US2493341A - Apparatus for pressuring air counterbalance cylinders - Google Patents

Description

Jan. 3, 1950 w. G. COREY 2,493,341

APPARATUS FOR PRESSURING AIR COUNTERBALANCE CYLINDERS Filed Aug. 2, 1948 2 sheets sheet 1 FIG. I WILLIAM QCQREY lNl ENTOR A 7' TORNEV Jan. 3, 1950 w. G. COREY 2,493,341

APPARATUS FOR PRESSURING AIR COUNTERBALANCE CYLINDERS Flled Aug. 2, 1948 2 Sheets-Sheet 2 2/ as m Fl 6. 2

w w M |||||1 1 Fa i'iu' 33 7 a7 a? 57 WILLIAM G. COREY A fron/vgr Patented Jan. 3, 1950 UNITED STATES PATENT OFFICE APPARATUS FOR PRESSURING AIR COUNTERBALANCE CYLINDERS William G. Corey, Altadena, Calif.

Application August 2, 1948, Serial No. 42,104

3 Claims. 1

This invention relates tothe pumping of deep wells with the use of an air counterbalance, and in particular to means for supplying the counterbalance cylinder with make-up air and for repressuring the cylinder after periods of inactivity during which the pressure normally carried in it is vented.

A purpose of the invention is to permit the compressor supplyingv air under pressure to the cylinder to be driven by the prime mover by which the beam is activated, both with the beam in motion and with the beam idle.

A purpose of the invention is to provide automatic means for inactivating the compressor when the pressure in the air cylinder reaches a predetermined level.

In the operationof an air-balanced pumping unit, as described for example in the patent to Brett, l,624,52'1,'which is continuous over long periodamake-up air is required at intervals to replace leakage. The quantities so required are very small and a correspondingly small compressor is required. But when the unit is shut down, as for example to pull rods, the pressure within the cylinder may leak off, or be vented completely before the unit is again put into service, and before again starting the well pump the cylinder must be recharged to its original pressure. To save loss of pumping time, which is highly valuable, it is desirable to recharge as rapidly as possible, and thus a large delivery of compressed air for a'short period is needed.

While numerous devices for providing makeup and repressuring air have been proposed, the only one which has come into general use is that shownin the Brett patent and in many others of later date. In'these devices a single acting, reciprocating compressor has one of its elements coupled to and moving, with the beam and the other element coupled to a fixed object, the compression stroke being produced by the downward movement of the beam. As such compressors stroke continuously so long as the beam is in operation, it is customary to provide means for unloading thennaszby lifting: the intake valve from its seat, when the desired cylinder pressure has been reached.

This device may be so designed as to give satisfactory service in supplying the small amount of make-up air required to offset leakage, but whenmade of suflicient size to repressure the empty cylinder within a reasonable time, it becomes cumbersome, costly and difficult to maintain because it idles the greater part of the time.

The main drawback, however, to the use of any beam-operated compressor is that the beam must be operated in order to operate the compressor. This requires that the counterbalance cylinder be valved off so as not to create excessive loads on the unit as the system pressure approaches the required counterbalancing pressure. Or, by a complicated arrangement of piping and valves the counterbalance cylinder is converted into an auxiliary compressor to help the repressuring operation. The resulting long time, single-stage compression generates excessive heat and, in the necessary presence of lubricating oil, often causes the explosion of oil vapors in the cylinder, with hazard to machine and operators alike.

In the apparatus of the instant invention, a small independent compressor is driven at a relatively high speed from the prime mover during the pumping up period, the beam being then disconnected; the beam is reconnected only after the cylinder is fully repressured and its counterbalancing effect reestablished; the compressor operates at a lower speed for providing make-up air, and automatic means are provided for disconnecting the compressor from its drive when the desired pressure is reached.

The invention may best be understood with ref erence to the attached drawings and the following' description thereof, in which Fig. l is an elevation of an air balanced pumping unit (a portion of the counterbalancing cylinder being shown in section) showing the relative arrangement of parts with which the invention is concerned, and

Fig. 2 is a detail on an enlarged scale of the drive from prime mover to reducing gear and air compressor.

Referring first to Fig. l, foundation members ill support samson posts H which are braced against overturning as at l2. A beam !3 is pivotally supported as at M and is reciprocated around this pivot point by cranks it and p-itmans i6, only one of each showing in the figure. The outer or right-hand end of the beam is provided with a horsehead and cable, not shown, or other meansv for attaching the pump rod string to the swinging end of the beam.

The cranks are powered by any preferred prime mover, as for example the gas engine suggested at IT. This engine has a pulley [8 driving a corresponding pulley !9 mounted on the high speed shaft of a speed reducer 20, as through a plurality of V-belts 21.

A counterbalance cylinder 22 is swingingly attached to the beam as at 2%, this cylinder having a Working barrel 2'4 and a piston 25-. The piston speed shaft 3| of the reducing gear.

is mounted on a hollow piston rod 26 closed at its lower end as at 21 and swivelling in a cupped socket 28.

An air cushion maintained in the cylinder at a suitable pressure counterbalances the weight of the rod string plus approximately one-half the weight of the oil column in the pump tubing, thus equalizing the power load between the upstroke and the downstroke of the beam. Air is admitted to the cylinder, to offset leakage and for the purpose of repressuring, conveniently through a flexible tube 29 connected with the lower end of the hollow piston rod. A valve-controlled vent 29A permits the pressure in the cylinder to be reduced or released as may be required.

To this point the description is of an apparatus in common use, this description providing merely the environment in which the novel combination of elements next to be described is utilized.

Referring now to Fig. 2, a drive plate 30 is nonrotatably mounted on the outer end of the high Pulley I9 is provided with a plurality of grooves for the main drive belts 2| and with ordinarily a single groove for a V-belt 32 which drives an air controlled clutch generally indicated at 33 and through it an air compressor 34 which is preferably a conventional two-cylinder unit compressing in stages. Pulley I9 is mounted to rotate freely on shaft 3|, as on roller bearings 35, and drive plate 30 is keyed to the shaft as at 36.

The drive plate is provided with a plurality of readily removable studs 31 which project into registering holes in the web of pulley 19. With these studs in position the pulley is keyed to the drive plate and actuates the beam, while with the studs withdrawn the prime mover may be used to drive the compressor without actuating gear set, cranks and beam.

This simple arrangement of drive plate and studs is the functional equivalent of a jaw clutch, which may be substituted if preferred.

The clutch through which compressor 34 is driven must be of a type which is engaged and disengaged by changes in air pressure, and must further be so arranged that the clutch is engaged when the air pressure in the cylinder is low or atmospheric and disengaged by rising air pressure. A suitable form for this clutch is generally indicated at 33 and will now be described, it being understood that this detail is illustrative only.

An enlarged projection of the compressor crank shaft 38 is extended through a U-frame 39 in which it is carried on antifriction bearings 40 and 4!. A clutch spider 42 carrying on its face a ring of brake lining 43 has a hub 44 slidable lengthwise on the shaft. The hub is prevented from rotating on the shaft by a through-pin 45 passed through a diametric slot 46. The hub is constantly urged to move to the limit of its travel by a relatively stiff coil spring 41 bearing against a collar 47A which is fixed to the shaft.

The end of the shaft distant from the compressor is drilled centrally to receive a plunger 48 of which one end bears against pin 45, the other end carrying a disc 49 on which bears a cup leather or other piston 50. The cup is slidable within a short, closed-end cylinder and is held in contact with the disc by a relatively light coil spring 52.

A V-belt pulley 53, having a groove for belt 32, is mounted to revolve freely around shaft 38, as on radial-thrust bearings 54. The side of this pulley directed toward brake lining ring 43 is '4 faced smooth. The pulley is coupled to main drive pulley I 9 by belt 32 (shown as broken because of limitations of space) and rotates continuously, in a fixed longitudinal position on shaft 38, so long as the prime mover I! of Fig. 1 is in operation.

The compressor, which is indicated only in outline at 34, discharges into a relatively small air accumulator 55, from which the flexible tube 29 conducts air under pressure into hollow piston rod 26 and thus into the cushion space within counterbalance cylinder 22. Anarrow conduit 56, preferably containing in its length a balanced pressure valve 51, places accumulator 55 in communication with the space in cylinder 5| above piston 50.

Thus connected, when the pressure in the accumulator rises to a predetermined level, the piston 50, disc 49, plunger 48 and spider 42 are forced inwardly, carrying the friction ring 43 out of contact with the face of pulley 53 and effectively disconnecting the compressor from its drive. When the pressure again falls, spring 41 returns the friction ring into contact with the constantly revolving pulley and the compressor is again actuated. This arrangement must not be reversed as it is essential to repressuring that the compressor be coupled for actuation when there is no pressure in the air system.

The purpose of the balanced pressure valve 51 is to ensure sharp opening and closing of communication between the accumulator and the clutch cylinder, thus avoiding slipping and burning of the engaging members. This valve is an article of commerce and needs no description.

The combination above described, of a manually controlled clutch between the speed reducer and a pulley constantly rotated by the prime mover, with a pressure-responsive clutch between an independent air compressor and a pulley constantly rotated by the prime mover, has material advantages over previously disclosed arrangements for providing make-up air and repressuring.

For example, the beam is idle during repressuring and thus it is not necessary to disconnect the well load from the pumping unit to repressure the balancing cylinder. Taking the compressor drive from the prime mover avoids the necessity for a separate engine or motor to drive that element. As the beam is idle during repressuring the prime mover may be speeded up, if desired, to drive the compressor at its maximum permissible speed and thus the repressuring may be accomplished in a brief time even with a small and inexpensive compressor. Conversely, a small compressor may be operated at high speeds for short periods without damage or undue wear, and as the provision of make-up air requires the operation of the compressor for only brief and widely spaced periods, the provision of the automatic clutch which completely disconnects the compressor from its drive during the intervals between these. periods of demand reduces the wear on this element in pumping service to almost negligible. Repressurizing the system with an independent two-stage compressor eliminates the hazard of dieselizing.

Finally, except for the manual disconnection of the reducing gear from the main drive for the purpose of repressuring the operation of the system is entirely automatic. When repressuring is completed the compressor stops. The prime mover is then stopped long enough to replace the studs in the drive plate, or to engage an equivalent jaw clutch, and to attach the pump rod string to the swinging end of the beam. On again starting the prime mover, pumping begins and the compressor comes into operation only as small quantities of air are required from time to time to maintain the pressure in the counterbalancing cylinder.

I claim as my invention:

1. Apparatus for providing make-up and repressuring air to the cylinder of an air-balanced deep well pumping unit actuated by a prime mover through a speed reducer, comprising: a pulley revolving freely on the high-speed shaft of said reducer; manually operable means for locking said pulley to said shaft for synchronous rotation; an air compressor having a pulley mounted to revolve freely on an extension of its crankshaft; a belt connecting said pulleys for synchronous rotation; a conduit connecting the discharge of said compressor with the interior of said counterbalance cylinder, and clutch means responsive to the pressure in said conduit for locking second said pulley to said crankshaft for synchronous rotation, said clutch means being so arranged as to render said compressor operative when the pressure in said conduit falls below a predetermined level and to render said compressor inoperative When said pressure reaches said level.

2. Apparatus for providing make-up and repressuring air to the cylinder of an air-balanced deep well pumping unit actuated by a prime mover through a speed reducer, comprising: a pulley driven by said prime mover and normally driving said speed reducer; manually operable clutch means between said pulley and said reducer for rendering said speed reducer inoperative while said pulley continues to revolve; an air compressor having a crankshaft and a drive from said pulley to said crankshaft; a conduit connecting the discharge of said compressor With the interior of said counterbalance cylinder, and clutch means interposed between said crankshaft drive and said crankshaft and responsive to the air pressure in said conduit to disconnect said drive from said crankshaft when the pressure in said conduit reaches a predetermined level and to reconnect said drive with said crankshaft When said pressure falls below said level.

3. Apparatus for providing make-up and repressuring air to the cylinder of an air-balanced deep Well pumping unit, comprising: a compressor having a crankshaft; a pulley rotatable around said crankshaft; a speed reducer having a drive shaft and a pulley rotatable therearound; an automatic clutch responsive to the air pressure in said cylinder arranged to lock first said pulley in driving relation with said crankshaft when said air pressure falls below a predetermined level, and manually operable means for connecting second said pulley in driving relation With said drive shaft.

WILLIAM G. COREY.

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

UNITED STATES PATENTS Number Name Date 1,624,577 Brett Apr. 12, 1927 2,117,716 Gordy May 17, 1938 2,269,787 Saxe Jan. 13, 1942

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