US3049082A - Reciprocating pump - Google Patents

Description

Aug. 14, 1962 w. R. BARRY RECIPROCATING PUMP 2 Sheets-Sheet 1 Filed May 26, 1958 V\///// 0/77 F. Barry INVENTOR.

EQQQA abum ATTORNEY Aug. 14, 1962 w. R. BARRY RECIPROCATING PUMP 2 Sheets-Sheet 2 Filed May 26, 1958 W m wmmwmmmwmm gm w f :13: 5 8 wmm m m7\ vvfi 2 m 3* 32 W HZ 3 2 ATTORNEY United States 3,049,082 RECIPRGCATHNQ PUMP William R. Barry, Wichita, Karts, assignor to John W. Mecom, doing business as Cardwell Manufacturing Company, Houston, Tex.

Filed May 26, 1958, Ser. No. 737,610 2 Claims. (Cl. 103-216) This invention comprises novel and useful improvements in a high pressure reciprocating pump, more specifically pertaining to a reciprocating pump especially adapted to produce the'large discharge volumes required for circulating oil well drilling fluids, and the high pressures required for fracturing subterranean oil formations by hydraulic means.

This is a continuation-impart of application Serial No. 539,369, High Pressure Reciprocating Pump, filed Octo- 'ber 10, 1955, Patent 2,842,060 patented July 8, 1958.

My invention is intended to provide improved construc tion features in a reciprocating pump of the type adapted for oil well use, whereby the unit is readily convertible from high volumecomparatively low pressure operation to comparatively low volume-high pressure operations; the pump design is of as simple and economical a character as possible; the servicing of the components of the pump is easily effected; a novel and improved packing assembly is provided for the pump plunger or piston; and an improved lubricating means is provided for the pump plunger or piston.

My invention has specific application in single-acting reciprocating pumps. This general type of fluid pump is well known in the art. Its basic components are a fluid cylinder, including inlet and outlet means, a plunger which reciprocates within said cylinder, and means for the transmission of power to said plunger. In such a pump fluid is pumped on only one side of the plunger, power for reciprocation usually being supplied at the other end of the plunger. It is therefore common terminology, for purposes of description, to refer to the power end and the fluid end of the cylinders of a single acting pump.

It is well known in the art and quite evident that for a pump of this nature to operate satisfactorily, the fluid must be confined to the fluid end of the cylinder, allowing little or no leakage past the plunger. In order to accomplish this end, various packing materials and devices are used which act to effect a fluid seal between the internal cylinder walls and the plunger, thereby confining the fluid within the cylinder.

One problem in the prior art, however, is that the cylinders, plungers and packing are so constructed that removal of the packing can be accomplished only at the power end of the cylinder. To effect such a change, it is normally necessary to work around the plunger which projects from the cylinder and is attached to the power transmission means. This method is quite diflicult and time-consuming.

Likewise, in the prior art pumps the removal or replacement of the plunger is quite diflicult due to the fact that it must be detached from the power transmission means, which operation can be accomplished only in the confined space bounded by the power end of the cylinder.

Moreover, in the prior art devices, a change of plunger size is a laborious operation which can be accomplished only by a major disassembly and overhaul, it being necessary to remove and replace both plunger and packing.

It is therefore an object of this invention to provide a fluid cylinder, 21 fluid plunger and a packing assembly which are designed to facilitate replacing the plunger, the packing or both.

A further object is to provide a fluid cylinder, a fluid plunger and a cylinder liner and packing assembly that 3,049,082 Patented Aug. 14, 1962 are designed to permit the plunger size to be changed quite simply.

In the methods of packing known heretofore, concentric annular rings of packing are disposed one on top of the other, thereby providing a series of individual seals which cooperate to prevent leakage between the cylinder and plunger. In such a packing arrangement in a high pressure pump, it has been noted that the packing which is relatively close to the power end of the pump, sometimes referred to hereinafter as the lower packing, is the first to fail or wear out. This inherent weakness is believed to be the result of increased column loading on the lower packing, and decreased resiliency resulting therefrom. It is therefore a further object of my invention to eliminate or minimize this defect by providing a fluid packing assembly in which the lower packing is so arranged and supported as to provide increased axial load. bearing capacity with respect to the upper packing.

In the drawings:

FIG. 1 is a vertical transverse section of a fluid pump constructed in accordance with one form of my invention;

FIG. 2 is a vertical transverse section through a fluid pump constructed according to a modified form of my invention; and

FIG. 3 is an expanded view of a part of FIG. 2.

In FIG. 1 the cylinder 12 is mounted to crankcase 16 by means of hollow pyramidal base 18 which is secured to and rises from the crankcase 16 and supports the cylinder as by welding or by any other suitable fastening means. It will be observed that the cylinder at its outer or head portion is provided with an integral downwardly extending inlet conduit 64 which is detachably connected to an intake pipe 66.

Also carried by the head portion of the cylinder and extending upwardly therefrom is discharge conduit 68, which is connected to and communicates with a suitable discharge pipe, not shown.

It will be seen that the inlet conduit 64 is provided with non-return upwardly opening inlet valve 76 by means of which the fluid may pass into the working chamber 78 of the head portion of the pump cylinder. Similarly, nonreturn discharge valve 80 is provided in the discharge conduit 68 and closure plug 82 is provided in the upper end of the latter for affording access to the discharge valve. As will be further apparent from FIG. 1 the head end of the cylinder is provided with a removable closure plug 84 whereby access may be had to the pump chamber 78.

The cylinder 12 is provided with a bore 86 in which is received a cylindrical plunger 88. This member is operatively connected by a power transmission assembly to suitable power means such as a crankshaft, not shown. The plunger slides through a guide and packing bushing 90 detachably secured in the upper end of the cylinder bore 86 as by a snap ring 92, and through a packing gland nut 94 threadably engaged in the lower end of the bore.

The plunger 38 is releasably attached to a cross-head 188 by means of an upwardly extending externally threaded boss 114 on the crosshead which mates with the low internally threaded hollow extremity thereof. A projecting lug 116 at the upper end of the plunger provides means whereby it may be grasped by a suitable tool and rotated for disconnection from the crosshead. The abutting faces of plunger 88 and crosshead 108 are closely machined to establish a precise parallel relationship therebetween whereby they may be secured jammed together by suitable torque applied to lug 116 to prevent working loose during operation.

The power transmission assembly for reciprocating the plunger may be best seen in FIG. 1. It will be noted that the crankcase is provided with a cylindrical bore in alignment with cylinder 12. A sleeve or liner 102 is received within the bore 100 and retained therein by a cylindrical ring 104 having fastened bolts 106. The crosshead 108 in the form of a piston is slidably received within the sleeve 102 and is connected by a wrist pin 110 to a connecting rod 112, the latter extending to a suitable conventional crank, not shown.

Further referring to FIG. 1, it will be seen that the cylindrical ring or packing gland 104 is provided with a central opening at its outer end and with a dimetrically enlarged cylindrical bore 122 extendnig outwardly from its inner end. The opening and bore permit passage of piston plunger 88 for sliding movement therethrough during reciprocation of the crosshead 108.

A packing assembly is received within the bore 122. This includes a cylindrical body or sleeve 124 which is removably received within the bore 122, and releasably retained therein by split ring 126, an annular packing O-ring 128 being positioned between the outer end of the sleeve 124 and the shoulder formed by the junction of the bore 122 and opening 120. Secured in the sleeve 124 is a packing or sealing ring 130 which embraces the plunger 88. In this manner, a fluid-tight seal is established between the reciprocating plunger and the cylindrical bore within which the crosshead reciprocates. The lubricant contained in the crankcase for lubricating the crosshead is thus prevented from escaping therefrom.

It will be observed that the crosshead packing assembly may be serviced when necessary by detaching and removing the cylinder 12 and base 18 from the crankcase section and thereafter removing and replacing the packing glands 104 and the packing assembly carried thereby.

Seated in the cylinder bore 86 adjacent the outer and inner ends of the same and respectively abutting the guide sleeve 90 and the packing gland 94 are packing means 136 and 138 which may be of any desired character. These packing means thus surround the plunger 88. Separating the two sets of packing means is a ring-like member 140 which also surrounds and slidably receives the plunger and has a snug sliding fit in the bore 86. This ring-like member is thus disposed intermediate the packing means and constitutes an element through which lubricant is supplied to the pump plunger.

The member 140 is provided with circumferential outer and inner grooves 142 and 144, the former continuously communicating with lubricant circulation passages 146, while the latter continuously opens upon the external surface of the plunger 88. By means of nipples or elbows 148 which communicate with the passages 146 and with supply conduits 150 to a suitable reservoir, not shown, lubricant under pressure may be circulated through the packing assembly directly to the plunger. It will be ob served that the pressure of this lubricant will also serve to further compress the packing assemblies 136 and 138 against their respective end abutments 90 and 94.

Base member 18 has one or more openings therethrough which provide access into the space between the crosshead and the lower exterior of the cylinder 12. Such openings may remain unclosed, or a closure member similar to the cover 270 shown in FIG. 2 and described in a subsequent paragraph may be provided.

In order to change plungers on the form of my invention shown in FIG. 1, it is only necessary to remove the cap 84, seize lug 116 by a suitable tool, manipulate the tool to unscrew the plunger 88 from the threaded boss 114 on the crosshead 108, withdraw the plunger through the opening in the fluid end of the cylinder, insert a new plunger, lock it into position on the crosshead by application of suitable torque on the lug, and replace the cap.

If it is desired to change the packing with the plunger in place, this operation may be accomplished by removing the cap 84, releasing snap ring 92, working the bushing 90 and the packing and lubricating ring upward along the plunger for removal through the fluid end,

inserting new packing in a similar manner and putting snap ring 92 back in place. Adjustment of packing nut 94 is made as required through the previously described openings in base member 18. If it is desired to change the packing while the plunger is absent from the cylinder, a similar procedure is followed.

In order to move large volumes of fluid, the displacement of the reciprocating plunger must be correspondingly large. On the other hand, the plunger displacement must be kept to a relatively small amount in order to develop the high pressures required for the hydraulic fracturing of subterranean formations. Varying conditions may require any of several intermediate levels of volume or pressure, and in order to provide ready means for adapting my pump to such demands, I contemplate ready and quick replacement of the plunger, it being apparent that a small plunger displaces less volume at each stroke than a large plunger.

To change plunger sizes, cap 84 is unscrewed and the plunger 88 is removed as previously described. The packing nut 94 is loosened somewhat and then the snap ring 92 is removed from place. The packing nut 94 is unscrewed and removed from the power end of the cylinder through the openings in base member 18 and replaced by a packing nut of complementary dimensions to the new plunger, but otherwise configured as nut 94. The packing assembly is removed from the head opening and replaced by a packing assembly of a size complementary to the new plunger to be inserted. The snap ring 92 is then replaced and the new packing nut adjusted to support the packing loosely. The new plunger, configured as 88 but of the desired external diameter, is inserted through the fluid end of the cylinder and screwed into place on the crosshead 108. The packing nut is then tightened to the proper degree and the cap 84 is replaced.

FIG. 2 illustrates a somewhat modified form of my invention. The cylinder 200 is integrally cast with a lower base portion 201 which is attached to crankcase 202. Also integrally cast with the cylinder are intake 203 and discharge 204. Suitable intake and discharge valves, not shown, are provided. These valves are similar to those shown in FIG. 1.

The head end of cylinder 200 is formed by removable closure cap 200A. Plunger 205, an elongated cylindrical member with an axial hole drilled partially therethrough, is secured to crosshead extension rod 206 by engagement of internal threads on the inner circumferential surfaces of plunger 205 with the threaded boss 207. Extension rod 206 may be releasably attached to the crosshead, not shown, or it may form an integral part thereof. The choice of arrangement is a matter of convenience, and the important element is the provision of precise parallel abutting faces between the lower end of the plunger and the upper end of the extension rod whereby the two members may be securely locked together without the benefit of a jam nut. This arrangement is similar to that shown and described in connection with the FIG. 1 embodiment, and allows ready disconnection from the fluid end of the cylinder by means of the projecting lug 208 at the opposite end of the plunger.

A bafile 209 is carried about extension rod 206 immediately below the boss 207. This member serves to prevent leakage of lubricant and the fluid in the cylinder from the plunger downward onto the extension rod.

The construction of the FIG. 2 embodiment below the cylinder is as shown and described in connection with FIG. 1 with certain exceptions. The wiper assembly whereby the annular space within crosshead cylinder sleeve 220 is sealed from the cavity 221 between the crankcase and the cylinder is somewhat modified. It comprises wiper housing 225, wiper 226, wiper housing nut 227, snap ring 228, O-ring 229 and wiper housing support roll pin 230. The wiper 226 is an annular ring of any suitable packing material which is supported in place I snugly about the circumference of the extension rod 206 by the assembly just described. The wiper housing nut 227 provides a convenient means to adjust the wiper packing tightness.

The packing assembly, indicated generally as 235 in FIG. 2, is shown in detail in FIG. 3. The packing assembly 235 cooperates as a unit to provide sealing and guiding means for the plunger 205. The inner circumferential portions of the assembly surround the outer surface of the plunger 205 and the outer circumferential portion of the assembly are supported by the interior portions of the walls of the cylinder 200. The assembly 235 comprises an annular cylinder liner and packing housing 240; upper and lower packing means 241 and 242, respectively, which may be any suitable pump packing material; oil ring 243, made as ring 140 previously described, known in the art as a lantern ring; and packing ring 244. An annular oil supply groove 245 and communicating passage 245A are provided about housing 240. An additional annular groove 246 is provided about the upper portion of housing 240 and communicates with the passage 247 through the cylinder wall. The purpose of such arrangement is described in a subsequent paragraph.

It will be noted that housing 240 is provided with inwardly and outwardly extending flanges or shoulders 250 and 251 on its upper extremity, the former serving to support the packing against movement in a direction toward the fluid working cavity and the latter serving to retain the housing from movement downward through the cylinder toward the power end of the pump. The flange 251 seats on flange receiving surface 252 which is formed in the cylinder wall structure. The flexible sealing ring 253 renders this joint fluid-tight. The groove 2'46 and passage 247 provide visible evidence of leakage past sealing ring 253.

The packing housing 240 carries threads 255 intermediate its ends on its exterior surface. These threads are adapted to engage packing housing nut 256, a cylindrical member which is held loosely in place within the countersunk lower portion of the cylinder by the packing housing nut retaining screw 257. The terminal end of the screw 257 is received within a slot 258 in the external Wall of the nut 256 and holds the nut within the cylinder. As the packing housing is engaged therewith by means of the threads 255, the nut is pulled upward to bear against the internal shoulder of the cylinder and lock the housing into position. The walls of the cylinder might be threaded directly, thereby eliminating the need for nut 256; however, the use of a replaceable part allows ready repair in the case of damage to the threads rather than requiring a new cylinder or an extensive rework job on the old one.

The packing ring 2144 is externally threaded for connection with the internal threads 259 in the lower portion of the packing housing 240. The upper end of ring 244 abuts the lower face of lantern ring 243 and the lower packing means 242 is carried within a recess in the internal wall of ring 244. The upper packing means 241 may be compressed by adjusting the position of ring 244, for which purpose the lower shoulder 246 of ring 244 is provided with wrench flats.

Conduit 260 through the wall of the cylinder 200 is located to coincide with the oil groove 245 when the packing housing is in place. Two O-ring seals indicated by reference numerals 261 and 262, respectively, are carried about the packing housing 240 above and below the groove 245. These elements prevent leakage of the lubricant which is supplied to the lantern ring 243' through conduit 260 and groove 245.

It will be evident from an inspection of FIGS. 2 and 3 that a change of plungers or packing is quite simple. To change the packing it is only necessary to unscrew and remove the closure cap 200A, and unscrew and pull the packing housing 240. The shoulder 246 is approximately the same diameter as the housing 240 so that it may be lifted through the nut 256. Repacking of the housing is performed outside of the pump and the entire assembly as a unit is returned through the open cylinder head to its position within the cylinder. Compression of the upper packing 241 may be accomplished by tightening the ring 244 either before the packing housing is placed in the cylinder, or after it is in place, the latter operation being performed through the opening provided by removal of cover 270 from the base portion 201.

The plunger may be replaced by removing the cap 200A and manipulating lug 208 with a suitable tool to unscrew the plunger from extension rod 206. The plunger is then lifted from the cylinder and a new one is inserted by the reverse of the operation just described.

If it is desired to replace a plunger by one of larger or smaller diameter, the packing assembly and plunger are removed and replaced by a new plunger of the desired diameter and a packin assembly of complementary dimensions thereto. The complementary packing assembly comprises a packing housing and packing ring with the same external diameters but with thinner or thicker walls, depending on whether a larger diameter or smaller diameter plunger is to be installed. It is apparent that the packing and lantern ring must be of proper dimensions to seal about the new plunger.

It has been observed that the portion of the packing furthest removed from the fluid working chamber in the cylinder, tends to fail first in a high pressure single acting pump. The problem of providing a seal which will render satisfactory service over an extended life has led to the development of my present novel packing assembly which is the result of extensive tests. The discovery that the sizeable increase in column loading on the packing elements toward the bottom thereof tends to shorten its life, and the development of novel structure which reacts such loads without damage to the seal is an important feature of my invention.

In solving the above described problem, I have developed a lower packing unit which is designed to carry a larger compressive load with respect to forces parallel to the axis of the cylinder than the upper packing unit. In my presently preferred embodiment, the internal packing ring 244 separately houses the lower packing, and in effect, causes the lower packing unit to act as a reinforced structural column. Although ring 244 as shown is a single member, it is apparent that its several functions could be performed by separate abutting members, as, for exam ple, a separate sleeve surrounding and supporting the packing 242 and an adjustable nut adjacent thereto for movement along the threads 259. Any such modifications of design are within the scope of my invention.

As an additional feature, I have found that the life of the upper packing 241 is substantially increased by the insertion of a bearing ring 263 immediately above the lantern ring 243. The tapered surface on the top of the bearing ring more effectively supports the lower portion of the upper packing 241. The bearing ring could form a part of the lantern ring, or both of these members could be integral with the ring 244.

It is apparent that any of several well known structural devices could be employed to reduce the unit column loading on the lower seal, and such equivalent arrangements are within the scope of my present invention.

It is also apparent that while I have chosen to illustrate and describe but two embodiments of my invention, many modifications can be made by one skilled in the art without departing from the spirit thereof. I therefore contemplate to protect by the following claims all forms of my invention.

I claim:

1. In a single acting pump having a cylinder with a power end and a fluid end and a reciprocating plunger within said cylinder. the combination of an opening at said fluid end of said cylinder, a removable plug sealing said opening, a removable packing housing carried within said cylinder, said packing housing being of lesser external dimension than said opening at said fluid end of said cylinder for passage therethrough when said plug is removed, packing means within said packing housing around said plunger to maintain a sealed relationship therebetween, a countersunk bore extending into said cylinder at the power end thereof, a packing housing retaining not within said bore releasably engaging the external periphery of said packing housing, and releasable locking means attached to said cylinder and contacting said retaining nut to secure said nut in said bore.

2. In a single acting pump having a cylinder with a power end and a fluid end and a reciprocating plunger within said cylinder, the combination of an opening at said fluid end of said cylinder, a removable plug sealing said opening, a removable packing housing carried within said cylinder, an adjustable packing nut attached to said packing housing within the lower portion thereof, said packing housing and packing nut being of lesser external dimension than said opening at said fluid end of said cylinder for passage therethrough when said plug is removed, packing means within said housing around said plunger to maintain a sealed relationship therebetween, secondary packing means within said packing nut around said plunger, a countersunk bore extending into such cylinder at said power end thereof, a packing housing retaining nut within said bore releasably engaging the external periphery of said packing housing, and releasable locking means attached to said cylinder and contacting said retaining nut to secure said nut in said bore.

References Cited in the file of this patent UNITED STATES PATENTS 545,399 Wilson Aug. 27, 1895 978,611 McLain Dec. 13, 1910 1,291,983 Maisch Ian. 21, 1919 1,958,221 Wilcox May 8, 1934 2,250,164 Minder July 22, 1941 2,426,613 Jackson Sept. 2, 1947 2,509,162 Moses et a1 May 23, 1950 2,595,592 Magnuson May 6, 1952 2,673,103 Tremolada Mar. 23, 1954 2,766,701 Giraudeau Oct. 16, 1956 2,828,696 Wright Apr. 1, 1958 FOREIGN PATENTS 122,585 Great Britain Nov. 7, 1946

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