METHOD FOR OPERATING A ROUND BALE PRESS

Description

[0001] The present invention relates to a method according to the preamble of claim 1 and a round baler according to the preamble of claim 13.

[0002] Round balers are used in agriculture to pick up crops such as hay or straw from the ground and compress them into round bales, which can then be wrapped with binding material. The binding material used can be string, nets or (in the case of grass, for example) film, although the latter can also be applied outside the baler in a separate bale wrapping device. The crop is first picked up from the ground (normally by a pick-up) and then transferred to a conveyor rotor or cutting rotor, which transports the crop via a feed channel to the bale forming chamber or pressing chamber, where the actual pressing takes place. There, pressing elements act on the crop, which also act as conveying elements and create a circular movement of the crop.In balers with a variable chamber, the effective size of the chamber is adapted to the increasing amount of crop, with at least one continuously rotating baling element defining a predominant part of the baling chamber. The baling element can be designed, for example, as a bar-and-chain conveyor with rotating chains and bars running between them, or it can have one or usually several baling belts. It is guided over a plurality of guide or tensioning rollers, with typically at least one tensioning roller being arranged on a movable tensioning rocker. The tensioning rocker is subjected to a force either via spring elements or actuators, which influences the tension in the baling element and thus also the pressing pressure on the crop bale.

[0003] When crop is fed into the bale chamber and the bale grows within the bale chamber, the tensioning arm is deflected so that a larger portion of the endless baling element can surround the bale chamber. In the case of a hydraulic actuator, hydraulic fluid is displaced from the actuator. The position of the tensioning arm can be monitored by sensors, and from this, the current size of the crop bale or the bale chamber can be determined. This can alert the driver of a tractor pulling the round baler that the actual diameter of the bale is approaching a predetermined target diameter. The driver can then stop the tractor / trailer combination, interrupting the crop feed. The formed bale can now be wrapped with binding material and ejected, after which the tractor / trailer combination starts up again and the formation of the next bale begins. If the target diameter cannot be achieved, e.g.At the end of a field, the driver can also start the tying process manually. The finished bale will then be smaller than the target diameter. Irrespective of this, however, there is the problem that the actual diameter achieved depends on when the crop feed is interrupted, for example, when the driver stops the tractor / trailer combination. However, the driver can hardly estimate the right time for this, e.g. due to locally varying crop quantities and qualities. This means that the individual crop bales will have different diameters, which can lead to problems, for example, during loading and transport.

[0004] US 2011 / 0023442 A1 and US 2019 / 0098837 disclose prior art round balers with clamping arms. EP 3 298 881 A1 also features a control function for varying the baling pressure.

[0005] The object of the invention is to enable the production of round bales of as consistent a size as possible.

[0006] The object is achieved by a method for operating a round baler, having the features of independent patent claim 1 and a round baler having the features of independent patent claim 13. Advantageous embodiments can be found in the dependent claims.

[0007] For this purpose, a method for operating a round baler is provided, wherein the round baler has a pressing device by means of which a pressing chamber for forming a crop bale can be at least partially defined, wherein a pressing pressure exerted by the pressing device on the crop bale can be changed by at least one actuator, feed means for feeding crop to the pressing chamber, a measuring device with which an actual diameter of the crop bale can be determined at least indirectly, and a binding unit for a binding process of the crop bale during an interruption of the crop feed.

[0008] The round baler is designed to press agricultural crops into (round) bales. It can be self-propelled or designed to be pulled by a tractor. The agricultural crop can in particular be stalk crops such as grass, straw or hay. The actual pressing process takes place within the baling chamber by the pressing device. The baling chamber, in which the bale is formed and compressed, is at least partially limited or defined by the pressing device. This is usually a variable baling chamber. The pressing device can have one or more pressing elements that are movably arranged on a frame. The pressing pressure that the pressing device exerts on the crop bale can be varied by at least one actuator, which can optionally be part of the pressing device.The baling pressure is usually not completely constant everywhere and, for this reason alone, cannot be precisely adjusted. However, the baling pressure can at least be increased or decreased by the actuator, meaning that its quality can at least be specifically influenced. It is understood that a higher baling pressure generally leads to greater compaction of the crop. The actuator can, in particular, be designed as a linear actuator. It can be operated electrically, hydraulically, or pneumatically, for example.

[0009] The feeding devices serve to feed the crop into the baling chamber. This can include, for example, a pick-up that collects the crop from the ground, as well as a conveying device, e.g., a conveyor rotor that conveys the crop toward the baling chamber. Instead of a simple conveyor device, or in addition to one, a cutting device can be provided that not only conveys the crop but also cuts it. A feed channel, through which the crop flows before reaching the baling chamber, can also be considered a (passive) feeding device.

[0010] The measuring device can be used to at least indirectly determine the actual diameter of the crop bale. This means that the measuring device provides at least one value or parameter from which the actual diameter can be clearly determined. The measuring device can have at least one sensor that provides a measured value from which the actual diameter can be determined. The term "diameter" should not be strictly interpreted here to mean that the crop bale must have a perfectly circular cross-section. Slight deviations from the circular shape are known to be normal; in this respect, the "diameter" can be defined as the average dimension of the crop bale.

[0011] The tying unit is used to initiate a tying process in which the crop bale, after it has been formed, is provided with binding material, e.g. with at least one piece of string, net or film. The tying unit can have a binding material holder for a supply of binding material (typically a roll of binding material) and a feed unit for feeding binding material to the bale chamber. The tying process, in which the binding material is normally wrapped around the bale while it is rotated in the bale chamber, is carried out during an interruption in the crop feed. This means that when the crop bale is considered ready, no more crop is added and the tying process can begin. Instead of an interruption, one could also speak of a stop in the crop feed, although the crop feed continues again to form the next bale.Interrupting the crop supply also stops bale formation in that no more crop is added to the crop bale.

[0012] According to the invention, during the interruption of the crop feed, a size adjustment is carried out by carrying out at least one comparison between the actual diameter and a target diameter specified at least as a target diameter range, and at least one pressure adjustment, in which the baling pressure is automatically adjusted depending on at least one comparison in order to adjust the actual diameter to the target diameter. The target diameter is predefined, ie it is set before the start of the size adjustment, e.g. by an input from a user of the round baler. It is normally specified as a single value. Alternatively, it can also be defined, less precisely, as a target diameter range that is characterized by a lower limit and an upper limit.You could also say that a comparison is made between the actual diameter on the one hand and (exactly) a target diameter or a target diameter range on the other. The aim of the process is for the finished, tied crop bale to have this target diameter as exactly as possible. To do this, a size adjustment is carried out while the crop feed is interrupted, i.e. when no more crop is being added to the bale. Ideally, the actual diameter would correspond to the target diameter at this point in time, but in practice this is usually not the case for various reasons. As part of the size adjustment, at least a comparison is made between the target diameter and the actual diameter, i.e. it is determined whether the crop bale is currently too big, too small or possibly exactly the right size. Furthermore, at least one pressure adjustment is carried out.The pressing pressure is automatically adjusted depending on at least one comparison. The adjustment is made "depending on" at least one comparison, which includes the possibility that the pressing pressure may remain unchanged depending on the comparison result. Otherwise, the pressing pressure is automatically adjusted to bring the actual diameter closer to the target diameter, thus reducing the difference between the two. Ideally, the difference should be zero.

[0013] The basic idea is that the bale can still expand or be compressed, at least within certain limits, after the actual bale formation with crop feed has already ended. The expansion or compression can be brought about by adjusting the baling pressure. Since the amount of crop in the bale no longer changes, this results in a change in the baling density, which is normally minor, has no practical disadvantages and is not noticeable. Without the size adjustment, diameter differences of a few centimeters would arise, which are visible to the naked eye and would also make handling the crop bales more difficult, for example during loading or transport. The aforementioned process steps (in particular comparison and pressure adjustment) are preferably carried out by the round baler or by a control unit that is connected to the at least one actuator and the measuring device in a signal-transmitting manner.This control unit can be fully or partially integrated into the round baler, but it can also be fully or partially located outside of it, e.g. in a tractor that pulls the round baler.

[0014] Preferably, during at least one pressure adjustment, the baling pressure is reduced if the actual diameter is at least smaller than the target diameter. This applies in particular to the beginning of the size adjustment. In this state, it can be assumed that the crop bale can only expand if the currently acting baling pressure is reduced. "At least smaller than the target diameter" means that a more stringent criterion can also be checked here, e.g., whether the actual diameter is below the target diameter by a predefined tolerance value (mentioned further below). Likewise, it is preferred that during at least one pressure adjustment, the baling pressure is increased if the actual diameter is at least larger than the target diameter. This also applies in particular to the beginning of the size adjustment, where it can be assumed that the crop bale can only be compressed by increasing the baling pressure.Here, too, it is possible to optionally check whether the actual diameter is above the target diameter by the predefined tolerance value.

[0015] The baling device advantageously has at least one endless baling element which can be driven in rotation relative to a frame and which is guided over at least one tensioning roller which is adjustable relative to the frame and which is acted upon by at least one actuator to change the baling pressure. The frame forms the basic structure of the round baler and gives it overall stability. Running wheels are also attached to the frame via a suitable suspension, as is a drawbar in the case of a towed design. In addition, the frame typically has a housing which shields the internal parts, namely the baling chamber, from the outside. The endless baling element can in particular be designed as one or more endless baling belts or belts, but alternatively also, for example, as a chain and bar conveyor. In any case, it can be driven in rotation, for which purpose it can be provided, for example, with a plurality of guide rollers orTension rollers, at least one of which is connected to a drive. Each guide or tension roller serves on the one hand to guide the baling element, but on the other hand usually also to maintain a (tensile) tension in the baling element. At least one tension roller is arranged so that it can be adjusted relative to the frame, i.e. it is not only rotatable, but can also be adjusted as a whole relative to the frame. By adjusting the tension roller(s), the endless baling element is given more or less free length, within which the baling chamber can be defined. A change in the size of the crop bale is therefore only possible by adjusting the tension roller(s), which is why the actual diameter can be determined from the position of the tension roller(s).A specific baling pressure exerted by the baling element on the crop bale corresponds to a specific tensile stress in the baling element, which in turn corresponds to a specific force between the tension roller and the baling element. If the tension roller is subjected to force – directly or indirectly – by at least one actuator, this results in a specific baling pressure. There is a clear (albeit generally non-linear) relationship between force and baling pressure. In addition to influencing the baling pressure, the at least one actuator can also adjust the tension roller, which corresponds to a change in the size of the baling chamber or its actual diameter.

[0016] In connection with the embodiment described above, it is preferred that the measuring device determines the current position of at least one tensioning roller. Typically, the tensioning roller is arranged on a tensioning rocker which is pivotally connected to the frame. The current position of the tensioning roller can therefore be determined, for example, via a sensor which determines the pivoting angle of the tensioning rocker. Since the pressing element generally has negligible extensibility, there is a clear relationship between the position of the at least one tensioning roller and the actual diameter. In the case of several independently movable tensioning rollers, the relationship may be more complicated; however, here too, the actual diameter can be clearly determined from the positions of the individual tensioning rollers. An actuator, which can be designed, for example, as a linear actuator, acts between the frame and the tensioning rocker and can adjust orInfluence the pressing pressure by applying force to the clamping arm.

[0017] According to one embodiment, the size adjustment is carried out at least partially during the binding process. Normally, the binding material is wrapped around the crop bale in several layers. After the binding process has been completed, these layers of binding material generally form a shell that defines the actual diameter, i.e. the crop bale can no longer expand. Likewise, any compression of the crop bale developed in this way would not be permanent. However, as long as the binding material has not yet been fully applied during the binding process (e.g. only a portion of the total planned layers), the crop bale can still expand together with the binding material and it is also possible to compress the crop bale together with the binding material and to wrap the subsequent layers accordingly more tightly. Size adjustment during the binding process is advantageous in that it can save time.In some circumstances, energy can also be saved because, for example, a stronger compression only needs to be maintained for a short time before it is secured by wrapping the crop bale.

[0018] Alternatively or additionally, the size adjustment can be performed at least partially before the start of the binding process. This can be particularly useful if the initially measured actual diameter deviates significantly from the target diameter, or if the binding material used is not very stretchable or deformable, so that adjustment is only possible to a limited extent once the binding material has been applied to the crop bale. In both cases, it can be useful to perform a preliminary adjustment of the actual diameter.

[0019] Under the best of circumstances, it would be conceivable to carry out just one comparison and one pressure adjustment in order to achieve the target diameter. However, this would require that the compression or expansion behavior of the crop bale is completely predictable. Experience has shown, however, that this behavior differs even for one and the same type of crop, for example depending on the location and time of harvest. Therefore, such a one-off adjustment will generally not produce optimal results. It is therefore preferable to carry out several comparisons one after the other and, depending on these, several pressure adjustments. This means that an initial comparison and (if necessary) an initial pressure adjustment are carried out. After some time (e.g. a few seconds), a second comparison is carried out, which allows the effect of the initial pressure adjustment to be monitored to a certain extent.If necessary, a second pressure adjustment is performed, etc. As explained below, the second pressure adjustment does not have to be based exclusively on the second comparison, but could also include the first comparison or the first and second measured actual diameters. The intervals between the individual comparisons can be varied; a quasi-continuous pressure adjustment, in which the comparisons follow one another without a significant time gap, is also conceivable.

[0020] There are various options for initiating the tying process. According to one design, the tying process begins automatically as soon as an interruption in the crop feed is detected. Generally, the crop feed must be interrupted to prevent the tying material or the tying unit from becoming contaminated or blocked by loose crop. The tying process can then be triggered immediately, for example, by the round baler or a control unit of the round baler as soon as it detects the interruption. Of course, the tractor driver can also trigger the tying process manually.

[0021] The interruption of the crop supply can be detected in different ways. Regardless of whether the round baler is self-propelled or trailed, the crop supply is interrupted when the round baler comes to a standstill, although it is possible that the crop supply may continue for a certain time if the feeding means are still feeding when the round baler is at a standstill. In this case, a fixed time delay could be provided. In any case, the round baler could have a speed sensor and the interruption of the crop supply could be detected by the speed sensor when the round baler comes to a standstill. Alternatively or additionally, the round baler could have a feed sensor for detecting the crop supply, by means of which the interruption of the crop supply is detected.Such a sensor could detect whether the feeding means are still moving, whether there is still crop in the feed channel (with a light barrier, ultrasonic sensors, etc.) or the like.

[0022] If it is a trailed round baler, it is coupled to a tractor during the process, in other words a tractor or tractor unit, i.e. generally a powered vehicle suitable for pulling the round baler. In addition to the pure tractive power transmission, energy for various systems of the round baler is often also transmitted from the tractor, e.g. via a drive shaft and / or an electrical, pneumatic and / or hydraulic connection. Finally, signals can also be transmitted from the tractor, either wirelessly or wired, for example via ISOBUS. In this case, the round baler can detect an interruption in the crop feed even without its own sensors, based on a signal it receives from the tractor. The signal can indicate, for example, that the tractor has stopped. When the tractor stops, the crop feed is inevitably interrupted.

[0023] On the one hand, the current actual diameter can be used as a criterion for determining whether the baling pressure should be changed. However, depending on the type and condition of the crop, the crop bale may react to a change in baling pressure with a certain delay. This means that even if a certain actual diameter can be achieved with a certain baling pressure, this actual diameter may not be accepted "immediately" but only after a certain period of time. This means that the current baling pressure could, for example, be suitable for achieving the target diameter, but a current measurement of the actual diameter would still result in a deviation because the crop bale is in the process of expanding or compressing. This problem can be addressed by determining the actual diameter several times in succession and using this to determine a temporal change VD, e.g. VD = DI t 1 − DI t 0 , where DI(t0)and DI(t1) the actual diameters at different times t0, t1represent. With at least one pressure adjustment, the pressing pressure is adjusted at least partially as a function of the change over time. This means that not only the actual diameter is taken into account, but also its change. As long as the actual diameter changes at least qualitatively correctly (i.e. reduced if the actual diameter is too large or increased if the actual diameter is too small), the current pressing pressure has the intended effect. If this is the case, the pressing pressure can be maintained even though the target diameter has not yet been reached. It could also be determined by how much the actual diameter has changed within a certain period of time and whether, under these circumstances, the target diameter can be expected to be reached soon. If not, the pressing pressure can be changed.It would even be conceivable to detect an excessively rapid approach to the target diameter, which could lead to the actual diameter changing beyond the target diameter, thus overshooting the target. In this case, the pressing pressure could be reduced during compression or increased during expansion to prevent such an "overshoot."

[0024] If the size adjustment is initiated before the tying process, there are different options for starting the tying process. The tying process could start when a predefined delay time has elapsed since the interruption of the crop feed. However, a more "flexible" criterion can also be defined. According to one embodiment, the tying process is initiated after the start of the size adjustment, as soon as the actual diameter deviates from the target diameter by at most a predefined tolerance value. This means that the size adjustment starts and the actual diameter is compared (if necessary repeatedly) with the target diameter. A tolerance value is predefined, for example, a few centimeters or millimeters. If the deviation from the actual diameter THE from the target diameter DS maximum tolerance value TW corresponds, so DI − DS < = TW , This is considered sufficient adjustment to initiate the binding process. Depending on the tolerance value and the initial actual diameter, it is also possible, for example, for the binding process to start immediately after the first comparison. Defining a tolerance value is not necessary if the target diameter is specified as the target diameter range, since this already includes a tolerance.

[0025] An advantageous embodiment provides that after the start of the size adjustment, the binding process is started if at least one pressure adjustment leads to a change VD of the actual diameter, the amount of which does not exceed a predefined threshold SW corresponds, so VD < = SW .

[0026] The threshold value could also be defined as zero, or with another (positive) value that characterizes a negligible change. Normally, a pressure adjustment should lead to a change in the actual diameter, at least after a certain time that the crop needs to react to the pressure adjustment. However, it could be that the pressure change leads to no or only a minimal change in the actual diameter, either because the crop is compressed to the maximum extent possible within the capabilities of the baling device or because it is fully expanded. The former could be the case if significantly too much crop has been picked up, so that the actual diameter can no longer be reduced to the target diameter. The latter could be the case, for example, if significantly too little crop can be picked up at the end of the field to form a bale of normal size.In this case, the crop bale might not be able to expand to the desired diameter even with minimal baling pressure. In both cases, it would be pointless to delay the tying process any further. Therefore, the tying process is initiated even if the desired diameter has not yet been reached.

[0027] The object is further achieved with a round baler having the features of independent patent claim 13. The round baler has a pressing device by means of which a pressing chamber for forming a crop bale can be at least partially defined, wherein a pressing pressure exerted by the pressing device on the crop bale can be changed by at least one actuator, feed means for feeding crop to the pressing chamber, a measuring device with which an actual diameter of the crop bale can be determined at least indirectly, and a binding unit for binding the crop bale during an interruption in the crop feed.

[0028] According to the invention, the round baler is designed to carry out a size adjustment during the interruption of the crop supply by carrying out at least one comparison between the actual diameter and a target diameter specified at least as a target diameter range, and at least one pressure adjustment in which it automatically adjusts the baling pressure depending on at least one comparison in order to adjust the actual diameter to the target diameter.

[0029] The terms mentioned have already been explained above with reference to the method according to the invention and will therefore not be explained again. Advantageous embodiments of the round baler according to the invention correspond to those of the method according to the invention.

[0030] The round baler preferably has a control unit. The control unit can be connected to the at least one actuator and the measuring device in a signal-transmitting manner. The connection can be established wired and / or wirelessly. Functions of the control unit can be implemented at least partially in software.

[0031] The control unit is configured to perform a size adjustment during the interruption of the crop feed by performing at least one comparison between the actual diameter and a target diameter specified at least as a target diameter range, as well as at least one pressure adjustment, in which it automatically adjusts the pressing pressure depending on at least one comparison in order to adjust the actual diameter to the target diameter. It is understood that the control unit performs the pressure adjustment by means of the at least one actuator if it is connected to it in a signal-transmitting manner.

[0032] The terms mentioned have already been explained above with reference to the method according to the invention and are therefore not explained again.

[0033] The invention is described below with reference to figures. The figures are merely exemplary and do not limit the general inventive concept. They show Fig. 1 shows a sectional view of a roller baler according to the invention; Fig. 2 shows a flowchart of a first embodiment of a method according to the invention; and Fig. 3 shows a flowchart of a second embodiment of a method according to the invention.

[0034] Fig. 1shows a roller baler 1 according to the present invention. This is intended to be pulled by a tractor or a tractor (not shown). In addition to the running wheels 2 on which the roller baler 1 stands, a pressing device 10 is arranged on a frame 8 of the roller baler 1. This pressing device can form a pressing chamber 18 of variable size for forming a crop bale 50. In the direction of travel F, a pick-up 3 can be seen on the front of the frame 8. This pick-up 3 serves to pick up crop such as straw, hay or grass from the ground. From the pick-up 3, the crop reaches a cutting rotor 4, which grasps the crop, cuts it up and transports it further, against the direction of travel F and slightly upwards, through a conveyor channel 5. The pick-up 3 and the cutting rotor 4 (which could also be designed as a simple conveyor rotor) serve to feed the crop to the pressing chamber 18. By means of aThe feed sensor 23 arranged on the feed channel 5 can determine whether crop material is currently being conveyed in the feed channel 5.

[0035] The pressing device 10 has three pressing rollers 11 and at least one pressing belt 12 (possibly also several pressing belts arranged side by side perpendicular to the plane of the drawing), which together define the pressing chamber 18. The pressing rollers 11 and the pressing belt 12 cause the crop bale 50 to rotate and simultaneously compress the crop, which can already be pre-compacted in the feed channel 5. The pressing belt 12 is guided over a plurality of stationary, rotatable guide rollers 13 and over two tensioning rollers 14, which are mounted on a tensioning rocker 15, which in turn is pivotally arranged on the frame 8. Since the pressing belt 12 has a practically constant length and must be constantly kept under tension, the tensioning rocker 15 must be deflected in order to compensate for different sizes of the crop bale 50. If the crop bale 50 is small or the baling chamber 18 is empty, the tensioning arm 15 is pivoted downwards.If the crop bale 50 is large, the tensioning arm 15 is pivoted upward. There is a clear relationship between the actual diameter of the crop bale 50 and the position of the tensioning arm 15, which can be measured using a measuring device, in this case a position sensor 17. The tensioning arm 15 is connected to the frame 8 via an actuator 16 and can be actively pivoted by this actuator 16 or subjected to a force of varying intensity in a specific position. This, in turn, influences the (tensile) tension in the baling belt 12 and the pressing pressure acting on the crop bale 50.

[0036] Once the crop bale 50 has been completed, it is wrapped with a binding material (not shown here) (e.g., a net) within the baling chamber 18 before it is finally ejected rearwardly against the direction of travel F. For the binding process, the binding material is grasped by a feed spout 21 of a binding unit 20, which guides the binding material through a gap 19 formed between two pressing rollers 11 up to the crop bale 50. From there, the binding material is pulled between the crop bale 50 and the adjacent pressing roller 11 by the rotation of the latter, adhering to the crop bale 50 and then being wrapped around it by the latter's rotation.

[0037] The round baler 1 has a control unit 25, which can also be partially implemented in software. This control unit is connected to the sensors 17, 22, 23 and to the actuator 16 for signal transmission. As an alternative to being located inside the round baler 1, the control unit 25 could also be located entirely or partially outside, e.g., in the tractor or in a portable device.

[0038] The user (in this case, the tractor driver) can normally specify at least three parameters for producing the crop bale 50: the baling pressure, a target diameter DS for the crop bale 50, and the number of layers of binding material. The target diameter DS is a single value in this example. Alternatively, it could also be a target diameter range. Other parameters are also possible, e.g., varying the baling pressure, which can produce a less dense core and a denser shell. The position sensor 15 monitors the actual diameter, and a warning is given to the driver when the target diameter is about to be reached. The driver can then interrupt the crop feed by stopping the tractor and round baler 1 combination. The binding process can now begin. Due to various circumstances, the crop bale often has an actual diameter THE which differs from the target diameter DS This can be corrected with a first embodiment of a method according to the invention, which is shown in the flow chart in Fig. 2 The process is controlled by the control unit 25 of the round baler 1.

[0039] After starting the process, a check is carried out in step S100 to determine whether the crop feed has been interrupted. There are various possibilities for this. For example, the control unit 25 can receive a signal S from the tractor, indicating that it has stopped. Alternatively, the control unit 25 can determine via the speed sensor 22 that it has stopped itself. Both of these mean that no further crop can be picked up and fed to the baling chamber 18. Finally, the feed sensor 23 can also directly determine whether any crop is still being fed to the baling chamber 18. This check is repeated until the crop feed is interrupted. The binding process is then started in step S110, and the actual diameter is measured in step S120. THE In the following step S130, the actual diameter is compared with the target diameter. If the actual diameter differs by a maximum of one tolerance value TWdiffers from the target diameter, i.e. DI − DS < = TW , the process continues directly with step S170. If the actual diameter is smaller than the target diameter by more than the tolerance value, i.e. DS − DI > TW , In step S140, the pressing pressure is reduced before the method continues with step S170. If the actual diameter is larger than the target diameter by more than the tolerance value, i.e. DI − DS > TW , In step S150, the baling pressure is increased and the method continues with step S170. In step S170, a check is made to determine whether the binding process has already been completed. If so, the method ends; if not, it returns to determining the actual diameter in step S120. Thus, the actual diameter is repeatedly checked and the baling pressure is adjusted, with an attempt always being made to adjust the actual diameter to the target diameter. Depending on the binding material and the number of layers, it might be useful not to check the end of the binding process in step S170, but rather to check whether so much binding material has already been wrapped around the crop bale 50 that the actual diameter can no longer be influenced by the baling pressure.

[0040] Fig. 3 shows a second, more complex embodiment of the method according to the invention, wherein the same steps have the same numbers as in Fig. 2If the interruption of the crop supply is detected in step S100, a change is made in step S105 VD of the actual diameter is initialized with the value zero. The method then proceeds directly to step S120 without starting the binding process. In a variant of the method, step S110 could also be inserted, which would eliminate the steps S155, S160, S185, S190, and S195 described below.

[0041] In step S125, following step S120, a check is made to determine whether a previous actual diameter has already been stored. If this is not the case, the method continues with step S130, where the comparison between the actual diameter and the target diameter described above is again performed. However, the pressure increase in step S140 is only performed if a preceding comparison in step S135 has shown that the change VD of the actual diameter has not been exceeded by at least a threshold value. SW is below zero, so VD + SW > = 0 .

[0042] This would be the case with the initialization described above, so that step S140 would be carried out first. The threshold SW is normally positive, but could also be zero. If the actual diameter differs by at most the tolerance value TWdeviates from the target diameter, a check is made in step S155 to determine whether the binding process has already begun. If not, the binding process is started in step S160; if yes, step S160 is skipped and the method continues with step S170. The pressure reduction in step S150 is only carried out if it was determined in a preceding step S145 that the change in the actual diameter is smaller than the threshold value SW, i.e. VD < SW .

[0043] This would also be the case with the initialization mentioned.

[0044] If it is determined in step S170 that the binding process is not yet complete, the last determined actual diameter is stored in step S175 and the method returns to step S120. Since a previous actual diameter is now stored, the query in step S125 leads to a positive result and the method continues with step S180, where the change in the actual diameter is stored as the difference between the current actual diameter and the actual diameter. DI(t1) and the previous actual diameter DI(t0) is calculated. VD = DI t 1 − DI t 0 ,

[0045] In step S185, a check is made to determine whether the binding process has already begun. If so, the method proceeds directly to step S130. If not, a check is made in step S190 to determine whether the change is at most equal to the threshold value, i.e. VD < SW .

[0046] If this is the case, the binding process is started in step S195. If not, step S195 is skipped and the method continues directly with step S130. Since a change VD that is generally different from zero has now been calculated, it may be the case, for example, that in step S130 it is determined that the actual diameter is too small, but in step S135 it is determined that the change is clearly positive, i.e. that the crop bale 50 was last expanded. In this case, there is no (further) pressure reduction in step S140, but this step is skipped. Accordingly, in step S130 it may be determined that the actual diameter is too large, while in step S145 it is determined that the change is clearly negative, i.e. that the crop bale 50 was last compressed. In this case, there is no (further) pressure increase in step S150, but the method continues directly with step S170.The check in steps S135 and S145 takes into account that the comparisons in step S130 and the pressure adjustments in steps S140 and S150 may, under certain circumstances, follow one another more quickly than the crop bale 50 can react. This means that a certain inertia of the crop is taken into account. Steps S135 and S145 can be omitted if the comparisons according to step S130 follow one another at such a large time interval that it can be assumed that the crop bale 50 can react fully to changes in the baling pressure in the meantime.

Claims

1. Method for operating a round baler (1) comprising a pressing device (10), by means of which a pressing chamber (18) for forming a crop bale (50) can be at least partially defined, wherein a pressing pressure exerted by the pressing device (10) on the crop bale (50) can be varied by at least one actuator (16), feed means (3, 4) for feeding crop to the pressing chamber (18), a measuring device (17) by means of which an actual diameter (DI) of the crop bale (50) can be at least indirectly determined, and a binding unit (20) for a binding process of the crop bale (50) during an interruption of the crop feed, characterized in that during the interruption of the crop feed, a size adjustment is carried out by at least one comparison (S130) being made between the actual diameter (DI) and a target diameter (DS) specified at least as a target diameter range, as well as at least one pressure adjustment (S140, S150), in which the pressing pressure is automatically adjusted according to the at least one comparison in order to adjust the actual diameter (DI) to the target diameter (DS).

2. Method according to claim 1, characterized in that in at least one pressure adjustment (S140, S150) the pressing pressure is reduced if the actual diameter (DI) is smaller than the target diameter (DS) and / or the pressing pressure is increased if the actual diameter (DI) is larger than the target diameter (DS).

3. Method according to any of the preceding claims, characterized in that the pressing device (10) has at least one endless pressing element (12) which can be driven in rotation relative to a frame (8) and which is guided over at least one tensioning roller (14) which is arranged adjustably relative to the frame (8) and is acted upon by the at least one actuator (16) to change the pressing pressure.

4. Method according to any of the preceding claims, characterized in that the measuring device (17) determines a current position of at least one tensioning roller (14).

5. Method according to any of the preceding claims, characterized in that the size adjustment is carried out at least partially during the binding process.

6. Method according to any of claims 1 - 4, characterized in that the size adjustment is carried out at least partially before the binding process begins.

7. Method according to any of the preceding claims, characterized in that the binding process is started automatically (S110) as soon as the interruption of the crop feed is detected (S100).

8. Method according to any of the preceding claims, characterized in that the round baler (1) has a speed sensor (22) and / or a feed sensor (23) for detecting the crop feed and the interruption of the crop feed is detected (S100) by means of the speed sensor (22) on the basis of a standstill of the round baler (1) and / or by means of the feed sensor (23).

9. Method according to any of the preceding claims, characterized in that the round baler (1) is coupled to a tractor and detects (S100) the interruption of the crop feed on the basis of a signal (S) which it receives from the tractor.

10. Method according to any of the preceding claims, characterized in that the actual diameter (DI) is determined several times in succession (S120), a temporal change (VD) is determined (S180) therefrom and, in at least one pressure adjustment (S140, S150), the pressing pressure is adjusted at least partially on the basis of the temporal change (VD).

11. Method according to any of the preceding claims, characterized in that after the size adjustment has begun, the binding process is started (S160) as soon as the actual diameter (DI) deviates from the target diameter (DS) by at most a predefined tolerance value (TW).

12. Method according to claim 10, characterized in that after the size adjustment has begun, the binding process is started (S195) if at least one pressure adjustment (S140, S150) has led to a temporal change (VD) in the actual diameter (DI), the amount of which corresponds at most to a predefined threshold (SW).

13. Round baler (1) comprising a pressing device (10), by means of which a pressing chamber (18) for forming a crop bale (50) can be at least partially defined, wherein a pressing pressure exerted by the pressing device (10) on the crop bale (50) can be varied by at least one actuator (16), feed means (3, 4) for feeding crop to the pressing chamber (18), a measuring device (17) by means of which an actual diameter (DI) of the crop bale (50) can be at least indirectly determined, and a binding unit (20) for a binding process of the crop bale (50) during an interruption of the crop feed, characterized in that the round baler (1) is designed to carry out a size adjustment during the interruption of the crop feed by making at least one comparison (S130) between the actual diameter (DI) and a target diameter (DS) specified at least as a target diameter range, as well as at least one pressure adjustment (S140, S150), in which it automatically adjusts the pressing pressure according to at least one comparison in order to adjust the actual diameter (DI) to the target diameter (DS).

14. Round baler according to claim 13, characterized in that it has a control unit (25) which is connected to sensors (17, 22, 23) and to the actuator (16) in a signal-transmitting manner and is intended to control the method according to any of claims 1-13.