WO1997041973A1

WO1997041973A1 - Machine for sorting particulate material

Info

Publication number: WO1997041973A1
Application number: PCT/IL1997/000130
Authority: WO
Inventors: Victor Grozubinsky; Ilya Tamarkin
Original assignee: V.G. Sep Ltd.
Priority date: 1996-05-03
Filing date: 1997-04-20
Publication date: 1997-11-13
Also published as: IL118128A0; AU2575497A

Abstract

A machine (10, 110) for sorting particulate material, which includes feed apparatus (12, 412, 512, 612, 712) for providing a continuous feed of particulate material, and having an inlet (20) and an outlet (22); rotor apparatus (14, 114, 414, 614, 5114, 6114, 7114) arranged beneath the outlet (22) and mounted for rotation about a vertical axis so as to accelerate incoming constituent particles of the particulate material fed thereto via the outlet (22) of the feed apparatus (12, 412, 512, 612, 712) in directions outward relative to the vertical axis, along helical trajectories (46, 120) whose respective radial distances from the vertical axis at different elevations generally correspond to preselected physical properties of the particles, wherein the particles are subsequently allowed to fall generally downwards; apparatus (55) for rotating the rotor apparatus at a rotational speed preselected in accordance with the type of particulate material sought to be separated, and collector apparatus (16, 416, 516, 616, 716) for dividing the falling particles into groups, each having different characteristic properties.

Description

MACHINE FOR SORTING PARTICULATE MATERIAL

FIELD OF THE INVENTION The present invention relates to sorting of particulate materials.

BACKGROUND OF THE INVENTION

Various machines for sorting particulate materials are known in the art, many of which are based on rebound properties exhibited by materials of different types. It is also known to sort single types of materials into sub-groups, each representing different physical characteristics of the material, such as weight, size and the like.

Included in known art are US Patents Nos. 4,195,735; 4,625,872; 4,744,470 and 5,271 ,506, and International Patent Application No. PCT/AU87/00155. All of these publications describe devices for sorting particulate materials by impinging a volume of particulate material on a deflector, from which the individual particles rebound along trajectories of different lengths, depending on the elasticity, size, weight, shape and general aerodynamic properties of the particles. Compartments are placed at different distances from the deflector, so as to sort the particles into a number of groups.

Disadvantages of the above devices include relatively slow volumetric sorting rates and, in many of them, the flow of particulate material both to and from the deflector, is such that trajectories of particles upstream of the deflector can intersect with those downstream of the deflector, causing interference, and thus reducing the reliability of the sorting

A further disadvantage of the above devices is that no provision is made for adjusting them so as to permit use thereof with different types of materials

In the area of harvesting seed crops (seed and grain for sowing), there are a number of known sorting stages of a harvested 'admixture' which follow a stage of precleaning of the admixture. These sorting stages are based on sorting in accordance with size, weight, mechanical integrity, and predicted germination rate. To the best of the knowledge of the present inventor, there does not exist in the art a single machine which is capable of sorting a cleaned admixture in accordance with the above-mentioned parameters SUMMARY OF THE INVENTION It is an aim of the present invention to provide an improved particle sorting machine which overcomes disadvantages of the prior art

In particular, the present invention aims to provide a particle sorting machine which is capable of reliably sorting particulate material at large volumetric flow rates, and of different types

It is furthermore an aim of the present invention to provide a particle sorting machine which is capable of sorting particles of a single species in accordance with predetermined physical characteristics

Yet a further aim of the present invention is to provide a machine for sorting seeds, gram and the like, in accordance with different physical parameters known in the sorting of agricultural seed admixtures

There is thus provided, in accordance with a preferred embodiment of the invention, a machine for sorting particulate material including feed apparatus for providing a continuous feed of particulate material_, and having an inlet and an outlet, rotor apparatus arranged beneath the outlet and mounted for rotation about a vertical axis so as to accelerate incoming constituent particles of the particulate material fed thereto via the outlet of the feed apparatus, in directions outward relative to the vertical axis, along helical trajectories whose respective radial distances from the vertical axis at different elevations generally correspond to preselected physical properties of the particles, wherein the particles are subsequently allowed to fall generally downwards, apparatus for rotating the rotor apparatus at a rotational speed preselected in accordance with the type of particulate material sought to be separated, and collector apparatus for dividing the falling particles into groups, each having different characteristic properties

Additionally in accordance with a preferred embodiment of the invention, the rotor apparatus has a generally conical outward-facing particle acceleration surface which defines a predetermined acute angle with respect to the vertical axis

Further in accordance with a preferred embodiment of the invention, there is also provided an annular plate member arranged about the vertical axis and vertically above the rotor apparatus, and wherein the plate member is positioned such that the accelerated particles impinge thereupon so as to be rebounded therefrom in generally helical outward and downward directions In accordance with an alternative embodiment of the invention, the rotor apparatus has a generally cup shaped configuration and defines a side wall having a generally upward- and inward-facing particle acceleration surface which defines a predetermined acute angle with respect to the vertical axis.

Further in accordance with a preferred embodiment of the invention, the outlet of the feed apparatus is arranged to permit the continuous supply of the particulate material to the rotor apparatus under the influence of gravity, and the outlet is generally circular in cross-section and is arranged symmetrically about the vertical axis, thereby to permit a 360° distribution of supplied particulate material.

Additionally in accordance with a preferred embodiment of the invention, the feed apparatus includes apparatus for adjusting the size of the opening of the outlet through which the particulate material is supplied to the rotor apparatus. This may be either manually operated or computer controlled.

Further in accordance with a preferred embodiment of the invention, the collector apparatus includes a plurality of generally annular, concentric, trough-like compartments, separated by a corresponding plurality of dividing elements, each arranged at a predetermined radial distance from the vertical axis, such that each compartment defined therebetween receives a plurality of falling particles each having similar physical characteristics.

Each compartment has a floor portion on which falling particles impinge, after which they come to rest. Preferably, these compartments are lined with a resilient floor layer which is operative to partially absorb impact energy of particles impinging thereof, thereby reducing rebound of these particles after impinging on the resilient floor layer.

In accordance with a further alternative embodiment of the invention, the machine includes at least first and second sorting stages arranged along the vertical axis, the rotor apparatus is first rotor apparatus located in the first stage, and the collector apparatus includes: the plurality of generally annular, concentric compartments located in the second stage; and an additional, generally cone-shaped compartment, arranged symmetrically about the vertical axis beneath the first rotor apparatus, and having an outlet, for receiving particles falling within a predetermined radial area about the vertical axis and for providing them to the outlet, wherein the machine further includes second rotor apparatus located along the vertical axis in the second stage, between the outlet of the cone-shaped compartment and the collector apparatus, and wherein the second rotor apparatus is mounted for rotation about the vertical axis so as to accelerate incoming constituent particles of the particulate material, fed thereto via the outlet of the cone-shaped compartment, in outward directions along helical trajectories whose respective radial distances from the vertical axis at different elevations correspond to preselected physical properties of the particles, wherein the particles are subsequently allowed to fall generally downwards, thereby to further sort the particulate material

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will be more fully understood from the following detailed description, taken in conjunction with the drawings, in which

Fig 1A is a schematic side view illustration of a single stage particle sorting machine, constructed in accordance with a first embodiment of the invention employing rotational deflection apparatus,

Fig 1 B is a cross-sectional view of the machine of Fig 1A, taken along line B-B therein,

Fig 2 is a schematic side view illustration of a single stage particle sorting machine constructed in accordance with a second embodiment of the invention,

Fig 3A is a schematic side view illustration of a single stage particle sorting machine, similar to that of Fig 2, but also employing stationary deflection apparatus,

Fig 3B is a cross-sectional view of the machine of Fig 3A, taken along line B-B therein,

Fig 4 is a schematic side view illustration of a double stage particle sorting machine, constructed in accordance with a third embodiment of the invention, employing in both stages rotational deflection apparatus similar to the rotational deflection apparatus seen in Fig 1A,

Fig 5 is a schematic side view illustration of a double stage particle sorting machine similar to the embodiment of Fig 4, but employing rotational deflection apparatus in the upper stage similar to the rotational deflection apparatus seen in Fig 2A,

Fig 6 is a schematic side view illustration of a double stage particle sorting machine similar to the embodiment of Fig 4, but employing rotational deflection apparatus in the lower stage similar to the rotational deflection apparatus seen in Fig 2A, Fig. 7 is a schematic side view illustration of a double stage particle sorting machine employing in the upper stage rotational deflection apparatus which is similar to the rotational deflection apparatus seen in Fig. 2A;

Fig. 8 is a schematic side view illustration of a collector apparatus such as may be used in place of the collector apparatus of any of the machines shown and described above in conjunction with Figs. 1A-7;

Fig. 9A is a cross-sectional illustration of a spreader member and a single downwardly-extending element, taken along line A-A in Fig. 8;

Fig. 9B is a part-sectional elevation taken along line B-B in Fig. 9A;

Fig. 10 is a schematic diagram of a particle sorting machine employing computer-controlled means for adjusting the rate of feed in the machine, in accordance with yet a further embodiment of the invention;

Fig. 11 is a diagram showing the distribution of vetch grain sorted by the machine of the present invention, in accordance with grain humidity;

Figs. 12A-12D are graphs showing pea seeds sorted into different fractions by the machine of the invention in accordance with physical integrity of the seeds and showing also a correlation with humidity;

Fig. 13 is a diagram showing a correlation between the germination of seeds and their sorting by elasticity associated parameters;

Fig. 14 is a graph showing time dependence of the germination of different sorted fractions of tomato seeds; and

Figs. 15A-15C are graphs similar to Fig. 14, but showing results for each fraction when the machine is operated at different rotational speeds.

DETAILED DESCRIPTION OF THE INVENTION Referring now to Figs. 1A and 1 B, there is provided a particulate material sorting machine, referenced generally 10, constructed and operative in accordance with a preferred embodiment of the present invention. Machine 10, as well as the various embodiments shown and described below, are useful for efficiently sorting any sort of particulate material in which different types of constituent particles have different physical characteristics generally, and different elasticities in particular.

As described below in conjunction with Figs. 11-15C, the inventors have found that, use of the present machine for sorting a single type of material, such as seeds, grain or other agricultural produce, provides a direct correlation between elasticity, and various other parameters that may be useful, particularly humidity and germination rate In particular, the machine of the present invention is useful in sorting agricultural produce for seed purposes which, as known in the art, undergoes several stages of sorting between harvesting and marketing as seed While the results shown in Figs 11-15C relate specifically to data gathered employing a machine constructed in accordance with the embodiment of Figs 1A and 1B, similar results are also to be expected in the use of machines constructed in accordance with other embodiments of the invention, as described below in conjunction with Figs 2A-7

Referring now to Figs 1A and 1 B, machine 10 has a feeder 12, a rotor 14, and collector apparatus, referenced generally 16, all of which are oriented along a common vertical axis 18 In general, particulate material is fed from feeder 12 through which it descends, preferably under the influence of gravity, to rotor 14 Rotor 14 is operative to deflect incoming particles along generally helical outward trajectories, and the deflected particles fall into any of a plurality of compartments in collector apparatus 16

In more detail, the feeder 12 is preferably a funnel-shaped member, having a top opening 20 for receiving a volume of particulate material, and having a bottom outlet 22 Feeder 12 is mounted in a generally vertical orientation along vertical axis 18 Feeder 12 includes an adjustable flow regulator, referenced generally 24, which may be operated so as to adjust the size of the opening of the opening via which the particulate material enters outlet 22 This is particularly useful, as different types of particulate material require different opening sizes so as to permit sorting thereof By way of example, it is clear that, in order to obtain satisfactory rates of sorting of, for example, hops, which are relatively large, and tomato seeds, which are relatively small, the hops will require outlet 22 to be opened to a great extent, while only a small opening may be necessary for sorting the tomato seeds

As seen in Fig 1 A, flow regulator 24 includes a typically conical plug 26 having a wide base 28 whose diameter Do is approximately equal to the internal diameter Di of the feeder outlet 22 Plug 26 is mounted for axial translation along a guide 30 aligned along vertical axis 18 Plug 26 has formed therein, at least at an upper portion 32 thereof, an internal screw thread 34 which cooperates with the thread of an elongate screw member 36 which is rotated as by means of a handle 38 Screw member 36 extends thorough an end portion 40 of a supporting arm 42, which is rigidly attached, as by way of example, to a portion 44 of machine housing 45 It will thus be appreciated that rotation of handle 38 in one direction causes plug 26 to be raised and thus withdrawn from outlet 22, thereby enlarging the size of the available opening, while rotation of the handle 38 in the opposite direction causes retraction of the plug 26 into the outlet, thereby reducing the size of the available opening.

Rotor 14 has formed thereon a generally conical outward-facing particle acceleration surface, referenced 15, which is oriented at an acute angle α with respect to vertical axis 18, in the range 15-60°. Rotor 14 is arranged beneath outlet 22 and is mounted for rotation about axis 18 such that incoming constituent particles of the particulate material, fed thereto via feeder outlet 22, are engaged by particle acceleration surface 15. The rotating acceleration surface 15 accelerates the particles outwardly along helical trajectories, as indicated by arrows 46, seen also in Fig. 1 B.

It is a particular feature of the invention that the particles are deflected along helical trajectories whose respective radial distances from vertical axis 18 correspond, at different vertical elevations relative to rotor 14, to preselected physical properties of the particles, including size, weight, shape, humidity and so on. This is discussed in more detail below in conjunction with Figs. 11-15C. The particles subsequently fall downwards towards the collector apparatus 16, which is operative to collect the falling particles and to divide them into groups, each group having different characteristic properties.

Referring now also to Fig. 1B, it is seen that collector apparatus 16 is formed primarily of a plurality of annular, trough-like compartments, referenced 48, 50, 52 and 54, each spaced symmetrically about axis 18. The velocity of each particle as it is accelerated outwardly from rotor 14, combined with various physical characteristics, determines the length of its trajectory and thus into which compartment it will fall, thus providing an indication of preselected properties. The compartments are separated by generally vertical collectors or wall elements 56, and each compartment further has respective outlets, 48', 50, 52' and 54', provided in a floor portion 58. A rotating spreader member, referenced 60, is also provided. As seen, spreader member 60 is a boom-like member which extends diametrically across the floor of the machine, and which has a plurality of downwardly extending elements 62 for spreading particles accumulated in each compartment so as to prevent particles in one compartment from overflowing into an adjacent compartment, and, further, for causing outflow of the particles through outlets 48', 50, 52' and 54' and into containers or onto conveyors (not shown). A particular feature of the sorting machine of the present invention is that rotor 14 is driven by a suitable type of electric motor, referenced 55, whose speed may be varied It has been found by the Inventor that the rotor speed may be advantageously varied so as to the provide variable sorting of particulate material in accordance with different preselected criteria Typically, the speed is in the range 50 - 700 r p m

Referring now to Fig 2, the layout of the illustrated sorting machine, referenced 110, is similar to machine 10, and thus portions of the machine 110 present in machine 10 (Figs 1A and 1 B), are indicated by the same reference numerals as in Figs 1A and 1 B, and are not described again specifically below Accordingly, machine 110 is described herein only in respect of the differences between it and machine 10

Machine 110 has a cup-shaped rotor 114 which defines a generally conical inward-facing particle acceleration surface, referenced 115, which is oriented at an acute angle β with respect to vertical axis 18 in the range 25-40° Rotor 1 14 is arranged beneath outlet 22 and is mounted for rotation about axis 18 such that incoming constituent particles of the particulate material, fed thereto via feeder outlet 22, are engaged by particle acceleration surface 115

Machine 110 employs an inward-facing rebound plate 71 16 which is arranged about axis 18 and between outlet 22 of feeder 12 and rotor 1 14 In the illustrated embodiment rebound plate 7116 defines a downward- and inward-facing, truncated conical, annular rebound surface 7117 The rotating acceleration surface 115 of rotor 114 accelerates the particles outwardly, as indicated by arrows 118, such that they impinge upon rebound surface 71 17, so as to be deflected along generally helical trajectories as indicated by arrows 120

Referring now to Figs 3A and 3B, it is seen that sorting machine 1 10 may further have an optional stationary deflector member 1 19 for reducing the number of compartments and thus the number of sorted fractions Deflector member 119 is typically a ring-shaped member having a truncated conical cross-sectional configuration (as seen in Fig 3A), and mounted about vertical axis 18, via a bushing 121 , so as to cover, by way of example only, the two intermediate compartments 50 and 52 As shown, deflector member 1 19 defines an inward-facing deflection surface 122 and an outward-facing deflection surface 124 Deflector member 119 is configured such that any particles falling onto inward-facing surface 122, and which, in the absence of the deflector member would have fallen into compartment 50, are deflected into innermost compartment 48 Furthermore any particles falling onto outward-facing surface 124, and which, in the absence of the deflector member would have fallen into compartment 52, are deflected into outermost compartment 54 It will be appreciated that, the optional use of deflector member 119, in reducing the number of compartments employed, reduces correspondingly the number of sorted fractions

Referπng now to Figs 4-7, there are seen particulate material sorting machines constructed in accordance with further embodiments of the invention, in which two-stage sorting is performed In particular, after one fraction has been separated in a first or upper stage of sorting, the remainder of the material passing through the upper stage is sorted again In certain cases, wherein highly accurate sorting is required, particularly of the more elastic fraction of the material, and where the differences in elastic properties between the more elastic and less elastic particles is relatively small, two-stage machines are particularly advantageous Most of the portions of the two-stage sorting machines shown and described below in conjunction with Figs 4-7 have corresponding portions in one or more of the embodiments of Fig 1A-3B, where required, these similar portions are indicated in Figs 4-7 by reference numerals which are the same as those used in Figs 1A-3C, but with the addition of a single digit prefix corresponding to the number of the drawing being described Accordingly all such portions of the machine in Fig 4 are indicated by numbers with the prefix "4" those of the machine in Fig 5 are indicated by number with the prefix "5", and so on

Referring now to Fig 4, there is provided a two-stage sorting machine, referenced generally 400, having a first or upper stage 402, and a second or lower stage 404

Upper stage 402 has a feeder, referenced generally 412, similar to feeder 12 (Figs 1A, 2 and 3A), and a first rotor 414, similar to rotor 14 (Fig 1) Upper stage 402 aiso has first collector apparatus 415, which includes a funnel-shaped member having a diameter which is predetermined so as to catch all particles accelerated by first rotor 414, except for the outermost fraction The outermost fraction is allowed to fall downward through lower stage 404 so as to be received in an appropriate compartment of second collector apparatus, referenced generally 416 Lower stage 404 has a second rotor 424, similar to rotor 414, and second collector apparatus 416, which is similar to collector apparatus 16 (Figs 1A-3C) and is thus not described again herein Referring now to Fig 5, there is provided a two-stage sorting machine, referenced generally 500, having a first or upper stage 502, and a second or lower stage 504

Upper stage 502 has a feeder, referenced generally 512, similar to feeder 12 (Figs 1A, 2 and 3A), and a first rotor 5114, similar to rotor 114 (Figs 2 and 3A), and a rebound plate 5116, similar to rebound plate 116 (Fig 3A) Upper stage 502 also has first collector apparatus 515, which includes a funnel-shaped member having a diameter which is predetermined so as to catch all particles accelerated by first rotor 5114 via rebound plate 5116, except for the outermost fraction The outermost fraction is allowed to fall downward through lower stage 504 so as to be received in an appropriate compartment of second collector apparatus, referenced generally 516 Lower stage 504 has a second rotor 514, similar to rotor 14 (Fig 1A), and second collector apparatus 516, which is similar to collector apparatus 16 (Figs 1A-3C) and is thus not described again herein

Referring now to Fig 6, there is provided a two-stage sorting machine, referenced generally 600, having a first or upper stage 602, and a second or lower stage 604

Upper stage 602 has a feeder, referenced generally 612, similar to feeder 12 (Figs 1A, 2 and 3A), a first rotor 614, similar to rotor 14 (Fig 1A) Upper stage 602 also has first collector apparatus 615, which includes a funnei-shaped member having a diameter which is predetermined so as to catch all particles accelerated by first rotor 614, except for the outermost fraction The outermost fraction is allowed to fall downward through lower stage 604 so as to be received in an appropriate compartment of second collector apparatus, referenced generally 616 Lower stage 604 has a first rotor 6114, similar to rotor 114 (Figs 2 and 3A), a rebound plate 61 16 similar to rebound plate 116 (Fig 3A), and second collector apparatus 616, which is similar to collector apparatus 16 (Figs 1A-3C) and is thus not described again herein

Referring now to Fig 7, there is provided a two-stage sorting machine, referenced generally 700, having a first or upper stage 702, and a second or lower stage 704

Upper stage 702 has a feeder, referenced generally 712, similar to feeder 12 (Figs 1A, 2 and 3A) a first rotor 7114, similar to rotor 114 (Figs 2 and 3A), and a rebound plate 7116 Rebound plate 7116 is arranged about axis 718 and between outlet 722 of feeder 712, and rotor 7114 As in the embodiment of Fig 2, rebound plate 7116 defines a downward- and inward-facing, truncated conical, annular rebound surface 7117. Upper stage 702 also has first collector apparatus 715, which includes a funnel-shaped member having a diameter which is predetermined so as to catch all particles accelerated by first rotor 7114 via rebound plate 7116, except for the outermost fraction. The outermost fraction is allowed to fall downward through lower stage 704 so as to be received in an appropriate compartment of second collector apparatus, referenced generally 716. Lower stage 704 has a second rotor 724, similar to rotor 14 (Fig. 1A), and second collector apparatus 716, which is similar to collector apparatus 16 (Figs. 1A-3C) and is thus not described again herein.

Reference is now made to Fig. 8, which shows collector apparatus, referenced generally 1016. The general construction of collector apparatus 1016 is similar to that of collector apparatus 16, shown and described above in conjunction with Figs. 1A-3B, and is thus not described again herein, except in terms of differences between apparatus 1016 and apparatus 16.

Referring now briefly to Fig. 9A, in order to prevent particles being sorted from bouncing on the floor portions 1058 of the compartments 48, 50, 52 and 54, a layer 1158 of an energy-absorbing, resilient, typically polymeric material, such as PVC, is placed on the floor portion 1058. It will thus be appreciated that, when particles impinge on the layer 1 158, much of the impact energy that might otherwise cause them to rebound into an adjacent compartment, is absorbed, thus ensuring that they remain in the correct compartment.

Referring now additionally to Figs. 9A and 9B, the rotating, boom-like spreader member 1060 has a plurality of downwardly extending elements 1062 for spreading particles accumulated in the various annular compartments 48, 50, 52 and 54 of the collector apparatus 1016. In order to overcome a possible electrostatic attraction between sorted particles and the floor layer 1158, each downwardly extending element 1062 is formed so as to scrape the floor layer 1158, thereby to prevent small particles from causing a possible jamming of the machine due to electrostatic attraction between the particles and the floor layer 1158.

In more detail, elements 1062 are each formed of a flexible plate member 1162, which may also be of a polymeric material such as PVC. Each plate member 1162 is fastened to a rigid mounting element 1262, which is itself attached resiliently to boom member 1060. As seen, a top edge 1362 of the plate member 1162 is spaced apart from inner end surfaces 1462 of slots 1562 formed in boom member 1060, by compression members 1563, such that mounting element 1262 and plate member 1162 are pushed resiliently away from boom member 1060. Accordingly, a bottom edge 1662 (Fig. 9A) of plate member 1162 is retained in compressive contact with floor layer 1158, ensuring that, as the boom member 1060 is rotated, the floor layer 1158 is always scraped substantially clean. This prevents small seeds, or other small particles of material being sorted, from becoming caught between the scraper element and the floor, which may cause a malfunction of the machine.

Referring now to Fig. 10, in accordance with a further embodiment of the invention, there is provided a computer-controlled flow regulator 1024. Flow regulator 1024 includes plug 26, shown and described above in conjunction with Fig. 1A, and which is not specifically described again herein. In the present embodiment, in place of the handle 38 (Fig. 1A) which is used to cause an axial translation of plug 26 along screw member 36, there is provided a motor 1038, of any suitable type. Preferably, there is also provided a proximity sensor 1040, such as, the shielded EV-112M sensor of the Kyence Corporation, of 1-3-4 Higashinakajima Higashiyodogawa-ku, Osaka 533, Japan, and a suitable controller or computer, referenced 1042. In operation, as an initial step, a desired opening size, defined herein by the annular dimension 'x,' is input manually into the computer or controller 1042, in accordance with a desired flow rate determined by the type of particulate material to be sorted. The motor 1038 is then operated by the controller 1042, while sensor 1040 is operative to sense, typically, a distance which is either equal to, or related to, the vertical distance 'y.' The motor will continue to operate so as to raise or lower plug 26, until the proximity sensor 1040 indicates that the selected distance y has been reached. The motor is then stopped, and sorting operations can begin.

While the sorting machine of the present invention is suited to the sorting of any suitable type of particulate material, a preferred use thereof is for the sorting of a single type of material, and, in particular, such materials as seeds, grain or other agricultural produce. As mentioned above, the machine of the present invention has been found to be particularly useful in sorting agricultural produce for seed purposes which, as known in the art, undergoes several stages of sorting between harvesting, and marketing as seed.

The known sorting stages following a stage of precleaning an 'admixture' of harvested seeds or grain or the like, are as follows:

1. sorting to remove debris and unripe seeds - this may be done by any suitable method known in the art.

2. pre-sowing sorting, according to mechanical integrity of seeds. 3 sorting according to predicted germination rate in the event that sample germination tests of a given batch is not in compliance with accepted agricultural standards

While the above sorting stages are known, per se, there does not exist in the art, to the knowledge of the present Inventor, a single machine which is capable of sorting a cleaned admixture in accordance with the parameters defined in sorting stages 2 and 3, above The present invention provides a sorting machine which has been found to be capable of performing sorting stages 2 and 3, for a wide vanety of agricultural seeds and grains, rapidly and reliably The present invention is further capable of sorting according to the humidity or the moisture content of the seeds

The following description, in accordance with Figs 11-15C, relates to results of tests performed using the machine of the present invention, in particular, in accordance with the embodiment shown and described above in conjunction with Figs 1A and 1 B Throughout the following description, the described fractions 1 , 2, 3 and 4, relate to the sorted material received in compartments 48, 50, 52 and 54 (Figs 1A and 1 B), respectively Accordingly, fraction 1 is that material which has the shortest trajectory in the sorting machine, falling closest to vertical axis 18, and fraction 4 is that material which has the longest trajectory in the sorting machine falling furthest away from axis 18

Referring now to Fig 11 , there is provided is a diagram showing the distribution of vetch grain sorted by the machine of the present invention, in accordance with grain humidity In particular, it is seen that fractions 3 and 4 have 12 4% and 8 6% humidity, and are thus considered sufficiently dry for use as seed Fraction 2, with a humidity of 14 9%, is considered to be slightly damp, and is to be dried, as known in the art, by use of an ambient air stream Fraction 1 , on the other hand, with a humidity of 16 2%, is considered very damp, and must be dried, also as known in the art, with warm air

Figs 12A-12D are graphs showing pea seeds sorted into different fractions by the machine of the invention in accordance with physical integrity of the seeds and showing also a correlation with humidity While the present graphs do not show a separation into fractions, as in Fig 11 , it is nonetheless seen that there is a clear correlation between the trajectory length (length of unloading device) and humidity of the seeds, for each type of mechanical integrity classification Table 1 below shows the distribution of rye grains by various elasticity associated parameters, showing a clear correlation between the percentage of germination of each sorted fraction, and that as the elasticity decreases, the germination rate decreases accordingly. It will also be recalled that the lowest humidity vetch seeds were shown, in Fig. 11 , to be concentrated in fraction 4, and that the humidity increased in inverse proportion to the elasticity of the seeds.

Table 1 SEPARATION OF RYE GRAINS BY ELASTICITY

This correlation between elasticity and germination rate is also borne out by the graph of Fig. 13, which shows plots of rebound distance or elasticity versus germination rate, both for unsorted and sorted batches of onion seeds and vetch seeds

Fig 14 is a graph showing time dependence of the germination of different sorted fractions of tomato seeds, and Figs 15A-15C are graphs similar to Fig 14, but showing results for each fraction when the machine is operated at different speeds, between 0 and 600 r.p.m.

It is clear from the above-described results, that the machine of the present invention is capable of reliably sorting various types of seed and grain in accordance with the above-described sorting stages

It has further been found that, the machine of the present invention can be used for sorting at very high volumetric rates, of at least 1 tonne per hour for humus, wheat, grain hops and the like, and of at least 0 5 tonne per hour for light seeds, such as vegetable seeds, including tomatoes, onions and the like

It will be appreciated by persons skilled in the art that the present invention is not limited to what has been particularly shown and described hereinabove rather, the scope of the present invention is limited solely by the claims, which follow APPENDIX

Table Showing Comparison of Germination Rates Received after Sorting by Prior Art and Invention, Respectively

The above table shows results performed for the Inventors by Hazera Ltd., Israel, in October 1996. The tests were conducted on equal quantities of the seed types listed in column 1. Equal quantities of seeds were sorted by a prior art method, (as described in the Background of the Invention,) and by the machine of the present invention, such as shown and described in conjunction with Figs. 1A, 1 B, 3A and 3B.

Column 2 lists the germination rate of the fraction separated by sorting in accordance with the prior art.

Column 3 lists the germination rate of the fraction separated by sorting in accordance with the invention, using a single module only, as seen in Figs. 1A, 1 B, 3A and 3B.

Column 4 shows the overall germination rate for the entire batch tested.

Accordingly, by way of example, it is seen that for the melon seeds tested, 32% were found to have a germination rate which, in the prior art, was 88%, but, when sorted by use of the present invention, was 98%. Similarly, for watermelon seeds, 51% were found to have a germination rate which, in the prior art, was 82%, but, when sorted by use of the present invention, was 88%.

The above test results clearly illustrate that the machine of the present invention is significantly more reliable than the prior art in sorting seeds into batches which have a significantly greater likelihood of germinating, than prior art methods.

Claims

1 A machine for sorting particulate material comprising feed means for providing a continuous feed of particulate material, and having an inlet and an outlet, rotor means arranged beneath said outlet and mounted for rotation about a vertical axis so as to accelerate incoming constituent particles of the particulate material fed thereto via said outlet of said feed means, in directions outward relative to said vertical axis, along helical trajectories whose respective radial distances from said vertical axis at different elevations generally correspond to preselected physical properties of the particles, wherein the particles are subsequently allowed to fall generally downwards, means for rotating said rotor means at a rotational speed preselected in accordance with the type of particulate material sought to be separated, and collector means for dividing the falling particles into groups each having different characteristic properties

2 A machine according to claim 1 , wherein said rotor means has a generally conical outward-facing particle acceleration surface which defines a predetermined acute angle with respect to said vertical axis

3 A machine according to claim 1 , wherein said machine also comprises an annular plate member arranged about said vertical axis and vertically above said rotor means, and wherein said plate member is positioned such that the accelerated particles impinge thereupon so as to be rebounded therefrom in generally helical outward and downward directions

4 A machine according to claim 3, wherein said rotor means has a generally cup shaped configuration and defines a side wall having a generally upward-and inward-facing particle acceleration surface which defines a predetermined acute angle with respect to said vertical axis

5 A machine according to any of the preceding claims, and wherein said outlet of said feed means is arranged to permit a continuous supply of the particulate material to said rotor means under the influence of gravity, and said outlet is generally circular in cross-section and is arranged symmetrically about said vertical axis, thereby to permit a 360° distribution of supplied particulate material

6 A machine according to claim 5, wherein said feed means comprises means for adjusting the size of the opening of said outlet through which the particulate material is supplied to said rotor means

7 A machine according to claim 6, wherein said means for adjusting comprises a predetermined one of manually operated adjustment means, and computer-controlled adjustment means

8 A machine according to claim 1 , and wherein said collector means comprises a plurality of generally annular, concentric, trough-like compartments, separated by a corresponding plurality of dividing elements, each arranged at a predetermined radial distance from said vertical axis, such that each compartment defined therebetween receives a plurality of falling particles each having similar physical characteristics

9 A machine according to claim 7, and also comprising stationary deflector means arranged symmetrically about said vertical axis and arranged above said collector means, for intercepting falling particles and for deflecting them into adjacent compartments

10 A machine according to claim 9, wherein said stationary deflector means comprises a ring-shaped member having a truncated conical cross-sectional configuration, and arranged so as to so t least partially mask at least a predetermined one of said compartments, thereby to deflect particles that would otherwise have fallen into said at least one compartment, into a predetermined adjacent compartment

11 A machine according to claim 7, wherein said machine comprises at least first and second sorting stages arranged along said vertical axis, said rotor means is first rotor means located in said first stage, and said collector means compnses said plurality of generally annular, concentric compartments located in said second stage, and an additional, generally cone-shaped member, arranged symmetrically about said vertical axis beneath said first rotor means, and having an outlet, for receiving 0

particles falling within a predetermined radial area about said vertical axis and for providing them to said outlet, wherein said machine further comprises second rotor means located along said vertical axis in said second stage, between said outlet of said cone-shaped compartment and said collector means, and wherein said second rotor means is mounted for rotation about said vertical axis so as to accelerate incoming constituent particles of the particulate material, fed thereto via said outlet of said cone-shaped compartment, in outward directions along helical trajectories whose respective radial distances from said vertical axis at different elevations correspond to preselected physical properties of the particles, wherein the particles are subsequently allowed to fall generally downwards, thereby to further sort the particulate material.

12. A machine according to claim 7, and wherein each said compartment has a floor portion on which falling particles impinge, thereafter coming to rest.

13. A machine according to claim 12, wherein said floor portion comprises a resilient layer which is operative to partially absorb impact energy of particles impinging thereof, thereby reducing rebound of these particles after impinging on said resilient layer.