GB2090715A - Apparatus for separating grain - Google Patents

Abstract

Apparatus for separating grain from a mixture of grain and straw comprising a conveyor (3) capable of conveying a mixture of grain and straw in a generally horizontal direction to a discharge end thereof, and grain collecting means (4,5) located beyond the end of, and below the, conveyor (3) to collect grain that falls from the straw as it is discharged from the conveyor, characterised in that a plurality of elongate elements (49) are spaced laterally across, and project rearwards and downwards beyond, the discharge end of the conveyor (3) above the grain collecting means (4,5) so as to support straw. Preferably, the conveyor comprises straw walkers (3) and the elements (49) are wire fingers that are clamped to the end of the straw walkers. <IMAGE>

Description

SPECIFICATION Apparatus for separating grain This invention relates to apparatus for separating grain from a mixture of grain and straw.

In our British Patent No. 1101 431 we proposed apparatus comprising a conveyor capable of conveying a mixture of grain and straw in a generally horizontal direction to a discharge end, and a chute arranged so that said mixture discharged from the conveyor falls onto the chute. The chute has a floor that is imperforate to the passage of grain through it and is downwardly inclined and projects beyond said discharge end in the feeding direction of the conveyor. A trough covered by a grille is provided at or adjacent to the lower end of the chute, and is adapted so that when the mixture of grain and straw passes down the chute, grain is collected by the trough and straw passes over it. A rotor may be provided above and adjacent the rear end of the chute and is driven so as to assist the discharge of material from the apparatus.

It has been found that this known apparatus increases the efficiency of a combine harvester by increasing the amount of grain separated from the straw. In particular, loosening ofthe straw as it falls from the conveyor releases grain from the straw, and it is this grain, that would otherwise be lost, that is collected.

An object of the present invention is to further improve the separating action of this known grain separating apparatus.

This object is achieved according to the invention by providing a straw support structure that projects rearwards and downwards beyond the discharge end of the conveyor above grain collecting means so as to support discharged straw. The straw support structure therefore serves to support the straw momentarily as it passes off the end of the conveyor and allows the release of loose grain as the straw begins to fall. The downwards inclination of the straw support structure initiates falling of the straw so that grain can more easily separate from it before it finally falls freely.

Preferably, the conveyor is of the type known as straw walkers comprising a number of longitudinally extending members that are provided with crop engaging formations along their upper edges and are oscillated longitudinally to move crop rearwards along their length. The straw support structure comprises elongate elements that are spaced across the project from the end of each straw walker so as to move with the straw walker and loosen the straw before it falls.

It will be appreciated that the invention is applicable to any grain separating apparatus including a conveyor from which straw falls, and means to collect grain that is released from the falling straw.

The invention will now be described by way of example with reference to the accompanying drawings in which: Figure 1 is a side elevation of a combine harvester fitted with grain recovering apparatus according to the invention, Figure 2 is a rear view of the apparatus of Figure 1, Figure 3 is an elevation of the opposite side of the combine harvester to that shown in Figure 1, and Figure 4 is a longitudinal section through the end of a straw walker in Figures 1 and 2.

The drawings show the rear housing 1 of a combine harvester containing a straw walker mechanism 2 that receives crop from a crop threshing mechanism (not shown) and feeds it rearwards. Loose grain in the threshed crop material falls through the straw walkers 3 and is passed to a grain cleaning mechanism (not shown) while the straw passes over the end of the straw walkers 3 into a further grain separating mechanism comprising a chute 4 leading down to a trough 5 covered by a wire comb 6, and a rotor 7 provided adjacent the rear end of the chute 4. The straw falls onto the chute 4 and passes down over the wire comb 6 and is fed out of the housing 1 with the aid of the rotor 7 that is driven counterclockwise as seen in Figure 1.As the straw falls, loose grain is further released from the straw and passes through the comb 6 into the trough from where it is removed by a cross auger 8 and passes via a paddle elevator 9 to the grain cleaning mechanism.

The rotor 7 is carried between the lower ends of a pair of downwardly extending arms 10 that are pivotally connected to the housing 1 at their upper ends so as to allow the rotor to be swung backwards and forwards about the axis of shaft 11 between a number of different settings. Figure 1 shows the rotor in full lines in its forwardmost setting and in broken lines in its rearmost setting and intermediate settings.

An important function of the rotor isto ensure a uniform thickness of the material fed over the comb 6. Adjustment of the setting of the rotor relative to the comb allows this thickness to be adjusted for maximum grain separation as well as for crop bulk to avoid blockages.

A rotor adjustment arm 12 is connected to each end of shaft 11 on the outside of the housing side wall 17. The adjustment arm 12 extends downwards alongside the adjacent rotor support arm 10 and carries a handle 13 at its lower end by which the arms 10 and rotor 7 can be swung backwards and forwards to any desired setting. A releasable fastener 14 in the form of a screw is provided to secure the rotor in each of its settings, the screw 14 being inserted through an aperture 15 in the adjustment arm, one of a number of selected apertures 16 in the side wall 17 of the housing and engaging a nut 18 secured to the rotor support arm 10.

The rotor drive mechanism comprises a V-belt pulley 19 that is concentric with the shaft 11 and is supported by a bearing 20 connected through bolts 21 to the adjustment arm 12.

A V-belt pulley 22 is similarly supported at the lower end of the adjustment arm by a bearing 23 and a V-belt 24 couples both pulleys 19,22 and is tensioned by a pulley 25 that is adjustably supported in a slotted guide 26 connected to the adjustment arm l2betweenthetwopulleysl9,22.

A tubular spindle 27 is insertablethrough the lower pulley 22, and apertures in the adjustment arm 12, side wall 17 and rotor support arm 10, and is engageable over a drive spigot 28 on the end. of the shaft 29 of the rotor. The spigot 28 is shaped to key with the spindle 27, and a shaped head 30 on the spindle keys between lugs 31 provided on the pulley 22. A screw 32 is insertablethrough the spindle 27 and engages a threaded hole 33 in the spigot 28 to retain the spindle in place.

Figure 3 of the drawings is a side elevation showing the V-belt 24 passing over the pulleys 19,22 and past the tensioner pulley 25. It also shows the input drive belt 34 that drives the upper pulley 19 and a pulley 35 connected to the grain collecting auger 8 and the elevator 9 associated with the grain collecting chute 5. The main drive pulley 36 is driven from the crankshaft 37 that operates the straw walkers 2.

A crop deflector arrangement is provided within the housing 1 above the rotor 7 so as to deflect crop downwards to the rotor and prevent it from passing out of the combine over the top of the rotor. This deflector arrangement is made adjustable to accommodate the different settings of the rotor and to feed crop to the rotor in each case. As shown in Figure 1, an upper fixed baffle 38 is provided that extends downwards and rearwards from the top of the housing, and two relatively foldable baffles 39 and 40 are provided between the fixed baffle 38 and the rear wall 41 of the housing. The upper baffle 39 is located so as to pivot and slide relative to the lower edge of the fixed baffle 38, and the lower baffle 40 is pivoted about a transverse axis 42 adjacent the lower edge of the wall 41.A tension sprng 43 holds these two baffles 39 and 40 in pivoting sliding engagement at 44 as they move between different settings corresponding to those of the rotor.

The baffle 39 is formed in three relatively angled sections 39,39" and 39" so that the lower sections 39", 39"' form a construction above the rotor in all of its settings. The upper section 39' lies above and behind the guide 38 in the forwardmost setting, and moves downwards and pivots rearwards to the rearmost setting. The lower baffle 40 simply swings rearwards towards the rear wall 41.

The straw walkers 3 are of substantially conventional construction and each comprise a pair of rearwardly extending vertical plates 45 arranged alongside one another and connected by a sieve plate and lower grain collecting floor. The upper edges of the vertical plates 45 are formed with a series of steps that rise gradually rearwards and then drop sharply.

A saw tooth is formed along the rising edges. The saw tooth edges and drops in the steps engage the underside of the crop and feed it rearwards as the straw walkers are oscillated longitudinally by the action of the crank drive mechanism 37 on which the straw walkers are mounted.

The action of the straw in falling from the ends of the straw walkers 3 aids the release of threshed grain from the straw, this grain being collected in the trough 5. In order to further assist release of the threshed grain from the straw, a plurality of elongate elements 49 such as wire fingers are provided that are spaced laterally across the end of each straw walker 3 and project rearwards beyond the end of the straw walkers above the chute 4. Preferably, these fingers 49 are inclined downwards, at least over their end portions 50. These fingers 49 tend to cause additional loosening of the straw before it falls freely, and thereby assists release of the grain.

In an alternative embodiment of the invention the rotor 7 may be fixed relative to the chute 4 as shown in the British Patent No. 101 431. In yet another embodiment the rotor 7 could be omitted altogether.

Claims (9)

1. Apparatus for separating grain from a mixture of grain and straw comprising a conveyor capable of conveying a mixture of grain and straw in a generally horizontal direction to a discharge end thereof, grain collecting means located beyond the end, and below the conveyor to collect grain that falls from the straw as it is discharged from the conveyor, and a straw support structure projecting rearwards and downwards beyond the discharge end of the conveyor above the grain collecting means so as to support straw as it is discharged.

2. Apparatus as claimed in claim 1 in which the straw support structure comprises a plurality of elongate elements that are spaced lateraliy across and project rearwards beyond the discharge end of the conveyor.

3. Apparatus as claimed in claim 2 in which the conveyor oscillates longitudinally and the elongate elements are connected to the discharge end of the conveyor so as to oscillate with it.

4. Apparatus as claimed in claim 2 or 3 in which the elongate elements are rod-shaped and are clamped to the end of the conveyor.

5. Apparatus as claimed in claim 4 in which the conveyor comprises a straw walker and the elongate elements are clamped to the end wall of the straw walker by a single clamp plate.

6. Apparatus as claimed in claim 5 in which the clamp plate is of channel section and has a clamp portion and a support portion each formed with an aperture therein, through which a respective elongate element projects so that it is supported at two spaced apart points along its length.

7. Apparatus as claimed in any one of claims 4to 6 in which each elongate element is formed with an end portion by which it is clamped in place and a projecting portion that extends at an angle to said end portion.

8. Apparatus as claimed in any one of the preceding claims in which the grain collecting means comprises a rearwardly and downwardly inclined grain chute with a trough at its lower end covered by a grille.

9. Apparatus for separating grain from a mixture of grain and straw substantially as herein described with reference to the accompanying drawings.