USRE22054E

USRE22054E - Slush pump mston

Info

Publication number: USRE22054E
Authority: US
Publication date: 1942-03-24

Description

March 24, 1942. c, SHARP E'TAL Re. 22,054

SLUSH UMP PISTON Original Filed Nov. 29, 1955 2 Sheets-Sheet 1 DUDLEY C. SHARP 56 RANALDH.G nmszgg W 5. W F" March 24, 1942. D. c, SH RP ETAL Re. 22,054

SLUSH PUMP PISTON Original Filed Nov. 29, 1935 2 Sheets-Sheet 2 DUDLEY G. SHARE RANAwMGARmsoN.

Reissue d Mar. 24, -1 942 UNITED STATE PATENT OFFICE sLUsn PUMP PISTON Dudley C. Sharp and Ranald M. Garrison, Houston, Ten, assignors to Mission. Manufacturing Company, Houston, Tex., a corporation of Texas Original 2,189,839, dated February 13, 1940,

Serial No; 52,086, November 29, 1935. Application for reissue January 21, 1941, Serial 9 Claims.

The invention relates to an improvement in slush pump pistons of the type which are used in maintaining a circulation of the slush, drilling mud, or fluid in the rotary system of drilling wells.

Slush pump pistons of this type are subjected to pressures of several thousand pounds per square inch on the working stroke and to a sue-- tion or somewhat of a vacuum on the return stroke so that it seems obvious that they must be constructed to withstand enormous stresses and reversal of pressures as well. These pistons operate at a relatively high rate of speed in a close fitting liner with a highly abrasive liquidthe liner when subjected to pressure and draw away fromthe liner when subjected to suction.

Another object of the invention is to provide a packing element for slush pump pistons which is held in position on the piston body so that it may draw away from the liner on the suction stroke to eliminate wear and flex back against the liner on the pressure stroke in order to provide a seal.

It is also an object of the invention to provide an excess pressure area to receive the packing as it flows from its normal position due to either pressure or suction.

Another object of the invention is to provide a packing member for slush pump pistons which ,will be held in position so that it may seal against is securely confined in operating position but position on the supporting structure in such a manner that expansion or sealing of the packlog member can be accommodated without af-' 'fecting the operating of the piston.

It is also an object. of the invention to provide a clamping plate for slush pump piston body which supports the packing at one point and allows it to flex at another point.

Another object of the invention is to reeniorce the resilient material adjacent the area of greatest pressure so that it will be restrained from undue expansion.

Other and further objects of the invention will be readily apparent when the following description is considered in connection with the accompanying drawings wherein:

Fig. 1 is a side elevation of a slush pump piston arranged on its supporting rod with certain parts shown in section to illustrate the construction-and arrangement thereof.

Fig. 2 is a view of one of the locking rings used to hold the packing body and retaining plate in position.

Fig. 3 is a broken sectional view of a slightly modified form of the packing member.

Figs. 4 and 5 are a section and elevation respectively of a modified form of the piston which allows for swelling or expansion of the packing.

Figs. 6 and '7 are modified sections of two other forms which the invention may take.

Slush pumps of the general type now in use embody a rod 2 which is reciprocated by a suitable source of power. This rod is arranged to reciprocate inside of a pump liner which receives the piston 3. Some rods are of uniform diameter and receive the piston that it is locked in position by nuts l-while others are formed as here shown with a tapered portion 5 thereon which receives the piston so that it is securely wedged in position and held in that position by the nuts 4.

The present piston includes the body or hub 1 which has a tapered opening 8 therein to receive the tapered portion 5 of the rod 2. This hub is usually a metallic structure and is here illustrated as having a flange l0 thereon which projects outwardly from the hub to serve as a support for the packing elements I! and I3, one of which is disposed about each end of the hub on opposite sides of the flange l0. Theconnection between the flange and the hub is preferably rounded at It and the packings I2 and 13 are similarly formed so that a close contact will be had along the surface ii of the hub and the surface [6 of the flange.

The packings i2 and iii are identical and are hub.

against, the faces I8 of the flange. The outer periphery of these packings ispreferably concaved slightly from the outer lip 22 toward the base 20 so that the lip 22 is slightly oversized with respect to the inside diameter of the liner in which it is to be confined. Inthis manner the inherent resiliency of the material 23 of which the packing is made will tend to force the lip 22 against the liner to prevent abrasive particlesfrom flowing beneath the liner so as to ride between the inner surface of the liner and the periphery 2| of the piston.

This packing I2 is preferably made of a resil- 'ient material 23 such as natural or synthetic rubber or such other material as may have the desired properties. In view of the fact, however, that this packing is subjected to such enormous pressures, it may be desirable to provide a reenforcing 24 which may be in the form of fabric which is molded with the rubberat the time'the packing I2 is formed. It has been found that canvas fabric-is most suitable for this purpose and has been illustrated as being'confined to an area adjacent the base where the pressure imparted to the packing is transferred to the flange I 0. The rings are preferably of the same composition throughout with only thereenforcing material therein as distinguished from some prior pistons having composite hard and soft materials. if

The outer end 26 of the packing I2 is conically dished to form a straight annular conical face 21 against'a portion of which the fluid pressure is applied during the working stroke.

By providing a straight line face 21 the of the face 21 in that it is a frusto-conical plate which is preferably of uniform thickness. It should be particularly noted, however. that the taper'of this plate 30 is different from the taper of the face 21 so that normally there will be an opening 3| between the outer edge 32 of the plate 3|) and the end face 21 of the packing. This opening 3| will be observed as-gradually decreasing until it disappears entirely at approximately the point 33,"where the inner face 34 of the retainer plate comes in contact with the end face 21 of the packing member and for the remainer of the distance extending toward the center of the plate 30 it is in close clamping contact with the face 21 of the packing. This clamp, usually holds the packing base 20 firmly against the face It of the flange In so that there can be no leakage along the inside of the packing and no movement of the packing on the A particular advantage of this construction is a flat surface 20 which serve as a base and abut packing l2 can move slightly in that area adja'cent the lip 22 there will be less drag on the liner and consequently less wear: on the packing.

The space 3| provides a limited movement for the outer portion of the packing while the inner portion of the plate 3|! holds the packing clamped securely in' position.

Another advantage of having the space 3| is that in many instances the packing material 23 and particularly the reenforcing material 24 effects a considerable swelling when it comes. in contact with the liquid being pumped. This is particularly true if the pump is permitted to remain idle for some time, or encounters some oil in the liquid being pumped. It being understood that rubber has a great'aflinity for oil and will absorb oil from the mud beingpumped; such absorption, of course, causes swelling of the rubber. The space 3| under these conditions will accommodate a considerable amount of them crease in size of the packing material. If the packing were securely clamped inposition with no opportunity for expansion longitudinally it would, of course, create an excessive pressure of the periphery 2| against the liner wall. When sumcient excessive pressure occurs the material of the packing is burned away by frictional contact with the liner when the pump operates and thepiston is destroyed or less eflicient thereafter.

The plate 3|! may be locked in position by a clamping or locking ring 40. This ring is best seen in Fig. 2 and is of a spring material having the ends 4| and 42 offset so that it may be readily positioned in the groove 44 which is formed adjacent the endof the hub or body 1. In order to insert this ring the end 4| will .be located in the groove 44 and then the ring will be followed around with a tamping tool until the end 42 snaps into position into the groove 44.

' It will be observed that this ring 40 is of special configuration in cross-section having flattened the fact that the space 3| is provided so that on when subjected to suction candraw down slightly so that the face 21 may move out against the retainer plate 30. Naturally when the piston is moving to the right as viewed in Figfll the packing II will be on the suction stroke and it is desirable to have as little friction as possibleof the periphery 2| against the liner. Thus, if the In Fig. 3 the packing material has been arof the packing directly in front of the reenforced sides 45 to engage the sides of the groove 44 and beveled faces at 46 and 41 so that it will form a flat bearing contact with the face 48 of the retainer plate 30. In this manner a maximum strands will have the ends such as 5| exposed on the outer periphery of the packing. Other of the strands such as the strands 52 will be completely imbedded in the resilient material 23 so that such strands will not be exposed to moisture and swell. In order to bring the reni'orcing materlal out to the periphery where it is desired, some of the strands may come to the very periphery of the packing but the majority of them will be entirely sealed against moisture.

It seems obvious that when pressure is applied to the piston during the working stroke that there will be a flowing of the resilient material toward the flange l0 and the reenforcing material is so positioned that it will prevent expansion ranged in'a manner so that it is Ofgreater thickness at the point 55 which approximates about the mid-area of the packing. In this manner v the packing material may be accommodated.

While Fig. 1 shows the allowance for the expansion in the form of a different taper onthe packing from the taper on the retaining plates,

Fig. 4 shows the plate 30 as being provided with.

a plurality of openings Bl which are best seen in Fig. 5. In this Fig. 4 form of the invention the plate 30 is shown as abutting closely against the face 21 of the packing member l2 so that it forms a firm contact therewith and retains the packing against the flange ill at all times, so that it cannot be torn loose from its support on the suction stroke. In event the packin material swells or expands, however, the openings Bl permit this expansion and the packing material will be slightly exuded through these openings so that it will not cause an undue or excessive pressure against the liner wall.

Fig. 6 shows another form of the invention where the plate 30) is also of the same taper as the face, 21 of the packing 12. The packing, however, has been hollowed out at 65 in order to form a cavity 56 which is beneath the Plate 30 and inside of the circumferential edge thereof. Normally the plate will bear against the packing body at the point 61 and'at-the point 68 near,

the outer edge thereof. Thesetwo points, or line contacts, will support the packing member sufllciently to. hold it in place, but in event of swelling the packing material can move into the cavity 66 and in this manner excessive pressure on the cylinder wall is avoided.

Fig. '7 shows another modification wherein the face 21 is a straight conical surface, but the plate 30 has been shown as being concaved at 69 in order to form the cavity 10. This cavity is similar to the cavity 65 in the Fig. 6 form of the invention, but is formed by the curving of the plate rather than v the cutting away of the packing material. In this form of the invention the contact with the packing is had at 61 and at E8, the

same as in Fig. 6.

In Figs. 4, 6,, and 7 the snap ring 40. is utilized to retain the plate in position, the same as is shown in Fig. 1.

Broadly the present invention contemplates the replaced, without removing the core and flange,

It should or the nuts 4, from the piston rod 2. be remembered that one of the greatest difliculties in the operation of the slush pump pistons of this type is maintaining the core and hub in rigid position upon the rod 2 so as to avoid leakage or loosening of the piston with respect to the rod.

Therefore, if the core can he fixed permanently upon the rod in the shop before the rod is.in-

stalled in the pump then it is almost certain that no future difllculty will result. If the outer packing member is to be replaced only one snap ring and plate can be removed, whereas if both packing are to be replaced the rod can be removed from its position, but the core and flange need not be molested.

What is claimed is:

1. A piston including a metal body, an outwardly extending rigid rib on said body a packing member firmly seated on said body and held against flexing by said rib, a concave outer end on said member, a dished retainer plate of an angle diflerent from the concavity of said end and adapted to pass over the end of said body, and means to hold said plate in position.

2. A.piston including a metal body, an outwardly extending rigid rib on said body, a packing member seated on said body and supported against movement by said rib, a concave outer end on said member, a dished retainer plate to passover the end of said body, and means to hold saido plate in position, the taper of said member and plate being difierent to provide an expansion area for said member adjacent the periphery of said plate.

3. In a piston having a rigid packing supporting body, a removable packing ring firmly sup ported thereon, a conically .dished end on said ring, a conically dished retainer plate of a steeper taper than said end and disposed so that said plate abuts said end adjacent the center but is spaced from the end adjacent the periphery.

4. In a piston having a rigid packing supporting body, a removable packing ring seated thereon, a conically dished end on said ring, a conically dished retainer plate of a steeper taper than said end and disposed so that said plate abuts said end adjacent the center but is spaced from the end adjacent the periphery whereby the said packing may move into the space against said plate on the drag stroke of the piston.

5. A piston comprising a rigid body and flange assembly, a packing ring to slip on each end of the body and to abut against said flange to be supported thereby, said ring having a resilient conical retainer plate of a difierent taper thansaid end, a lock ring to hold said plate to said body, the diiferent tapers of said plate and packing ring providing an annular space between the plate. and packing ring so that said packing ring may move into said space when subjected to drag or pressures so that excessive friction on the liner walls will be avoided. V

6. A pump piston including a packing ring, a support therefor, means including a plate to retain said ring in operative position on said support, and additional means to allow for swelling of said ring comprising a recess between the end of said ring and plate .and into which the packing may flow upon swelling thereof, said recess being formed in the packing ring.

'7. A pump piston including a packing ring, a support therefor, means to retain said ring in operative position on said support including a plate and lock ring, and additional means to allow for swelling of said ring comprising a recess between the end of said ring and plateand into plate outwardly from the end of the ring.

8. A pump piston including acircular packing ring flaring outwardly toward its end, which flaring portion is adapted to be confined by the pump cylinder to a circular form thereby causing flexing, tending to elongate the ring, a support therefor upon which said ring is firmly seated, means including a plate to retain said ring in firm position on said support, and additional means comprising a portion of said'plate shaped to allow for flexing of said ring by providing a recess between a portion of the end of said ring and said plate portion and into which the packing may flow upon flexing thereof.

outwardly'extending rigid rib on said body, a

I packing member seated on said body and against said'rib, a conical outerend on said member, a conical retainer plate to pass over the end of said body, and means to hold said plate in position, the inclination of said member and plate being such as to providean expansion area for said member adjacent the periphery of said plate.

9. A piston including a ,rigid metal body, an

DUDLEY C. SHARP.

RANALD M. GARRISON.