US2575241A - Hydraulic pumping jack - Google Patents

Description

Nov. 13, 1951 I. M. WHITE I 2,575,241

HYDRAULIC PUMPING JACK Filed Sept. 6. 1949 a Sheets-Sheet 1 I 59 J 3 \96 n 37 F-lEi "L Nov. 13, 1951- I. M. WHITE 2,575,241

HYDRAULIC PUMPING JACK Filed Sept. 6. 1949 5 Sheerls-Sheet 2 INVENTOR. 1 c7 Marga/7' W/w/a Nev. 13, 1951 l. M. WHITE 2,575,241

HYDRAULIC PUMPING JACK I 3 Sheets-Shea; 5

Filed Sept. 6. 1949 III , INVENTOR. //*0 Marga/7 W/w/a Patented Nov. 13, 1951 HYDRAULIC PUMPING JACK Ira Morgan White, Berkeley, Calif., assignor to The Pelton Water Wheel Company, San Francisco, Calif., a corporation of California Application September 6, 1949, Serial No. 114,180

at the bottom of deep oil wells and to similar structures in comparable environments. Pumping jacks hydraulically actuated have become increasingly popular in recent years and one of the characteristics of most of them is the provision of a cylinder and piston combination hydraulically reciprocated at thesurface to operate the oil pump at the well bottom. A prime mover opcrates a main pump for furnishing working oil to the jack to reciprocate the piston in the cylinder. In order to balance part of the load on the piston there is usually provided a balancing tank containing oil and air under an intermediate pressure. The mechanism, like most hydraulic structures, is subject to more or less leakage from time to time particularly after it gets old in use. Some of the operating instrumentalities suchas valves and the like, are power actuated by oil and as a consequence actuating oil is from time to time released from the high pressure part of the system. It is customary to provide some sort of means for returning this released oil and leakage oil to the balancing tank and it is also customary to provide some way for maintaining the desired pressure on the balancing tank usually by regulating the air pressure. While various structures for this purpose have been utilized in the past, it is a general object of my invention to improve upon previously known devices.

Another object of my invention is to provide a pumping jack mechanism in which the oil return or scavenge pump is effective over a long period of time, that is, has a long practical life.

Another object of my invention is to provide a pumping jack mechanism in which the supply of air to the balancing tank is established at the strain on the hydraulic system.

A further object of my invention is to provide 2 a pumping jack mechanism in which the relative quantities of oil and air returned to the system are variable over wide limits.

A still further object of my invention is to provide in a pumping jack mechanism a scavenge pump structure capable of lon and satisfactory use under overload conditions and without serious danger of'overl eating orexcessive wear.

A still further object of my invention is in general to improve pumping jacks.

Other objects of the invention together with the foregoing are attained in the embodiment of the invention illustrated in the accompanying drawin s, in which:

Figure 1 is a schematic layout showing a pumping jack mechanism constructed in accordance with my invention. While the present showing is diagrammatic some of the parts are illustrated approximately as they appear in practice.

Figure 2 is a cross section on a longitudinal, axial plane of a scavenge pump constructed in accordance with my invention for incorporation with the pumping jack mechanism.

Figure 3 is a cross section on a transverse vertical plane through the structure shown in Figure 2.

Figure 4 is a fragmentary cross section to the same scale as Figure 2, the plane of section being on the line 4-4 of Figure 2.

While my pumping jack mechanism is susceptible to incorporation or embodiment in a number of different ways and is satisfactorily utilized in a number of different environments or fields it has been particularly successful in connection with a pumping jack of the type shown in my pending application Serial No. 32,629, filed June 12, 1948 and entitled Hydraulic Pumping Jack Control and also as shown in the patent of Kyle and White 2,325,138 issued July 27, 1943. In such environment the embodiment of the invention attains most of its advantages.

In its preferred form the pumping jack mechanism of my invention includes a jack cylinder in which the jack piston is reciprocable, being operated by the transfer of oil between the cylinder and a balancing tank containing oil and air. In order to restore leakage and process or utility oil to the balancing tank and to keep the tank supplied with air, a positive displacement piston pump serves as a scavenge pump and takes air and oil or mixtures of air and oil and restores them to the balancing tank.

In the particular embodiment chosen for illustration, there is provided a jack piston S normally operated in a vertical direction along the axis of a piston rod 1 extending to the bottom of a well and actuating a pump there disposed. The piston 6 is reciprocable within a jack cylinder 8 suitably mounted and provided with a closure plate 9 at its upper end. A supply of actuating oil is disposed in a body H in the lower part of a balancing tank l2 appropriately located, the upper part of the tank containing a volume 13 -23. the pressure within the line 27 and in turn coni the pipe is and the cylinder 3 3 of air under the same pressure as the oil. Oil from the body H is Withdrawn through a duct l4 into a reversing valve 16 and then passes through a force pump ll driven by an electric motor 18 or other suitable prime mover.

The pump il discharges the working oil from the reversing valve [5 through a line l9 into the lower end of the cylinder B beneath the piston 6. This has the effect of lifting the piston. As soon as the piston uncovers one of a series of top stroke selector ports 2! the normally atmospheric or substantially atmospheric pressure on the port when it is above the piston 6 is suddenly increased because the port is then exposed to the pressure of the operating fluid beneath'the piston 6. I This pressure is transmitted to a line??? and through a selector valve 23 to a main line 24. :Thev-alve 23 renders any desired one of the ports 21 effective and excludes the others so that the upper'limitof the piston stroke is set by the positioning of the Q selector valve 23.

Pressure transmitted through the line 25 passes a check valve 26 and is imposed upon a conduit This leads to a pilot valve 28 responsive to trolling the reversing valve HS. W hen such valve is actuated, the effect of the main pump I! is no longer to transfer oil from the body H through but rather is to withdraw the oil from the cylinder 8 through the pipe l9 and to pass it through the pump H and back through the line' [4 into the body ll within the tank I2. In thiswa-y the piston 6 is permitted to descend into the cylinder 8 until such time as the pressure which normally has been exerted on the effective one of aseries of lower stroke limiting ports 29 is released. This occurs as the piston passes such port and subjects it to atmospheric pressure rather than to line pressure. The effect is felt through a connector 3| extending from the various ports 29 through a check valve 32 to the conduit 2'1. Thus, when the piston 6 lowers to a selected low point, the-pilot valve 28 is affected, the reversing valve I6 is again changed and oil is no longer pumped from the tank !2 backinto the cylinder 8 beneath the piston.

This is the customary cycle of operation of the hydraulic pumping'jack. As an incident to such operation, the oiltransferring mechanism, particularlythe pilot valve 28 and the reversing valve it, releases some of the pressure fluid normally within the conduit [4 from the pressure system. This "released all loses its pressure promptly and is discharged through a drain or scavenge line 33 to a sump line 34 at a low point in the system.

As an incident to'the operation of the piston 6 within the cylinder 8 and since no hydraulic mechanism is entirely tight over a long period of time, some fluid or oil leaks from beneath the a piston to a position above the piston at a much lower pressure. This leakage oil at the uppermost'part of the stroke is'forced or spilled from the cylinder 8 through ports 36 and enters a surrounding. closed housing 3'! and passes from such housing into a conduit 38 extending to the sump pipe 3c. The substantially closed upper end of the cylinder is made to serve as a preliminary-cr booster air pump chamber. It is supplied with air at approximately atmospheric *pressure through a port 39 in the wall of the housing 31. As the piston 6 lowers and increases I the volume of the space above it, air is drawn tank I2 I provide in accordance With my invention a'special scavenge" pump 4|. This pump is illustrated diagrammatically in Figure 1 and as actually embodied in Figures 2, 3 and 4. The pump is preferably mounted to be driven by the motor [8 and includes a mounting bracket 42 removably'fastenedon one end of the housing I? Q 'of-the pump. The shaft of the motor l8 passes through'the pump housing and a section 43 of such shaft'passes through the mounting bracket 42 and extends into the crank case 44 of the "pump. The crank case has a lower, removable cover 46 but in operation is closed to the atmosphere; It is provided with a: boss 47 into'which the sump pipe 34 is connected by .aninletpipe 48. Fluid from the various drain and scavenge lines and air from the line 38 thus can flow freely into the interior of the pump crank case.

. Withinthc crank case the extension shaft l3 is provided with a pinion gear 5i transmitting i the present instance two stages, andit is also of its rotary motionto a ring gear 52 centrally. discentral gear .52

The scavenge pump is preferably a positive displacement piston pump of several stages, in

the valved variety. For that reason Imounton the crank case-44a cylinder block 63 fastened thereto by suitable securing devices 64. The

block incorporates a first stage cylinder 66, sometimes called a low pressurecylinder, and asecond stage or high pressure cylinder 61. Adapted to operate in the cylinder 66 is a low-pressure or first stage piston 68 connected .to the eccentric 6! by a connecting rod. 69.

Similarly, in the second stage cylinder 61 a piston II is joined to the eccentric -62 by aconnecting rod 12.

16 .in a detachable cylinder head 11.

scendsytheresulting vacuum opens the valve 18 permitting fluid to flow from the crank case 44 through the passages '13 and T4 and the passage '76 into the interior of the cylinder 66.

Material in the cylinder is expelled from the cylinder as the piston 68 rises by flowing through an outlet poppet valve 82 shown in Figure 2. This valve is normally urged toward its seat by a'spring 83 and controls flow from the cylinder 66 through a-passageway -84 to an inlet valve 86 leading to the'cylinder 61, The valve -86'is also pipe 93 to the tank I2.

of the poppet type and is usually held seated by a spring 87.

Material drawn into the cylinder 6'! through the opening provided when the 'valve 86 is unseated is subsequently expelled from that cylinder through a port 88 controlled by a valve 89 pressed on its seat by a spring 9| and giving access to a passageway 92. An outlet conduit 93 extends from the opening 92 to a suitable point of entry 94 into the tank l2.

In general, fluid flows from the pipe 33 and the conduit 38 into the sump pipe 34 then into the crank case 44 of the scavenge pump, then into the first stage cylinder 66 of such pump then to the second stage cylinder 61 of the scavenge pump and finally through the outlet In accordance with my invention, I provide means for supplying makeup air along with the scavenge oil and for affording preliminary compression of the makeup air even before it gets to the first stage of the scavenge pump. The chamber 31 around the main cylinder 8 is especially provided with an air inlet check valve 96. In actual operation,

. atmospheric air is drawn in to the cylinder 8 during the descent of the piston 8 the weight or head of the fluid in the long vertical pipe 38 being sufiicient to prevent substantial back flow or a check valve 9! precludes backfiow.

During the subsequent ascent of the piston 6 the valve 9% closes and the then trapped air is expelled through the passages 36 and through the pipe 38 toward the scavenge pump 4!. Leakage oil from the cylinder 8 also travels through the pipe 39 to the scavenge pump, in the sump pipe 94 joining released and leakage oil coming through the duct 33. There is consequently supplied to the crank case 44 of the scavenge pump both noncompressible oil and compressible air and in various mixed amounts and relative quantities at random. That is, there may be a very large .amount of oil arriving at the scavenge pump one particular moment, a very small amount at a following moment and perhaps a moderate intermixture at other times.

This mixtureof air and oil, air individually or oil alone is retained partly in the crank case 44 at least no higher than the entrance level of the conduit I3. If the oil tends to go much higher than that it is readily drawn into the conduit 73 whereas if the level sinks well below the inlet to the conduit I3 its induction to the remaining part of the scavenge pump is not readily accomplished. There is consequently an automatic oil level regulation at a point sufliciently high to lubricate the gears and revolving parts of the pump and at a point to provide ready induction to the cylinders of the pumping mechanism.

The fluid flowing into the first stage cylinder 68 is expelled from that cylinder under varying conditions. If air alone is involved, the air is compressed to an amount dependent upon the resistance to flow partly regulated by the spring 83 incorporated with the outlet valve 82. The air so compressed is then transferred to the smaller volume second stage cylinder El, is again compressed in that cylinder and is restored to the balancing tank I2 at a pressure equivalent to the pressure inside that tank. If air so pumped tends to increase the pressure in the balancing tank (both as to air and oil) above the desired amount, the excess air is bled off or permitted to escape through a regulating valve I92 blowing to the atmosphere and adjustable to the precise pressure desired.

If, instead of air, oil alone enters the scavenge I pump cylinder 66; the oil when expelled would travel into the volumetrically smaller second stage cylinder 61. The first stage volume will not fit the smaller volume of the second stage cylinder. It is possible, by permitting the loads on the piston I58 to run up quite high, to force the solid oil entirely through the outlet valve 82, through the passage 84, through the inlet valve 36 and through the outlet valve 89 to the outlet conduit 93. The pressure on the oil at the first stage therefore becomes substantially that within the balancing tank I2. It is preferred not to permit the pressure on piston 58 to run up to that extent. As shown in Figure 4, I provide a special relief valve I93 urged into a port I 34 in the cylinder 66 by a closure spring I96. The port i534 opensinto the passageway 16 in communication with the interior of the crank case 44. Depending upon the setting of the spring I95, when the piston 68 ascends liquid leaves the cylinder 66 through the valve 82 or if the pressure is great through the relief valve I93 also.

Sufficient oil to charge fully the cylinder 67 travels through the passage 84 whereas the excess represented by the greater size of cylinder 66 is bypassed through the passage 78 back to the interior of the crank case 4d. In this way the maximum pressure on the piston 68 is limited. While the operation has been described with oil, air too, can by-pass if for any reason the pressure becomes high enoughto open the relief valve. According to this arrangement the maximum quantity of oil alone that can be pumped is regulated by the volume of the second stage cylinder 6'! whereas the maximum amount of air that can be pumped is dependent upon the volume of the first stage cylinder 6B. This relationship is maintained at about the expected ratio for operation of the balancing tank I2.

Preferably the ratio between the pinion BI and the ring gear 52 is such with regard to the speed of the motor I8 and the main pump I! that the scavenge pump 4! operates at a relatively slow rate. This is primarily for the reason that the oil and air mixture most often pumped may possibly be of an explosive character if its temperature is high. While oil alone in the absence of air will not explode and air alone in the absence of oil is not combustible, still an oil-air mixture in proper proportions will burn if it is sufiiciently hot. By operating the scavenge pump at a relatively slow rate (in one instance 75 R. P. M.) the temperature rise due to pumping and compression of air and displacement of oil is relatively'slight, the heat dissipation from the pump alone being suflicient to keep the temperature well within a safe margin.

Very seldom does the scavenge pump pump oil alone. Most of the time it operates on a mixture so that there is some compressibility and some cushioning effect to alleviate what otherwise might be a water hammer symptom in the hydraulic piping. Furthermore the pumping of oil with the air through the entire scavenge pump is effective to lubricate all of the parts even those without substantial lubrication if air alone were pumped. It has been found in practice that a scavenge pump of this sort has a life many times that of an oil pump operating alone or of an air pump operating alone so that by combining both fluids and handling them in one positive displacement multi-stage pump considerable improvement has been made.

The volume of oil in the system is substantially constant and little or no oil is lost from the system as a whole during normal operation. It is not necessary inthis environment to provide any lag-575,241

oil make up'valve or any oil release rvalveiif fluctuations in oil volume dueuto .changes in temperature (both seasonal and due .to operationtof the mechanismi can be compensated for. These are absorbed .by changes .in volume of .the -air body 13 in the .balancingltank. .The air system is operated with a variable volumeand so provides compensation for the. slight fluctuations in the. oil system. That is, when the pressure .gets too high rather than bleed oil.from.the system,

/ extra air is let out from the relief valve 102. When the pressure .gets.1ow .thesreliei valve [.02 it closes until suiiicient airhas been added. through the inlet valve 96.

enters thetvalve .96 is approximately constant The quantity. of air which for any given jack stroke because the speed of operation of .themain jack piston 6 and of the scavenge pump 4! is always substantially constant. This quantityis sufiicientlygreat so that by varying the amount of air bled ofior released through the valve 802, the pressure within the balancing tank 12 both onthe oil body II and the air volume 43 is maintainedat the selected value.

It is to bee-specially understood that the show-- ingherein although representative of a practical embodiment is especially in Figure 1, a diagrammatic showing intended to illustrate the most pertinent features of the scavenge 'pump ar- .rangement. The conduit 33 for example, is intended to represent various conduits normally present and which supply oil to the sump line-34 and theline 33 is intended to represent numerous .linesin practice carrying leakage oil. Furthermore, the pilot .valve.28, reversing valve l6, and

andsaid cylinder to reciprocate said piston,isornev of saidoil escaping .fromsaid transferring mechanism, a pump adapted to pump an air and .oil

mixture, aconductor. for conducting said'escaped oil from said cylinder to said'pump, a. port .com- U municating with the atmosphereior admitting air tosaid conductor, and a conduit for conducting oil and air discharged by said pump to'said balancing tank.

2. A hydraulic pumping jack comprising a jack cylinder, a jack .pistonireciprocable in said cylinder, abalancingtank for containing oil and air,

mechanism for transferring oil between said cylinder andsaidtank to reciprocate-said piston, some ofsaid oil leaking past said piston, apump having an inlet-communicating with the atmosphere and-an outlet, a conduit connecting said pump outlet and said balancing tank, and a connector for conducting said leakage-oil to said pump to be forced with said air into said balancing tank.

3. A hydraulic pumping jack comprising a jack cylinder, a jack piston reciprocable insaidcylinder, a. balancing tankfor containing oil and air, mechanism having oil releasing openings for transferring oil between said tank and saidcylin- .wdeixto reciprocate said .piston,.someuof said oil being releasedirom said-.itransferring mechanism through said: releasing openings, a pump .having an inlet'com-municatingwith the atmosphere and l8 .Ejan ut1et,la conduit cconnectingssaidi pumpi-outlet and. said floalancing: tank, lan'd .a connector ".for conducting: said-:released oil to said; pump tocbe :forced:withlsaidiairintosaidhalancing tank.

l 4.;A; hydra1flic pumpingiiackicomprising aja'ck cylinder; :a;g'ack-:piston reciprocable in. said lcylindrier, a balancingltank ior containing oil and. air, .;:mechanism:for-:transferring .oil.between said tank and .sai'dtcylinder: tol'reciprocate. said. piston; some a m .;of.' saidcoil leakingzpast saidlpiston and: some of ssaid..-;oil being releasedufrom csaid :;.transferring :mechanism, .azpumphavingan inlet communicatringcwithithe atmosphere. andhaving .:an outlet ::.communicating .with :said balancing: tank, and 5: connector :iorxconducting .esaid leakage. .oil- :and said:released:;oil:.to said. pumpitozbe formed with said: airintoisai-d balancing tank.

.1 5.-.A hydraulicpumpi-ng .jacktcomprising. a jack -:cy inder,. a. jack .piston';reciprocable: in said cylgnzindenea balancing. tankvforv containing oil and .air, mechanism fortransferring oiluhetween said :tankzandesaid'cylinder. to reciprocate said pis- .ston; apumphaving an inlet and an outlet, a con- :duitioriconnecting said outlet to said tank,'anda kconnector communicating withzthe atmosphere .andwithsaid tran'sferringmechanism for con- '.:ducting to ;said inlet. .both 'oil; fromsaid :transierringmechanism rand air.

6.. A hydraulic pumping jack comprising a n jack cylinder, a jack pistonreciprocable in said cylinder, a balancing tank for containing oil and air, mechanism for transferring oil betweensaid tank and said cylinder to reciprocate said piston, a positive displacement pump having an outlet connected tosaid tank and having an inlet, and a'connector communicating with the atmosphere I and with said transferring'mechanism forconducting to said inlet both oil from said transferring" mechanism and air. n 7. A hydraulic pumping .jack comprising a jack cylinder, a balancing tank for containing oil and air, a hydraulic system for transferring oil under a relatively high pressure between said tank and said cylinder, ascavenger system, some 3 of said oil being released from a relatively high pressure in said hydraulic system to a relatively low pressure in said scavenger system, and a single pump communicating with the atmoslphere and with said scavenger system for forcingsaid oil fromsaid scavenger system and air into said balancing tank.

8. A hydraulic pumping jack comprising a jack cylinderclosed at its upper end, a jack piston .reciprocable in saidcylinder, a balancing tank for containing oil and air, mechanism for transferring oil betweensaid tankand said cylinder below said piston to reciprocate said piston, some of said oh leaking past said piston, a check- .valvedair inlet to said cylinder abovesaid piston, a valvedpump havingan inlet and an outlet, a connectonextending from said cylinder above said pistonato'said inlet, and a conduit extending from said pump. to said balancing tank.

9. A hydraulic pumping jack comprising a jack cylinder, a jack piston reciprocable in said cylinder, a balancing tank for containing oil and vair,.mechanism for transferring oil'between said tank and said'cylinder to reciprocate said piston, and a single pump communicating with the atmosphere and with said transferring mechanism for simultaneously supplying said balancing tank with oil and air.

10. Ahydraulie pumping jack comprising a jack cylinder, a jack piston reciprocablein: said cylinder, .abalancing' tank for containing oil and air, a main pumping mechanism for transferring oil between said tank and said cylinder to reciprocate said piston, and a secondar pumping mechanism communicating with the atmosphere and with said main pumping mechanism for simultaneously supplying said balancing tank with oil and air.

11. In a pumping jack mechanism having a balancing tank for containing a body of oil and air, a positive displacement pump having an inlet and an outlet, a conduit for connecting said outlet to said tank, and a connector communicating with the atmosphere and with said body of oil for supplying both oil and air to said inlet.

12. In a pumping jack mechanism having a balancing tank for containing a body of oil and air, a multi-sta e piston pump having an inlet and an outlet, a conduit for connecting said outlet to said tank, and a connector communicating with the atmosphere and with said body of oil for concurrently supplying both non-compressible oil and compressible air to said inlet.

13. In a pumping jack mechanism having a balancing tank for containing a body of oil and air, a multi-stage piston pump having an inlet and an outlet, a pressure conduit connecting said 10 outlet to said tank, a connector communicating with the atmosphere and with said body of oil for supplying said inlet with air and oil, and a fluid pressure responsive by-pass connected between successive stages of said pump and said inlet.

14. In a pumping jack mechanism having a balancing tank for containing a body of oil and air, a pump having cylinders and pistons of different sizes, a connector communicating with the atmosphere and with said body of oil and then connected to one of said cylinders then to another of said cylinders and then to said tank, and a valved conduit joined to said connector between said cylinders for releasin fluid from said connector between said cylinders.

IRA MORGAN WHITE.

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

UNITED STATES PATENTS Number Name Date 2,325,138 Kyle et al July 27, 1943 2,363,142 Reed Nov. 21, 1944 2,481,623 Rued Sept. 13, 1949

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