US2122871A - Method and apparatus for counterbalancing oil well pumping apparatus - Google Patents

Description

July 5, 1938.

W. E. SAXE METHOD AND APEARATUS FOR CCUNTERBALANCING OIL WELL PUMPING APPARATUS 2 Sheets-Sheet l WALTER E. SAXE Jly 5, 1938. w. E. sAxE 2,122,871

` METHOD AND APPARATUS FOR COIUNTERBALANCING OIL WELL `PUMPING APPARATUS Filed Sept. 29,` 1936 2 Sheets-Sheet 2 mu-ER E. JAA/f Y Patented July 5, 1938 PATENT OFFICE METHOD AND APPARATUS FOR COUNTElt- BALANCING OIL WELL PUMPING APPA- RATUS Walter E. Saxe,Y Altadena, Calif. Application September 229, 1936, Serial o. 103,169 1s claims. (ci 'I4- 589) My invention relates to a method and appa'- ratus for counterbalancing, and particularly to a method and apparatus for counterbalancing a reciprocating member which is driven by a rotating shaft and which if not counterbalanced, subjects the rotating shaft to unequal loads upon its two-strokes. 1

My .invention nds particular utility in the counterbalancing of pumping apparatus for oil l4 l wells, and an embodiment of the apparatus of my invention and apparatus capable of performing the method of my invention will be described in connection with such use, it being understood that my invention is not limited to suchl use.

l5 It is a general object of my invention to pro-4 vide a method of and apparatus for equalizing the load upon a prime mover of an oil well pump so that this load is substantially equal in the two strokes of the pump plunger and substantially 2O equal throughout the various portions of each stroke. y

It is a more speciiic object of my invention to provide a method of and apparatus for equalizing the maximum loads to which a ^prime mover 25 driving the pump plunger is subjected in the two strokes of the pump plunger.

As a pump plunger nears the end of its downward stroke it is decelerated until it comes to rest at the lower end of its stroke. The pump 30 plunger, string of sucker rods and walkingbeam,`

all of. which are subjected to this deceleration, have considerable momentum at the midpoint of their downward stroke, and this energy of momentum must be dissipated during the travel of these reciprocating parts in the second half of their downstroke. During the rst half of the upstroke of these reciprocating parts they are accelerated; therefore, without counterbalancing, the load upon the prime mover during the latter 40 half of the downstroke of the reciprocating parts is greatly lessened by their deceleration and during the first half of the upstroke of the reciproeating parts the load on the prime mover is great^ to employ a prime mover for rotating a shaft and to translate the rotary movement of such shaft to the reciprocating movement of a pump plunger through a crank arm,- or eccentric mounted on a wheel equivalent to a crank arm, and a walk- 5 ing beam. During that time in the use of such apparatus at which the crank arm is nearly ver- I`tical it has a. relatively small component of its angular movement parallel to the direction of travel of the walking beam and the pump plunger and therefore the load upon the prime mover during a given angular movement of the crank arm in such position is relatively small. On the other hand, when the crank arm is near either of its horizontal positions it has 4a relatively large 15 component of its movement parallel to the direction of travel of the Walking beam and the pump plunger and therefore the load upon the prime mover during the same given-angular movement, of the crank arm in such position is relatively great.

It is an object of my invention to provide a method and apparatus for making the loads upon the prime mover substantially equal when the crank arm is moving near either of its vertical positions and when the crank pin is moving near either of its horizontal positions.

More specifically, it is an object -of my invention to provide amethod and apparatus for accomplishing the object last stated which utilizes a counterweight -rotated twice for each revolution of the crank arm, storing energy when the crank arm is near its vertical positions, and returning energy to the crank arm when the crank arm is near its horizontal positions.

It is still another object of my invention to equalize the maximum loads upon the prime mover during the two strokes of the pump plunger by compressing a gas during that stroke of the plunger during which the prime mover is normally subjected to the lesser load, and expanding the gas during that stroke of the pump plunger in which the prime mover is normally subjected to its greaterload.

It is still another object of my invention to'45 provide a method and apparatus for maintaining this equalization by maintaining substantially constant the quantity of gas subjected to such compression and expansion in spite of leakage.

Il nd it advantageous to compress such gas by pumping a liquid into a closed chamber of gas. and it is a further object of my invention to provide a method of and apparatus for maintaining constant the quantity of liquid so pumped to maintain constant the Vcounterbalancing eect thus achieved.

It is sometimes necessary to disconnect the string of sucker rods and the pump plunger from the Walking beam in order to work upon the well. The pumping apparatus being counterbalanced for the load of the pump plunger and string of sucker rods, the equilibrium of the apparatus is upset by such disconnection. It is a purpose of my invention to provide a method of and apparatus for preventing the movement of the driving apparatus and walking beam when the string of sucker rods and the pump plunger are disconnected from the walking beam.

In accomplishing the foregoing objects I may utilize a piston reciprocable in a cylinder, and it is an object of my invention to provide a method of and apparatus for maintaining a body of lubricating and sealing liquid in contactwith the piston and wall of the cylinder when a piston and cylinder apparatus is so used.

These and other objects and advantages of my invention will be made evident in the following description which may be better understood by a reference to the accompanying drawings in which,

Fig. 1 is an elevational view partially sectioned of the counterbalancing apparatus of my invention;

Fig. 2 is a sectional view of a part of the load counterbaiancing apparatus illustrated in Fig. i;

Fig. 3 is a sectional view taken as indicated by the line 3 3 of Fig. 2;

Fig. 4 is an elevational view, partially sectioned, of a locking mechanism of my invention;

Fig. 5 is a sectional view of a pump employed in my counterbalancing apparatus; and

Fig. 6 is a sectional view taken as indicated by the lines 6-6 of Fig. 5.

Referring to the drawings, which are for illustrative purposes only, the numeral I I indicates an oil well having therein a casing I2 and a pump tubing I3 in the lower end of which a pump plunger I4 is reciprocated by a string of sucker rods I5. The sucker rods I5 extend upwardly through the pump tubing to above the surface of the ground and are attached to the working end of a walking beam I6, the other end of the walking beam in the form illustrated in the drawings being mounted upon a pivot I1 carried by a Samson post I8. Secured to \the walking beam I 6' intermediate its ends is a pitman I9 which is connected to an eccentric or a crank 2|. 2| is mounted upon a crank shaft 22 to which a crank shaft gear 23 is non-rotatably secured. A chain 24 meshes with `the crank shaft gear 23 and a smaller gear-25 carried by a second countershaft 26. The second countershaft 26 has mounted thereon a driven gear 21 with a chain 23 meshing therewith and with a driving gear 23L the `prime mover is'energized Ithe drive shaft 34' drives the first countershaft 30 and the second countershaft 26 and thus the crank shaft 22 and the crank 2|, thus rocking the walking beam I6 i about the pivot I1 and reciprocating the sucker rods I5 and plunger I4 in the well. The recipro- `cation of the plunger I4 elevates liquid in the Well so that it may be discharged at the surface in the manner well known in the art.

The crank If no counterbalance is employed, it is apparent that on the upstroke of the string of sucker rods I5 the prime mover is subjected to the load of the walking beam I6, the string of sucker rods I5, and all of the liquid being elevated in the tubing I3, and on the downstroke of the plunger I4 the walking beam I6 andstring of sucker rods I5 fall by gravity, subjecting the prime mover to little or no load. For the purpose of making the maximum load upon the drive shaft 34 on the downstroke of the plunger I4 equal to the maximum load on the drive shaft on the upstroke of the plunger I4, I have provided a load counterbalance indicated generally by the numeral 36 of Fig. 1. The load counterbalance includes a cyl inder 31 open at its upper end to the atmosphere and secured at its lower end in any suitable manner to a housing 33 with which it freely communicates. Reciprocable within the cylinder 31 is a piston 39 having a connecting rod 40 pivotally connected in its upper face. The connecting rod 4I) is pivoted at its upper end to the walking beam I6, the connections of the connecting rod 40 and the pitman I9 to the walking beam I6 being at substantially the same distance from the pivot I1.

The housing 38 communicates with an expansion chamber 4I which has positioned thereabove a supply tank 42. The expansion chamber 4I is provided with a valved supply pipe 43 for the introduction of liquid to the' expansion chamber 4 I,

housing 38 and cylinder 31. Liquid may thus be 44 with a second expansion tank 46 having a valved liquid supply pipe 41. The second expansion chamber may be shut oi from the expansio chamber 4I or connected thereto and filled with gas or liquid and gas, dependent upon the degree ofl compression of the gas that is desired. 'I'he piston 39 is provided with piston rings 43 of conventional construction to restrain the passage of liquid outwardly of the cylnder31 between the piston 39 and the cylinder wail.

By varying the space i-n the expansion chamber 4I above the liquid level 44 and the volume of the second expansion chamber 46 filled with gas if the second expansion chamber is connected to the expansion chamber 4I and thus varying the gas volume relative to the displacement of the piston 39 the degree to which thegas is comtom of the piston 39 may be varied. 'Ihus it is possible for the gas compressed in the expansion chamber 4I or chambers 4I and 46 to exert an upward force on the bottom of the piston 33 when the piston is at the lower end of its stroke equal to thatI weight of the walking beam I6 and string' of sucker rods I5 and one-half that weight of the liquid being elevatedvin the tube I3 which is effective at the point at which the connecting rod 40 is pivoted to the walking beam I6. For example, if the connecting rod 40 is pivoted to the walking beam I6 at a. distance of twelve feet from the pivot I1 and the string of sucker rods I5 is attached to the walking beam'I6 eighteen feet from the pivot I1, and the walking beam has a weight of 2000 pounds effective at the point at which the string of sucker rods is attached to the beam, and the sucker rods have a weight of 3000 pounds, and-the fluid has a weight of 6000 pounds, the gas can becompressed in the expansion chamber 4| or chambers 4I and 45 when the piston 39 is at the lower end of its travel so that there is exerted upon the piston 39 and the walking beam I6 an upward force equal to 2000 pounds plus 3000 pounds plus one-half of 6000 pounds, or a total of 8000 pounds times a lever arm of three halves, or 12,000 pounds. With the load so counterbalanced the prime mover 35 is compelled on the upstroke to lift only one-half of the liquid load, or 3000 pounds effective at the point of connection of the string of sucker rods to the beam in the example, the Walking beam and the string of sucker rods I being lifted by the expansion of the gas. Likewise on the downstroke of the pump plunger I4 theprime mover is compelled to exert a force equal to one-half the liquid load, or 3000 pounds effective at the point of connection of the string of sucker rods to the beam in the example, this force together with the .effective Weight of the walking beam' and the sucker rods at the point of connection of the connecting rod 40 to the walking beam I6 be- A ing necessary to force the piston 39 to the lower end of its stroke and to compress the gas to its required volume.

In order to compensate for the leakage of gas the supply tank 42 is maintained filled with gas at a higher pressure than the maximum pressure upon the gas in the expansion chamber 4|. A valve 48a is interposed between the supply tank 42 and the expansion chamber 4I, this valve being oi" a construction well known in the art, to permit the passage of gas from the supply tank 42 to the expansion chamber 4I to maintain the pressure in the chamber 4I above a predetermined value. Gas is supplied to the supply tank 42 through a conductor pipe` 49 from an auxiliary cylinder 5D, the conductor pipe 49 containing a valve 49a for passing gas to the chamber 42 when the pressure therein falls below a predetermined value. The auxiliary cylinder 50 is mounted upon the housing 38 and has reciprocable therein a piston 5I 'connected through a connecting rod 52 with the walking beam I6. The volume of displacement of the auxiliary piston 5I and the volume ofr the conducting pipe 49 is made less than the volume of the gas space in the expansion chamber 4I so that although the auxiliary piston 5I has a 'stroke substantially equal to the stroke ofthe piston 39'A the gas is compressed in the auxiliary cylinder 50 to the desired extent above the maximum pressure on the gas in the expansion chamber 4I.

rAs the pump plunger I4 nears the lower end of its stroke' the walking beam I6 and string of sucker rods I5 have momentum ofy considerable value Vthat must be dissipated. I absorb the energy of this momentum and store it for imparting'momentum during the rst part of the upstroke of the plunger I4 by means ofthe auxiliary cylinder 50 and piston 5I. As illustrated in Fig. 1 the cylinder 50 is provided with a series of ports 52a intermediate the ends of the stroke of the auxiliary piston 5I. A sleeve 53 is rotatably mounted upon the .auxiliary cylinder 50 in air tight relationship therewith and has.

openings 54 therein. The openings 52 and 54 are spaced both. circumferentially 'and longitudinally in the auxiliary cylinder 50 and sleeve 53, respectively, the openings in the cylinder 50 beingl offset circumferentially'in a direction opy posite'to that in which the openings in the sleeve 53 are offset. Thusv by rotating the sleeve 53 upon the cylinder 59 the openings 52a and 54 at diierent elevations are brought into coincidence. As the pump plunger I4 moves downwardly the auxiliary piston 5I moves downwardly in the cylinder 50. No compression of gas occurs in the auxiliary cylinder 50 until the piston 5I has covered that one of the openings 52 registering with one of the openings 54. Thus resistance to the downward movement of the walking beam I6 ands string of sucker rods I5 is offered only during the latter part of the downstroke of the plunger I4. The momentum of the walking beam I6 and string of sucker rods I5 is thus absorbed and their downward movement is decelerated until the reversal of movement occurs and the pump plunger I4 begins its upward stroke. As soon as the plunger I4 begins its upward stroke the gas compressed in the auxiliary cylinder 50 exerts its compressive force urging the walking beam I6 and string of sucker rods I5 upwardly, and this accelerating force is applied until the auxiliary piston 5I uncovers that one of the openings 52 registering with one of the openings 54. While it is possible by adjusting the sleeve 53 upon the auxiliary cylinder 50 to compress gas in the auxiliary cylinder 50 during any desired part of the stroke of the auxiliary piston 5I, I have found that good results are secured if the sleeve 453 is so adjusted that the auxiliary piston` 5I covers the registering openings when about one-half of the downstroke of the walking beam I6 has occurred. I have found that it is not necessary to provide an auxiliary cylinder such as the auxiliary cylinder 59 to decelerate the walking beam I5 and string of sucker rods I5 as they approach the upper end of their stroke since their weight is suilicient to accomplish this deceleration.

It is possibleto employ in the expansion cham- .ber 4I a pressure somewhathigher than that required to counterbalance the effective weight of the walking beam I6, string oi' sucker rods I5 and one-half the liquid load, this excess in pressure being utilized to decelerate the walking beam I6 and string of sucker rods I5 as they near the y lower end of their travel andto accelerate them as they begin their upstroke. However, this excess of pressure is exerted also in the upper part of the upstroke and tends to cause racing as the walking beam and sucker rods reach the end of their upstroke and begin their downstroke. A

- 5% increase in pressure in the gas in the expansion chamber 4I over that necessary to counterbalance the effective weight of the walking beam I5, string of sucker rods I5 and one-half the liquid load I have found can be utilized.

When the crank is in the position indicated by k dotted lines of Fig. 4 the prime mover is sub- Jected to greater load than when the crank is in the positions indicated by the full and dotted lines in Fig. 1 since when the crank is lin its horizontal position the ratio of the vertical component of the velocity of the free end of thel crank to the angular velocity of the crank shaft 22 is greatest. To make the load upon the drive shaft 34 more nearly equal throughout each' stroke of the walking beam I5 I apply a counterweight 51 to the apparatus. This counterweight is applied to the apparatusv so that it revolves twice for each revolution of thegcrank shaft 22. If the driving gear 25 ismade of half the circumferenceof the driven gear 23 on the crank shaft 22, the counterweight 5l' may be applied directly ,tol the second countershaft 26, and I have-illustrated it in this position in the drawings'. The counterweight 5l is non-rotatably sei cured in any suitable manner to the second countershaft 26 so that it is horizontal when the walking beam is at each end of its stroke. Thus ,when the crank is in the position indicated by the dotted lines of Fig. 4 the counterwelght51 is in its horizontal position and descending so that it is imparting its maximum energy to the second countershaft 26 and to the crank shaft 22, thus diminishing the load 'upon the drive shaft 34.l When the crank shaft is in its vertical position illustrated in the full lines of Fig. 4 the counterweight 51 has rotated 180 and is in its horizontal position and ascending so that lit is absorbing its maximum energy from the drive shaft 34. If the maximum pull on the chain 23 when the `crank 2| is horizontal is 1500 pounds, for example, and the maximum pull upon the chain ,when the crank is in either of its vertical positions is zero or nearly zero, I install a counterthe upper end of the piston 39 when the piston is at the upper end o f its stroke to provide a liquid reservoir 60. The liquid leaking from the cylinder 31 around the piston 39 is thus collected in the reservoir 60 where it exerts a sealing and `lubricating function between the piston 39 and the wall ofthe cylinder 31. In order that the counterbalancing eect of the expansion and contraction of the gas in the expansion chamber 4| shall be maintainedconstant, it is necessary to maintain substantially constant the volume of liquid within the cylinder 31, housing 33 and expansion chamber 4|. For the-purpose of retum' ing to the system the oil which has leaked therefrom, I provide in the piston 39 a vertical cylindrical opening 6| communicating with the top of the piston 39 at its upper end and communieating with 'a transverse bore 62 at its lower end. The transverse bore 62 extends through an annular skirt |53 of the piston 39 and has its outer end closed by a screw 64. Secured in the inner end of the transverse bore 62 Iis a discharge pipe 65 to which a valve 66 is connected. The valve 66 may be of any conventional construction for discharging fluid from the pipe 35 to the interior of the cylinder 31 when the pressure in the cylinder 31 falls below a predetermined minimum value and the pressure in the discharge'pipe 65 is -above this value. Reciprocable within the cylindrical opening is a plunger 61 which projects above the upper end of the; piston 39 and is provided near its upper` end with' a collar 6 9.v

to the periphery of the piston 39, being closed at the periphery of the piston 39 by a screw plug 16 threaded into the piston 39. A vertical control pipe 11 may be threaded into the upper end oi' the vertical lsupply pipe 14 so that its upper end projects above the upper end of the piston 39 a variable distance for a purpose which will now be described. i

As the liquid in the cylinder 31 leaks therefrom around the piston 39 it collects in the liquid reservoir 60. This body of liquid travels withthe piston 39 in contact with its upper surface. As the piston 39 moves upwardly the compression spring 69 resiliently urges the plunger 61 downwardly in the cylindrical bore 6|. 'Ihe length of stroke of the plunger 61 may be varied by adjusting the bolt 1|, moving it upwardly or downwardly. 'I'he stroke of the piston 31 is adjusted so that if 4any gas issupplied through the supply passages 14 and 15 the gas is compressed to a pressure less than the minimum pressure at which the valve 66 will discharge fluid from the cylindrical bore 6| into the cylinder 31. However, the stroke of the plunger 61 is maintained great enough to exert a pressure on the liquid contained in the cylindrical bore 6|, if this bore is filled with liquid, to a pressure greater than the minimum pressure at which the valve 66 will discharge uid from the cylindrical bore 6| into the cylinder 31. Thus as long as the cylindrical .bore 6| below the plunger 61 is illled with liquid the liquid will be compressed to such an extent that the valve 66 will discharge this liquid into the cylinder 31 to maintain substantially condepth equal to the length of the control pipe 11 projecting above the piston 39 so that some liquid is maintained at all times in lubricating relationship with the piston 39 and the wall of the cylinder 31 and in lubricating relationship with -the plunger 61 and the wall of the cylindrical bore 6|. The depth of this body of liquid may be readily varied by threading the control pipe 11 into or out of the vertical supply passage 14.

If it is desired to vary the quantity of liquid in the cylinder 31, housing 36 and expansion chamber 4| to vary the counterbalancing eilect of the expansion and contraction of the gas in the expansion chamber 4|, this may be accomplished 7 by threading `the control pipe 11 into or out of the vertical supply passage 14 and if desired, by adding liquid` to the reservoir 60. The quantity of gas within the expansion chamber 4| is maintained substantially constant by the discharge through the valve 49a of gas compressed by the auxiliary piston 5| when the'pressure within the expansion chamber 4| falls below a predetermined value.

If desired a gas compressing pump, indicated generally by the numeral 19 or Fig. 4 may be emprojecting po'rtion 59 ofthe cylinder 31. A sec\ -ployed instead of the auxiliary cylinder 50 for ond compression spring 13 surrounds the plunger maintaining substantially constant the quantity 61 with its upper end bearing against the lower surface of the collar 63 and its lower end bearing against the upper end of the piston 39.

Formed vin the piston 39 is a vertical supply pipe 14 communicating at its upper end with the top of the piston 39 and at its lower end with a` horizontal supply pipe 15. 'I'he horizontal supi 'ply pipe 16 extends from the cylindrical bore 6| of gas in the expansion chamber 4|. This gas compressing pump 19 includes a cylinder 30 having a piston 8| reciprocable therein, this piston being connected as illustrated in Fig. 5 by a connecting rod 32 to a crank 33 on the second coun-y tershaft 26. An intake port 34 ls provided at the lower end. of the cylinder 39 and is closed during the compression stroke of the piston 3| by a valve ymember 85. 'I'he valve member 85 is resiliently urged to position closing the intake port 84 by a compression spring 88. When the piston 8 Imoves upwardly the decrease in pressure in the cylinder 88 causes the valve member 85 to move inwardly against the resistance ofthe spring 88 opening the intake port 84 and permitting air to enter the cylinder 88. When the piston 8| :noves downwardly the spring 88 urges the valve member 85 into position closing the intake port 84 which position it maintains during the `compression stroke of the piston 8|. Air compressed in the cylinder 88 is discharged therefrom through a discharge pipe 81 communicating with the gas supply chamber 42. The discharge pipe 81 has a valve 88 therein permitting the passage of gas through the discharge pipe 81 only in one direction, i. e., from the cylinder 88 to the high pressure chamber 42.

While I have illustrated the connecting rod 82 as driven by the second countershaft 28, it' will be obvious that the connecting rod may be driven by any other driving or driven part of the apparatus.

For the purpose of lubricating the piston 8| I provide in the lower end of the auxiliary cylinder 88 an upwardly extending annular flange 88, illustrated in Fig. 5, which cooperates with the wall of the auxiliary cylinder 88 in defining an annular lubricant chamber 88. Formed on the lower end of the -piston 8| is a carrying member 8| which4 includes a vertical wall 82 adjacent the wall of the cylinder 88, a horizontal wall 83 and an inner vertical wall 84 of lesser length than the outer vertical wall 82. Openings 85 are provided in the outer vertical wall 82 for the escape of lubricant from the carrying member 8|. In Fig. 5 the auxiliary piston 8| is illustrated in the lower end of its stroke with the carrying member 8| submerged in the lubricant contained in the annular chamber 98. As the piston 8| moves upwardly in the cylinder 88 the lubricant contained in the carrying member 8| is discharged therefrom through the openings 85 to the space between the outerV vertical member 82 and the wall of the auxiliary cylinder 88. This space is made .of small radial thickness so that a fllm of oil is maintained therein from. the discharge of the carrying member 8| throughout the upward and downward strokes of the auxiliary piston 8|. A valve member 88 communicates through a passage 81 with the annular lubricant chamber 88 to enable the operator to determine whether the chamber is filled with lubricant and to add to the body of lubricant in the annular chamber when necessary.

When it is desired to disconnect the string of sucker rods I from the beam I8 to work upon g the well, itis desirable to maintain the gas under pressure in the expansion chamber 4| so that the energy expended in accomplishing this compression will not be wasted. I therefore provide a latch member |88 which is swingably mounted upon a pin I8I mounted in the housing 88. The

latch member |88 is swingable from the posi-l tion illustrated in the full lines of Fig. 4 in which position a hook |82 on its inner end engages a horizontal pin |88 secured to the lower end of the piston' se to the position illustrated in the dotted lines of Fig. 4 in which position the pin |83 and the piston 3i!y are released so that the'piston may freely reciprocate. An rarm |84 is .mounted upon the pin I8I exterior of the housing 38 for moving the latch member |88 between its two positions. Thus when it is desired to disconnect the string of sucker rods I5 from the beam I8 the piston 38 is moved to its lowest position by the prime mover 85 and the arm I.84.is swung to accomplish the engagement of the pin |88 by the latch member |88. The sucker rods may then be disconnected from4 the beam and the pistons 5| and 88 will be maintained stationary.

Illustrated in Fig. 1 is anothermeans of maintaining the piston stationary when the sucker rods are disconnected from the beam. This means includes a worm gear |81 rotatably supported in a journal member |88, one end oi.' which is swingably mounted upon a pivot |88 carried by the Samson post I8. The other end of the journal member |88 is pivotally connected to a supporting member II8. When the supporting member II8 is moved into its vertical position with its lower end abutting a stop ||I secured to the derrlck floor, the worm gear |81 is maintained in meshing relationship with a gear I|2 non-rotatably secured to the first countershaft 88. When the supporting member II8 is swung relative to the journal member |88 until its lower end abuts againsta second stop I|8 secured to the derrlck floor. the worm gear I81"is swung downwardly about the pivot |88 out of engagement with the gear II2. A handle II4 secured to the wormA gear I 81 projects beyond the journal member |88 so that the worm gear may besmanually rotated.

When it is desired to disconnect the string of sucker rods I5 from the beam I8 using this embodiment of my invention, the prime mover 85 is shutdown and the supporting member |I8 is moved from the' position indicated in the dotted lines of Fig. l'to the position indicated in the full lines of this figure. The handle II4 is then rotated, moving the pistons 38 and`5| until the walking beam I8 is in its desired position. The sucker rods are then disconnected from the beam I8, the worm gear |81 preventing rotation of the gear I|2 and first countershaft 88, and thus preventing movement of the pistons 38 and 5I.

While I have illustrated the worm gear |81 as associated with the first countershaft 38,it may be associated with any suitable shaft upon the apparatus. Likewise, while the counterweight 51 is illustrated asV appliedv to one of the shafts in the train of countershafts between the prime mover and the crank 2| this counterweight may be applied to any shaft so related to the crank' shaft 22 as to rotate at twice nthe angular velocity of the crank shaft 22.

While I have described the variations in load as occurring at certain positions of the crank, or other parts of the apparatus, I am aware that due to conditions such as expansion and contraction of the string of sucker rods, deformation of the walking beam' and Samson post etc. these variations may actually occur at positions of the crank different from the exact positions I have described, and therefore such positions as I have described for load variations must be understood to be variable in accordance with such conditions.

The foregoing apparatus constitutes one embodiment of apparatus of my invention and one embodiment oi apparatus capable of performing the method of my invention. The methodof my invention includes the step of making the loads upon the prime mover substantially .equal during the two strokes of a reciprocating memby compressing a gas in the expansion chamber., 4| during one stroke of the reciprocating member and thus storing energy, and expanding this gas during the succeeding stroke of the reciproeating member and thus applying energy to the reciprocating member.

The method of my invention also includes the step of storing the energy freed by the loss of momentum during the deceleration of the reciprocating member during one stroke and applying this energy to thereciprocating member during the acceleration period of its succeeding stroke. As illustrated in the drawings this may be accomplished by compressing a gas in the auxiliary cylinder 50 during only the second half of the downstroke oi the reciprocating member and expanding this gas during only the first half of the succeeding 'upstroke of the reciprocating member. By this stepmy method equalizes the load upon the prime mover during the deceleration of the reciprocatingV member on one stroke and its acceleration on the succeeding stroke.

My method also includes the step of equalizing theloads upon the prime mover when the crank is near its dead center positions and when the crank is in its positions farthest from dead center. As illustrated in the drawings, this may be accomplished by utilizing a counterweight rotating at twice the angular velocity of the crank, the counterweight, such as the counterweight 51, storing energy while the crank is approaching and passing through and beyond its dead center position, and restoring energy to the system as the crank approaches its next position farthest from dead center.

My method also includes the step of maintaining the load counterbalancing effect substantially constant. As illustrated in the drawings, this may be accomplished by replacing in the expansion chamber 4| gas which escapes therefrom and by returning to the cylinder 31 and expansion chamber 4| liquid which escapes therefrom so that the volumes of liquid and gas in the chamber 4| are maintained substantially constant.

My method also includes the step of utilizing the means for storing energy during the deceleration of the reciprocatingmember and returning this energy to the system during thel succeeding acceleration of the reciprocating member, for maintaining substantially constant the volume of gas in the load counterbalancing means. As pointed out in the foregoing specification, this is accomplished by storing the energy of deceleration by the compression of a gasand conducting the required amount of such compressed gas to the expansion chamber 4| through the storage chamber 42.

My method also contemplates the provision of a body of lubricant in lubricating relationship with the piston and cylinder wall of the load counterbalanclng means, the inertia counterbalancing means and the liquid return means. This may include the mechanism by which a body of, lubricant is maintained on top of the 'piston 39 and below the piston 8l, as hereinbefore described.

While that embodiment of the apparatus of my I invention hereinbefore illustrated and described is fully capable of performing the objects and ad- .vantages primarily stated and of performing the method of my invention, the apparatus of my invention maybe embodied in other forms and the method of my invention Vmay be performed by other apparatus, and I therefore wish my invention to be understood as not restricted to the spe- 'to and accelerating. the member on its succeeding stroke whereby the loads on the drive shaft near the end of one stroke and the beginning of the succeeding stroke are substantially equalized; and means absorbing energy when Vthe crank arm is near dead center position and delivering energy when the crank arm is farthest from dead center position whereby the load on the drive shaft is substantially uniform throughout the stroke.v

2. In an apparatus including a drive shaft for reciprocating a pump plunger, the combination of: means lcounterbalancing the weight of the reciprocating parts and one-half the weight of the liquid lifted by the plunger; means absorbing the energy. of momentum of the reciprocating parts during the latter part of their downstroke and applying energy to accelerate the reciprocating parts during the early part of their upstroke; and means storing energy when the reciprocating `members are near the end of their strokes and applying energy thereto when said members are near the middle of their strokes.

3. In an apparatus for' reciprocating a pump plunger, including a drive shaft and a crank, the combination of means counterbalancing the reciprocating parts whereby the loads on the drive shaft on the up and down strokes of the plunger are substantially equal, said means including a fluid pump; and means decelerating the reciprocating parts near the end of a stroke and accelerf ating the reciprocating parts near the beginning of the succeeding stroke, said means replacing in said fluid pump of said first named means fluid escaping therefrom.

4. In an apparatus for reciprocating a pump plunger including a drive shaft and a crank, the combination of: means counterbalancing the reciprocating parts whereby the loads on the drive shaft on the up and down strokes of the plunger are substantially equalized, said means including a piston adapted for pumping liquid in a cylinder to compress a gas in a chamber; return means for returning to the cylinder liquid which has l passed between saidpiston and cylinder whereby the volume of liquid in said cylinder and chamber is maintained substantially constant; pump means, including an auxiliary piston and cylinder, taking energy from the reciprocating parts i only during their deceleration by vcompressing a gas and delivering energy to the reciprocating parts only during their acceleration of the succeeding stroke by expanding the gas, said auxiliary cylinder having a body of lubricant therein; l a cup shaped `member on the lower end of`said auxiliary piston dipping into the body of lubricant at the lower end of each stroke, said member having openings therein for the discharge of a sealing lubricant film between said member and .i the wall of said auxiliary cylinder during travel of said auxiliary piston; means storing energy when the crank is near dead center position and delivering energy when 'the crank is farthest from dead center positionf whereby the load on the 7 and means manually operable independently of said drive shaft for moving said plungerand preventing movement of. all of said means when said plunger is disconnected from said crank.

'7. In combination: a walking beam; means for pivotally supporting said walking beam; means for rocking said walking beam; pump means in a well; connecting means extending from said walking beam to said pump means whereby the rocking of said walking .beam actuates said pump means; a stationary member; a' movable member connected to said walking beam ,and associated with said stationary member to provide a fluid-tight chamber variable in volume in response to the rocking of said/'walking beam, said rchamber containing fluid at least part of which is gas, whereby the gas will be compressed and energy stored during one stroke of said walking beam and the gas will be expanded and energy delivered during the other stroke of said walking beam; a second stationary member; a second movable member actuated by said walking beam and associated with-said stationary member to provide a second chamber variable iri volume in response to the rocking of said walking beam, said chamber containing gas; means venting said second chamber whereby gas ywill be compressed vrive shaft is substantially equalized throughout v he stroke; and means manually operable for lreyenting movement of said counterbalanoing deans, said pump means and said storing means vhen the pump' plunger is disconnected from'the J, rank.

5. In an apparatus for reciprocating a pump lunger including a drive shaft and a crank, the :ombination of: meanscounterbalancing the re- :iprocating parts whereby the loads on the drive :haft on the up and down strokes of the plunger rre substantially equalized, s aid means including l. piston adapted for pumping liquid in a cylinder o compress a gas in a chamber; return means for eturning to the cylinder, from a body of liquid maintained in sealing relationship between said aiston and said cylinder, liquid which has escaped round said piston, whereby the volume of liquid n said cylinder and chamber is maintained sub- 4tantially constant; pump means, including an Juxiliary piston and cylinder, taking energy from he reciprocating parts only during their deceleraion by compressing a gas and delivering 4energy o the reciprocating parts only during their ac- 'eleration of the succeeding stroke by. expanding he gas, said auxiliary cylinder having a body of lubricant therein; a cup shaped member on the ower end of said 'auxiliary piston'dipping into `he body of lubricant at the lower end ofeach stroke, said member having openings therein or the discharge of a sealing lubricant film be- ;ween said member and the wall of said auxiliary :ylinder during travel of said auxiliary piston; neans storing energy when the'crank is near lead center position and delivering energy when he crank is farthest from dead center position whereby the load on the drive shaft is substantialy equalised throughout the stroke; and means manually operable for preventing movement of aid counterbalancing means, said pump means nd said storing means when the pump plunger s disconnected from the crank.

6. In an 'apparatus for reciprocating a pump lunger including a drive shaft and a crank, the nombination of: means counterbalancing the reiprocating parts whereby the loads on the drive haft on the up and down strokes of the plunger re substantially equalized, said means including only part of said one stroke of said walking beam wand the gas will be expanded in said second charnber and energy delivered during only part of the said other stroke; and means connecting said second chamber to said chamber for supplying compressed gas to said chamber whenever the pressure in said chamber falls below a predetermined value.

8. In combination: a walking beam; means for l pivotally supporting said walking beam; means for rocking said walking beam; pump means ina well; connecting means extending from said walk- Ling beam to said pump means whereby the rockmeans; a stationary member; a movable member connected to said walking beam and associated 4with said stationary member to close a fluidtight chamber variable in volume in response to containing a uid at least part of which is gas, whereby the gas will be compressed and energy stored during one stroke of said walking beam and the gas will be expanded and energy delivered during the other stroke of said walking beam; and means releasably connected to said movable member to prevent movement of said movable member when said connecting means is disconnected from said Walking beam. i heir deceleration by compressing a'gas and de# 9 In an apparatus fOIf TGCDIOCatng a Dump ivering -energy to the reciprocating parts only during their acceleration of the succeeding stroke by expanding the gas, said auxiliary cylinder communicating with said chamber whereby the quantity of gas in said chamber is maintained substantially constant, said auxiliary cylinder having a body of lubricant therein; a cup shaped member on the lower end of said auxiliary piston dip-- ping into the body of lubricant at the lower endof each stroke, said member having openings therein for the discharge of a sealing lubricant film between said member and the wall of said 1 auxiliary cylinder during travel of said auxiliary piston; means storing energy when the crank is near dead center position and delivering energy when the crank is farthest fromA dead vcenter position whereby the load on. the drive shaft is substantially equalized throughout the stroke;

combination of means counterbalancing the reciprocating parts whereby the loads on the drive shaft on the up and `down strokes of the plunger are substantially equalized, said means including a piston adapted for pumping liquid in a cylinder to compress a gas in a chamber; a-second piston reciprocable in a second cylinder formed in said piston and communicating with both sides of said piston; means associatedwith said cylinder and operating said second'vpiston during reciprocation of said piston whereby liquid is forced from said second cylinder into said cylinder to maintainl substantially constant the volume of liquid in said cylinder and chamber; pump means, including an auxiliary piston and cylinder, taking their deceleration by compressing -a gas and dethe rocking of said walking beam, said chamber plunger including a drive shaft and a crank, the

energy fromthe reciprocating parts only during and energy stored in said second chamber during ing of said walking beam actuates said pump by expanding the gas, said auxiliary cylinder having a body of lubricant therein; a cup shaped member on the lower end of said auxiliary piston dipping into the body of lubricant at the lower endof each stroke, said member having `openings therein for the discharge of a sealing lubricantv film between 'said member and the wall of said auxiliary cylinder during travel of said auxiliary piston; means storing energy when the crank is near dead center position and delivering energy when the crank is farthest fromA dead center position whereby the load on the drive shaft is substantially equalized throughout the stroke; and means manuallyoperable for preventing movement of said counterbalancing means, said vpump means and said storing means when the pump plunger is disconnected from the crank.

10. In a well pumping apparatus including a reciprocating member, the combination of: means substantially counterbalancing the Weight of the reciprocating member, said means including a primary member and a secondary member reciprocating with the reciprocating member and associated with said primary member to closea chamber variable in volume in response to the reciprocation of the reciprocating member, said chamber containing liquid and gas, whereby the gas will be compressed and energy stored during one stroke of the reciprocating member and the gas will beexpanded and energy delivered during the other stroke of the reciprocating member; means for supplying gas to said chamber to maintain the amount of gas therein substantially constant; and means for supplying liquid to/ said 'chamber to maintain the amount 'of liquid therein substantially constant.

11. In a well pumping apparatus including a 'reciprocating member, the combination of:

means substantially counterbalancing the weight of the reciprocating member, said means including a primary member and a `secondary member reciprocating with the reciprocating member and associated with said primary member to close a chamber variable in volume in response to Ithe reciprocation of the reciprocating member, said chamber containing liquid and gas, whereby the gas willbe compressed and energy stor'ed during one stroke of the reciprocating member and the gas will be expanded and energy delivered during the other stroke of the reciprocating member; means absorbing energy from the reciprocating member by compressing afgas near the end of the stroke of the reciprocating member and ap.

. plying energythereto by the expansion of the gas during the early part of the succeeding stroke of the reciprocating member, said means supplying gas to said chamber to maintain the amount of gas therein substantially constant; and means supplying liquid to said chamber to maintain the-V amount of liquid therein substantially constant.

12. In a well pumping apparatus including a nreciprocating pump plunger, the combination of means counterbalancing the reciprocating parts whereby the loads on the prime mover on thel two strokes of the plunger are substantially equalized, said means including a piston adapted tion of said piston whereby fluid is forced from said cylinder into said chamber to lmlntain subergy to the member during its subsequent acnecting said crank and said Walking beam where- `by the loads on the drive shaft on the up an therein; a cup-#shaped member on the`lowe stantially constant the amount of fluid in said chamber.

13.v In a well pumping apparatus for recipro cating a pump plunger and its connections, the combination of means counterbalancing the reciprocating parts including the pump plunger and its connections whereby the loads on the prime mover on the two strokes of the plunger are substantially equalized, said means including a piston adapted for reciprocation to compress a uid in a cylinder; and means for locking said piston against movement relative to said cylinder whereby the plunger and its connections may be disconnected from the apparatus without loss of pressure on the fluid, said means being manuallyl operable to move said piston during the connection of the plunger and its,r connections to the apparatus.

14. In a well pumping apparatus, the combination of: a prime mover; a member driven by said prime mover; a pump plunger in a well connected to and reciprocated by said member.; means counterbalancing said pump plunger and reciprocating parts whereby the loads on the prime mover on the up and down strokes of said pump plunger are substantially equalized; means absorbing energy from said pump plunger vand reciprocating parts during the later part of one stroke and applying energy to said pump plunger and the reciprocating parts during the early part of their succeeding stroke; means storing energy when said member is near thel end of its travel in one direction and applying energy thereto ywhen said member is near the middle of its travel in the opposite direction; and means for securing said rst mentioned means against movement.

15. In a Well pumping' apparatus including a reciprocating member, the combination of means storing energy from the reciprocating member during its deceleration and applying enceleration; and means for securing said first mentioned means against Waste of energy by movement during disconnection of the reciprocating'membe from the apparatus, said means being manually operable during such disconnection for movement to facilitate connection of combinationi of a prime mover; a drive shaft driven by said prime mover; a crank driven by said drive shaft; a Walking beam; means conby said walking beam is oscillated by the rotatio of said crank; a pump including a plunger; means connecting said plunger and said walkin beam whereby said plunger is reciprocated b the oscillation of said walking beam; mean counterbalancing the reciprocating parts WheredoWn strokes of the plunger are substantiall equalized, said means including a piston adapte for pumping uidin a chamber; return mean for returning to the chamber iluid which ha leaked therefrom whereby the amount of iluid i said chamber is maintained substantially con stant; pump meansrincluding an auxiliary pis ton and cylindervtaking energy from the recip rocating parts during their deceleration by com pressing a iiuid and delivering energy tothe re ciprocating parts during their accelerationysai auxiliary cylinder having a body of lubrican end of said auxiliary piston dipping into, th

ized throughout the stroke; and means for locking the apparatus in stationary position during vthe removal of said pump and connecting means from said walking beam.

1'7. The method of counterbalancing a vertically reciprocating pump plunger in a weil, which includes the steps of: applying force to the plunger throughout its downstroke resisting movement of the plunger, said force increasing with the travel of the plunger; applying force to the plunger throughout its upstroke assisting its movement, said force being substantially equal to the force resisting the plungers downward movement and decreasing with the travel of the plunger; applying an auxiliary force to the plunger during only the later part of its downward stroke resisting its movement, said force increasing with the travel of the plunger in that portion of its stroke in which such force is effective; and applying a force to the plunger substantially equal to the auxiliary force during only the early part of its upstroke, said force decreasing with the travel of the plunger in that portion of its stroke in which such force is effective.

18. The method -of counterbalancing a pump plunger vertically reciprocated in a well by the rotation of a crank, which includes the steps of: applying force to the plunger throughout its downstroke resisting movement of the plunger, said force increasing with the travel, of the plunger; applying force to the plunger throughout its upstroke assisting its movement, said force being substantially equal to the force resisting the plungers downward movement and decreasing with the travel of the plunger; applying force to the crank resisting its movement during its travel near dead center position, said force diminishing with the distance of the crank from such position; and applying a force to the crank substantially equal to the last named force assisting its travel in position farthest from dead center position, said force diminishing with the distance of the crank from such position.

WALTER E. SAXE.

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