US2808302A - Piston sealing means - Google Patents

Description

OC- 1 1957 H. E. BowERMAN PIsToN SEALING MEANS' Filed Dec?. 9, 1953 Iliff IN VEN TOR. am /5 t aowEf/f/AA/ ATTK ilnited States Patent falce PISTON SEALING MEANS Hulie E. Bowerman, Arlington, Tex.

Application December 9, 1953, Serial No. 397,211 7 Claims. (Cl. 309-23) This invention relates to pump pistons and, more particularly, to that type of piston which is employed in the pumping of circulating media used in the rotary drilling process.

The invention relates to improvements in pump pistons such as disclosed in my co-pending application for United States Letters Patent, Serial Number 396,584, filed December 7, 1953, and in my U. S. Patent No. 2,687,335.

The pump piston art is composed of two general types of pistons, which are either of the replaceable sealing member type or those in which the sealing members are non-replaceable and the piston core or body is discarded when the sealing members are no longer usable, each type having its peculiar advantages and disadvantages. Pump pistons embodying my novel features, as hereinafter s et forth, will have departed from the disadvantages of both mentioned types of pistons and will yet retain all of the advantages inherent to both types, said main advantages of the replaceable sealing member type being economy, installation of new sealing members without removal of the piston body from the piston rod, and the minimum time required to replace the pump in operation. The main disadvantage in this type piston, which is not present in the non-replaceable type, stems from diiculties arising in design and/ or manufacture of the component parts which allow the pumped iluids to enter and pass through the zone between the piston body and the sealing members, resulting in erosion of one or both parts and ultimate destruction of the usefulness of the assembly due to the cutting action of the fluids under pressure. j

The manner in which these novel features are incorporated into a new workable piston form will be readily understood by those skilled in the art from the following description together with the accompanying drawings wherein:

Fig. 1 is a half sectioned elevation of a preferred form of my piston partly assembled.

Fig. Il is a half sectioned elevation of a preferred form of my piston sealing member.

In the several figures like references indicate similar parts wherein: 1 is a piston body provided with suitable aperture 2 for receiving a conventional piston rod, not shown, and having a medially disposed radial web 3, and a groove (i for receiving snap ring 5, and a portion 6 which is a frustrum of a cone concentric with the main axis of the body, and its base portion terminating adjacent web 3, and its upper portion terminating at shoulder 13, said outer construction of body 1 being symmetrical about the plane of the transverse axis of web 3. 7 is a sealing member of rubber or some other resilient material bonded to and supported by a metal sleeve 8 and retainer plate 9. A rubber-like sealing member 10, having arcuate ridge 11, is carried by sleeve 8 on its inner diameter and, as illustrated in the several views, may be of softer composition than sealing member 7. Sealing members 7 and 10 extend upwardly along sleeve 8; sealing member 7 terminating in sealing lip 14 which effects sealing engagement with the pump liner not shown. Annular recess 15 is formed between sealing lip 14 and outer edge of plate 9. Bonding of metal plate 9 into sealing member 7 obviates the necessity of manufacturing metal plate 9 to an expensive close tolerance as would be necessary if said plate was not molded into the part but added as an individual unit to the assembly. When said plate is used as an insert to the mold during the molding operation the upper surface of said plate is retained against the respective mold surface, thereby limiting the effect of a thickness variation in plate 9 to a greater or lesser intrusion of plate 9 into the resilient material of the assembly. A further sealing extension 12 of sealing member 10 lies along, and may be bonded to, the underside of retainer plate 9. Y

' The assembly and operation of my improved piston is as follows: the rubber-like material of sealing member assembly as shown in Fig. II is molded and bonded to its metal components by conventional techniques from lInaterials of selected physical characteristics as determined by the operating conditions under which the piston is designed to perform. Sealing member portion 10, which lies adjacent portion 6 of the piston body after assembly of the parts, is molded to an interference diameter with respect to portion 6,resulting in a wedged, duid-tight seal between the parts when assembled. The upper half of Fig. I illustrates the relative position of the parts when the piston assembly is completed and shows arcuate ridge 11 having beenk distorted 'beyond visual appearance. The lower half of Fig. I shows a piston seal member partly processed onto the piston body, and illustrating that arcu-v ate ridge 11 is-in intereference with tapered portion'6 before assembly is complete, which interference increases with travel downward of the sealing member along tapered portion 6 until assemblyl is complete. Since the angle between a'line in' the planeofthe face of' tapered por'- tion 6 and the main axis of the piston body is relatively small great forces of compressionV are generated upon arcuate ridge 11 and sealing portion 10 even though only nominal thrust pressures are used to force the assembly of the sealing member onto the piston body. This seal is aided by the presence of arcuate `ridge 11, providing an excess of rubber which, upon compression of the assembly into operating position, will extrude or flow to any portion ofthe mating tit in which a cavity might exist due to manufacturing imperfections or deformation suffered by the piston body during previous service or in mounting or dismounting the piston body with the piston rod. Such deformations occur as the result of common field practice of performing these operations with the aid of repeated blows with heavy instuments. .Further novel sealing action is effected by extension 12 of sealing member 10 which, when the assembly is 'compressed into operating position and snap ring 5 forcibly inserted into groove 4, is impinged between shoulder 13 and retainer plate 9. The entire iiuid-tight seal which now exists between the replaceable sealing member 7 and body 1 is aided by uid pressure when the piston assembly is op,- erating in the pump. Fluid pressure generated by for-Y ward movement .of the piston in the pump exerts pressure normal to the sloping sides of annular groove 15. Being formed of resilient material these sides will tend towards displacement away from said pressure. The outer sloping face of groove 15 comprises a portion of the resilient material of sealing member 7'which lies between annular groove 15 and sealing lip 1.4, which portion has as one of its confines the pump liner. Sealing 'lip 14 is aided in its function in that as higher pressures are generated the pressure-aided urge of lip 14 against Vthe pump liner is proportionately greater.

annular groove 15; that face being integral with the resilient material which comprises the zone between the inner face of retainer plate 9 and the upper extremity of the longitudinal portion of metal sleeve 8. This vportion tends to displacement away from the pressurized uid and towards its confines, one of which is tapered portion 6 of body 1, resulting in a pressure aided seal between sealing memberl 10 and tapered portion 6 of body 1. The resilient material bonded to plate 9 will go under tension as forces of pressure in the cylinder against sealing member 7 tend to distort the resilient ,material below lip 14 about groove 15 away from the plate and will aid in retracting this distorted portion of sealing member 7 away from the wall of the pumpliner on the back stroke as the pressure within the cylinder is relieved against sealing member 7. 5 Y

It is understood that it is the intention to cover all changes and modifications of the examples of the invention herein chosen for the do'not constitute departure from the spirit and scope `of the invention.

What I claim is: p 1. A pistoncomprising a cylindrical metal hub having a medially disposed radial web and having a section which is a frustrum of a cone, a piston seal member formed on its internal surface of resilient material to mate with said section of the metal hub and having an internal radial projection beyond said mating surface to provide an excess 'of resilient material which, upon assembly of the related parts, results in a compression of the resilient material against the conical section of the hub.

2. As a new 'article of manufacture a piston seal member comprising a metal sleeve with a base liange, an annular sealing member of resilient material bonded to the flange and to the outside of the sleeve, and a sealing ring of resilient material bonded to the inside side Vof the sleeve, said resilient materials extending beyond and around the end of the sleeve opposite the angeand -uniting to form a radially inwardly projecting sealingl extension, and a circular metal plate bonded to said extension on the side thereof facing' away from the flange and said plate overlying said extension. t

3. In combination a piston comprising a meal hub having a seal supporting section having an outwardly facing -web at one end and having at its other end an annular reduction in diameter forming ashoulder perpendicular to the longitudinal axis of said hub, a piston seal member adapted to be received on the hub and to abut said web, and said seal having 'bonded into its other end a purpose of illustration whichv Y 4 circular metal retaining plate faced on its inner surface with resilient material, said resilient material becoming compressed between said hub shoulder and said plate when the correlating parts are processed into assembly.

4. In a metal-reinforced fluid-pump piston seal for use on a piston hub having an annular frusto-conical seal-receiving portion, saidrseal comprising a metal sleeve with an annular resilient sealing member bonded to the outside of the sleeve, means for sealing the engagement between the truste-conical portion of the hub and the seal against passage of Huid therebetween comprising, an annular coating of resilient material bonded to the inside Vof the sleeve and having a frusto-conical bore therethrough, and at least one annular inwardly projecting ridge of said resilient material within the bore, the ridge material being displaced with the material of said-coating so that when the seal is assembled to the hub the entire inner surface of the coating material conforms with the outer surface 'of said hub.

5. In a device as set forth in claim 4, said ridge material being of arcuate cross-section and integral with said coating.

6. In a device as set forth in claim 4, the inner surface of the coating except for said ridge material being complementary to the shape of the hub.

7. In a device as set forth in claim 4, said hub having at its smaller end an annular reduction in diameter forming an annular shoulder, and the bore through said coating except for said ridge material being complementary in shape to said truste-conical portion, and said resilient material having a radially inwardly projecting annular sealing extension at the smaller end of said bore adapted to overlie said shoulder; and means to compress said extension against said shoulder when the seal is assembled to the hub.

References Cited in the tile of this patent UNITED STATES PATENTS

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