AGRICULTURAL SEPARATING DEVICE AND STARWHEEL SCRAPERS

Abstract: An agricultural separating device comprising a single rotatable member (2) having a plurality of starwheels (3) mounted on a rotatable shaft. A contra-rotating clod roller (5) is arranged parallel to and spaced from the single rotatable member (2) to provide a nip line (A) between the clod roller (5) and the rotatable member (2) for separating out material. Starwheel scrapers (4) are provided on the starwheels (3).

Description: Agricultural Separating Device and Starwheel Scrapers The present invention relates to an agricultural separating device incorporating starwheels, eg a root-crop harvester, particularly a potato harvester, and also relates to starwheel scrapers. Harvesters are known comprising rotatable members having a plurality of "starwheels" each having a plurality of outwardly extending resiliently deformable projections or "fingers". Such rotatable members are commonly referred to as "starshafts". GB 2 145 612B discloses a harvester having two rotatable members or "starshafts" upstream of a contra-rotating clod roller. In use crop, eg potatoes, is carried over the starshafts and clod and/or stones fall down therebetween. The potatoes, remaining clod and stones are then fed to the clod roller and, owing to the deformability of the starwheel fingers, most of the remaining clod and smaller stones are drawn between the contra-rotating starshafts and adjacent clod roller. In practice two starshafts are required with the starwheels ofthe starshafts staggered and interleaving, so as to provide a mutual self-cleaning action thereof and preventing a build-up of material between the starwheels. Harvesters are also known in which a conveying surface is formed from a plurality of starshafts and clod rollers, two starshafts being provided adjacent each clod roller arranged immediately downstream of the two starshafts. Starwheels wear out and therefore the provision of two starshafts adjacent each clod roller involves considerable expense in replacing the starwheels of each pair of starshafts. An object of the present invention is to provide an agricultural separating device in which the replacement of starwheels is reduced. The present invention provides an agricultural separating device as claimed in Claim 1. The provision of only one starshaft for each clod roller not only halves the cost of replacement starwheels, but also reduces the overall length ofthe harvester. Furthermore, such a harvester has fewer components and requires less power to operate. Any form of known starwheel scraper may be used. Starwheel scrapers are commonly used having a hub portion fitting loosely around the axially extending hub of a starwheel and a straight finger portion extending away from the hub portion. In one form of known scraper formed from bent rod, the finger extends tangentially away from the hub portion, and the scraper is known as a "P"- scraper. Alternatively, the finger may extend normally away from the hub portion so that the scraper has a shape similar to a hand mirror or magnifying glass. Although known scrapers perform their task of cleaning the soil adhering to the starwheels well, they are subject to considerable wear and tear and frequently become bent, and thereby cease to operate satisfactorily. A further object ofthe invention is to provide a starwheel scraper which in use is subject to less wear and tear than, but performs just as well as, known scrapers. The invention also provides a starwheel scraper as claimed in Claim 6. As a result of the convex surface of increasing radius of curvature, the scraper exerts a gradually increasing pressure on the soil adhering between adjacent starwheels, as the starwheels rotate, so that wear and tear on the scraper is considerably less. Thus, the life of starwheel scrapers according to the invention is significantly longer than that of conventional starwheel scrapers. If the starwheel scraper is moulded from plastics material, eg nylon, it may be manufactured easily, eg by injection moulding. Although the separating device in accordance with the invention may be provided with known starwheel scrapers, it is preferably provided with starwheel scrapers in accordance with the invention. Embodiments of the invention will now be described with reference to the accompanying drawings, wherein: Figure 1 is a diagrammatic side view of a separating device in accordance with the invention, Figures 2 and 3 are side views of known starwheel scrapers suitable for use with the separating device of Figure 1, Figure 4 is a side view of a starwheel scraper in accordance with the invention, Figure 5 is a front view of the scraper of Figure 4, Figure 6 is a side view ofthe scraper of Figure 4 mounted on a rotatable member, and Figure 7 is a side view of a further starwheel scraper in accordance with the invention. In Figure 1, the crop conveying surface 1 of an agricultural separating device, eg a potato harvester, has three spaced rotatable members ("starshafts") 2, 2 1 and 2 U each carrying axially spaced starwheels 3 and scrapers 4, to be described below. Contra- rotating clod rollers 5, 5 and 5 are arranged between the starshafts 2, 2 1 and 2 n and downstream thereof, respectively. Each clod roller 5, 5 1 and 5 U has a respective clod roller scraper 6, 6 1 and 6 n . As can be seen from Figure 1, the clod roller scrapers 6 and 6 1 act as stops for the scrapers 4 of the starshafts 2 1 and 2 U , respectively. Thus, if a lump of material clinging to the starwheels 3 is not removed by the scraper 4 hanging downwardly, the scrapers are carried clockwise until they strike against the clod roller scrapers 6 and 6 1 , respectively, and further rotation ofthe starwheels 3 in the anticlockwise direction results in a scraping away ofthe material from the starwheels 3 by the scrapers 4. A clod roller scraper 7 up-stream ofthe starshaft 2 similarly acts as a rotation limiter ofthe scraper 4 of starshaft 2. As can be seen from Figure 1 transverse lines of nip-points A, B and C extend between the starshafts 2, 2 1 and 2 U and the respective contra-rotating clod rollers 5, 5 1 and 5 π . It is the line of nip-points which provides the separation of clods from potatoes in a potato harvester, there being one line of nip-points for every starshaft 2, 2 1 , 2 n , whereas in harvesters not using starwheel scrapers, pairs of adjacent interleaving starshafts have to be provided up-stream of each contra-rotating clod roller to provide self-cleaning ofthe starwheels. Thus, for harvesters not having starwheel scrapers two rows of starshafts have to be provided for each line of nip-points, whereas for a harvester in which the starwheels have starwheel scrapers only one starshaft is required for each line of nip- points. Therefore, the number of starwheels required is half that required for the same number of nip-points when starwheel scrapers are used, resulting in lower starwheel replacement costs, lower power requirements for the harvester, fewer components and a shorter harvester. In Figures 2 and 3 known starwheel scrapers are shown. In Figure 2 the scraper 11 is known as a "P"-scraper and is formed from bent metal rod to form a circular hub portion 12 and a tangentially-extending finger 13. The hub portion 12 fits loosely around a laterally-extending hub 14 of the starwheel 3. The scraping action begins at a circumferential point A and ceases at point B, ie the scraping action extends over an arc of about 60°. In Figure 3 the scraper ll 1 has a "closed" hub portion 12 1 and a radially-extending finger 13 1 . Here, the scraping action is very rough and is effectively over an arc of only a few degrees. The known starwheel scrapers may be used with the crop conveying surface 1 of Figure 1. Figures 4, 5 and 6 show an improved starwheel scraper 4 in accordance with the invention. In these Figures the starwheel scraper 4 is formed from plastics material, eg injection-moulded nylon, and has a hub portion 15 with an aperture 16 therethrough and a finger 17 extending away from the hub portion 15. As can be seen from Figure 4, the scraper 4 has an outline somewhat similar to a "P"- scraper, but has an outwardly convex surface 18 with an increasing radius of curvature centred on the aperture 16. Beginning at a point A on the hub portion 15, the radius of curvature is constant for approximately 180° in an anticlockwise direction to a point B. For approximately a further 120° from point B to point C the radius of curvature ofthe hub portion 15 increases from η to r 2 . Thereafter, the outer surface ofthe scraper extends linearly along the finger 17 to the end 19. As can be seen from Figure 4, the inner surface 20 ofthe finger 17 extends radially from the aperture 16 with a radius r 3 substantially larger than r 2 . Figure 6 shows in side view part of an agricultural machine, eg a harvester or stone and clod separator ( a destoner) having two rotatable members comprising a plurality of starwheels 3 mounted on respective shafts 21, 22 of starshafts 23, 24 for rotation therewith. In Figure 6 the starwheels 3 interleave, and this provides a degree of self cleaning of the starwheels. However, if the starwheels are spaced so that they do not interleave (eg in the lifting conveyor and agricultural separator of EP 0 410 808B1), under certain soil conditions, if starwheel scrapers are not provided, the starwheels may become gummed up. It can be seen from Figure 6 that, as the starwheel 3 rotates in an anticlockwise direction, the separate fingers 3 ofthe starwheel 3 move past the convex outer surface 18 of the scraper 4 having a gradually increasing radius from point B to point C, ie over an arc of about 145°, after which the starwheel fingers 3 1 move behind the scraper finger 17. The gradual increase in radius ofthe outwardly convex surface 18 over an arc of about 145° produces a gradual scraping action over a longer period of time on material between starwheels 3, with a consequent reduction of pressure on the scraper and hence a reduction in wear and tear thereof. The starwheel scraper 4 1 of Figure 7 differs from that of Figures 4-6 mainly by the fact that the hub portion 15 1 has a gap 25 over about 90° of the circumference and begins at a hub end 26. The hub end 26 acts as a scraper for material adhering to the starwheel hub 14, and the gap 25 allows scraped material to fall away. Furthermore, the curvature of the outwardly convex surface 18 is not so pronounced as in the scraper 4 of Figures 4-6, and the inner surface 20 1 of the finger 17 1 is tangential, not radial, to the hub 14 ofthe starwheel 3. The radius ofthe convex surface increases gradually from the hub end 26 to a point D, where the ends ofthe starwheel fingers "disappear" behind the scraper finger 17 1 , ie over a circumferential arc of about 315°. This produces a very gradual scraping action with consequent lower wear and tear of the scrapers.

Claims: Claims; 1. An agricultural separating device comprising a single rotatable member (2) having a plurality of starwheels (3) mounted on a rotatable shaft, a contra-rotating clod roller (5) arranged parallel to and spaced from the single rotatable member (2) to provide a nip line (A) between the clod roller (5) and the rotatable member (2) for separating out material, and starwheel scrapers (4) provided on the starwheels (3). 2. An agricultural separating device as claimed in Claim 1, wherein there are a plurality of groups of the said single rotatable member (2, 2 1 , 2 U ) and respective said clod roller (5, 5 1 , 5 π ) arranged parallel to each other to form a conveying and separating surface (Fig. 1). 3. An agricultural separating device as claimed in Claim 2, wherein stop means (7, 6, 6 l ) are provided to limit rotation ofthe starwheel scrapers (4). 4. An agricultural separating device as claimed in Claim 3, wherein each clod roller (5, 5 1 , 5 11 ) is provided with a clod roller scraper as the said stop means. 5. A starwheel scraper (4) having a hub portion (15) with an aperture ( 16) therethrough, whereby the scraper may be loosely mounted on the hub (12) of a starwheel (3), and a finger (17) extending away from the hub portion (15), wherein the scraper (4) has an outwardly convex surface (18) with a radius of curvature (r,, r 2 , r 3 ) centred on the aperture (16) and increasing in a direction around the aperture (16) towards the finger (17) so that, in use, the scraper (4) exerts a gradually increasing pressure on material adhering to the starwheel (3). 6. A starwheel scraper as claimed in Claim 5 and formed from moulded plastics material. 7. A starwheel scraper as claimed in Claim 5 or 6, wherein the hub portion (15) has a substantially constant diameter for substantially 180° of its circumference (A B), whereafter the radius ofthe convex surface increases for substantially a further substantially 120° (B C) and thereafter the outer surface of the finger extends substantially linearly away from the hub portion (15) for the remaining substantially 60° (C A) of circumference ofthe hub portion (15). 8. A starwheel scraper as claimed in any one of Claims 5 to 7, wherein the inner surface (20) ofthe finger (17) extends substantially radially ofthe hub portion (15). 9. A starwheel scraper as claimed in Claim 5 or 6, wherein the hub portion (15 1 ) has a peripheral gap (25), so that an end (26) ofthe hub portion acts, in use, as a scraper ofthe hub portion (14) ofthe starwheel (3) on which it is mounted. 10. A starwheel scraper as claimed in Claim 10, wherein the convex surface (18 l ) begins at the said end (26) of the hub portion (15 ') and the radius ofthe convex surface (18 1 ) increases from the said end (26) for at least substantially 270° (D) and thereafter the finger (17 l ) extends substantially linearly away from the hub portion. 11. A starwheel scraper as claimed in Claim 9 or 10, wherein the inner surface (20 1 ) of the finger (17 1 ) extends substantially tangentially to the hub portion (15 1 ). 12. An agricultural separating device as claimed in any one of Claims 1 to 4, wherein the starwheel scrapers (4) are as claimed in any one of Claims 5 to 11. 13. A harvester comprising an agricultural separating device as claimed in any one of Claims 1 to 4 or Claim 12.

Inventors: WESTON DAVID BOOTH, WESTON, DAVID, BOOTH
Applicants: PEARSON RICHARD LTD, RICHARD PEARSON LIMITED
Application year: 1997
Main classification: B07B1
IPC codes: A01D17, B07B1