WO2001001753A1

WO2001001753A1 - Stripper front

Info

Publication number: WO2001001753A1
Application number: PCT/AU2000/000798
Authority: WO
Inventors: Robert W. Taylor
Original assignee: QAS WHOLESALERS Pty Ltd
Current assignee: QAS WHOLESALERS Pty Ltd
Priority date: 1999-06-30
Filing date: 2000-06-30
Publication date: 2001-01-11
Anticipated expiration: 2001-12-30
Also published as: AUPQ129099A0

Abstract

A harvester front (1) includes an elongate drum (2) mounted for rotation about an axis generally transverse to the direction of travel of the harvester. The drum (2) has a plurality of crop-engaging teeth (3) distributed across and around the drum (2). A cowl (10) at least partially surrounds the drum (2) on a leading side (11) and defines an inlet (12) disposed forward and adjacent the drum (2). A flow of air is induced from the rotation of the drum (2) and contained within the cowl (10) to establish a flow of air through the inlet (12) from the area forward of the drum (2).

Description

STRIPPER FRONT

Field of the Invention

This invention relates to the mechanical harvesting of crops. Mechanical harvesters are used for harvest of a wide variety of cereal and legume crops, including traditional grain crops such as wheat, oats, barley and rice, as well as more brittle crops such as peas. This invention is particularly concerned with the devices known as "fronts" that are fitted to mechanical harvesters to harvest the desired portion of the crop which may contain a greater or lesser amount of undesired material.

Background Art

Crude mechanical harvesters have been thought to have been used as early as Roman times. However it was not until the mid eighteenth century in England that the forerunners to current mechanical harvesting machines were proposed. This lead to the grant of the first patent on a reaping machine in England in 1799. In Australia the first development of mechanical harvesters took place in the 1840s and led to the development of a stripper comb and rotary beater principle which was widely used for a century in cereal harvesting in Australia. The Australian harvesters were distinguished from the European and American devices which used cutter bars to take in the whole crop. The Australian strippers basically used fixed steel combing teeth with a rotary beater that forced the crop into the teeth. Whilst these harvesters were eminently suitable for Australian cereal crops they were found not to be suitable for tangled, weedy or green crops or for use in crops such as rice. The mid 1980s saw the development of the first so called grain stripping fronts for mechanical harvesters. These devices differed significantly from known harvesters by utilising the concept of upwardly combing teeth mounted across the front of the harvester. The development that led to the commercial introduction of this type of stripper front for harvesters was the invention of flexible "keyhole" shaped stripping elements. The stripper front is based on the concept of stripping the crop seed from the plant whilst leaving the stalks or other material standing in the field. The typical configuration of the stripper front includes an inlet cone or nose that pushes the crop slightly forward ahead of the tooth carrying drum which rotates in a forward and upward direction relative to the direction of travel of the harvester. Harvesters of this type and the teeth used on the stripper drums are described for example in GB Patent Application 2176685, International Patent Application WO 88/05626, International Patent Application WO 92/08339 and International Patent Application WO 92/0337

These so called stripper fronts have been commercially successful and are in widespread use. They offer significant reduction in the amount of unwanted material that is harvested with the grain or the like as well as at least partially threshing the grain so that very little straw is taken into the harvester for separation.

Despite these advantages the stripper fronts still share a disadvantage with traditional knife fronts. In both cases the mechanical contact with the crop can cause the grain and even complete grain heads to be dislodged from the crop prior to collection. That is, the grain is thrown forward of the harvester and falls on the ground under the influence of gravity. It has been estimated that commonly 10% or more of product can be lost in this manner depending upon the type of crop and its condition at the time of harvesting.

It is also desirable where possible to reduce the power consumption of mechanical harvesters so that the overall cost of harvesting can be reduced. Driving the stripper front represents a considerable amount of the power consumption of the harvester. Additionally the efficiency of the harvester is related to the amount of undesired material that is processed through the harvester during the course of extracting the desired product. The amount of processing required to extract the desired product can also have an impact on the quality because of the possibility of smashing, cracking and bruising where extensive processing is required. Disclosure of the Invention

It is an object of this invention to provide an improved stripper front for use with a mechanical harvester that will overcome, or at least ameliorate, one or more of the foregoing shortcomings.

Accordingly, in one aspect this invention provides a harvester front for use with a mechanical harvester, including an elongate drum mounted for rotation about an axis generally transverse to the direction of travel of the harvester, said drum including a plurality of crop-engaging teeth distributed across and around the drum, a cowl at least partially surrounding the drum on a leading side and defining an inlet disposed forward and adjacent the drum, means associated with a trailing side of said drum to contain a flow of air within the cowl and means to induce from the rotation of said drum a flow of air through said inlet from the area forward of the drum.

Various drum orientations are possible. For example, the drum can be arranged horizontally and extend perpendicular to the direction of travel in the generally traditional configuration. In other configurations, multiple drums can be used arranged horizontally in V-shaped orientations or multiple vertical drums can be used.

The air flow from adjacent the forward side of the drum where the teeth or fingers first contact the crop results in the entrainment of any dislodged material in the air flow so that it is carried into the stripper front.

The teeth or fingers have a two-fold function. They generate the air flow and also effect the stripping of the crop. The teeth are preferably arranged in rows extending across the drum, or in other words in a direction generally parallel to the axis of rotation. In a further preferred form of the invention the teeth or fingers are arranged in rows that extend helically around the drum. This results in the fingers across the drum sequentially engaging the crop as opposed to a conventional straight line of fingers which simultaneously engage the crop. This helical arrangement of the teeth or fingers has been found to significantly reduce the power consumption and smooth the operation of the front. This is because a relatively smooth continuous power is required as each portion of each helix sequentially engages the crop as distinct from the pulsed power requirements of linear parallel rotating rows. Additionally, the helical arrangement results in a smoother feeding of the material through the harvester so that the subsequent mechanical handling is at a smoother continuous level, rather than being pulsed due to the pulsed input of the crop from the front. In the preferred embodiment the actual width of crop across the front that is in contact with the fingers is typically one to 1.5 metres across a drum of the order of 12 metres in width.

The teeth or fingers are preferably formed from a relatively rigid material and are bent along their length so that the free ends project forwardly in the direction of rotation. The fingers are preferably formed by two straight sections that meet at the bend. The angle of the bend is preferably about 30E. In the currently preferred embodiment teeth of the kind having a keyhole shaped cut-out between the fingers are used and the bend is preferably located at about the centre of the rounded portion of the keyhole. The bent tooth arrangement has been found to provide improved performance thought to result from the grain or grain heads being "cradled" during the upward movement of the fingers to more effectively strip the grain from all sides of the stem. The preferred form of the fingers also generates a higher air flow volume and velocity which improves the capture of grain and the separation of grain from MOG.

The fingers are preferably mounted to the drum via a hinged connection. The hinged connection includes a stop against which the fingers bear under centrifugal force resulting from rotation of the drum. This corresponds to the normal operating orientation of the fingers. The hinged connection allows the fingers to be displaced if they strike a foreign object such as a stick or rock. In this way damage to the fingers is reduced. The hinged connection is configured so that the paths over which the fingers move result in the ends being at the greatest radial distance from the drum when the fingers are against the stops in the operating position. The stops can include a cushion of resilient material, such as rubber, to prevent chatter of the fingers. In order to accommodate the helical arrangement of the fingers the hinged connection is preferably in the form of a number of discrete sections along the length of the row of fingers.

The grain dislodged by the action of the fingers is also entrained in the air flow through the cowl. Preferably the speed of the air flow is rapidly reduced in an expansion chamber defined by the cowl. A soft curtain is preferably provided following the expansion chamber to direct impacting grain onto a transporting medium such as a conveyor belt. The conveyor belt transports the grain via a feeder/beater to the feeder house of the harvesting machine.

The air flow from the expansion chamber can be changed in direction prior to impacting the curtain to improve separation of the entrained grain and MOG. This is preferably achieved by strategically placed directing means such as separation walls and turning vanes. The air flow direction is changed which results in the path length of the air flow being increased which allows greater time for deceleration of the flow. The changes in direction are preferably achieved using a series of spaced vanes that project from the cowl into the airflow. The vanes are preferably angled at about 45E to the incident air flow. The vanes are preferably arranged in opposed banks so that the flow is directed toward a central region. As a result more of the grain is directed to the central region of the curtain and subsequently to the region of the centrally located feeder/beater which directs the grain to the feeder house of the harvester. This reduces the loading on the cross feeding conveyors. The opposed banks of vanes also result in a pressure increase in the central region of the air flow. Consequently, the downstream air flow tends to diverge so that a large change in airflow direction is achieved due to the vanes and subsequent pressure equalisation. By the use of suitable geometry, this direction change is used to separate the heavier grain from MOG which remains in the air flow and is carried out the exhaust.

It has been found that the traditional combing action of the stripper fingers combined with the directing of the air flow carrying the harvested material described above is highly effective in separating the grain from material other than grain (known in the industry as MOG).

The exhaust air flow carries with it much of the dust and light MOG. This further reduces the amount of processing the harvesting machine itself is required to do and thus further reduces power consumption to provide corresponding reduction in fuel used and improved productivity.

Preferably, air is prevented from exiting the expansion chamber adjacent the fingers on the drum by a second set of correspondingly shaped air control fingers. The air control fingers are preferably stationary fingers extending across the width of the drum having apertures corresponding to the shape and size of the fingers mounted on the drum.

Preferably, a shroud extends beyond the air control fingers to define a rear opening in the stripper front adjacent the trailing side of the drum. The shroud adjacent the rear opening is preferably arranged so as to direct the air flow generated by the movement of the fingers from the position of the air control fingers to the end of the cowl forward of the rear opening. In a preferred configuration, a series of air outlets can be formed along the edge of the shroud to control the direction of the air flow. This flow from the rear of the opening is used to agitate grain so that it is entrained in the air flow to the inlet opening of the front. In practice, by directing this flow from the rear opening at least partially toward the ground it is possible to recover grain that has fallen to the ground that would otherwise be completely lost. Preferably, the feeder/beater of this invention is in the form of a cylindrical drum with frusto-conical end sections. The drum is mounted for rotation about an axis normally transverse to the stripper front. A feeder/beater drum is positioned centrally below the impact curtain described above. Cross feed conveyors are positioned on either side of the feeder/beater drum to feed material from the outer regions to the centre. The frusto-conical ends of the drum allow the conveyors to be directed toward the central axis of the feeder/beater drum rather than to the front of the drum as in the case of prior art feeder/beater drums. This is of particular advantage because it allows the drum to be located relatively further forward thus reducing the overall width of the stripper front. The overall width is an important consideration because of the weight of the stripper front and the load imposed on the mountings with the harvester. The feeder/beater drum is provided with transversely extending beaters extending outwardly from the surface. These can be in the form of resilient flaps and may be somewhat inclined to the axis of rotation.

It is estimated that the stripper front of the present invention can provide a productivity gain over a conventional harvester of the order of 7.5%. In other words, an extra 7.5% of grain can be obtained from the crop with a 7.5% reduction in the cost of harvesting. Additionally, the grain suffers less bruising and cracking so that a better finished grade, and therefore higher sale price is obtained.

The stripper front of the present invention has application not only to large harvesters for broad acre applications but also to smaller operator-followed harvesters which are used for various crops and crop locations. Some applications of the small machines are for especially fragile crops for example the harvesting of vegetable seeds from onions, cauliflowers and the like.

Further, the effectiveness of the present invention in harvesting can make it possible in some crops to achieve a so-called double growth. That is, to allow a regrowth and subsequent harvesting of the crop following an initial harvesting. One embodiment of the invention will now be described, by way of example only, with reference to the accompanying drawings.

Brief Description of the Drawings

Figure 1 is a schematic cross section of a stripper front according to this invention;

Figure 1A shows the schematic cross section of Figure 1 with operational characteristics;

Figure 1B is a partly sectioned view of the stripper front shown in Figure 1 ; Figure 2 is a schematic plan view of the stripper front shown in Figure 1 ;

Figure 3 is a perspective view of a drum and tooth arrangement following part of the stripper front of Figure 1 ;

Figure 4 shows the engagement of the fingers shown in Figure 3 with air control fingers forming part of the arrangement shown in Figure 1 ; Figure 5 shows the fingers shown in Figure 3 as they pass air outlets associated with the rear opening of the stripper front shown in Figure 1 ;

Best Mode for Carrying out the Invention

The drawings show a stripper front 1 for use with a harvesting machine (not shown) of conventional type. The harvesting machine can essentially be of any type suitable to thresh the portions of a crop removed by the harvester front 1 to recover the desired product and separate it from waste. In the following description the desired product will be referred to as "grain" and the waste as "MOG" (material other than grain). Harvesters of this type all include provision usually through hydraulic pressure for the driving of the drums, conveyors and the like associated with stripper fronts.

The stripper front 1 includes a cylindrical drum 2 mounted for rotation about a generally horizontal axis transverse to the normal operational direction of movement of the front 1 (to the left as viewed in Figure 1). Drum 2 includes a number of rows of teeth or fingers 3 which extend generally parallel to the axis of rotation of drum 2. As best seen in for example Figures 3 or 4 the teeth have a generally triangular profile 4 with a "keyhole" 5 interposed at the base of each tooth 3. Teeth of this type are described in Australian Patent Specification 88663/91. Also as best seen in Figure 3 the teeth 3 are arranged in parallel rows 6 that extend helically around drum 2. The circumferential position of the ends 7,

8 of the rows 3 approximately correspond to the circumferential position of the ends 8, 7 of one of the adjacent rows 3. The drum 2 is mounted within a chamber

9 partially defined by a cowl 10. The cowl 10 extends from in front of the drum 2 to define a front edge 11 , of an inlet 12 that extends transversely across the stripper front 1. The cowl 10 includes a rounded nose portion 13 that gently displaces the crop (Figure 1A) downwardly with the passage of the stripper front 1. Chamber 9 opens into an expansion area 14 behind drum 2. a soft curtain 15 depends from cowl 10 into the expansion area 14. The soft curtain 15 can for example be formed by a piece of rubber plastics or the like. Directly below curtain 15 a pair of conveyors 16, 17 are positioned to convey grain transversely of the stripper front or in other words parallel to the axis of drum 2. The conveyors 16, 17 are disposed across the rear of the stripper front 1 and operate in opposite directions so as to carry material that falls onto the conveyors 16, 17 toward a centre aperture 18. a third conveyor 19 then moves the material rearwardly into the input region of the harvesting machine (not shown). It will be apparent that this conveyor mechanism 16, 17, 19 may be configured to suit the particular harvesting machine, a row 20 of stationary air control fingers 21 is mounted across the stripper front 1 at the rear of drum 2. These fingers are best seen in Figure 4. These fingers 21 are correspondingly shaped to the fingers 3 on the drum 2 so that the two sets of fingers 3, 21 intermesh as they pass. This is best seen also in Figure 4. The purpose of the air control fingers 21 is to prevent a substantial egress of air from chamber 9 around the rear side of drum 2. Rather, the bulk of the air flow is directed out of the rear of the stripper front 1 through vents 22 above conveyor 19. A shroud 23 is positioned below fingers 21 around the rear portion of drum 2. This shroud 23 directs an air flow induced in a region 24 behind the drum 2. a corrugated element 25 shown in Figure 5 is attached to the edge of the shroud 23 to direct the air flow exiting region 24 through outlets 26. It will be apparent that the corrugations 25 correspond to the spaces between teeth 3 as best seen in Figure 5. This air flow is directed so as to agitate grain (not shown) in the path of the stripper front 1. In practice this air flow is directed forwardly at about 45E so as to impinge the ground more or less directly below inlet 12.

In use the stripper front operates as follows. Drum 2 is rotated in the conventional manner in a clockwise direction as viewed in Figure 1. In addition to the action of the fingers 3 stripping grain from the crop in the traditional manner and directing it into chamber 4 the rotation of drum 2 with fingers 3 also generates a significant air flow into inlet 12 from the region immediately in front of the drum 2. This flow of air is directed into chamber 4 but is largely prevented from exiting the chamber 4 around the rear of drum 2 by the air control fingers 21. The bulk of the air flow is therefore directed through expansion chamber 14.

The flow of air from the area in front of drum 2 and adjacent rounded nose 13 results in any grain that is dislodged by contact with the nose 13 or fingers 3 being entrained in the air flow and carried into chamber 4. The entrained material which includes grain and MOG passes into expansion chamber 14 where it naturally decelerates due to the expanding volume. The heavier grain has a higher momentum and thus impacts curtain 15 and falls onto conveyors 16, 17. Most of the dust and lighter MOG remains entrained in the air flow and passes out of the rear vent 22. The grain and MOG that lands on conveyors 16, 17 is carried to conveyor 19 to the feed to the harvesting machine where it is processed in the known manner.

The flow of air generated by the passage of fingers 3 in the region 24 adjacent shroud 23 is directed by outlets 26 to the ground in the area immediately below inlet 12. This results in the agitation of grain on the ground or grain that is falling towards the ground. This significantly increases the amount of grain that is entrained in the flow of air to inlet 12.

Claims

CLAIMS:

1. A harvester front including an elongate drum mounted for rotation about an axis generally transverse to the direction of travel of the harvester, said drum including a plurality of crop-engaging teeth distributed across and around the drum, a cowl at least partially surrounding the drum on a leading side and defining an inlet disposed forward and adjacent the drum, means associated with a trailing side of said drum to contain a flow of air within the cowl and means to induce from the rotation of said drum a flow of air through said inlet from the area forward of the drum.

2. A harvester front wherein the drum is arranged horizontally and extends perpendicular to the direction of travel.

3. A harvester front as claimed in claim 1 or claim 2 wherein the teeth are arranged in rows extending across the drum.

4. A harvester front as claimed in claim 1 or claim 2 wherein the teeth or fingers are arranged in rows that extend helically around the drum.

5. A harvester front as claimed in any one of claims 1 to 4 wherein the teeth formed from a relatively rigid material and are bent along their length so that the free ends project forwardly in the direction of rotation.

6. A harvester front as claimed in claim 5 wherein the teeth are formed by two straight sections that meet at the bend.

7. A harvester front as claimed in claim 6 wherein the angle of the bend is about 30°.

8. A harvester front as claimed in claim 5 or claim 6 wherein the keyhole shaped cut-out is formed between adjacent teeth and the bend is located at about the centre of the rounded portion of the keyhole.

9. A harvester front as claimed in any one of claims 1 to 8 wherein the fingers are mounted to the drum by a hinged connection.

10. A harvester front as claimed in claim 9 wherein said hinged connection includes a stop against which the fingers bear under centrifugal force resulting from rotation of the drum.

11. A harvester front as claimed in claim 10 wherein said stops include a cushion of resilient material.

12. A harvester front as claimed in any one of claims 9 to 11 wherein said hinged connection includes a number of discrete sections along the length of the row of fingers.

13. A harvester front as claimed in any one of claims 1 to 12 wherein said flow of air is rapidly slowed in an expansion chamber defined by the cowl.

14. A harvester front as claimed in claim 13 wherein a soft curtain is provided in the path of said flow of air after it is slowed by the expansion chamber to direct impacting grain onto a transporting medium.

15. A harvester front as claimed in claim 14 further including directing means to change the direction of said flow of air after it is slowed by the expansion chamber and prior to impacting said curtain to improve separation of the entrained grain and MOG.

16. A harvester front as claimed in claim 15 wherein said directing means include a series of spaced vanes that project from the cowl into the flow of air.

17. A harvester front harvester as claimed in claim 16 wherein the vanes are angled at about 45° to the incident flow of air.

18. A harvester front as claimed in claim 17 wherein said vanes are arranged in opposed banks so that the flow is directed toward a central region.

19. A harvester front as claimed in any one of claims 13 to 18 wherein air is prevented from exiting the expansion chamber adjacent the fingers on the drum by a second set of correspondingly shaped air control fingers.

20. A harvester front as claimed in claim 19 wherein said air control fingers are stationary fingers extending across the width of the drum having apertures corresponding to the shape and size of the fingers mounted on the drum.

21. A harvester front as claimed in claim 19 or claim 20 further including a shroud extending beyond the air control fingers to define a rear opening in the stripper front adjacent the trailing side of the drum is arranged to direct the air flow generated by the movement of the fingers from the position of the air control fingers to the end of the cowl forward of the rear opening.

22. A harvester front as claimed in claim 21 wherein a series of air outlets are formed along the edge of the shroud to control the direction of the air flow.

23. A harvester front as claimed in claim 21 or claim 22 wherein the air flow from the rear opening is directed at least partially toward the ground to assist recovery of grain that has fallen to the ground.

24. A harvester front as claimed in any one of claims 1 to 23 further including a feeder/beater in the form of a cylindrical drum with frusto-conical end sections mounted for rotation about an axis normally transverse to the stripper front.

25. A harvester front wherein the feeder/beater drum is provided with transversely extending beaters extending outwardly from the surface.

26. A harvester front substantially as described with reference to the accompanying drawings.