Abstract:
An apparatus for conveying and/or transferring relatively vulnerable products, such as fruits, wherein the fruits are held in grippers while being conveyed and transferred. The grippers comprise a first gripper portion and a second gripper portion, which are movable over sliding elements substantially in the direction in which the gripping force is exerted on the products.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application claims priority to The Netherlands Application NL 1016186 filed Sep. 14, 2000, and The Netherlands Application NL 1016453 filed Oct. 20, 2000, which applications are herein incorporated by reference in their entirety. 
     BACKGROUND OF THE INVENTION 
     The sorting of fruits takes place at increasingly higher speeds, for example at speeds of 7-15 fruits per second. Because of said high speeds, the fruits may be damaged upon being transferred from a first conveyor to a second conveyor, which is undesirable. 
     From European patent application EP A 0 687 508 there is known a conveyor which is fitted with grippers. Said grippers are used for conveying products to individual stations. Consequently, a relatively large number of gripping hands are required. Furthermore, flexible arms are used on the grippers so as to be able to engage fruits of varying diameter. 
     SUMMARY OF THE INVENTION 
     The present invention provides an apparatus for conveying and/or transferring relatively vulnerable products, such as fruits, wherein the fruits are held in grippers while being conveyed and transferred, wherein said grippers comprise a first gripper portion and a second gripper portion, which are movable over sliding elements substantially in the direction in which the gripping force is exerted on the products. 
     Furthermore, the present invention provides an apparatus for transferring vulnerable products, such as fruits, from a supply conveyor to a discharge conveyor, wherein said fruits are held in grippers and wherein the said products that are present in said grippers are weighed while being transferred. 
     Preferably, a pivoted suspension on the outer side is used, so that it is possible to use a three-point support so as enable a stable weighing process. Furthermore, the bearing sliding surfaces for said three-point weighing are preferably spaced apart as far as possible. 
     The present invention also provides a method for conveying and discharging one or more fruits, wherein: 
     the fruits are separated from each other in a singling device; 
     the individual fruits are taken out of said singling device by means of grippers and transferred to a conveyor fitted with product carriers, during which transfer the individual fruits are weighed; and 
     wherein said fruits are discharged from the conveyor with the product carriers, by tilting said product carriers and causing the fruits to move past a flexible element. 
     The above method enables a relatively simple construction of the appropriate apparatus, in particular of the conveyor fitted with product carriers, since weighing takes place in the grippers. 
     With a view to obtaining a calibration hallmark, it is important that the apparatus be standardized, that is, that a fixed number of parts and a fixed length of (a weighing portion of) the apparatus are used. 
     It is possible, however, to set a different track width, for example by adjusting the pin length, for example for fruits ranging in a diameter between 22 mm and 250 mm. 
     In the past, the applicant furthermore marketed an apparatus wherein fruits were sorted and discharged at specific positions in dependence on measured quantities, such as weight, size, colour and the like. A slab of a flexible material was used during the discharge of the fruits so as to reduce the velocity thereof. Since the fruits were weighed in the fruit carriers, said slab was in fact detached from the cup or fruit carrier and it was fitted near the front side thereof—seen in the conveying direction. As a result, said slab had a considerable length of about 30 cm, for example, which caused quite some inconvenience in the device when discharging took place into water channels, because the long slabs scooped up (a great deal of) water. In dry discharging situations, the long slab had an abrasive effect on the fruits, which had an negative effect on the quality of said fruits. 
     The present invention furthermore provides an apparatus for conveying and discharging vulnerable products, such as fruits, comprising: 
     product carriers that can be moved in the conveying direction; 
     tilting means for causing the product carriers to tilt at a specific conveying position, so as to discharge the product from the product carrier in rearward direction, seen in the conveying direction, at said conveying position; 
     wherein a product carrier is provided laterally of a conveying element, wherein the product carrier can be returned to the conveying position after the fruit has been discharged, and wherein a flexible element is disposed on the rear side of the product carrier for the purpose of discharging the product from the product carrier in a controlled manner. 
     The apparatus according to the present invention has been optimized for conveying and discharging fruits, both in the situation in which the products are carried off without water being used and in the situation wherein water channels are used. With the apparatus according to the invention, the weighing process has preferably taken place already, so that it is possible to attach a much shorter slab, for example a slab having a length of 15 cm, to the rear edge. 
     The apparatus according to the present invention does not produce much noise, not even at high speeds. The present invention makes it possible to conveyor more than five fruits (such as apples) per second, for example 7-9 fruits per second, wherein the construction of the apparatus and the controlled discharging speed prevent vulnerable fruits being damaged. Preferably, the fruits are placed into the carriers by grippers, as a result of which the quality, for example of apples, remains ensured, even at the aforesaid high speeds. 
     In one preferred embodiment, each product carrier is furthermore provided with a snap mechanism for discharging the fruits in a reliable manner and pushing the product carrier back into the conveying position and securing it in said position as soon as possible after a product has been discharged, so that the slab need not drag over next products and will not scoop water in the situation wherein water is used. 
     In another preferred embodiment, a product carrier is approximately S-shaped in section, seen in the conveying direction, which has appeared to be the most advantageous shape for various types of fruits having varying dimensions. The fruit is properly engaged (on the convex surface thereof), using the lowest possible pressure forces, whilst discharging is facilitated. 
     In order to enable the gripping hands to engage properly, the product carrier has an approximately S-shaped profile in cross-sectional view as well. 
     The present invention furthermore provides a method for conveying and discharging one or more fruits, wherein: 
     products carriers containing fruits are moved in the conveying direction; 
     the respective product carriers are tilted at specific conveying positions, and the respective fruits are discharged in rearward direction from said product carriers into a water channel; and 
     wherein the fruit is slowed down upon being discharged by means of a flexible element which is attached to the rear edge of the product carrier. 
     This method, which is preferably carried out in combination with the apparatus according to claims  12  and  13 , enables a practical realisation of such an apparatus, since the trouble which the water causes to the chain and other parts of the conveyor is significantly reduced. 
    
    
     DESCRIPTION OF THE FIGURES OF THE DRAWINGS 
     Further advantages, aspects and details of the present invention will be elucidated in the description hereafter, in which reference is made to the appended drawings, wherein: 
     FIG. 1 is a side view of a first preferred embodiment of an apparatus according to the present invention; 
     FIG. 2 is a perspective top plan view of the apparatus of FIG. 1; 
     FIG. 3 is a partially broken-away, perspective view of the apparatus of FIGS. 1 and 2; 
     FIG. 4 is a perspective view of detail IV of FIG. 3; 
     FIG. 5 is a side elevation of the detail of FIG. 4; 
     FIGS. 6A and 6B are perspective views of the elements of FIGS. 4 and 5, respectively showing the open position and the closed position thereof; 
     FIG. 7 is a partially schematic, sectional view of a preferred embodiment of an apparatus according to the present invention; 
     FIG. 8 is a perspective view of detail II in FIG. 1; and 
     FIG. 9 is a perspective view of a unit as used in the apparatus according to FIGS.  1  and  2 . 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     A device  1  (FIGS. 1,  2  and  3 ) comprises a fixed number of gripping hands  2 , thirty-four pairs in the present embodiment, for transferring fruits that are being supplied in the direction indicated by arrow A by a first conveyor  3  to a second conveyor  4 , wherein the fruits are carried off in fruit carriers  5  in the direction indicated by arrow B. Fruits that are not suitable for direct consumption can be discharged, for example via a third discharging conveyor  6 . The device furthermore comprises a frame  7 , with chain wheels for endless chains, to which the gripper hands are attached, being suspended therein. 
     The open gripper hands  2  are preferably each provided with a cover  41  (see FIG. 4) of a soft material so as to enable a proper engagement of the fruits V whilst minimizing the risk of damaging the fruits. As is clearly shown in FIGS. 2 and 3, device  1  comprises a motor  11  for driving chains  18  with the gripper hands attached thereto, as well as a chain tensioning device  12 , which is fitted with a coil spring  19  (FIG. 3) and cup springs  14  for the purpose of compensating for changes in the length of the chain as much as possible. A first part  15  of said chain tensioning device  12  (FIG. 3) is spaced from a second part  16 , which is fixedly connected to the mounting bracket for the chain wheel  17  to which the driving motor  11  is connected. The cup springs  14 , coil spring  19  and the possibility of movement along the sloping surfaces thus enable springing movement of the part  16  comprising the motor and the chain wheels. The first part  15  is fixedly connected to the frame. 
     The respective gripper hands  2  that are fitted between chains  18  are movable over pins  43  and  44  (FIG. 4) in a direction transversely to the conveying direction. As is also apparent from FIGS. 5 and 6B, the respective gripper hands are suspended from pins  43 ,  44 . Said pins are fixed to the frame parts  45  and  46 , which are connected to the chain in such manner as to be capable of slight pivoting movement, which movement is made possible by knee  47 , among other parts. 
     Furthermore, connecting pieces  51 , see also FIG. 5, are provided between successive pairs of gripper hands for the purpose of allowing vertical movements between successive pairs of gripper hands. 
     Three supporting surfaces present at the bottom side of frame parts  45  and  46  are each passed over a platform  48  that forms part of a so-called load cell  49  for weighing a fruit which is held by the gripper hands. As the number of gripper hands is limited, it is certainly within the bounds of the possible that in the future a calibration hallmark will be obtained for this accurate manner of weighing products. At present, calibrated weighing generally takes place manually in the final packaging. Since the apparatus according to the present invention comprises a limited number of gripper hands, for example 25-100, the cost that is involved can remain within bounds. 
     Frame parts  45  and  46  are preferably made of an easily sliding or resilient plastic material. Experiments have furthermore shown that in the case of speeds of up to 15 fruits per second, 10-50 msec are available for determining the weight in an accurate and stable manner, which is made possible by the three-point support. 
     Gripper hands  2  are movable from an open position as shown in FIG. 6A to a closed position as shown in FIG. 6B by means of cams  61 , which are movable, along with the gripper hands  2 , over sliding rods  43  and  44  against the action of a coil spring  62 . The supporting parts  45  and  46  for weighing are pivotally connected to chains  8 , whilst the knees  47  that are fitted between the two pairs can pivot independently of each other. Parts  45  and  46  are thus pivotally connected to pins  65 , which are each fixedly connected to chains  18  so as to ensure independent weighing of the pairs that are positioned adjacently to each. 
     With an apparatus  70  (FIG. 7) according to the present invention, vulnerable products, such as apples A, are transported by means of fruit carrier  72  to discharging positions, preferably water channels  73  and  74 , two of which are shown in FIG. 1, whilst in practice dozens of discharging positions are available, at which positions the fruits can be sorted according to size, weight, quality, colour and the like. In FIG. 7, housings  75 ,  76  are indicated highly schematically, in which housings cameras for sorting the fruits A according to colour may be disposed, for example. The fruit carriers  72  are transported by means of endless chains  78 , which circulate via chain wheels  79  and  80 . If a fruit is to be discharged at discharging location  74 , a fruit carrier is released at that location, so that said fruit carrier will tilt about a pin  72  and fruit A will be discharged via a sloping surface  83  and a slab  84  that is attached to fruit carrier  72 . 
     As is apparent from FIGS. 8 and 9, a unit  30  consisting of two fruit carriers  72 , each fitted with a slab  84 , is provided with hook ends  91  and  92  for connecting unit  90  to (and above) chain  78  and to a rail  94  extending below chain  78 , respectively. Nose lips  93  ensure the fixation in longitudinal direction with respect to chain  78 . 
     The fruit carriers are S-shaped in section, both in the conveying direction and in a direction transversely thereto. In practice said S-shaped section has provided to be suitable for various types of fruits. The S-shape in transverse direction enables proper engagement of the fruits present in carriers  72  by the grippers—see for example Dutch patent application no. 1016168 (not pre-published). 
     Since the fruit carriers are disposed relatively high with respect to the chain, the fruits can be readily engaged therein and/or be deposited therein, for example by means of the aforesaid grippers. The use of grippers makes it possible to increase the velocity of the fruit carriers, whilst the presence of the slab does not result in a greater spacing between the fruit carriers. 
     Hook ends  95  are present on either side of the product carriers  72 , which hook ends are engaged in a snap mechanism  96  in the conveying position, which snap mechanism comprises an operating lever  97  and a springing portion  98 , which snap mechanism is preferably integrally formed of plastic material with a carrier and/or a central portion  100  of unit  90 . 
     As is apparent in particular from FIG. 8, a guide element  102  is provided near every discharging position, such as the one at water channel  74 , which guide element forms a curved track along which the fruit carriers are guided, that is, along the downward flank of the curved track during discharging and along the upward flank after discharging at a preceding discharging position so as to return the fruit carriers to the conveying position. An actuating mechanism  103  is provided near guide element  102  for moving a fruit carrier  72  from the conveying position to the discharging position. Said mechanism  103  comprises an electrically actuated rod  104 , which actuates lever  105  upon upward movement, which lever in turn actuates the lever  97  of a respective fruit carrier unit, as a result of which the hook  95  is detached from the snap mechanism  96  and the fruit is carefully discharged as a result of the presence of the downward flank of curved element  102 , guide plate  83  and slab  84 . The invention is not restricted to the above-described preferred embodiments thereof; the rights applied for are determined by the claims hereinafter, within the scope of which all kinds of modifications are conceivable.