Chopper drum for a forage harvester with knife holders adjustable to an inoperative position

Abstract

Chopper drum (22) for a field chopper (10), comprising a shaft (60) which can be set in rotation and to which a number of knife holders (62, 64) distributed around the circumference of the shaft (60) are connected, to which knife holders (56, 58) are fastened, wherein a number of the knife holders (64) are movably mounted relative to the shaft (60) and are pivotally adjustable between an operating position and an inoperative position of the chopper knives (56) fastened thereto, the adjustable knife holders (64) are coupled to a common adjusting element (70), and an adjusting shaft (66) of the adjustable knife holders (64), which is rigidly connected to the chopper knife (56), is connected to a lever (68) which extends radially inwards at one end of the chopper drum (22) and which is coupled to the adjusting element (70) which is rotatably mounted about the shaft (60) and which is in the operating position and the inoperative position relative to the shaft (60), characterized in thatthat the lever (68) is rigidly connected to the adjusting shaft (66) and is coupled to the adjusting element (70) via a slotted hole connection (72, 74).

Description

[0001] The invention relates to a chopper drum for a forage harvester according to the preamble of claim 1. Technological background

[0002] Forage harvesters are used to harvest crops from a field. These crops are picked up or cut during the harvesting process, chopped, and transferred to a transport vehicle. The chopped crops are typically used as animal feed or in biogas plants. For cutting, the crops picked up by a harvesting header are pre-compacted by pairs of pre-compression rollers and fed to a rotating chopper drum, around whose circumference a number of chopper blades are distributed. The cutting length of the chopped material is determined by the speed of the pre-compression rollers and their diameter, as well as by the spacing between adjacent chopper blades and the speed of the chopper drum.The chopper drum is usually driven by a combustion engine of the forage harvester via a purely mechanical drive train with a fixed gear ratio and thus at a constant, fixed speed, while the pre-compression rollers are driven at variable speeds by mechanical gearboxes or hydrostatic drives.

[0003] Depending on the specific intended use of the crop, different chopping lengths are desirable. For example, biogas plants generally require relatively short (e.g. 4 mm) chopped crop, while livestock feeding often requires relatively long chopping lengths (on the order of several tens of mm). Such differences in chopping length, when simply changing the speed of the pre-compression rollers to vary the chopping length, as is common practice in the state of the art, often result in the crop being literally ripped out of the harvesting header by the pre-compression rollers, as the crop is driven relatively quickly by the pre-compression rollers to achieve the long chopping length. One known solution to this problem is to reduce the speed of the chopping drum by driving it via an adjustable hydrostatic transmission (DE 196 32 977 A1) or by removing every second chopping knife (DE 2 220 826 A).The first solution is technically very complex and the second solution requires a lot of working time.

[0004] Although EP 1 407 655 A2 describes a chopper drum with adjustable chopper blades, the adjustment only serves to adapt the cutting angle of the chopper blades to the respective crop type, and all chopper blades remain in engagement with the crop regardless of their position. This chopper drum therefore cannot solve the aforementioned problem of adjusting the rotational speed and thus the cutting frequency of the chopper drum to the desired cutting length.

[0005] DE 1 204 872 A describes a chopping drum of this type, in which alternating rigid and movable blades are mounted on the chopping drum. The movable blades can be pivoted inward into a non-operating position when needed to achieve long cutting lengths. The movable blades are coupled to an adjusting disc via pivoting brackets at both ends, i.e., they are fixed by relatively fragile connections. Task

[0006] The object underlying the invention is to propose a chopper drum for a forage harvester which does not have the above-mentioned disadvantages or has them to a reduced extent. invention

[0007] The present invention is defined by the claims.

[0008] A chopper drum for a forage harvester has a rotating shaft that can be coupled to a drive and to which a number of knife holders distributed around the circumference of the shaft, to which chopping knives are attached, are connected. A portion of the knife holders (in particular, every second knife holder, viewed in the circumferential direction) are movably mounted relative to the shaft and can be adjusted between an operating position and an inoperative position for the chopping knives attached to them. In this way, the number of chopping knives engaging the crop (and thus the cutting frequency) can be adjusted relatively quickly and with little effort to the desired cutting length.

[0009] As already mentioned, the adjustable knife holders are preferably arranged circumferentially, alternating with fixed knife holders. This allows every other knife to be moved to the inoperative position to double the cutting length. However, to ensure even wear on the chopping knives, all knife holders could be made adjustable so that all chopping knives can be moved to an inoperative position alternately one after the other.

[0010] The knife holders can be mounted in a conventional manner on a drum shell coupled to the shaft. However, an open chopping drum with radially extending support discs, to which the knife holders are attached externally, can also be used, without a drum shell.

[0011] The adjustable knife holders are mounted so that they can pivot relative to the shaft about an axis extending parallel to the shaft axis.

[0012] To accelerate the adjustment of the chopping drum to the desired cutting length, the adjustable knife holders are coupled to a common adjustment element. By moving or adjusting this common adjustment element, all adjustable knife holders and the associated chopping knives can be moved together between the operating and inoperative positions.

[0013] For this purpose, an adjusting shaft of the adjustable knife holder, which is rigidly connected to the chopping knife and mounted on the chopping drum so that it can rotate about an axis parallel to the shaft axis, is rigidly connected to a lever extending radially inward at one end of the chopping drum. The lever is coupled via a slotted hole to the adjusting element, which is mounted so that it can rotate about the shaft axis relative to the shaft and can be locked in the operating and inoperative positions relative to the shaft. A rotary movement of the adjusting element pivots the lever and, with it, the adjustable knife holder between the operating and inoperative positions.

[0014] Preferably, a (fine) adjustment option is provided for the adjustable knife holders in the operating position of the chopping knives so that their position can be adapted to the wear that has occurred on the fixed chopping knives while the other chopping knives were in the non-operating position. In this case, the position of the adjustable knives can be measured at a reference point that is a defined distance from the enveloping circle of the fixed chopping knives. Such a reference point can be located, for example, on a counter-blade and the distance can be detected and displayed in particular by means of a sensor assigned to this for detecting the distance between the chopping knives and the counter-blade. By means of a screw with a fine thread or similar.The adjustment element can be adjusted by an operator, based on the display, in the operating position in such a way that the envelope circles of the fixed and adjustable chopping knives match, or this adjustment takes place automatically using a control and an actuator. Example

[0015] Two embodiments are explained with reference to the figures, whereby the reference numerals may not be used to restrict the interpretation of the claims and the embodiment according to Fig. 4 is not in accordance with the claim. It shows: Fig. 1 a forage harvester with a chopper drum in side view and in schematic representation, Fig. 2 a perspective view of a first embodiment of the chopper drum, with all chopper knives in a cutting operating position, Fig. 3 a perspective view of the chopper drum according to Fig. 3, with only half of the chopping knives in the operating position, and Fig. 4 a partial side view of a second embodiment of a chopper drum not according to the invention.

[0016] The one in the Fig. The self-propelled forage harvester 10 shown in Figure 1 is mounted on a frame 12 supported by driven front wheels 14 and steerable rear wheels 16. The forage harvester 10 is operated from a driver's cab 18, from which a crop pick-up device 20 is visible. During harvesting, crops picked up from the ground by the crop pick-up device 20, e.g., corn, grass, or the like, are fed to a chopper drum 22 by pre-compression rollers 30, 32 arranged in an intake housing 36. The chopper drum chops the crop into small pieces and feeds it to a post-accelerator 24. The crop leaves the harvester 10 to a trailer traveling alongside via a height-adjustable discharge spout 26 that can be rotated about its vertical axis.Between the chopping drum 22 and the conveyor device 24 (when harvesting maize) there extends a secondary shredding device with rollers 28, 28', through which the material to be conveyed is fed tangentially to the secondary accelerator 24.

[0017] The chopping drum 22 has a number of knives 56, 58 distributed over its circumference (cf. Fig. 2 and Fig. 3) which, during harvesting, cooperate with a rigid counter-blade 46 to cut the crop picked up by the crop pick-up device 20. A grinding device 42 serves, if necessary, to grind the chopping knives 56, 58.

[0018] It will now be Fig. 2. The chopping drum 22 comprises a central shaft 60, which is rotatably driven by a motor of the harvesting machine 10 via a pulley (not shown) and belt (not shown) and is connected to two shafts 60 arranged on both sides of the chopping drum 22 and Fig. 2 bearings (not shown) on the frame 12 of the harvesting machine 10. The shaft 60 can be continuous or consist of two shaft stubs. The shaft 60 is connected via support disks 50 to a casing 54, around the circumference of which rigid knife holders 62 with attached chopping knives 58 and adjustable knife holders 64 with attached chopping knives 56 are alternately distributed. In the axial direction, only a single chopping knife 56, 58 can be provided at a time, or several chopping knives 56, 58 can follow one another.

[0019] The rigid knife holders 62 are approximately triangular or of any other cross-section and are welded to the casing 54. The chopping knives 58 are screwed to the rigid knife holders 62 and can be replaced if necessary.

[0020] The adjustable knife holders 64 comprise bearings 78, which are also welded to the casing 54. The adjustable chopping knives 56 are screwed to brackets that are rigidly coupled to adjusting shafts 66. The chopping knives 56 can therefore also be replaced if necessary. The adjusting shafts 66 extend axially and parallel to the shaft 60 and are mounted on the bearings 78 so as to be freely rotatable about their longitudinal axes. The adjusting shafts 66 are Fig. 2 and Fig. 3 ends shown on the left are rigidly connected to levers 68 which extend approximately radially inwards and are provided with elongated holes 74 near their inner ends. Cylindrical pins 72 engage in the elongated holes 74 and are firmly connected to a plate-shaped, round adjusting element 70. The adjusting element 70 is mounted so as to be rotatable about the longitudinal axis of the shaft 60 relative to the support disk 50, on the outside of which it also extends radially, is concentric with the shaft 60 and can be locked in the respective rotational position, for which purpose, for example, a screw penetrating an elongated hole 76 in the adjusting element 70 can rest with its head on the adjusting element 70 and can engage with its thread in a thread in the support disk 50.In a more sophisticated embodiment, an actuator (not shown), particularly electrically or hydraulically operated, can also be used to adjust the adjustment element 70 and can be controlled by a controller 52 via an operator interface 98. The supply of operating fluid to the actuator and a feedback of a sensor value regarding the current position of the adjustment element 70 can be effected via sliding contacts attached to the front of the chopping drum 22 or engaging there.

[0021] As shown by the Fig. 2 and Fig. 3, the adjusting element 70 allows all chopping knives 56 of the adjustable knife holders 64 to rotate together around the adjusting shafts 66 and to switch between the Fig. 2 and the operating position shown in the Fig. 3. In the operating position, all chopping knives 56, 58 are engaged with the crop and chop it up. In the inoperative position, only the chopping knives 58 of the rigid knife holders 62 are engaged with the crop and chop it up, i.e., the number of effective chopping knives 58 has been halved and the cutting length doubled, while the chopping knives 56 attached to the adjustable knife holders 64 do not noticeably cut the crop, but at most convey it further.

[0022] After the chopping drum 22 has been operated for a longer period of time with the adjustable chopping knives 56 in the inoperative position, the rigid chopping knives 58 may have become somewhat worn, in particular after a grinding process carried out by means of the grinding device 42 on only the rigid chopping knives 56. In order to ensure an identical enveloping circle of all chopping knives 56, 58, the (manually or automatically performed) adjustment of the adjusting element 70 into the operating position can be carried out based on a distance sensor (not shown) assigned to the counter-blade 46, which can be based on any desired (e.g. inductive, acoustic or optical) measuring principle.

[0023] In the second embodiment not according to the invention according to Fig.4, elements identical or having the same effect as the first embodiment are identified by the same reference numerals. The essential difference is that the chopping knives 56 of the adjustable knife carrier 64, which are adjustably mounted between the operating and inoperative positions, are not pivoted, as in the first embodiment, but are displaced radially inwards from the operating position into the inoperative position. For this purpose, the chopping knives 56 are fastened to a displacement element 66', which is supported so as to be displaceable in the radial direction relative to bearings 78 welded to the casing 54 or fastened there in some other way, e.g. with pins 80 with protruding heads guided in an elongated hole in the bearing 78 or the displacement element 66'. The adjustment is also effected via an adjustment element 70, which is drive-coupled to the displacement element 66' and the adjustment element 70 by levers 68' pivotably coupled on both sides.

[0024] In this embodiment, it is considered advantageous that the cutting forces (exerted tangentially on the chopping knives 56) are not diverted via the lever 68, but are transmitted to the casing 54 via the sliding element 66' and the bearing 78, while the levers 68 only serve to adjust the chopping knives 56 and do not have to absorb any cutting forces. Furthermore, the precise adjustment of the adjusting element 70 and thus of the sliding element 66' is less critical, since one or both of them (or an element connected to them, such as the pin 80) can be moved against a stop 82 on the bearing 78 or the support disc 50 in the operating position. In this position, the chopping knives 56 and 58 can then be correctly positioned in the tangential direction relative to the counter-blade 46 or another reference point and screwed tightly to the knife holders 62 or the sliding element 66'.Temporary wear of the non-adjustable chopping knives 58 when the adjustable chopping knives 56 are in the non-operating position only insignificantly influences the position of the envelope curve of the chopping knives 58 due to the approximately tangential orientation of the chopping knives 58 (and 56) and can, if necessary, be compensated for by a grinding process using the grinding device 42.

Claims

[1] Chopper drum (22) for a forage harvester (10), comprising a shaft (60) which can be set in rotation and to which a number of knife holders (62, 64) distributed around the circumference of the shaft (60) are connected, to which knife holders (56, 58) are fastened, wherein a number of the knife holders (64) are movably mounted relative to the shaft (60) and are pivotally adjustable between an operating position and an inoperative position of the chopper knives (56) fastened thereto, the adjustable knife holders (64) are coupled to a common adjusting element (70), and an adjusting shaft (66) of the adjustable knife holders (64), which is rigidly connected to the chopper knife (56), is connected to a lever (68) which extends radially inwards at one end of the chopper drum (22) and which is coupled to the adjusting element (70) which is rotatably mounted about the shaft (60), can be fixed in the operating position and the inoperative position relative to the shaft (60), characterized bythat the lever (68) is rigidly connected to the adjusting shaft (66) and is coupled to the adjusting element (70) via a slotted hole connection (72, 74). [2] Chopping drum (22) according to claim 1, wherein the adjustable knife holders (64) are arranged in the circumferential direction alternating with rigid knife holders (62). [3] Chopping drum (22) according to claim 1 or 2, wherein the knife holders (62, 64) are attached to a drum shell (54) coupled to the shaft (60). [4] Chopping drum (22) according to one of the preceding claims, with an adjustment possibility for the radial position of the adjustable knife holders (64) in the operating position of the chopping knives (56). [5] Self-propelled or towed forage harvester (10) with a chopper drum (22) according to one of claims 1 to 4.

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