Abstract:
A device for calibrating the product dispensed by a distributor ( 5 ) of granular materials comprises a calibration aperture ( 9 ) formed in a through-conduit ( 8 ) for the granular material between the distributor ( 5 ) of the seed and a device ( 4 ) for transporting the material, and a gate ( 10 ) associated with the calibration aperture ( 9 ) and movable between a calibration position, in which the aperture ( 9 ) is open and the material from the distributor ( 5 ) is conducted via the aperture ( 9 ), and a distribution position, in which the aperture ( 9 ) is closed and the material is conducted therebeyond along the through-conduit ( 8 ), wherein a motorized actuator ( 11 ) is connected to the gate ( 10 ) so as to make the gate ( 10 ) movable between those positions.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This application is a U.S. National Stage Application of PCT/IB2012/051399 filed on Mar. 23, 2012, which claims priority to Italian patent application PD2011A000093 filed on Mar. 25, 2011, the contents of both of which are incorporated herein by reference. 
     FIELD 
     The present invention relates to a device for calibrating the product dispensed by a granular material distributor, particularly intended for calibrating and consequently regulating the quantity of granular material, such as seeds, fertilizers or the like, dispensed by the distributor of a pneumatic agricultural seed-drill. 
     BACKGROUND 
     In agricultural seed-drills with pneumatic distribution, there are conventionally used rotating distributors having blades which can be regulated in order to vary the quantity of material dispensed per unit of surface-area both via changes of speed and by means of volumetric variation of the bladed members of the distributor. The regulation brought about must be controlled by means of a so-called calibration operation before starting the distribution in the field so as to ascertain that the quantity of material effectively distributed per unit of surface-area corresponds to the desired expectations. 
     For that reason along the through-conduit for the material dispensed by the distributor towards the pneumatic transport device of the material, there is provided the possibility of varying the flow of the material being moved towards a collection container so as to be able to put into operation manually, in a simulated manner, the distributor and to weigh the material dispensed in that manner. 
     Typically, this operation is carried out by temporarily disassembling a portion of the distribution conduit. 
     This is really inconvenient because it requires that the operator slide between the tubes and components of the seed-drill until he reaches the gate or component to be disassembled, actuate the distributor, re-mount the component removed or move the gate and then come back out of the narrow position previously reached. 
     The inconvenience is such that very often the operator cannot check that the gate has been precisely replaced in the correct original position and starts the distribution of the product in the field with a calibration device which is open and not completely closed. 
     As an alternative to that solution, there are also known seed-drills which are provided with a gate which can be actuated in order to open or close an aperture in the conduit mentioned above and to obtain selectively a calibration position and a sowing position. 
     The Utility Model DE 10 2010 002200 describes a calibration device for seed-drills in which a conduit for transporting the sowing products is selectively opened or closed by means of a slidable member. 
     During the sowing step, the member is withdrawn from the conduit, thereby leaving it open and allowing the material to arrive at the seed distributors. 
     Conversely, in a second position, the member is introduced in the conduit and blocks the flow of material by means of a wall thereof, redirecting it towards a discharge aperture, thereby allowing the calibration step. 
     However, that solution also has disadvantages. Although there is provided the possibility of using actuators for activating the member, the use of a sliding linear member involves a specific risk of jamming of the device owing to dust, sand, straw and other material which is in the working environment and which may readily become introduced into the sliding members of the member. 
     In addition, when it is in a calibration position, the member intercepts the conduit in which the flow of air mixed with the product to be sown flows and during the movement of the member material, which may partially obstruct the conduit or the other sowing elements, can also readily be moved inside the conduit. 
     SUMMARY 
     The problem addressed by the present invention is to provide a device for calibrating the above-mentioned functionalities which is structurally and functionally configured so as to allow all the disadvantages set out with reference to the cited prior art to be overcome. 
     This problem is solved by the invention with a calibration device constructed according to the appended claims. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The features and advantages of the invention will be better appreciated from the detailed description of a preferred but non-limiting embodiment thereof in which: 
         FIG. 1  is a schematic cross-section of a pneumatic seeding machine; 
         FIGS. 2 and 2A  are a lateral cross-section of the component of the machine of  FIG. 1  incorporating the device of this invention and a relevant detail; 
         FIGS. 3A and 3B  are two schematic side views, taken in section, which illustrate the operation of the device of the present invention in an operating calibration configuration and an operating distribution configuration, respectively; and 
         FIGS. 4A and 4B  are two front views of a distributor and a relevant gate, details of the device according to the present invention, illustrated in the operating calibration configuration and in the operating distribution configuration, respectively. 
     
    
    
     DETAILED DESCRIPTION 
     In the Figures, there is generally designated  1  a pneumatic seed-drill which is schematically illustrated in terms of only the main components. The seed-drill  1  comprises a receptacle  2 , in which the granular material to be distributed is contained, a fan  3  or other type of air compressor, a device for pneumatic transport  4  with a Venturi tube (Venturi below for the sake of brevity), in which the flow of air generated by the fan  3  flows together, a rotary distributor  5 , in particular provided with a bladed impeller  51 , and a diffusor  6  which receives the flow of air mixed with granular material to be distributed and supplies it to sowing elements which are illustrated by means of discharge conduits  7  which are connected to the diffusor by means of a tubular channel  71 . 
     As illustrated more clearly in  FIGS. 2 and 2A , the relationship between the above-mentioned components is such that the granular material contained in the receptacle  2  falls owing to gravitational force into the distributor  5  and is dispensed thereby in a through-conduit  8  which extends between the outlet of the distributor and a mixing chamber  41  of the Venturi  4  (and optionally including the Venturi itself), where it is mixed with an air flow and transported to the diffusor  6 . In particular, there is defined in the mixing chamber a through-hole  42  which is constructed in the region of a partition wall  15  between the transport device  4  and the distributor  5  and which opens in the through-conduit  8  in such a manner as to place them in communication with each other. 
     There is further provided in the through-conduit  8  a calibration aperture  9  which is normally closed by a gate  10  in the form of a blade which is articulated at one end to the conduit  8  and which can be pivoted away from and towards the aperture  9  in order to open or close it. Springs  12  or other locking devices retain the gate  10  in a closed position which is also indicated as the distribution position, restoring the continuity of the through-conduit  8 . 
     A linear actuator  11  of the electromechanical type is active between the fixed structure of the conduit  8  and the gate  10  in order to move it between the closed position mentioned and an open position which is also indicated as the calibration position, in which the granular material is dispensed through the aperture  9 , thereby bringing about the calibration step previously illustrated. The operative distribution and calibration configurations, with the gate  10  in the respective position, are illustrated in  FIGS. 2 and 2A , respectively, with a broken line (gate closed—distribution position) and solid line (gate open—calibration position). 
     As may be noted from those Figures, in the present embodiment when the gate  10  is in the open position, the flow of granular material is redirected by the gate  10  itself towards the aperture  9 , further preventing the flow from reaching the chamber  41 . Consequently, in the present embodiment, the gate  10  acts as a deflector of the flow. Alternatively, there may be provision for the aperture  9  to be arranged in a position below an outlet of the conduit  8 , in such a manner that, when the gate  10  is open, the granular material is directed towards the aperture  9  simply owing to the effect of gravitational force. In that case, therefore, an action for redirecting the flow will not be necessary. 
     In the actuator  11 , there are integrated a first and a second travel limit detector. Those travel limit detectors, which may also alternatively be constructed by means of external sensors, allow detection of whether the gate is in the open or closed position, consequently giving or not giving authorization for the calibration step of the distributor or for distribution over the whole field. 
     Those authorization signals are provided by means of suitable connection to a control unit which is not illustrated in the Figures and which, once the appropriate authorization has been received, allows or prevents the functions mentioned. 
     There is provision for the actuator  11  to be able to be of the electromechanical type, as in the present embodiment, or hydraulic, pneumatic, linear or rotary. There is further provision for it to be able to be unidirectional and for the opposite travel to actuation travel to be controlled by resilient return means, such as helical springs or the like. It must further be understood that, in the case of use of stepping motors, it may not be necessary to provide travel limit sensors, because such control is implicit in that type of actuation. 
     It is also known that the locking function brought about by the spring  15  may be brought about by the same actuator which may be controlled in such a manner as to keep the gate  10  locked in a closed position during normal operation of the seed-drill. Still as an alternative to the spring, or in combination with the spring, there may be provision, as a locking device, for a hook which is not illustrated in the Figures and which keeps the gate  10  locked in the closed position. 
     Finally, there is further provision for the distributor of the seed to be able to be rotated by an electric motor  52  in accordance with the authorization received by the control unit in order to drive the bladed rotor  51  of the distributor in rotation about its own axis for the number of rotations provided to carry out the calibration step. 
     The operation of the device according to the present invention is therefore schematically illustrated in  FIGS. 3A and 3B  which illustrate the seed-drill in the calibration step and sowing step, respectively. 
     During the calibration step, the granular material M is transported by means of the rotor  51  towards the through-conduit  8 . In that step, the gate  10  is arranged in the open position, in such a manner as to release the passage towards the calibration aperture  9 , directing the granular material M towards a receiving tank  91 , which is provided with a discharge  92 , illustrated in  FIG. 1 , from which the material used for the calibration may be recovered. At the same time, the gate  10  is arranged in such a position as to prevent the passage of the granular material M towards the chamber  41  and, more specifically, is arranged resting on the partition wall  15 , on which there is constructed the through-hole  42  between the through-conduit  8  and the above-mentioned chamber  41 , as can also be seen in  FIG. 4A . 
     As mentioned above, the gate  10  is articulated in the region of an end  101  thereof to the actuator  11  by means of an articulation shaft  13 . Furthermore, the gate  10  is additionally articulated by means of abutment between a vertex  102  thereof, or more generally an intermediate position thereof, and an edge of the calibration aperture  9 . It is evident that, as an alternative to abutment, there could be used a different articulation system such as, for example, a pin. The gate  10  which is secured in this manner is therefore able to move by means of actuation involving a piston and crank rod, in which the linear movement of the actuator  11  which coincides with the movement of the piston produces a rotation of the gate  10  with respect to the point of rotation defined by the abutment between the vertex  102  and the edge of the aperture  9 . 
     The movement of the actuator  11  may therefore move the gate  10  by means of a rotation movement in the closed position which is illustrated in  FIGS. 3B and 4B . In that position, the through-hole  42  from the conduit  8  towards the chamber  41  is released and, at the same time, it blocks the calibration aperture  9 . The granular material M may therefore continue towards the Venturi tube and become mixed with the air flow A therefrom, and thereby be directed to the diffusor  6 . 
     It is known, as better illustrated in  FIG. 4B , that the spring  12 , which is connected at one end to a pin  14  which is fixed to the wall  15  and at the other end to the shaft  13  controlled by the actuator, is maintained in a rest position when the diffusor is in a closed position. 
     Conversely, by the actuator  11  being actuated, the spring  12  becomes tensioned in such a manner that, in the absence of other forces, the gate  10  tends to move again into a closed position. 
     The invention described in this manner allows a number of advantages over conventional devices. In particular, the functionality and efficiency of the calibration step are improved and a higher level of safety for the user is ensured. 
     The use of a rotary gate actuated with a piston/rod system further allows a substantial reduction in the risks of the moving members becoming jammed owing to the presence of dust and other similar material present in the working environment. 
     In addition, it is possible with the device according to the present invention to prevent the redirecting gate from blocking or obstructing the air flow from the transport device, this being positionable in the region of the partition wall between it and the distributor. 
     Since the gate in the distribution position is maintained in abutment with the partition wall  15 , which delimits the mixing chamber  41 , it is not affected by the air flow produced by the ventilator. Furthermore, the rotation of the gate takes place in a direction away from the mixing chamber even in the calibration position. 
     Finally, with the distributor and the transport device being kept separate, it is possible to prevent, during the calibration step, a portion of the material from being able to be directed to the diffusor, thereby causing errors in the calibration step.