Abstract:
A pumping unit ( 20 ) includes a hopper assembly ( 24 ) for holding material to be pumped, a pair of identical pumping assemblies ( 26, 28 ), and a pumped material outlet ( 30 ). The assemblies ( 26, 28 ) include directional or spool valves ( 54 ) having rotatable spools ( 76 ), tubular pumping chambers ( 56 ), and pistons ( 122 ) within the chambers ( 56 ). The pistons ( 122 ) include concave operating faces ( 134 ), which are complemental and mate with the outer surfaces of the spools ( 76 ). Operation of the unit ( 20 ) creates successive charges of pumped materials having a minimum of disruptions, such as tearing or smearing.

Description:
BACKGROUND OF THE INVENTION 
     Field of the Invention 
       [0001]    The present invention is broadly concerned with improved pumping units of the type specifically designed for handling of food products, in order to accurately pump such products with a minimum of product disruption, such as smearing or tearing of meat products. More particularly, the invention is concerned with such pumping units, and the pumping assemblies forming a part thereof, which include features assuring minimal product disruptions with high pumping speeds and accurate pumping rates. 
       Description of the Prior Art 
       [0002]    U.S. Pat. No. 5,479,847 describes a highly successful commercial food pump manufactured and sold by Marlen International, Inc. The pump described in the &#39;847 patent includes an upright hopper which receives incoming food materials to be pumped. The materials pass from the hopper into a common internal chamber. A pair of shiftable sleeves within the chamber reciprocate in an alternating, fore-and-aft manner to form respective charges of food materials within each sleeve. As each sleeve is filled, an associated piston is used to force the food charge out of the pump and into an outlet assembly having a central rotatable valve. This pump can thus be operated in a batch-continuous fashion to deliver food products to downstream processing devices. 
         [0003]    In some instances, it has been found that the pump of the &#39;847 patent can lead to tearing or smearing of food products, particularly in the case of meats. This is believed to result from the use of the reciprocating sleeves and pistons, which present relatively sharp edges that can cut or pierce food products during operation. Similarly, the pistons and central outlet valve can create similar issues. It would therefore be desirable to provide an improved food pump which has all of the desirable characteristics of the prior pump, while minimizing product disruptions. 
         [0004]    References describing food pumps include US and foreign Patents and Publications Nos. U.S. Pat. Nos. 3,456,285, 3,887,964, 4,167,374, 4,431,384, 4,863,317, 4,884,594, 5,464,338, 5,474,101, 5,553,985, 5,688,534, 6,467,403, 7,182,224, 7,225,554, 2013/0248026, and GB 1547407, and Busch Machinery product brochure. 
       SUMMARY OF THE INVENTION 
       [0005]    The present invention overcomes the problems outlined above and provides pumping assemblies for use in food or related pumps, which largely resolve food disruption issues. Broadly speaking, such pumping assemblies include an elongated, normally upright, stationary, tubular valve body presenting a material inlet end configured to be coupled with a source of material to be pumped (e.g., a hopper), a material outlet end for directing pumped material to an outlet device, and a pump opening. An elongated, stationary, tubular pumping chamber is operatively connected with the pump opening of the tubular body. A four-port valve spool is located within the tubular body and presents an arcuate outer surface; the spool has a material inlet port, a pumped material outlet port, first and second operating ports, a first passageway interconnecting the first operating port and the material inlet port, and a second passageway interconnecting the second operating port and the material outlet port. A piston is located within the pumping chamber and is shiftable between a fill position, a compression position, and a discharge position. Importantly, the piston has an arcuate face closely complemental with the arcuate outer surface of the spool, which creates a piston cleaning action as the spool rotates; moreover, this eliminates the possibility of product collection between the piston face and spool. 
         [0006]    A drive is operably coupled with the spool for selective shifting of the spool between a pumping chamber fill position where the spool first operating port is in communication with the pumping chamber, and a material discharge position where the second operating port is in communication with the pumping chamber. The piston is operable to shift within the pumping chamber when the spool is in the pumping chamber fill position in order to introduce material into the pumping chamber from the source through the first passageway, and to discharge the material within the pumping chamber through the second passageway when the spool is in the discharge position. 
         [0007]    Additionally, the spool of the preferred pumping assembly has an imperforate surface between the first and second operating ports. This surface is of a size to completely block the pump opening of the tubular body. Accordingly, the spool is shifted to an intermediate position between the fill and discharge positions, in order to allow the piston to recompress a charge of material within the pumping chamber prior to discharge thereof. such pre-compression serves to increase the accuracy of the weight or volume of material to be delivered. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0008]      FIG. 1  is a perspective view of a pumping unit in accordance with the invention, illustrating the output end of the unit; 
           [0009]      FIG. 2  is another perspective view of the pumping unit, depicting the opposite end thereof, as compared with  FIG. 1 ; 
           [0010]      FIG. 3  is a perspective view illustrating the dual pumping assemblies forming a part of the unit; 
           [0011]      FIG. 4  is an exploded view illustrating the internal spool and other components of one of the pumping assemblies; 
           [0012]      FIG. 5  is a vertical sectional view illustrating one of the pumping assemblies during introduction of material to be pumped into the pumping chamber thereof; 
           [0013]      FIG. 6  is a horizontal sectional view of the pumping assembly of  FIG. 5 ; 
           [0014]      FIG. 7  is a vertical sectional view illustrating one of the pumping assemblies during compression of the material within the pumping chamber thereof; 
           [0015]      FIG. 8  is a horizontal sectional view of the pumping assembly of  FIG. 7 ; 
           [0016]      FIG. 9  is a vertical sectional view illustrating one of the pumping assemblies during discharge of material therefrom; 
           [0017]      FIG. 10  is a horizontal sectional view of the pumping assembly of  FIG. 9 ; 
           [0018]      FIG. 11  is a perspective view similar to  FIG. 1 , but depicting the hopper assembly shifted away from the pumping assemblies to allow for maintenance or cleanup; and 
           [0019]      FIG. 12  is a side elevational view of the unit illustrated in  FIG. 11 . 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
       [0020]    Turning now to the drawings, a pumping unit  20  is depicted in  FIGS. 1 and 2  and broadly includes a bifurcated housing assembly  22 , a hopper assembly  24 , and a pair of identical pumping assemblies  26  and  28 . The unit  20  is designed to receive flowable materials, such as meat or other comestible products, and to accurately pump portions of the materials via an outlet  30  for downstream processing. 
         [0021]    The housing assembly  22  is itself conventional, and has leveling feet  32  with internal space to house drives and electrical control circuitry for the overall unit. The hopper assembly  24  includes a pair of identical, upright, conical material hoppers  34  and  36  mounted on a carriage  38 . The latter is supported on side rails  40  and rollers  42 , thereby permitting fore-and-aft shifting of the entire hopper assembly. Each hopper  34 ,  36  has an openable lid  44 , as well as an augur drive assembly  46  for selective rotation of an internal augur  48  within the hopper ( FIG. 5 ). As illustrated, the uppermost margin of the augur flight  49  is equipped with an enlarged synthetic resin tip  49   a;  this minimizes any chance of product entering at the top outside of the flight edge and traveling downward, leaving marks on the product. Each hopper is also equipped with a vacuumizing assembly (not shown) allowing a vacuum to be drawn within the hopper. As best seen in  FIG. 5 , each hopper  34 ,  36  has a lowermost outlet opening  50  for delivery of material to the underlying pumping assemblies  26 ,  28 , as will be explained. A common material input conduit  52  ( FIG. 2 ) allows filling of each hopper with material to be pumped. 
         [0022]      FIG. 3  depicts the pumping assemblies  26 ,  28  in perspective. Inasmuch as these assemblies are identical in structure and operation, only the assembly  26  will be described in detail, but this discussion is equally applicable to the assembly  28 . Generally speaking, the assembly  26  includes a directional valve  54 , a tubular pumping chamber  56 , and a piston assembly  58 . The valve  54  is supported on an apertured, stationary mounting block  60 , whereas the remaining components of the assembly  26  are conventionally supported by components of housing assembly  22 . 
         [0023]    The valve  54  is a four-port, three-position directional or spool valve, and includes an upright, tubular valve casing or body  62  secured to block  60 , as well as an internal spool assembly  64  within the body  62 . The body  62  includes a lower connection flange  66  supporting an upright tubular sidewall  68  and an uppermost flange  70 , thereby defining an upper material inlet end  72  and a lower output end  74 . The sidewall  68  also has a pump opening  75  between the input and output ends  72 ,  74 . 
         [0024]    The spool assembly  64  is best understood from a consideration of  FIGS. 4 and 5 . This assembly includes and upright, cylindrical, rotary spool  76  having a topmost material inlet port  78  and a lowermost tubular outlet port  80 , the latter equipped with outwardly projecting connecting lugs  82 . The spool  76  includes a first operating port  84 , a second operating port  86 , and an arcuate imperforate surface  88  between the ports  84 ,  86 . The spool  76  also has a first, smoothly arcuate internal passageway  90  extending from the inlet port  78  to first operating port  84 , and a second, smoothly arcuate internal passageway  92  extending between the outlet port  80  and second operating port  86 . 
         [0025]    The spool assembly  64  is selectively rotated by means of a drive assembly  94 . The assembly  94  includes a dished, annular drive plate  96  having locking lugs  98  designed to mate with the lugs  82 , and a sealing ring  100  between the plate  96  and the lower periphery of spool  76 . A secondary sealing ring  102  is located below the marginal edge of plate  96 . An annular bearing  104  is located within a mounting hole  106  formed in block  60  and supports a drive gear  108 . An apertured outlet plate  110 , having an upstanding tubular connector  112 , is disposed below gear  108  and supports a generally Y-shaped output tube  114 , which couples with the unit output  30 . An electric drive motor  116  depends from the plate  110  and includes a drive gear  118  located above the plate  110  and in meshed engagement with drive gear  118 . Accordingly, upon actuation of motor  116 , the spool  76  is rotated between the operational positions thereof, as will be described. 
         [0026]    The pumping chamber  56  is in the form of an elongated, tubular, laterally extending component  120 , which is secured to sidewall  68  in communication with the opening  75 . The piston assembly  58  has a material-engaging piston  122  slidably received within the component  120 , together with an elongated piston rod  124  extending rearwardly from the piston  122 . The rod  124  is housed with a tubular chamber  126 , and is coupled with a conventional drive (not shown) located within box  128 . An electric screw drive motor  130  is connected to the drive within box  128 . Actuation of the motor  130  serves to advance or retract the piston  122  within the tubular component  120 . It will also be observed that the piston  122  includes an innermost face plate  132  ( FIG. 6 ) having an arcuate, concave inboard face  134 , which is substantially frustocylindrical in shape. The face  134  is complemental with the outer surface of spool  76 , for purposes to be described. 
       Operation 
       [0027]    The operation of pumping assembly  26  will next be described, in sequential order wherein material is first withdrawn from the associated hopper  34  and introduced into the pumping chamber  56 , followed by compression of the material within the chamber  56 , and ultimate delivery of the compressed material to outlet tube  114 . Referring first to the initial step ( FIGS. 5-6 ), the spool  76  is rotated to a fill position wherein the first operating port  84  comes into registry with the pump opening  75 . The piston  122  is then withdrawn within the component  120 , as illustrated by directional arrow  136 , thereby causing material from the hopper  34  to be drawn through first passageway  90 , port  84 , and opening  75 , and then into the component  120  to create a charge of material of desired volume or weight. 
         [0028]    In the next step ( FIGS. 7-8 ), the spool  76  is rotated to a material compression position wherein the imperforate spool surface  88  comes into registry with and fully covers the pump opening  75 . The piston  122  is then advanced, as indicated by directional arrow  138 , in order to compress the charge of material between piston  122  and surface  88  to a predetermined level. This ensures that the volumetric space between the piston face and surface  88  is constant during each pump cycle, which increases pumping accuracy. 
         [0029]    In the final step ( FIGS. 9-10 ), the spool  76  is again rotated until the second operating port  86  comes into registry with opening  75 . Advancement of the piston  122  in the direction of arrow  140  serves to move the pre-compressed charge of material through the second passageway  92 , outlet port  80 , connector  112 , output tube  114 , and then through outlet  30  for downstream processing. It will be observed that, during this final step, the concave piston face  134  comes into a very close mating relationship with the outer surface of spool  76 , i.e., the clearance between the face  34  and spool  76  is on the order of a few thousandths of an inch, so that no significant amount of product remains between the piston face and spool. When the spool is next rotated in order to begin the pumping cycle, there is consequently very little tearing or smearing of the material being pumped. Furthermore, such post-discharge spool rotation is the only instance where product can be cut during the entire operation of the unit  20 . Actual testing of the present invention confirms the presence of significantly less (43%) torn ham product during pumping operations, as compared with prior equipment illustrated in U.S. Pat. No. 5,479,847. This is a decided advantage versus prior pumping assemblies. 
         [0030]    It will also be appreciated that the pumping assembly  28  operates in conjunction with the assembly  26  in a preselected relationship so that successive charges of material are delivered to the outlet  30  during operation of the pumping unit  20 . This operation may be in an asynchronous or synchronous mode, to deliver either a continuous output or successive double loads to outlet  30 . 
         [0031]    Additionally, the fact that the hoppers  34 ,  36  are mounted on carriage  38  allows the hoppers to be bodily moved in a fore-and-aft direction relative to the valves  54 . Thus, as illustrated in  FIGS. 1 and 2 , the hopper assembly  24  may be moved to the operative position thereof where the hoppers communicate with the valve spools  76  during operation of the pumping unit  20 . At the conclusion of a pumping run, the entire assembly  24  may be shifted to the position illustrated in  FIGS. 11 and 12 , in order to facilitate cleanup or repair of the pumping assemblies  26 ,  28 .