US2095708A - Pump plunger - Google Patents

Description

Oct. 12, 1937. J. N. MARTIN 2,095,708

PUMP PLUNGER Filed may 4, 1937 INVEN TOR. JOHN N. N 46 TIN ATTORNEYS.

Patented Oct. 12, ,1937

UNHTED STATES PATENT OFFICE 3 Claims.

My invention relates to pump plungers and particularly to plungers for use in deep well pumping against relatively high fluid heads.

In plungers of this type which have heretofore been used, composition packing rings are assembled in groups on a body or piston, each ring being separated from the next by a loose washer or spacer and the group held in place by an end nut. The failure or breaking down of any one ring removes the support for the adjoining ring so that it is no longer held to a proper pressure against the bore of the working barrel or cylin der. Another disadvantage common to these plungers is that the pressure of the fluid pumped against compresses the whole group of rings and spacers downward on the body in the ordinary working barrel installation, (or upward on an inverted insert pump), so that the end ring is highly compressed and worn out in a relatively short time. This sets a practical limit on the pressure against whichthis type of plunger will work, or the depth of the well which can be pumped by this means. Actual experience shows that after the failure of one ring, usually the bottom ring ofeach group on a traveling valve working in the ordinary working barrel, the other rings are quickly torn up.

" For use in pumping wells where the pressure is beyond the practical limit for composition packed plungers, pumps having all-metal plungers which fit very closely within the cylinder are used. There are two main objections to this type of pump. One is the deleterious effect upon the efliciency of the pump resulting from abra. sion of the plunger and cylinder surfaces due to sand particles which are usually present in the well fluids, and second, the relatively high cost of such pumps.

Therefore, one object of this invention is to provide a plunger, having composition packing rings, for pumping against pressures hitherto beyond the practical limits of such packing and to thereby provide a relatively low cost pump for deep well pumping.

A particular object of this invention is to provide a plunger body which is grooved to receive composition packing rings, either singly or in mutiple, so that each ring or multiple ring is firmly held in place without the use of removable spacers or compression nuts, and entirely independently of the adjoining rings.

Another object is to arrange the packing rings on the plunger body so that each ring offers its resistance to the slippage of fluid independently of any other ring.

A further object is to obtain greater wearing life from a group of packing rings by an arrangement whereby the failure of any one ring Other objects and advantages of my new invention will be evident from the following detailed description when read in conjunction with the accompanying drawing which illustrates one form of my new invention.

Fig. 1 is an elevation of a portion of a conventional working barrel from which a part of the wall has been broken away showing a sectional elevation of a plunger in accordance with this invention.

Fig. 2 is a sectional elevation of a plunger in accordance with this invention showing same removed from the working barrel.

Fig. 3 is a transverse sectional view of one of the composition packing rings before swelling has occurred.

Fig. 4 is a similar view of the ring after swelling to its normal working form.

Referring to the drawing, numeral 5 designates a conventional working barrel, in which is mounted a cylindrical plunger body 6, the outside diameter of which is slightly smaller than the bore 5a of barrel 5., therebyallowing plunger body 6 to slide freely within bore 5a. The upper end of body 6 is connected by threaded attachment to a conventionaltraveling valve cage 1 which is in turn connected to the lower end of a pump rod 8 by means of a collar 9. Body 6 has an axial bore l0 extending therethrough to permit passage of fluids through the body. A

conventional ball valve ll cooperates with an annular seat l2 which is mounted within cage 1, the valve H and seat I2 cooperating to open or close bore I 0 in accordance with the reciprocation of body 6.

Body 6 is provided'with a series of spaced circumferential grooves l3 which are substantially rectangular in cross-section and which are cut body 6 provides intervening metal lands I4,

which are also substantially rectangular in cross section and which are circular in transverse section, the diameter of the latter section being the same as that of body 6 from which the lands I4 are formed. Each face of lands I4 which form the sides of grooves I3, has an annular recess I cut therein which is of angular shape. The face of the recess I5 farthest removed from the axis of body 6 being substantially parallel to this axis and the opposite face sloping from the bottom of the recess in the direction of the adjacent groove.

Each of grooves I3 is fitted with a packing ring I6 whose normal cross sectional area is only very slightly smaller than that of grooves I3 and is of corresponding shape so as to fit closely therein.

Rings I6 are of split construction having a bias split I'I (Figs. 3 and 4) to permit mounting of the rings in grooves I3.

Packing. rings I6 are made of composition material which is adapted to swell in the presence of the fluid to be pumped and when pumping such fluid will swell sufficiently to protrude into recesses I5 and outwardly from grooves I3 toward bore 5a of barrel 5, and will therebypress against bore 5a to prevent slippage of fluid past the rings. In their unswelled condition, rings I6 are preferably flush or substantially so with the outer surface of body 6, as shown by the dotted lines in Fig. 2, thereby permitting the ready insertion of body 6 and rings I6 into bore 50..

When pumping fluids such as oil or a mixture of oil and water, packing rings I6 are preferably formed of such composition material as is used in rubber belting, that is, rubber and fabric composition which will swell in the presence of such fluid. When pumping water, other materials which have the characteristic of swelling in the presence of water, or beltingcomposition may also be used for this service by first assembling under-sized rings on body 6 and causing them to swell a pre-determined amount by immersion in oil and after the rings have swelled to the desired size, the plunger may be utilized for pumping water.

By providing packing rings which normally, that is before swelling, completely fill grooves I3, such rings when in contact with fluids producing swelling thereof, can swell only into recesses' I5 and outwardly beyond the outer edges of grooves I3 toward bore 5a. The protrusion of the material of rings I6 into recesses I5 forms annular ridges I8 on the sides of the rings adjacent to lands-I4 and ridges I8 will assume a shape corresponding to the outline of recesses I5 and will serve to anchor rings I6 in'grooves I3 against displacement by friction of the rings against the bore 5a. Since the extent of the swelling of the packing rings is limited by the sides of grooves I3, the major portion of such swelling will be in the direction of bore 50. and the degree of such swelling can be pre-determined for each packing material in relation to the fluid to be pumped so that a good pumping fit between the packing rings and bore So. will always be provided. At the same time swelling of the packing rings will conform in shape to the interior of grooves I3 and will also cause the rings to tightly fill grooves I3 and thus prevent leakage of fluid between the rings and the walls of the grooves, the protrusion -of rings I6 into recesses I5 assisting in this respect.

Ordinarily the clearance provided between body 6 and bore 60. will be from about one-sixtyfourth-inch to about one-thirty-second-inch, and packing rings I6 will be so cut, in accordance with their pre-determined 'swelling characteristics, that they will swell sufficiently only to bridge the clearance space between body 6 and bore 5a and provide a close sliding fit in bore 511.

By the above described arrangement, each packing ring I6 will be fully supported within body 6 by lands I4 entirely independently ofevery other ring and the pumping load will be divided between the several rings. Thus, even though one of the individual rings I6 may fail, the efficiency of the entire "group of rings will be relatively unaffected except that the remaining rings will have distributed on them that portion of the pumping load which was previously carried by the ring that had failed. The end tightening nuts, such as are at present used, will be eliminated by my arrangement, which instead will utilize independent packing rings which are self-tightening.

The plunger of my invention, arranged as above described, will pump against any desired pressure by providing a suitable number of packing rings, and will have all of the advantages of a composition packed plunger in combating sand abrasion and in conforming itself to any irregularities in the surface of the bore of the working barrel, while at the same time,. providing a plunger which is considerably lower in-cost than metal packed or all-metal pumps.

By provision of a body 6 which is relatively close fitting within barrel 5 and which is fitted with composition packing rings of, pre-determined swelling characteristics which permit the packing to swell sufiiciently only to form a good pumping fit in bore 50., only a very small area of each packing ring will remain unsupported by lands I4 and as a result, the rings will ofler very effective resistance to the fluid pressure against which the rings must move. Consequently, very little flexing of the rings will occur under pressure thus permitting the rings to retain their maximum sealing efliciency for relatively long periods of time. In order to further reduce any flexing tendency of the portion of the rings which is exposed to the pressure of the fluid, that is, the unsupported portion of the rings, the cross section of the grooves I3, and consequently of rings I6, is preferably made to approach a square. For example, groove I3 may be in the form of a rectangle in cross section, the horizontal sides of which are about five-sixteenths inch in length and the adjacent sides about one-quarter inch in length. Rings I6 will normally have approximately the same dimensions in cross section and after swelling may increase in length horizontally to abou eleven- -rings may be made with tongue and groove joints or with any other type of joint commonly used for such purpose.

It will also be understood that the lower end of body 6, which is shown in the drawing to be an internally threaded collar, may instead be of any other desired form for attachment thereto of a conventional valve cage or other pumping attachment.

What I claim and desire to secure by Letters Patent is:

1. In a pump of the character described, a barrel, a pump plunger arranged in the barrel and comprising a cylindrical body, rings rigidly united with said body and extending laterally therefrom, said 'rings being spaced apart and forming intervening grooves substantially rectangular in cross section, and packing rings mounted in said grooves and engaging said barrel, said packing rings being normally of a size and shape to substantially fill said grooves and characterized by their ability to swell when immersed in a fluid to be pumped so as to protrude a predetermined disin the said grooves being separated from each other by lands integral with the body portion of said plunger, each of said grooves being substantially rectangular in cross section, and packing rings mounted in said grooves and engaging said barrel, said packing rings being normally of a size and shape to substantially fill said grooves and characterized by their ability to swell when immersed in a fluid to be pumped so as to protrude a predetermined distance beyond the outer surface of the lands and into engagement with the barrel.

3. In a pump of the character described, a barrel, a reciprocating pump plunger arranged in said barrel and having a plurality of ring grooves formed therein, the said grooves being separated from each other by lands rigidly united with the body portion of said plunger, said lands projecting into close proximity to the inner surface of the-barrel and each land having substantially parallel upper and lower surfaces which extend to the periphery of the body, and composition pack ing rings mounted in said grooves and engaging the inner surface of the barrel, said packing rings being normally of a size and shape to substantially fill said grooves and characterized by their ability to swell when immersed in a fluid to be pumped so as to protrude a predetermined distance beyond the outer surface of the lands, and into engagement with the inner surface of the barreL'opposed surfaces of the lands being provided with means to interlock with the packing rings to hold them firmly in place.

JOHN N. MARTIN.

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