IMPROVEMENTS IN COMBINE HARVESTERS

Abstract: A combine harvester, comprising a thresher unit (6), including a threshing cylinder (17) having its axis arranged transverse the longitudinal axis of the harvester and a thresher concave (8) in the form of a concave grille surrounding the lower part of the threshing cylinder (7) and defining therewith a passage for traversal by the crop harvested by the harvester in a direction parallel to the longitudinal axis of the machine. The combine harvester further includes a cleaning unit (18) including a pivoted bin (19) bearing at least two cleaning screens (20, 21) one above the other, conveyor means (10) which receive the grain separated by the thresher unit (6) and drop it on to the cleaning unit (18), means (23, 25) for directing a current of air at the product (P) which falls on to the cleaning unit (18) so as to separate the lighter chaff from the grain, a transverse accelerator roller (16) located beneath the discharge end (11) of the conveyor means (10) to accelerate the fall of the product, and a fixed wall (17) adjacent the accelerator roller (16) and defining therewith a passage through which the grain leaving the conveyor means (19) is accelerated, the fixed wall (17) being so formed as to incline the fall of the product (P) accelerated by the accelerator roller (16) relative to a vertical transverse plane.

Description: The present invention relates to combine harvesters of the conventional type consisting of a thresher unit, including a threshing cylinder having its axis arranged transverse the longitudinal axis of the harvester and a thresher concave in the form of a concave grille surrounding the lower part of the threshing cylinder and defining therewith a passage for traversal by the crop harvested by the harvester in a direction parallel to the longitudinal axis of the harvester, a cleaning unit including a pivoted bin carrying at least two cleaning screens located one above the other, conveyor means which receive the grain separated by the thresher unit and drop it on to the cleaning unit, and means for directing a current of air at the product dropping on to the cleaning unit, so as to separate the lighter chaff from the grain. The basic problem of the present invention is that of improving the pneumatic separation of the lighter chaff from the grain in order to reduce the work load on the cleaning sieves so that they can be made smaller. The main characteristic of the invention lies in the fact that the combine harvester further includes a transverse accelerator roller, located beneath the discharge end of the conveyor means, for accelerating the fall of the product, and a wall adjacent the accelerator roller, and defining therewith a passage through which the grain leaving the conveyor means is accelerated, the wall being so shaped as to incline the fall of product accelerated by the accelerator cylinder relative to a vertical transverse plane. Preferably the said wall surrounds the rear part (with reference to the direction of travel of the combine harvester) of the accelerator roller in such a manner as to divert the fall of product forwardly on to the cleaning unit. By virtue of the said characteristics, the pneumatic action of separating the lighter chaff from the grain is considerably improved, both because the product is accelerated by the accelerator cylinder, and also because the discharge of the product on to the cleaning unit is inclined to a vertical transverse plane, whereby the space traversed by the product under the action of the air current is greater than when the product falls vertically on to the cleaning screens. The Applicant, in Italian Patent Application 68256-A/83 (corresponding to the European Patent Application EP-A-No. 0 144 291) not yet published at the priority date of this Application, has already proposed a combine harvester provided with an accelerator roller located above the cleaning unit, and a wall cooperating with the accelerator roller for diverting the fall of product which falls on to the cleaning unit relative to a transverse vertical plane. The combine harvester proposed above, however, is of the so-called "axial flow" type, that is, it is provided with a thresher unit in which the product describes a helical trajectory around the threshing cylinder, moving from one end of the latter to the other. The product separated by the thresher unit is then conveyed and off-loaded on to a pair of transverse counter-rotating screw distributors (in this specification and in the following claims, the term "transverse" refers to a direction perpendicular to the longitudinal vertical plane of the combine harvester), located above the accelerator roller and arranged to distribute the product received from the thresher unit over the whole width of the harvester. In the present invention, the use, in combination with the accelerator roller, of a wall for diverting the fall of accelerated product has been applied to a combine harvester of the conventional type in which the product passes through the thresher unit in a longitudinal direction, in a plane perpendicular to the axis of the threshing cylinder. In this case the conveyor means which receive the separated grain from the thresher unit and drop it on to the accelerator roller may, for example, be constituted by a screw or a belt conveyor, and the use of the distributor screws illustrated in the prior (not pre-published) Patent Application is no longer necessary, in as much as the grain emerging from the conventional thresher unit is already distributed over the entire width of the machine. Further characteristics and advantages of the invention will emerge from the description which follows with reference to the appended drawing, provided purely by way of non-limiting example, which is a diagrammatic longitudinal-sectional view of a combine harvester according to the invention. The Figure illustrates a combine harvester 1 which has a fixed structure 2 mounted on front wheels 3 and rear wheels 4. The combine harvester is provided at its front end with a cutting platform 5 (only partially illustrated in the drawing) and a conventional thresher unit 6, including a threshing cylinder 7 with a transverse axis and a thresher concave 8 in the form of a concave grille, surrounding the lower part of the threshing cylinder 7. The passage defined between the threshing cylinder 7 and the concave 8 is designed to be traversed by the harvested crop in a direction parallel to the longitudinal axis of the combine harvester. The grain separated by the thresher unit 6 which falls beneath the thresher concave 8 is collected on a flat surface 9 extending towards the rear of the combine harvester. Above the surface 9 is a series of screw conveyors 10 (only one of which is visible in the drawing) arranged parallel to a longitudinal vertical plane through the combine harvester and arranged to convey the grain which falls beneath the thresher concave 8 to a discharge opening 11. The material which trasverses the passage between the concave 8 and the threshing cylinder 7 without falling beneath the concave 8 is discharged on to a shaking screen assembly 12 of conventional type, which pushes the straw towards an unloading end 13. The grain recovered by the shaking screen assembly falls on to the surface 9, where it is taken up by the screw conveyors 10 and carried to the discharge opening 11, or else on to a surface 14 arranged as an extension of the surface 9 beyond the unloading opening 11. Above the surface 14 there are further screw conveyors 15, driven by the same shafts as the screws 10, and so 30 arranged as to propel the grain which falls on to the surface 14 towards the discharge opening 11. Below the discharge opening 11 is an accelerator roller 16 for accelerating the fall of the product leaving the discharge opening 11. The structure of the accelerator roller 16 is not illustrated in the drawings in that it is known per se . Moreover, the elimination of these constructional details from the drawings renders the latter more immediately comprehensible. For example, the accelerator roller can be shaped in the manner described in the European Patent Application No. 0 073 179 by the same Applicant, which illustrates a combine harvester of the axial-flow type in which the product which falls on to the cleaning unit is projected in a vertical direction by an accelerator roller. Reference numeral 17 indicates a fixed transverse wall having a cross-section in the form of an arc of a circle, surrounding the rear part (in relation to the direction of travel of the combine harvester) of the cylinder of the accelerator roller 16, so as to divert the fall of product accelerated by the said roller 16 into a plane inclined forwardly of a vertical transverse plane. In the drawing, the reference P indicates the fall of accelerated product. The product emerging from the accelerator roller falls on to a cleaning unit 18 of the conventional kind comprising a pivoted bin 19 bearing a pair of superposed cleaning screens 20, 21. The pivoted bin 19 has a table 22 located forwardly of the upper screen 20, in the area towards which the fall P of product accelerated by the roller 16 is directed. Reference numeral 23 indicates a fan for directing a jet of air through pipes 24, 25 opening into the zone of the cleaning screens 20, 21 and into the zone to which the fall P of product accelerated by the roller 16 is directed, respectively. Below the cleaning screens 20, 21 are a collector 26, in which the grain is collected, and from which it is transferred to a tank 27 of the combine harvester, by a conveyor device of known type (not illustrated) and a collector 28 for the material to be subjected to further separation. The material collected in the collector 28 is passed back into the cycle by conveyor means of a tipe known per se (not illustrated), to be subjected to cleaning again. In operation, the product leaving the discharge opening 11 is accelerated by the roller 16 in passing through the passage defined between this roller and the wall 17. The latter deflects the fall of accelerated product into a forwardly-inclined fall, as illustrated in the drawing. The fall of deflected and accelerated product is invested by a current of air from the pipe 25, whereby the lighter chaff is separated from the heavier grain and deposited on the ground behind the combine harvester. The material which falls on to the table 22, which is part of the pivoted bin 19, is transferred to the cleaning screens 20, 21 where it is invested by the current of air from the pipe 24, which provides for further separation. The grain which reaches the collector 26 is conveyed to the tank 27 of the combine harvester, whilst the material which reaches the collector 28 is recycled to be cleaned again. By virtue of the fact that the accelerated fall of product is inclined to a vertical transverse plane, the space traversed by the product under the action of the current of air is increased, thereby enhancing the pneumatic separation. The cleaning unit 18 can therefore be made smaller, in that its work load is reduced. A device can be provided immediately below the accelerator roller for diverting the fall of product accelerated by the accelerator roller 16 towards the higher side of the combine harvester when the latter is inclined to one side; such a device may, for example, be of the type constituting the object of the previous Italian Patent Application 68257-A/83 by this Applicant as well as the corresponding European Patent Application No. 84830200.6 filed on the 29th June 1984 by the same Applicant. Naturally the present invention also extends to other models which achieve equal utility with the same innovative concept.

Claims: 1. A combine harvester, comprising - a thresher unit (6), including a threshing cylinder (17) having its axis arranged transverse the longitudinal axis of the harvester and a thresher concave (8) in the form of a concave grille surrounding the lower part of the threshing cylinder (7) and defining therewith a passage for traversal by the crop harvested by the harvester in a direction parallel to the longitudinal axis of the machine, - a cleaning unit (18) including a pivoted bin (19) bearing at least two cleaning screens (20, 21) one above the other, - conveyor means (10) which receive the grain separated by the thresher unit (6) and drop it on to the cleaning unit (18), - means (23, 25) for directing a current of air at the product (P) which falls on to the cleaning unit (18) so as to separate the lighter chaff from the grain, characterised in that the combine harvester further includes - a transverse accelerator roller (16) located beneath the discharge end (11) of the conveyor means (10) to accelerate the fall of the product, and - a fixed wall (17) adjacent the accelerator roller (16) and defining therewith a passage through which the grain leaving the conveyor means (19) is accelerated, the fixed wall (17) being so formed as to incline the fall of the product (P) accelerated by the accelerator roller (16) relative to a vertical transverse plane. 2. Combine harvester according to Claim 1, characterised in that the said fixed wall (17) surrounds the rear part (in relation to the direction of travel of the combine harvester) of the accelerator roller (16) so as to incline the fall of accelerated product P forwardly. 3. Combine harvester according to Claim 1, characterised in that the said conveyor means include a flat surface located beneath the thresher unit (6) and extending beyond the latter towards the rear of the combine harvester, and a series of screw conveyors (10) parallel to a longitudinal vertical plane through the combine harvester for transporting the grain which falls beneath the thresher concave (8) towards a discharge opening (11) located above the accelerator roller (16). 4. Combine harvester according to Claim 3, characterised in that it includes a shaking screen assembly (12) spaced above the said flat surface (9) and arranged to receive the straw leaving the thresher unit (6) and to carry it towards an unloading end (13) of the shaking screen assembly (12), and in that the combine harvester further includes an additional flat surface (14) located as an extension of the said flat surface (9) beyond the discharge opening (11), and a series of screw conveyors (15) situated above the additional flat surface (14) for carrying the grain which falls on to the additional flat surface (14) of the shaking screen assembly (12) to the aforesaid unloading opening (11).

Inventors: RAINERI, GIUSEPPE
Applicants: FIATGEOTECH - TECNOLOGIE PER LA TERRA S.P.A.
Application year: 1985
Main classification: A01F12
IPC codes: A01F12