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:
[0001]    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 
       [0002]    1. Field of the Invention 
         [0003]    This invention relates to an improvement in pumps and more particularly to those of the reciprocating piston type. 
         [0004]    2. Description of the Related Art 
         [0005]    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. 
         [0006]    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. 
         [0007]    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). 
         [0008]    In U.S. Pat. No. 4,775,303 (“the &#39;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 &#39;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 
       [0009]    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. 
         [0010]    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. 
         [0011]    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. 
         [0012]    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 
         [0013]      FIG. 1  is a longitudinal section view of a pump according to one embodiment of the present invention; 
           [0014]      FIG. 2  is a transverse cross-section of the pump in  FIG. 1  taken along section line  2 - 2 ; 
           [0015]      FIG. 3  is a detailed transverse view of the piston check valve portion of the pump of  FIG. 1 ; 
           [0016]      FIG. 4  is a perspective view of one embodiment of a male adaptor according to the present invention; 
           [0017]      FIG. 5  is a cross-section view of a male adaptor taken along section line  5 - 5  of  FIG. 4 ; 
           [0018]      FIG. 6  is a perspective view of another embodiment of a male adaptor according to the present invention; 
           [0019]      FIG. 7  is a cross-section view of a male adaptor taken along section line  7 - 7  of  FIG. 6 ; 
           [0020]      FIG. 8  is a perspective view of one embodiment of a female adaptor according to the present invention; 
           [0021]      FIG. 9  is a cross-section view of a female adaptor taken along section line  9 - 9  of  FIG. 8 ; 
           [0022]      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 
           [0023]      FIG. 11  is a cross-section view of a ring taken along section line  11 - 11  of  FIG. 10 . 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0024]    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. 
         [0025]    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. 
         [0026]      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). 
         [0027]    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 . 
         [0028]    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 . 
         [0029]    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. 
         [0030]      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. 
         [0031]      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. 
         [0032]    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. 
         [0033]    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). 
         [0034]    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. 
         [0035]    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. 
         [0036]    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. 
         [0037]    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. 
         [0038]    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 . 
         [0039]    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.