GB2195272A - Material-separating assemblies - Google Patents

Abstract

An array of open-centred cylindrical elements (16) hanging freely on a support bar (18) serve as a clod-crushing unit (14) associated with a conveyor sieve (12). In an alternative embodiment, an equivalent effect is achieved by means of individually pivotally supported roller elements extending in an array from side to side of the conveyor sieve. The elements may be biassed by gravity (the effect being adjustable, in the alternative embodiment, by means of counterweights), or springs towards the sieve (12). The assembly is especially intended for use in harvesting root crops e.g. carrots, but may be of more general application. <IMAGE>

Description

SPECIFICATION Material-separating assemblies The present invention relates to material-separating assemblies and in particular, but not exclusively, to soil-separating assemblies e.g.

for use in or with root-crop harvesters, in particular, but not exclusively, carrot harvesters.

According to the present invention, a material-separating assembly, e.g. for use with root-crop lifting means, comprises a conveyor sieve, and a rotary clod-crushing unit resiliently biassed towards the conveying surface of the sieve.

Conveniently, the rotary clod-crushing unit comprises an array of cylindrical elements each rotatable about an axis lying across the direction of motion of the conveyor sieve.

Conveniently, each said element is so mounted as to be able to move bodily relative to other of said elements in directions towards and away from the conveying surface of the sieve.

Conveniently, the cylindrical elements are gravity-biassed towards the conveying surface of the sieve.

Conveniently, in this case, the total maas of each element is equal to from 1/2 to 1 kg for each centimetre of element width measured in a direction parallel to said axis. In one such case, for example, the mass of each element is about 3 kg and the element width is about 4 cms.

Conveniently, when the elements are gravity-biassed, then they are also open-centred and hang freely on a transverse support member of smaller cross-section than the open centres of the elements. In one such case, for example, where the support member and those surfaces of the elements engaging the support member are both cylindrical, it is advantageous to have the difference in value between the internal diameter of the elements and the external diameter of the support member not greater than half the difference between the external and internal diameters of the elements.

As an alternative to having the cylindrical elements opencentred and hanging freely, each element or group of elements may instead be mounted on a respective pivotal support.

Conveniently, the material-engaging surfaces of the clodcrushing unit are free-wheeling.

The invention also includes a root-crop harvester incorporating a material-separating assembly according to the present invention.

The invention further includes a static material-separation plant including a material-separating assembly according to the present invention.

Embodiments of the invention will now be described, by way of example only, with reference to the accompanying drawing in which: Figure 1 illustrates, in simplified part-diagrammatic form, a perspective view of part of a darrot harvester according to the invention; and Figure 2 shows, in simplified part-diagrammatic form, part of a second embodiment of the invention.

Thus referring first to Figure 1 of the drawing, a carrot harvester in accordance with the present invention, comprises a continuous conveyor sieve or "web" 12 supported in the usual way and preferably of the so-called 'continental web" type comprising round-section steel rods flattened at each end and attached there to a continuous belt of composite material.

At the front end of the harvester, root-crop (and soil) is fed on to the conveyor sieve 12 for transport under the clod-crushing unit 14 which comprises an array of open-centred cylindrical elements 16 each hanging freely on a transverse support rod bar 18 extending from side-to-side of the sieve 12.

In the example illustrated in Figure 1, the outside and inside diameters of the elements 16 are respectively 180 mm and 80 mm, compared with an outside diameter of 30 mm for the support bar 18. With these dimensions, the interior of each said element will be at all times shielded from its surroundings by adjacent elements 16, whatever the relative displacement of any one element relative to its neighbours.

The thickness of each element 16 measured in a direction parallel to the longitudinal axis of bar 18 is typically in the range 20 mm to 40 mm and the elements 16 are preferably radiussed (not shown) at their outside corners with a radius of from 5 mm to 12 mm respectively, say.

Conveniently, the elements 16 would be constructed of aluminium alloy so as each to have a mass of from 1/2 kg to 1 kg, say, for each centimetre of element width measured as above described. This is equivalent to a mass lying in the range 2 kg to 4 kg for a 4 cm wide element, 3.3 kg being a typical value for an element 16 of these dimensions.

As an alternative, instead of the aluminium alloy elements above described, steel elements of the same mass and external dimensions could be used. These latter could conveniently each comprise a steel cylindrical section (of greater internal diameter than the aluminium alloy version) capped at each end with an annular steel plate of the same internal and external diameters as the aluminium alloy eie- ments so as similarly to restrict the freedom of movement of the individual elements on the bar 18.

A further alternative would be to construct the elements 16 of a lighter material than the alloy, for example PVC, with metal inserts included to bring the overall mass of the individual elements within the preferred range of 1/2 kg to 1 kg for each centimetre of element width. For example, in a prototype element currently under investigation, each element comprises a central cylindrical steel section of 1.6 cm width sandwiched between two cylindrical PVC sections each of 1.2 cm width, the density of the steel and the PVC being respectively 7.8 gms/ml and 1.5 gms/ml so as to give an overall mass of 3.3 kg for a 4 cm wide element of the same internal and external dimensions as the aluminium alloy elements of Figure 1.

Yet another alternative, is for the elements 16 to be spring-biassed towards the conveying surface of sieve 12 e.g. by using individual leaf springs bearing on the upper external surfaces of the elements.

In variations (not shown), elements 16 are profiled so as to increase the pressure per unit mass exerted by the elements, for example they could be externally grooved e.g.

with one or two grooves per element. In one such case, large diameter O-rings are set in the grooves to reduce the likelihood of damage to any crop engaged by the elements.

To avoid blockages, the support bar 18 is itself pivotally supported on two arms 20 which can displace upwardly if needs be to reduce the loading on the clod-crushing unit.

Reference numeral 21 indicates an adjustable stop, the position of which can be varied to control the severity of the clod-crushing operation as appropriate.

Turning now to Figure 2, this shows an alternative embodiment in which the clod-crushing unit 14 comprises a series of roller elements 30, the external dimensions of which may lie in a similar range to those discussed in regard of the elements 16 of the first em embodiment In this second embodiment, there is no freedom of movement between the elements 30 and their supporting axle, the equivalent effect being achieved instead by having each element supported on a cranked arm 32 pivoted at 34. The effective weight of the gravity-biassed elements 30 is controlled by movement of a counterweight 36 along the second section of arm 32 as shown.

Although the illustrated assemblies have been described as incorporated in a carrot harvester, it will be appreciated that they are equally suited for incorporation, with minor modifications if necessary, into other forms of root-crop harvester, e.g. harvesters for potatoes, sugar beet and possibly also daffodil bulbs etc. and also potato diggers. By way of example, the size of the elements 16, 30 might be increased to an outside diameter of 250 mm say, to deal with potatoes as the harvested crop.

Briefly, the more important design features of at least the illustrated embodiments of the invention are that the clod-crushing elements 16, 30 should present a continuous barrier to the flow of crop and clods on the sieve 12, and that the risk of damage and/or obstruction is limited by forming the crop-engaging convergence of the clod-crushing unit 14 of two freely-moving surfaces.

It should also be borne in mind that the elements 16, 30 are likely to prove most effective if they are positioned towards the top end of the sieve 12 to prevent loose soil and small clods acting as a cushion.

In addition, it is important that each clodcrushing element 16, 30 should preferably be free to move independently of its neighbours as described and that the clearance between these elements and the conveyor web 12 should be adjustable. In this latter respect, the pressure exerted on the clods by the opencentred elements 16 of the Figure 1 embodiment can be selected at the design stage through an appropriate choice of materials for the elements (e.g. steel, alloy or plastics etc.) and the whole assembly can be pivoted as shown at 22, 23 to allow passage of large foreign objects e.g. bog oak, under the unit 14. In the Figure 2 embodiment, the same effect is obtained by having the pivot 34 sufficiently distanced from the web 12.

As bolt-on assemblies, the clod-crushing units 14 of Figures 1 and 2 could be fitted to most designs of harvester provided that the desired clearance between the elements 16, 30 and the web 12 is maintained by supporting the latter on an appropriate pair of web support rollers (not shown).

The invention also extends to a static material-separation plant having a material-separating assembly of any of the kinds above described in accordance with the present invention.

Claims (14)

1. A material-separating assembly, comprising a conveyor sieve, and a rotary clod-crushing unit resiliently biassed towards the conveying surface of the sieve.

2. An assembly as claimed in Claim 1 in which the rotary clodcrushing unit comprises an array of cylindrical elements each rotatable about an axis lying across the direction of motion of the conveyor sieve.

3. An assembly as claimed in Claim 2 in which each said element is so mounted as to be able to move bodily relative to other of said elements in directions towards and away from the conveying surface of the sieve.

4. An assembly as claimed in Claim 2 or Claim 3 in which the cylindrical elements are gravity-biassed towards the conveying surface of the sieve.

5. An assembly as claimed in Claim 4 in which the total mass of each element is equal to from 1/2 to 1 kg for each centimetre of element width measured in a direction parallel to said axis.

6. An assembly as claimed in Claim 5 in which the mass of each element is about 3 kg and the element width is about 4 cms.

7. An assembly as claimed in any of Claims 4 to 6 in which the cylindrical elements are open-centred and hang freely on a transverse support member of smaller cross-section than the open centres of the elements.

8. An assembly as claimed in Claim 7 in which the support member and those surfaces of the elements engaging the support member are both cylindrical, and the difference in value between the internal diameter of the elements and the external diameter of the support member is not greater than half the difference between the external and internal diameters of the elements.

9. An assembly as claimed in any of Claims 4 to 6 in which each said element or group of elements is mounted on a respective pivotal support.

10. An assembly as claimed in any preceding claim in which the material-engaging surfaces of the clod-crushing unit are free-wheeling.

11. A material-separating assembly substantially as hereinbefore described with reference to, and/or as illustrated in, Figure 1 of the drawing.

12. A material-separating assembly substantially as hereinbefore described with reference to, and/or as illustrated in, Figure 2 of the drawing.

13. A root-crop harvester incorporating a material-separating assembly according to any of Claims 1 to 12.

14. A static material-separation plant including a material-separating assembly according to any of Claims 1 to 12.