Abstract:
A machine for the sorting by size of pear-shaped objects including a conveyor ( 10 ) able to move essentially horizontally. The conveyor includes a first alignment of equidistant and parallel primary rollers ( 30 ) separated each from the next by an interval allowing one object to pass through. The conveyor ( 10 ) also has a second alignment of secondary rollers ( 44 ) each arranged in alignment with an interval. The machine has a device ( 42 ) for guiding the secondary rollers ( 44 ) along a sorting path ( 14 ) of the conveyor. The guide device ( 42 ) being such as to move the secondary rollers progressively away from the primary rollers along the length of the sorting path ( 14 ). The primary and secondary rollers do not rotate about their axis for the greater part of the sorting path ( 14 ).

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a machine for the sorting by size of pear-shaped objects of the type comprising a conveyor, which is able to move essentially horizontally. The conveyor has a first alignment of equidistant parallel primary rollers separated each from the next by an interval allowing one object to pass through. The conveyor also has a second alignment of secondary rollers each arranged in alignment with an interval, which secondary rollers are able to move perpendicular to the plane of travel of the primary rollers. The machine has means to guide the secondary rollers along a sorting path of the conveyor, and the guide means being such as to progressively move the secondary rollers away from the primary rollers along the length of the sorting path. 
     2. Description of Related Art 
     Such a machine is disclosed for example in Patent Application FR-A-2 473 364. In that machine all of the primary and secondary rollers are rotated about their parallel axes. 
     Machines of the above type are used particularly for sorting generally spherical fruit or vegetables such as apples and oranges according to size. 
     The machine is not however suitable for pear-shaped fruit or vegetables, that is fruit or vegetables having the general shape of an oval with a more or less narrow end. Examples of fruits having this shape are pears, avocados and courgettes. 
     What is found is that the rotation of the rollers causes the objects being sorted to rotate themselves. The effect of the rotation, when applied to oval objects with a narrow end, is that the objects are caused to work their way towards one or other of the ends of the rollers. This migration of the objects along the length of the rollers injures them and crushes them, thereby impeding the normal operation of the machine. 
     SUMMARY OF THE INVENTION 
     It is an object of the invention to provide a machine for the sorting by size of pear-shaped objects that does not have the drawbacks mentioned above and which in particular prevents the transverse displacement of the objects during the sorting process. 
     To this end the subject of the invention is a machine for the sorting by size of pear-shaped objects, of the aforementioned type, characterized in that the primary and secondary rollers do not rotate about their axis for the greater part of the sorting path. 
     In accordance with certain particular embodiments, the machine has one or more of the following characteristics: 
     (1) the machine has means for positioning the objects with their longitudinal axis essentially parallel to the primary and secondary rollers; 
     (2) the positioning means comprise an auxiliary roller feeder whose rollers are rotated slowly about themselves and means of transfer from the auxiliary feeder to the conveyor with little or no modification to the orientation of the objects; 
     (3) the positioning means are built into the conveyor, the conveyor comprising, upstream of the sorting path, an object receiving section, along the length of which the primary and secondary rollers are rotated slowly about themselves in order to position the objects; and 
     (4) the machine comprises a plurality of elastically deformable adjacent revolving rollers located immediately beneath the sorting path in order to soften the fall of the objects. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     A clearer understanding of the invention will be gained from reading the following description, which is provided purely by way of example and refers to the drawings in which: 
     FIG. 1 is a side view of the sorting machine according to the present invention; 
     FIG. 2 is a partial view in cross section of the sorting machine according to the present invention; and 
     FIGS. 3 and 4 are partial cross sections taken in the direction of the length of the upper side and lower side of the composite conveyor of the machine. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     The machine according to the invention is shown in FIG.  1 . It is designed to sort pears on the basis of their size. 
     The machine comprises a roller conveyor  10  forming an endless loop and travelling between two terminal drums  12 , one of which is a drive drum. Along an upper side, the conveyor  10  defines a known sorting path  14 . Along its other side the conveyor defines a return path. 
     Between the two sides of the conveyor are four endless feeders  20  for conveying the fruit towards the packaging centers. Each endless feeder  20  is associated with fruit of one particular size. These feeders extend horizontally and at right angles to the conveyor  10 . Between the feeders  20  and the upper side of the conveyor  10  are means  22  for receiving the sorted fruit by softening their fall as they come off the conveyor  10 . 
     The machine also comprises an auxiliary endless feeder  24  that supplies-the fruit to be sorted. This feeder is advantageously a roller feeder that supplies the fruit to the entrance of the sorting path  14 , the pieces of fruit being separated by a predetermined constant interval. The feeder  24  has rollers turning upon themselves at slow speeds, for example at a speed of 100 rpm for a conveyor having a linear-speed of 20 m/min. 
     The auxiliary feeder  24  is particularly suitable for ensuring that the pieces of fruit arrive on the sorting path  14  with their longitudinal axes parallel to the plane of movement of the conveyor  10  on the sorting path and perpendicular to the direction of advance of the conveyor. The pieces of fruit therefore reach the sorting path with their axes parallel to the rollers of the conveyor  10 . 
     In addition, the machine comprises, between the auxiliary feeder  24  and the sorting path  14 , a ramp  26  and a presser roller  28  that accompanies the descent of the fruit from the feeder  24  to the entrance of the sorting path  14 , without the orientation of the axis of the fruit being modified. 
     As illustrated in FIGS. 2 and 3, the conveyor  10  is equipped with an alignment of primary rollers  30  extending parallel to each other. These rollers are arranged essentially horizontally and perpendicular to the direction of advance of the conveyor on the sorting path  14 . They are equidistant and define intervals through which the largest size of fruit to be sorted can pass. The primary rollers  30  are carried at their ends by endless chains  32  between the terminal drums  12 . 
     At each end, the rollers  30  have, on their spindles, shoes  33  with at least one flat. 
     Along the horizontal path forming the sorting path  14 , the shoes  33  rest on horizontal sliding tracks  34  mounted on either side of the conveyor  10  on a machine frame  36 . 
     The rollers  30  are preferably covered with an elastic and flexible material, and at their ends have annular enlargements that exert a retaining action on the fruit to be sorted. 
     In the intermediate part of each segment of the chain  32 , which lies between two consecutive rollers  30 , that is to say in alignment with the intervals separating two rollers, a plate  40  is attached to the chain. This plate extends at right angles to the plane of the rollers, that is vertically above the sorting path  14 . The plate  40  contains a slot  42  that extends at right angles to the plane of the rollers. These slots act as guides for a second alignment of rollers  44 , termed the secondary rollers, which are driven by the chains  32 . This guidance takes place in a direction at right angles to the direction of travel of the primary rollers  30 . 
     The slots  42  take the ends of the spindles of the rollers  44 , these rollers being identical to the rollers  30 . In this way the rollers  44  lie and travel parallel to the rollers  30 . 
     On the ends of the spindles of the rollers  44 , beyond the plates  40 , are shoes  46  resting on guide ramps  48 . These shoes  46  include at least one flat. 
     The guide ramps  48  are carried by a moveable gantry  50  whose slope is adjustable relative to the frame  36  by screw-and-nut adjustment means  52 . 
     The ramps  48  are inclined relative to the horizontal, and in particular relative to the sorting path  14  defined by the sliding surfaces. The surface on which the shoes  46  rest rises progressively along the sorting path. 
     On the sorting path  14 , the rollers  30  and  44  are unable to rotate about their axis relative to the chains  32 . Their only movement is therefore that of translation imparted by the chains. The non-rotation of the rollers is obtained by the shoes  33  and  46 , each with a flat that rests on the tracks  34  and  46 . 
     The non-rotation of the rollers  30  and  44  means in the particular context that the rollers are not intentionally rotated by any mechanism of the machine. However, they can be mounted idly, in which case they are mechanically independent of the machine&#39;s drive systems. 
     The means  22  that receive the pieces of fruit take the form of revolving brushes  62  lined up beneath the sorting path and extending parallel to each other. The brushes  62  are tangential to each other and are rotated in the same direction. 
     It will be realized that, as the primary rollers  30  and secondary rollers  44  travel along the upper side of the conveyor defining the sorting path  14 , the secondary rollers, though initially lying virtually on the same level as the primary rollers, progressively move away from these. As a result, each piece of fruit introduced from the feeder  24  initially rests on a primary cylinder and on a secondary cylinder. As it travels along the sorting path  14 , the gap between the primary and secondary rollers eventually becomes great enough for the fruit to drop through between two primary rollers, whereupon it is received on the brushes  62  situated underneath. These brushes then accompany the fruit as it drops onto the feeder  20  where all fruit of the same size is received. 
     It can be seen that as the primary and secondary rollers are not rotated, the pear-shaped fruit can be sorted satisfactorily and without the danger of being crushed. 
     Furthermore, the presence of the revolving brushes  62  forming elastically deformable adjacent revolving rollers softens the fall of the fruit and saves it from being spoiled by sudden impacts. 
     In particular, in the case of pears, the perforations caused by the stem of one pear penetrating another pear are averted. 
     In one particular embodiment, the upper side of the feeder has two consecutive sections. On the first section forming a fruit receiving section, the primary and secondary rollers are rotated slowly to allow correct positioning of the fruit with its axis parallel to the rollers. On this section, roller rotating means of any suitable type are employed. The speed of rotation of the rollers is approximately 100 rpm for a linear speed of advance of the conveyor of approximately 20 m/min. 
     On the receiving section, the gap between the primary and secondary rollers is minimal and constant. 
     The receiving section is followed by a sorting section analogous to the sorting path described above. On this sorting section, the primary and secondary rollers do not rotate about their axis and the secondary rollers move progressively away from the primary rollers as they advance. 
     Referring to FIG. 4, it can be seen that providing guides also on the lower side of the conveyor to support the shoes  33  and  46  with which the rollers  30  and  44 , respectively, are equipped, and by constructing the rest as described above in respect of the upper side of the conveyor, it is also possible to use the lower side of the conveyor for sizing the fruit. By adding a small number of other parts, the already high productivity of the machine can therefore be doubled, with the obvious advantages resulting from this possibility.