METHOD FOR OPERATING A ROUND BALE PRESS AND ROUND BALE PRESS

Description

[0001] The present invention relates to a method for operating a round baler according to the preamble of claim 1. Furthermore, the present invention relates to a round baler according to the preamble of claim 10.

[0002] A method for operating a round baler and a round baler of the type mentioned above are known from DE 197 18 229 A1. In the variable round baler known from DE 197 18 229 A1, the compression pressure for forming a round bale is applied by a pressing element designed as a press belt, which is adjusted by means of two tension arms. The tension arms are in turn connected to actuators designed as hydraulic cylinders for their adjustment, which are supplied with a hydraulic fluid corresponding to the compression pressure to be achieved. For this purpose, a pressure relief valve for regulating the compression pressure is installed in the hydraulic system supplying the hydraulic cylinders. The pressure relief valve sets a limit pressure value that corresponds to the compression pressure to be achieved. If the limit pressure value is exceeded, the pressure relief valve is moved to its open position.

[0003] Furthermore, EP 1 008 292 B1 discloses a round baler and a method for producing highly compacted round bales from agricultural crops, wherein the round baler has only one clamping arm.

[0004] A disadvantage of the round baler described above is that the hydraulic system, which adjusts the compression pressure and belt tension by changing the pressure on the actuators of the two tensioning arms, is a passive device that is sensitive to environmental conditions, particularly uneven crop feed. If the crop feed is uneven, the baling belt gradually loses tension during operation. This is because an uneven crop feed induces vibrations in the baling belt, leading to fluctuating belt tension and hydraulic pressure. Whenever the hydraulic pressure in the system reaches the set limit value that triggers the pressure relief valve, the valve opens, and the hydraulic pressure in the system decreases.This switching behavior, however, leads to a decrease in belt tension over time, and the desired belt tension gradually deviates from the target belt tension. This is unsatisfactory and may result in the formed round bales not exhibiting the desired properties in terms of shape and density.

[0005] The invention is therefore based on the objective of further developing a method for operating a round baler and a round baler in such a way that more efficient operation of the round baler can be achieved.

[0006] From a process engineering perspective, this problem is solved by starting with the preamble of claim 1 in conjunction with its characterizing features. From an apparatus engineering perspective, the problem is solved by the technical features of dependent claim 10. The subsequent dependent claims each represent advantageous embodiments of the invention.

[0007] According to claim 1, a method for operating a round baler is proposed, comprising a press chamber having a variable diameter arranged in a housing and bounded by an endlessly rotating press element, wherein the press element is driven and / or guided by several rollers, wherein at least some of the rollers are adjusted in their position by a first clamping arm and a second clamping arm, each pivotably mounted on the housing side, wherein the first clamping arm and the second clamping arm are adjusted in their position by hydraulically actuated actuators of a hydraulic system, such that at least a compression pressure is generated with which the press element acts to form a round bale.In the invention, an adjustable limit pressure value is specified by a control unit for at least one pressure relief valve to regulate the compression pressure, enabling the valve to be moved from a closed to an open position. The invention provides that the specified limit pressure value is above a pressure value corresponding to the target compression force required to achieve the compression pressure, and that the at least one pressure relief valve is periodically moved to its open position by the control unit. Setting the limit pressure value to a value above the pressure value corresponding to the target compression force required to achieve the compression pressure prevents accidental opening of the at least one pressure relief valve due to pressure fluctuations.which are caused by the vibrations of the pressing element during the forming process in the hydraulic system. The periodic opening of the at least one pressure relief valve during the forming process, particularly independently of pressure fluctuations, ensures that the actual pressing element tension is essentially within the range of a target pressing element tension. The method according to the invention achieves higher sensitivity with which the hydraulic system of the round baler, controlled by the control unit, reacts to uneven crop feed. A further effect is that an operator of the round baler is relieved of the task of monitoring the pressing element tension. The combination of setting the limit pressure value and the periodic opening of the at least one pressure relief valve results in,that the inherently passive hydraulic system is actively used. The period and amplitude of the opening position are controlled as a target value depending on the deviation of the respective actual press-fit tensile stress from the target press-fit tensile stress.

[0008] Preferably, at least one input variable can be specified by an operator using an input / output unit of the control unit in order to adapt the limit pressure value depending on the input variables.

[0009] Input parameters can include crop type, bale shape, bale diameter, and / or absolute or relative values ​​for compaction pressures. The bale diameter input can include minimum and maximum values ​​for the bale's starting and ending diameters. Depending on the bale shape, the input can include absolute or relative values ​​for the compaction pressures, which are assigned to the values ​​for the bale's starting and ending diameters. Possible bale shapes are soft-core bales or hard-core bales. Relative values ​​for compaction pressures are preferred for hard-core bales, while absolute values ​​are preferred for soft-core bales.

[0010] Furthermore, the target compression pressure can be determined based on the input parameters using a recipe-based approach, depending on the current diameter. In this context, "recipe-based" means that the control unit can automatically convert the input parameters for bale-shape-specific production—i.e., a soft-core bale or a hard-core bale—into a compression performance curve dependent on the current diameter, using stored recipes or rule sets. These recipes then change the target compression load depending on the current diameter of the bale being produced.

[0011] In particular, at least the actuation values ​​for the periodic control of the at least one pressure relief valve can be determined using at least one stochastic method. The actuation values ​​can be determined by an estimator via the control unit. Preferably, an estimator from the group of Bayesian filters, such as a particle filter or a Kalman filter, with the estimation algorithms implemented therein, should be used for the invention. The actuation values ​​for the periodic control of the at least one pressure relief valve can be amplitude, pulse duration, and period.

[0012] The control unit can estimate the setpoint values ​​after at least one bale rotation based on the expected density of the round bale and the detected throughput during the forming process. The input parameters can be used to determine the expected density of the round bale at different times during the forming process.

[0013] Preferably, sensor signals representative of the distribution of harvested material picked up by a baler's intake device can be provided by a sensor arrangement on the baler. These sensor signals are evaluated by the control unit to generate control data for the actuators. For this purpose, the sensor arrangement can include a bale shape sensor arrangement configured to monitor the bale shape during the baling process. Such a bale shape sensor arrangement can detect bale shapes that deviate from a substantially circular cylindrical shape, which is attributable to uneven crop feed.

[0014] If an inhomogeneous feed of crop material into the baling chamber is detected, the baling tension can be increased. Increasing the baling tension prevents fluttering of the baling element if the round bale being formed is not perfectly round. This counteracts vibrations in both the baling element and the hydraulic system, thereby preventing or at least minimizing deviations from the target baling tension.

[0015] In particular, the operating pressures of the actuators of each clamping arm can be monitored by a pressure relief valve. In contrast to the prior art solution, which uses a common pressure relief valve to control the compression pressure and monitor the force coupling of the two clamping arms in the hydraulic system, this embodiment uses two pressure relief valves. These valves enable the force balance between the two clamping arms for clamping the pressing element to be controlled by means of a control algorithm.

[0016] Preferably, the specified limit pressure value can be increased depending on the increase in bale diameter. In particular, the limit pressure value can be adjusted to correspond to the profile of the target tensile stress.

[0017] Furthermore, the problem initially set out is solved by a round baler according to the subordinate claim 10.

[0018] According to the dependent claim 10, a round baler is proposed with a baling chamber having a variable diameter arranged in a housing, wherein the baling chamber is bounded by an endlessly rotating baling element, with several rollers which drive and / or guide the baling element, wherein a first clamping arm and a second clamping arm pivotably mounted on the housing side are provided for adjusting the position of at least some of the rollers, wherein hydraulically actuated actuators are provided for adjusting the position of the first clamping arm and the second clamping arm, with which the baling element acts to form a round bale, in order to generate a compression pressure with which the baling element acts to form a round bale.wherein, to regulate the compression pressure, a control unit specifies an adjustable limit pressure value to at least one pressure relief valve for moving the at least one pressure relief valve from a closed position to an open position, wherein the specified limit pressure value is above a pressure value corresponding to a target pressing force required to achieve the compression pressure, and wherein the control unit actuates the at least one pressure relief valve in order to periodically move the at least one pressure relief valve to its open position during the forming process. Reference may be made to all details concerning the proposed method for operating the round baler.

[0019] In particular, the control unit may include an input / output unit which is set up for the input of input variables by an operator.

[0020] The input / output unit can be configured to input crop type, bale shape, bale diameter, and / or absolute or relative values ​​for compaction pressures as input variables. Preferably, the input variables bale diameter and compaction pressures can be set as range values, particularly by means of graphically visualized bar charts.

[0021] Furthermore, the control unit can be configured to adapt the limit pressure value depending on at least one of the input variables.

[0022] According to a preferred further development, the control unit can be configured to determine setting values ​​for the periodic actuation of the at least one pressure relief valve using at least one stochastic method.

[0023] In particular, the round baler can include sensor devices for determining the moisture content of the harvested crop as well as the feed rate received and / or supplied to the baling chamber. The moisture content and feed rate are essential operating and / or environmental parameters that influence the bale formation process. The feed rate can be determined, for example, by detecting the layer height in a feed unit of the baler.

[0024] Preferably, the round baler can have a sensor arrangement configured to provide sensor signals that are representative of the distribution of crop material picked up by a receiving device of the round baler.

[0025] The control unit is designed to receive and evaluate the sensor signals generated by the sensor array and, depending on the evaluated sensor signals, generates control data for controlling the actuators. For this purpose, the sensor array can include a bale shape sensor array, which is configured to monitor the bale shape during the bale-forming process. Such a bale shape sensor array can detect bale shapes that deviate from a substantially circular cylindrical shape, which is attributable to uneven crop feed.

[0026] In particular, a computer program is provided, comprising program instructions that cause a processor to execute and / or control the steps of the method according to any one of claims 1 to 9 when the computer program is running on the processor. The algorithm underlying the computer program for tensioning the pressing device predicts the feed rate of crop and ensures that only the required amount of oil is discharged from the hydraulic system through the at least one pressure relief valve in order to keep the pressing device under control at all times, in particular to prevent fluttering of the pressing device due to insufficient tension.

[0027] The present invention is explained in more detail below with reference to an embodiment illustrated in the drawings.

[0028] They show: Fig. 1 a schematic representation of a round baler with variable baling chamber in side view; Fig. 2 a schematic representation of a control unit of the round baler; Fig. 3 a baling tension-time diagram according to a control system according to the prior art; and Fig. 4 a baling tension-time diagram according to the method according to the invention.

[0029] Fig. 1Figure 10 shows a schematic side view of a round baler with a variable baling chamber. The round baler 10 has a variable baling chamber 12 in a housing 14. For pressing a round bale 16, the baler 10 has a continuously rotating pressing element 16. The pressing element 16 can be formed from one or more press belts 18 or chains. The pressing element 16 is guided by a plurality of rollers 20, which can be stationary or variably arranged. A roller 20a, designed as a stationary drive roller, transmits a drive force to the pressing element 16. A receiving device 22 picks up crop material, usually in the form of a swath, guides it along a rotor 24, where the crop is chopped, and introduces it into the baling chamber 12, where the crop is compacted and pressed into a round bale (not shown).The rotor 24 can extend into the pressing chamber 12 and be in contact with a round bale, for example, rotating clockwise, and rotate with it. A finished round bale is usually wrapped with a wrapping material, such as twine or netting, before being ejected from the pressing chamber 12 to stabilize the bale.

[0030] The pressing chamber 12, in which the harvested crop is compacted, is formed by an effective length of the pressing element 16. An effective length of the pressing element 16 is the length of the pressing element 16 that encloses the pressing chamber 12 and, in particular, acts in contact with a round bale and transmits a pressing force to it.

[0031] The size of the compression chamber 12 can be varied by repositioning rollers 20. The repositionable rollers 20 are arranged at the ends of a first clamping arm 26 and a second clamping arm 28. The first clamping arm 26 is pivotally mounted on the housing side and has two rollers 20 at its free end, which guide a loop of the pressing element 16. The size of the compression chamber 12 can be changed by altering the position of the first clamping arm 26. As the crop is fed further into the compression chamber 12, the round bale grows continuously, and the first clamping arm 28 is deflected with increasing size of the compression chamber 12 and, in particular, with increasing diameter of the round bale 16. With increasing deflection of the first clamping arm 26, the size of the compression chamber 12 and the effective length of the pressing element 16 increase.To avoid an excessive increase in the compaction pressure, additional pressing medium 16 is provided by relocating the second clamping arm 28, which clamps a loop of the pressing medium 16.

[0032] For this purpose, the second clamping arm 28 is pivoted such that the loop of the clamping element 16 is reduced, and the resulting available length of the clamping element 16 can be used as the effective length. Two hydraulically actuated actuators 30 are assigned to the first clamping arm 26, and a further hydraulically actuated actuator 32 is assigned to the second clamping arm 28.

[0033] The round bale in the baling chamber 12 grows in size as the amount of crop fed increases, causing the first clamping arm 26 to deflect and the effective length of the pressing element 16 to increase. The deflection of the first clamping arm 26 is controlled by at least one pressure relief valve 34, which, in addition to influencing the bale shape (soft core or hard core), also affects the compression pressure. The pressing element 16 also exerts a force on the free end of the second clamping arm 28, which, due to the illustrated arrangement of the rollers 20, can cause the second clamping arm 28 to pivot away from the first clamping arm 26. Since the loop of the pressing element 16 formed there decreases when the second clamping arm 28 pivots, the length of the pressing element 16 available for effective compression increases. The compression force can also be influenced by pivoting the second clamping arm 28.The deflection of the second clamping arm 28 is controlled here and preferably by a further pressure relief valve 36.

[0034] In Fig. 2Figure 1 shows an exemplary representation of part of a hydraulic system 40 of the round baler 10. The compression pressure for forming the round bale 16 is applied by the pressing device 16, which is adjusted by means of the first and second clamping arms 26, 28. For their adjustment, the clamping arms 26, 28 are connected to the actuators 30, 32, which are designed as hydraulic cylinders and are pressurized with a hydraulic fluid according to the compression pressure to be achieved. The required pressure values ​​can be set by means of the pressure relief valves 34, 36, according to the compression pressure to be achieved. The operating pressures of the actuators 30, 32 of each clamping arm 26, 28 are monitored by the respective pressure relief valve 34, 36. The two pressure relief valves 34, 36 make it possible to control or regulate the force balance between the clamping arms 26, 28 by means of a control algorithm.For this purpose, the baler 10 has a control unit 38 which is configured to set the limit pressure values ​​required for the desired compression pressure at the pressure relief valves 34, 36 and to execute the control algorithm. In principle, the hydraulic system 40 can also comprise only one pressure relief valve 34.

[0035] Fig. 2 Figure 38 also shows, in an exemplary and schematic manner, the control unit 38, which comprises a storage unit 42, a processing unit 44, and an input / output unit 46. Using the input / output unit 46, an operator of the baler 10 can input at least one parameter that will form the basis for bale production. Input parameters can include crop type, bale shape, bale diameter, and / or values ​​for compaction pressures. Compaction pressure values ​​can be entered as absolute or relative values.

[0036] In Fig. 3 An exemplary tensile stress-time diagram for a press brake system based on a state-of-the-art control system is shown. Fig. 3 Only excerpts of a target bale tension curve 48, a bale tension curve 50 without intervention by a control system, and a bale tension curve 52 controlled according to the state of the art are shown. The target bale tension curve 48, as shown, corresponds to the desired target compaction pressure during the round bale forming process.

[0037] The course of the in Fig. 3The unregulated baling tension 50 shown as an example occurs when the vibrations of the baling element 16 introduced into the hydraulic system 40 due to uneven crop feed are not counteracted by a control system; that is, the unregulated baling tension 50 of the baling element 16 is not temporarily reduced. With an uneven crop feed, a vibration is induced in the baling element 16, leading to an increasing baling tension 50 and, correspondingly, to an increasing hydraulic pressure in the hydraulic system 40. Accordingly, the curve of the unregulated baling tension 50 exhibits amplitudes that lie below and above the curve for the target baling tension 48.

[0038] The profile of the press-fit tension 52, controlled according to the state of the art, is based on a set limit pressure value plimit, which leads to the switching of at least one pressure relief valve 34, 36, or here both pressure relief valves 34, 36. The set limit pressure value plimit is based on the profile of the target press-fit tension 48, whereby the maximum value for the operating pressure of the actuators 30, 32 to achieve the target press-fit tension 48 corresponds to the limit pressure value plimit. If the actual press-fit tension exceeds the specified value according to the... Fig. 3As the depicted profile of the pressable tensile stress 50 approaches the target pressable tensile stress 48, the state-of-the-art control system detects when the limit pressure value plimit is exceeded, leading to the temporary opening of the pressure relief valve(s) 34, 36. Thus, whenever the hydraulic pressure in the hydraulic system 40 corresponds to the set limit pressure value plimit, which triggers the switching of a pressure relief valve 34, 36, the pressure relief valve 34, 36 is opened, and the hydraulic pressure in the hydraulic system 40 decreases. This results in a smoothing of the tensile stress peaks in the profile of the unregulated pressable tensile stress 50, while the profile of the controlled pressable tensile stress 52 decreases with increasing bale diameter during the forming process, relative to the profile of the target pressable tensile stress 48.

[0039] In Fig. 4An exemplary tensile stress-time diagram according to the inventive method is shown. This diagram again depicts the curve of the target tensile stress 48 and the curve of the unregulated tensile stress 50, which occurs without any control or regulation.

[0040] Furthermore, the diagram shows a curve 54 for a limit pressure value plimit, which is set depending on the input variables. The limit pressure value curve 54 depends in particular on the compression pressure to be applied and the bale diameter. The specified limit pressure value plimit lies above a pressure value that corresponds to the pressing force tensile stress required to achieve the compression pressure, according to the curve of the target pressing force tensile stress 48. This prevents the pressure relief valves 34, 36 from accidentally opening. At the same time, at least one pressure relief valve 34, 36 is periodically moved to its open position during the forming process. A signal curve 56 for pulse duration modulation to control the at least one pressure relief valve 34, 36, in order to periodically move it to its open position during the forming process, is also shown. Fig. 4As illustrated by example, the pulse-duration-modulated control of the pressure relief valves 34, 36 by the control unit 38 ensures that the actual press-fit tensile stress curve lies essentially within the range of the target press-fit tensile stress curve 48. The higher limit pressure value plimit allows pressure peaks in the hydraulic system 40, which, according to the prior art, are immediately smoothed out by opening at least one pressure relief valve 34, 36. The targeted control of the pressure relief valves 34, 36 during the forming process has the effect that the actual press-fit tensile stress curve lies essentially within the range of the target press-fit tensile stress curve 48.For this purpose, amplitude, pulse duration t1, t2, and period T1, T2 are determined and set as adjustment values ​​depending on the target press pressure 48 or the deviation of the actual press pressure from the target press pressure 48. The limit pressure value curve 54 can be based on the target press pressure 48.

[0041] The control values ​​amplitude, pulse duration t1, t2, and period T1, T2 for the periodic control of the at least one pressure relief valve 34, 36 are determined using at least one stochastic method. For this purpose, the control unit 38 estimates the control values ​​that will be established after at least one bale rotation from the expected density of the round bale and a detected throughput during the forming process. The round baler 10 can include sensor devices for determining the moisture content of the ingested crop as well as the feed quantity received and / or supplied to the baling chamber. The moisture content and the feed quantity represent essential operating parameters and / or environmental parameters that influence the bale forming process. The feed quantity of ingested crop can be determined, for example, by layer height detection in a receiving unit of the baler 10.

[0042] Furthermore, sensor signals are provided on the baler 10 by a sensor arrangement 58, which may be multi-part. These signals are representative of the transverse distribution of the crop material picked up by the baler 10's intake device 22. The sensor signals from the sensor arrangement 58 are evaluated by the control unit 38 to generate control data for actuating the actuators 30 and 32. Upon detection of an inhomogeneous feed of crop material into the press chamber 12, the actual tension of the baling element is increased as a reaction.

[0043] The control unit 38 determines the setpoints for the pulse-duration-modulated control of the pressure relief valves 34, 36, preferably by means of an estimator 60. Preferably, for the invention, an estimator 60 from the group of Bayesian filters, such as a particle filter or a Kalman filter, with the estimation algorithms implemented therein, should be used. Reference symbol list

[0044] 10 Round baler 12 Press chamber 14 Housing 16 Pressing device 18 Press belt 20 Roller 20a Roller 22 Mounting device 24 Rotor 26 First tension arm 28 Second tension arm 30 Actuator 32 Actuator 34 Pressure relief valve 36 Pressure relief valve 38 Control unit 40 Hydraulic system 42 Storage unit 44 Calculation unit 46 Input / output unit 48 Target press tension 50 Press tension 52 Press tension 54 Limit pressure value trend 56 Signal trend 58 Sensor arrangement 60 Estimator t1 Pulse duration / Setpoint t2 Pulse duration / Setpoint T1 Period / Setpoint T2 Period / Setpoint

Claims

1. Method for operating a round baler (10) with a pressing chamber (12) which is disposed in a housing (14), has a variable diameter and is delimited by a continuously revolving pressing means (16), wherein the pressing means (16) is driven and / or guided by a plurality of rollers (20, 20a), wherein at least some of the rollers (20, 20a) are adjusted in terms of their position by a first tensioning arm (26) and a second tensioning arm (28) which are in each case pivotably mounted on the housing, wherein the first tensioning arm (26) and the second tensioning arm (28) are adjusted in terms of their position by hydraulically activated actuators (30, 32) of a hydraulic system (40) in such a way that at least one compression pressure by way of which the pressing means (16) acts to form a round bale (16) is generated, wherein for feedback-controlling the compression pressure, an adaptable limit pressure value (pGrenz) for transferring the at least one pressure control valve (34, 36) from a closed position to an open position is specified to at least one pressure control valve (34, 36) by a control unit (38), characterized in that the specified limit pressure value (pGrenz) is above a pressure value corresponding to a setpoint pressing means tension (48) required for achieving the compression pressure, and in that the at least one pressure control valve (34, 36) is periodically transferred to its open position by actuation by the control unit (38).

2. Method according to Claim 1, characterized in that by means of an input-output unit (46) of the control unit (38) at least one input variable is specified by an operator in order to adapt the limit pressure value (pGrenz) as a function of the input variables.

3. Method according to Claim 2, characterized in that a crop material type, a bale shape, bale diameter and / or absolute or relative values for compression pressures are specified as input variables.

4. Method according to one of the preceding claims, characterized in that actuating values (t1, t2; T1, T2) for the periodic actuation of the at least one pressure control valve (34, 36) are determined using at least one stochastic method.

5. Method according to Claim 4, characterized in that the actuating values (t1, t2; T1, T2) established after at least one bale rotation are estimated by the control unit (38) from an expected density of the round bale (16) and a detected throughput during the forming procedure.

6. Method according to one of the preceding claims, characterized in that provided by a sensor assembly (58) on the baler (10) are sensor signals which are representative for a distribution of crop material received by a pick-up device (22) of the baler (10), and in that the sensor signals are evaluated by the control unit (38) to generate control data for actuating the actuators (30, 32).

7. Method according to Claim 5, characterized in that, when an inhomogeneous feed of crop material into the pressing chamber (12) is detected, the pressing means tension is increased.

8. Method according to one of the preceding claims, characterized in that working pressures of the actuators (30, 32) of each tensioning arm (26, 28) are in each case monitored by one of the pressure control valves (34, 36).

9. Method according to one of the preceding claims, characterized in that the specified limit pressure value (pGrenz) is increased as a function of the increase in the bale diameter.

10. Round baler (10) with a pressing chamber (12) which is disposed in a housing (14), has a variable diameter and is delimited by a continuously revolving pressing means (16), with a plurality of rollers (20, 20a) which drive and / or guide the pressing means (16), wherein provided for adjusting at least some of the rollers (20, 20a) in terms of their position are a first tensioning arm (26) and a second tensioning arm (28) which are pivotably mounted on the housing, wherein provided for generating a compression pressure by which the pressing means (16) acts for forming a round bale (16) are hydraulically activated actuators (30, 32) for adjusting the position of the first tensioning arm (26) and of the second tensioning arm (28) by which the pressing means (16) acts for forming a round bale (16), wherein for feedback-controlling the compression pressure, a control unit (38) specifies an adaptable limit pressure value (pGrenz) for transferring the at least one pressure control valve (34, 36) from a closed position to an open position to at least one pressure control valve (34, 36), characterized in that the specified limit pressure value (pGrenz) is above a pressure value corresponding to a setpoint pressing means tension (48) required for achieving the compression pressure, and in that the control unit (38) actuates the at least one pressure control valve (34, 36) to periodically transfer the at least one pressure control valve (34), 36) to its open position during the forming procedure.

11. Round baler (10) according to Claim 10, characterized in that the control unit (38) comprises an input-output unit (46) which is configured for the input of least one input variable by an operator.

12. Round baler (10) according to Claim 11, characterized in that the input-output unit (46) is configured for the input of crop material type, bale shape, bale diameter and / or absolute or relative values for compression pressures as an input variable.

13. Round baler (10) according to Claim 11 or 12, characterized in that the control unit (38) is configured to adapt the limit pressure value (pGrenz) as a function of at least one of the input variables.

14. Round baler (10) according to one of Claims 10 to 13, characterized in that the control unit (38) is configured to determine actuating values (t1, t2; T1, T2) for the periodic actuation of the at least one pressure control valve (34, 36) using at least one stochastic method.

15. Round baler (10) according to one of Claims 10 to 14, characterized in that disposed on the baler (10) is a sensor assembly (58) which provides sensor signals which are representative for a distribution of crop material received by a pick-up device (22) of the baler (10), and in that the control unit (38) is configured to evaluate the sensor signals to generate control data for actuating the actuators (30, 32).