US2575308A - Hydraulic jack - Google Patents

Description

Nov. 13, 1951 l. M. WHITE 2,5 75,308

HYDRAULIC 4JACK Filed Aug. 5, 1946 1N VEN TOR. /e/q Mofa/4N M/f-f/rf BYZ Patented Nov. 13, `v1951 UNITED STATES PATENT v( )FFICIE Application August 5, 1946, SerialNo. 688,498

8 Claims. (Cl. 60-51) My invention relates to means especially designed for use in connection with deep well reciprocating pumps for the purpose of operating the pump rod to discharge pumped fluid from the well. Devices of this nature have come into use in deep petroleum wells in which it is necessary to supply a pumping structure of considerable capacity capable of operating at relatively high pressures. There is customarily employed a pumping jack including a cylinder having a reciprocating piston therein. The cylinder is periodically supplied with hydraulic fluid, such as oil, from a storage tank through the medium of an actuating pump and is alternately deprived of oil by the pump, the oil being returned to the storage tank. To secure a partial balance of the reciprocating parts the storage tank customarily is closed and is provided with an air cushion operating at a suitable pressure so that the load on the oil pump is approximately constant. It has been found in practice that the air cushion tends to become depleted due`to loss of air from various causes.

It is therefore an object of my invention to provide in a hydraulic jack mechanism a means for maintaining a suitable body of air in the balancing tank.

It is another object of my invention to provide a hydraulic jack in which the pressure air supply is automatic.

A further object of the invention is to provide a hydraulic jack in which the air supply can readily be adapted to mechanism already available in the hydraulic jack assembly.

A further object of the invention is to provide in a hydraulic jack an air supplying structure capable of regulating the supplied air pressure.

An additional object of the invention is to provide a hydraulic jack of a generally improved character.

Other objects together with the foregoing are attained in the embodiment of the invention disclosed in the accompanying drawing, in which the ligure is a diagrammatic disclosure of the hydraulic jack of my invention, incorporating the air supplying means therein.

While the hydraulic jack of my invention is susceptible to utilization in a number of different environments and is capable of variation depending upon various operating characteristics, it has successfully been embodied as -shown in the accompanying diagram. Some of the structures diagrammed are more fully illustrated in the patent of Fred H. Rued, 2,481,623, issued September 13, 1949, and entitledv Pumping Jack. The

lli

mechanism includes a main jack cylinder 6 usually installed vertically over a well to be pumped and serving as a housing for a reciprocable piston 'I, secured to the end of a rod 8 connected to the sucker rod of a deep well pump. A suitable amount of oil under appropriate pressure is supplied to or withdrawn from the cylinder 6 beneath the piston 'I through a lower port 9 and a connecting conduit I I extending to a port I2 in a main valve, generally designated I3. The main valve I3 is primarily a cylindrical housing having a number of different ports and passages therein and containing a valve shuttle I4. Incorporated in the valve shuttle is a central spindle I6 and a valve head I'I, in one position of the Valve disposed to one side'of theport I2, and a similar valve head I8 Vin that positionv of the valve dis-v posed on the other side of the port I2. A head i9 comparable to the head I'I is in this positionv of the valve disposed adjacent one end of the valve housing.

The arrangement of the port I2, with respect to the heads I'I and I8 -and also with respect to an inlet port 2| is such that, in the illustrated position of the valve, oil from a suitably driven main pump 22 is discharged into the cylinder 6. The oil is received bythe pump 22 from a balancing tank 23 through a conduit 24 'and through ports 26 and 21 disposed inV this position of the valve between the heads I8 and I 9 and through-a conduit 28 to a pump inlet pipe 29. Thus oil from the balancing tank 23 is drawn by the pump 22 through the control valve I3 and is then forced again through the control valve into the jack cylinder E, so that during the operation of the pump under these circumstances oil under pressure is supplied beneath the piston 'I and the rod 8 is lifted. b

The lifting action of the piston I continues until the piston has overridden a selected one of a plurality of ports 3I, 32, 33 and 34 in the cylinder 8. The effective one 33 of such ports is connected through a rotary selector valve 36 and through a check valve 31, aiiording iiow in the directionv of the arrow, to a conduit 38,extending to a pilot" valve. A"

The pilot` valve is primarily a body 39 having a cylindrical bore-'within whichop'erates' a shuttle'- 4I having a central stem 42 'Sat one end of which'.v a head 43 is disposed. Pressure' from the conduit 38 acts through a port I4-upon the head Y43 and tends to translate the shuttleY 4I to the'right in' the figure. This pressure is in part opposed by* pressure upon a head 46 atv the end of the stem 42. The head 46 slides withina=`chamber 4'I-forining 1:

an extension of the valve body 39 and connected by a conduit 48 to the interior of the balancing tank 23. The body 49 of oil in the tank is eiective to transmit the interior tank pressure through the conduit 48 against the head 46 to oppose the pressure upon the head 43. Leakage past the head 46 discharges through a port 5| into a conduit 52 leading to a sump 53 opento atmospheric pressure. Leakage past the head 43 discharges through a port 54 into a line 56 likewise leading to the sump 53. Due to the fact that the diam' eter of the head 43 is much greater than that 0f the head 46, whereas the unit pressure acting against both heads is approximately the same, there is a resultant unbalanced pressure effective under the described conditions to move the shuttle 4| to the right, as seen in the figure. When such motion is accomplished, the shuttle 4I is shifted so that the head 46, the head 43, and an intermediate head 51 are all moved to the opposite extreme position. The head 51 then lies on the right side of a pressure line 58 extending to the valve body 39 from a scavenge pump 59 suitably operated from amotor (not shown).

The scavenge pump withdraws hydraulic fluid from the sump 53 through an intake duct 6I. From the discharge conduit 58 a by-pass line 62 leads to a relief valve 63 closed normally by a spring 64. The valve 63 is opened by a pressure in excess of a predetermined pressure to permit flow from the conduit 62 through the valve 63 and through a return conduit 66 to the sump 53. With this arrangement when the pressure is excessive the scavenge pump 59 is effective merely to circulate the excess pressure Voil locally from the sump through the pump but when the pressure is less than a predetermined amount the scavenge pump discharges only through the line 58 into the interior of'the pilot valve body 39 through a port 61. When the head 51'is on the right hand side of such port the pressure fluid then iiovvs from the'pilot valve body 39 through a discharge port 68 into a conduit 69 leading to a port 1I in one end of the body of the main valve I3. Thus the end of the head i9 is exposed to the scavenge pump pressure. The main valve shuttle I4 is substantially unbalanced as its opposite head I1 is provided with a discharge port 12 leading through a conduit 13 back to a port 14 in the pilot valve body 39. v

When the pilot valve shuttle is in a position opposite rto that shown, iiow from the conduit 13 is then through the body 39 from a port 18 therein and through a short line 11 into the discharge conduit 52 leading back to the sump 53. Because ofthe unbalanced pressure existing on the main valve shuttle I4 it is translated from the position shown in the figure to a position in the other extreme end of the valve body. Thus, when the piston 1 overruns the port 33 there is produced a translation-of the shuttle 4| which in turn produces a corresponding translation of the main valve shuttle I4. When this occurs the head I8 changes sides and occupies the left side of the pump discharge port 2|. Flow is then from the main pump 22 through the outlet port 26 and the line 24 back into the pressureA tank 49. Simultaneously the QQndult His connected through the port I2 and an outlet "port 18 in the body oi the main valve I3 so that oil flows from the cylinder 6 through the main valve cody and port 18 and through a conduit 19 to the pump inlet conduit 29 for return to the balancing tank 49.

Asl the piston 1 descends,y the space above it is substantially at atmospheric pressure, This $01,3-

dition persists until the piston 1 has lowered sufciently to uncover a control line 8| having a suitable check 82 therein and communicating with the line 38. When the line 38 is thus exposed to atmospheric pressure, ow to relieve the pressure in the line 38 takes place through the check 82. The pressure exerted on the head 43 is thus dropped approximately to atmospheric. The pressure on the smaller head 46 is still considerably above atmospheric. as the head is exposed through the connection 48 with the balancing tank pressure. The unbalanced pressure shifts the pilot shuttle 4I back into the position shown in the iigure. Consequently flow from the scavenge pump 59 goes through the port 61 and through the pilot valve body 39 to discharge from the port 14 through the line 13 into the body of the main valve I3. The head I1 is thus exposed to the scavenge pump pressure While at the same time the pressure on the opposite head I9 or the main valve is reduced approximately to atmospheric. This is because pressure com` munication is through the port 1I and the line 69 and the ports 68 and 54 in the pilot valve with the discharge line 56 leading to the sump 53. The described cycle is repeated indefinitely un der control by the motion of the piston 1 within the cylinder 6 in turn affecting the motion of the shuttle 4I. This in turn aifects the operation of the main valve I3, itself controlling the supply of oil from the balancing tank 49 to the cylinder 6- and the return of oil from the cylinder to the balancing tank.

During operation it is one of the functions ofl the scavenging pump 59 to return excess oil to the balancingtank 23 and to maintain a suitable level of oil for operation within the sump 53. For this reason substantially all of the leak age or drainage oil is led back to the sump 53 butthat may not be suiiicient to provide adequate oil for the sump. A make-up means is provided.

When the pilot shuttle 4I is translated to the-- opposite position from that illustrated in the gure, the scavenging pump discharges through its conduit 58 and the port 61 and then through the port 68 and the conduit 69 into the body of the main valve I 3. If the main valve is displaced from the position shown in the gure, oil ows from the port 1I through the end'chamber i the body to an outlet port 83 leading into aV line 84. This line leads to a valve -86 controlled by a iioat 81 responsive to thev level of oil in the sump 53 and governing dow through a pipe 88 into the sump. If the sump level is low the scavenge pump is effective locally to circulate oil and to pump it back into the sump 53. When there has been suiiicient leakage and the sump level is correspondingly high, the valve 86 is closed and uid in the conduit 84 then flows through a branch pipe 89 leading through a check 9| into the balancing tank 23 which also serves as a reservoir.

In accordance with my invention the fluiddis charged by the scavenge pump is utilized to actu.- ate a means for `supplying make up air tothe.- When the pilot. valves in.

balancing tank 23. the position shown in the gure, the scavenge "two paths. It can proceed through a port l94 connected by a conduit 96 to a valve 91.' This .valve is normally closedgby a spring 98 yet is opened upon the occurrence of an excessive pressure or one higher than a predetermined pressure to permit the passage of oil throughvthe valve and through a, duct 99 back into the sump 53. The pressure at which the valve 91 .opens is less than that at which the relief 63 opens. If therefore the pressure of the oil in the line 13 or its connections is excessive when the main valve is translated as shown, the excess oil can travel through the conduit 96 and by opening the valve 91 can escape to atmospheric pressure through the conduit 99 into the sump 53. When the 'pressure is below a set or predetermined value, this avenue of egress is closed by the valve 91' and only the alternative path can be utilized. The amount of flow through the alternative path is small and is more in the nature of a pulse.

The alternative path includes a port |0I leading from the main valve body I3 through a conduit |02 merging with a pipe |03 adjacent the check valve 93. The conduit |03 extends to an air compressor |04. The structure of this air compressor can be varied to suit individual circumstances, but in the present instance it comprises a main cylinder body |06 within which is disposed a reciprocable plunger |01 having an enlarged piston |00 thereon exposed to the pressure of oil entering through the conduit |03. Likewise included in the plunger is a reduced diameter portion |09 designed to reciprocate within a reduced cylinder III. Between the enlarged and the reduced cylinder portions there is formed a variable chamber |I2, connected by a pipe ||3 to the air space I I4 within the balancing tank 23. When the pressure within the chamber |06 is in excess of the resultant pressure on the other side of the head |08, plus the pressure on the plunger |09, the plunger is translated upwardly as seen in the iigure. When the pressure within the chamber |06 is low, tank pressure within the chamber I I2 is eifective to translate the plunger downwardly as seen in the figure. The extension |09 serves as an air pump. In its lowermost position it uncovers an air port |I6 communicating through a duct |I1 and a check valve |I8 to the atmosphere. The cylinder II I is provided with a check valve I9 controlling flow from the cylinder through a duct |2| into the air space II 4.

Fluid under pressure from the scavenge pump 59 flows through the pipe 13 and the pipe |02 into the conduit |03 and lifts the plunger piston |08. The rising piston cuts off the port ||6 thus trapping a body of air and during its further motion compresses the trapped air sufficiently to unseat the outlet check II9 and to displace the air into the chamber I I4. This position of the plunger is maintained until such time as the main valve shuttle I4 is translated to the opposite extreme position from that shown in the figure and has cut off the port IOI. The shift of the shuttle I4 is caused by a shift of the pilot valve shuttle 4| connecting the port 14 with the port 16.- Since the'latter is connected by the conduit 52 to the atmospheric pressure sump 63, the pressure Within the conduit 13 likewise drops substantially to atmospheric. Under these circumstances the intermediate pressure from the chamber II4 is exerted to close the check valve I I9 and is effective upon the. differential area between the head `|08 and the portion |09 to force the plunger |01 downwardly. This motion discharges the oil previously contained in the cylinder |06 through the conduit |03 and past the check valve 93 into the connecting pipe 92 and so into the conduit 13 and finally back to the sump. Having returned to its" lowermost position, the air pump plunger |01 de--` riving its power from the scavenging pump 53 is set for a repetition of the cycle of operation in response to the operation of the main valve |3 and oi the pilot valve. The pressure of the air in the chamber I I4 is regulated by the pressure at which the valve 91 is forced open by the actuating liquid.

I have thus provided in accordance With my invention in a hydraulic jack system including a main cylinder, a balancing tank, a main valve and a scavenging pump, a means for supplying make up air to the balancing tank, the make up' air supply means being governed and actuated by the scavenge fluid and the pressure of the air being regulated in accordance with any set or desired value. The structure of the air pump is a type which can be readily incorporated with previously existipg hydraulic jacks since it relies upon a hydraulic drive readily provided by the installation of appropriate conduits and pipes. There is afforded by my invention an improved airsupply for a hydraulic pumping jack mechanism.

I claim:

1. In a hydraulic jack having a balancing tank for containing air and oil, a main pump, a control valve for governing oil now to and from said tank through said main pump, and a scavenge pump for periodically discharging oil into said tank under control of said valve, the combination of an air compressor cylinder communicating with the atmosphere and with said tank, check valves for said cylinder, a plunger in said cylinder, and means responsive to the operation.

of said control valve for alternately subjecting an actuating surface of said plunger to the pressure of oil discharged by said scavenge pump and to atmospheric pressure.

2. In a hydraulic jack having a balancing tank for containing air and oil, a main pump, a control valve for governing oil flow to and from said tank through said main pump, and a scavenge pump for discharging oil into said tank under control of said valve, the combination of an air compressor communicating with the atmosphere and with said tank, means for utilizing oil discharged from said scavenge pump to drive said compressor, and means responsive to the operation of said control valve for controlling said utilizing means.

3. In a hydraulic jack having a balancing tank for containing air and oil, a main pump, acontrol valve for governing oil flow to and from said tank through said main pump, and a scavenge pump for discharging oil into said tank under control of said valve, the. combination of an air compressor discharging into said tank, means including said scavenge pump for driving said air compressor, and-means responsive to the operation of said control valve for controlling said driving means.

4. In a hydraulic ,jack having a balancing tank for containing air and oil, a main pump, a main control valve for governing oil flow to and from said tank through said main pump, and a pilot valve for operating said main valve, the combination of an air compressor discharging into said tank, a secondary pump for driving said air compressor, and means responsive to the operation of said pilot valve for controlling the driving of said compressor by said secondary pump.

5. `lin-.a hydraulic `lack having a balancing tank for containing air and oil, a control valve for governing -oil flow to and from said tank, and 'a scavenge pump for discharging oil into said tank under control of said valve, the combination of an air compressor for supplying air to said tank, means for utilizing oil discharged from said scav enge pump to drive said compressor, means responsive to the operation of said control valve for controlling said utilizing means, andnieans responsive to the pressure of oil discharged from said scavenge pump in excess of a predetermined value for rendering said supplying means inoperative. 6. In a hydraulic jack having a balancing tank for containing air and oil, an atmospheric pressure #anhand a scavenge pump `for dischargingoil from said atmospheric pressure tank into said balancing tank, the combination of an `air compressor for supplying air to said balancing tank, means for utilizing oil discharged from said scavenge pump to drive said compressor, and means responsive to the pressure of said discharged oil in excess of a predetermined value for renderli?,F said supplying means inoperative.

7. In a hydraulic jack having a cylinder with a port therein, a piston reciprocable in said cylinder to cover and uncover said port, a balancing tank foi-.containing air and oil, a main pump, a control valve connected to said port for governing oil iiow to and from said cylinder and to and from said tank through said main pump, and a scavenge pump for discharging oil into said tank under-control of Said valve, the combination .of an air compressor discharging into said tank. means including said scavenge pump for driving said air compressor, and means responsive to the operation of said control valve vfor controlling said driving means,

8. In a hydraulic jack having a cylinder with a port therein, a piston reciprocable in said cylinder to cover and uncover said port, a balancing tank for containing air and oil, a main pump, a main control valve lfor governing oil flow to and from'said cylinder and, to and from said tank through said main pump, and a pilot valve con nected to said port for operating said main valve, thecombination of an air compressor discharge ing rinto said tank, a secondary pump for .drin ing said air compressor. and means responsive to the operation of said pilot valve for controlling the driving of said compressor by said secondary pump.

IRA MORGAN WHITE.

REFERENCES CITED The following references are of record in the le of this patent:

UNITED STATES PATENTS Number Name Date 1,879,262 Hubbard Sept. 27, 1932 1,941,766 Thom Jan. 2 193i 2,157,219 Salentino May 9, 1939 2,343,302` Twyman Apr. 25, 1944 2,414,979 Ross Jan. 28, 1941

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