US2841092A

US2841092A - High-pressure pump

Info

Publication number: US2841092A
Authority: US
Inventors: Irvin R Whiteman; John T Barron
Original assignee: Milton Roy LLC
Current assignee: Milton Roy LLC
Priority date: 1955-08-09
Filing date: 1955-08-09
Publication date: 1958-07-01
Anticipated expiration: 1975-07-01

Description

July 1, 1958 l. R WHITEMAN ETAL HIGH-PRESSURE PUMP Filed Aug. 9, 1955 .one end of the cylinder.

United States Patent HIGH-PRESSURE PUMP Irvin R. Whiteman, Los Angeles, Calif., and John T. Barron, Willow Grove, Pa., assignors to Milton Roy Company, Philadelphia, Pa., a corporation of Pennsylvania Application August 9, 1955, Serial No. 527,319

7 Claims. (Cl. 103-153) This inventilon relates to high-pressure controlled volume pumps and has for an object the provision of a novel liquid end assembly for said pumps suited for use at pressures as high as 50,000 pounds per square inch.

In general, controlled volume pumps of this type include a plunger adapted to reciprocate within a displacement chamber or cylinder of a liquidend assembly. The displacement chamber permits a controlled volume of liquid to be delivered for each plunger stroke, the delivered quantity being determined by the diameter of the plunger and the length of the plunger stroke. While various types of liquid end assemblies have been utilized in the past on controlled volume pumps having operating pressures in the range of up to 30,000 p. s. i., they have, however, left much to be desired in the higher ranges extending up to pressures as high as 50,000 p. s. i. and above, particularly from a standpoint of safety, leakproof operation and long life. These requirements have now been met by the present invention.

In accordance with the present invention there is provided a liquid end assembly including a body member having a passage extending therethrough forming a cylinder for receiving a pump plunger. A suction port and a discharge port extend through the wall of the body member intermediate the ends thereof and communicating with the cylinder. One end of the body member has a portion of reduced diameter and an external shoulder adjacent thereto, the portion being adapted to extend through an opening in the frame or housing of the high-pressure pump. The end of the portion opposite the shoulder is externally threaded and adapted to receive a nut to cooperate with the shoulder in holding the wall of the pump housing securely therebetween. A packing assembly is disposed within the cylinder and adapted to encircle the pump plunger to form a liquid-tight seal at A threaded gland member is disposed at one end of the cylinder and adjacent the packing assembly to retain the packing assembly within the cylinder without interfering with the operation of the pump plunger. A tubular spacer member is disposed within the cylinder adjacent the opposite end of the packing assembly and adapted to encircle the pump plunger. A coil spring is disposed within the cylinder adjacent the suction and discharge ports and engaging the opposite end-of the spacer memberrfrom the packing assembly. A self-centering sealing means is disposed in the opposite end ofthe' body member for holding the springunder V compression against the spacer member and forming a liquid-tight seal at the opposite end of the body member from the packing assembly. As further protection in v1ew of the high pressures to which the liquid end is subjected,

j Within the liquid end.

For more detailed understanding of the invention and 2,841,092 Patented July 1, 1958 for further objects and advantages thereof, reference is to be had to the following description taken in conjunction with the accompanying drawing in which there has been illustratedpartly in section a typical embodiment of the invention.

Referring to the drawings, there has been illustrated one form of a liquid end assembly 10 for a controlled volume pump constructed in accordance with the present invention. This invention is particularly applicable to controlled volume pumps of the reciprocating plunger type which include a reciprocating plunger driven by a suitable drive mechanism preferably provided with stroke adjusting means as well as means for varying the speed of the plunger. As the volume delivered by a controlled volume pump is a function of the plunger stroke length and the stroking speed, the volume delivered may be adjusted either automatically or manually by varying the stroke length or plunger speed. Various forms of plunger operating mechanisms may be utilized with the liquid end assembly of the present invention, an example of which is the stroke adjustment drive fully described and claimed in Saalfrank United States Letters Patent No. 2,640,425. As the stroke adjustment drive forms no part of the present invention, no detailed description of it will be given in the present application.

Referring to the drawing, the liquid end assembly 10 is adapted to be secured to the end wall of a'pump frame or housing 11 such, for example, as the pump housing illustrated in the aforesaid Saalfrank Patent No. 2,640,- 425. The liquid end assembly 10 includes a body member 12 having a passage 13 extending axially therethrough forming a chamber or cylinder for receiving a pump plunger 14 which may be similar to the plunger shown in the aforesaid Patent No. 2,640,425. As the liquid end assembly must Withstand high pressures in the order of 50,000 p. s. i., the body member 12 including the pump chamber preferably is a forged cylinder with the bore 13 which contains the plunger 14 being machined straight through. The walls of the body member surrounding the cylinder 13 are of substantial thickness to Withstand the high pressure. A suction port 15 extends through the Wall of body member 12 and "communicates with the cylinder 13. A discharge port 16 also extends through the Wall of the body member 12 and communicates with cylinder 13. The suction port 15 and the discharge port 16 preferably are disposed in alignment with each other and they may be machined in a straight line, thus providing a minimum number of sections that need be analyzed to determine the stresses that the body member 12 must withstand. The body member 12 is of forged construction in order to provide as dense material as possible to withstand the stresses resulting from the high operating pressures. Fatigue stresses must be carefully considered as these pumps may be operated at pumping speeds as high as strokes or more per minute, and at each stroke the pressure will change from a minimum atmospheric pressure to the maximum discharge pressure. This change in liquid pres sure inside the pump chamber results in cyclic stresses up to the maximum which is a more severe loading than a constant pressure loading or a fluctuating pressure between narrow limits. For pressures up to 25,000 p. s. i., #316 stainless steel has proved satisfactory. For pressures above 25,000 p. s. i., a high grade alloy steel such as SAE 4340 has been successfully employed after heat treating to provide the physical requirements necessary for pumps working against such high pressures.

To firmly secure the body member 12 to the end of the pump housing 11, one end of the body member is provided with a reduced diameter 12a and an adjacent external shoulder 12b. The reduced portion 12a is adapted to extend through an opening in the housing 11 with 3. the shoulder 12b in engagement with the end wall of the housing. A threaded section 18 is provided at the end of the reduced portion 12a and is adapted to receive a threaded nut member 19 for securely holding the .end wall of the housing 11 between-the shoulder 12b and the nut .member 19. In order to prevent any rotation of body member 12 with respect to housing 11, there may be provided a key member 20 extending from the wall of housing 11 into the body member 12.

The pump chamber 13 is provided with a high-pressure packing assembly 25 of any suitable type. The packing assembly preferably comprises a plurality of ring members, some of which are formed from a relatively soft metal such as Babbitt or silver. Chevron type packing may also be used. The novel features of that packing assembly per se form no part of the present invention. As it is preferable to use metal for the sealing medium in the packing, it is also preferable to use an abrasion-resistant plunger to withstand the wiping action of the packing on the plunger. In addition, the plunger must be formed from a material which is rigid enough to overcome column effects. If these requirements were not met, the plunger would tend to bend and the packing would erode the plunger, resulting in pump leakage. Plungers formed from tungsten carbide have proved very successful even at pressures as high or higher than 50,000 p. s. i., and ceramic plungers have proved reasonably satisfactory.

To close the inner end of chamber 13 in body member 12, there is provided a gland cap 26 having an axial opening through which extends the plunger 14. At-the opposite end of the packing assembly-25 there is provided a tubular spacer member 27 adapted to be held against'the adjacent end of packing assembly 25 by means of a coil spring 28. The coil spring 28 isformed by arplurality of turns spaced a subsatntial distance apart in order to permit the fluid to flow freely in through the suction port 15 and out through the discharge port 16. The outer end of the chamber 13 is provided with aselfcentering sealing member 29 to prevent escape of fluid from the end of body member 12. The self-centering sealing member 29 is provided with a conical surface 29a for cooperating'with a corresponding conical surface at the end of chamber 13. These conical or tapered surfaces form interference angle fits with each other, thus providing a liquid-tight seal even under such high pressure operating conditions as 50,000 p. s. i. The sealing member 29 is forced into sealing engagement with body member 12 by means of a threaded plug 30 threadedly secured to the body member 12. As an additional precaution against damage from excessive pressure should there be stoppage in the valves leading from the ports or other parts of the system which might cause the end sealing plug 30 to blow off, there is provided a protective cover 31 threadedly engaging the end of body member 12 and disposed over plug member 30 to dissipate the energy of plug 30 before it ruptures the protective cap 31. The protective cover 31 is formed of a material having a high degree of strength such, for example, as bronze or steel.

Each of the suction and discharge ports 15 and 16 is provided with valve means shown in the drawing as of the ball-check type. The discharge port 16 has been shown in the drawing as diverging outwardly from the cylinder 13. The lower ball seat 40 at the discharge side of the pump is provided with sloping sides corresponding tothe-slope of the walls of the openingwhich it engages in body member 12. The ball seat 40 is provided with a central passageway which is adapted to be opened and closed. by a ball 41. Both the ball 41 and its seat 40 are constructed from a hard material such as tungsten carbide to prevent rapid erosion of these parts. As the pump accuracy can be adversely affected by insufiicient 'or excessive ball rise, the balls are preferably provided with a suitable guide or cage suchiasguide 42 tolimit 4 the ball rise. The upper end of ball guide 42 is engaged by the lower end of an upper ball seat 43 also having a passage extending therethrough and adapted to be opened and closed by a ball member 44. The ball seat 43 and the ball 44 also preferably are formed of the same material as ball 41 and seat 40. The rise of ball 44 is limited by a ball guide 45, and the complete ball valve assembly on the discharge side of the pump is held in position by means of a sealing member 46 which in turn is held against the end of the ball seat 43 by means of .a threaded member 49. The member 49 is provided with an internal shoulder adapted to cooperate with an external shoulder on member 46 and when member 49 is threaded into the wall of body member 12, a pressure will be exerted lengthwise of the discharge valve assembly. Due to the self-centering interference angle fits between

mating members

46 and 43 and 43 and 12, there is formed a fluid-tight seal between these members preventing the escape of liquid between these members other than through the discharge passage. As may be seen in the drawing, the screw threads on member 49 which cooperate with the internal threads on body member 12 perform no scaling function, but are used only to effect the physical loading on sealing

pieces

46 and 43. The upper end of member 49 is internally threaded to receive a high-pressure fitting connecting the discharge line to the liquid end assembly.

The valve assembly on the suction side of the pump is generally similar to the discharge valve assembly previously described. The discharge port 15 is provided with an upper ball valve 50 having a ball seat 51 disposed at the upper end of sealing member 52. The upper end of member 52 is tapered to cooperate with the tapered opening in body member 12, and a central passage extends through member 52 communicating with a lower ball valve including a ball 54 and a seat member 55, the latter being slideably carried by a bushing member 56. The member 56 is provided with an internal shoulder which engages an external shoulder on member 55, and when member 56 is threaded into body member 12, a sealing pressure is applied lengthwise of the suction valve assembly, thus forming a fluid-tight seal between

mating pieces

55 and 52 and 52 and 12 in a manner similar to that described above in connection with the discharge valve assembly. Both the

guides

57 and 58 are provided to limit the rise of

corresponding balls

50 and 54. The lower end'of member 55 is provided with an internally threaded opening to receive the suction line.

With controlled volume pumps having a liquid end const'ructed in accordance with the present invention, it has been possible to provide satisfactory pumping operations at pressures as high as 50,000 pounds per square inch with stroking speeds as high as strokes per minute, and at the same time to have safe, leak-proof operation with relatively long life of the equipment. This has been accomplished while maintaininghigh metering-accuracy and high volumetric efiiciency, thus providing a precision flow control instrument for use at high pressures in the order of 50,000 pounds per square inch which heretofore has only been obtained at lower pressures.

While there has been described a preferred embodiment of the invention, it will be understood that further modifications may be made without departing from the spirit and scope of the invention as set-forth in the appended claims.

What is claimed is:

1. In ahigh-pressure pump, a liquid end assembly comprising a body member having a passage extending therethrough forming a chamber for receiving a pump plunger, a suction port extending through the wall of said body member and communicating with said chamber, a discharge port extending through the wall of said body member .and communicating with said chamber, valve means in each of said ports, said suction and dis- .chargeports being in axialalignment witheach-other and in a plane substantially perpendicular to the axis of said chamber, one end of said body member having a portion of reduced diameter and an external shoulder adjacent thereto, said portion being adapted to extend through an opening in the frame of the high-pressure pump, means for forcing said shoulder against the frame, a packing assembly disposed within said chamber and adapted to encircle the pump plunger to form a liquidtight seal at one end of said chamber, and self-centering sealing means disposed at the opposite end of said chamber and beyond said suction and discharge ports forming a liquid-tight seal at the opposite end of said chamber, said self-centering sealing means including a member having a tapered surface for cooperating with a corresponding tapered surface on said body member at the same end of said chamber.

2. In a high-pressure pump, a liquid end assembly comprising a body member having a passage extending therethrough forming a chamber for receiving a pump plunger, a suction port and a discharge port extending through the wall of said body member intermediate the ends thereof and communicating with said chamber, one end of said body member having a portion of reduced diameter to provide an external shoulder, said portion being adapted to extend through an opening in the frame of the high-pressure pump, means cooperating with said portion to force said shoulder against the wall of the pump frame, a packing assembly disposed within said chamber and adapted to encircle the pump plunger to form a liquid-tight seal at one end of said chamber, gland means disposed at one end of said chamber and adjacent said packing assembly to hold said packing assembly within said chamber, a tubular spacer member disposed within said chamber adjacent the opposite end of said packing assembly and adapted to encircle the pump plunger, spring means disposed within said chamber adjacent said suction and discharge ports and engaging the opposite end of said spacer member from said packing assembly, and self-centering sealing means disposed in the opposite end of said body member holding said spring means under compression against said spacer member and forming a liquid-tight seal at said opposite end of said body member from said packing assembly.

3. In a high-pressure pump, a liquid end assembly comprising a body member having a passage extending therethrough forming a cylinder for receiving a pump plunger, the walls of said body surrounding said passage being of substantial thickness to withstand high pressure, a suction port extending through the wall of said body member and communicating with said cylinder, a discharge port extending through the wall of said body member and communicating with said cylinder, said suction and discharge ports being in alignment with each other, inner valve means disposed in each of said discharge and suction ports, self-centering sealing members disposed in each of said suction and discharge ports exteriorly of said inner valve means, said self-centering sealing members each having a passage extending axially therethrough, exterior valve means disposed in the passages of said self-centering sealing members, additional self-centering sealing members each having a passage extending axially therethrough and cooperating with said first-named self centering sealing members to form a flow passage extending through said self-centering sealing members, and means for applying pressure to the ends of said self-centering sealing members to form liquid-tight seals along the sides of said flow passage respectively between the walls of said suction and discharge ports and said cooperating self-centering sealing members.

4. Apparatus according to claim 3 wherein said valve means includes ball checks and corresponding seats, and guide means for limiting the rise of said balls above said seats during pumping operations to assure pumping accuracy.

5. In a high-pressure pump, a liquid end assembly comprising a body member having a passage extending therethrough forming a chamber for receiving a pump plunger, a suction'port and a discharge port extending through the wall of said body member intermediate the ends thereof and communicating with said chamber, one end of said body member having a portion of reduced diameter to provide an external shoulder, said portion being adapted to extend through an opening in the frame of the high-pressure pump, a threaded section at the end of said portion opposite said shoulder, a threaded member on said threaded section and adapted to cooperate with said shoulder to grip the wall of the pump frame therebetween, a packing assembly disposed within said chamber and adapted to encircle the pump plunger to form a liquid-tight seal at one end of said chamber, a tubular spacer member disposed within said chamber adjacent said packing assembly and adapted to encircle the pump plunger, pressure-applying means disposed within said chamber adjacent said suction and discharge ports and engaging the opposite end of said spacer member from said packing assembly, and self-centering sealing means disposed in the opposite end of said body member holding said pressure-applying means against said spacer member and forming a liquid-tight seal at said opposite end of said body member from said packing assembly.

6. In a high-pressure pump, a liquid end assembly comprising a body member having a passage extending therethrough forming a chamber for receiving a pump plunger, the walls of said body surrounding said passage being of substantial thickness to withstand high pressure, a suction port extending through the wall of said body member and communicating with said chamber, a discharge port extending through the wall of said body member and communicating with said chamber, said suction and discharge ports being in axial alignment with each other and in a plane substantially perpendicular to the axis of said chamber, one end of said body member having a portion of reduced diameter and an external shoulder adjacent thereto, said portion being adapted to extend through an opening in the frame of the high-pressure pump, means cooperating with said portion to force said shoulder against the pump frame, a packing assembly disposed Within said chamber and adapted to encircle the pump plunger to form a liquid-tight seal at one end of said chamber, self-centering sealing means disposed at the opposite end of said chamber and beyond said suction and discharge ports, said self-centering sealing means ineluding a member having a tapered surface for cooperating with a corresponding tapered surface on said body member at the same end of said chamber, plug means for holding the tapered surface of said self-centering sealing means in liquid-tight engagement with the tapered surface of said body member, and a protective cap secured to said body member and over said plug means.

7. In a high-pressure pump, a liquid end assembly comprising a body member having a passage extending therethrough forming a cylinder for receiving a pump plunger, the walls of said body surrounding said cylinder being of substantial thickness to withstand high pressure, a suction port extending through the wall of said body member and communicating with said cylinder, a discharge port extending through thewall of said body member and communicating with said cylinder, said suction and discharge ports being in alignment with each other and in a plane substantially perpendicular to the axis of said cylinder, one end of said body member having a portion of reduced diameter and an external shoulder adjacent thereto, said portion being adapted to extend through an opening in the frame of the high-pressure pump, a threaded section at the end of said portion opposite said shoulder, a threaded member on said threaded section and adapted to force said shoulder of said body member against the Wall of the pump frame, locking means for preventing rotation of said body member with respect to 7 :pump frame, a packing .assembly disposed within (said :cylinder :and adapted to encircle :the' pump plunger etoiformsaliquidstight seal at 'one end :of said cylinder, 21 -'slf-.centering sealing :rnember disposed at the opposite :end 'of ssaid cylinder and beyond said suction and dis- :charge ports, said self-centering sealingrnember having ra :conicl surfacev'for cooperating with a corresponding :conical surface on said Fbodyat the same end of said :cylinder, -a:plug;member,f0r holding the conical surface 'of-said selfaeenteringrsealing member in liquid-tight en- :gagement withthe conical surface of said body member,

,and a protective cap secured to said-body member and over said plug member.

References Cited in the-file of this patent UNITED STATES PATENTS Moore Mar. 17, 1903 Yohpe Oct. 20, 1953 Saalfrank Feb. 7, 1956