Abstract:
A pump assembly supportable in a tank having an opening includes a pump such as a grinder pump and a cover attachable to the pump. The cover has a peripherally-extending portion extending outwardly from the pump and the peripherally-extending portion is sized to rest on a first surface of the portion of the tank defining the opening. A quick-release latching mechanism may include a plurality of members such as arms or pawls which are movable generally radially between a retracted position wherein the outer ends of the plurality of members are disposed inwardly of the peripherally-extending portion of the cover allowing the pump assembly to be lowered into the opening in the tank, and an extended position wherein the outer ends of a plurality of members are positionable against a second opposite side of the portion of the tank defining the opening to compress the portion of the tank forming the opening between the cover and the plurality of members.

Description:
CLAIM TO PRIORITY AND CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application claims the benefit of U.S. Provisional Application No. 60/917,844, filed May 14, 2007, entitled “Grinder Pumps And Components Therefor,” the entire subject matter of which is hereby incorporated herein by reference. 
         [0002]    This application is also related to commonly owned pending U.S. Utility patent application Ser. No. 11/748,231 filed May 14, 2007, entitled “Wireless Liquid Level Sensing Assemblies And Grinder Pump Assemblies Employing The Same” by Capano et al., and commonly owned pending U.S. Design patent application Ser. No. 29/280,014 filed May 14, 2007, entitled “Grinder Pump Assembly” by Henry et al. The entire subject matter of these applications are hereby incorporated herein by reference. 
     
    
     FIELD OF THE INVENTION 
       [0003]    This invention relates generally to grinder pumps, and more particularly to latching assemblies for grinder pumps. 
       BACKGROUND OF THE INVENTION 
       [0004]    Grinder pumps are often used in low pressure sewage systems for pumping sewage. A grinder pump is typically disposed in a sewage tank in which the grinder pump includes a motor for driving a grinder mechanism for cutting or grinding solids or semisolid matter in the sewage and a pump for pumping the processed sewage. Grinding solids and/or semisolid matter in the sewage allows the resulting particulate effluent to be transferred using a pump through relatively small diameter pipes without clogging. 
         [0005]    Conventionally, grinder pumps are produced in two configurations, namely, an open wet well configuration and a closed wet well configuration. 
         [0006]    In an open wet well configuration, a grinder pump is positioned inside a tank. The entire volume under the tank lid is considered as a single storage vessel for the wastewater that flows in and is periodically pumped out, i.e., there is no partition between the top and the bottom of the tank. Often the grinder pump is supported from the bottom of the tank on a stand. 
         [0007]    In a closed wet well configuration, the grinder pump is located in a lower chamber of the tank that contains the wastewater flow. An upper chamber or accessway of the tank provides a passageway for the grinder pump to be installed and removed as needed. The accessway extends from the tank lid at grade level or ground level down to the upper plane of the wet well chamber. Typically in closed wet well configuration, an inwardly extending horizontal flange extends from the tank at the top of the wet well and has an opening large enough to accept the lower section of the grinder pump. The grinder pump assembly is suspended in the tank from an outwardly extending horizontal flange on the top of the grinder pump that rests on the inwardly extending horizontal flange of the tank. With the grinder pump in place, the outwardly extending horizontal flange of the grinder pump engages an inwardly extending horizontal flange of the tank around the aperture to create a continuous bulkhead separating the wet well from the accessway. Typically, often as many as twelve threaded fasteners are used to securely hold the grinder pump in place as well as provide the compressive force needed to effect a seal between the flange on the grinder pump and flange in the tank. 
         [0008]    There is a need for improved grinder pumps, and particularly, means for securing and sealing the grinder pumps in closed wet well grinder pump stations. 
       SUMMARY OF THE INVENTION 
       [0009]    In a first aspect, the present invention provides a pump assembly supportable in a tank having an opening. The pump assembly includes a pump, a cover attachable to the pump, the cover having a peripherally-extending portion extending outwardly from the pump and the peripherally-extending portion sized to rest on a first surface of a portion of the tank defining the opening, and a plurality of members movable generally radially between a retracted position wherein outer ends of the plurality of members are disposed inwardly of the peripherally-extending portion of the cover allowing the pump assembly to be lowered into the opening in the tank, and an extended position wherein the outer ends of the plurality of members are positionable against a second opposite side of the portion of the tank defining the opening to compress the portion of the tank forming the opening between the cover and the plurality of members. 
         [0010]    In a second aspect, the present invention provides a pump assembly supportable in a tank having an opening. The pump assembly includes a pump, a cover attachable to the pump, the cover having a bottom surface supportable on an upper surface of a portion of the tank defining the opening, and single quick-release latching means for compressing the portion of the tank forming the opening between the cover and a plurality of movable members. 
         [0011]    In a third aspect, the present invention provides a grinder pump assembly supportable in a tank having an opening. The grinder pump assembly includes a grinder pump and a cover attachable to the grinder pump. The cover has a peripherally-extending portion extending outwardly from the grinder pump and the peripherally-extending portion sized to rest on a first surface of a portion of the tank defining the opening. A seal is attached to a bottom surface of the peripherally-extending portion of the cover for engaging the first surface of the portion of the tank defining the opening. A top housing has an upper end and a lower end, and the lower end is attachable to the pump and the upper end is attachable to the cover. A quick-release latching mechanism includes a rotatable member having an axis extending through the cover, a hub attached to the rotatable member, and a plurality of members having inner ends operably connected to the hub and movable generally radially between a retracted position wherein curved outer ends of the plurality of members are disposed inwardly of the peripherally-extending portion of the cover allowing the pump assembly to be lowered into the opening in the tank, and an extended position wherein the outer ends of a plurality of members are positionable against a second opposite side of the portion of the tank defining the opening to compress the portion of the tank forming the opening between the cover and the plurality of members. 
         [0012]    In a fourth aspect, the present invention provides method for releasably supporting a pump in a tank having an opening. The method includes providing a pump, providing a cover attachable to the pump, introducing the pump through an opening in the tank, releasably supporting the cover on a upper side of a portion of the tank forming the opening with the pump extending below the portion of the tank forming the opening, and radially extending outer ends of a plurality of members against a lower surface of the tank defining the opening to compress the portion of the tank forming the opening between the cover and the outer ends of the plurality of members. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0013]    The subject matter which is regarded as the invention is particularly pointed out and distinctly claimed in the concluding portion of the specification. The invention, however, may best be understood by reference to the following detailed description of various embodiments and the accompanying drawings in which: 
           [0014]      FIG. 1  is an elevational view of one embodiment of a grinder pump station employing a latching mechanism in accordance with the present invention in which a grinder pump system is disposed in an opening in a tank; 
           [0015]      FIG. 2  is an exploded perspective view of the latching mechanism of the grinder pump station of  FIG. 1 ; 
           [0016]      FIG. 3  is a bottom view of the latching mechanism and cover of  FIG. 2  in an extended or locked position; 
           [0017]      FIG. 4  is a bottom view of the latching mechanism and cover of  FIG. 2  in a retracted or unlocked position; 
           [0018]      FIG. 5  is an enlarged top view of one of the plurality of members or pawls of the latching mechanism of  FIG. 2 ; 
           [0019]      FIG. 6  is an enlarged side elevational view of the member or pawl of  FIG. 5 ; 
           [0020]      FIG. 7  is a bottom perspective view of a prior art cutting wheel for a grinder pump; 
           [0021]      FIG. 8  is a side elevation view of the prior art cutting wheel of  FIG. 7 ; 
           [0022]      FIG. 9  is a bottom perspective view of one embodiment of a cutting wheel in accordance with the present invention for use in a grinder pump; and 
           [0023]      FIG. 10  is a side elevation view of another embodiment of a cutting wheel in accordance with the present invention. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0024]    One aspect of the present invention is directed to quick-release latching mechanisms for securely retaining grinder pump assemblies configured in, for example, a closed wet well and providing adequate compressive force to also effect a watertight seal between the wet well and accessway portions of the tank. 
         [0025]      FIG. 1  illustrates one embodiment of a low-pressure grinder pump station  100  in accordance with the present invention for collecting, grinding, and pumping wastewater. Grinder pump station  100  generally includes a tank  120  and a grinder pump assembly  130 . The grinder pump assembly is supported from the tank by a top housing  132  and a cover  134  in accordance with the present invention. As described below, a latching mechanism may be disposed between the cover and the top housing and used to retain the grinder pump assembly in the tank. Grinder pump station  100  is readily installable in the ground by connecting the station to a wastewater feed pipe  122 , a wastewater discharge pipe  124 , and an electrical power supply via an electrical cable (not shown). The system may also be connected to or include a vent. 
         [0026]      FIG. 2  illustrates an exploded view of one embodiment of a latching mechanism  200 , top housing  132 , and cover  134  in accordance with the present invention. Latching mechanism  200  may include a vertical center spindle  210 , a rotatable member or bolt  220 , a hub base  230 , a plurality of pins  240 , and a plurality of elongated members such as arms or pawls  250 . 
         [0027]    Vertical center spindle  210  is axially restrained and rotatable within a centrally disposed hole in a cover  134 . Disposed through spindle  210  is bolt  220  which may include a hexagonal head that can be driven with conventional tools such as a socket wrench. Hub base  230  includes a centrally located hole and the hub base is secured to the bottom of spindle  210  by a nut (not shown) attached to bolt  220 . Hub base  230  may have a generally triangular shape with holes  232  disposed adjacent each corner. The holes may be disposed at generally the same distance from the center of the hub base. It will be appreciated that a circular shaped hub base or other shaped base may be suitably employed. 
         [0028]    Suitable O-rings may be employed for forming a seal between spindle  210  and the hole in cover  134 . For example, a first O-ring may be disposed between the top flange (around the spindle and of spindle  210  and the top cover  134 ). A second O-ring may be disposed around the spindle and between the bottom of cover  134  and the top of hub base  230 . In another example, the spindle may have one or more circumferentially extending cutouts extending around the spindle for receiving the one or more O-rings therein. In this configuration, the outer surface of the O-rings engages the inside of the center hole in the cover to form a seal. 
         [0029]    Each of the plurality of pawls  250  has a first inner end  252  which includes a hole and an opposite second outer end  254 . The inner ends of the pawls are pivotally attached to the corners of the hub base with the plurality of pins  240 . The elongated pawls are positioned generally horizontally, just above the plane of the hub base within the confines of the cover. 
         [0030]    As shown in  FIG. 3 , the distance from the center of the spindle to the center of the pins  240 , and the length and width of the radially outwardly extending pawls  250  may be sized so that in a fully extended position, each end  254  of the pawl projects outwardly, through a channel formed by a cutout  135  ( FIG. 2 ) formed in cover  134  and a cutout  137  formed in top housing  132 , beyond a point equivalent to the radius of the aperture formed in the inwardly extending horizontal flange  110  ( FIG. 1 ) in tank  120  ( FIG. 1 ). 
         [0031]    As shown in  FIG. 4 , the distance from the center of the spindle to the center of the pins  240 , and the length and width of pawls  250  is also selected so that in a retracted position, when the spindle is rotated in the direction of arrow A, each of ends  254  of pawls  250  are retracted within the cover and within the radius of the aperture in the tank and desirably within the radius of a seal  290 . 
         [0032]    In the retracted position as shown in  FIG. 4 , the grinder pump assembly may be set in place within the opening of the flange of the wet well. Once positioned, the center spindle can be rotated, for example, less than a half revolution, to rotate the hub base with the pins which act as cams to apply a generally horizontal, outwardly directed force on the pawls driving them through their respective channels initially along a chord and toward a radial path and under the lower surface of the flange of the wet well. Once the pawls have been deployed outward under the flange of the wet well, the grinder pump unit is secured in place within the tank. 
         [0033]    As shown in  FIGS. 4 and 5 , the cover may include guides  295  and  296  for guiding the sides of pawls  250  when they are moved between a retracted position and an extended position. 
         [0034]    With regard to  FIGS. 5 and 6 , by forming the ends of pawls  250  with a varying geometry or sloped portion  258 , the amount of torque needed to drive the actuating spindle and the amount of compressive force created on the sealing means may be altered. For example, the curved shape of the ends of the pawls may be selected so that the force required may be lessened by decreasing the slope of the end of the pawl. Further, the curved shape of the ends of the pawls may be selected so that the force or torque required to lock the latching mechanism is relatively constant throughout the rotation of the spindle. The number of pawls can also be varied depending on the needs of the application. 
         [0035]    The mating of these two flanges create a watertight seal capable of withstanding a nominal amount of water pressure in either cavity. For example, the underside of the cover may have a groove in which is received seal  290  such as an extruded foam EPDM (ethylene propylene diene monomer) rubber. The grinder pump assembly is also secured in place to resist motion caused by vibration of the grinder pump assembly, discharge pressures, inflow, etc. 
         [0036]    An advantage of the latching mechanism for use with the installation and removal of a grinder pump assembly in a wet well of a tank, is the ability of a user to attach and release the grinder pump assembly from the tank with a single action, e.g., using a socket wrench. 
         [0037]    Many conventional grinder pump stations having a wet well can have accessways as deep as 12 feet or more feet thereby requiring a service technician to use specialized wrenches that will extend an equivalent distance downward. The deeper the station, the more time consuming it can be to locate each of the upwards of 12 fasteners with the elongated wrench in order to remove or install the grinder pump assembly. Compared to conventional grinder pump stations attached with a plurality of bolts, the present invention as described above, reduces the time and effort required in installing and removing a grinder pump assembly from a tank. 
         [0038]    From the present description, it will be appreciated that the grinder pump assembly may be positioned in a tank having only a wet well, i.e., not having a dry well portion or accessory. 
         [0039]    Another aspect of the present invention is directed to a monolithic or one-piece cutting wheel for a grinder pump cutting mechanism. 
         [0040]    Conventional grinder pump assemblies typically have a cutting mechanism that employs a rotating cutting wheel within a stationary ring. The stationary ring has a large number of cutting surfaces oriented generally axially or perpendicular to the direction of rotation. As shown in  FIGS. 7 and 8 , a typical prior art rotating cutting wheel  10  has a disc-shaped base  12  and separately attachable elongated cutting elements  20 . These cutting elements have sharp cutting edges oriented axially or near axially as well. The cutter wheel&#39;s outside diameter is nearly equivalent in dimension to the stationary ring&#39;s outside diameter assuring the clearance between rotating and stationary cutting edges is kept as small as practical to improve cutting efficiency. The cutting elements are typically produced from a harder, more durable material to withstand the wear of cutting. Since suitable cutting materials will tend to be more expensive, the overall cutting wheel will oftentimes be made from an inexpensive material such as cast iron with the more exotic cutting material such as stainless steel formed into cutting elements and mounted to the cutting wheel. The elongated cutting elements on the rotating wheel agitates the wastewater in the tank during operation. This agitation keeps the solids in suspension during pumping cycles. 
         [0041]      FIG. 9  illustrates one embodiment of a cutting wheel  300  in accordance with the present invention. Cutting wheel  300  includes a disc-shaped base portion  312 , a plurality of cutting elements  320  and a plurality of paddle elements  330 . The paddle elements allow the level of agitation to be controlled independently of the cutting teeth geometry. Cutting elements  320  may be sized smaller than the cutting elements of conventional cutting wheels. 
         [0042]    Cutting wheel  300  may be formed from a single forging which creates the raised cutting elements as well as the paddle elements. Secondary processes such as turning or milling can be used to achieve the dimensional requirements after forging. Other forming processes such as investment casting, sintering, and metal injection molding may be employed as well. The cutting wheel may be fabricated from a suitable corrosion and abrasion resistant material. Hard chrome plating may also be employed to enhance the cutting wheels corrosion and abrasion resistance. Since the cutting edges must withstand wear and erosion over time, they can be selectively hardened, for example, with a method such as induction hardening. 
         [0043]    A benefit of the a single-piece cutting wheel in accordance with the present invention is that the cutting wheel may be made smaller or with tighter tolerances compared to conventional cutting wheels where the cutting elements are attached to a disc-shaped base. For example, in a conventional cutting wheel, the cutting elements that are mounted to the rotating base limits the tolerance to which the outside diameter of the wheel can be held and results in a compromise in achievable clearances between the stationary and rotating cutting elements and negatively impact cutting effectiveness. By forming a monolithic or single-piece cutting wheel with integrally formed cutting elements overcomes the tolerances associated with the attaching of separate cutting elements in conventional cutting wheels. 
         [0044]    In addition, by separating the cutting function from the agitation function, the paddles elements can be oriented with respect to the cutting elements to provide for agitation to keep the solids in suspension, as well as minimizing the localized turbulence at the region of cutting. This minimizes the turbulence that may prevent suspended solids in the wastewater from flowing into the cutting action between the cutting elements of the cutting wheel and the cutting elements of the stationary ring during the pumping cycles. 
         [0045]    For example, the size of the cutting wheel may be about 6 inches in diameter, the cutting elements ⅜ inch high and ½ inch long, and the paddle elements may have a height of ⅛ inch and a width of 1 inch. 
         [0046]      FIG. 10  illustrates another embodiment of a cutting wheel  400  in accordance with the present invention. Cutting wheel  400  includes a base portion  412  having a cross-sectional profile that may improves the flow characteristics past the cutting region between the cutting elements (not shown) of the wheel, and into the inlet of the pump. For example, using gradual radii R instead of a sharp corner profile the inflow between the cutter and the pump inlet can be less disruptive. The combination of the improved cross-sectional profile, paddle elements (not shown) may be provided to allow the grinder pump unit to run more efficiently wasting less energy on excessive agitation and inlet friction head. As described above, cutting wheel  400  may be a monolithic or one-piece cutting wheel. 
         [0047]    In addition, the cutter wheel profile can be optimized to increase the mass moment of inertia of the wheel. This inertia, or flywheel effect, helps to prevent jamming during grinding of rigid or tough materials. 
         [0048]    In conventional grinder pump cutting wheels, the agitation has been a by-product of the size of the cutting elements rather than a purpose-designed attribute. Also, by making the cutting teeth larger to aid in mounting to the rotating wheel or to deliberately increase agitation of the wastewater, excessive, localized turbulence can be created near the rotating cutter teeth thereby making it difficult for suspended solids to flow into the cutting region and be properly macerated. There turbulence may tend to push flow away from the cutting action. Thus, the present invention for a cutting wheel may allow using smaller sized cutting teeth and spaced apart paddle elements may avoid some of the drawbacks of conventional grinder pump cutting wheels. 
         [0049]    Thus, while various embodiments of the present invention have been illustrated and described, it will be appreciated to those skilled in the art that many changes and modifications may be made thereunto without departing from the spirit and scope of the invention.