Hydropneumatic pumping system

June 24, 1941.

2,247,238

D. JOHNSTON hydropneumatic pumping system

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June 24, 1941. _D Johnston 2,247,23$ hydropneumatic pumping system

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June 24, 1941.

2,247,238

D. JOHNSTON hydropneumatic pumping system

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June 24, 1941..

D. JOHNSTON hydropneumatic pumping SYSTEM .2,247,238

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June 24, 1941.

2,247,238

D. JOHNSTON hydropneumatic pumping system

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June 24, 1941.

2,247,238

D. JOHNSTON

HYDROPNEUMATIC PUMPING SYSTEM

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Patented June 24, 1941

2,247,238

UNITED STATES PATENT OFFICE

2,247,238

HYDROPNEUMATIC PUMPING SYSTEM

Douglas Johnston, Shelbyville, III., assignor to Leslie R. Tallman, Gentry L. Tallman, Emma S. Tallman, and Jesse D. Tallman, all of Shelbyville, III.

Application April 17, 1939, Serial No. 268,168

Claim. (Cl. 60—53) tank, connected at one side with the discharge from the motor and at the other side with the suction side of the hydraulic pump whereby, on the downward stroke of the working cylinder of the hydraulic motor, the discharge from the motor is forced into the balancing tank by the weight of the pump rod. This acts to compress the air in said tank, which thus stores the energy made available by the weight of the pump rod when lowering the same. On the upward stroke of the working cylinder, this high pressure air forces the oil into the suction pipe of the hydraulic pump, thereby lessening the load of the pump and preventing loss of energy in the sys15 tem, with the result that I secure very high efficiency in operation.

The disadvantages of a purely pneumatic system are high first cost of heavy, cumbersome equipment, and extremely poor efficiency due to 20 heating losses in compression. On the other hand, the disadvantages of a hydraulic system are that the fluid is non-compressible and therefore causes hammer and shock at medium and high speeds.

•25 By combining the two systems in a single unit in accordance with the principle of my invention, I obtain all the advantages of both systems and eliminate the disadvantages of each. That is to say, by using a hydraulic system in combination 30 with a small and inexpensive air compressor, enough air is injected into the hydraulic system to absorb shocks and provide for smooth, quiet operation. The quantity of air injected into the system is so small that the compressor losses have 35 a negligible effect upon the efficiency of the system.

In pumping oil wells, it is necessary to change the length of the stroke of the pump rod in accordance with the height of the oil in the well, 40 in order that the valve head on the lower end of the rod shall not engage and pound the oil in its downward stroke, which as known, produces very undesirable results. In pumping systems now employed, in which the pump rod is generally 45 reciprocated by a walking-beam, this necessitates a laborious operation and expenditure of considerable time, owing to the weight and size of the equipment.

It is one of the principal objects of my inven50 tion to provide simple means for changing the stroke of the working cylinder of the hydraulic motor, which comprises adjusting mechanism located on top of the unit capable of being readily turned in one direction or the other to determine 55 the movement of the motor sleeve which conThe general object of this invention is to provide a novel hydro-pneumatic pumping system for use, more particularly in pumping oil from wells, which shall afford a smooth-working, high speed and highly efficient pumping unit, and which shall combine the economy and efficiency of the purely hydraulic system with the smoothness and quietness of the purely pneumatic system.

In the embodiment of the invention, herein shown and described, I utilize as the main pumping element the hydraulic motor described and ilustrated in Patent No. 2,128,048, granted to me August 23, 1938. The motor as illustrated in said patent was embodied in the form of a tramper for use in packing cotton, and hence the power stroke was downward. In the present, as the motor must exert a lifting action, the power stroke is upward; hence, in its embodiment in a pumping unit, the hydraulic motor of the patent referred to is reversed in position from that shown in the patent, or turned upside down. Otherwise, the motor is identical in construction and operation, so far as the hydraulic feature is concerned, with that shown in my patent.

An important feature of the present invention resides in the fact that I utilize air under pressure to co-operate with the pressure fluid, or oil, in such manner as to balance the reciprocating action of the motor in both directions.

It will be realized that in the case of a well from one thousand to several thousand feet in depth, the weight of the pumping rod required is very great, and in the downward stroke would move the working cylinder of the motor downward with such rapidity and force as to produce a severe shock, and possible wreckage of the motor, if means were not provided for cushioning such downward movement.

On the other hand, most of the shock on a hydraulic pumping system occurs at the extreme end of the downward travel, just as the hydraulic motor reverses and starts upward, lifting the weight of the pump rod and the fluid; and there would be liability of a severe jerking action if the upward movement of the cylinder were not also cushioned.

To provide for this cushioning action, I so arrange the admission to the motor of compressed air with the oil that at all times the air will be present in the system to balance the action of the working cylinder and maintain the entire body of working fluid under pressure.

It is a further feature of the invention to provide means, preferably in the form of a balancing

2,2 trols the stroke of the cylinder, and which operation requires only a few minutes of time.

Other features of the invention, and various novel combinations of parts involved in my improved pumping system, will be set forth in the course of the description of the invention to follow.

In the accompanying drawings:

Figure 1 is a broken elevation view of the entire pumping system:

Figure 2 is a sectional plan view on the line 2—2 of Figure 1;

Figure 3 is a broken, elevational view on an enlarged scale, sectioned on the line —3 of Figure 1;

Figure 4 is a vertical sectional view,, broken away, and greatly enlarged, of the stroke changing mechanism, the housing of which is mounted on, and extends a considerable distance above the top of the derrick, as shown in Figure 1;

Figure 5 is an enlarged sectional plan view on the line 5—5 of Figure 1;

Figure 6 is a Cross-section, further enlarged, on the line G—6 of Figure 4, and viewed upwardly, as indicated by the arrows;

Figure 7 is a sectional plan view, further enlarged, on the line 7—7 of Figure 4.

Figure 8 is a longitudinal sectional view on an enlarged scale taken on the line 8—8 of Figure 11 through the piston and sleeve, the latter being in its lowermost position, and showing a portion of the working cylinder and of the hollow piston rod;

Figure 9 is a cross sectional view taken on the line 9—9 of Figure 8, and viewed in the direction of arrows;

Figure 10 is a view similar to Figure 8 but taken on the line ί 0-— i 0 of Figure 11 and viewed in the direction of the arrows;

Figure 11 is a cross sectional view taken on the line If—II of Figure 10 and viewed in the direction of the arrows;

Figure 12 is a central vertical sectional view on the same scale as Figure 8, taken on the line 12—12 of Figure 9 and viewed in the direction of the arrows;

Figure 13 is a cross sectional view taken on the line 12—12 of Figure 12 and viewed in the direction of the arrows;

Figures 14, 15 and 16 are views corresponding respectively, to Figures 8, 10 and 12, but showing in each view the sleeve in its uppermost position; _ Figure 17 is a cross sectional view taken on the line 17—Π of Figure 14 and viewed in the direction of the arrows; and

Figure 18 is a vertical sectional view on an enlarged scale taken on the line 18—18 of Figure 3 and viewed in the direction of the arrows.

Referring now particularly to Figures 1, 3 and 5 of the drawings, the numeral S indicates a platform secured on the upper ends of uprights 2, the lower ends of which are mounted on runners 3, these parts constituting a portable derrick of considerable height, and on which the hydraulic motor of the pumping system is mounted. The numeral 4 indicates the working cylinder of the hydraulic motor, on the lower end of which is screwed a flange -5 through openings in which extend lifting rods 6 having at their upner ends heads 7 by means of which they are supported in the flange 5. Below the flange 5 there is secured on the lower end of the working cylinder a stuffing box 8, having a gland 9, which works over the stationary hollow piston rod 10. The ',238 piston rod has secured on its lower end a circular plate 11 which is secured to and supported on an intermediate frame consisting of crossbars 12 connected at their ends to the uprights 2 and having secured between them I-beams 13. The numeral 14 indicates a pump rod, which is supported from and fixedly associated with the lower end of the lifting rod 5, in the following manner:

The numerals 15 indicate, respectively, two plates to each of which is welded on its inner side a jaw 16, which jaws are clamped about the upper end of the pumping rod by means of bolts 17. The plates 15 are carried by a cross-pin 18, 15 (Figure 3) which is supported in a saddle consisting of two beam-plates 19, between which are welded two plates 20 which are drilled for the lifting rods 6 to slide through. The lower ends of the lifting rods are screw threaded to receive 20 nuts 21, and between washers mounted on these .nuts and the saddle plates 29, are interposed coil springs 22. These springs afford a yieldable mounting for the pump rod support described and tend to eliminate the transmission of any shock 25 or jerk to· the pumping rod I®, which will sometimes cause fractures and breakage. However, while desirable, these springs are not essential.

The pump rod 14 works through a stuffing box 23 mounted on the end of a short pipe section 24 30 which is, in effect, a part of the stuffing box, and is connected to the upper end of a T coupling 25, in the lower end of which is screwed the upper end of the oil well production tube 26. Screwed into the side of the T coupling 25 is the produc35 tion discharge pipe 27, which conveys the pumped oil to a storage tank or pipe line. The numeral 28 indicates the casing, on which is mounted the usual casing head 29, on which is mounted, in turn, the support 30 for the tubing ⁴⁰ 26. Referring to the upper portion of Fig. 1, and to Fig. 4, the cylinder 4 has welded on its upper end a flange 31 to the underside of which is welded the upper end of a guide key 32, which passes through a guide casting 33 (Fig. 2) and at 4o its lower end is welded to a block 34, in turn welded to the lower end of cylinder 4. The purpose of the key 32 is to prevent the cylinder 4 from turning so that the lifting rods 6 will not rub against the I-beam supports.

⁵⁰ Mounted on the upper end of the cylinder 4 of the hydraulic motor is the stroke changing device, which embodies a short pipe section 35 having welded on its lower end a flange 36 which is bolted at 37 to· the flange 31 on the upper end 55 of the cylinder 4. The upper end of the pipe 35 is connected to a reducing coupling 38 which at its upper end is connected to the lower end of a pipe 39 of considerable elevation. On the upper end of the pipe 39 is mounted a stuffing box 60 40 through which projects a rod 41 having mounted on its upper end a crank handle 42. By turning the crank handle the stroke adjuster, of which the pipe 35, coupling 38 and pipe 39 form the housing, may be raised or 65 lowered. This housing for the stroke adjuster also provides space for an air chamber constituting one element in the pneumatic means for cushioning the operation of the hydraulic motor.

A description in detail of the stroke adjuster ‘° will be deferred until after a description of the hydraulic motor, as its purpose and operation may then be more clearly understood.

The pneumatic system comprises a prime mover, preferably in the form of a gasoline or ' electric motor 43, the shaft 44 of which is con2,247,238 nected by coupling 45 to the shaft 46 of a hydraulic pump 47 of any preferred construction. The shaft 46 is provided with a pulley 48 which by means of a belt 49 drives a pulley 59· on the shaft of an air compressor 51 of any preferred or conventional type. Leading from the hydraulic pump is a discharge pipe E2 which is connected with an inlet 53 located near the lower end of hollow piston rod 10. As will be later described, a discharge pipe extends from the piston of the motor through the plate or flange ί ί, welded on the lower end of hollow piston rod 10 and this pipe is connected by coupling 54 to a pipe 55 the other end of which communicates with a tank 56 toward the lower end thereof. This tank is of considerable height as compared with its diameter, and at its upper end is provided with an automatic spring-actuated release valve 57.

Near its lower end tank 56 communicates through a pipe 58 with the suction side of the hydraulic pump 47. As will later appear, oil and air discharged from the hydraulic motor is discharged from the pipe 55, into tank 06, the air separating from the oil and passing to the upper portion of the tank, or into the air space indicated by 59, and the oil collects in the bottom, of the tank, or in the oil space indicated by 60.

The air in space 5'9 is of course under pressure, and the valve 57 operates to permit the escape of excess air from the tank and thus maintains a balancing pressure of a certain definite, predetermined value.

This tank will be referred to hereafter as a “balancing tank.”

Leading from the air compressor 51 is a pipe 61 which, through a T-coupIing 62 and a pipe section 63 connected thereto, communicates with an air cushion chamber 64. The pipe 52 leading from the hydraulic pump is in two parts connected by a T-coupling SS, and a short pipe 66 is connected at opposite ends with this T-coupling 62. Chamber 84 alvzays contains a relatively large amount of compressed air supplied from the air compressor.

; In addition to the small quantity of cushioning air injected into the hydraulic fluid line on the high pressure side 52 of the pump, of which compressed air, as stated, a relatively large volume is maintained in the cushioning chamber 64, the chamber 39, provided on top of the hydraulic motor also holds a large volume of air under pressure, and this chamber is kept filled by reason of the fact that in the hydraulic motor, as well as in the chamber 64, the air separates out of the oil to keep this chamber filled. At the beginning of the upward stroke, the air in chamber 39 is compressed by the driving fluid and therefore acts as a further aid in providing a slow, smooth start. Even though the air compressor should, for any reason, be out of commission for several hours, the air chambers 39 and S4 would hold the air long enough to provide for a smooth operation of the motor.

From the foregoing it will be readily seen that the entire fluid system is kept under pressure, which is regulated by the relief valve 57 in the top of the balancing tank. The pressure in this balancing tank is maintained against the discharge line 55 from the hydraulic motor and this pressure is kept high enough to balance the weight of the pump rod 14 in order, as stated, to prevent a sudden drop of the working cylinder of the hydraulic motor, causing slamming and possible breakage. Since the compressor is constantly feeding air into the system, the relief valve 57 is constantly discharging air therefrom, and thus maintains the air in tank 58 at the exact pressure required, regardless of the fact that the temperature changes affect the density of the air.

I will now describe the hydraulic motor and its operations, in order that the co-operation therewith of the pneumatic arrangement, and the manner of changing the stroke of the piston, to be later described, may be better understood.

At its upper end the hollow piston rod 16, previously referred to, is secured to, or formed integral with, the lower end of a stationary piston 67. Slidably mounted on this piston is a sleeve 6S having a closed upper end 69. Piston rings 70 are interposed at intervals between piston 67 and sleeve 68. At its lower end the piston rod 10 is welded, as indicated at 71 (Fig. 18) to the circular plate i ( previously referred to.

The working cylinder 4 of the motor is mounted to slide up and down on the piston rod 10, and likewise has slidable and sealing contact with the sleeve 68. To this end, piston rings 72 are interposed between the working cylinder and the sleeve. The upper end of the working cylinder has welded thereon at 73 (Fig. 4) the flange 31 previously referred to. To prevent leakage between the working cylinder 4 and piston rod 18, there is provided on the lower end of the cylinder a packing gland 8 which is screwed on to the lower end of the cylinder and affords an. interior shoulder 75 surrounding the cylinder 10 and slidably engaging the same. At its lower end the stuffing box 74 is closed in the usual manner by a gland 9 secured on it by bolts 77, between which gland and the shoulder 75 is interposed packing 78.

Oil under pressure is admitted into the hollow piston rod 10 through the inlet 53 previously referred to, whence it passes upward through the inside of the piston rod. The oil discharges through a discharge pipe 79 (Figs. 8, 10, 12, 14, 15, 16 and 18), which extends upward through piston rod 10 to the piston 67, in the lower end of which it is screwed, as indicated at 80. The lower portion of pipe 79 passes through the circular plate 1S (Fig. 18) welded to the lower end of the piston rod, and to prevent leakage of the high pressure oil at this point, a packing gland 81 is provided, the casing of which is welded on to the underside of plate I!. Slidably mounted on piston 67 below sleeve 68 is a ring 82 (Fig. 14). Screwed flush by shoulder 75 of the stuffing box 55 8 against the bottom of the working cylinder 4 is a sleeve 83, The sleeve 68 acts as a valve to automatically change the flow of oil at each end of the stroke of the working cylinder so as to reverse its direction and keep it going continuously, 69 as fully explained in my prior patent. In the upward movement of the cylinder, sleeve 83 will engage the ring 82, which will in turn engage the bottom of sleeve S3 to move the sleeve upward, the ring 82 merely acting as an auxiliary plunger, 65 in connection with the sleeve 83, this arrangement being provided in order to prevent the necessity of having cylinder 4 move up so far that the packing 78 would be cut by the joint between piston rod 15 and piston 67. In each upward 70 movement of the cylinder, the sleeve 83 operates to push sleeve 68 up to its extreme uppermost position.

At its extreme uppermost position sleeve 68 will have opened an outlet to the upper inside, or 75 chamber, of the cylinder, which releases the pres4sure therein, allowing the high pressure oil being pumped into the lower chamber of the cylinder, located below piston 67, to lower said cylinder. As the cylinder reaches its lowermost position, the stroke changer, to be later described, will have engaged sleeve 68 and shifted it back to its extreme lower-most position, in which position it will have closed the outlet to the upper chamber and opened a passage for the high pressure oil to be pumped into the upper chamber, to raise the cylinder. At the same time, this same passage will allow the oil in the lower chamber to also flow into the upper chamber. Hence, the cycle of operation is completed and the cylinder starts up on the next cycle, raising the lifting rods 6. The arrangement of parts by means of which the foregoing operation of the cylinder is effected by the inlet of pressure oil to the piston, will now be described, referring to Figs. 8 to 18 inclusive of the drawings.

In its lower portion, the piston 16 is provided with a hollow portion, or chamber 85 (Figs. 8, 10 and 12), the wall of which is provided on opposite sides with ports 86, 87, and 88, 8S separated equal distances from each other. The sleeve 68 in the portion thereof occupied by the piston rings 72 divides the cylinder 4 into a lower chamber 90 and an upper chamber 91, and the ports 87, 89 communicate with the lower chamber 98 below the level of the bottom of sleeve 68 when the latter is in its lowermost position as shown by the figures referred to.

The sleeve 88 in its upper portion, that is in the part S Set thereof above tiie bearing portion containing the piston rings 12, is reduced in diameter . to provide an annular space 92 between its wall and the wall of the cylinder 4. Toward the upper end of this reduced portion the wall of the sleeve is provided with a port 93, which is located at such distance below the top 69 of the sleeve as · to be moved beyond the upper end of the piston 67 when the sleeve is moved to its extreme upper position so as to open communication between the upper chamber 9i, and a chamber 94 provided between the top 69 of the sleeve and the upper end of the piston 67, when the top of the sleeve is moved upward, or away from the upper end of the piston (Figs. 14 to 16). The piston 67, above the portion thereof containing the chamber 85 is is cored out to provide an outlet passage 95, the outlet pipe 79, extending through the chamber 85 at a distance from its wall, being screwed into the piston 67 at the lower end of the outlet passage 95, in a manner to form a continuation of said passage (Figs. 8 and 14). At the top of the outlet passage 95, the wall of said passage and the body of the piston is cut through to provide an enlarged or circumferential port 96 (Figs. 8, 9, and 12) which, when the sleeve 68 is in its uppermost position (Figs. 14 to 16) registers with a circumferential series of ports 97 formed in the wall of the reduced portion 68α of sleeve 68 at the bottom end thereof. When the ports 96 and 97 are in register they establish communication from the upper chamber 91 of the cylinder through the annular passage 92 to the outlet passage 95.

To provide for the passage to the upper chamber 91 of the cylinder of pressure oil passing through hollow piston rod ! 0 to the chamber 85 of the piston, the latter is provided with an inlet passage 98 extending longitudinally through the piston from the top of chamber 85 to- near the top of the piston where a port 99 is provided leading from the top of inlet passage 98 to the outer

2,247,238 sides of the piston (Figs. 10,12,15 and 16). When the sleeve is in its lowermost position as shown by Fig. 12, the port 99 of the piston is in register with the port S3 of the sleeve 68, previously referred to, which permits the pressure oil to pass directly from the chamber 85 through passage 98, ports 99 and 93, and annular passage 92 to the upper chamber S! of the cylinder.

In order to control the application of the presI sure oil effective within the chamber 94 of the sleeve, to permit, or prevent, the movement of said sleeve in the upward or downward movement of the cylinder, so that said sleeve may function at the proper stage of said strokes to close or open i the ports controlling the application of the pressure oil to the cylinder, the following construction is provided referring to Figs. 8 to 11 and Figs. 14, 15 and 17 of the drawings:

The piston IS is longitudinally cored from its upper end to near its lower end to provide a cylindrical bore 189, (Figs. 9 and 17) in which is slidably mounted a plunger-valve, indicated generally by the numeral 191. This plungervalve comprises, preferably as an integral structure, a plunger-rod ί 02, having at its upper end a plunger-valve 103; above this valve a reduced portion ί 04, and at the upper end of the portion 164 a small head-valve 195. The valves 103 and ί 05 divide the bore 180 into a lower valve chamber 186 (Figs. 14 and 15) and an upper valve chamber 107 (Figs. 8 and 10). Between the valves 103 and 105 the reduced portion 104 provides an annular intermediate valve chamber 168. The upper end of bore 100 is 'closed by a screw plug IQS. a small longitudinal bore 110 extending through valve ί 03, from end to end, thereof, serves to afford communication between the intermediate valve chamber ! 68 and the lower valve chamber 186 for a purpose to be presently described. The piston 67 is further provided with a cored hole 111 (Figs. 11 and 16) extending from its upper side, from the lower end of which ports 112 (Figs. 10, 14 and 15), lead into the intermediate valve chamber 198 whereby communication from sleeve chamber 94 through hole 111 and ports 112 with the intermediate valve chamber 108 may be established. From the intermediate valve chamber 163 ports 113 (Figs. 8, 9 and 12) communicate with the outlet passage 95. Leading from the upper valve chamber 187 are ports 114, which extend through the wall of said chamber (Figs. 8 and 14) and which, when the sleeve 63 is in its lowermost position, as shown in Fig. 8, are in communication with ports 115, extending through the wall of the sleeve, whereby communication may be established between the annular space 92 and said ports with the upper valve chamber 107. When the plunger-valve 101 has been raised, as hereinafter described, the ports 114 and 115 will be placed in communication with the intermediate valve chamber 1Θ8 and hence with ports 112, which movement of the plunger-valve occurs prior to the upward movement of sleeve 68. so that pressure oil from the upper cylinder chamber 9! may pass through the annular space 92, ports 115, 114, and 112, through cored hole Hi’ to the sleeve chamber 94, thus balancing the pressure on both sides of the sleeve. Hence, no resistance will be offered to the subsequent upward movement of said sleeve.

In order to maintain ths plunger-valve 181 in its downward position prior to the time it is moved upward by contact of sleeve 83 at the lower end of cylinder 4 with the slide-ring 82

2,347,238 diminished by the area of the plunger-rod ¢8. Therefore, the net area upward is equal to the area of said piston-rod. It follows that the force the cylinder will exert is equal to the area of 5 the piston-rod times the pressure developed by the pump.

On the upward stroke there are no outlets open. This feature of the invention reduces the quantity of oil needed to operate the motor. The 10 amount of oil required to force the cylinder 4 up is equal to the area of the piston-rod multiplied by the length of the stroke.

The plunger-valve 90 9 1s held in its lower position by high pressure oil passing through the 15 small port 9 96 to valve chamber ¢07, from the inlet port 98. At the same time pressure oil passes from the upper chamber 9 ( of the cylinder through annular space 92 and ports ¢¢5, ¢¢4 to said valve chamber. The intermediate valvechamber 108 is in communication with the cored hole 11 1 in the piston through ports 112 and with the outlet 95, through ports ! 13. Chamber 94 in the upper end of sleeve 68, communicates through cored hole ill in the piston ί 9, and ports 112 25 with the intermediate valve-chamber 168. This communication exists always. In this position, there is no pressure in the upper chamber 94 of sleeve 68. The lower plunger chamber 9 0S has zero pressure, since it communicates through port 1S Θ in valve 103 with intermediate valve chamber 908, which is in communication with outlet 95, through ports 9 9 3.

While pump pressure acts on the lower end of the plunger-rod 192 in piston chamber 95, since the area of this plunger-rod is less than that of valve 1Θ3, there will be a net force to hold valve ί 03, in its lower position.

As the cylinder 4 moves upward under pressure of oil in its upper chamber 91, the first event 40 occurs when sleeve 83 (Fig. 18) engages ring 82, which in turn engages plunger-rod ! 02 to move plunger-valve 101 upward. To facilitate this operation I preferably secure a bar 122 (Figs. 8 and 14) to the lower end of the plunger-rod by means 45 of a bolt 123. This rod extends clear through the walls of the piston chamber 85 into ring 82 to which it is secured (Fig. 13). The walls of chamber 85 are slotted to allow the bar ¢22 to move down and up, one of these slots being shown 50 in Fig. 14 and indicated by the numeral 124. Bar 122 will therefore be engaged at its opposite ends by ring 82 as the latter is moved upward as will be apparent from the inspection of Fig. 13. As the plunger-valve moves up, the valve 1 S3 will 55 cover ports 113 before the ring 82 is moved up far enough to engage sleeve 68 and head valve 195 will first cover and then uncover ports 9 94 to place them in communication with the intermediate valve-chamber S88 and ports 9 9 2. At this ₆₀ stage, i. e., with the plunger-valve raised to substantially the position shown in Fig. 14, but with sleeve 68 in the lowered position of Fig. 8, the high pressure oil In upper chamber 91 is in communication with the sleeve chamber 94 by means ¢5 of annular space 92, ports 115 and ! 14, intermediate valve chamber ¢08, ports 112, and cored hole 111. Therefore, the pressure inside chamber 94 is the same as outside and sleeve 68 will offer no resistance to toeing pushed up. The ring 82 now 70 engages the lower end of sleeve 68 and pushes the sleeve up moving port 93 beyond port 99 of inlet, passage 98, thereby closing port 99 and cutting off passage of pressure oil to the upper chamber 91 of the cylinder. The pressure on the upper 75 end of sleeve 68 both inside and out, is now the which in turn is adapted to engage plunger-rod 102, the small port i 16 is provided, which permits high pressure oil from the inlet passage 98 to enter valve chamber 107, and thus exert downward pressure on the top of the plunger-valve. (See Figs. 10 and 15.)

The portion of the piston 67 below the bearing portion thereof provided with the piston rings 70 is reduced in diameter and on this reduced portion is slidably mounted the ring 82, previously referred to. This ring is fluted on the outside to provide ports i i 7 (Figs. 8 and 13) to allow free passage of oil on the upward stroke of the cylinder from the lower chamber 90 to ports 86 and into the hollow portion, or chamber, 85 of piston 67. Mounted in a circular groove produced in the interior wall of sleeve 68 at its lower end is a stop ring 118 (Fig. 8) which also is adapted to slide upward upon the reduced portion of the piston. This reduced portion pro- 20 vides a circular shoulder I ¢9, which will serve to limit the upward movement of sleeve 68 when engaged by the stop ring ί 18.

In order to cushion the sleeve 68 at the extreme limit of its upward movement, in case the cylinder should be operated without pumping oil, I provide a port 120, best shown in Figs. 12 and 13, which port is relatively wide at its lower end, and tapers to a mere slit at its upper end. This port is provided in the wall of the inlet passage 30 98 and hence oil may pass through said port to the annular space 921 surrounding the reduced portion of the piston and closed at its lower end by stop ring i !8. As the sleeve 68 is moved upward, the gradually decreasing area of port 35 ¢28 offers increasing resistance to the expulsion of oil through said port by stop ring ¢¢8, and causes the movement of the sleeve to be slowed down.

The operation of the motor will now be described, first premising that Figs. 8, 10 and 12 and the sectional views, Figs. 9, 11 and 13, illustrate the position of parts when the cylinder ¢, sleeve 68 and plunger-valve ΙΘΙ are in their lowermost position; while Figs. 14, 15, 16 and 17 illustrate the position of parts when said elements are in their uppermost position.

Referring now to the first named figures of the drawings, with the ports in the position shown, oil under high pump pressure entering the inlet 53 passes up through the hollow piston rod 18 into piston chamber 85, through inlet passage 98, out of port 99 in piston, through registering port 93 in sleeve 68, along annular passage 92 between cylinder 4 and said sleeve, and into upper chamber 9i of the cylinder. At the same time, oil, under the same pressure, is flowing out of the lower chamber 90 of the cylinder through ports 86 and 88 into piston chamber 85 and in the same manner as described to the upper chamber 91 of the cylinder. Since on the upward stroke the high pressure oil is exerting pressure in both the lower and upper chambers of the cylinder, the force in the upper chamber tending to push the cylinder up and the force in the lower chamber tending to push it down, it will be seen that the net force available for pumping will be equal to the difference between the areas which are filled with oil in the lower and upper chambers. In other words, the force pushing the cylinder up will be equal to the pump pressure times the net area it acts against. The area the pressure acts against upward is the area of the inside of the cylinder, while the area it acts against downward is equal to the same area

Ό 2,i same as the lower end, and the sleeve is therefore “floating,” and only a slight force is required to move it up, which is only the amount of force required to overcome a small frictional resistance. Also, except for the small force needed at first to hold up the plunger-valve, as explained later on, the same force is available for pumping as was available at the beginning of the upward stroke, namely, the oil pressure times the area of piston rod 1 B.

The oil is now flowing only into the lower chamber 30, and no outlets are open. Therefore, this oil will move sleeve 68 up until port S3 in said sleeve opens chamber 94, Fig. 14, which affords another means of allowing the oil in chamber Si of the cylinder and chamber 94 of the sleeve 68 to communicate. In this movement of the sleeve, port ί 15 will be moved beyond port 114, closing the latter (Figs. 8 and 14). The upward movement of the sleeve 08 just described is permitted by the fact that the cylinder 4 moves upward simultaneously with the sleeve, but at a slower rate, since the cylinder area is larger than the area included in the sleeve annulus, and the cylinder moves up enough only to provide such additional volume as is displaced by the annular volume of the sleeve walls in its upward movement. Thus, as stated, the sleeve is floating, since on its lower end, chamber 85 and ports 117; inside of its upper end, chamber 94; and outside its upper end chamber 91, all pressures are the same, and equal to the pump pressure, disregarding a slightly greater pressure in the lower piston chamber 85 due to the frictional resistance offered to movement by the sleeve. The latter is now free to move up because there is no fluid pressure or mechanical obstruction holding it down. At this point the sleeve is merely a floating connection between the fluid in the lower and upper portions 9® and 91, respectively, of the cylinder. The oil pressure in the upper chamber is acting over the entire area of the inside of the cylinder, while in the lower chamber the same pressure is acting only over the area of the inside of the cylinder, less the area of the piston rod. Therefore, as before, the net force exerted by the cylinder is equal to the pump pressure times the difference between the area in the upper and lower chambers, which area is equal to the area of the piston rod. If, now, it be assumed that the sleeve 63 'does not move upward at this point, then the oil being pumped into the lower chamber 90 through hollow piston rod 10, will immediately increase in pressure and act on the lower annular end of the sleeve, forcing the sleeve up against the oil in the upper chamber 91 of the cylinder. This will cause the pressure in this chamber to rise equally (or nearly so) in amount to the rise of the pressure in the. lower chamber. However, the oil in the upper chamber 91 acts upward on the end of cylinder 4 on an area much larger then the annular area of chamber 90 of the lower end of the cylinder. Therefore, the cylinder will have a greater increase in force upward and will travel upward, increasing the volume of the upper chamber 91, allowing sleeve 68 to move upward. Finally, ports 97 in sleeve 68 (Fig. 17) are moved into register with port 96 in piston S7 to relieve pressure in chamber 91 by providing an outlet through annular pas- -_tsage 92, ports 97 and S6 and outlet passage 95.

At this stage, pressure both inside and outside of sleeve 68, including chamber 91 of the cylinder and chamber 94 of the sleeve, has been reduced to that in tank 56, and the sleeve has 7 )47,238 reached its uppermost position. The oil pressure in the lower cylinder chamber 99 will hold sleeve 68 up in this position and force the cylinder to proceed downward, the oil in the upper 5 chamber 91 being discharged.

At this point, it may be desirable to explain what holds the sleeve 68 in its lowermost position for substantially the duration of the upward stroke of the cylinder, since in both lower cham10 ber 90 and upper chamber 91 the pressures are equal and the friction of the cylinder tends to pull the sleeve up. This is best explained by assuming that sleeve 68 does rise, closing ports 99 and 93, and cutting off the admission of oil Into 15 the upper chamber 91. Now, as pressure oil is still being pumped, the immediate effect will be a sudden rise of pressure in the lower chamber 90. This rise in pressure in the lower chamber, when considered alone, will act against the area or) of sleeve 68, tending to push it up further. However, this pressure also acts against the bottom area of the lower chamber 90. This will naturally tend to force the cylinder down. The effect of this will raise the pressure of the oil 25 in the upper chamber 91. Of course, it will not raise it nearly as high as the pressure in the lower chamber. Now, chamber 94 of the sleeve has a pressure in it equivalent to that in tank 56, and as the area is equal to the area of the piston 30 67, the slight increase of oil pressure in the upper chamber 91 acts over a large area, unopposed by pressure from the other side. Always to be considered is the fact that the oil in chamber 91 acts against the area of the sleeve as well as that 35 area equal to the piston area. The areas are so proportioned that the pressure increase in the upper chamber, (due to the increase of pressure in the lower chamber acting upon the bottom of the cylinder) tending to push the sleeve down :o against the entire area of the inside of the cylinder, of which area an amount of area equal to the piston area, has no pressure at all acting on the other side, pushes down on the sleeve with a greater force than the force in the lower cham45 ber pushes up. The result is that the sleeve cannot rise, for as soon as it closes ports 93 and 99 slightly, a rise in pressure pushes it back.

I have heretofore referred to the small force needed at first to hold the plunger-valve 161 up 50 as the cylinder approaches the limit of its unward movement. An explanation of this will now be given.

As the completion of the upward stroke, the first event occurs when the plunger-valve closes 55 ports 113, thereby closing the outlet from the chamber 94. This requires a certain amount of force, which will have to be deducted from the force the cylinder will exert for pumping. However, as soon as ports 113 are closed and ports GO 115 begin to open, no force will be required to push the plunger-valve for the remainder of the upward stroke. The reason for this is that as soon as ports 113 are closed and ports 114 begin to open, the oil pressure in the intermediate 65 valve chamber 108 will be the same as the pressure-in the upper valve chamber 107, and through the port HO in valve 183 the lower valve chamber 106 will also have the same pressure. Since the pressure acting against the bottom of 0 plunger-rod 102 is equal to the same pressure as in valve chambers 106 and 107, all pressures will be the same and no force will be required to hold or push up the plunger-valve.

As soon as the cylinder starts downward the 5 high pressure oil communicating from cored inlet

S.247,238 7 turns in a nut 127 which is held down against the plate 36 by a coil spring 128 located within the pipe section 35 and held down by a tension nut 129 which is screwed into the upper end of pipe 35. The purpose of holding down the nut S27, with a spring is to provide a means to reduce shock when plate 125 on the adjusting screw engages the upper end of sleeve 68. The plate 36 and tension nut 129 are bored to permit the adjusting screw to slide through them. To prevent nut 127 from turning, it is provided with two slots 130 (Fig. 7) which work over keys 131, which are welded inside the pipe 35 near the bottom thereof.

The shaft 41 on the upper end of which a crank 42 is secured has welded on its lower end a plate 132, which in turn is welded into the upper end of a pipe section 133. Into the bottom of pipe 133, there are welded inside two short keys 134, (Fig. 6) which work in key-ways 135 milled in opposite sides of adjusting screw 126.

This means of turning the screw is provided in order to prevent leakage, such as would occur if the screw was extended through the stuffing box mounted on the upper end of pipe 39, which may briefly be described as comprising a centrally apertured plug 136 welded in the top of pipe 39 and through which the shaft 45 extends, welded on the upper side of which plug is a stuffing box 137, inclosing packing 138, and a gland 139 and closed by the cap 40, previously referred to.

The numeral 148 indicates a pin secured in the upper end of the adjusting screw to serve as a stop to prevent the adjusting screw from being screwed clear out of pipe 133, the engagement of the opposite ends of the pin with the top of tension nut 129, preventing this. The plate 36 secured on top of cylinder 4 is provided with apertures 141 and the nut 127 is provided with similar apertures 142, the purpose of these apertures being to permit air forced into the cylinder 4 with the pressure oil to pass upward through said apertures into the stroke changer housing 3E—38—89, which thus forms a pressure chamber, the compressed air therein acting to cushion the upward stroke of the cylinder. That is to say, each time high pressure oil is admitted suddenly into the chamber 91 of cylinder 4, instead of having this chamber filled with a noncompressable fluid, which would result in starting with a shock, the air in the upper part of said chamber, and the air in the stroke chamber housing, will compress like a spring under the pressure of the oil and provide resiliency, which will result in a slow, smooth, easy start. The operation of my improved hydro-pneumatic pumping system, will now be described.

Referring to Figs. 8, 10, 12 and 18, the sleeve 68 is shown in position for causing the upward stroke of the cylinder. Pressure oil is flowing in through inlet 53, through the hollow piston rod 10, piston chamber 85, through inlet passage 98 of the piston port 99 and sleeve port S3, which ports are in register. The oil flowing as described, contains bubbles of air due to the fact that the air compressor Si is continuously pumping a small supply of air through air compressor pipe 61 and air cushion pipe 60 into the pressure oil conduit 52. These air bubbles are compressible and provide the means of preventing oil hammer in the pipe lines. The air bubbles passing through the bottom of the cushioning chamber 64, being lighter than oil, rise up in the chamber to keep it filled with air at all hole 98 through small port 118 to upper valve chamber 107 will force the plunger-valve back into its lowermost position, or that shown in Fig. 8.

Since ports 114 and I! 5 are closed at this time, 5 this high pressure oil cannot run out of chamber 197 into the annular space 92 to the upper chamber 9 i and be wasted to the outlet. This is the reason ports i! 4 and 115 need to be closed. Also, when the plunger-valve moves down it pro- 10 vides an additional outlet from upper chamber Si, through the annular space 92, port 93, chamber S4, the cored hole Hi, ports S12, intermediate valve-chamber 108, and ports I i 3 to the outlet passage 05. However, when the sleeve is 15 shifted downward, ports 114 and i 15 will open before port 93 in sleeve 63 closes communication with chamber 94, which is connected to the outlet. Therefore, there will occur a momentary leakage of oil from inlet passage S3 through port 20 !! S to chamber i 07, through ports 114 and 1! 5, annular space ®2, port 93 to chamber 94, out through the cored hole 111, ports ! 12, intermediate valve chamber 108 and ports i 13 to outlet 95. This leakage will only be momentary as the sleeve 9,5 68 is moving down rapidly at this stage. Also port H 6 is so small that in the time available no appreciable amount of oil can flow through it.

With the plunger-valve in its lowermost position, as described, a means of escape of oil from 30 sleeve chamber 94 to outlet 95 is provided through the cored hole Hl, ports 112, intermediate valve chamber i 08 and ports H 3. As the cylinder nears its lowermost position, a circular plate 125 (Fig. 4) on the lower end of the stroke changer 35 engages sleeve 68 and lowers it. This movement of the sleeve is permitted by reason of the fact that the bottom of the cylinder is of larger area than that of the sleeve, as is obvious from an inspection of the drawings. Accordingly, if the 40 oil acts downward on a larger area of the cylinder than it acts upward on the sleeve, the cylinder will lower the sleeve, due allowance having been made for the weight of the cylinder. As the sleeve lowers, it will close outlet ports 96 and 45 97 and port 93 in said sleeve, which allowed upper chamber 9! another outlet through annular space 92 into sleeve chamber 94. The plunger-valve is still maintaining an outlet through this chamber, as explained above. 50 After the sleeve and cylinder have been lowered, in the manner just described, the parts will then be in the position as shown in Fig. 8 and the upward movement of the cylinder under the pressure of oil will be repeated in the manner 55 which has been described.

While, as I have stated, the elements of my hydraulic motor are reversed in position as respects the position of the parts illustrated in my prior patent, the operation of the hydraulic go motor is exactly the same in principle; and as the advantages of this particular· construction of hydraulic motor are fully set forth in my said patent, I deem it unnecessary to repeat the same, as said motor enters into the present invention 65 only as an element in a combination embodying pneumatic means for balancing and cushioning the operation of the motor.

The stroke changer, which I have referred to in general terms during the course of the 70 above description, will now be described in detail, referring particularly to Figure 4.

The numeral !2S indicates an adjusting screw having welded on its lower end the circular plate 125 previously referred to. This adjusting screw 75

2,247,238 times. Any momentary resistance, such as when sleeve 68 shifts, reversing the direction of the movement of cylinder 4, which causes a sudden increase of pressure against the oil flowing in pipe 52, will not cause hammer or shock, since 5 the oil from pump 41 will momentarily flow into chamber 64 and as stated above, the air bubbles in pipe 52 will compress. The above action will not only prevent any shock or hammer against the pump pipes, but it will at the same time io provide for a smoother stopping and starting of the hydraulic motor.

After the cylinder 4 has started up or down, the higher pressures of the oil necessary to accelerate the machine from a stop to full speed 15 having decreased, the air in the cushioning chamber S4 will expand, driving out the oil pumped in under the higher pressure, hence the cushioning chamber 64 will be ready again to receive a sudden supply of oil, due to suddenly in- 20 creased pressure, caused by stopping and starting the cylinder at the end of the sroke.

The pressure conduit 52 does not contain a large volume of air, since the compressor 5! is very small. Now if the conduit 52 were very long, 95 sleeve 83 engages plunger ring 82 shif ting plunger rod 182, and the valve sleeve 68, moving the parts into position shown by Figures 14, 15 and 16. Here the pressure oil is flowing into the lower chamber 08 of the cylinder, beginning the downward stroke. The oil in the upper chamber Si of the cylinder flows out through annular space 82, the ports 97 of sleeve 88 and 96 of the piston, as these ports are in register on the downward stroke. The air volume in the space (43 will gradually build up, driving the oil level (44 downwardly until the air begins to discharge through annular space 92, and ports 91 and 96 as mentioned above. At this level the air volume will > be maintained constant. Turning the stroke changer foot 125 up will decrease the air volume, while turning it down will increase the air volume. However, this variation of air volume is not detrimental to the action of the machine, since turning the stroke changer down, increasing the air volume, shortens the stroke; and with a constant speed hydraulic pump 47, this increases the number of strokes per minute in proportion to the amount the stroke is shortened. With a greater number of strokes per minute, a larger air volume say several hundred feet, and the hydraulic motor were operating at such a speed that the oil velocity in pipe 51 were high, then the air contained in pipe 52 would not be sufficient to cushion the hydraulic motor for smooth start- 30 ing and stopping, since the momentum of the high velocity oil in the pipe 52 would be sufficiently great to build up an extremely high pressure, if a resistance were momentarily built up against the inlet to the hydraulic motor, such as 35 is caused by suddenly stopping and starting. The air cushion 64 next to the pump, will be of diminishing benefit the longer the pipe 52 and the higher the velocity, since, as mentioned above, a long oil column moving at high speed 40 cannot be stopped suddenly without considerable shock. Therefore, it will be seen that it is necessary to provide an additional air cushion at, or preferably within, the hydraulic motor.

The upper chamber 9i of the cylinder and the 45 chamber of the stroke changer provided by the connected pipe sections 35 and 39 are utilized to provide such an additional air cushion.

As described above, the oil containing air bubbles is flowing into the upper chamber 9i 50 of the cylinder. The air bubbles rise to the surface around and above the plate, or foot, (25 of the stroke changer which, of course, is of less diameter than the interior of the cylinder, keeping the space 143 of the cylinder above the foot 55 (25, and the stroke changer chamber filled with air under pressure, this air passing through the apertures (41 in the flange or plate 36 and the apertures (42 in nut (27, these apertures affording constant communication between the inside go of the stroke changer and the space (43 of the cylinder.

The instant the oil begins flowing out of port 93 of sleeve 68 through annular space 82 to the upper chamber 9 (, either the cylinder must start 65 with a certain shock or else there must be something to cushion the action of the cylinder. This result I attain by means of the air in the space (43 which gives or compresses, affording a slow shockless acceleration. After the cylinder reach- 70 es a constant speed the pressure is reduced to normal operating pressure, and the air in space (43 and in the stroke changer chamber expands to the original volume. When the cylinder reaches the upper end of the stroke, the shifter 75 is more desirable than with fewer strokes per minute, since the reversals and accelerations are more frequent. On the upward stroke, the hydraulic motor does not discharge any oil, the oil in the pipe 79 not being in motion. However, at the beginning of the downward stroke the oil in the upper chamber 91 of the cylinder begins to discharge through annular space 92, and ports 96 and 87. In order to discharge oil, the oil in passage 7S must either be suddenly accelerated to a high velocity causing shock, or else something must “give.” Again the air in the space (43 and in the stroke changer chamber compresses to allow the oil in passage 79 to be accelerated slowly and smoothly. Therefore, it will be seen that at the beginning of both the upward and downward strokes the air in the space 143 and in the stroke changer chamber serves to cushion the action of the machine.

The oil discharging from passage 79 through pipe 55 to tank 56 has to flow against the pressure in said tank, maintained at the desired value by relief valve 5Ί. Since on the downward stroke the cylinder 4 is supporting a very heavy load (the weight of the pump rod 64), the hydraluic motor would drop with disastrous results were it not for the fact that by the pressure in tank 56 the oil discharging from the upper chamber 91 of the cylinder is held under a high enough pressure to insure that the force due to this pressure acting against the top of the cylinder will be sufficient to balance ths weight of the cylinder. Therefore, the pump rod is air balanced, and no weights are required to balance the rod load, such as are necessary with the conventional walking-beam type of pump. Also,, since the oil flowing into the tank 56 on the downward stroke compresses the air to an even higher pressure in uhe space 59 of said tank, the energy available in lowering the pump rod is “stored” in compressing this air, and is utilized to help raise the pump· rod and the oil lifted on the upward stroke. The reason that the high pressure in the tank 56, helps raise the weight is that by increasing the pressure on the inlet to the pump, the pump differential (difference between suction and discharge pressures) is reduced, thereby putting a lighter load on the pump and making it easier to drive.

While I have described and preferred to em2,247,238 ploy in connection with the pneumatic system involved in this invention, the hydraulic motor forming the subject of my prior patent aforesaid, it will be understood that so far as the broad idea of my invention is concerned the hydro-pneumatic pumping system herein described and now to be claimed, is not limited to this particular type of hydraulic motor, or to the particular construction herein described of said motor, but that the pneumatic feature of the invention may be combined with other types of hydraulic motors, if any such there be, capable in operation of affording the cushioning action to the reciprocating element of the motor, and the other advantages which I have herein set forth.