Abstract:
A multi-blade dosing valve comprising the following elements:
   a valve body provided with a central opening;   a plurality of shafts, each provided with a respective blade, which extend transversely to the central opening; the blades being able to close, at least partially, the central opening;   a motor unit which causes the opening/closing of the blades; and   vibrators to set in vibration the shafts and the blades. The multi-blade dosing valve comprises an independent vibrator for each shaft.

Description:
[0001]    The present invention relates to a multi-blade dosing valve. 
         [0002]    The invention relates more particularly, but not exclusively, to a multi-blade dosing valve to be used in an apparatus for the periodic discharge of a granular or pulverulent material from a storage tank, for example a silo. 
       BACKGROUND OF THE INVENTION 
       [0003]    Multi-blade dosing valves, like the one described for example in U.S. Pat. No. 3,784,061, are already known. 
         [0004]    The multi-blade dosing valve described in U.S. Pat. No. 3,784,061 comprises the following elements:
   a valve body provided with a central opening crossed, in actual use, by the pulverulent or granular material, which is discharged from a hopper into a distribution duct;   a plurality of shafts, each provided with a respective blade which extends transversely to said central opening;   a motor unit, which, by rotating the plurality of shafts, causes the opening/closing of said blades to adjust the amount of material discharged from the hopper; and   a vibrator device, which can set in vibration both said valve body and said shafts provided with blades.   
 
         [0009]    One of the main drawbacks of such a multi-blade dosing valve is that the energy of the vibrator device is dispersed in the valve body and does not conveniently reach the blades. This involves the formation of bridges of pulverulent material in the gaps between the blades and a lower efficiency and precision in the dosage of the material. 
         [0010]    Furthermore, setting in vibration the entire valve body implies a remarkable noise level of the apparatus, with a consequent acoustic pollution of the work environment. 
       SUMMARY OF THE INVENTION 
       [0011]    Therefore, the main object of the present invention is to provide a multi-blade dosing valve which is free from the aforesaid drawbacks and, at the same time, is simple and economical to produce. 
         [0012]    Therefore, the present invention provides a multi-blade dosing valve according to claim  1 , and preferably, any one of the claims directly or indirectly depending on claim  1 . 
         [0013]    First object of the present invention is a multi-blade dosing valve comprising the following elements:
   a valve body provided with a central opening;   a plurality of shafts, each provided with a respective blade which extend transversely to the central opening; the blades being able to close, at least partially, the central opening;   a motor unit which causes the opening/closing of the blades; and   vibrators to set in vibration shafts and blades;   
 
         [0018]    the multi-blade dosing valve being characterized in that it comprises an independent vibrator for each shaft. 
         [0019]    In addition, the multi-blade dosing valve is provided with a vibration damping bushing on each shaft. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0020]    For a better understanding of the present invention, it will be now described a preferred embodiment, purely as a non-limiting example and with reference to the accompanying drawings, wherein: 
           [0021]      FIG. 1  shows an axonometric view of a first closed configuration of a multi-blade dosing valve according to the teaching of the present invention; 
           [0022]      FIG. 2  shows a plan of the multi-blade dosing valve in its first closed configuration of  FIG. 1 ; 
           [0023]      FIG. 3  shows a side view of the multi-blade dosing valve in its first closed configuration of  FIG. 1 ; 
           [0024]      FIG. 4  shows a cross section A-A on the plan of  FIG. 2 ; 
           [0025]      FIG. 5  shows an axonometric view of a second open configuration of a multi-blade dosing valve according to the teaching of the present invention; 
           [0026]      FIG. 6  shows a plan of the multi-blade dosing valve in its second open configuration of  FIG. 5 ; 
           [0027]      FIG. 7  shows a side view of the multi-blade dosing valve in its second open configuration of  FIG. 1 ; 
           [0028]      FIG. 8  shows a cross section A-A on the plan of  FIG. 6 ; and 
           [0029]      FIG. 9  (with an enlarged element) illustrates a portion of the multi-blade dosing valve according to the invention. 
       
    
    
       [0030]    In the attached figures,  10  indicates, as a whole, a multi-blade dosing valve according to the teaching of the present invention. 
       DETAILED DESCRIPTION OF THE INVENTION 
       [0031]    The dosing valve  10  comprises a substantially square valve body  20  provided with a substantially square central opening  30  crossed, in actual use, by the pulverulent or granular material which is discharged from a hopper (not shown) into a distribution duct (not shown). 
         [0032]    As shown in greater detail in  FIG. 4 , the valve body  20  can consist of substantially equal upper half-shell  20 A and lower half-shell  20 B. 
         [0033]    With regard, for example, to the upper half-shell  20 A (but the same can be said for the other half-shell  20 B), it comprises a relative truncated pyramidal part  40 A which is connected to a respective flange  50 A, which looks like a horizontal frame of the truncated pyramidal part  40 A. In the upper half-shell  20 A, the truncated pyramidal part  40 A protrudes downwards so that the truncated pyramidal part  40 A decreases from the top downwards. 
         [0034]    In the preferred embodiment shown in the attached Figures, nr. 6 openings  70 A (3 for each edge) are formed on two opposite and parallel edges  60 A,  60 B of the truncated pyramidal part  40 A. The perimeter of each opening  70 A is formed by a broken line comprising three sides. 
         [0035]    Similarly, in the lower valve  20 B, the truncated pyramidal part  40 B protrudes upwards so that the truncated pyramidal part  40 B decreases from the bottom upwards. 
         [0036]    Analogously to the upper half-shell  20 A, nr. 6 openings  70 B (3 for each edge) are formed on two opposite and parallel edges  65 A,  65 B of the truncated pyramidal part  40 B. The perimeter of each opening  70 B is formed by a broken line comprising three sides for reasons that will be explained later. 
         [0037]    In actual use, the smaller bases of the truncated pyramidal parts  40 A,  40 B are pressed on each other. 
         [0038]    Since, as already stated, the two truncated pyramidal parts  40 A,  40 B are identical, each opening  70 A belonging to the truncated pyramidal part  40 A coincides with a corresponding opening  70 B of the truncated pyramidal part  40 B. Each pair of openings  40 A,  40 B constitutes a hexagonal seat  80  housing a relative hexagonal bushing  90  shown in more detail in  FIG. 9  and in the relative magnification. 
         [0039]    For the person skilled in the art it is obvious that the hexagonal seat  80  is equivalent to any seat having any polygonal shape able to prevent a rotation of the bushing. 
         [0040]    Moreover, at least in part, the polygon sides can be curved, and not rectilinear. 
         [0041]    As shown in  FIG. 9 , the hexagonal bushing  90 , made preferably, but not exclusively, of polyurethane, has six peripheral sides  90 A, each of which is provided with a corresponding discharge notch  90 B. In the hexagonal bushing  90  it is further provided a circular central through hole  90 C to house a respective shaft  100 A,  100 B,  100 C on which a respective blade  110 A,  110 B,  110 C ( FIGS. 1, 2, 5, 7 ) is mounted. 
         [0042]    Thanks to known and not shown systems, each shaft  100 A,  100 B,  100 C is set in rotation around a respective longitudinal axis (X 1 ), (X 2 ), (X 3 ) by means of a single motor unit  200  which transmits the motion to a rack, or to a system of levers. The rotation of the shafts  100 A,  100 B,  100 C also rotates the blades  110 A,  110 B,  110 C, thus allowing to pass from the closed configuration of  FIG. 1  to the (at least partially) open configuration shown in  FIG. 5 . 
         [0043]    Obviously, the degree of opening of the blades  110 A,  110 B,  110 C depends on the angle of rotation of each shaft  100 A,  100 B,  100 C around its own axis (X). 
         [0044]    Each degree of opening of each blade  110 A,  110 B,  110 C may be equal to or different from the one of the other two blades. This is because each blade  110 A,  110 B,  110 C may also have a rotation system independent of the rotation systems of the other two blades. 
         [0045]    As shown in more detail in  FIGS. 3, 7 , a respective arm  115 A,  115 B,  115 C (having a respective longitudinal axis (Y 1 ), (Y 2 ), (Y 3 )) which extends perpendicularly to the axis (X 1 ), (X 2 ), (X 3 ) protrudes from each shaft  100 A,  100 B,  100 C. 
         [0046]    One of the characteristics of the present invention is that a respective vibrator  250 A,  250 B,  250 C is mounted on each arm  115 A,  115 B,  115 C. 
         [0047]    Furthermore, each hexagonal bushing  90  is a damping device designed to avoid, insofar as possible, the transmission of the vibrations generated by the vibrators  250 A,  250 B,  250 C also to the valve body  20 . 
         [0048]    Thanks to this arrangement, most of the vibration energy is conveyed towards the organs which mostly need it, namely the shafts  100 A,  100 B,  100 C and the respective blades  110 A,  110 B,  110 C, avoiding, insofar as possible, a dissipation of the vibration energy on the valve body  20 . 
         [0049]    In a further embodiment of the present invention, not shown, the blades are asymmetrical relative to the respective axis (X 1 ), (X 2 ), (X 3 ), rather than symmetrical, as shown in the embodiment in the attached  FIGS. 1-9 . 
         [0050]    In another embodiment, not shown, the blades can have respectively different initial inclinations. 
         [0051]    Each vibrator  250 A,  250 B,  250 C is independent from the other two, and therefore it can be programmed to vibrate (or not to vibrate at all) with frequencies and intensities possibly different from those of the other shafts  100 A,  100 B,  100 C and blades  110 A,  110 B,  110 C. This means that thanks to the teaching of the present invention it is possible to adjust and program the vibration characteristics of each shaft  100 A,  100 B,  100 C (and thus of each blade  110 A,  110 B,  110 C) depending on the discharge parameters of the pulverulent (or granular) product from the hopper. 
         [0052]    For example, the performance of the dosing valve can be possibly optimized by increasing the frequency of the external vibrators  250 A,  250 C with respect to the one of the central vibrator  250 B ( FIG. 3 ). 
         [0053]    Although the attached figures show embodiments wherein each vibrator  250 A,  250 B,  250 C is mounted on a respective arm  115 A,  115 B,  115 C, it is possible to imagine an embodiment (not shown) wherein each vibrator  250 A,  250 B,  250 C is mounted on the respective shaft  100 A,  100 B,  100 C, directly or through a suitable bushing (not shown) fitted on the shaft  100 A,  100 B,  100 C. 
         [0054]    Furthermore, although in the attached figures the axes (X 1 ), (X 2 ), (X 3 ); (Y 1 ), (Y 2 ), (Y 3 ); (Z 1 ), (Z 2 ), (Z 3 ) are all mutually perpendicular, in other embodiments not shown these axes (X 1 ), (X 2 ), (X 3 ); (Y 1 ), (Y 2 ), (Y 3 ); (Z 1 ), (Z 2 ), (Z 3 ) are mutually inclined at angles suitably selected by the user according to the wished vibrating effect on each shaft  100 A,  100 B,  100 C. 
         [0055]    Such respective inclinations can be suitably chosen on any plane that contains at the same time a pair of axes (X 1 ), (X 2 ), (X 3 ); (Y 1 ), (Y 2 ), (Y 3 ); (Z 1 ), (Z 2 ), (Z 3 ). 
         [0056]    In other words, in an embodiment not shown, each axis (Z 1 ), (Z 2 ), (Z 3 ) of each vibrator  250 A,  250 B,  250 C may be inclined with respect to the corresponding axis (Y 1 ), (Y 2 ), (Y 3 ) at a suitable angle on any plane (not shown) that contains at the same time the pairs of axes (Y 1 ), (Z 1 ); (Y 2 ), (Z 2 ); (Y 3 ), (Z 3 ). 
         [0057]    The angles of inclination between the pairs may be equal or different. 
         [0058]    At most, at least one angle between the pairs of axes (X 1 ), (X 2 ), (X 3 ); (Y 1 ), (Y 2 ), (Y 3 ); (Z 1 ), (Z 2 ), (Z 3 ) may be equal to zero. 
         [0059]    In this case, the axis (Z 1 ), (Z 2 ), (Z 3 ) of the vibrator  250 A,  250 B,  250 C coincides with the axis (Y 1 ), (Y 2 ), (Y 3 ) of the respective arm  115 A,  115 B,  115 C, or coincides with the axis (Y 1 ), (Y 2 ), (Y 3 ) of the respective shaft  100 A,  100 B,  100 C. 
         [0060]    The same comments also apply when each vibrator  250 A,  250 B,  250 C is mounted on the respective shaft  100 A,  100 B,  100 C. 
         [0061]    In this latter case, then, the relevant elements are the pairs of axes (X 1 ), (Z 1 ); (X 2 ), (Z 2 ); (X 3 ), (Z 3 ), since the arms  115 A,  115 B,  115 C no longer exist. 
         [0062]    The dosing valve of the invention can also be provided with known and not shown means which allow the buyer to finely adjust the angles of inclination between the different axes (X 1 ), (X 2 ), (X 3 ); (Y 1 ), (Y 2 ), (Y 3 ); (Z 1 ), (Z 2 ), (Z 3 ) in order to adjust, from time to time, the dosing valve to the chemical/physical characteristics of the material to be discharged through the valve. 
         [0063]    The main advantages of the aforesaid multi-blade dosing valve consist in preventing the formation of bridges of material and in drastically reducing its noise level. 
         [0064]    In addition, it allows a more precise dosage of the amount of material coming out of the valve with a reduced dissipation of energy that, thanks to the presence of the damping means, is used to set in vibration the parts of the dosing valve (shafts and blades) necessary to induce the descent of the material, thus avoiding to dissipate energy to set in vibration the valve body.