Abstract:
A clean out assembly for a centrifugal pump, particularly, for example, a self-priming-type of centrifugal pump, is structured to provide easy adjustment of the clean out assembly and axial movement of a wear plate in proximity to the impeller of the pump without the need for tools to effect such movement of the wear plate and clean out assembly.

Description:
CROSS-REFERENCE TO RELATED APPLICATION  
       [0001]     This application is a non-provisional application claiming priority to provisional patent application Ser. No. 60/707,006 filed Aug. 10, 2005. 
     
    
     BACKGROUND OF THE INVENTION  
       [0002]     1. Field of the Invention  
         [0003]     This invention relates to self-priming centrifugal pumps, and relates specifically to a clean-out assembly for a self-priming pump that facilitates access to the interior of the pump and axial adjustment of the wear plate relative to the impeller.  
         [0004]     2. Description of Related Art  
         [0005]     Self-priming centrifugal pumps are well-known and frequently used in industries where processing fluids with entrained solids is required. Self-priming pumps, also known as trash pumps, are characterized as having a casing which houses a suction chamber and a separation chamber divided by a wall or plenum. An impeller positioned in a volute section of the pump receives fluid from the suction chamber and delivers it by centrifugal action into the separation chamber where it is eventually expelled through an outlet.  
         [0006]     The impeller of self-primer pumps are generally of the open type, meaning that the impeller has a rear shroud, but an open eye into which fluid flows from the suction chamber. In order for the pump to operate most efficiently, the impeller must be positioned as close as possible to the wall of the volute casing of the pump to minimize recirculation and leakage of fluid out and around the impeller. To accomplish that, a wear plate is typically positioned between the volute casing and the open or suction side of the impeller. The wear plate is positioned in very close proximity to the impeller vanes to assure efficient pump operation.  
         [0007]     As the pump is operated, especially in the processing of fluids with entrained solids, the vanes of the impeller and/or the wear plate can become worn down by the solids and the resulting gap or clearance between the impeller vanes and wear plate causes the pump to operate with less efficiency. It then becomes necessary to adjust the distance or clearance between the impeller and the wear plate to assure a close fit therebetween.  
         [0008]     Pump manufacturers have dealt with this problem in the prior art by providing various means by which the clearance between the impeller and the wear plate can be adjusted as needed. In old prior art systems, an adjustment was provided for axial movement of the rotating assembly (i.e., impeller and drive shaft) relative to a stationary wear plate or pump casing. However, such adjustment means involved the need to correspondingly adjust the drive shaft relative to the motor, and involved other compensatory adjustments to structural elements of the pump.  
         [0009]     In certain types of pumps, exemplified by self-primer pumps, a clean out assembly is provided which serves two essential purposes. First, the clean out assembly provides access to the eye of the impeller through the suction chamber and provides a convenient means for removing solids or other debris that may have clogged the impeller. Second, the clean out assembly has provided a supporting structure for the wear plate and, consequently, a means for adjusting the axial distance between the wear plate and impeller.  
         [0010]     In presently known clean out assemblies having means for adjusting the wear plate, the adjustment means or devices are complicated, usually requiring several adjustment and securement devices, and all require tools for removing and/or adjusting the several elements to effect an adjustment of the wear plate. As a result, adjusting the wear plate can be difficult and time consuming, and the several elements that comprise the adjustment mechanism increase the cost of the pump.  
         [0011]     Thus, it would be advantageous to provide a clean out assembly that provides adjustment of the wear plate, but which requires no tools to effect the adjustment of the wear plate or to remove the clean out assembly for servicing of the pump, thereby also simplifying manufacture of the pump and reducing the cost of manufacture.  
       BRIEF SUMMARY OF THE INVENTION  
       [0012]     In accordance with the present invention, a clean out assembly for a pump, particularly a self-primer-type centrifugal pump, is structured to provide support for a wear plate and to provide a tool-free means for not only axially adjusting the wear plate relative to the impeller of the pump, but to facilitate removal of the clean out assembly for servicing the impeller of the pump. As used herein, “tool-free” means that no tools are required to effect movement or adjustment of the described elements of the clean out assembly and that such movement is achieved by using one&#39;s hand to effect such adjustment or movement.  
         [0013]     The clean out assembly of the present invention generally comprises an end cover which provides support for a wear plate and is positioned to cover the access opening in a centrifugal pump axial to the eye of the impeller. The end cover supports a wear plate that is positioned in close proximity to the impeller when the end cover is secured in place within the pump casing. The end cover is attached is the pump casing by securement apparatus.  
         [0014]     The end cover, and thus the wear plate, is axially adjustable relative to the pump casing and the impeller by adjustment elements that operate separately from the securement apparatus for attaching the end cover to the pump casing and, in an especially suitable embodiment may be spaced from the securement apparatus. By providing adjustment elements operably separate from the securement means, axial adjustment of the wear plate is significantly simplified over conventionally-known clean out assemblies for pumps.  
         [0015]     The adjustment elements comprise a threaded shaft that is threadingly positioned through openings in the end cover. The adjustment elements also have a handle which can be turned by hand to effect adjustment of the end cover relative to the pump casing, and thus effect axial adjustment of the wear plate relative to the impeller. The securement apparatus for attaching the end cover to the pump casing are also each provided with hand nuts that enable tightening of the securement apparatus by hand. No tools are required to effect attachment or adjustment of the end cover relative to the pump casing, as is conventional in the prior art.  
         [0016]     The simplified structures of the present clean out assembly enable axial adjustment of the end cover and wear plate without the need for tools, and enable axial adjustment without removal of any parts. The configuration of the present clean out assembly effectively reduces the manufacturing and operating costs of the pump.  
     
    
     BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS  
       [0017]     In the drawings, which illustrate what is currently considered to be the best mode for carrying out the invention:  
         [0018]      FIG. 1  is a perspective view of a prior art pump illustrating conventional structure for a clean out assembly;  
         [0019]      FIG. 2  is a view in cross section of the prior art clean out assembly shown in  FIG. 1 ;  
         [0020]      FIG. 3  is a perspective view of a pump illustrating the clean assembly of the present invention; and  
         [0021]      FIG. 4  is a view in cross section of the clean assembly of the present invention as shown in  FIG. 3 . 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0022]     By way of comparison, a prior art clean out assembly  10  is illustrated in  FIGS. 1 and 2  which comprises, in general, an end cover  12  and a supporting ring  14  spaced from the end cover  12  by a plurality of stanchions  16 . The supporting ring  14  provides a means for attachment thereto of a wear plate  18 , which is connected to the supporting ring  14  by screws  20 . The clean out assembly  10  fits into an opening  22  formed in the pump casing  24  so that the wear plate  18  is positioned adjacent the impeller  25 , as best seen in  FIG. 2 .  
         [0023]     In the prior art pump of  FIG. 1 , the clean out assembly  10  is connected to the pump casing  24  by a plurality of threaded studs  26  that extend through holes  28  formed in the end cover  12 . The end cover  12  is secured in place by hand nuts  30  that tighten onto the threaded studs  26 .  
         [0024]     The means for adjusting the axial position of the wear plate  18  relative to the impeller is also associated with the means for attaching the end cover  12  to the pump casing  24 . Specifically, a threaded adjustment member  34  threads into each opening  28  in the end cover  12  and slips onto the threaded stud  26 . The adjustment member  34  has a hexagonally-configured head the corners of which engage with teeth formed in a central opening  38  of a locking member  36 . The opening  38  of the locking member  36  is sized to receive the head of the adjustment member  34 .  
         [0025]     The locking member  36  is normally bolted to the end cover  12  by the positioning of a locking bolt  40  and washer  42  through an opening  44  in the locking member  36 . The locking bolt  40  then threads into an opening  46  in the end cover  12 . When the axial position of the wear plate  18  is to be adjusted (i.e., the axial position of the clean out assembly is to be adjusted relative to the pump casing  24 ), the hand nut  30  must first be removed from the threaded stud  26 . The locking member  36  is then removed from the end cover  12  by using a first tool to loosen and remove the locking bolt  40  and nut  44 .  
         [0026]     Each adjustment member  34  is then rotated a selected amount to move the end cover  12  toward the pump casing  24 . A tool different from the tool used to remove the locking bolt  40  is used for that process. Once the adjustment members  34  are rotated the desired amount, the locking member  36  is replaced about the head of the adjustment member  34  and is locked in place by securement of the locking bolt  40  into place. Each of these steps requires various tools for effecting the adjustment, and the adjustment involves manipulation of several structural elements, all of which results in time-consuming and costly servicing and added cost for manufacturing of the pump.  
         [0027]     The clean out assembly  50  of the present invention, shown in  FIGS. 3 and 4 , solves the problems encountered with prior art clean out assemblies by providing a simplified and tool-free means for attaching the clean out assembly to the pump casing and for effecting adjustment of the wear plate. Further, the clean out assembly of the present invention provides means for attachment of the end cover to the pump casing which is separate from the axial adjustment structure, thereby eliminating the need to remove structural elements associated with attachment of the end cover as is required in the prior art.  
         [0028]     The clean out assembly  50  of the present invention comprises an end cover  52  and a supporting ring  54  to which a wear plate  56  is attached by some means, such as bolts  58 . The supporting ring  54 , and thus the wear plate  56 , is spaced from the end cover  52  by a plurality of spacer columns  60 . The clean out assembly  50  fits into an opening  62  in the pump casing  64  in the conventional manner to position the wear plate  56  in very close proximity to the impeller  61 , as best seen in  FIG. 4 .  
         [0029]     The end cover  52  of the present invention is secured adjacent the shoulder  66  surrounding the opening  62  in the pump casing  64  by securement apparatus comprising a plurality of threaded stud bolts  68  that extend through openings  70  in the end cover  52 . A threaded hand nut  72  is attachable to each stud bolt  68  providing a means for tightening the end cover  52  to the pump casing  64 .  
         [0030]     Axial adjustment of the wear plate  56  in the present invention is effected by providing two or more adjustment elements  78  that comprise a threaded shaft  80  and a handle  82 . The threaded shaft  80  of the adjustment element  78  is threaded through a threaded opening  84  in the end cover  52 . As best seen in  FIG. 4 , the adjustment element  78  is set so that the terminal end  86  of the threaded shaft  80  seats against the shoulder  66  of the pump casing  64 . As will become apparent for axial adjustment purposes, the end cover  52  is initially positioned relative to the shoulder  66  of the opening  62  in the pump casing  64  such that a space  88  is provided between the shoulder  66  and the end cover  52 .  
         [0031]     When adjustment of the wear plate  56  is required (i.e., when the wear plate  56  needs to be brought into closer proximity to the impeller  61 ), the hand nuts  72  on the stud bolts  68  are loosened slightly by hand to allow movement of the end cover  52 . The handle  82  of each adjustment element  78  is then rotated by hand to effect movement of the end cover  52  in a direction toward the pump casing  64 , and thus effect axial movement of the wear plate  56  toward the impeller  61 . Movement of the end cover  52  is accomplished by the fact that the threaded shaft  80  of the adjustment elements  78  are threaded into the threaded openings  84  in the end cover  52 ; consequently, rotation of the handles  82  causes the end cover  52  to move in a direction toward the impeller  61 .  
         [0032]     Once the wear plate  56  is adjusted to the desired point of proximity to the impeller  61 , the hand nuts  72  are then turned by hand to tighten the end cover  52  again to the pump casing  64 . The adjustment elements  78  of the invention are structured with self-locking threads that lock the adjustment elements  78  into place after movement. However, a locking element of known structure may also be employed to secure the adjustment elements  78  in place. Indicia  90  may also be provided on the adjustment elements  78  to calibrate the amount by which the axial adjustment is made.  
         [0033]     It can be appreciated from the foregoing disclosure that the clean out assembly of the present invention provides an improved and simplified means of securing the clean out assembly to the pump casing and effecting axial adjustment of the wear plate relative to the impeller, while reducing the costs of manufacture and operation of the pump. The structure, configuration and placement of the adjustment elements may vary from that illustrated and described herein. For example, while illustrated and described herein as being spaced from the stud bolts that secure the end cover to the pump casing, the adjustment elements may be located in proximity to the stud bolts, but operate separately from the stud bolts in a manner similarly described herein for effecting axial movement of the end cover, and without the need for tools. Accordingly, reference herein to particular details of the clean out assembly of the present invention are by way of example, and not by way of limitation.