KNIFE DRIVE DEVICE

Description

[0001] The invention relates to an attachment for a harvesting machine with an oscillating blade and a hydraulic blade drive device according to the preamble of claim 1. Harvesting machines, in particular self-propelled agricultural harvesting machines, such as forage harvesters or combine harvesters, are generally equipped with an attachment designed as a cutting unit during harvesting. Such attachments have a plurality of oscillating blades on the front, which are arranged on one or more blade bars. Hydraulic blade drive devices for driving the oscillating blades, which in particular drive the blade bar on which the blades are arranged, are known from the prior art.

[0002] DE 196 14 092 shows an attachment with such a blade drive system. The blade bar with the blades is set into an oscillating motion by means of a double-acting slave cylinder. A hydraulic pump supplies hydraulic fluid to the slave cylinder. The hydraulic pump is designed as a piston pump with two pistons, with one piston acting on each side of the double-acting slave cylinder via pressure lines.

[0003] DE 11 61 448 B also shows an attachment for a harvesting machine according to the preamble of claim 1.

[0004] In such blade drive systems, a gear difference often arises between the pistons of the hydraulic pump and the slave cylinder due to the dynamics, particularly the inertia, of the oil and its compressibility. In the worst case, the gear difference accumulates with each stroke of the cylinder units, causing the cylinder units to operate in opposite directions. As a result, the piston of the slave cylinder no longer reaches the outer stops as intended, and consequently, the blade bar does not execute the intended oscillating movement. This behavior is particularly critical with multiple oscillating blade bars that are driven in opposite directions to dampen vibrations of the attachment. Therefore, optimal synchronization of the blade bars is not guaranteed by the hydraulic blade drive system disclosed in DE 196 14 092.

[0005] It is therefore an object of the invention to avoid the described disadvantages of the prior art and in particular to provide a hydraulic knife drive device which ensures a positively guided hydraulic drive and an independent synchronization of the knives.

[0006] This object is achieved according to the invention by the characterizing features of claim 1.

[0007] According to claim 1, an attachment for a harvesting machine with an oscillating blade and a hydraulic blade drive device for the oscillating blade is proposed, comprising at least one slave cylinder for driving the oscillating blade, wherein the at least one slave cylinder is driven by at least one first master cylinder, wherein the at least one first master cylinder has a larger displacement volume than the at least one slave cylinder.

[0008] Because the first master cylinder has a larger displacement than the slave cylinder, the first master cylinder continues to pump oil to the slave cylinder even after the slave cylinder has reached its intended outer end position. This design of the cylinders ensures that the reciprocating piston of the slave cylinder reaches the intended outer end position and remains there until the reciprocating piston of the first master cylinder, and thus also the blades, have also reached their outer end position. This results in a positively guided synchronization of the slave cylinder with the first master cylinder in an end position. A path difference due to compressibility and dynamics within the hydraulic blade drive system is avoided. The end position corresponds to the turning point of the direction of movement of a reciprocating piston within the cylinder.

[0009] In an advantageous embodiment, the at least one slave cylinder can be designed as a double-acting cylinder, so that one slave cylinder is sufficient to drive the blades and no further slave cylinder is required to drive the blades on the front side of the cutting unit.

[0010] In an advantageous development, the at least one slave cylinder can be connected to a reservoir via a pressure relief valve on the piston side and the rod side, respectively. When the reciprocating piston located within the slave cylinder reaches its outer limit position, the additionally pumped oil can escape through the pressure relief valves and be fed to the reservoir.

[0011] In addition to pressure limitation, this advantageous development offers the possibility of replacing the oil contained in the hydraulic knife drive system with cooler oil from the reservoir. The reservoir can, for example, be a larger container or tank containing a certain amount of oil.

[0012] According to the invention, the at least one slave cylinder is drivingly connected to a pivotably mounted lever, wherein the lever is arranged at the end of the knife.

[0013] Such a lever can be designed, for example, as a hollow shaft or profile element and offers the advantage that the slave cylinder can be positioned at a distance from the blade, especially since the available space in the blade area is very limited. Furthermore, a lever can be mounted in such a way that it increases the amplitude of the oscillation movement transmitted from the slave cylinder to the blades.

[0014] It is particularly advantageous if the at least one first master cylinder is connected to the reservoir via at least one check valve. The master cylinder can thus draw in a quantity of oil previously discharged via the check valves via the reservoir. Furthermore, the design offers the advantage that the hydraulic blade drive device is configured for automatic venting. Due to the larger displacement of the first master cylinder compared to the slave cylinder, air within the blade drive device is discharged via the pressure relief valves and replaced with oil via the check valves.

[0015] A particularly simple implementation of the hydraulic knife drive device according to the invention provides that the at least one first master cylinder is designed as a double-acting first master cylinder.

[0016] It is advantageous if the at least one first master cylinder is driven by a crank drive. A crank drive is known, for example, from the design of an internal combustion engine. A crank drive offers the particular advantage that the speed curve of the reciprocating piston within the master cylinder has a sinusoidal curve, with the speed reaching a minimum towards the end positions of the reciprocating piston. The sinusoidal speed curve of the reciprocating piston assigned to the first master cylinder is essentially transferred to the reciprocating piston assigned to the slave cylinder and thus to the blades. This enables a material-friendly drive of the blades, especially since abrupt braking and acceleration is avoided. Furthermore, the vibrations transferred to the structure of the attachment can be dampened.

[0017] In an advantageous further development, the double-acting first master cylinder can be connected to the reservoir on the piston side and rod side via a check valve each, so that the master cylinder can suck oil from the reservoir on the piston side and rod side.

[0018] To ensure the interaction of the first master cylinder with the slave cylinder, the at least one first master cylinder and the at least one slave cylinder can be hydraulically connected to one another both on the piston side and on the rod side, wherein in particular a first hydraulic line connects the piston sides and a second hydraulic line connects the rod sides of the cylinders.

[0019] In particular, the hydraulic knife drive device can comprise a double-acting first master cylinder and a double-acting slave cylinder, wherein the first master cylinder and the slave cylinder are hydraulically connected to one another, wherein the slave cylinder is connected to the reservoir on the piston side and rod side via a pressure relief valve, wherein the first master cylinder is connected to the reservoir on the piston side and rod side via a check valve, wherein the first master cylinder is driven by means of a crank drive.

[0020] In a preferred embodiment, the hydraulic knife drive device can have at least one second master cylinder, wherein the at least one first and at least one second master cylinder are preferably designed as single-acting cylinders, wherein the at least one first and at least one second master cylinder are hydraulically connected to the at least one slave cylinder, wherein the at least one first and at least one second master cylinder are each connected to the reservoir via a check valve. In this case, it can be provided that the first master cylinder supplies the slave cylinder with oil on the piston side and the second master cylinder supplies the slave cylinder with oil on the rod side. Alternatively, the slave cylinder can also be supplied with oil from the master cylinders in the opposite way.What is particularly advantageous about the embodiment is that the stroke volumes of the first and second master cylinders can be designed differently from one another, so that a more complex and more expedient synchronization of the first and second master cylinders with the slave cylinder is possible.

[0021] In an advantageous development, the at least one second master cylinder can have a smaller displacement than the at least one first master cylinder, wherein the displacement of the at least one second master cylinder preferably substantially corresponds to the displacement of the at least one slave cylinder. Because the displacement of the second master cylinder is smaller than that of the first master cylinder, the dwell time of the reciprocating piston assigned to the slave cylinder in its second end position of travel is reduced, the oil is compressed less and thus heated less. However, synchronization still occurs in a first end position of travel of the slave cylinder by means of the first master cylinder.

[0022] In an advantageous further development, the master cylinders can be driven by a crank mechanism. This allows a sinusoidal speed profile of the pistons assigned to the master cylinders to be achieved. Furthermore, it is particularly advantageous if the master cylinders are driven jointly by a crank mechanism to achieve simple synchronization of the master cylinders.

[0023] In particular, the hydraulic knife drive device can comprise two single-acting first master cylinders and two single-acting second master cylinders, wherein a first master cylinder and a second master cylinder are each hydraulically connected to a double-acting slave cylinder, wherein the slave cylinders are connected to a reservoir on the piston side and rod side via a pressure relief valve, wherein the first and second master cylinders are each connected to the reservoir via a check valve, wherein the first and second master cylinders are jointly driven via a crank drive, wherein the drive of the first master cylinder is 180 degrees out of phase with the drive of the second master cylinder.

[0024] Preferably, the attachment has two cutter bars, and the cutter drive device has at least two slave cylinders, wherein the cutter drive device is configured such that the slave cylinders drive the cutter bars in opposite directions. In particular, a configuration of the cutter drive device with two slave cylinders allows two cutter bars with knives located thereon to be driven in opposite directions, thus providing vibration compensation and reducing or even eliminating the vibrations transmitted from the cutter bars to the attachment structure.

[0025] The invention has many advantages. Due to the flexible hydraulic lines of a hydraulic knife drive system, it can be easily integrated into the front attachment compared to a conventional mechanical knife drive system. This is particularly advantageous for front attachments with length-adjustable cutting tables. The easy integration and small space requirement of hydraulic knife drive systems also simplifies the arrangement of the slave cylinders in a central area of the front attachment or knife bar. A central drive also has the advantage that the side walls of the front attachment can be made narrower by eliminating the lateral drive of the knives or knife bars, and contact of the crop with housings arranged on the front attachment and the resulting losses are avoided.Furthermore, with a central drive, fewer forces act on the outside of the housing of the attachment, so that the entire housing can be made lighter.

[0026] Further advantageous embodiments are the subject of further subclaims and are described below with reference to an embodiment illustrated in several figures. They show: Figure 1 shows a schematic plan view of an attachment, Figure 2 shows a schematic representation of the hydraulic knife drive device, Figure 3 shows a further embodiment of the hydraulic knife drive device, Figure 4 shows a section of a cutting unit with a lever for transmitting an oscillating movement to the knives.

[0027] In the Figur 1 1 represents an attachment designed as a cutting unit 1, which has a cutting table 2. The cutting table 2 accommodates a mowing blade consisting of a blade bar 3 and a plurality of blades 4 mounted thereon, which have cutting edges pointing in both directions of movement. The blades 4 are guided in a plurality of fingers 5, which are attached to the cutting table 2 and point with their tips in the mowing direction.

[0028] As a rule, cutting units 1 have a reel (not shown in detail here) which is generally known and runs transversely to the direction of travel and acts on the still uncut crop. The reel primarily has the task of feeding the crop to the cutter bar 3. The knives 4 or the cutter bar 3 are set in an oscillating movement by a hydraulic knife drive device 6 (to be explained in more detail later), so that the crop is cut and falls onto the cutting table 2. The crop is then fed, possibly with further action from the reel, to the inclined conveyor 7 by means of a generally known intake auger (not shown here). The inclined conveyor 7 then feeds the crop to a processing device (not shown), such as a threshing and separating device of a combine harvester. The cutting table 2 of the Fig. 1 The cutting unit 1 shown is designed to be adjustable in length in the mowing direction.

[0029] The entire cutting unit 1 is preferably connectable to the inclined conveyor 7 by a coupling device, wherein the drive of the cutting unit 1 is effected from a shaft (not shown) arranged in the inclined conveyor 7 via a first cardan shaft 8 to an angle drive 9 located laterally on the cutting unit 1 and known per se. Fig. 1 The cutting unit 1 shown has a drive shaft 10 between the cardan shaft 8 and the angle drive 9, which transmits the drive torque from the cardan shaft 8 to the angle drive 9. To adjust the speed, a gearbox can be provided, for example, between the drive shaft 10 and the cardan shaft 8. The cardan shaft 8 and drive shaft 10 are arranged in the rear area of the cutting unit 1. The angle drive 9 drives the intake auger and the reel.

[0030] The hydraulic knife drive device 6 is provided for setting the knives 4 in an oscillating movement. In the illustrated embodiment, this comprises two slave cylinders 11. The slave cylinders 11 are arranged in the center of the cutting unit 1 and are drivingly connected to the knives 4 in a manner to be explained in more detail below. The cutting unit 1 comprises two laterally offset knife bars 3, each of which carries a plurality of knives 4. The two slave cylinders 11 each set one of the knife bars 3 in an oscillating movement, wherein the oscillating movement of the knife bars 3 is 180 degrees out of phase with each other. In an alternative embodiment, just one knife bar 3 and one slave cylinder 11 drivingly connected to it can be provided.Analogously, three, four or more cutter bars 3 can also be provided, each of which is drivingly connected to a slave cylinder 11.

[0031] Fig. 2 shows an embodiment of the hydraulic knife drive device 6 in a schematic representation. In the exemplary embodiment shown, the piston rod 12 of the slave cylinder 11 is directly connected to the knife bar 3. However, an indirect arrangement of the slave cylinder 11 with the knife bar 3, by means of a lever 13 to be explained in more detail below, is within the scope of the invention. Furthermore, the slave cylinder 11 can have an end-position damping (not shown), in particular a hydraulic end-position damping or end-position damping formed with one or more spring elements, which is designed and provided to dampen the stroke movement of the lifting piston 24 in the region of the end positions.

[0032] The slave cylinder 11 is driven by a first master cylinder 14. For this purpose, the master cylinder 14 and slave cylinder 11 are designed as double-acting cylinders 11, 14 and are hydraulically connected to each other. A first hydraulic line 15 connects the first master cylinder 14 and the slave cylinder 11 on the piston side, and a second hydraulic line 16 connects the rod side. Alternatively, a connection of the respective piston side to the respective rod side of the cylinders 11, 14 is also possible.

[0033] The first master cylinder 14 has a larger displacement than the slave cylinder 11. This ensures that, despite the dynamics and compressibility of the oil, the slave cylinder 11 is moved to the intended outer travel limit and remains there briefly until the first master cylinder 14 has also moved to the outer travel limit. This leads to a positively guided synchronization of the slave cylinder 11 with the first master cylinder 14.

[0034] The slave cylinder 11 is connected to a pressure relief valve 17 on both the piston side and the rod side. Fig. 2 For this purpose, pressure relief valves 17 are assigned to the first and second hydraulic lines 15, 16, which connect the hydraulic lines 15, 16 to a reservoir 18. When the outer travel limit of the slave cylinder 11 is reached, the additional oil pumped due to the larger displacement of the master cylinder 14 can escape and be fed to the reservoir 18.

[0035] The first master cylinder 14 is connected to a check valve 19 on both the piston and rod sides. For this purpose, a check valve 19 is assigned to each of the first and second hydraulic lines 15, 16, which connect the hydraulic lines 15, 16 to the reservoir 18. Oil is supplied to the first master cylinder 14 through the check valves 19, which oil has previously been discharged via the check valves 17. A cooling system (not shown here) can be provided within the reservoir 18 to lower the oil temperature. Furthermore, the reservoir 18 can be pressurized to support the intake phase of the master cylinder 14.

[0036] The first master cylinder 14 is driven by a crank mechanism 20, which sets the piston 21 of the first master cylinder 14 in an oscillating motion with a sinusoidal speed profile, wherein the speed of the piston 21 assumes a minimum towards the outer turning points or end positions of the piston 21. Fig. 2 The schematically illustrated crank drive 20 comprises a crankshaft 22 which is set in a rotational movement and is drivingly connected to the reciprocating piston 21 via a push rod 23. The oscillating movement of the reciprocating piston 21 of the first master cylinder 14 is essentially transferred to the reciprocating piston 24 of the slave cylinder 11. Compared to a valve-controlled hydraulic drive of the knives 4 with a substantially rectangular speed profile, the sinusoidal speed profile is gentler on the material, and the oscillating movement of the knives 4 is transferred to a lesser extent to the structure of the cutting unit 1. The crank drive 20 can, for example, be arranged at the rear of the cutting unit 1 and be drivingly connected by means of the drive shaft 10 or cardan shaft 8.

[0037] Fig. 3 shows a further embodiment of a hydraulic knife drive device 6 according to the invention. Fig. 3 The illustrated knife drive device 6 comprises two double-acting slave cylinders 11, two single-acting first master cylinders 14, and two single-acting second master cylinders 25. A first master cylinder 14 and a second master cylinder 25 are each hydraulically connected to a slave cylinder 11. A first hydraulic line 15 connects the piston side of a first master cylinder 14 to the piston side of a slave cylinder 11, and a second hydraulic line 16 connects the piston side of the second master cylinder 25 to the rod side of a slave cylinder 11.

[0038] Analogous to the Fig. 2 In the embodiment described, check valves 19 are assigned to the master cylinders 14, 25, which connect the master cylinders 14, 25 to the reservoir 18. Furthermore, a pressure relief valve 17 is assigned to each of the slave cylinders 11 on the piston side and on the rod side, by means of which the slave cylinders 11 are connected to the reservoir 18. For this purpose, the first and second hydraulic lines 15, 16 are each connected to the reservoir 18 by a pressure relief valve 17 in a region facing the slave cylinder 11 and are each connected to the reservoir 18 by means of a check valve 19 in a region facing the master cylinder 14, 25.

[0039] As previously described, the displacement of the first two master cylinders 14 is greater than the displacement of the slave cylinders 11 for synchronization with the slave cylinders 11. This ensures that the reciprocating piston 24 assigned to the respective slave cylinder 11 reaches a first intended end position of travel and synchronizes with the respective reciprocating piston 21 of the first master cylinder 14. The displacement of the second master cylinders 25 is smaller than the displacement of the first master cylinder 14 and, in the illustrated embodiment, corresponds to the displacement of the slave cylinder 11.

[0040] Because the displacement of the respective second master cylinder 25 is smaller than that of the first master cylinder 14, the dwell time of the piston 24 assigned to the slave cylinder 11 in its second end position is reduced, the oil is compressed less and thus heated less. It should be noted that the displacement of the respective second master cylinder 25 can also be larger or smaller than the displacement of the slave cylinder 11.

[0041] The first and second master cylinders 14, 25 are driven jointly by means of a crank drive 20, wherein the movement of the reciprocating pistons 21 of the first master cylinder 14 is 180 degrees out of phase with the reciprocating pistons 26 of the second master cylinder 25.

[0042] The two slave cylinders 11 drive two cutter bars 3 (not shown here) in opposite directions. The slave cylinders can be arranged directly on the cutter bars 3 or as Fig. 4 shows, according to the invention, the knife bars 3 are driven by means of a lever 13.

[0043] For this purpose, the Fig. 4The lever 13 shown is mounted at one outer end for rotation about a vertically extending axis 27. At its other end, the lever 13 is fixedly connected, for example, by screwing, to the cutter bar 3. The cutter bar 3 holds the blades 4. The slave cylinder 11 is articulated to the lever 13 between the two outer ends of the lever 13. The piston rod 12 of the lifting piston 24 associated with the slave cylinder 11 can, for example, be arranged with its outer end for rotation on the lever 13. The driving of the cutter bar 3 or the knives 4 by means of a lever 13 enables a spaced arrangement of the slave cylinder 11 from the cutter bar 3 in a rear region of the cutting unit 1. Furthermore, the lever 13 increases the amplitude of the stroke movement of the lifting piston 24 assigned to the slave cylinder 11, which is transmitted to the cutter bar 3. List of reference symbols:

[0044] 1 Cutting unit 2 Cutting table 3 Knife bar 4 Knife 5 Finger 6 Knife drive device 7 Feeder 8 Cardan shaft 9 Angular drive 10 Drive shaft 11 Slave cylinder 12 Piston rod 13 Lever 14 First master cylinder 15 First hydraulic line 16 Second hydraulic line 17 Pressure relief valve 18 Reservoir 19 Check valve 20 Crank drive 21 Reciprocating piston 22 Crankshaft 23 Push rod 24 Reciprocating piston 25 Second master cylinder 26 Reciprocating piston 27 Axle

Claims

1. A front attachment for a harvesting machine, with an oscillating cutter (4) and a hydraulic cutter driving device (6) for the oscillating cutter (4), comprising at least one slave cylinder (11) for driving the oscillating cutter (4), wherein the at least one slave cylinder (11) is driven by at least one first master cylinder (14), wherein the at least one first master cylinder (14) has a larger piston displacement than the at least one slave cylinder (11), characterized in that the at least one slave cylinder (11) is operatively connected to a pivotably mounted crank (13), wherein the end of the crank (13) is disposed on the cutter (4).

2. The front attachment according to claim 1, characterized in that the at least one slave cylinder (11) is constructed as a double acting cylinder.

3. The front attachment according to claim 1 or claim 2, characterized in that, on the piston side and rod side, the at least one slave cylinder (11) is connected to a reservoir (18) via a respective pressure relief valve (17).

4. The front attachment according to one of claims 1 to 3, characterized in that the at least one first master cylinder (14) is connected to the reservoir (18) via at least one check valve (19).

5. The front attachment according to one of claims 1 to 4, characterized in that the at least one first master cylinder (14) is constructed as a double acting cylinder.

6. The front attachment according to claim 5, characterized in that the at least one first master cylinder (14) is driven by a crank drive (20).

7. The front attachment according to one of claims 5 to 6, characterized in that on the piston side and rod side, the at least one first master cylinder (14) is connected to the reservoir (18) via a respective check valve (19).

8. The front attachment according to one of claims 5 to 7, characterized in that the at least one first master cylinder (14) and the at least one slave cylinder (11) are connected together hydraulically on both the piston side as well as on the rod side, wherein in particular, a first hydraulic line (15) connects the piston sides together and a second hydraulic line (16) connects the rod sides of the cylinders together.

9. The front attachment according to one of claims 5 to 8, characterized in that the hydraulic cutter driving device (6) comprises a double acting first master cylinder (14) and a double acting slave cylinder (11), wherein the first master cylinder (14) and the slave cylinder (11) are connected together hydraulically, wherein on the piston side and rod side, the slave cylinder (11) is connected to the reservoir (18) via a respective pressure relief valve (17), wherein on the piston side and rod side, the first master cylinder (14) is connected to the reservoir (18) via a respective check valve (19), wherein the first master cylinder (14) is driven by means of a crank drive (20).

10. The front attachment according to one of claims 1 to 4, characterized in that the hydraulic cutter driving device (6) has at least one second master cylinder (25), wherein preferably, the at least one first and the at least one second master cylinders (14, 25) are constructed as single acting cylinders, wherein the at least one first and the at least one second master cylinders (14, 25) are hydraulically connected to the at least one slave cylinder (11), wherein the at least one first and the at least one second master cylinders (14, 25) are connected to the reservoir (18) via a respective check valve (19).

11. The front attachment according to claim 10, characterized in that the at least one second master cylinder (25) has a smaller piston displacement than the at least one first master cylinder (14), wherein preferably, the piston displacement of the at least one second master cylinder (25) substantially corresponds to the piston displacement of the at least one slave cylinder (11).

12. The front attachment according to one of claims 10 to 11, characterized in that the master cylinders (14, 25) are driven by a crank drive (20).

13. The front attachment according to one of claims 10 to 12, characterized in that the hydraulic cutter driving device (6) comprises two single acting first master cylinders (14) and two single acting second master cylinders (25), wherein respectively, a first master cylinder (14) and a second master cylinder (25) is hydraulically connected to a double acting slave cylinder (11), wherein on the piston side and rod side, the slave cylinders (11) are connected to the reservoir (18) via a respective pressure relief valve (17), wherein the first and second master cylinders (14, 25) are connected to the reservoir (18) via a respective check valve (19), wherein the first and second master cylinders (14, 25) are jointly driven via a crank drive (20), wherein the drive for the first master cylinder (14) and the drive for the second master cylinder (25) are 180 degrees out of phase.

14. The front attachment according to one of claims 1 to 13, characterized in that the front attachment has two cutter bars (3) and the cutter driving device (6) has at least two slave cylinders (11), wherein the cutter driving device (6) is designed in a manner such that the slave cylinder (11) drives the cutter bars (3) in opposite directions to each other.