Abstract:
The present invention relates to a filling device for heterogeneous products or products which have solid or semi-solid suspended elements with variable dimensions and compactness. The valve of the invention can be used in net weight filling machines. 
     In particular, the invention relates to a filling device ( 1 ) for filling machines, comprising a hollow body ( 2 ) in which a shutter member ( 3 ) is movably fitted and acts in cooperation with a dispensing member ( 4 ), which is coaxial to said shutter member ( 3 ), to close or open a dispensing opening ( 5 ) for a product (P) to be dispensed into a container (C), characterized in that said dispensing member ( 4 ) comprises a rotatable shaft ( 10 ) comprising a screw portion ( 14 ) adapted to impart a dispensing pressure and a mixing to the product (P).

Description:
FIELD OF THE INVENTION 
       [0001]    The present invention relates to a filling device for heterogeneous products or products which have solid or semi-solid suspended elements with variable dimensions and compactness. The valve of the invention can be used in net weight filling machines. 
       BACKGROUND ART 
       [0002]    The use of weight filling systems with highly heterogeneous products or products which have solid or semi-solid suspended elements with variable dimensions and compactness is rather problematic. 
         [0003]    The known weight filling methods are all characterized by filling valves connected to a tank or a collector, and the dynamics of opening/closing the valve depend on the strategy for measuring the weight of the product dispensed. The spillage of the product from the valves is promoted by the pressure caused by the geodetic head of the product itself or by a slight pressurization (a few meters of water column at maximum) of the tank or collector which supplies the product to the valves. 
         [0004]    In addition to requiring constant mixing to avoid the stratification of the solid parts due to the difference in density, the heterogeneous products have the problem that certain pieces tend to aggregate close to the outlet of the valves, thus compromising the correct filling strategy. 
         [0005]    In order to ensure continuity to such an operation, a pressurization scheme needs to be applied to the product, which is incompatible with weight measurement systems but is typical of volumetric filling systems. This type of method is based on volumetric piston systems. These systems are physically incapable of ensuring actual filling constancy because as the physical variables of the product change, such as for example the temperature or the distribution of the suspended pieces at different densities, the dispensing at constant volume changes the weight quantity filled in the container and the resulting quantity of product actually packaged. 
         [0006]    Considering that legislation considers the weight of the packaged product as the reference declaration on the label, volumetric systems require over-filling the container in order to avoid sanctions should underweight products be introduced in the market. Thereby, more product is given to the user than what is purchased, with resulting increases in production costs. 
       SUMMARY OF THE INVENTION 
       [0007]    The problem addressed by the present invention is therefore that of providing a filling device which solves the inherent problems of the prior art devices, while allowing an accurate and efficient filling even in the case of products with high heterogeneity, i.e. comprising pieces of product having different size and consistency. 
         [0008]    Such a problem is solved by a filling device as outlined in the appended claims, the definitions of which form an integral part of the present description. 
         [0009]    Further features and advantages of the present invention will become more apparent from the description of certain embodiments thereof, given hereinbelow only by way of non-limiting, indicative example, with reference to the accompanying drawings 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0010]      FIG. 1  diagrammatically depicts a detail of a filling machine for heterogeneous products, which comprises a valve according to the invention; 
           [0011]      FIG. 2  depicts a side section view of the valve of the invention, in a first operating condition; 
           [0012]      FIG. 3  depicts the view in  FIG. 2 , in a second operating condition. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0013]    With reference to the figures, the filling device of the invention, indicated by numeral  1 , comprises a hollow body  2  in which a shutter member  3  is movably fitted and acts in cooperation with a dispensing member  4 , which is coaxial to said shutter member  3 , to close or open a dispensing opening  5  for the product P to be dispensed into a container C. 
         [0014]    The filling device  1  is inserted into a linear or rotary filling machine (not shown), in which a plurality of filling devices are operable in sequence. All filling devices  1  are operatively connected to a single motor, such as for example a synchronous motor or an asynchronous motor, by means of suitable motion transmission systems, or any filling device  1  may be operated by a dedicated motor thereof, for example a stepper motor or a brushless motor. 
         [0015]    Container C is supported by a plate  8  operatively arranged on a loading cell  9  for weighing the empty and full container C. 
         [0016]    The hollow body  2  comprises an upper portion  2   a  having a wall thickness greater than the lower portion  2   b , so as to form a shoulder  17  facing downwards at the junction point between said upper portion  2   a  and said lower portion  2   b . An inlet opening  6  for product P to be dispensed is located in the upper portion  2   a  of the hollow body  2 . The inlet opening  6  is connected to a conduit  7  which in turn is connected to a collector or tank of product P (not shown). 
         [0017]    The lower portion  2   b  ends at the bottom with a connecting portion  2   c  with which a ring nut  16  is coupled, preferably with a bayonet coupling. The ring nut  16  comprises an edge  16   a  projecting inwards, in which a sealing ring  15  is arranged. Thereby, a recess  19  having an axial extension H is created between the shoulder  17  of the hollow body  2  and the edge  16   a  of the ring nut  16 . 
         [0018]    The ring nut  16  is removable and may be replaced with a so-called “false bottle”, for example, which can be used when maintaining the device. In this case, a sanitizing fluid is indeed circulated inside the hollow body  2 , thus obtaining a perfect cleaning of all the inner parts of the device which came in contact with product P. 
         [0019]    The shutter member  3  is axially movable and comprises a hollow cylinder  18  with a median portion  18 ′ projecting outwards. The median portion  18 ′ preferably corresponds to a portion of the hollow cylinder  18  with greater wall thickness, so that the inner cavity of the hollow cylinder  18  is uniformly cylindrical. 
         [0020]    The axial extension of the median portion  18 ′ of the shutter member  3  is smaller than the axial extension H of recess  19  and the outer diameter thereof is substantially equal to, or slightly smaller than, the inner diameter of recess  19 . The median portion  18 ′ comprises a seat  20  for a gasket  21 , for example two O-rings arranged in specific notches adjacent to each other, so as to sealingly isolate an upper annular chamber  22   a  (shown in  FIG. 3 ) from a lower annular chamber  22   b  (shown in  FIG. 2 ), said chambers  22   a ,  22   b  being formed alternatively according to whether the shutter member  3  is in the raised position or in the lowered position, respectively. The shoulder  17  of the hollow body  2  and the edge  16   a  of the ring nut  16  act as abutting elements for the median portion  18 ′ of shutter  3 , thus limiting the sliding inside recess  19 . 
         [0021]    The hollow body  2  comprises an upper opening  23   a  and a lower opening  23   b  which open at recess  19 , where the upper opening  23   a  is arranged at the height of the upper annular chamber  22   a  and the lower opening  23   b  is arranged at the height of the lower annular chamber  22   b , so that when shutter  3  is in the raised position ( FIG. 2 ), the upper opening  23   a  is obstructed by the surface of the hollow cylinder  18 , while the lower opening  23   b  opens into the lower annular chamber  22   b , whereas when shutter  3  is in the lowered position ( FIG. 3 ), the lower opening  23   b  is obstructed by the surface of the hollow cylinder  18 , while the upper opening  23   a  opens into the upper annular chamber  22   a.    
         [0022]    Both the upper opening  23   a  and the lower opening  23   b  are connected to an actuating fluid source, preferably compressed air, by means of suitable pipes  24 ,  24 ′. Thereby, the actuating member  3  may be moved between the raised position and the lowered position, thus introducing the actuating fluid alternatively into the lower annular chamber  22   b  or the upper annular chamber  22   a.    
         [0023]    The hollow cylinder  18  comprises, close to the upper end thereof, a further seat  25  for a sealing ring  26 . 
         [0024]    The hollow cylinder  18  ends inferiorly with a bottom  27  in which said dispensing opening  5  opens, edged by a coupling edge  27 ′. 
         [0025]    The dispensing member  4  comprises a shaft  10  connected at the top to a pulley  11 . Pulley  11  is connected to a motor  13  by means of a transmission system  12 , such as a toothed belt, a chain or the like. As mentioned above, motor  13  may be a motor which operates all the filling devices  1  arranged on a filling machine or may be a dedicated motor thereof, exclusively dedicated to operating the filling device  1  to which it is connected. In the first case, the dispensing member  4  of all devices  1  is equipped with a brake/friction system for engaging or disengaging shaft  10  according to the predefined law of motion. The brake/friction system may be actuated by means of a suitable electric actuator or by means of a cam. The brake/friction system used is of the conventional type, for example it may be of the KEB COMBINORM-C type. 
         [0026]    Shaft  10  comprises a screw portion  14  at the bottom, in particular a single-principle screw. The outer diameter of the screw portion  14  substantially corresponds to the inner diameter of the hollow cylinder  18  so that the screw “scrapes” the inner walls of the hollow cylinder  18 . 
         [0027]    Therefore, a cavity  30  is formed above the screw portion  14 , which is always filled with product P, even when the valve is closed. 
         [0028]    The lower end of shaft  10  ends with a push rod  28  having a chamfered profile so as to cooperate with the coupling edge  27 ′ of the dispensing opening  5  to close the valve. When the shutter member  3  is in the raised position, the coupling edge  27 ′ interferes with the push rod  28 , thus closing the dispensing opening  5  of the filling device  1 , while when the shutter member  3  is in the lowered position ( FIG. 3 ), the dispensing opening  5  is open and product P may be dispensed into container C. 
         [0029]    The filling device  1  comprises a command and control unit UCC operatively connected to the loading cell  9  and to the mechanisms for actuating the dispensing member  4  (dedicated motor  13  or brake/friction system) and for introducing the actuating fluid along the conduits  24 ,  24 ′ (control unit F diagrammatically depicted in  FIG. 1 ). The unit UCC may perform at least the following functions: 
         [0030]    a) reading the tare of container C on the loading cell  9 ; 
         [0031]    b) actuating the dispensing member  4  and introducing the actuating fluid into the upper annular chamber  22   a  so as to move the shutter member downwards and open the dispensing opening  5  according to a predefined law of motion; 
         [0032]    c) detecting the weight of the container during the filling; 
         [0033]    d) upon reaching a predefined weight, stopping the dispensing member  4  and actuating the introduction of actuating fluid into the lower annular chamber  22   b  so as to move the shutter member upwards and close the dispensing opening  5  according to said predefined law of motion. 
         [0034]    The law of motion for actuating the dispensing member  4  and opening/closing the dispensing opening  5  depends on the type of product, i.e. the density thereof, the presence of larger or smaller heterogeneous pieces, etc. In certain cases, the dispensing member  4  may be actuated or stopped simultaneously as the dispensing opening  5  is opened or closed, respectively. In other cases, the actuation or stopping of the dispensing member  4  may be brought forward or delayed with respect to the opening/closing of the dispensing opening  5 . In certain cases, in particular if the density of product P is quite high, the closing of the dispensing opening  5  and/or the stopping of the dispensing member  4  may be brought forward with respect to the achievement of the predefined weight of container C, so as to take into account the electro-mechanical actuation delays and/or the time needed by the product P dispensed by the dispensing opening  5  to reach container C. 
         [0035]    The determination of the correct law of motion will be performed by conveniently adjusting the filling device case by case. 
         [0036]    The dispensing member  4  provided with screw  14  has the dual function of imparting the due dispensing pressure to product P and of providing for the continuous mixing thereof in order to make the mass of product being dispensed as homogeneous as possible. 
         [0037]    The filling device according to the invention generates a net weight filling system with the aid of volumetric systems which allow to process heterogeneous products, with the guarantee of introducing packages onto the market with the same product quantities as the weight declared on the label. This generates significant savings, thus avoiding the over-filling of the container which is instead necessary with traditional volumetric systems. 
         [0038]    It is apparent that only certain particular embodiments of the present invention have been described, to which those skilled in the art can make all those modifications required for the adaptation thereof to particular applications without however departing from the scope of protection of the present invention.