GB2135913A

GB2135913A - Sorting method and machine

Info

Publication number: GB2135913A
Application number: GB08405735A
Authority: GB
Inventors: Roger Selly
Original assignee: Individual
Current assignee: Individual
Priority date: 1983-03-03
Filing date: 1984-03-05
Publication date: 1984-09-12
Also published as: GB2135913B; GB8405735D0

Abstract

The sorting (separating) of small objects, such as grain, from lighter contaminants, such as chaff, is effected by the simultaneous action of centrifugal force and a current of air. A machine for carrying out this sorting comprises a rotatable truncated cone (2), a distributor (3) for flinging the mixture to be sorted on to the inner surface of the cone, and means (17) for producing a current of air moving against the centrifugal force imparted by the rotation of the cone. The mixture to be sorted may be fed on to the distributor (3) via a cyclone (12). <IMAGE>

Description

SPECIFICATION Sorting method and machine The present invention relates to a method of sorting (separating) small objects such as grain from lighter contaminants such as chaff, and to a machine for carrying out the said mattered.

In the separation of grain from the chaff which comes with it when the corn is threshed, the traditional method (winnowing) is to toss the mixture up in a cross wind. The denser grain is relatively unaffected by the cross wind, but the chaff is blown away. In the modern combine harvester the separation is effected by sieves, but difficulties are experienced because the rather coarse methods of threshing used in the machine produce bits of straw which can clog up the sieves, especially if overloaded.

In the present invention a sorting (separation) of small objects, such as grain, from lighter contaminants, such as chaff is achieved by the simultaneous action of a centrifugal force and a current of air (which way be termed a wind). The centrifugal force may be applied to the mixture to be separated to bring it into contact with the inner surface of a rotating cone.

The advantages of the present invention are: i) both the centrigufal force and the wind force may be adjusted to achieve the desired separation of the components of the mixture; ii) the adjustments in (i) may be performed whilst the separation process is in operation; iii) the forces responsible for separating the mixture (i.e. the centrifugal force and the wind force) may be increased in strength to create larger differentials of force acting on dissimilar particles, which will increase the power of the technique to resolve (separate) mixtures.

According to the present invention such a method comprises feeding the mixture to be sorted on to a rotating surface such as the inner surface of a truncated cone having its wider end upwards and its axis of symmetry vertical, about which it rotates; causing a current of air to pass downwards through the cone; and causing said cone to rotate about its axis of symmetry at such a speed that the heavier objects move upwards and over the upper rim of the cone, while the lighter contaminants are blown downwards through the lower end of the cone.

The invention further provides apparatus for carrying out the said method and comprising a truncated cone mounted to rotate about its axis of symmetry with its wider end upwards, means for rotating said cone, means for feeding the mixture to be sorted on to the inner surface of the cone, means for causing a current of air to pass downwards through the cone and means for collecting these sorted objects as they passed over the rim of the cone. They inner surface of the cone may be roughened or provided with ridges or indentations so that motion is more readily imparted to the objects being sorted.

The cone surface may be solid or it may include perforations; such perforations would be designed solely to permit the passage of air, not as a means of separating objects of different size by screening.

Stationary or rotating baffles may be positioned inside the rotating cone to direct the air current used in the separation process, as is found desirable in any particular case.

The feeding of the material to be sorted on to the surface of the cone may be carried out by a distributor so constructed as to give the material a motion in the direction of movement of the cone surface. For this purpose a rotating disc is suitable.

The cone angle and its speed of rotation as well as the strength of the air current downwards will depend on the size and weight of the objects and the contaminants. To separate wheat, barley or oats from the chaff produced in a combine harvester a cone angle of about 90" is found suitable. The apparatus is designed to accept and sort in situ the grain gathering of a combine harvester, to replace the sieves such as are used at present.

The invention will now be described with reference to the accompanying drawings in which Figure 1 shows diagrammatically one device according to the present plan; Figures 2 and 3 show in side section and in plan view (the latter being partly cut away to show certain details) a preferred device according to the present invention.

Referring to Figure 1 of the drawings, on a shaft 1 which in operation is driven from the engine of the combine harvester on which the device is mounted, is an inverted cone 2 and a distributor 3. Both of these members rotate with the shaft 1, the cone 2 being tied to the distributor 3 by struts 10. Afan 4 mounted freely on the shaft 1 is driven independently of the rotation of the shaft 1 by a pulley 5 driven from the engine, the drive being provided with means not shown whereby the air curent produces by the fan can be varied by varying its speed of rotation. The material to be sorted is fed to the centre of the distributor 3 by a screw feed 6. Fixed baffles 7, 8 and 9 keep the flow of materials in the desired paths.

In operation, a mixture of chaff and grain, for example, is fed by the screw feed 6 on to the distributor 3 from which, by the rotation of the latter, it is flung outwards on to the inner surface of the cone 2. Here the centrifugal force which the rotation of the cone imparts to the grains causes them to move upwards and outwards and thus go over the upper rim of the cone where they are collected. On the other hand the chaff does not so easily take up this centrifugal force but is more readily taken up by the stream of air from the fan which blows the chaff downwards and through the bottom of the cone.

The precise details of the mechanical construction necessary to put into practical effect the device shown schematically in the Figure will be readily apparent to those skilled in the art.

Within the apparatus, material moving towards the narrower end experiences a diminishing centrifugal force and conversely material moving towards the wider part experiences an increasing centrifugal force. The apparatus may require some means, such as the provision of indentations on the inner surface of the separating cone, to prevent conservation of the angular momentum or particles during separation (conservation would impede movement of the particles to a new orbit of rotation by causing a reduction in angular velocity to accompany an increase in radius of rotation and vice versa).

In a preferred embodiment of the invention shown in Figures 2 and 3, the shaft 1 carries the distributor 2, provided with vanes 16, and the cone 3 is driven to rotate therewith by being tied to it by struts 10. The mixture to be separated is blown in by force through pipe 11 to a cyclone 12. The cyclone, a well known device for separating dust and other light material from air, causes the air to pass upwards in the direction of the arrows and through the outlet 23, while the solids fall down on to the distributor 3 and thence they are flung on to the cone 2.

A paddle fan 17, also mounted on the shaft 1, sucks air through holes 19 in the fixed casing 18, and holes 20 in the upper part of the rotating cone 3. The holes 19, 20 are made small enough to prevent passage of grains through them. The current of air created by the paddle fan 17 carries the chaff towards the narrow end of the rotating cone 3 and thence out of the machine by outlet 23. The grain meanwhile travels up the inner surface of the rotating cone 3, passes over the air inlet holes 20, and is flung off the top edge of the cone. Rotating paddles 22, fixed to the rotating cone 3, draw air from the inlet holes 19, 20 and create a current of air that carries grain out of the machine through outlet 13.

Seals 14 between the rotating cone 3 and the fixed casing 18 prevent air escaping or entering at these points. To direct the current of air through the intake holes 20, a number of fixed baffles 15, may be arranged around the outside of the rotating cone 3.

Afan could be mounted on shaft 1 to provide suction at the cyclone outlet 23, so that the mixture to be sorted would be sucked, rather than blown, into the machine via inlet 11. Material leaving the distributor 3 could be directed upwards or downwards by incorporating a lip around the edge of the distributor 3.

In both embodiments of the invention the rotating member providing the centrifugal force need not be a true cone but could have the shape of revolution of a curve instead of a straight lin as in a true cone.

The distributor, instead of being mounted directly on the shaft 1 so that it rotates at the same speed as the rotating member providing the centrifugal force, may be mounted on a sleeve coaxial with the main shaft 1 and drivably connected to it through gearing to cause it to rotate more slowly or faster than the main shaft.

Claims

1. A method of sorting small objects such as grain from lighter.contaimenants such as chaff, characterised by feeding the mixture to be sorted on to a rotating surface such as the inner surface of a truncated cone having its wider end upwards and its axis of symmetry vertical, about which it rotates; causing a current of air to pass downwards through the cone, and causing said cone to rotate about its axis of symmetry at such a speed that the heavier objects move upwards and over the upper rim of the cone, while the lighter contaminants are blow downwards through the lower end of the cone.

2. A method as claimed in claim 1 characterised in that the said mixture is fed on to the cone by means of a rotating disc.

3. A method as claimed in claim 1 or 2 characterised in that the current of air is produced by blowing in air from above.

4. A method as claimed in claim 1 or 2 wherein that current of air is produced by drawing air from below.

5. Apparatus for sorting small objects such as grain from lighter contaminants such as chaff, said apparatus comprising a truncated cone mounted to rotate about its axis of symmetry with its wider end upwards, means for rotating said cone, means for feeding the mixture to be sorted on to the inner surface of the cone, means for blowing a current of air downwards through the cone and means for collecting the sorted objects as they pass over the upper rim of the cone.

6. Apparatus as claimed in claim 5 characterised by the provision of a cyclone for separating the incoming mixture to be sorted from the air bringing it in to the apparatus.

7. Apparatus as claimed in claim 5 or 6 wherein the said means for feeding the mixture comprise a rotating disc.

8. Apparatus as claimed in any of claims 5 to 7, characterised in that curent of air there are provided means for blowing in air from above.

9. Apparatus as claimed in any of claims 5 to 7, characterised in that there are provided means for drawing air from below.