Abstract:
The invention relates to a single seed dispenser ( 10 ) for a precision automatic sower comprising a cover ( 11 ) for seeds to be distributed joined to a body ( 12 ) containing a cavity ( 24 ) in communication with an aspirator of the seeds via a conduit ( 22 ) inserted in a hole ( 23 ) realised on the body ( 12 ), a distribution disc ( 13 ) with holes ( 38, 54 ) contained in a compartment delimited by said body ( 12 ) and by said cover ( 11 ); a driving disc ( 31 ) joined through pins ( 53 ) to the distribution disc ( 13 ), both discs being put into rotation by means of a shaft ( 29 ) actuated by an actuator for commanding rotation of the discs ( 13, 31 ); and a selector device ( 14 ) for the seeds pivoted on the edge of the body ( 12 ), where the selector device ( 14 ) comprises a plate ( 142 ) which presents, on a side facing the centre of the distribution disc ( 13 ), at least two toothed portions ( 143, 144 ), having teeth of different sizes and a curved sector ( 59 ) mounted against the surface of the distribution disc ( 13 ) opposite to the plate ( 142 ) and is provided with protrusions ( 591 ) having inclined surface ( 592 ) facing the distribution disc ( 13 ) at holes ( 38 ) therein.

Description:
TECHNICAL FIELD 
       [0001]    The present invention relates to a precision automatic sowing machines, in particular of a pneumatic type, able to sow various vegetable species by distributing single seeds on the ground at regular intervals along a seeding line. In particular, the present invention relates to the seed dispenser with which sowing machines are equipped. 
       PRIOR ART 
       [0002]    Precision sowing machines have various advantages with respect to machines of the universal type; in fact the use thereof eliminates the need for thinning-out the plants at the moment of budding, enables reducing operations of cultivation and reduces waste of seeds. Precision sowing machines are substantially divided into two categories on the basis of the system used for distribution: mechanical sowers and pneumatic sowers. 
         [0003]    Numerous patents and patent applications relating to sowers are known. In particular, among the documents relating to pneumatic sowing machines, French patent application FR2678472 describes a machine which distributes seeds due to the action of two rotating discs mounted on and set in action by respective tubes arranged concentrically of one another. 
         [0004]    A plurality of holes is fashioned on each disc, arranged parallel to the external edge along circumferences of different dimensions. The seeds, singularly engaged in the holes of the rotating disc by an air current generated by a pneumatic pump, are accompanied up to the point of expulsion. 
         [0005]    UK patent GB 1 162 683 described a sowing machine provided with rotating and stationary distribution elements; grooves are present on the rotating distribution means which grooves extend radially for accompanying the seeds to the point of expulsion. The machine further comprises a blower or an aspirator for generating an air flow which adds adhesion of the seeds to the rotating distribution element. 
         [0006]    Document EP 0 636 305 also illustrates a precision pneumatic sowing machine comprising a device provided with a pair of rotating perforated discs. 
         [0007]    A first disc exhibits, on a first face thereof, a hooking point for a connecting shaft to an actuator and on a periphery of a second face a plurality of fixed pins projecting in an opposite direction to the direction of the connecting shaft of the actuator. 
         [0008]    A second disc is characterised by a flat surface on a circular crown of which a plurality of series of holes is present, a first series being able to engage the seeds and a second series being able to engage the fixed pins on the first disc. 
         [0009]    The fixed pins, apart from transferring the motion induced by the actuator on the first disc to the second disc, being projecting, also serve to shake the seeds which, by gravity, are deposited on the bottom of the body of the sowing machine, so that they can be brought in proximity of the holes of the second disc where they are captured by the air circulation created by a pump. A comb, installed so as to superpose on the circular crown of the second disc, has a toothing realised so as to cause the seeds to fall if positioned incorrectly in or in proximity of the holes of the second disc. The seeds falling on the bottom of the body are newly shaken by the pins so that they can newly engage in proximity of the holes. 
         [0010]    The mechanisms for collecting the single seeds used by these machines, whether perforated cylinders or holed discs, are subject to possible malfunctioning caused by seeds which engage stably in the holes of the rotating surfaces. 
         [0011]    In fact, each sowing machine can be used for sowing various types of seed, characterised by various dimensions and shapes, for example, substantially spherical or elongate, with a regular surface of roughness of various breadths and/or depths. In particular, seeds of particularly small dimensions with respect to the average of their species, or elongate, can get jammed in the holes or, indeed, can cross the separator elements, i.e. discs and cylinders, and can even jam the aspirating motor. 
         [0012]    Not only, in the case of seeds having an irregular or elongate shape it is possible that, because of the shape, the seeds, while having dimensions within the norm for the vegetable variety thereof, remain stuck in the holes, making the holes unusable. 
         [0013]    When these conditions occur the efficiency of the process is reduced, creating empty spaces along the sowing line, and in the most complicated cases the machine has to be shut down to be cleaned. 
         [0014]    Further, the machine operator is not always able to detect that seeds have not been sown along the line. If the point where the sowing procedure has not been successful is rapidly identified, the sowing can be repeated in that place, but with a consequent increase in costs and with a waste of time. Otherwise, if the lack of sowing is not identified, there will be empty spaces and losses in production. 
         [0015]    To reduce the occurrence of these drawbacks mainly two solutions have been adopted; the first involves the possibility of replacing the discs and time-by-time mounting the discs with holes that are appropriate for the seeds being sown. The second solution involves the installation of further devices, for example as described in patent EP 0 636 305, such as rings having filter holes or grids. 
         [0016]    The first solution necessarily requires the machine to be shut down for replacement or cleaning of the surfaces on which the holes have been clogged by jammed seeds having irregular shapes or sizes that are out of the norm. 
         [0017]    The second solution is an improvement on the first, and reduces the number of various discs with different hole sections, though there remains the likelihood of machine shut-downs due to the blocking of the holes in the case of seeds having irregular shape. 
       SUMMARY OF THE INVENTION 
       [0018]    The present invention constitutes an improvement with respect to the machine described in patent EP 0 636 305 and the main aim is to realise an improved pneumatic sowing machine able to obviate the specific problem of seeds jammed in the machine discs, thus eliminating the irregularity in the distribution of the seeds and the need to shut the machine down for cleaning the apparatus during the course of the sowing operations. 
         [0019]    The main characteristic of the present invention, as specified in claim  1 , consists in providing a mechanism that can disengage the seeds from the holes of the disc combined with an element that improves the ordering of the seeds so that they can engage on the rotating distribution disc so that the seeds are accompanied up to the point of expulsion. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0020]    The technical characteristics of the invention will more clearly emerge from the description that follows, by way of non-limiting example, with reference to the accompanying figures which represent one of the possible embodiments in which: 
           [0021]      FIG. 1  is a perspective view of the distribution group for a sowing group according to an embodiment of the invention; 
           [0022]      FIG. 2  is an internal detail of a distribution group for a sowing machine of figure from which the body of the seeds has been removed; 
           [0023]      FIG. 3  is a perspective exploded view of the sowing machine of  FIG. 1  and some details in larger scale of the driving disc; 
           [0024]      FIG. 4  is a section view according to line IV-IV of  FIG. 2 ; 
           [0025]      FIGS. 5A, 5B  show details of the sowing machine of  FIG. 1  in two steps of the releasing of a seed. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0026]    The distributor  10  of seeds of the invention, shown in  FIG. 1 , can be mounted on any known sowing machine, not represented, and is substantially formed by a body  12  made of plastic and a cover  11  which form a compartment internally of which a distribution disc  13  is housed ( FIG. 2 ). A selector device  14  is fixed on the body  12  so as to be partially superposed on the surface of the distribution disc  13 . 
         [0027]    The cover  11  is provided with a hopper  15  for loading the seeds, and in the upper part and lower part thereof, with a hollow protrusion able to form, with a like part of the body  12  a discharge conduit  15 . Further, it exhibits a perforated flange  18  on the perimeter thereof. 
         [0028]    A support  161  is installed at a free end of the discharge conduit  16  for a photocell (not illustrated) able to detect passage of the seeds; the photocell is positioned, by means of the support  161 , in a point such as not to interfere with the passage of the seeds and is electrically connected to a warning device or to a control device programmed so as to carry out the necessary actions. 
         [0029]    These warning and control devices are made according to the prior art and are not shown in the figures. 
         [0030]    The body  12  contains an aspirating cavity  24  ( FIG. 3 ) on a wall of which a hole  23  is present in which a conduit  22  is fitted, which connects the cavity  24  to an air aspirating device, of known type and not illustrated. 
         [0031]    The body  12  exhibits, on an edge thereof, a flange  19  characterised by dimensions such as to be coupled to the perforated flange  18  of the cover  11 . 
         [0032]    A first knurled end of locking pins  181  ( FIG. 3 , detail A) is fixed, for example on the flange  19 , destined to engage with a second end thereof in the holes made on the flange  18 . 
         [0033]    Further, a groove  182  is made at the second end of each of the locking pins  181 , contained in a perpendicular plane to the longitudinal axis of the pin. 
         [0034]    When the body  12  is flanked to the cover  11  so as to form a closed space, the blocking pins  181  cross the holes of the flange  18 , projecting with the free end thereof from the cover  11 . 
         [0035]    One or more springs  191  engage in the grooves  182  of the projecting ends of the pins  181 , acting as holding elements to stabilise the position of the body  12  and the cover  11  ( FIG. 1 ). 
         [0036]    Alternatively, the body  12  and the cover  11  can be joined to one another with other known means, such as, purely by way of example, screws closed by bolts or profiled plates which engage in seatings therefor. 
         [0037]    Further, in order to guarantee the air seal of the distributor  10  between the two flanges  18 ,  19 , a seal is interposed  51  ( FIG. 3 ) formed, differently to the prior art, in one or two pieces joined so as to form a single plane for improving the seal, simplifying the construction thereof and reducing friction. The distribution disc  13  closes the open side of the aspirating cavity  24  of the body  12  and at least two series of holes  38 ,  54  are realised on the edge of the disc  13 , arranged on concentric circumferences. 
         [0038]    A hole  27  is included internally of the body  12 , in which a shaft  29  is fitted, supported by a bearing-spacer-oil seal group  28  ( FIG. 4 ). The shaft  29  is set in rotation by an actuator, for example by means of a gearing mounted on a first free end (not shown). The other end of the shaft  29  is fixed to a driving disc  31  located in the aspirating cavity  24  internally of the closed volume by the distribution disc  13 . 
         [0039]    At least a curved element  40  is included so as to be mounted in a corresponding seating  42  made on the body  12 . The element  40  has a curvature having a greater radius than the driving disc  31  and the edge thereof preferably follows a circumference which intersects the first series of holes  38  for aspirating the air made on the distribution disc  13 . The element  40  can be made of a plastic or metal plate and is arranged perpendicularly to the surface of the distribution disc  13 . The element  40  can be replaced by a plate provided with holes, located parallel to a surface of the distribution disc  13  or, alternatively, by a net having suitably calibrated meshes. 
         [0040]    The use of separator elements, such as the curved element  40 , mounted transversally to the holes  38  of the distribution disc  13 , is effective in preventing the passage into the holes of elongate seeds or seeds having a small section, at least up to a certain range of dimensions with respect to the diameter of the holes  38 . 
         [0041]    This solution enables reducing the number of interchangeable discs, differentiated by the dimensions of the holes made on them, necessary for adapting the sowing machine to the great variety of the seeds to be sown. 
         [0042]    The distribution disc  13  is set in rotation by the driving disc  31  which transmits the rotation induced thereon by the shaft  29 . In fact, pins  53  are fixed on the edges of the driving disc  31 , on the face turned towards the distribution disc  13  and opposite the face in which the shaft  29  projects, which pins  53  engage in the second series of holes  54  made on the distribution disc  13  along a circumference, preferably having a smaller radius than the radius on which the holes  38  are made. 
         [0043]    The height of the pins  53  is such that they project from the surface of the distribution disc  13  so as to obtain a triple result; first, by transferring to the distribution disc  13  the motion induced by actuator on the driving disc  31 , second, by keeping in position a continuous seal  57  which seals the contact edge between the driving disc  31  and the distribution disc  13 , and third, by shaking the seeds which by force of gravity tend to deposit on the bottom of the cover  11 . In fact, following the shaking induced by the pins  53 , the seeds are moved upwards and when they fall back a part of them is sucked in proximity of the holes  38 . 
         [0044]    As mentioned in the foregoing, a selector device  14  is installed such as to superpose at least partially on a more external part of the distribution disc  13 . The body of the selector device  14  can be realised as a single piece or alternatively can be assembled from several elements appropriately joined to one another. In the embodiment illustrated in  FIGS. 2 and 3 , two parts can be identified, a first elongate part, or arm  141 , a first end of which has a hole in which one of the pins  181  fixed on the flange  19  of the cover  12  is engaged. A plate  142  is fixed on a second end of the arm  141 , the edge of which facing the shaft  29  exhibits a toothing made up by two toothed portions  143 ,  144 . A spring  145  is mounted on the plate  142  on the opposite side to the distribution disc  13  which, by forcing on the cover  11  pushes on the plate  142  to keep it in adherence to the surface of the distribution disc  13 , thus preventing the seeds from being able to insert between them. 
         [0045]    A mechanism is installed externally of the body  12 , actuable by an operator charged with the management of the means, for regulating the relative position of the selector device  14  with respect to the distribution disc  13 . The mechanism comprises an eccentric pin  26  of the selector device commanded by a manual regulating arm  25  having an indicator for reading the inclination of the selector device  14 . 
         [0046]    Activating the regulating arm  25  causes the eccentric pin  26  to rotate, modifying the position of the selector device  14  with respect to the position of the holes  38  as a function of the type of seeds to be distributed. 
         [0047]    The displacing and regulating of the position of the selector device  14  can also be done using other mechanical elements, such as for example screws, levers, cursors in order to obtain the same effect. 
         [0048]    The toothing is made with at least a first and a second toothed portion  143 ,  144  so that a single seed is engaged on the holes  38 , so as to attain the objective of the distributor  10  of depositing a single seed at a time on the ground. In fact, the aspirating effect can be such that a plurality of seeds halt in proximity of a same hole and this fact would lead to several seeds being deposited in a single place. 
         [0049]    The first portion  143  of the toothing performs a first selection step, distancing the aspirated seeds in a less stable way. The second portion  144 , characterised by teeth of a greater height with respect to the first, is able to apply a more vigorous push so as to detach any seeds in excess still attached in proximity of the holes  38 . During and due to the rotation, the seeds not finding a free place to settle in the holes  38  or which have been distanced from the selector device  14  fall onto the bottom of the cover  11  so that they can be recycled. 
         [0050]    Further, the aspirating cavity  24  contains an air deviator  58  located in the area close to the discharge conduit  16  so as to interrupt the aspirated air flow which enables the seeds to remain adhering to the distribution disc  13 . Following the interruption of the air flow, the force maintaining the seeds against the distribution disc  13  ceases, and the seeds can fall towards the mouth of the discharge conduit  16 . 
         [0051]    As illustrated in  FIG. 3 , the surface of the air deviator  58  occupies only a part of the breadth of the internal circumference of the aspirating cavity. 
         [0052]    Again inside the aspirating cavity  24 , a curved sector  59  is installed, made of plastic or metal, which extends along a circumference for a breadth that is substantially complementary to the circumference of the air deviator  58 . Protrusions  591  are present on a vertical surface of the sector  59 , for example on the surface facing towards the outside of the distributor ( FIG. 3 ), which protrusions  591  ( FIG. 3 , detail B) are located at determined intervals. 
         [0053]    The radius of the circumference along which the sector  59  is installed is such that the position of a free end of the protrusions  591  coincides with the holes  38  made on the distribution disc  13 . 
         [0054]    The protrusions preferably have a rectangular section and terminate on the side facing towards the distribution disc  13  with a substantially chisel-shaped end exhibiting an inclined surface  592 . The height of the protrusions  591  is such that the end of the inclined surface  592  brushes the surface of the distribution disc  13  so as to apply a thrust able to dislodge the seeds to the ends of the clogged seeds which project through the holes  38 . 
         [0055]    In the operating step, after having loaded the seeds in the cover  11 , the distribution disc  13  is set in rotation (in a clockwise direction in  FIG. 2 ) and the air aspirating device is activated. The aspiration of the air through conduit  22 , the hole  23 , the aspirating cavity  24  and the holes  38  is such that the seeds shaken by the pins  53  are retained on the disc in proximity of the holes  38  and set in rotation. When the seeds drawn by the distribution disc  13  pass through the toothed portion  143  of the selector device  14 , the excess seeds are progressively removed from the disc  13 , and if the selector device  14  is regulated adequately a single seed will be retained for each hole  38 . The seeds will be retained on the distribution disc  13  up to when the respective hole reaches the discharge position, contiguous to the conduit  16  downstream of the aspirating cavity  24  where the seeds are no longer retained by the aspirating effect due to the presence of the air deviator  58 . 
         [0056]    During regular functioning of the machine, it can happen that seeds of a particular shape engage so as to remain blocked in the respective hole  38  ( FIG. 5A ) notwithstanding the fact that the aspirating action is interrupted due to the presence of the air deviator  58 . This drawback reduces the inefficiency of the working due to the drawbacks indicated in the foregoing. 
         [0057]    When this condition occurs the machines of the invention, differently from those of the prior art, are able to disengage the seeds blocked in the holes  38 . The part of the seed trapped on the distribution disc  13  projects, through one of the holes  38 , in the direction of the protrusions  591 , as mentioned in the foregoing, brush, with the inclined plane  592  thereof, the surface of the distribution disc  13 . As shown in  FIG. 5B , due to the rotation of the distribution disc  13  the projecting part of a trapped seed goes into contact with the chisel-shaped surface  592  of one of the protrusions  591 , receiving a push which causes the seed to exit from the hole. Further, the presence of the photocell detects the correct passage of the seeds. If the above is not true, a warning signal is emitted to advise the operator of an unexpected functioning, caused for example by the last of the seeds loaded in the hopper having passed through, or by the blocking of an internal organ which interrupts the flow of seeds. The ready signalling reduces the impact of further cycles for non-seeded areas or lost production. 
         [0058]    It is clear from the preceding description that the invention attains the fixed objective of improving the efficiency of the distribution of single seeds. Thanks to the combined action of the protrusions  591  fixed on the sector  59  and the selector device  14  which regulate the number of seeds stopped by the air pressure created by the aspirator in proximity of the holes  38  on the distribution disc  13 . 
         [0059]    The design of the selector device  14 , with respect to that of the like organs described in the prior art, enables simpler and easier operations for replacing the distribution discs. 
         [0060]    Naturally the present invention is susceptible to numerous modifications or variants without forsaking the scope of protection, as defined by the appended claims. 
         [0061]    Further, the materials and the equipment used for realising the present invention, as well as the forms and dimensions of the single components, can be the most suitable according to specific needs.