US2065020A

US2065020A - Packing device

Info

Publication number: US2065020A
Application number: US754244A
Authority: US
Inventors: John B Picard; John C Bush
Original assignee: Pure Oil Co
Current assignee: Pure Oil Co
Priority date: 1934-11-22
Filing date: 1934-11-22
Publication date: 1936-12-22
Anticipated expiration: 1953-12-22

Description

J. a. PECAED ET AL.

PACKING DEVICE Filed Nov. 22,

Patented Dec. 22, 1936 UNITED STATES PATENT OFFICE PACKING DEVICE Application November 22, 1934, Serial No. 754,244

10 Claims.

This invention relates generally to pistons of the type provided with a plurality of resilient packing elements and more particularly to pump pistons whose resilient packing elements are subjected to difierent fluid pressures during the pumping operation.

This is an improvement of the invention disclosed in the application Serial No. 711,970, filed February 19, 1934, and it may be conveniently applied, for instance, to pump pistons adapted for use in force and lift pumps and the like for pumping fluid from wells.

As herein illustrated, this invention is shown applied to a lift pump piston or a valve piston for pumping fluid from deep wells. This piston is sometimes termed in practice as a traveling valve and is adapted to reciprocate within a pump barrel by means of sucker rods which extendto the surface of the well and which are connected to asource of power from which they derive their motion. The working barrel is suspended in the well from the lower end of a string of tubing as a continuation thereof, and contains a standing or check valve at its lower end.

Fluid is drawn into the barrel through its check valve and is subsequently displaced bythe traveling valve as the latter descends in the barrel.

The fluid, such as oil, that is being pumped from deep wells generally carries sand in sus- 7 sure of the fluid being pumped as the valve moves upwardly. Experience has shown that under these conditions this cup wears rapidly so that it is unable to sustain the load and if there is a next succeeding cup it comes into service and is likewise subjected to rapid deterioration.

It is the principal object of this invention to distribute in pressure diiierential increments, the load created by the head pressure of the fluid being pumped between the packing elements so that one of them is not required to withstand the total pressure until it fails.

To this purpose this invention contemplates the provision of a piston, some of the packing elements of which are arranged to operate under a pressure difierential, thereby distributing the total pressure load over several packing elements which results in lengthening the life of said elements.

This object is conveniently accomplished by distributing the pressure over a plurality of packing elements and by means of a pressure differential efiective above and below each element, thereby imposing substantially the same proportions of the load on each of said elements.

The particular embodiment of the principles of this invention disclosed herein contemplates the regulation of the eilective pressure on each of the cups by the provision of a plurality of pressure controlled valves which operate in conjunction with the head pressure of the fluid being pumped to cause a portion of the total head pressure to be imposed upon each of said cups. This is attained by providing a plurality of differential valves arranged to regulate and then close passages connecting consecutive chambers which are exposed to the opposite sides of the cups and the working side of the last cup, thereby permitting only a portion of the total head pressure to pass to each succeeding cup by proportioning the pressure. on each side thereof, the last active cup being provided with its pro rata share of the total head pressure.

This is accomplished by the provision of a difierential valve which proportionably distributes the pressure on each side of its respective cup. The operation of these differential valves is obtained by the provision of a differential in the areas on said valves, each area being exposed to its respective side of the cups. The magnitude of the areas exposed to the working side of the cups is determined in accordance with the direction of the progression of the pressure distribution through the series of cups.

When the pressure efiective on the larger of the difierential areas is sufiicient to oppose and overcome the pressure effective on the smaller area, the valve is actuated by said pressure thereby proportioning the pressure exposed to each side of the packing elements or cups.

With this novel arrangement the differential valve controlling the sealing element, which is adjacent the pumping load, will permit sufilcient fluid under pressure to pass to the next succeeding differential valve until the last sealing element is reached through the last valve and the pressure on the low pressure side of the differential valves builds up sufficiently to close the valves consecutively in their reverse order until they are all closed. Each packing element is then exposed to a pressure diiierential of the fluid being pumped and the total pressure load is thereby distributed in pressure differential increments over all of the packing elements. The pressure differential on each packing element provided with a valve is a function of the differential areas of said valves.

These objects and advantages produce a. balanced piston which is effective in prolonging the life of the packing elements and an efficient and uniformly operating piston.

Other novel features and advantages will appear in the following description.

In the accompanying drawing, wherein the practical embodiment of the principles of this invention is illustrated,

Fig. 1 is a longitudinal view of a traveling valve, parts of which are in section and parts of which are broken away.

Fig. 2 is an enlarged view on the line 2--2 of Fig. 1, parts of which are in section and parts of which are broken away.

Fig. 3 is a cross-sectional view taken along the line 3- -3 of Fig. 2.

Fig. 4 is an enlarged detailed sectional view illustrating a step in the process of assembling the valve parts. I

Referring to the drawing, I represents the traveling valve arranged'to have relative reciprocation within a working barrel. I I is a valve barrel which is ordinarily provided with a uniform bore throughout its length and has a cup-shaped exterior annular shoulder I2 on one end and the external threaded portion I3 on the other end. Above the shoulder the perimetral surface of the barrel I I is formed with alternate cylindrical surfaces of different diameters; the diameters of the alternate surfaces being the same. The cylindrical surfaces I4 are of larger diameter than the cylindrical surfaces I5 and provide a finished surface on which the packing members I6 and spacing members I! are assembled. The intermediate surfaces l4 form an annular chamber I8 with the spacing members I1 and the shoulders defining the alternate cylindrical surfaces I4 and I5.

Each of the cylindrical surfaces I4, and a portion of the adjacent cylindrical surfaces I5 are slotted axially of the barrel I l, to form rectangular radial openings I9, the ends of which are arcuate in shape as shown at in Figs. 1 and 4.

Each of these slots I9 is arranged to receive a differential valve casing 2| having the general shape of a Woodruff key with the arcuate surface 22 arranged to seat on the surfaces 20.

The outer perimetral surface of the casings 2I is formed to match the differential character of the surface of the barrel wall as shown in Figs. 1 and 3. The casing 2| is drilled from one 'end forming a triplicate differential bore comprising the fluid pressure passage 23, the smaller cylinder 24 and the larger cylinder 25, axially aligned in the order named. 26 represents a differential piston having a portion of smaller diameter 21 which works in the cylinder 24; and a portion of a larger diameter 28 which works in the cylinder 25.

To enable these bores to be conveniently formed by drilling, the cylinder extends to the end of the casing 2I, and after the differential piston is inserted, is enclosed by a plug 29 whose outer end conforms to the contour ofthe casing 2|.

Adjacent the plug 29 the cylinder25 is provided with a pair of

radial ports

30 and 3| disposed at substantially right angles to 'each' other. This plug is provided with a conical nose portion 29' projecting into the path of the fluid passing from the port 3I to the port 39, and acts as a stop to limit the travel of the valve 26 so that the fluid may at all times pass between said ports and be exposed to the large diameter end 28 of the valve 26. The port 30 communicates with the annular space I8 previously described, while the port 3I communicates with the groove 32 cut longitudinally in the side wall of the body of the casing 2 I and connected at its other end by the radial port 33 with the interior of the cylinder 24 adjacent to its end farthest removed from the cylinder 25 and arranged to be opened and closed by the movement of the valve 26. The groove 32 is closed by the wall of the slot I9 to form a passage.

The other end of the bore 23 is connected by the radial-port 34 to the next adjacent annular space I8.

35 is a passage connecting the adjacent ends of the

cylinders

24 and 25 with the interior bore The outer end of said passage of the barrel II. is enlarged to form a seat for the ball valve 35, which opens towards said bore and which may be held from dislodgement by peening in the end of the passage. This valve provides for the positive escape of any fluid that may have leaked past-the differential pistons 26 and become trapped between the differential portions of the valve.

Between the ends of. the adjacent seats 29,

the outer wall of the barrel II is provided with transverse slots 36 forming a pair of lips 31 with the arcuate slots 20 as shown in Fig. 4 which, after the valve casings are inserted in the seats 20, are peened down against the beveled .ends of the casings 2|, as indicated in Fig. 1, thus holding the casings permanently in position relative to the barrel.

The packing elements I6 may be made of flexible material, such as leather, and are formed in this instance, into cup-shaped members having the central opening 38 arranged to fit the cylindrical surfaces I4. 39 represents upstanding skirts arranged to be forced outwardly to form a seal with the inner wall of the working barrel of the pump when fluid pressure is effective thereon.

The lowerends of the spacing members, or cup rings H are reduced in diameter in order that they may fit into the skirt 39 of the packing element I6 and press against the flange thereof to hold it in place. A portion of the perimetral surface of the ring I! is concave as at 40 to produce an annular chamber 4| with the skirt 39, and the bore of the working barrel when the piston is inserted therein. The upper portion of the perimetral surface of the rings I1 is cylindrical, as "shown at 42, and is provided with a slight clearance to prevent metal to metal contact when the piston is placed in a working barrel.

Thisclearance also forms a part of the chamberll.

43 represents a passage through the rings I! for connecting the chambers. I8 with the chambers 4I.

After the differential valves are assembled and secured in position on the barrel II, the packing elements I6 and the spacing rings H are assembled thereon, the first packing element being seated in the cup-shaped shoulder I2 of the barre] and the lower end of the first ring member is inserted therein. The next succeeding packing element is seated in the cup-shaped 'end or shoulder 44 of the first spacing ring and the second spacing-ring is inserted therein and so on until the last packing element is placed in position.

45 represents the lock nut whose inner bore is tapped to fit the thread l3. The lower portion of this nut is shaped similar to that of the spacing ring elements I! and the upper portion is hexagonally faced, as indicated at 46, so that a wrench may be applied thereto for tightening the packing elements.

41 represents a lock nut arranged to lock the check valve body member 48 on the barrel II. The lower bore of the member 48 is tapped to fit the thread l3 and its outer perimetral surface is faced hexagonally to receive a wrench thereon.

The upper portion of the member 48 is reduced in diameter and provided with the thread 49 arranged to receive the lower end of the pump rod.

The other end of the member 48 is bored to receive an annular ring, whose upper end is provided with the valve seat 5| arranged to receive the ball check valve 52, which checks any downward flow of fluid through the member 48 and the barrel II. I

This structure is, of course, singular to the specific traveling valve illustrated in the drawing. However the exact location or number of check valves in the traveling valve is irrelevant to the function and operation of the differential packing valve. Again, there are many applications of pistons in pumps and engines to which these differential packing valves could be applied and which are not designed to permit the passage of fluid therethrough.

The operation of the differential packing valves is effective only when there is a fluid pressure developed on the pressure side of the valve as shown herein. When the piston is arranged for service in a working barrel of an oil well for pumping oil therefrom, the check valve ball 52 is raised by the oil as the piston descends in the working barrel displacing the oil therein. When the piston reaches the end of its stroke and is reversed in its direction of travel, the oil above the check valve will develop a total head pressure which is exposed directly to the uppermost packing element and is transmitted through the passage 43 to the first annular chamber I8 from whence it is exposed to the end of the small diameter 21 of the "first differential piston 26 through the

passages

34 and 23.

If this piston is not already in its lowermost position, this total head pressure will force it down thereby uncovering the port 33 through which a part of the total head pressure is transmitted to the passage 32, the port 3| passing the end of the large diameter 28 of the valve 26, and the plug 29, through the port 30 into the second chamber I8 and through the passage 43 of the first ring member I! into the chamber 4|.

This cycle is repeated from the second chamber l8 through the second differential valve mechanism to the third chamber l8 and so on until the last packing element receives its proportionate amount of the total head pressure.

The first differential valve 26 will close when the force developed by the fluid pressure multiplied by the area of the large diameter end 28 is greater than the force developed by the total head pressure multiplied by the area of the small diameter end 21.

Whether or not the first differential valve will close before pressure is admitted to the last packing element is mainly dependent upon the viscosity of the fluid and its resistance to flow through the several passages and ports.

However, each valve will close before the total fluid pressure of the first adjacent packing member is transmitted therethrough by reason of the differential in the pressure exposed areas of the valves and these valves will hunt their final positions only after the fluid pressures on each side thereof are a function of this differential factor.

In this manner, the total fluid pressure exposed to the piston may be distributed proporti'mately between the packing elements thereby demanding that each packing assume a portion of the total load which produces less wear and longer life for these elements.

This invention provides a positive method of distributing pressures and it is obvious that bycontrolling the areas of individual differential pistons known pressures may be controlled and directed to each packing element when the total p ston pressure is known.

Again this invention is applicable to double acting pistons where it is desirable to control the pressures on the several packing elements from each side thereof.

We claim:

1. In a piston arranged for relative reciprocation in the bore of a cylinder, the combination with a. plurality of annular packing elements mounted in series; .on the piston to collectively effect a fluid actuated seal, of differential valve means in said piston arranged to admit a portion of the pressure imposed on the piston between said packing elements.

2. In a piston arranged for relative reciprocation in the bore of a cylinder, the combination with a plurality of annular packing elements mounted in series on the piston to collectively effect a fluid actuated seal, of differential valve means in said piston arranged to admit a portion of the pressure imposed on the piston between said packing elements to require each packing element to assume substantially equal parts of the, total pressure.

3. In a piston arranged for relative reciprocation in the bore of a cylinder, the combination with a pair of annular packing elements mounted in series on the piston to collectively effect a fluid actuated seal, of differential valve means in said piston having differential areas exposed to each side of one packing element arranged to be operated by the total pressure.

4. In a piston arranged for reciprocation in the bore of a cylinder, the combination with a pair of packing elements mounted in series on the piston to collectively effect a fluid actuated seal, of differential valvular means communicating with the perimetral surface of the piston at either side of the foremost packing element and arranged to distribute the total pressure imposed on the piston proportionately between said packing elements.

5. In a piston arranged for reciprocation in the bore of a cylinder, the combination with a plurality of packing elements mounted in series on the piston to collectively effect a fluid actuated seal, of a plurality of differential valvular means communicating with the perimetral surfa e of the piston on either side of individual packing means and arranged to distribute the to al pressure imposed on the piston proportionately around the several packing elements.

6. In a piston arranged for reciprocation in the bore of a cylinder, the combination with a pair of packing elements mounted in series in the pistonto collectively effect a fluid actuated seal, M

' total pressure imposed upon the piston.

8. The combination of a member having a cylindrical bore, a second member within said bore, a plurality of annular packing elements mounted in spaced relation on one of said members and arranged to be actuated by a fluid pressure to seal against the other of said members, and differential valve means in one of said members associated with said packing elements for dividing the fluid pressure among said packing elements to produce a seal between said memhera 9. The combination of a member having a cylindrical bore, a second member within said bore, a plurality of annular packing elements mounted in spaced relation on one of said members and arranged to be actuated by a fluid pressure to seal against the other of said members, the member carrying said packing elements having means for admitting fluid pressure to said packing elements, and differential valve means in said last mentioned means for dividing the fluid pressure among said packing elements.

10. The combination of a member having a cylindrical bore, a second member within said bore, a plurality of annular packing elements mounted in spaced relation on one of said members and arranged to be actuated by a fluid pressure to seal against the other of said members, one of said members having means providing a fluid passageway and also having ports extending laterally from said fluid passageway to each of said packing elements, and a differential valve in said fluid passageway between said ports for dividing the fluid pressure among said packing dents.

JOHN B. PICARD. JOHN C. BUSH.