Patent Document

FIELD OF THE INVENTION 
     This invention relates to a pump for transferring and portioning pieces of meat, meat emulsions or any viscous material from a feed means such as a hopper to a packaging means. 
     BACKGROUND OF THE INVENTION 
     In the production of whole muscle meat products, such as hams, large meat chunks are transferred from a hopper to a packaging station by way of a meat pump. At the packaging station, the meat is divided into portions and stuffed into casings. 
     One type of meat pump for transferring large pieces of meat from a hopper to a packaging station is described in U.S. Pat. No. 4,060,349 to Piereder A and comprises a continuous flow, oscillating meat pump in which a single vane oscillates between a pair of walls defining a V-shaped chamber. The pump described in this patent is advantageous in the production of whole muscle meat products since it can handle large pieces of meat and causes relatively little damage to the meat chunks, in comparison with other types of pumps which use screws or gears to transport the meat. 
     However, single vane oscillating pumps have the disadvantage that the vane must stop and change direction at the end of its path, resulting in a loss of efficiency which limits the output of the pump. 
     A further disadvantage of many presently used meat pumps is that they operate at relatively low pressures. Thus, when the meat product is expelled from the pump outlet, it must be further pressurized prior to being portioned and stuffed into a casing in order to ensure that it is uniform and free of voids. The pressurization, portioning and stuffing operations are typically performed by a single apparatus which is positioned at the outlet of the meat pump. Examples of presently used portioning and packaging devices are described in U.S. Pat. Nos. 4,188,767 and 4,417,434, both to Piereder. 
     In order to improve efficiency in the production of whole muscle meat products, it would be advantageous to provide a meat pump which is provides greater output than presently used single vane oscillating meat pumps and which is able to pressurize and portion the meat product to thereby perform at least some of the operations which would otherwise be performed by a separate portioning apparatus. 
     SUMMARY OF THE INVENTION 
     The present invention overcomes the disadvantages of the prior art discussed above by providing an improved method and apparatus for continuously pumping meat chunks from a feed means to a packaging station in which the meat product is pressurized as it is being pumped and is accurately divided into portions of predetermined size at an outlet valve, thereby eliminating the need for a separate portioning device. 
     The apparatus according to the invention comprises a twin vane concentric pump in which two movable vanes are rotatable in the same direction. At least one vane is rotating at all times, and therefore losses in efficiency due to stoppage and change of direction of the vanes are substantially reduced or eliminated. 
     Pressurization of the meat product is achieved by having one vane remain stationary between the inlet and outlet while rotating the second vane toward the outlet, thereby pressurizing the meat product and expelling it through the outlet. 
     The apparatus also comprises a control system which monitors the pressure and volume within the meat pump and controls the operation of the outlet valve to ensure that the meat product is pressurized to a predetermined pressure and that the portion size is accurately controlled. 
     In one aspect, the present invention provides an apparatus for dispensing predetermined amounts of a meat product, comprising: (a) a pump housing having an inlet opening, an outlet opening and a hollow interior, with a pump axis being centrally located in said hollow interior and surrounded by a side wall of said housing; (b) first and second vane means located in said hollow interior and rotatable about said pump axis, each of said vane means having a proximal edge proximate the pump axis and a distal edge proximate the side wall of the pump, said vane means dividing said hollow interior into a pair of chambers which are substantially sealed from one another, said chambers each having a volume which varies with relative rotation of the vane means; (c) drive means for rotating said first and second vane means independently of one another; (d) valve means associated with said outlet opening for opening and closing said outlet opening; (e) pressure sensing means for sensing a pressure in at least one of said chambers; (f) volume determination means for measuring a volume in at least one of said chambers; and (g) control means for controlling rotation of said vane means and operation of said valve means in response to pressure and volume information generated by said pressure sensing means and said volume determination means. 
     In a preferred aspect of the invention, the volume determination means measures the volume of at least one of the chambers by determining the relative positions of the vane means. Preferably, the pressure sensing means senses the pressure inside the outlet chamber, and the volume determination means determines the volume of the outlet chamber. In a further preferred aspect, the apparatus further comprises a stuffing horn associated with the valve means to receive said predetermined amounts of meat product from the valve means. In yet another preferred aspect of the invention, the predetermined amounts of meat product are severed from one another by closing the valve means. In yet another preferred aspect of the invention, the vane means are connected to drive shafts driven by separate drive means. In yet another preferred aspect of the invention, the drive means comprise servo drives. In yet another preferred aspect of the invention, the drive shafts comprise a first drive shaft for driving the first vane means and a second drive shaft for driving the second vane means, the drive shafts being coaxial with the second drive shaft being hollow and having a cylindrical bore through which the first drive shaft extends. 
     In another aspect, the present invention provides a method for producing predetermined quantities of a meat product using an apparatus comprising a pump housing having an inlet opening, an outlet opening and a hollow interior, with a pump axis being centrally located in said hollow interior and surrounded by a side wall of said housing; and first and second vane means located in said hollow interior and rotatable about said pump axis, each of said vane means having a proximal edge proximate the pump axis and a distal edge proximate the side wall of the pump, said vane means dividing said hollow interior into a pair of chambers which are substantially sealed from one another, said chambers each having a volume which varies with relative rotation of the vane means; said method comprising: (a) positioning said first vane means between said inlet and outlet openings and positioning said second vane means such that a first chamber of said pair of chambers communicates only with said inlet opening and a second chamber of said pair of chambers communicates only with said outlet opening; (b) with the valve means closed, moving the second vane means while the first vane means remains stationary, the second vane means being moved by rotation about said pump axis in a direction such that the volume of the second chamber is decreased and such that a pressure within said second chamber increases to a predetermined pressure and such that the volume of the first chamber is increased and said meat product enters said inlet opening; (c) with the pressure in the second chamber at the predetermined pressure, calculating the volume of the second chamber and, where the volume is less than said predetermined amount of the meat product, proceeding to step (g) or, where the volume is greater than said predetermined amount of the meat product, proceeding to step (d); (d) opening the valve means to allow the meat product to exit the second chamber, while continuing said rotation of said second vane means to maintain said predetermined pressure; (e) closing said valve means once the predetermined amount of the meat product has been dispensed from the outlet opening; (f) repeating steps (c) to (e) until the volume measured in step (c) is less than the predetermined amount of the meat product; (g) rotating the first and second vane means in the same direction until the second vane means is positioned between said inlet and outlet openings and the first vane means is positioned such that the first chamber is in communication only with the outlet opening and the second chamber is in communication only with the inlet opening. 
     In a preferred method of the present invention, the predetermined pressure is up to about 35 bar. In yet another preferred aspect of the present invention, in which the apparatus further comprises a stuffing horn, the method further includes passing the predetermined quantities of meat product through the stuffing horn into a casing. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     Preferred embodiments of the invention will now be described, by way of example only with reference to the accompanying drawings, in which: 
     FIG. 1 is a cross-sectional side elevation view of a preferred twin vane concentric pump according to the present invention, the cross-section being in plane  1 — 1  shown in FIG. 4 which passes through the outlet opening of the pump; 
     FIG. 2 is a cross-sectional side view of the hopper and housing of the pump shown in FIG. 1, taken in plane  2 — 2  shown in FIG. 4 which passes through the pump inlet; 
     FIG. 3 illustrates the two vanes of the pump shown in FIG. 1 in isolation, and separated from one another; 
     FIG. 4 is a perspective view taken from the top and the outlet side of the housing of the pump shown in FIG. 1, with the cover removed and the position of the inlet opening being indicated in dashed lines; 
     FIGS. 5 to  9  are top plan views of the pump housing of FIG. 1 showing the positions of the vanes during various stages of operation; and 
     FIG. 10 is a flow chart illustrating the steps in the preferred method according to the present invention. 
    
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
     A preferred apparatus for transferring and portioning meat chunks is illustrated in the cross-sectional side views of FIGS. 1 and 2. The preferred apparatus includes a twin vane concentric meat pump  10  having a cylindrical housing  12  comprised of a cylindrical side wall  14 , a circular, flat bottom wall  16  and removable cover  18 . The side wall  14 , bottom wall  16  and cover  18  of the pump housing  12  together define a hollow interior space having a substantially cylindrical shape. 
     The removable cover  18  is provided with an inlet opening  20  (FIG. 2) which is in communication with a hopper  22  through which meat chunks are fed into the hollow interior of the pump  10 . The inlet opening  20  is provided proximate an edge of the cover  20 . 
     The side wall  12  of housing  14  is provided with an outlet opening  36  (FIG. 1) through which the meat product is expelled from the pump  10 . As illustrated in FIG. 2, the inlet opening  20  is spaced circumferentially from the outlet opening  36  such that the inlet opening  20  is not located directly above the outlet opening  36 , for reasons which will become apparent below. 
     Located within the hollow interior space of pump housing  12  is a cylindrical hub  24  which extends along a pump axis A. The hub  24  is comprised of two portions, a cylindrical upper portion  26  and a cylindrical lower portion  28 . The outside diameters of the upper and lower portions are preferably the same. 
     The upper portion  26  of hub  24  is mounted on a drive shaft  30  which passes through a hollow passage  32  in the lower portion  28  of hub  24 . The lower portion  28  of hub  24  is connected to a hollow drive shaft  34  through which the shaft  30  extends. Drive shafts  30  and  34  are driveable by separate driving means  31  and  35 , only schematically illustrated in FIG.  1 . Preferably, the driving means  31 ,  35  each comprise a servo drive and are contained in a gearbox. 
     Attached to the upper portion  26  of hub  24  is a first vane  38  (see FIGS. 2,  3  and  4 ) having a proximal edge  40  extending parallel to the pump axis and a distal edge  42  extending parallel to the pump axis and being proximate the side wall  14  of housing  12  so as to form a substantial seal therewith. The upper portion of the proximal edge  40  is connected to the upper portion  26  of hub  24 , while the lower portion of proximal edge  40  is closely spaced relative to the lower portion  28  of hub  24  so as to form a substantial seal therewith. The first vane  38  has a height which is substantially the same as the height of the hollow interior space of the housing  12  such that the upper edge  44  of vane  38  forms a substantial seal with the cover  18  and the lower edge  46  of vane  38  forms a substantial seal with the bottom wall  16  of the housing  12 . 
     Attached to the lower portion  28  of hub  24  is a second vane  48  (see FIGS. 1,  3  and  4 ) having a proximal edge  50 , a distal edge  52 , an upper edge  54  and a lower edge  56 . Second vane  48  has dimensions substantially identical to those of the first vane  38  to thereby form a substantial seal with the bottom wall, cover and side wall of housing  12 . The proximal edge  48  of the second vane  48  has a lower portion which is attached to the lower portion  28  of hub  24 , and an upper portion which is closely spaced relative to upper portion  26  of hub  24  so as to form a substantial seal therewith. 
     As shown in FIG. 4, the vanes  38  and  48  divide the hollow interior of housing  12  into a pair of chambers which are substantially sealed from one another. With the second vane  48  positioned between the circumferentially spaced inlet opening  20  and outlet opening  36  as shown in FIG. 4, the pair of chambers comprises an inlet chamber  58  which communicates only with the inlet opening  20  and an outlet chamber  60  which communicates only with the outlet opening  36 . As will become apparent from the discussion below, the relative volumes of the inlet and outlet chambers  58  and  60  are variable with relative rotation of the first and second vanes  38  and  48 . 
     Located externally of the housing  12  at the outlet opening  36  is an outlet valve  62  (FIG. 1) which may preferably have a valve body with a spherical or cylindrical valve chamber  70 . Inside valve chamber  70  is provided a rotatable valve element  72  having a circular cross-section as shown in FIG.  1  and having a cylindrical bore  74  through which the meat product is expelled. The valve  62  is shown in the open position in FIG. 1, and can be closed by rotating valve element by 90 degrees. As illustrated, the outlet valve is preferably in direct communication with a tubular stuffing horn  78 , such that the portioned meat product (not shown) is directly stuffed into a casing (not shown) as it leaves outlet valve  62 . 
     The apparatus  10  further comprises pressure sensing means  64  (FIG. 1) to sense the pressure within the outlet chamber  60 , and volume determination means  66  (FIG. 1) to monitor the volume of the outlet chamber  60 . Preferably, these means continuously monitor the pressure and volume inside the outlet chamber during pump operation. The pressure and volume data gathered by the pressure sensing and volume determination means are communicated to a control means  68  (FIG. 1) which controls the opening and closing of outlet valve  62  based on the supplied pressure and volume data. 
     The operation of pump  10  according to the invention will now be described below with reference to FIGS. 5 to  9 , which illustrate the positions of vanes  38  and  48  during a first cycle of pump operation. In the example described below, the maximum volume of the outlet chamber is greater than two times, and less than three times, the volume of the portioned meat product which is produced by apparatus  10 . However, it will be appreciated that the preferred apparatus  10  is capable of producing portioned meat products of a variety of predetermined sizes. Preferably, housing  12  is sufficiently large that the maximum volume of the outlet chamber  60  will be greater than the volume of the portioned meat product which is to be produced. 
     FIG. 5 illustrates the relative positions of the vanes  38  and  48  at the beginning of a first pumping cycle during operation of the pump  10 , and is essentially the same configuration described above in connection with FIG.  4 . That is, the second vane  48  is positioned between the inlet opening  20  and outlet opening  36  and the first vane  38  is positioned just ahead of the inlet opening  20 . Thus, inlet chamber  58  and outlet chamber  60  are formed, and are substantially sealed from one another by the vanes  38  and  48 . At the beginning of the cycle, the outlet valve  62  is closed, thereby preventing the pump from expelling the meat product through outlet opening  36  until it has been sufficiently pressurized. 
     During the first portion of this pump cycle, first vane  38  is rotated in the clockwise direction (toward the outlet opening  36 ) about the pump axis A, while the second vane  48  remains stationary between the inlet and outlet openings  20  and  36 . Thus, during rotation of the first vane  38 , the volume of inlet chamber  58  increases while the volume of outlet chamber  60  decreases. Therefore, a vacuum is created in the inlet chamber, allowing meat chunks to enter the inlet chamber  58  from the hopper  22 . Simultaneously, the contents of the outlet chamber  60  are pressurized. 
     As the first vane  38  is rotated toward the outlet opening  36 , with the outlet valve  62  closed, the pressure and volume inside the outlet chamber  60  are monitored by pressure sensing means  64  and volume determination means  66 . Rotation of first vane  38  continues until the meat product in the outlet chamber  60  has been pressurized to a predetermined pressure, which is preferably up to about 35 bar. FIG. 6 illustrates the relative positions of the vanes  38  and  48  at the instant that the pressure in the outlet chamber  60  reaches the predetermined pressure. If the volume of the outlet chamber  60  at this point is greater than the predetermined amount of the meat product to be expelled from the pump, the valve  62  is opened to allow the meat product to be expelled. Preferably, the meat product is directly stuffed into a casing as it is expelled from the outlet valve  62 . 
     With the outlet valve  62  open, rotation of the first vane  38  is continued in order to maintain the pressure in the outlet chamber  60  substantially equal to the predetermined pressure. 
     As the meat product is expelled from the outlet chamber  60 , the volume inside the outlet chamber  60  is monitored by volume determination means  66 . Once the volume inside the outlet chamber  60  is reduced by an amount equal to the predetermined amount, the outlet valve  62  is again closed, thereby separating the dispensed portion of meat from that remaining inside the apparatus  10 . As mentioned above, the casing is preferably stapled shut and is cut to sever the encased portion of meat from the apparatus  10 . 
     FIG. 7 illustrates the relative positions of the vanes  38  and  48  at the instant that the valve  62  is closed to sever the first portion of meat product from that remaining inside the apparatus  10 . With the pressure inside outlet chamber  60  maintained at the predetermined pressure, the volume of the outlet chamber is again determined by the volume determination means. In this example, the remaining volume of the outlet chamber  60  as shown in FIG. 7 greater than the predetermined volume of the portioned meat product, and therefore the valve  62  is again opened to expel a second portion of meat product. 
     As the meat is expelled through the valve  62 , the first vane  38  is further advanced to maintain the predetermined pressure in the outlet chamber  60 . After the predetermined amount of the meat product is expelled from the pump, the outlet valve  62  is again closed, at which point the vanes  38  and  48  have the relative positions shown in FIG.  8 . 
     Again, with the pressure within outlet chamber  60  maintained at the predetermined pressure, the volume of the outlet chamber  60  is determined. In the configuration of FIG. 8, the remaining volume of outlet chamber  60  is less than the predetermined amount of the meat product, and therefore the amount of meat product remaining in outlet chamber  60  is insufficient to produce another portioned meat product. Accordingly, at this point, both the first vane  38  and the second vane  48  are advanced in the clockwise direction until they adopt the configuration shown in FIG. 9, in which the first vane is now positioned between the inlet opening  20  and the outlet opening  36 , and in which the second vane is positioned ahead of the inlet opening  20 . The vanes are thus positioned for a second cycle of operation in which the second vane  48  is rotated clockwise while the first vane  38  is held stationary. The second cycle of operation is otherwise identical to the first cycle of operation. 
     The steps to be followed during two complete cycles of pump operation are shown in the flow chart of FIG.  10 . 
     In the above-described example, the operation of the pump  10  was described after initial pump start-up, in which the outlet chamber  60  is full of meat chunks at the start of each cycle. It will be appreciated that, upon initial start-up of the pump  10 , the outlet chamber  60  will be empty, and therefore the outlet valve  62  is not opened during the first cycle of operation. 
     During pump operation, the first and second cycles are repeated in the manner described above to continuously expel predetermined volumes of the meat product from the pump  10 . The pressurization of the outlet chamber  60  with the valve closed permits effective pressurization of the meat product therein, thereby eliminating the need for further pressurization of the meat product after it is expelled from the pump. 
     Furthermore, rotation of both vanes  38  and  48  in the same direction, in combination with simultaneous rotation of the vanes  38  and  48  by independent driving means at the end of each cycle, improves pump efficiency by avoiding loss of momentum due to stopping and changing the direction of rotation at the end of each cycle. 
     In addition, the use of pressure and volume sensing means, and the use of a control means to control operation of the outlet valve, permits the production of accurately controlled portions of the meat product which eliminates the need for a separate portioning apparatus. 
     Although the invention has been described in connection with certain preferred embodiments, it is not intended to be limited thereto. Rather, the invention includes all embodiments which may fall within the scope of the following claims.

Technology Category: a