Method and apparatus for conveying and cleaning bulbous and tuberous plants, and a lifter comprising such apparatus

Abstract: The invention relates to a method and apparatus for conveying and cleaning bulbs and tubers such as potatoes, wherein the potatoes are carried by two adjacent rollers (7), which rollers rotate about their longitudinal axis in opposite directions, with the longitudinal axes being inclined in one direction. By driving the rollers (7) for oscillation, the potatoes are alternately moved in the direction of the conveying surface (4) and in a direction away from the conveying surface and simultaneously at least by shocks moved down along the conveying surface (4). The alternation of the direction of movement of the rollers prevents stagnation of the processing and cleaning of the potatoes.

Description: This invention relates to a method for conveying and cleaning bulbous and tuberous plants such as potatoes, whereby bulbs or tubers are supplied to the upper end of a slightly inclined conveying surface by means suitable therefor, the conveying surface comprising parallel rollers drivable for rotation about their longitudinal axis and having a substantially unprofiled surface, with pairs of adjacent rollers forming a carrying groove in which the tubers can be carried, the rollers are driven for rotation, in such a manner that adjacent rollers always rotate in opposite directions, and the tubers are guided to the lower end of the conveying surface by the rotating rollers and are simultaneously stripped of adherent dirt by the rollers. Such a method is known from practice. To facilitate the description, only potatoes will be mentioned as bulbous and tuberous plants. In the known method, which is for instance practised in lifters for potatoes, the potatoes are fed onto an inclined conveying surface at the upper end thereof, this conveying surface consisting of parallel rollers which are continuously driven for rotation, with pairs of adjacent rollers being driven in opposite directions. Depending on the continuous direction of rotation of the rollers, potatoes disposed in a V-shaped groove defined by the relevant adjacent rollers are either lifted and possibly deposited in an adjacent groove, or pushed towards the underside of the groove in that the rollers rotate in the direction of the underside of the groove. During the continuous rotation of the rollers, due to the friction between the rollers and the potatoes or the adherent dirt such as clay or earth, the potatoes are stripped of at least a part of that dirt, which is discharged downwards between the rollers. As a result of the inclination of the conveying surface, during normal use the potatoes are moreover guided in the direction of the lower ends of the rollers. However, if for instance a relatively solid lump or a stone ends up between the rollers or, for instance, an elongate object is deposited in the longitudinal direction of the groove, potatoes disposed in the same groove are no longer conveyed downwards because they cannot pass the object in question which is stationary with respect to the groove and the conveying surface. As a result, the conveying action of the apparatus is adversely affected and moreover there is a risk of the potatoes being damaged. In order to overcome the above conveyance problem, previously a method has been proposed which utilizes adjacent rollers which alternately have an at least substantially smooth outer surface and a spiral outer surface. The rollers with the spiral outer surface then function as conveyor screws. Two adjacent rollers form a carrying groove through which the potatoes, mainly as a result of the rotation of the spiral rollers, are conveyed to the lower end of the conveying surface. Any dirt on the potatoes, such as adherent clay and earth, is scraped off the potatoes by the rollers, in particular due to the friction developing between the potatoes or the dirt and the rollers, and due to the profile of the spiral rollers knocking against the potatoes, and then discharged downwards between the rollers. In this known method, the potatoes are positively advanced in the direction of the lower end of the conveying surface, but there is a risk of the potatoes being damaged severely, in particular by the profiled conveyor rollers. The object of the invention is to provide a method of the type described in the preamble, by which the above-mentioned disadvantages are avoided, while the advantages are maintained. To that end, the method according to the invention is characterized by the features according to claim 1. The use of relatively unprofiled rollers prevents the possibility of the potatoes being damaged by the rollers. The potatoes are cleaned by the friction only, that is, the brushing action that arises. By virtue of the rollers rotating alternately in one direction and the other, any objects caught between the rollers, such as for instance non-rolling objects, solid lumps and stones, are loosened upon reversal of the direction of rotation and, together with the potatoes disposed in the carrying groove in question, are at least temporarily brought into a completely or substantially floating position relative to the conveying surface. In the process, due to gravity and the movements of the rollers, they are passed to some extent in the direction of the lower end of the conveying surface. Moreover, upon reversal of the direction of rotation of the rollers, the potatoes and any dirt can be thrown into another, adjacent groove, whereby they are likewise passed to some extent in the direction of the lower ends of the rollers. As a result, the potatoes follow either a straight or, for instance, a substantially zigzag path over the conveying surface and are simultaneously cleaned thoroughly, without the potatoes being damaged, while moreover objects on the conveying surface are prevented from interfering with the conveying action. The invention further relates to an apparatus for conveying and cleaning bulbous or tuberous plants, suitable in particular for practising a method according to the invention. This apparatus is characterized, in accordance with the invention, by the features according to claim 6. The invention moreover relates to a lifter or harvester for bulbs or tubers, in particular a potato lifter, which lifter comprises an apparatus according to the invention and/or is arranged for practising a method according to the invention. To clarify the invention, an exemplary embodiment of an apparatus and a method are described with reference to the drawings. Fig. 1 shows a front view of a conveying and cleaning apparatus for bulbous and tuberous plants, in particular potatoes, with a potato in a first position; Fig. 2 shows in front view the apparatus according to Fig. 1, with the potato displaced to some extent; and Fig. 3 shows in side elevation the apparatus according to Fig. 1. In the drawing a part of a potato harvester is shown, with supply means 1 for the potatoes 2, which are lifted from a field by means not shown. The supply means 1 are depicted as a bar conveyor. The supply means 1 connect to the upper end 3 of an inclined conveying surface 4 which will be further explained hereinafter. Connecting to the lower end 5 of the conveying surface 4 are suitable discharge means 6 for potatoes, for conveyance of the potatoes, for instance to a collecting vehicle, not shown in the drawing. The conveying surface is made up of a number of rollers (nine in the drawing) 7 1 - 7 9 , extending at least substantially parallel to each other. Adjacent its upper end 3 and its lower end 5, each roller 7 is rotatably suspended in suitable bearings 9 through a rotary pin 8 extending in the longitudinal direction of the roller. Accordingly, the rollers 7 extend substantially parallel to the direction of inclination of the conveying surface 4. The outer surface 10 of each roller is substantially unprofiled and between two adjacent rollers 7 1 , 7 2 a gap 11 has been left clear. Accordingly, pairs of adjacent rollers 71, 72 form a V-shaped carrying groove 12, open towards the underside 13 of the conveying surface 4 due to the gap 11. In the embodiment shown in the drawing, the conveying surface therefore comprises eight carrying grooves 12 1 - 12 8 . It is noted that in some cases the rollers 7 may also wholly or partly abut each other. The rollers 7 are drivable for rotation by drive means 14 which in the embodiment shown in the drawing are connected to the rollers adjacent the upper end 3 of the conveying surface 4. These drive means 14 comprise, for instance, a gear or belt drive 15, adapted for rotating two adjacent rollers 7 1 , 7 2 in opposite directions. In addition, reversing means 16 are included for the oscillatory drive of the rollers 7. The operation of these means will be further elucidated hereinafter. The drive means 14 can be connected, for instance via a conventional coupling shaft, to the output shaft of a tractor vehicle, not shown, or be provided with an autonomous drive, for instance a diesel or petrol engine or an electric motor. The spacing of the bearings 9 of the rollers 7 transversely to the direction of the inclination of the conveying surface 4 is adjustable in that the bearing supports 17 are secured in slotted holes or on a tooth track. Thus the width of each gap 11 between two rollers 7 can be set depending on the crop to be processed and the extent of fouling thereof. In addition, at at least one of the ends 3, 5 of the conveying surface 4, the bearing supports 17 can be adjusted in vertical direction, enabling adjustment of the angle of inclination of the conveying surface relative to the horizontal. An apparatus according to the invention can be used as follows. Suitable rollers 7 are chosen depending on the product to be processed. In the case of large products, rollers 7 of a relatively large diameter will be used and a relatively large width of the gap 11 will be set, while in the case of smaller products thinner rolls 7 will be used and narrower gaps 11 will be set. Moreover, in the case of strongly fouled and/or relatively firm products, rollers 7 with a slightly rough surface 10, for instance rubber rollers, can be used and in the case of relatively clean and/or easily damaged products, rollers with a smooth surface 10, for instance steel rollers, can be used. For instance, stainless steel rollers can be used, in particular because of their good corrosion resistance. Further, rollers with different surfaces can be combined. The rollers 7 are driven for rotation by means of the drive means 14, with the gearbox 15 being of such design that adjacent rollers always rotate in opposite directions. If the left-most roller 7 1 in the drawing rotates counterclockwise (Fig. 1), the second roller 7 2 rotates clockwise, the third roller 7 3 counterclockwise, etcetera. Further, the reversing means 16 drive the rollers 7 1 -7 9 for oscillation. This means that the rollers are first rotated through a particular turn in a first direction (Fig. 1) and then through a particular turn, preferably the same turn, in the opposite direction (Fig. 2). The turn made by the rollers 7 is adjustable with the aid of the drive means, and is preferably more than 360°, for instance four or five complete revolutions in either direction. For the drive of the rollers 7, drive means 14 are provided, which, in the embodiment shown in Fig. 4, comprise a belt drive 15 and a reversing device 16. A drive belt 20, preferably a toothed belt, extends alternately along the top of a first roller 7 1 , the underside of the adjacent second roller 7 2 , the top of an adjacent third roller 7 3 , etcetera. The belt 20 drives, for instance, seven rollers. The belt 20 further extends along a blade 21 1 of a multi-bladed first drive wheel 21 which, via a second drive belt 22, preferably a chain, over a second sheet 21 2 is driven by a second drive wheel 23. The second drive wheel 23 is driven via a crank mechanism 24 by a continuously running motor 28. The crank mechanism 24 comprises a first, relatively long shaft 25 having one end connected to the second drive wheel 23 and the other end to a first end of a second, relatively short shaft 26 which has its other end connected to the motor shaft 27 continuously drivable for rotation. The length of the short shaft 26 is less than the radius of the second drive wheel 23. The belt 20 is tensioned by a tensioning wheel 29. As a result of the rotation of the motor shaft 27, the short shaft 26 of the crank mechanism is rotated at a substantially continuous angular speed. Via the long shaft 25 the second drive wheel 23 is thereby moved. Due to the short shaft 26 being shorter than the radius of the drive wheel 23, the second drive wheel 23 swings back and forth between two extreme positions less than 360° apart relative to the axis of rotation of the second drive wheel. Via the first 20 and the second drive belt 22, the rollers 7 are thereby brought into a back-and-forth movement. The ratio between the diameters of the rollers 7, the blades 21 1 , 21 2 of the first drive wheel 21, the diameter of the second drive wheel 23 and the lengths of the long 25 and short shaft 26 of the crank mechanism then determine the number of turns the rollers make during each back or forth movement of the second drive wheel 23. These ratios can be adjusted, for instance by exchanging rollers 7, drive wheels 21 or blades thereof and/or shafts 25, 26 of the crank mechanism 24. Via a coupling shaft 30 the movements of the second drive wheel 23 can be transmitted to a similar apparatus, not shown in the drawing, by coupling it to a further second drive wheel. In this coupled apparatus, the motor 28 and the crank mechanism 24 can then be omitted and by an appropriate choice of dimensions synchronously moving rollers 7 are obtained. Thus, series of rollers can be driven. Of course, many other alternative embodiments are possible. In a state fouled with, for instance, sand, clay and possibly stones and the like, potatoes 2 are thrown onto the conveying surface 4 adjacent the upper end thereof by means of the supply means 1 and divide over the carrying grooves 12 1 -12 8 . The potatoes 2 are then entrained by the rollers 7 in the direction of a gap 11 in a carrying groove 12, which is defined by two adjacent rollers 7 moving in the direction of the underside of the V-shaped carrying groove 12 in question. In Fig. 1 they are, viewed from the left, the second 12 2 , fourth 12 4 , sixth 12 6 and eighth carrying groove 12 8 , in Fig. 2 the first 12 1 , third 12 3 , fifth 12 5 , and seventh carrying groove 12 7 . For convenience, the description will be limited to the three leftmost rollers 7 1 , 7 2 , 7 3 in Figs. 1 and 2 and the two carrying grooves 12 1 , 12 2 formed between them. A potato 2 fouled with clay, for instance, has been fed into the right-hand carrying groove 12 2 (Fig. 1) adjacent the upper end of the conveying surface 4 and is carried therein by the rollers 7 2 , 7 3 . Because the rollers rotate, they remove the clay from the potato as a result of the friction developed between the clay and the rollers, and entrain the clay towards and through the gap 11 at the bottom of the carrying groove 12 2 , so that the clay can be readily discharged. Lumps and the like that fall into the same groove 12 2 are either squeezed by the rollers 7 2 , 7 3 and discharged through the gap 11, or carried in the carrying groove 12 2 like the potatoes 2. After the rollers 7 have rotated through a number of turns in one direction, the reversing means 16 reverse the direction of rotation, so that the potatoes 2 are carried from the second carrying groove 12 2 by, and possibly over, the second roller 7 2 into the first carrying groove 12 1 . The potatoes can move substantially straight down, as shown in Figs. 1 and 2 in the fourth carrying groove 12 4 from the left, or they can traverse a substantially zigzag path P, as shown on the left in Figs. 1 and 2. For convenience, hereinafter only the zigzag path P is described. The potatoes 2 and stones and the like, if any, come completely or substantially clear of the rollers 7 upon reversal of the direction of rotation of the rollers 7, as a result of which they move readily, inter alia under the influence of gravity. Owing to the conveying surface 4 being arranged at an inclination, the potatoes 2 thereby move to some extent in the longitudinal direction of the first 7 1 and the second roller 7 2 in the direction of the lower end 5 of the conveying surface 4. In the first carrying groove 12 1 the potatoes 2 are further cleaned until the direction of rotation of the rollers is reversed again and the potatoes are returned to the second carrying groove 12 2 . As a consequence of this method, the potatoes 2 follow a substantially zigzag path P over the conveying surface 4 in the direction of the lower end 5, while dirt is removed from the potatoes and discharged through the gaps 11. It is noted that the course of the path P naturally depends on all kinds of other factors, such as the degree of filling of the conveying surface, the extent of engagement of the potatoes by the rollers, the shape and dimensions of the potatoes, the extent of fouling of the rollers and the potatoes and the like. The path P may therefore have a variety of forms other than straight or zigzag. The oscillating motion of the rollers 7 prevents, for instance, a stone from getting "caught" between the rollers and coming to a substantial standstill relative to the conveying surface. A stone or like object is discharged in corresponding manner to the potatoes, so that the processing of potatoes over the conveying surface is not subject to stagnation and damage to the potatoes is prevented, while the potatoes are yet cleaned in optimum manner. Adjustment of the angle of inclination of the conveying surface 4 enables control of the distance over which the potatoes are passed over the conveying surface in the direction of the lower end 5 upon each reversal of the direction of rotation. Adjustment of the turn made by the rollers in either direction as well as of the speed of rotation enables control of the time during which the potatoes are cleaned. The greater the turn, the longer the cleaning time, the higher the speed, the greater the cleaning power. Further, variation of the width of the gap or the width of the carrying groove then enables control of the force which is then exerted on the potatoes by the rollers: if the carrying groove 12 is relatively narrow with respect to the potato 2, the potato is barely contained in the groove and only a lower part of the potato will be engaged by the rollers, while in the case of a relatively wide groove 12 the potato can be engaged from the sides. Furthermore, means may be included for setting a maximum drive power in order to prevent damage to the rollers owing, for instance, to a stone between the rollers. This may moreover prevent a potato from being engaged too roughly and damaged. It may be advantageous to arrange the rollers 7 in the conveying surface 4 in such a manner that the longitudinal axes 8 of two adjacent rollers include an acute angle, in such a manner that the gap 11 is narrower at the lower end 5 of the conveying surface 4 than it is at the upper end 3. As a result, potatoes disposed at the upper end of the conveying surface 4, which are fouled to a greater extent and hence are relatively thick, are subject to more force for cleaning them than are potatoes disposed lower on the conveying surface, which are cleaner. Advantageously, the rollers 7 adjacent the outer sides of the conveying surface can be bearing-mounted at a slightly higher level than are the intermediate rollers 7. Thus the potatoes 2 are simply protected from falling laterally off the conveying surface. By alternating rollers 7 of different roughnesses in the conveying surface (for instance rollers 7 1 , 3 , 5 , 7 , 9 of relatively smooth metal, the others of rougher rubber), the zigzaggy path P over the conveying surface 4 desired for the potatoes is substantially fixed, since the potatoes 2 will be principally entrained by the rougher rollers. Moreover, the potatoes 2 in the carrying grooves 12 are then caused to rotate approximately transversely to the direction of the inclination of the conveying surface 4 inasmuch as the rougher roller engages the dirt on the potatoes better than the smoother roller does, so that in such cases an even better cleaning is obtained. For the purpose of cleaning the rollers 7 during, prior or after use, a scraper 18 is arranged along the underside 13 of each roller in the longitudinal direction thereof, which scraper 18 extends throughout the length of the roller, approximately centrally under the centerline of the roller 7 in question. The distance between the scraper 18 and the outer surface 10 of the roller is adjustable by means of adjusting means 19, such as for instance set bolts. During the rotation of the rollers 7, dirt on the rollers that is thicker than the width of the gap between a scraper 18 and the roller 7 n in question is simply scraped off the roller by the scraper 18, so that the dirt drops. It is noted that the rollers 7 may instead or additionally be rinsed or sprayed clean with water or the like. The invention is not in any way limited to the embodiments shown in the drawing and described in the description by way of example only. Many variations are possible. For instance, the description mentions only potatoes as bulbous or tuberous crops, but naturally many other crops can be processed with a method and apparatus according to the invention. Moreover, such an apparatus or method can also be used, for instance, with crops that are supplied from a bunker or silage pit or in different apparatuses. The rollers may be provided with a brush-shaped surface and the bristles may to some degree extend in the direction of the lower end of the conveying surface for the purpose of a better advancement of the potatoes. In this embodiment the potatoes can also be conveyed over a substantially horizontal surface or even up a slope. The rollers can be composed of all kinds of suitable materials. The number of rollers in the conveying surface, the length thereof and the diameter can be chosen as desired and even during use be adjusted depending on the circumstances. The drive means can be designed in different ways, obvious to those skilled in the art. For instance, use can be made of gear, rope and/or belt transmission, link systems and different kinds of drives. For instance, each roller may be equipped with a gear wheel adjacent the upper end, with the gear wheels of the rollers meshing in pairs. Each pair of rollers is driven by a drive wheel of the reversing device, meshing, for instance, with the left-hand gear wheel. When reversing the direction of rotation, the drive wheel is shifted, in such a manner that the drive wheel disengages and is then engaged with a right-hand gear wheel of an adjacent pair of gear wheels. As a result, the direction of rotation of the rollers is reversed. Further, the various adjusting and control functions can be controlled both electronically and mechanically. These and many other modifications are understood to fall within the scope of the invention.

Claims: A method for conveying and cleaning bulbous and tuberous plants (2) such as potatoes, whereby bulbs or tubers (2) are supplied to the upper end (3) of a slightly inclined conveying surface (4) by means (1) suitable therefor, the conveying surface (4) comprising parallel rollers (7) drivable for rotation about their longitudinal axis and having a substantially unprofiled surface (10), with pairs of adjacent rollers (7) forming a carrying groove (12) in which the tubers can be carried, the rollers (7) are driven for rotation, in such a manner that adjacent rollers (7) always rotate in opposite directions, and the tubers (2) are guided to the lower end (5) of the conveying surface (4) by the rotating rollers (7) and are simultaneously stripped of adherent dirt by the rollers (7), characterized in that the rollers (7) are driven for oscillation, through a number of degrees to the left and then through a number of degrees to the right, whereby the rollers (7) upon inversion of the direction of rotation, cause the tubers (2) to move slightly upwards from a carrying groove (12) and possibly to an adjacent carrying groove (12), and the tubers (2) are simultaneously moved in the direction of the lower end (5) of the conveying surface (4), while dirt is removed from the tubers (2) by the rollers (7) and is urged through the underside (11) of the carrying grooves (12). A method according to claim 1, characterized in that the angular displacement of the rollers (7) is set depending on the nature and size of the tubers (2) to be cleaned and the nature and extent of fouling thereof, all this in such a manner that the tubers (2) are urged by two adjacent rollers (7) in the direction of the underside (11) of the carrying groove (12) formed between said two adjacent rollers (7) for such a time that the desired cleaning is obtained by friction between the rollers (7) and the tubers (2) without the tubers thereby being damaged. A method according to any one of the preceding claims, characterized in that the rollers (7) are rotated through at least 360° in either direction, with the angular displacement of each roller (7) being equal to the angular displacement of the other rollers. A method according to any one of the preceding claims, characterized in that the spacing of the rollers (7) is set depending on the nature and size of the tubers (2) to be cleaned and the nature and extent of fouling thereof, all this in such a manner that the tubers (2) can be carried in the carrying grooves (12), to a depth sufficient for contaminations to be scraped off their circumferential surface, without the tubers (2), whether or not in cleaned condition, slipping through the rollers (7). A method according to any one of the preceding claims, characterized in that the tubers (2) are lifted from a field and are supplied substantially directly to the upper end (3) of the conveying surface (4). An apparatus for conveying and cleaning bulbous or tuberous plants (2), which apparatus comprises an inclined conveying surface (4) which comprises a number of parallel rollers (7) having a substantially unprofiled surface (10), the rollers (7) being bearing-mounted (8) for rotation about their longitudinal axis and the longitudinal axes extending approximately parallel to the direction of inclination of the conveying surface (4), with means (14) being included for driving the rollers for rotation, the rollers (7) being arranged such that between the rollers (7) slightly V-shaped carrying grooves (12) are defined which can at least partly be open at the underside (11), the drive means (14) for the rollers being adapted for driving two adjacent rollers (7) in opposite directions during use, characterized in that the drive means (14) for the rollers (7) are adapted for driving the rollers for oscillation, the arrangement being such that the rollers (7) are alternately drivable through at least a part of a revolution and preferably through a number of revolutions in a first direction and are then drivable in the opposite direction. An apparatus according to claim 6, characterized in that adjusting means are included for controlling at least the maximum turn of the rollers (7) during each oscillation. An apparatus according to claim 6 or 7, characterized in that means are included for controlling the driving speed of the rollers. An apparatus according to any one of the preceding claims 6-8, characterized in that means are included for setting the spacing between the rollers (7). An apparatus according to any one of claims 6-9, characterized in that means are included for adjusting the angle of inclination of the conveying surface. An apparatus according to any one of claims 6-10, characterized in that the rollers (7) are provided with at least a rubber or metal surface (10). An apparatus according to any one of claims 6-11, characterized in that means are provided for setting the maximum drive power of the rollers (7). An apparatus according to any one of claims 6-12, characterized in that the longitudinal axes of two adjacent rollers (7) include an acute angle. An apparatus according to any one of claims 6-13, characterized in that the conveying surface (4) is slightly concave transversely to the direction of the inclination. A lifter for bulbs or tubers, in particular a potato lifter, which lifter comprises an apparatus according to any one of claims 6-14 or is arranged for practising a method according to any one of claims 1-5.

Inventors: VAN DIJKE D, VAN DIJKE, D.
Applicants: KONSTRUKTIE EN MACHINEBOUW VAN, KONSTRUKTIE- EN MACHINEBOUW VAN DIJKE ZEELAND B.V.
Application year: 1995
Main classification: B07B1
IPC codes: F02B1, B07B1, A01D17