US2555426A - Hydraulically actuated pumping system for wells - Google Patents

Description

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ATTORNEY 2 Sheets-Sheet 1 June 5, 1951 w. c. TRAUTMAN ETAL HYDRAULICALLY ACTUATED PUMPING SYSTEM FOR WELLS Filed Sept. 24, 1945 m T S u L MO H m 2 WE Y B T r lfl ldw J lv lJ 0A 5 42/ l 1951 I 7w. c. TRAU-TMAN ETAL 2,555,426

HYDRAULICALLY ACTUATED PUMPING SYSTEM FOR WELLS 2 Sheets-Sheet 2 Filed Sept. 24, 1945 llllllllllltlllla I!!! IIIIIII IIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIII \lllllUl.ll.l\lll\ll"lllllllllllllllllllIlllUH-lllllllllllllllllllllll L w, I "\ib 'IIJIIIIIIIIIIIIUIIIIIIIIIIIIllnlllll'lllllllmll lllllllllllln Ill 2 \I[III/11111111111111!rill/111111111111n' INVENTOR. W. C. TRAUTMAN BY EZRA HOLLISTER ATTORNEY Patented June 5 1951 'HYDRAULIOAIJLY ACTUATED PUMPING SYSTEM FOR, WELLS Walter C; 'lrautman, Los Angeles, manna" H61 lister; Temple City, Calif., assignorsitdBendix Aviation Corporation, SouthBend; Ind, aizor poratioii ofDelaware Application September 24;=1945, Serial Norma-184 6 Claims.

' 'This invention relates-t0 hydraulic-actuation 1 of in-the-well pumps and is particularly useful "-for the :actuation-ofrzp'umps in relatively deep wells, such as many :oil wells, in which a pump rat a substantial depth in the well is reciprooated from the surface'ithrough a sucker rod-which may have substantial stretch because of its length.

A broad object ofwthe invention is to increase the efficiency oi -an in-the-well pump actuated through a longsucker rod, by applying substantially constant force to the sucker rod throughout its stroke irrespective of variations in the velocity of the upper end of the sucker rod at -different positions within itsstroke.

Another object is to provide a-power unit for reciprocating"the-sucker rod of anin-the-well pump, which unit is compact-and self-contained and can be readilymoved between an operative "position-in which it isco-nnected to the sucker rod and an inactive position in Which'it is clear 0f the well to' per-mit various operations; such as pumngahe pu-mpoutof the well and cleaning the well etc.

A-nother object is toprovide a hydr'aulic actuating mechanism for an-in-the-Well pump, in "whichthe sucker rod of the pump is directly actuated by fluid at a relatively low, safe pressure supplied' by alarge volume,-low pressure, pump which, inturn=,- is di-rectlyactuated by a relatively compact hydraulic motor supplied by a relatively low 'volume;- high pressure pump.

Anotherobject is to provide "a -practicable and 4 reliable system for--app1ying substantially uniform force to the -upper end" of the sucker rod of an in-the-well pump throughout the pumping stroke of the sucker rod.

Another object is to provide apracticable valve mechanism for con'trolling flow of chigh pressure fiactuating liquid to a reciprocating hydraulic motor insuch a way as to eiiect smooth reversal of the motor at opposite ends of its stroke.

Another object is to provide a hydraulic pumping mechanism'for reciprocating the sucker rod of an in-the-well pump which is substantially 'fully automatic andself-adjusting'to compensate for unavoidable fluid leakage in" the system.

Other more specific objects and features of-the invention will appear from the detailed description to follow ofone specific embodiment of the invention.

It has been-common"practice'formany years to-reciprocate the plunger or piston of an in-the- 1 well pump through a sucker rod extending "from --the pump to thesurface -and connected at the visurfaceto a rotating crank througha connectingrod or the equivalnt' so that,inresponseto "up er end of the 'st'rokel The" maximum'rate' at which the sucker "rod"'cou1dbe 'recip'rocatedby str'ess appliefcl'tothe rod at some particular "pcinrm 'the stroke; Which 'stre'ssWvas uscauy muchfg'reater thanfthe veragestress throughout the'up'per end of "the sucker rod 'sho'uldbe moved ".at such aratethroughoutits-strokethat -the stress is substantially constantandof substan- "tiallythe'same' magnitude asthemaximum stress which it is safe to apply to the rodf Unfortu- V 'n'a'tely, it is impossible tobbtainthisTesult with mechanismswhich reciprocate the upper end of the sucker rod'in accordance with some predeter- "minedrate of movementjbecause of factors such as the "inertia and stretch; which "are unavoidable and" the "effects"of'vvhich'are difiicult to compute in a="longsucker rod. It is essential,

therefore, in order toatta'in a high pumping'efii- "ciencyl to'em'ploy a mechanism that 'willapply substantially c'onstantioiceto-the sucker rod andiet-theacceleration and deceleration of the rod be determined by the resistance it ofiers to movement, which resistance "varies unpredictably over wide limits because of thestretch-and inertia of the'rod.

In accordance Withthprsehtinvention we "are able to apply a"substantiallyconstant force "'"tothe upper endof a" sucker rod by directly connecting the sucker rod to a 'hydraulicjack of relativelylarge-effective diameterg which isactu- *ated to lift the sucker =ro'd by admittin pressure fluid -to the jack and-Q to" lower the sr icker rod by releasing pressure fi uid tram the jack. The

pressure fluid is supplied by a" reciprocating pump --wh ich is "directly connected to the jack; and the pump in turn is recip'roe'ated by a reciprocating hydr aulic 'motor directly connectedfithereto and 1 fluid at substantiallyficonstantpressure which is applied without restriction to the reciprocal motor during themain portions of the strokes of the latter, but is throttled vnear the end of each stroke to rapidly "but smoothly clecelerate sure.

the motor. Hence, during the major portion of the stroke a substantially constant force is .applied to the reciprocating pump, which delivers pressure liquid to the jack. To enable the jack to move at varying velocity in diiferent parts of each stroke, according to the resistance afforded to its movement by the sucker rod, a relatively large hydraulic accumulator is connected in parallel with the jack to supply additional pressure fluid to the jack when it tends to move rapidly,'

and to absorb excess fluid delivered by the reciprocating pump whenthe resistance of the sucker 7 amount of power. In accordance with the present invention the hydraulic jack and the reciprocating pump, which directly supplies fluid to actuate the jack, are of relatively large diameter and are positioned close together, so that they can be economically interconnected by large diameter conduits, thereby enabling the use of fluid at relatively low operating pressures in that part of the system in which compressed gas is (in the accumulator) to equalize the pres- On the other hand, the hydraulic motor which drives the reciprocating pump andthe used 7 hydraulic pump, which supplies it, can be made of relatively small capacity but adapted to operate at a substantially higher pressure than that used in the jacks.

It is desirable in an in-the-well pump system to counter-balance the weight of the sucker rod in'some way. A particular advantage of the present invention is that it permits ready compensation for the weight of the sucker rod by applying compressed air to the rear side of the piston of the reciprocating pump, which supplies pressure fluid to the jack. By suitably choosing the air pressure applied to this piston, a force can be readily developed that is sufficient to counter-balance the weight of the sucker rod, without increasing the inertia of the system.

The jack, the reciprocating pump, and the accumulator are connected together in a normally closed hydraulic system from which some leakage will inevitably occur and if such leakage is not compensated for, the supply of fluid will decrease at intervals to the point where it is insuflicient to'lift the jack through the desired stroke. A feature of the present invention is an automatic system responsive to downward movement of the jack below its normal limit to admit additional fluid into the closed system to 'restore the normal amount of fluid.

For a full understanding of the invention, together with other minor objects and features thereof, reference is made to the detailed description and the drawing in which:

Fig. l is a perspective view of a complete pump driving unit in accordance with the invention, shown in operative position with respect to a well;

Fig. 2 is a sectional view of a four-way valve employed in the apparatus; 7

Fig. 3 is an enlarged longitudinal sectional size to 4 view of one of the poppet valve assemblies in four-way valve of Fig. 2;

Fig. 4 is a detailed sectional view illustrating a pressure actuated valve that is employed in the apparatus; and

Fig. 5 is a schematic diagram illustrating the complete system and its mode of operation.

Referring first to Fig. 1, there is disclosed a conventional oil wellhead structure comprising a floor l9 above the well within which there extends the usual well casing l2, the upper end of which is sealed about an oil tube 13, and is provided with a pipe connection [4. The oil tube I3. is provided witha connection l5, through which the pumped oil is delivered, and is closed at its upper end by a'stufiing box [6 through which a conventional polish rod 11 extends. The lower end of the polish rod I! is connected within the oil tube I3 to the upper end of a sucker rod,

'power.

which extends down through the well to a conventional pump located at a substantial depth, which may be many thousand feet. The pump contains a barrel or cylinder, which is anchored in the well, and a reciprocal plunger or piston, which is connected to the lower end of the sucker rod and is reciprocated by. thesucker rod in response to reciprocation of the polish rod H. The apparatus so far described is conventional and constitutes no part of the present invention.

The present invention consists of a driving unit [8 for reciprocating the polish rod ll. As shown, it comprises a cross member is which is clamped to the polish rod l1 and is supported at its outer ends on the plungers 2a of a pair of identical hydraulic jack cylinders or barrels 2|, which are positioned parallel to and on opposite sides of the polish rod [1, and are supported at their lower ends on a pair of frame members 22 which are slidably supported on a pair of track members 23.

In addition to the parts described, the driving unit l8 contains various hydraulic elements positioned within a housing 25, and including a pump which may be drivenby any suitable source of As shown in Fig. 1, the unit includes a motor housing 26 containing an internal combustion motor, the shaft of which is coupled by driving belts positioned within a casing 21 to the shaft of a pump positioned within the casing 25.

The unitary construction depicted in Fig. 1 has the advantage that it can be readily transported to and from a well and can be readily removed for repairs or adjustments. Furthermore, the unit can be easily shifted away from the well by sliding the frame members 22 along the tracks 23 when service work is to be, performed on the well. All that it is necessary to do prior to shifting the unit [8 away from the well along the tracks 23 is to disconnect cross member 19 of pumping jacks from the polish rod I1.

Referring now to the schematic diagram of Fig.

'5, it will be observed that the plungers 20 extend into the upper ends of the jack cylinders 21 through sealing upper end caps 30 of conventional construction. Some seepage of the hydraulic liquid, hereinafter referred to as oil, occurs past the seals 30, and caps 31 may be provided above the seals to trap this oil and conduct it through tube 32 to a drain pan 33.

Oil to actuate the jacks is supplied to the lower ends 34 of the jack cylinders through a conduit 35 of relatively large diameter from the lower end of a pump cylinder 36 containing a piston 31. The diameter of the cylinder 36 and the piston 31, and the stroke of the piston aresuch'as to motor cylinder isconnected by a-conduit4l-and thelower end of the motor-cylinder is connected -by a conduit 42 -to a four-way va1ve-'4'3,=-which valve is connected by a conduit44 to the output of a ;high" pressure pump -45,- and through a conduit46 containing a check-valve l'l'; and a iilter V plied with oil through a conduit 45| from the *reservoirds. Thefour-way valve 43 has'anactuati nglever Ed -which is actuated by a pair of *stopsil and52 on a rod- 5'3 whichis connected by a cross member 54 to-the lower end'of the piston rod -38; for actuation thereby. The construction and operation of the four-way valve4 3 will "be described "in detail'later with reference to Fig. 2. It will sufiiceat this-timetostatethat when the motor-piston 40 reaches --the -lower limit of its stroke, the stopi l' carries the lever 56 past-its center position, whereupon it snaps into a lower position; in which the Valve 43"connects the pressureline-M to-the conduit leading to the lower end of themoto'r cylinder39-and connects the conduit 4| leading from the upper end ,-of the motorcylinder-BB to the exhaust line 46,

"so that the piston 40" is movedupwardly. "Likewise, when the piston- 40 reaches the upper end of- 'its stroke; the stop"52 carries the'lever"50 upwardly to its center position, whereupon it snaps 'intoits upper position, in whichthe valve43 connects the conduit-4| tothe pressure lineM,

and connects the conduit-42 to the" exhaust line -46',--so that the piston -40is then moved down- The-flow of pressure fluid through the pressure line 44 from the pump, to the'four-Way'valve 43' is momentarily" interrupted or reducedeach time the valve'is' reversed, and to reducepressure fluctuationsin-the line4'4 it is connectedtby a branch -line 56 to i anaccumulator 51 "which is shown asof'the type containing a flexible bladder containing nd pressure, the air pr sure being maintained through agconnectionffl containing a check valve BO'to'anair lineBl, which is supplied from any suitable 'source' of compressed air, which is not shown inFig; 5.

A relief valve 62" is alsoconnectedto the pressure line M-for releasing excess pressure" oil back tothereservoir"49througha conduit 63 and prevent the pressure exceeding a predetermined limit. It will be observed that the Weight of the sucker rod is at all'times applied through the polish 'rod l1 andthe cross member lfl to' the r jack plungers 2 0, andistherefore i applied to the oil in the jack'cylinders to maintain a" corresponding pressure therein, which -pressure is *transmittedthrough the conduit 35-to-the oil in the pump cylinder36',- where it is applied-to the under-side ofthe piston 31. Inaccordance'with the present invention this approximatelyconstant upward force'onthe piston 31 is counterbalanced by maintaining compressed air in the 'upper end of the -cylinder 36. For this purpose;

the up er end of cylinder 36 r is "connected to a conduit 61, whichin turnis connected tothe air supply line fil througha check valve 68, so that the pressure in the conduit 61 and-the upper end -of cyIinderBS-isnever less than the pressure in the air supply line -BI. The latter pressure is-so chosen as to exert a downwardforceonthe piston approximately equal to the force developed against the under-side of the piston by the weight of the sucker-rod plushalf the weightof the fluid columnbeing lifted. Of course, as-the piston 37 is moved upwardly in responseto downward movement of the-sucker rod-and the jack plungers 20, the air is compressedpin the upper end of the cylinder 36 so that the force exerted-by the airagainst theupper sideof the piston increases. However; this increase canbe kept within desirable limits'by making the cylin- 'der 36 relatively long, so as to provide a large total volume in the upper partof the cylinder as comparedto the displacement volume of the pis- -ton 31. It is to beunderstood that the cylinder "36 may be much longer in proportion to its diameter than is shown in the schematic "drawing of Fig. 5.

"Fairly constant pressure is maintained on the pressure side of themotor piston '40 during the rnajor part of its stroke, so that the velocity of this-piston, the velocity of the piston 31', and the changes in the velocity of the jack plungers 20,

at dillerent points in their stroke, and to increase theability of the system to maintain relatively constant pressure in the jack cylinders 2| we provide an accumulator '16 of relatively large capacity, directly connected to the conduit 35 by a short, largediameter branch conduit TI.

This accumulator"; is shown as consisting of a cylinder 12 connected atits lower end to the branch conduit H and containing a fioating piston 73. The lower, portion of the cylinder 12, below the piston 73, is filled with oil and the upper portion, above the piston 13, is filled with compressed air, at a pressure equal to the maximum pressure existent in the upper end of the the pressure from rising to a dangerous value,

but it will remain closed during normal operation of the system.

The accumulator 'H] is of relatively-large capacity so as to permit relatively great variations 1 in the velocity of the jack plungers' 20, as compared to the velocity of the pump piston 31,

without'materially changingthe pressurein the jack cylinders2l, conduit 35, and the lower end i of the pump cylinder 36.

This not only facilitates rapid changes in the velocity of the jack plungers 20 in response to changes-in the load applied to the jack plungers by the sucker rod, but makes the demands on the high-pressure pump'45 relatively uniform, thereby reducing the size of the pump -'45 and the'motive means-that drives it.

-- During the operation of'the'system, a certain amount of oil is lost by leakage, such as leakage between the jack plungers 28 and the seals 38,

and provision made for automatically replenishing the supply of oil beforeit drops to a value where it would interfere with the proper operation of the system. Loss of fluid from that portion of the system including the jack cylinders 2I, the conduit 35, the conduit II, the accumulator I8, and thepump cylinder 36, results in lowering of the jack plungers 28 below their normal mean position, and movement of the polish rod I! through only a fraction of its normal stroke. Hence, we providemeans responsive to movement of the jack plungers 28 below predetermined lower limits for admitting additional fluid to the conduit 35. This means includes a pair of spring valves 1'! in the lower ends of the jack plungers 28, which seal against the oil passages 18 in thelower ends of the jack cylinders whenever the plungers drop below their normal lower limits of movement. These valves 1'! are mounted in recesses 19 in the lower ends of the jack plungers 28, and each valve is urgedoutwardly by a helical compression spring 88 so that after spring valves II seat against their associated passages I8, the plungers can continue to move a limited distance. Normally, whenever the plungers 28 are moving downwardly, the oil they displace in the jack cylinders 2| escapes through the opening 18 into the conduit 35. However, after the passages I8 have been closed by the spring valves 77, normal escape of the oil from the jack cylinders is prevented, and the pressure rapidly rises and is applied through conduits BI to a pressure actuated valve 82, which connects the conduit. 35 to a conduit 86 extending to the conduits 44.

A suitable construction of the pressure responsive valve 82 is shown in Fig. 4. It will be observed that it comprises a poppet valve 84, normall seated against a seat 85 to interrupt communication between the conduit 35 and the conduit 86 extending to the high pressure oil line 44. The stem 81 of the poppet extends into a separate cylinder 88 and is secured to a piston 89 therein. A helical compression spring 98 normally maintains the piston 89 in its lowermost position, in which the poppet 84 is seated. The

poppet is also urged into closed position by the high pressure applied to it. Normally the pressure in the conduit BI is never sufiicient to overcome the force of the spring 98 and the force ment as a result of loss of oil from the system and the spring valve 11 closes the passages I8 the pressure in the jack cylinders 2I is suddenly increased to a very high value and this pressure is transmitted through the conduit 8I to the under side of the piston 89 in valve 82 opening the poppet 84 to permit high pressure oil from the conduit 86 to flow into the conduit 35. The poppet 84 is relatively small so as to permit only a limited flow of oil and it remains open only for the short period of time during which the jack plungers 28 are at the bottom of their stroke. However, if the poppet 84 did not remain open long enough to admit sufficient makeup oil on the first stroke, the valves 11 on the jack plungers will again close the passages 18 on succeeding strokes and again actuate the valve 82 until the lost oil has been fully replaced.

A check valve 92 is preferably provided in the high pressure oil line 44; leading to the four-way.

8 valve 43 to prevent return'flow from the motor cylinder 39 when the pump 45 is shut down, and thereby lock the motor piston 48 against reverse movement. a

When starting up the system it is sometimes necessary to replenish the supply of oil in the closed circuit including the jack cylinder 2|, conduit 35, accumulator I8, and pump cylinder 36,

and this can be done by opening a valve 96 which connects the conduit 35 with the condu1t 86 7 leading to the pressure conduit 44.

A valve 98 is provided to by-pass oil from the pressure conduit 44 back to the reservoir and thereby reduce the pressure in conduit 44 when it is desired to move the motor piston 48 slowly into, a desiredposition, as when adjusting the position of the cross head I9 with respect to the polish rod II. The pumping speed can also be controlled by adjusting the valve 98, although it is preferable to do this by varyingthe speed of the pump 45.

Referring now to Fig. 2, the four-way valve 43 comprises four separate poppet valve assemblies I88, I8I, I82, and I83, a11 mounted on a common frame I84 and adapted to be actuated by the control lever 58, which as previously pointed'out, is tripped by stops 5I and 52 on the rod 53 connected to the piston of the hydraulic motor which is controlled by the valve 43.

Each of the valve assemblies I88 to I83 inclusive comprises a poppet I85 (Fig. 3) which seats against a seat I86 and is urged against its seat by a helical compression spring I87. The seat I86 is defined by the orifice of a bore I 88, and the poppet I85 is provided with a downwardly depending skirt I89, which may be slotted or contoured to provide a gradually increasing opening for the flow of liquid as the poppet is lifted 01f its seat. The poppet I85 is also provided with an actuating stem II8, which is guided in a suitable aperture in the frame I84 (Fig. 2). The lever 58 is connected to a shaft III which is rotatably supported and carries a cam II2 which is adapted to bear against the stems II 8 of the poppets. It will be observed that when the lever 58 is in one end position as shown in Fig. 2, the cam II2 opens the poppets in the valve assemblies I 8| and I83. When the lever 58 is in its other extreme position, as shown in dotted lines, the cam II2 closes the poppets in the valves I8I and I83 and opens the poppets in the valves I88 and I82. When the lever is in the position shown in Fig. 2, pressure oil flows from the conduit 44 through a branch conduit I I5 through the open valve I8I, and through a branch conduit II6 to the conduit 4I leading to the top of the motor cylinder 39. At the same time, the conduit 42 leading from the lower end of the motor cylinder 39 is connected, through a branch conduit II! and the open valve I83 and abranch conduit II8, to the conduit 46 which returns to the reservoir. When the lever 58 is in the opposite (dotted line) position, valves I8I and I83 are closed, valve I88 is open, to admit pressure oil from conduit 44 through a branch conduit H9 and a branch conduit I28, to the conduit 42 leading to the lower end of motor cylinder 39, and oil is exhausted from the upper end of the cylinder, through the conduit 4|, a branch conduit I2I, valve I82 and a branch conduit I22, to the conduit 46 leading back to the reservoir.

As has been previously mentioned, valve 43 is .so constructed that following movement of the enemas 9, positionxi The'mechanismlfor accomplishing this, as shown'in 'Fig.:2;comprisesa cam I25 on'the sha-ft I I which moves' past a detent' I26 which is -urged to the left into the path of the'cam I 25 by' the helical compression spring- I21. As the lever 50 moves from either end position to its center position; the cam I 25 depresses the detent I26, thereby loading the spring I2'I,'and as soon as the lever is moved past centerposition, the

reaction of the detent' I26 on thecam'lzfifsnaps the lever into the other end position.

In order to obtain high pumping iefficiency in a :system' of the general type described thejack plungers 20 should have substantially constant force applied to them throughout the major portion of their stroke, their speed being determined solely by the resistance to movement afiordedby:

thetsuckerrod. However, it is desirable to stop the plungers smoothly but'rapidlyat the ends of their stroke. The rate at which the jack plungers arereversed' is in part dependent upon therate at which the pump piston 31 is reversed, which in turn is dependent upon the flow'of fluid to the motor cylinder 39', which, of course, is controlled by the four-way valve 43."

It is desirable to deoelerate the motor piston 40 rapidly but uniformly at the end 'ofitsstroke,

and then accelerate it as rapidly as possible at the beginning of the next/stroke in the opposite direction. This is accomplished by *closing one pair of poppet'valves gradually as the piston 40 approaches tlie'end ofits stroke and opening the other pair of poppet valves suddenly as the piston reaches the end of its stroke; Thisdesired valveaction is obtained by means of springs I32(Fig. 2) and I33 associated with the stops and 52,-"which 'stops are slidable on the rod 53 and contact a trunnion collar I34, which is'slidable' on the rod 53 and: has trunnions I35 engaging slots I36 a bi-furcate end portion of the "lever50'p Thehelical compression spring 532 is compressedbetween the slidable stop 5i and a fixed stop I3'I"secured to the rod 53. The helical compression spring I33 is positioned between the slidable'stop 52 and the cross member 54" which actuates the rod 53. It will "be observed that each of the slidable stops 5! and 'fiz has a stem I38 adapted to limit compression of'the associated spring I32 or I33 by contactiwith the fixed stop I31 or the cross member 54;

As shown inl ig. 2, the rod 53' is in its upper end position corresponding to upper end position of the motor piston 46" (Fig; 5) and the poppet valves iii! and I33 are wide open to deliver pressure fluid 'from the pump conduit 44 to the top end ofcylinder 30-through the cylinder conduit il, and exhaust fiuid from the lower end of cylinder 39 through the cylinder conduit 42, and the valve I63 to'the conduit 06 leading backto the reservoir, The motorpiston will therefore move downwardly at accelerating speed in response tofull pump pressure applied thereabove, its rate of acceleration being limited only by theresistance presented by the pump piston B'Iuntilthe motor piston closely approaches the lower end of its stroke. During this major portion of the downward movement of the motor piston and the rod 53, the valve lever 50 is maintained in its upper position by the detent I26, and the spring I32 compresses without moving the slidable stop 5|. However; slightly before the rod 53 reaches the lower limit of its stroke, the stop 31 contacts the'upper end of the stem" I38 on motor cylinder 39.

10 the slidable stop5I and begins to move it, together withthe collar I34 and the lever 50, to gradually close the valves IM and I03, and increasingly throttle fluid flow to and from the The adjustment'is such that the' lever 50 is carried into its mid or neutral position, in which all the valves I60 to I03 inclusiveare closed; just as the rod 53 reaches the lower limit of its stroke. In this position the compressed spring l32" is able to overcome the'resistance of the detent' I26, andit carries the'lever 56* past neutral position, whereupon the detent spring I21, instead of'opposing the spring I3 2,1as it did' during the first half of the movement"of'leveriil aids the spring I32; andth'e combined forces of "the two springs sud denly snap the lever 50"into fulllower position. This suddenly opens the valves I00 and Iiil'to apply"pressure fluid 'from'the pump to the under sideof the inotor piston 40, and ex haust fluid from the upper side of 'the'piston ba'ck' to-the reservoir." The rod 53" thereupon begins its return movement (with the motor piston 40) and the spring I 33 is compressed by thecross'member Mpuntilthe rod 53 approaches its upper stroke limit and the cross member 54 contacts the stem'l38 ontheslidable? stop 52, whereuponthe lever 50 'is moved backto neutral position inunilson with the rod 53,to gradually close valves'lllliand I02 and throttlethe 'fluid flowto and fromthe motor cylinder 39, to decelerate thepiston 40. When the lever reaches its mid position, the spring I33 carries'it past mid position, and the spring I21 becomes 'effective'to aid thespring I33 and snap the lever 50 into run upper position, there by completing 'a cycle *of' operation;

It will'be 'noted from the foregoing description of-operation, with reference to Fig. 2 that the lever 501s moved positively, with the rod 53 and with the motor piston 40, out of end position. Thainit'ial movement of the lever begins to closethe valve'sthat are controlling flow of fluidto'and' from the-cylinder so that the piston beginsto' decelerate, and movement of the lever 50 decelerates with" the motorpiston to decelerate the movement of the valves as theyapproach closed position Thesupply of pressure 'fluidto" and theexh'austirig of fluid from the m'otoncylinder' is "thereby automatically increasingly throttled to produce a desired smooth deceleration. The rate of deceleration can b'efurther controlled by the shape of the skirts I 00 of the poppet valves, and/or the shape'of' the cam I'I'Z, toobtain the most desirable rate' of "deceleration of the motor piston.

The 'rateiof'movement of the motor piston'LlIl and the pump piston 37 at the end of each stroke is 'largelydetermined" by the characteristics of the'fou'r way valve 43"and the mechanism coupling it "to the 'motor piston 40". However; the jack"plungers20 "are not directly conne'ctedto' the'motor piston'40; and their'mo'vement will difier from the movement of the motor piston-. Thus,'as the pump piston 31 moves down rapidly in response to full application of high pressure oil to the upperend of the motor cylinder 39fromthepump l'ij 'the jack plungers '20 will'lag behind the pump piston'3l, because of the" inertia of thesucker rod, and fluid will flow from the conduit 35- into the accumulator 10 to prevent the pressure in the jack cylinders 2| from rising above-the maximum value the sucker rodis designed to withstand. However, the oil stored in theaccuni-ulator 10 during that portion sure in the jack cylinders 2| throughout the major portion of the upward stroke of the jack plungers.

Downward movement of the jack plungers 20 is produced solely by the weight of the sucker rod and the oil column, but the rate of movement-is limited by the rate at which oil can escape from the jack'cylinders 2! into the pump cylinder 36 during upward movement of the pump piston 31. Initially at the beginning of each upward stroke, the pump piston 31 will move more rapidly than thejack plungers 2!],

and oil will escape from the accumulator into the conduit 35. However, as the pump piston 31 is rapidly decelerated at the upper end of its stroke, the jack plungers 20 will continue to move at a relatively rapid rate because of the inertia of the sucker rod and oil column, and excess oil from the jack cylinders will be forced into the'accumulator 10 and limit the increase in pressure. However, there will be some increase inlpressure in the conduit 35 at the time the pump piston 31 reverses and starts its downward movement, so that maximum pressure is available to start the jack plungers 2|] on their next upward stroke.

The stroke of the jack plungers 20 will vary with different wells and with variations in the fluid level and gas pressure in a given well. In the present system the stroke can be readily adjusted to any desired value by adjusting the position, on the rod 53, of the collar I31, which controls the position in the upward travel of the jack plungers 20 at which the 'valve 43 is reversed. V

Various departures from the particular construction disclosed and described can be made without departing from the invention, which is to be limited only to the extent set forth in the appended claims.

We claim: 1. Apparatus for reciprocating the sucker rod of an in-th'e well pump comprising: hydraulic jack means adapted to be mechanically connected to the sucker rod for directly reciprocating it in response to supply to and release from the jack means of pressure liquid; a liquidconduit connected to said jack means through which said liquid is supplied and released; re-

ciprocating pump means connected to said conduit for successively supplying liquid thereto and withdrawing liquid therefrom during successive strokes of said pump means, and comprising a cylinder containing a reciprocal piston, one end of said cylinder being in direct liquid connection with said conduit and filled with pressure liquid and the other end of the cylinder being filled with a, gas under pressure, and means for reciprocating said pump piston; an accumulator comprising a container directly connected to said conduit and containing a gas under pressure; a gas supply line containing a check Valve connected to said other end of said pump cylinder for supplying gas theretowhile preventing return flow; and means including a check valve connecting said accumulator with said other end of said pump cylinder for permitting gas fiow from said pump cylinder to said accumulator while preventing reverse flow, whereby gas flows from the other end of said pump cylinder in the said accumulator whenever the gas pressure in said accumulator is less than the gas pressure in said other end of said pump cylinder, said ac-l cumulator container containing a movable wall separating the gas and liquid therein and pr'eventing escape of gas into saidconduit.

' 2. Apparatus as described in. claim 1 including a source of 'gas under predetermined pressure and check valve means connecting it to said other end of said pump cylinder. 3. Apparatus for reciprocatingthe sucker rod of an in-the-well pump comprisingz' hydraulic jack means adapted to be mechanically con-' nected to the sucker rod for elevating it in response to supply of pressure liquid to the jack means and lowering it in response to release of liquid from the jack means; ,a, liquid conduit connected to said jack means through which liquid issup'plied to and exhausted 'from said jack'means; reciprocating pump'means con-' nected to said conduit for successively supplying'liquid to'and withdrawing liquid from said jack means during successive strokes of the pump means, for reciprocating said jack means; said hydraulic jack means including a cylinder and means therein reciprocal with said sucker rod for displacing liquid from said cylinder during downward movement of .said sucker rod, said cylinder having a passage in one end through which liquid displaced from said cylinder normally escapes; valve means for closing said passage and preventing escape of displaced liquid when the sucker rod exceeds its normal downward movement; a source of pressure liquid of higher pressure than the maximum pressure in said liquid conduit; and pressure-actuated valve means for admitting liquid from said source to said conduit in response to pressure created in said cylinder by downward movement of the sucker rod following closure of said passage in said cylinder.

4. Apparatus for reciprocating the sucker rod 'of an in-the-well pum-p comprising: hydraulic jack means adapted to be mechanically connected to the sucker rod for directly reciprocat-' ing it in response to supply to and release from the jack means of pressure liquid; a liquid conduit connected to said jack means through which said liquid is supplied and released; reciprocating pump means connected to'said conduitfor successively supplying liquid thereto and withdrawing liquid therefrom during successive strokes of said pump means, and comprising a cylinder containing a reciprocal piston, one end of said cylinder being in direct liquid connection with said conduit and filled with pressure liquid, and the other end of the cylinder being filled with a gas under pressure, and means for reciprocating said pump piston; an accumulator comprising a container directly connected to said conduit and containing a gas under pressure; said means for reciprocating said pump piston comprising: a hydraulic motor. having a cylinder, and a piston therein directly connected to said pump piston; a source of pressure liquid; and valve means for successively admitting pressure liquid from said source to opposite ends of said motor cylinder while exhausting liquid from the other end, in which said valve means comprises fourpoppet valves,.

one pair of which are connected between one end of said motor cylinder and exhaust, and between the other end of said'motor cylinder and said pressure source, respectively, and theother pair of which are connected between said one end of said motor cylinder and said pressure source and between the other end or said motor cylinder and exhaust, respectively, and a mechanism responsive to movement of said motor piston for slowly closing one pair of said poppe'ts as said motor piston approaches one end of its stroke, and suddenly opening said other pair of poppets as said piston reaches said end of its stroke.

5. Apparatus for reciprocating the sucker rod of an in-the-well pump comprising: hydraulic jack means adapted to be mechanically connected to the sucker rod for directly reciprocating it in response to supply to and release from the jack means of pressure liquid; a liquid conduit connected to said jack means through which said liquid is supplied and released; reciprocating pump means connected to said conduit for successively supplying liquid thereto and withdrawing liquid therefrom during successive strokes of said pump means, and comprising a cylinder containing a reciprocal piston, one end of said cylinder being in direct liquid connection with said conduit and filled with pressure liquid, and the other end of the cylinder being filled with a gas under pressure, and means for reciprocating said pump piston; an accumulator comprising a container directly connected to said conduit and containing a gas under pressure; said means for reciprocating said pump piston comprising: a hydraulic motor having a cylinder, and a piston therein directly connected to said pump piston; a source of pressure liquid; and valve means for successively admitting pressure liquid from said source to opposite ends of said motor cylinder while exhausting liquid from the other end, in which said valve means comprises four poppet valves, a first pair of which are connected between one end of said motor cylinder and exhaust, and between the other of said motor cylinder and said pressure source, respectively, and the other pair of which are connected between said one end of said motor cylinder and said source and between the other end of said motor cylinder and exhaust, respectively, and a mechanism responsive to movement of said motor piston for slowly closing one pair of said poppets as said motor piston approaches one end of its stroke, and opening said other pair of poppets as said piston reaches the end of its stroke; the two poppet valves connected to said liquid pressure source, each comprising a seat and a poppet reciprocal toward and away from the seat, the poppet having an inwardly extending skirt slidable within the seat, and the skirt having such contour as to increasingly throttle fluid flow through the seat as the poppet approaches the seat.

6. Apparatus for reciprocating the sucker rod of an in-the-well pump comprising: hydraulic jack means adapted to be mechanically connected to the sucker rod for directly reciprocating it in response to supply to and release from the jack. means of pressure liquid; a liquid conduit connected to said jack means through which said liquid is supplied and released; means connected to said conduit for successively supplying liquid thereto and withdrawing liquid therefrom for reciprocating said jack and comprising a counterbalancing chamber partially filled with liquid and partially filled with gas under pressure, said chamber being so connected to said jack that the pressure therein opposes downward movement of the sucker rod; an accumulator comprising a container having a movable wall therein separating the interior of the container into a gas compartment and a liquid compartment; means connecting said liquid compartment directly to said conduit; a gas supply line containing a check valve connected to said counterbalancing chamber for supplying gas thereto while preventing return flow; and means including a check valve connecting the gas compartment of said accumulator with the gas-containing part of said counterbalancing chamber for permitting gas flow from said counterbalancing chamber to said accumulator while preventing reverse flow, whereby gas flows from said counterbalancing chamber into said accumulator whenever the pressure in said counterbalancing chamber exceeds that in said accumulator.

WALTER C. TRAUTMAN.

EZRA HOLLISTER.

40 file of this patent:

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