US20100008804A1

US20100008804A1 - Pump having improved and adjustable packing

Info

Publication number: US20100008804A1
Application number: US12/386,414
Authority: US
Inventors: Miroslav Liska
Original assignee: Graco Inc
Current assignee: Graco Minnesota Inc; Graco Inc
Priority date: 2008-04-18
Filing date: 2009-04-17
Publication date: 2010-01-14

Abstract

A reciprocating type pump and method with an improved and customizable approach to varying axial pressure is provided. In one embodiment, a pump may be provided with a pump body, a piston reciprocally moveable within a bore of the pump body in response to a piston drive, and axially spaced apart packing means radially expansible in response to axial pressure exerted on the packing means. A packing nut is also provided, which is disposed at the end of the pump opposite the piston drive for adjustably exerting axial pressure on the packings. Springs may also be provided between the axially spaced apart packing means, which may be used for preloading the packing means and compensating for packing wear, swelling and/or dimensional instabilities.

Description

This application claims the benefit of provisional application Ser. No. 61/124,739 to Miroslav Liska, which was filed on 18 Apr. 2008.

BACKGROUND OF THE INVENTION

1. Field of the Invention
This invention relates to an improvement in pumps and more particularly to those of the reciprocating piston type.
2. Description of the Related Art
Various pumps have been developed over the years for use in discharging fluid under pressure. Many such pumps produce a discharge of the fluid using reciprocating movements of a piston in two general directions. Accordingly, an initial suction stroke of the piston inducts fluid though an inlet opening into one chamber, and a subsequent movement of the piston in the opposite direction transfers that liquid into a smaller second chamber and out through a discharge port. In addition to inducting fluid into the first chamber as described above, subsequent strokes of the piston will decrease the volume of the second chamber forcing fluid in the second chamber out through the discharge port.
Additionally, in many such pumps an expansible packing is provided. One such packing may be provided to surround the piston between the two chambers, and another expansible packing may be provided to surround the piston rod adjacent the opposite end of the second chamber. Furthermore, in the Wagner pump well known to those in the art, a spring is compressed between the two packings, which exerts axial pressure sufficient to expand them into sealing engagement with the piston, piston rod, and the surrounding casings. However, the force exerted by such a spring is not capable of being altered without disassembly of the pump and replacement of the spring.
It is desirable to be able to alter the force exerted by the spring. This is because the pressure under which liquids or slurries are to be discharged from such pumps varies depending on the viscosity of the liquid or slurry, the finish to be imparted to the work piece, and other factors. To avoid excessive wear on the piston, piston rod, and surrounding casing, it is desirable to decrease the axial pressure exerted by the spring when low discharge pressures are preferred (as in the case of relatively thin liquids or slurries), and to increase the pressure when high discharge pressures are preferred (as in the case of viscous liquids or slurries).
In U.S. Pat. No. 4,775,303 (“the '303 patent”) to the same inventor of the present invention, a pump is provided with means for varying the compression of a spring disposed between the packings. The compression can be varied via adjustment of an element with rods and plates, with the element being accessible exterior to the pump. However, the pump of the '303 patent requires standoffs at the upper portion, which are provided to allow access to an adjustment collar. This results in a pump that may be too tall and too large for some applications. In many applications, it is desirable to provide a pump that is shorter and more compact.

SUMMARY OF THE INVENTION

The present invention seeks to provide a reciprocating type pump and method with an improved and customizable approach to varying axial pressure, with the pump and method being durable, compact, and utilizing fewer parts than other such pumps known in the art. In at least one embodiment according to the present invention, a pump is provided comprising a pump body, a piston reciprocally moveable within a bore of the pump body in response to a piston drive, and an axially spaced apart packing means radially expansible in response to axial pressure exerted on the packing means. A packing nut is also provided, which is disposed at the end of said pump opposite said piston drive for adjustably exerting axial pressure on the packings.
In another embodiment according to the present invention, a pump system is provided comprising a pump body, a piston reciprocally moveable within a bore of the pump body in response to a piston drive, a drive motor for providing the piston drive, and axially spaced apart packing means radially expansible in response to axial pressure exerted on the packing means. Springs are also provided, which are disposed between the axially spaced packing means. Further, a packing nut is disposed at the end of the pump opposite the piston drive for adjustably exerting axial pressure on the packings.
In another embodiment according to the present invention, a method is provided for a reciprocating pump system. The method comprises providing a pump body, providing a piston reciprocally moveable within a bore of the pump body, providing a drive motor for moving the piston, and providing axially spaced apart packing means that are radially expansible in response to axial pressure, and exerting varying axial pressure on the packing means. Further, a packing nut is disposed at the end of the pump opposite the piston drive, with the axial pressure on the packings adjustable by tightening or loosening the packing nut.
These and other further features and advantages of the invention will be apparent to those skilled in the art from the following detailed description, taken together with the accompanying drawings, in which:

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a longitudinal section view of a pump according to one embodiment of the present invention;

FIG. 2 is a transverse cross-section of the pump in FIG. 1 taken along section line 2-2;

FIG. 3 is a detailed transverse view of the piston check valve portion of the pump of FIG. 1;

FIG. 4 is a perspective view of one embodiment of a male adaptor according to the present invention;

FIG. 5 is a cross-section view of a male adaptor taken along section line 5-5 of FIG. 4;

FIG. 6 is a perspective view of another embodiment of a male adaptor according to the present invention;

FIG. 7 is a cross-section view of a male adaptor taken along section line 7-7 of FIG. 6;

FIG. 8 is a perspective view of one embodiment of a female adaptor according to the present invention;

FIG. 9 is a cross-section view of a female adaptor taken along section line 9-9 of FIG. 8;

FIG. 10 is an elevation view of one of the series of rings forming a seal according to one embodiment of the present invention; and

FIG. 11 is a cross-section view of a ring taken along section line 11-11 of FIG. 10.

DETAILED DESCRIPTION OF THE INVENTION

The following description presents several possible embodiments. This description is not to be taken in a limiting sense, but is made merely for the purpose of describing the general principles of the invention, the scope of which is further understood by the appended claims.
The present invention generally provides a reciprocating type pump for the discharge of a variety of slurries or liquids. This pump, among other advantages, allows for the axial pressure on various packings to be easily adjusted such that a variety of slurries or liquids, ranging from thin to thick, may more easily pass through the pump mechanism. Other advantages of the adjustable reciprocating pump according to the present invention include being: durable, incomplex, compact, externally adjustable, and customizable to a variety of desired applications.
FIG. 1 shows one embodiment of an improved reciprocating piston type pump 10 according to the present invention. Pump 10 and many of its components are preferably formed from metal, although it is understood other suitable, durable materials may also be used in accordance with the present invention. Pump 10 comprises an outer cylindrical pump body 12 having a discharge manifold 14 at its upper end. Reciprocally disposed within the pump body 12 is a piston 16, having an upper end 18 projecting from the pump body and including a cross pin 19 for connecting the piston to a drive motor (not shown).
The lower portion of the piston 16 defines an inlet chamber 20 carrying a first check ball assembly 22 with a check ball 23 as is well known in the art, which is in communication with a discharge passage 24. Check ball 23 is caged in first check ball assembly 22 for limited movement, and is adjacent to inlet chamber 20. As shown in FIG. 2, a disc-like structure 25 may be incorporated at the upper end of check ball assembly 22 for further limiting the movement of ball 23. Pins (not shown) may further be included within assembly 22 for further caging ball 23 and restricting its movement. The disc-like structure 25 may also be apertured as at 27. Further, a nut and bolt assembly 29 may be frictionally retained in structure 25, with assembly 29 being adjustable to vary the movement permitted by ball 23.
The cylindrical pump body 12 in FIG. 1 also includes a generally cylindrical inner surface 26 spaced apart radially from an outer surface 28 of the piston 16. Disposed within the annular space between the outer surface 28 of the piston 16 and the inner 26 surface of the pump body 12 is a piston seal assembly 30 comprising longitudinally spaced apart upper and lower packing means 32, 34. Upper and lower packing means 32, 34 comprise, respectively, a series of chevron-shaped packing rings 36, 38. The packing means may be comprised of a number of suitable materials, including various metals, metal alloys, rubber, graphite, plastic, or the like. The upper and lower packing means 32, 34 are separated by a sleeve 40 having an upper end 42 bearing against the lower extremity of the upper packing means 32 and a lower end 44 bearing against the upper extremity of the lower packing means 34. The sleeve 40 is slotted so as to permit the passage of fluid from a conduit 46 defined by the piston to a conduit 48 defined by the pump body and in communication with an outlet 50 formed in the discharge manifold 14.
The upper end of the upper packing means 32 is restrained by a female adapter 52 fixed within the pump body, and the lower end of 32 or the upper end of packing means 34 may be restrained by a male adapter 53 fixed within the pump body. FIGS. 4-7 depict possible embodiments of male adapters that may be incorporated into either packing means 32 or 34 according to the present invention for aiding in the compression of the packing means. The male adapter 80 of FIGS. 4-5 is a simpler annular structure, with a male end 82 for fitting snugly within the indent of chevron-shaped packing rings 36, 38. The male adapter 90 of FIGS. 6-7 is also an annular structure with a male end 92 for fitting with packing rings 36, 38. However, adapter 90 also comprises holes 94, which may serve a number of functions, including allowing the passage of a liquid or slurry.
FIGS. 8-9 depict one possible embodiment for a female adapter that may be incorporated into either packings means 32 or 34 according to the present invention. The female adapter is used for aiding in the compression of the packing means. The female adapter 100 is generally an elongated tube structure with female ends 102 for snugly fitting with the pointed end of one or more of the chevron-shaped packings rings 36, 38. While FIGS. 4-9 depict some possible embodiments of male and female adapters according to the present invention, it is understood that other embodiments may also be used within the scope of the present invention.
FIGS. 10-11 depict one embodiment of a packing ring according to the present invention. Packing ring 110 has a generally chevron-shaped cross section 112 as best seen in FIG. 11. The packing ring 110 is designed to be stackable and/or incorporated with the male and female adapters as described above. The pointed end of the chevron-shaped cross section 112 may be fitted into the indented end 116 of another ring 110 or into female ends of a female adapter. Likewise, the indented end of the chevron-shaped cross section 112 may be fitted over the pointed end of another ring 110 or the male end of a male adapter. Although FIGS. 10-11 depict one possible embodiment of a packing ring according to the present invention, it is understood that other types of packing rings may also be used within the scope of the present invention.
In FIG. 1, a packing nut 54 having an upper end 56 shaped to conform with the chevron shape of the lower end of the lower packing means 34 is threadedly received by the pump body 12 at its lower end. It will be seen that tightening of the packing nut 54 advances the packing nut upwardly within the pump body so as to exert an axial pressure on the upper and lower packing means to expand the packing rings into sealing engagement with the outer surface of the piston and the inner surface of the pump body. As can also be seen in FIG. 3, the packing nut 54 defines an inlet chamber 58 within which is disposed a second check valve assembly 60 comprising a check ball 62, a seat 64 sealingly engageable by the check ball 62 and a ball cage or retainer 66 for housing the check ball and limiting its vertical movement.
The packing nut 54 further includes radially spaced apart recesses 68 for receiving an adjustment tool (not shown) for rotating the packing nut as needed to sealingly load the upper and lower packing means. The packing nut 54 further includes exterior threads 70 at the lower end thereof for connection to a fluid suction hose (not shown).
Furthermore, compression springs 72, such as Belleville springs, may be included as part of the assembly between the packing means 32, 34. Such springs provide certain advantages, including but not limited to: preloading of the packing means; compensation for packing ring wear; and, swelling and/or dimensional instabilities.
The pump of the present invention has a number of advantages over other reciprocal pump type mechanisms. For example, in other similar pumps, an adjustment collar for adjustment of the packing means is located at the top of the pump assembly. Standoffs were required at the top of the pump assembly to provide access to the adjustment collar. This arrangement can take up a great deal of space, making the pump assembly taller and less compact than that of the present invention. By placing the packing nut 54 of the present pump at the lower end of the pump, the necessity of standoffs in the earlier pumps is eliminated. The elimination of the standoffs and adjustment collar simplifies the adjustment process and results in a more compact and shorter assembly.
As a result of eliminating such standoffs and an adjustment collar, the number of parts needed for an adjustable pump is reduced. The packing nut 54 can advantageously perform a number of functions, including: adjustment of the axially directed sealing forces of the packing means; retention of the lower check ball assembly; and, connection to the suction hose. Furthermore, the number of seals required has also been reduced in comparison to prior reciprocal pump assemblies.
In operation, the packing nut 54 is preset by rotating it with respect to the pump body so as to vary the compression of the packing means 32, 34 and the springs 72 (if included) according to the magnitude of the pressure under which fluid is to be discharged from the pump. The compression of the packing means and springs is increased as the pressure to be developed is increased (such as with thicker liquids or slurries) and/or any adjustment is required due to packing wear. The compression of the packings means and springs is decreased when less pressure is need, such as with thinner liquids or slurries.
During the initial suction stroke of the piston 16, fluid is drawn into the inlet opening 20, which is immersed in the fluid to be pumped. Then, during the discharge stroke of the piston, the fluid drawn into the inlet through the check assemblies is transferred through the central passage 46 of the piston into the discharge passage 24. Thereafter, during suction strokes fluid in the discharge manifold 14 is discharged through the discharge port 50 as fluid is being drawn into the inlet opening 20 and during discharge strokes fluid is discharged from inside the piston 16 through the passage 24 and port 50.
Although the present invention has been described in considerable detail with reference to certain preferred configurations and methods, other versions are possible. The invention can be used in many different applications. Different materials, configurations, sizes, adaptors, packing ring arrangements and so forth may be used while still adhering to the present reference. Therefore, the spirit and scope of the above description should not be limited to the versions described above.

Claims

1. A pump comprising:

a pump body;

a piston reciprocally moveable within a bore of said pump body in response to a piston drive;

axially spaced apart packing means radially expansible in response to axial pressure exerted on said packing means; and

a packing nut disposed at the end of said pump opposite said piston drive for adjustably exerting axial pressure on said packings.

2. The pump of claim 1, further comprising one or more springs disposed between said axially spaced apart packing means.

3. The pump of claim 1, wherein said pump body further comprises a discharge manifold at its upper end.

4. The pump of claim 3, wherein a liquid or slurry enters the pump through an inlet proximate said packing nut and exits said pump through said discharge manifold.

5. The pump of claim 1, wherein the upper end of said piston comprises a cross pin for connection to a drive motor.

6. The pump of claim 1, wherein said piston further comprises at least one check valve assembly comprising an inlet opening and a discharge opening.

7. The pump of claim 6, wherein said check valve assembly further comprises a check ball.

8. The pump of claim 1, wherein said pump body further comprises a cylindrical inner surface spaced radially apart from an outer surface of said piston.

9. The pump of claim 8, wherein said packing means are disposed between said inner surface of the pump and said outer surface of said piston.

10. The pump of claim 1, wherein said packing means are comprised of one or more chevron-shaped packing rings, said rings stackable on one another.

11. The pump of claim 1, wherein said packing means comprise an upper portion and a lower portion separated by a sleeve.

12. The pump of claim 1, wherein either end of the packing means may be restrained by a female or male adapter.

13. A pump system comprising:

a pump body;

a drive motor for providing said piston drive;

axially spaced apart packing means radially expansible in response to axial pressure exerted on said packing means;

one or more springs disposed between said axially spaced packing means; and

14. The pump system of claim 13, wherein said one or more springs are provided for preloading said packing means and compensating for packing wear, swelling and/or dimensional instabilities.

15. The pump system of claim 13, wherein said packing nut may be rotatably tightened or loosened to vary the axial pressure of said packing means.

16. The pump system of claim 13, wherein said pump body further comprises a discharge manifold at its upper end.

17. The pump system of claim 13, wherein said packing means further comprises an inlet chamber, said piston further comprises at least one check valve assembly and a first conduit, said pump body further comprises a second conduit in communication with said first conduit, and said pump body further comprises a discharge manifold comprising an outlet.

18. The pump system of claim 17, wherein a liquid or slurry enters the pump system through said inlet chamber, flows through said at least one check valve assembly into said first conduit and then through said second conduit, and exits said pump system through said outlet.

19. The pump system of claim 17, wherein said at least one check valve assembly further comprises a check ball.

20. The pump system of claim 13, wherein said packing means are disposed between an inner surface of said pump and an outer surface of said piston.

21. The pump system of claim 13, wherein said packing means are comprised of one or more stackable, chevron-shaped packing rings.

22. The pump system of claim 13, wherein said packing nut comprises one or more recesses for receiving an adjustment tool for rotating said nut.

23. A method for a reciprocating pump system comprising:

providing a pump body;

providing a piston reciprocally moveable within a bore of said pump body;

providing a drive motor for moving said piston;

providing axially spaced apart packing means that are radially expansible in response to axial pressure, and exerting varying axial pressure on said packing means; and

providing a packing nut disposed at the end of said pump opposite said piston drive, adjusting the axial pressure on said packings by tightening or loosening said packing nut.

24. The method of claim 23, further comprising providing one or more springs between said axially spaced packing means, with the springs preloading said packing means and compensating for packing wear, swelling and/or dimensional instabilities.

25. The method of claim 23, further comprising pumping a liquid through said pump system, such that said liquid is drawn into an inlet of said pump system via a suction stroke, and said liquid is transferred through said piston and out a discharge port via a discharge stroke.