Agricultural machinery

Abstract

The present invention relates to an agricultural machine (1), in particular a rotary mower, comprising: - at least one working element (2) for carrying out a work step, - at least one hydraulic drive (3) with at least one hydraulic pump (29) for driving the at least one working element (2), - at least one dynamically tensionable belt drive (5) for driving the hydraulic pump (29), wherein the belt drive (5) comprises: - at least one drive pulley (6) and at least one driven pulley (7) as well as at least one belt (8) connecting the drive pulley (6) with the driven pulley (7) and rotating around the two pulleys (6, 7), - wherein the belt (8) is tensioned around the two pulleys (6, 7), - wherein the drive pulley (6) is rotatably mounted about a drive axis of rotation (9) and the driven pulley (7) is rotatably mounted about a driven axis of rotation (10).In order to provide an agricultural work machine (1) in which belt wear of the belt (8) of the belt drive is reduced, it is provided according to the invention that the belt tension can be changed automatically depending on a load transmitted by the belt (8).

Description

The present invention relates to an agricultural working machine, in particular a combine harvester.The agricultural working machine has at least one working element for carrying out a working step. In order to be able to drive the working element, the agricultural working machine has at least one hydraulic drive with at least one hydraulic pump. In order to be able to drive the hydraulic pump in turn, at least one dynamically tensionable belt drive is assigned to the agricultural working machine. The belt drive has at least one rotatably mounted drive pulley, at least one rotatably mounted driven pulley and at least one belt, the latter connecting the drive pulley to the driven pulley and revolving the two pulleys, i.e. both the drive pulley and the driven pulley. During rotation of the drive pulley, the torque introduced is transmitted to the output pulley by means of the belt.In order to enable this continuously and also under difficult harvesting conditions, a tension of the belt necessary for the respective power transmission is required, which tension is also referred to as belt tension. The belt, which in turn has a load strand and an empty strand, is therefore tensioned with the belt tension around the two pulleys, wherein the belt tension must be adapted to the respective situation, in particular when a load to be transmitted is increased.Belt drives of this type are already known from the prior art in a large number. For example, DE 103 12 321 A1 describes a belt drive with a belt tensioner for providing a tension of the belt of the belt drive suitable for operation under difficult conditions. The required belt tension is generated by a compression spring, the prestress of which is in turn adjustable via an adjusting nut. The belt tension must be matched to the maximum power to be transmitted. However, at operating points where lower powers are required by the working member, such a high voltage is not necessary. However, a reduction in the belt tension can be effected only by adjusting the adjusting nut, i.e. manually.The disadvantages of known belt drives are therefore that the belt tensioners are matched for a maximum load to be transmitted, even if this load state occurs only in a few operating situations. This results in increased belt wear and decreased energy efficiency.The object of the present invention is therefore to provide an agricultural working machine in which the wear of the belt of the belt drive is reduced.The aforementioned object is achieved according to the invention by means of an agricultural working machine having the features of claim 1. Advantageous embodiments are the subject matter of the dependent claims.The agricultural working machine is characterized in that the belt tension can be automatically changed as a function of a load transmitted through the belt. In other words, the belt tension changes without manual intervention by an operator of the agricultural working machine.The working machine according to the invention has many advantages. In particular, the automatic adaptation of the belt tension ensures that the belt is always tensioned only to the respectively required extent. At operating points where lower powers are required by a working member of the agricultural working machine, the belt can be tensioned with a lower belt tension than at operating points where a corner power is called up by the working member. The adjustment of the belt tension is advantageously always effected in dependence on the load transmitted by the belt. The belt tension is thus always adapted to the conditions present at the respective operating points. In this way, the belt is not unnecessarily strained. A closing of the belt can therefore be significantly reduced, as a result of which its service life is increased.A preferred embodiment of the invention provides that the belt tension increases when the transmitted load is increased and decreases when the transmitted load is decreased. In this way, it is possible to prevent the belt from slipping as a result of a slip when the forces acting on runs of the belt are increased. It is likewise ensured that the belt tension can be adapted accordingly in the event of a loss or a reduction in the load to be transmitted.Preferably, the output disk can be mounted pivotably about an intermediate axis of rotation, wherein the intermediate axis of rotation is arranged between a first straight line formed by the load strand and a second straight line connecting the drive axis of rotation and the output axis of rotation, so that as a result of an increase in the torque transmitted by the belt, a distance between the drive axis of rotation and the output axis of rotation can be changed, so that the belt tension can be changed as a function of the torque.In other words, an increase in the torque introduced by the drive disk brings about a torque acting on the output disk, which torque results in the output disk pivoting about the intermediate axis of rotation. As a result, the distance between the input rotational axis and the output rotational axis is increased, thereby increasing the belt tension. The output disk is transferred from a starting position into a deflected position.This is made possible in that, as a result of the introduction of an increased useful force into the belt drive, a load strand force and a free strand force acting on the load strand and the free strand of the belt are increased or reduced. As a result of the arrangement of the intermediate axis of rotation between the two strands, the change in the forces brings about an introduction of a torque which results in a pivoting of the output disc about the intermediate axis of rotation. Also, due to the above arrangement, the pivoting of the driven pulley results in an increase in the distance between the two pulleys, thereby increasing the belt tension.It is likewise preferably provided that this state is partially or completely canceled when the useful force is reduced or eliminated, and the output disk is therefore transferred into the starting position, so that the distance between the output disk and the input disk is reduced and the belt tension is likewise reduced.According to a preferred embodiment of the invention, it is provided that the output disk is mounted pivotably on the intermediate axis of rotation by means of a retaining element. The holding element brings about the formation of a lever arm which, in conjunction with the forces acting on the output disk, introduces a torque into the output disk.Preferably, a retaining element can be provided which serves for fixing the output disk in a starting position when the belt drive is present in a load-free state. On the one hand, it can be provided that displacement of the driven disc out of its starting position is already prevented by an intrinsic weight of the driven disc. Added to this is preferably an own weight of a pump shaft of the hydraulic pump and further preferably an own weight of the holding element, provided this is provided. On the other hand, the initial position of the driven pulley can be fixed by the retaining member. A common feature of the aforementioned measures is that they are intended to prevent the driven pulley from moving relative to the drive pulley and thus changing the belt tension or even causing the belt to spring off the pulleys.A further preferred embodiment of the invention provides that the retaining element is designed in the form of a tension spring. A tension spring has proven to be particularly advantageous for the formation of a retaining element. The tension spring counteracts a rotation of the output disk due to its prestress. Preferably, the tension spring is connected to the holding element in a manner transmitting force on one side in order to fix the holding element in its position.According to a preferred embodiment of the invention, it is further provided that a pump shaft of the hydraulic pump is arranged on the output disk, so that the torque provided by the belt drive can be transmitted to the pump shaft and the hydraulic pump can thus be driven. As a result of such an arrangement, a separate transmission of the torque from the output disk to the pump shaft is not necessary. Rather, this is transmitted directly to the pump shaft.Preferably, it can be provided that the working element to be driven by the hydraulic pump is a position-variable working element of the agricultural working machine. A "position-variable working element" is understood to mean a working element which can be transferred between at least two positions during operation of the agricultural working machine.According to a preferred embodiment of the invention, it is provided that the working member to be driven is a chaff distributor of the agricultural working machine, wherein the chaff distributor is preferably pivotable for setting an ejection direction. The required driving power of the chaff distributor can vary depending on a throughput and the desired ejection width of the chaff to be ejected on the field. Consequently, the required drive power of the chaff distributor can change as a function of different harvesting situations, so that the belt tension automatically adapting to the load situation is particularly advantageous here.The invention is explained in more detail below with reference to an exemplary embodiment which is illustrated in the figures. It shows: FIG. 1 : a vertical section through an agricultural working machine according to the invention. FIG. 2 : a detailed view of a belt drive of the agricultural working machine from FIG. 1. FIG. 3 : shows a further detail view of the belt drive from FIG. 2. FIG. 4 : a detailed view in the area of a chaff distributor of the agricultural working machine from FIG. 1. FIG. 5 : a detailed view in the region of an output disk of the belt drive from FIG. 2.An agricultural working machine 1 according to the invention, as shown in FIG. 1, comprises a plurality of working members 2 for performing an agricultural working operation to be carried out by the agricultural working machine 1. The agricultural working machine 1 shown in FIG. 1 is designed as a combine harvester for abbating a field 20. In this case, the individual working members 2 each carry out a working step of the harvesting process. The agricultural working machine 1 shown in FIG. 1 has, among other things, a working element 2 designed as a chaff distributor 19 which is provided to distribute the chaff obtained during the harvesting process to a field 20. The chaff spreader 19 shown in detail in FIG. 4 can be pivoted about a horizontal axis to set an ejection angle. Furthermore, the chaff spreader requires a varying drive power depending on an ejection width of the chaff to be ejected on the field 20 as well as an amount of the chaff to be ejected.In order to be able to adapt the position of the chaff distributor 19 and to enable a continuously variable speed adjustment, the agricultural working machine 1 has a hydraulic drive 3 assigned to the chaff distributor 19, which in turn is provided with a hydraulic pump 29. In order to be able to drive the hydraulic pump 29 of the hydraulic drive 3, a belt drive 5 is provided. This is designed to be dynamically stretchable. The agricultural working machine 1 thus has mechanical and hydraulic elements for driving the chaff distributor 19.The belt drive 5, which can be seen particularly well in FIGS. 2, 3, 4 to 5, has a drive pulley 6, a driven pulley 7 and a belt 8. The belt 8 connects the two pulleys 6, 7 in that the belt 8 rotates the pulleys 6, 7, wherein the belt 8 is tensioned with a belt tension about the two pulleys 6, 7, so that a torque introduced by the drive pulley 6 can be transmitted to the output pulley 7 by means of the belt 8. Both the drive disk 6 and the driven disk 7 are rotatably mounted about their own axis of rotation, a drive axis of rotation 9 and a driven axis of rotation 10.The hydraulic pump 29 is disposed on a frame 28 of the agricultural working machine 1 via a holding element 15. The holding element 15 is mounted pivotably about an intermediate axis of rotation 11. Due to the connection of the hydraulic pump 29 via the holding element 15, the hydraulic pump 29 is mounted with its pump shaft 18 pivotably about the intermediate axis of rotation 11. The same applies to the driven plate 7 due to the arrangement of the driven plate 7 on the pump shaft 18 of the hydraulic pump 29; the drive plate 6, on the other hand, is fixed in a fixed position on the frame 28.For driving the working members 2, for example also the chaff distributor 19, a torque is first introduced into the belt drive 5 via the drive pulley 6. During operation of the belt drive 5, the drive pulley 6 transfers the latter by means of the belt 8 to the driven pulley 7; the driven pulley 7 is arranged-as can be seen in FIG. 2-on a pump shaft 18 of the hydraulic pump 29, so that the torque can be directly transferred to the pump shaft 18 of the hydraulic pump 29 and the latter can be driven in this way. The transmission ratio between the input disk 6 and the output disk 7 determines the torque acting on the output disk 7. In the belt drive 5 shown in the figures, a diameter of the drive pulley 21 exceeds a diameter of the output pulley 22, so that the load strand 12 and the empty strand 23 of the belt 8 are set obliquely.The force to be transmitted from the input disk 6 to the output disk 7 is referred to as the useful force F U. As a result, different forces are produced on the two belt sections of the belt 8, namely on the load strand 12 and on the empty strand 23, which forces are referred to below as load strand force F L and empty strand force F LS. The forces are drawn in FIGS. 2 and 5.In order to prevent the belt 8 from slipping due to a slip when the strand forces F L, F LS increase, the belt 8 requires a certain belt tension. In the load-free state, initially only the prestressing force F V acts in the belt 8. When the useful force F U is increased, the load strand force F L, increases, while the empty strand force F LS decreases. Due to the torque equilibrium, the difference between load strand force F L and empty strand force F LS corresponds to the load force F U. to be transmitted. The aforementioned relationships can be represented as follows:The load-independent prestressing force F V is determined by the weight acting on the hydraulic pump 29, the output disk 7 and the holding element 15. Added to this is a clamping force generated by a retaining element 16 designed in the form of a clamping spring 17, which holds the retaining element 15 together with the output disk 7 and the hydraulic pump in position. The pretensioning force F V ensures that the aforementioned components do not pivot about the intermediate axis of rotation 11 even when there is little or no load present and in this way would cause the belt 8 to be relaxed and possibly to spring off from the pulleys 6, 7. Situations of low or no load are, for example, road drives in which the chaff spreader 19 is not required. The same applies to the switched-off state of the chaff distributor 19. In the aforementioned situations, the driven disk 7 is in the starting position, in which a distance 4 between the driven rotational axis 10 and the drive rotational axis 9 is minimal.As a result of an introduction of a torque through the drive disk 6, the useful force F U, as a result of which the load strand force F L increases, takes place, while the empty strand force F LS decreases to the same extent. This occurs temporarily when a corner power is called up by the hydraulic drive 3, but then also requires a higher tension of the belt 8.According to the invention, the change in the belt tension takes place in a load-dependent manner. In order to be able to dynamically adapt the belt tension to the power transmitted by the belt 8, the driven pulley 7 is mounted pivotably about the intermediate axis of rotation 11.The intermediate axis of rotation 11 is arranged between the two disks 6, 7. At the same time, the intermediate axis of rotation 11 is arranged between a first straight line 13 and a second straight line 14. The first straight line 13 is formed by the load strand 12 in a tensioned state, while the second straight line 14 is determined by an imaginary connection of the drive axis of rotation 9 and the driven axis of rotation 10, which is provided with the reference sign 24 in FIG. 3.As a result of an increase in the required load, an increasing useful force F U, transmitted by the belt 8 causes the hydraulic pump 29 to be pivoted together with the output disk 7 about the intermediate axis of rotation 11, so that the distance 4 between the output axis of rotation 9 and the drive axis of rotation 10 increases and the belt 8 is tensioned. Here, the change of the useful force F U causes a change of the load strand force F L and the empty strand force F LS. Due to the above-described arrangement of the intermediate axis of rotation 11, a torque is caused which results in the output disk 7 together with the pump shaft 18 being pivoted about the intermediate axis of rotation 11.The lines of action 25, 26 of the load-bearing force F L and of the free-strand force F LS and the associated distances L LE, L LA to the intermediate axis of rotation 11 (lever arms) are drawn in FIG. 5. The ratio of the two forces F L, F LS to the lever arms L LE, L LA can be expressed as follows:In the figures, the direction of rotation 27 of the drive disk 6 is oriented counterclockwise, so that the distance 4 between the drive axis of rotation 9 and the driven axis of rotation 10 increases. In this way, the belt tension is increased.Advantageously, the belt tension is thus adapted dynamically and load-dependently. In this way, the belt tension can be set to "normal operation" first, i.e. when the belt drive 5 is not currently running on the corner power of the hydraulic drive. Only when the corner performance is reached is an automatic adaptation of the belt tension carried out. Tensioning rollers or other measures for adapting the belt tension are therefore not required.Likewise, a omission or a reduction of the useful force causes a transfer of the drive pulley 6 into the initial state shown in FIGS. 2, 3 to 4, so that the distance 4 between the two pulleys 6, 7 is reduced, whereby the belt tension is likewise reduced. This process also takes place advantageously automatically, i.e. without manual intervention.List of reference characters1 Agricultural working machine 2 Working element 3 Hydraulic drive 4 Distance 5 Belt drive 6 Drive disc 7 Driven disc 8 Belt 9 Drive axis of rotation 10 Driven axis of rotation 11 Intermediate axis of rotation 12 Load strand 13 First straight line 14 Second straight line 15 Holding element 16 Retaining element 17 Tension spring 18 Pump shaft 19 Chaff distributor 20 Field 21 Diameter of the drive disc 22 Diameter of the driven disc 23 Empty strand 24 Connection 25 Line of action of the load strand force 26 Line of action of the empty strand force 27 Direction of rotation 28 Frame 29 Hydraulic pump L LA Lever arm L LE Lever arm F LS Empty strand force F L Load strand force F V Prestressing force F U Useful forceReferences included in the specificationThis list of documents cited by the applicant has been produced in an automated manner and is only included for the better information of the reader. The list is not part of the German patent application or utility model application. The DPMA does not take any adhesion for any faults or omissions.Patent Literature citedDE 103 12 321 A1

[0004]

Claims

Agricultural working machine (1), in particular rotary mowers, comprising - at least one working element (2) for carrying out a working step, - at least one hydraulic drive (3) having at least one hydraulic pump (29) for driving the at least one working element (2), - at least one dynamically tensionable belt drive (5) for driving the hydraulic pump (29), wherein the belt drive (5) comprises ▪ at least one drive disc (6) and at least one driven disc (7) and at least one belt (8) connecting the drive disc (6) to the driven disc (7) and circulating the two discs (6, 7), ▪ wherein the belt (8) is tensioned with a belt tension about the two discs (6, 7), ▪ wherein the drive disc (6) is mounted rotatably about a drive axis of rotation (9) and the driven disc (7) is mounted rotatably about a driven axis of rotation (10), characterized in that, the belt tension is automatically variable in response to a load transmitted through the belt (8).Agricultural working machine (1) according to Claim 1, characterized in that the belt tension increases when the load transmitted increases and decreases when the load transmitted decreases.Agricultural working machine (1) according to Claim 1 or 2, characterized in that the output disc (7) is additionally mounted pivotably about an intermediate axis of rotation (11), wherein the intermediate axis of rotation (11) is arranged between a first straight line (13) formed by a load strand (12) and a second straight line (14) connecting the drive axis of rotation (9) and the output axis of rotation (10), such that as a result of an increase in the load transmitted by the belt (8), a distance (4) between the drive axis of rotation (9) and the output axis of rotation (10) can be changed, such that the belt tension can be changed as a function of the torque.Agricultural working machine (1) according to one of the preceding claims, characterized in that the driven disc (7) is mounted pivotably on the intermediate axis of rotation (11) by means of a retaining element (15).Agricultural working machine (1) according to Claim 3 or 4, characterized bya retaining element (16) for fixing the driven pulley (7) in a starting position when the belt drive (5) is in a load-free state.Agricultural working machine (1) according to Claim 5, characterized in that the retaining element (16) is designed in the form of a tension spring (17).Agricultural working machine (1) according to one of Claims 3 to 6, characterized in that a pump shaft (18) of the hydraulic pump (29) is arranged on the output disc (7), with the result that the torque provided by the belt drive (5) can be transmitted to the pump shaft (18) and the hydraulic pump (29) can thus be driven.Agricultural working machine (1) according to one of the preceding claims, characterized in that the working element (2) to be driven by the hydraulic pump (29) is a position-variable working element (2) of the agricultural working machine.Agricultural working machine (1) according to Claim 8, characterized in that the position-variable working element (2) is a chaff distributor (19) of the agricultural working machine (1).

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