submerged pump comprises a first upper barrel and a second lower barrel with the space of one barrel isolated from the other by a dividing wall, an apertured piston being positioned in each barrel interconnected by a hollow connecting rod so that the space within the upper barrel above the piston therein which forms a slave piston is in communication with the space in the lower barrel on both sides of the piston therein which forms a pumping piston, the hollow connecting rod passing sealingly through the dividing wall, the lower end of the hollow connecting rod being apertured into the space in the lower barrel above the pumping piston therein, characterised in that the aperture through the pumping piston in the lower barrel has a non-return valve to admit fluid from below the pumping piston into the space above the piston and Into the hollow connecting rod, a non-return valve being provided in the lower end of the lower barrel, further characterised by a pair of remote barrels at the surface having oppositely acting interconnected driving pistons therein whereby to reciprocate the pistons of the submerged pump, a delivery line connecting the top of the upper barrel with a surface delivery point, a pressure line connect-

ing the lower end of the upper barrel with one of the remote barrels, an auxiliary pressure line connecting the delivery line with the other surface barrel, a valve located in the delivery line between the auxiliary pressure line and the delivery point in communication with the first pressure line whereby the valve opens the delivery line when liquid flows upwardly in the delivery line but pressurises the delivery line on the return stroke, and means to actuate the remote surface pistons.

In order that the invention will be fully under¬ stood, embodiments thereof will now be described with reference to the accompanying drawings in which:

FIG. 1 shows somewhat schematically a transverse section of the system of this invention showing the pistons of the surface driving unit actuated by hydraulic motor means and showing in principle a submerged pump and its actuation, the interconnecting lines being shown as passing down the bore or well independently but the pressure line can be positioned within the delivery line.

FIG. 2 is a fragmented longitudinal section showing a mechanical drive in place of the hydraulic motor means.

Referring first to the driving unit 1 at the surface of the bore or well for actuating the pump unit 2, a pair of barrels 3-4 are supported in a trough 5, which barrels 3-4 have within them pistons 6-7 inter¬ connected by a rod 8 so arranged that when the rod 8 moves the pistons 6-7 in one direction liquid is displaced from the barrel 3 at one end but when the rod

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8 is moved in the opposite direction, liquid is displaced from the barrel 4 at its other end. This unit thus forms a double-acting surface driving unit.

In the form illustrated in FIG. 1 a hydraulic motor is used to provide the reciprocation, but a crank or other drive means can be used as illustrated in FIG. 2, or the hydraulic motor may be replaced by pneumatic motor means or by electrical actuating means such as a linear motor.

As shown in FIG. 1 the rod 8 between the pistons is coupled by a mechanical link 9 to a second rod 10 parallel to the first rod 8 and this rod 10 connects a pair of pistons 11-12 of hydraulic motor means 13 in barrels 14-15 arranged parallel to the first pair of barrels 3-4 so that when the second rod 10, which is the driver rod, is actuated, it moves the rod 8 which interconnects the pistons 6-7 which displace the fluid for the driving action.

The hydraulic motor means 13 have their pistons 11-12 operated by hydraulic fluid from a suitable supply tank 18 by a hydraulic pump 19 of any usual or approved type, acting through a solenoid controlled valve 20 which is regulated in its position by a pair of micro-switches 21-22 positioned so that, as the mechanical link 9 between the two rods 8-10 reaches the one micro—switch, the direction of movement is reversed, and when it reaches the other micro-switch the direction is again reversed and so on, this then ensuring that the driver pistons 11-12 which have their rod 10 coupled to the rod 8 of the surface driving unit, causes the pistons 6-7 to displace the liquid to cause reciprocation of the driving pistons 6-7.

The control of the motor means 13, whether they are hydraulic, pneumatic, or electrical can be con¬ trolled to vary the speed of the driving means such as by having a speed variation at the end of one or each stroke to avoid water hammer, and for this purpose a microprocessor 23 can be coupled to the control means.

The submerged pump unit has an upper barrel 25 and a lower barrel 26, these barrels 25 and 26 having the same volume displacement as the barrels 3 and 4.

The barrel 25 has in it a slave piston 27, the lower barrel 26 having in it a pumping piston 28, the pistons 27 and 28 being interconnected by a hollow connecting rod 30 which passes through a central dividing wall 31 and having a seal 32, and both the upper slave piston 27 and the lower pumping piston 28 have openings therethrough but the lower pumping piston 28 has a check valve 33 to allow only upward flow therethrough.

A foot valve 34 allows liquid flow through a ¹¹ opening 35 into the lower part of the chamber 36 formed by the barrel 26 while ports 37 in the hollow connecting rod 30 allows liquid from the hollow connecting rod to flow into the space 38 above the pumping piston 28 in the barrel 26.

The pressure line is designated 40 and the delivery line 42.

The barrel 3 of the surface driving unit 1 is in communication with the space 44 in the cylinder 25 below the slave piston 27 through an annular space 45 between the sleeve 46 and the barrel 25, while the

delivery line 42 connects to the chamber 48 in the barrel 25 above the slave piston 27.

The delivery line 42 has in it a valve 50 which is loaded to a closed position by a spring 51 but Is urged from the seat 52 in the chamber 53 by pressure on a piston 54 from the pressure line 40 acting through a branch line 55.

The purpose of the valve 50 in the chamber 53 in the delivery line 42 is to close off outflow from the delivery line 42 during the time that liquid in the pressure line 40 is lifting the pistons 27 and 28 to allow outflow of the liquid being pumped from the discharge point but closes off the flow when the pistons 27 and 28 return after a lifting stroke.

Return of the pistons 27 and 28 is by pressure in the delivery line 42 obtained from outward movement of the piston 7 in the barrel 4 through the auxiliary pressure line 57 which is connected to place the barrel 4 into communication with the chamber 53 on the submerged pump unit 2 side of the valve 50.

In the drawings the solid line arrows show flow and movement direction during the ^' lifting stroke in which case the ^" valves 50 and 34 are open and the valve 33 is closed. The dotted line arrows show the flow and movement direction on the return stroke when the valves 50 and 34 are closed and the valve 33 is open-

It should be noted also that the piston 27 could have a valve, not shown, to close when return pressure is applied to the slave unit.

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The drive shown in FIG. 2 can replace the hydraulic motor means 13 and comprises a crank 60 connected by a rod 61 to a cross-head 62 slidable on a guide rod 63 secured to the barrels 3a and 4a, the cross-head 62 being fixed to the rod 8a interconnecting the pistons in the barrels 3a and 4a.

In this case the pumping speed of the driving unit is controlled by the crank 60, but as stated earlier, in the form shown in FIG. 1, or in the case of replacε- ment of the hydraulic motor unit by a pneumatic unit or for instance a linear electric motor unit, the pumping speed can be controlled Incrementally by use of for instance the microprocessor 23, so that the best pumping rate can be achieved to avoid water hammer or similar problems.

From the foregoing it will be realised that a simple and effective liquid pump results which has an improved double-acting mechanism for actuating the submerged pump which, because it is also double- action results In a balanced system having a high pumping efficiency with high control of the actual - pumping and return strokes if this is required.

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