METHOD AND DEVICE FOR CALIBRATING A COUPLING AND AGRICULTURAL TRACTOR

Description

[0001] The invention relates to a method according to the preamble of independent claim 1, a device according to the preamble of independent claim 12 and an agricultural tractor according to the preamble of independent claim 14.

[0002] From EP 1 293 697 A2, a method and a device for controlling a hydraulically operated clutch, in particular a power take-off (PTO) clutch, within the drive train of an agricultural machine are known. The clutch is controlled by an electromagnetically actuated proportional valve. Sensors determine the rotational speed before and after the clutch, from which the clutch slip is calculated. By controlled, time-dependent changes in the value of a valve flow of the proportional valve corresponding to the clutch pressure, the clutch slip is continuously adjusted to and maintained at a constant value. It is assumed that, at a constant or regulated slip value, there is a fixed relationship between the output torque acting on the PTO shaft and the valve flow, which can be determined through experiments or theoretical calculations.Using this fixed relationship, the output torque is determined from the given slip value and the valve flow. A prerequisite for determining the torque is therefore the provision of the aforementioned fixed relationship in the form of calibration data for a clutch. US 2015 / 094922 A1 and DE 10 2018 200 835 A1 disclose and teach calibration methods in a broader sense. US 10,060,486 B2 and US 2018 / 187728 A1 deal with the engagement of a power take-off clutch. US 2017 / 198,656 A1 discloses a method for maintaining engine speed.

[0003] Based on this state of the art, the object of the present invention is to propose a method, a device and an agricultural tractor which enable precise calibration within a drive train of the tractor in a technically simple manner.

[0004] This problem is solved by a method with the features of claim 1, a device with the features of claim 12, and an agricultural tractor with the features of claim 14. The dependent claims relate to particularly advantageous embodiments of the invention. According to the invention, a method for calibrating a selected clutch arranged within the drive train of an agricultural vehicle is proposed. The agricultural vehicle is preferably a tractor. The selected clutch can be controlled between a closed state (with complete power transmission) and an open state (with interrupted power transmission). During calibration, the selected clutch is connected on the drive side to a running drive motor of the tractor. On the output side, the clutch is connected to an output shaft.The clutch is actuated, and the value of a physical quantity that triggers the clutch actuation (e.g., the electrical current of a hydraulic valve acting on the clutch) is determined or set. Simultaneously, and in particular at the same time, a physical quantity representing the rotation of the output shaft, namely the angular acceleration according to the invention, is determined. Depending on this rotational quantity of the output shaft—and especially taking into account other physical quantities such as a known moment of inertia of this output shaft—a torque of the selected clutch can be determined. The rotational quantity of the output shaft is therefore assigned to the value of the physical quantity that triggers the clutch actuation. Depending on this assignment, clutch-specific calibration data (e.g., a table of values, formula(s), characteristic curve) can be generated.

[0005] The calibration data for the selected coupling can be generated with minimal technical effort and can therefore be provided cost-effectively for various technical applications. The basic technical effort required to generate, in particular to determine and / or calculate, the calibration data remains low while maintaining high data accuracy. This is achieved by simply defining or setting the value of a physical quantity that triggers the coupling control (e.g., the electrical control current of a hydraulic valve controlling the coupling) and, in this defined or set state, determining a physical quantity representing the rotation of the output shaft (e.g., angular acceleration). The relationship between the value of the coupling control quantity and the rotational quantity of the output shaft can be established using other known values ​​of characteristic physical quantities (e.g.,(a moment of inertia of the output shaft) are mathematically combined to generate derived calibration data for this coupling.

[0006] In particular, the calibration data, due to the corresponding specific physical quantities and values, contain a torque characteristic of the selected coupling. In a preferred technical application, the calibration data can therefore be used to determine the torques acting at specific positions in the drivetrain of an agricultural tractor. This allows for the application of the calibration data to support a technically simple and cost-effective drive management system (e.g., traction control) for the tractor.

[0007] The method can be applied to any coupling within the drivetrain of the towing vehicle. This allows for even more flexible technical applications of the generated calibration data. For example, it can support the precise determination of torques within the drivetrain of an agricultural tractor using multiple and / or different couplings.

[0008] In an advantageous embodiment, the procedure is carried out successively for differently defined or set values ​​of the physical quantity that controls the clutch. In this way, a complete and precise clutch-specific characteristic curve can be generated as calibration data.

[0009] As already mentioned, a physical quantity representing the rotation of the output shaft is determined during the process. This quantity is the rotational speed of the output shaft and, according to the invention, either the angular velocity of the output shaft or the angular acceleration of the output shaft. The values ​​of these quantities can advantageously be determined without additional technical effort using a speed sensor already present in the drive train.

[0010] According to the invention, the temporal profile of the angular acceleration, as the determined rotational quantity of the output shaft, is structured such that it exhibits an acceleration phase caused by the actuation of the selected clutch. Furthermore, the temporal profile of this angular acceleration includes a deceleration phase (negative acceleration), which is caused, at least along a certain time segment, by the actuation of a subsequent clutch unit in the power flow of the drivetrain. With such temporally determined acceleration and deceleration profiles of the angular acceleration, physical properties of the drivetrain, in particular drag torques of the clutches and / or frictional torques and / or bearing frictions of the drive shaft, can be taken into account when generating the calibration data. This enhances the physical accuracy of the calibration data.

[0011] In a further embodiment of the invention, the moment of inertia of the output shaft is taken into account by integrating this moment of inertia, or its value, into the clutch-specific calibration data. In particular, the moment of inertia of the output shaft is already known or can be determined as known through calculations. Including the moment of inertia in the calibration data facilitates its technical application for torque determination, since a torque can preferably be derived from a mathematical product of a moment of inertia and a rotational quantity, which, according to the invention, is the angular acceleration.

[0012] In a particularly advantageous embodiment, the calibration data includes the value of at least one physical correction parameter. In other words, the calibration data to be generated is supplemented by one or more correction parameters or their correction values. Including the correction parameter(s) supports the generation of technically precise calibration data for the selected coupling. Specifically, the at least one physical correction parameter comprises the drag torque of the selected coupling and / or the friction torque and / or the bearing friction of a coupling unit downstream of the output shafts in the power flow of the drive train.

[0013] Preferably, the selected coupling and one or more coupling units downstream of the output shaft in the power flow are controlled in a specific manner and sequentially for specific durations during the execution of the process in order to realize suitable acceleration and deceleration sequences on the output shaft and to record the values ​​of relevant physical quantities arising during these sequences, e.g., the rotational speeds, and, according to the invention, the values ​​of an angular acceleration of the output shaft. This allows the aforementioned at least one physical correction quantity, or its values, to be determined efficiently using process engineering and taken into account in the calibration data. In particular, at least one of the following process steps is carried out during the acceleration and deceleration sequences: The output shaft is disconnected from all upstream and downstream drive connections in the power flow of the drivetrain; the output shaft is accelerated by being connected to the drive motor and disconnected from the downstream drive connections in the power flow of the drivetrain; the output shaft connected to the drive motor rotates at a speed, in particular a constant speed; the rotating output shaft is decelerated by actuating a clutch unit downstream in the power flow of the drivetrain with a defined value of a physical quantity that effects its clutch actuation, wherein the output-side torque of this clutch unit is zero.

[0014] An advantageous further development provides that the selected clutch is in its open state during deceleration of the rotating output shaft. This ensures that specific physical deceleration characteristics, particularly of the output shaft, are taken into account with high accuracy in the calibration data.

[0015] In a further preferred embodiment, a parking lock and / or a braking device of the towing vehicle is activated at least during the process step of decelerating the output shaft. This enables, in a technically simple manner, a blocking of certain sections of the drivetrain during calibration, thus creating process states with zero torque. For example, this process state can be used with a rotating output shaft whose rotation is to be decelerated by a subsequent clutch unit in the power flow, by actuating the latter (e.g., via a hydraulic valve) and simultaneously ensuring that the output torque is zero.

[0016] In an embodiment of the invention, the engine speed of the towing vehicle's drive motor is kept constant, at least temporarily, and in particular throughout the entire process, during the execution of the method for generating clutch-specific calibration data for a selected clutch. This ensures consistent physical conditions during the process and facilitates the generation of technically accurate calibration data.

[0017] The invention further relates to a device for calibrating a selected clutch, which is arranged within the drivetrain of an agricultural tractor and can be controlled between a closed and an open state. The device comprises a control unit for carrying out the method according to any one of claims 1 to 11. In particular, the control unit controls the selected clutch between a closed and an open state. Different clutch states are achieved, in particular, by the control unit changing or varying the value of a physical quantity that effects the clutch control. The selected clutch is connected on the drive side to a running drive motor of the tractor and on the output side to an output shaft.During the process, the control unit sets or adjusts the value of a physical quantity that triggers the clutch actuation, e.g., the electrical control current of a hydraulic valve that actuates the clutch. Simultaneously, and especially at the same time, the control unit determines a physical quantity representing the rotation of the output shaft (e.g., angular velocity). The control unit then assigns the set or adjusted value of the actuation quantity to the rotation quantity and their respective values. This assignment can be performed, for example, for different set or adjusted values ​​of the actuation quantity, similar to a table of values. Based on this assignment and, if applicable, the values ​​of other characteristic physical quantities (e.g., the moment of inertia of the output shaft), the control unit can generate calibration data (e.g., a table of values, formula(s), characteristic curve) for the selected clutch.In particular, the calibration data, due to the corresponding specific physical quantities, contains a torque characteristic of the selected coupling. Therefore, during operation of the towing vehicle, various torques acting in the drivetrain can be determined with minimal technical effort using the calibration data. With the torques determined in this way, the device can support a technically simple and cost-effective drive management system (e.g., traction control) for the towing vehicle.

[0018] The device and its control unit can generate coupling-specific calibration data, particularly for any coupling within the drivetrain of the agricultural tractor. This allows for more flexible technical applications of the generated calibration data, such as determining torques within the drivetrain using multiple and / or different couplings.

[0019] The control unit can be configured as an electronic module, an embedded system, a computing unit, a computer, or as a module for controlling and / or regulating individual components of the device. The control unit can include a processor, memory, and / or all software, hardware, algorithms, connections, and in particular sensors, necessary for controlling and / or regulating the device or its components. Individual or all process steps of the disclosed method can be configured as a program or algorithm that can be executed on and / or with the control unit. The control unit can include any device capable of analyzing data from various sensors, comparing data, and making the necessary decisions to control and / or regulate the operation of the device and to execute the necessary tasks for controlling the operation of the device.

[0020] The control unit can be connected to the device, in particular to its components (e.g., sensors, hydraulic valves), preferably via a signal connection and / or signal transmission and / or data transmission. The control unit can serve to control and / or regulate and / or actuate the interconnected components. A signal connection and / or signal transmission and / or data transmission means that an exchange of signals takes place between the connected components. The connection can be wired, in particular with a cable, and / or wireless, i.e., via radio, for example, Bluetooth. The communication bus can be, for example, ISOBUS, CAN bus, or similar. The control unit can be assigned to the device for carrying out the process and / or to the agricultural tractor, in particular, it can be located on the tractor.The control unit can also be designed in two parts, for example, as part of the agricultural tractor and as part of the device. The control unit can be directly connected to the input / output unit located in the cab of the tractor, through which data entered by an operator or the driver can be transmitted to the control unit, or received and output by the control unit. However, it is also conceivable that the control unit is indirectly connected to the input / output unit via a higher-level control unit.

[0021] In one embodiment of the invention, the device comprises a hydraulic valve for controlling a selected clutch of the drive train. The hydraulic valve can be actuated and / or adjusted by means of the control unit, so that the clutch can be controlled between a closed and an open state. In particular, the control unit sets or adjusts the values ​​of an electrical control current for the hydraulic valve. Furthermore, the control unit can monitor and / or process the set or adjusted values. The control unit can also process the output pressure of this hydraulic valve (e.g., by means of a pressure sensor).

[0022] According to the invention, the device comprises a speed sensor for detecting the rotational speed of an output shaft, which is connected to the drive side of the selected coupling. Using the detected rotational speed values, in addition to the rotational speed itself, other physical quantities representing the rotation of the output shaft, namely, according to the invention, the angular acceleration, can be determined in a technically simple manner.

[0023] The invention further relates to an agricultural towing vehicle, preferably a tractor, with a device according to claim 12 or 13. The device integrated into the towing vehicle allows any couplings within the drive train of the towing vehicle to be calibrated with minimal technical effort.

[0024] This is achieved by having a control unit of the device for the selected coupling and an output shaft connected to this coupling on the drive side assign the values ​​of specific physical quantities to each other. The determined value of a rotational quantity (e.g., angular velocity) of the output shaft is assigned to the defined or set value of a control quantity (e.g., electrical control current of a hydraulic valve). Based on this assignment and, if applicable, the values ​​of other characteristic physical quantities (e.g., the moment of inertia of the output shaft), the device of the towing vehicle can generate calibration data (e.g., a table of values, formula(s), characteristic curve) for the selected coupling. In particular, due to the assigned specific physical quantities, the calibration data contains a torque characteristic of the selected coupling.During operation of the towing vehicle, various torques acting in the drivetrain can therefore be determined with minimal technical effort using the coupling-specific calibration data. The torques determined in this way can support a technically simple and cost-effective drive management system (e.g., traction control) for the towing vehicle.

[0025] In particular, the agricultural tractor can generate coupling-specific calibration data for any coupling within its drivetrain using the device. This allows for even more flexible technical applications of the generated calibration data, such as determining torques within the drivetrain using multiple and / or different couplings.

[0026] The following parameters are particularly relevant for generating calibration data β for the method, the device and the towing vehicle for a selected coupling Km.n: the fixed or set control currents I_st_m.n (at the coupling Km.n) and I_st_m+1.n (at the coupling Km+1.n), the rotational speeds n_m of the output shaft Wm detected by means of the speed sensor and the angular acceleration α of the output shaft Wm determined from this, the moment of inertia Jm of the output shaft Wm known by calculation, the set rotational speed n_motor of the drive motor, the gear ratio Rm.n.

[0027] These quantities or their values ​​are assigned to each other to generate the calibration data β depending on this assignment.

[0028] For the calibration data β = (β1, β2, β3, β4) the following equation applies by definition: β = X \ α where X can be defined as a matrix with four vectors X1, X2, X3, X4. The following equations apply. X 1 = n_m 2 X 2 = n_m − n_motor ⋅ Rm . n 2 X 3 = l_st_m . n X 4 = l_st_m + 1 . n

[0029] Starting with equations GI. 2 to GI. 5, equation GI. 1 is calculated. This yields the result vector β. The following applies: β 1 = f 1 / Jm β 2 = f 2 / Jm β 3 = Mm / Jm β 4 = Mm + 1 / Jm

[0030] The components β1 and β2 can be considered as physical correction quantities.

[0031] The component β1 contains a factor f1, which includes the sum of the drag torque M_sm+1 to the couplings Km+1.1 to Km+1.n and the friction torque M_r, i.e. f1 = -(M_sm+1-M_r).

[0032] The component β2 contains a factor f2 = - M_sm, which includes the drag torque M_sm to the couplings Km.1 to Km.n.

[0033] The torque Mm is calculated as β3 · Jm for the clutch Km.n at a control current I_st_m.n set by the control unit 52. The torque Mm+1 is calculated as β4 · Jm for the clutch Km+1.n at a control current I_st_m+1.n set by the control unit 52.

[0034] The aforementioned procedure steps for calibrating a selected coupling Km.n can be repeated for differently defined values ​​of the control currents I_st_m.n and I_st_m+1.n, such that the calibration data β, in particular component β3, contains a torque Mm of the coupling Km.n for different control currents I_st_m.n. In other words, the calibration data β, in particular component β3, represents a torque characteristic of the coupling Km.n. This torque characteristic can be provided as a complete characteristic curve using the calibration data β, in particular component β3.

[0035] The calibration data β can be generated for any couplings Km.n within the drive train or transmission arrangement.

[0036] The invention, as well as further advantages and advantageous developments and embodiments of the invention, both in terms of apparatus and process engineering, are explained in more detail below with reference to exemplary embodiments and the drawings. Components that are functionally identical or comparable are marked with the same reference numerals. The drawings show: Fig. 1 a schematic representation of an agricultural tractor according to the invention, and Fig. 2 a schematic and block diagram-like representation of individual components of the agricultural tractor and a first embodiment of the device according to the invention for carrying out the method according to the invention, and Fig. 3 a flowchart with process steps for carrying out the method according to the invention.

[0037] Figure 1Figure 1 shows a schematic representation of an agricultural towing vehicle 10 according to the invention, in particular in the form of a tractor, with a drive train 20 in one possible embodiment. The basic structure of an agricultural towing vehicle 10 is assumed to be known to those skilled in the art. The towing vehicle 10 further comprises a cab 12, a front axle 14, and a rear axle 26. The front axle 14 and the rear axle 26 are part of the drive train 20, wherein the rear axle 26 is generally permanently driven and the front axle 14 is generally engaged as needed.

[0038] The drive train 20 further comprises a drive motor 22, which can be an internal combustion engine, and a transmission structure, which can be composed of various individual transmission components. Starting from the drive motor 22, the transmission structure can include a transmission assembly 30, a drive unit 24, a rear axle transmission 32, and a front axle transmission 34 in the power and torque flow. The transmission assembly 30 allows drive power from the drive motor 22, particularly with different gear ratios, to be transmitted to the rear axle 26 and, if required, additionally to the front axle 14. The rear axle 26, which converts the rotation of the front and / or rear axle (via associated ground engagement devices) into forward motion of the tractor 10, is therefore driven at a different speed depending on the gear ratio selected in the transmission assembly 30.The towing vehicle 10 can have one or more ground engagement means in the form of wheels 28, which engage with a surface to transmit driving forces and / or by means of which the towing vehicle 10 is supported on the surface. The towing vehicle 10 can also have a chassis, wherein the chassis can in particular be supported by the wheels suspended on the front and rear vehicle axles 14, 26.

[0039] The towing vehicle 10 also contains a device 50 according to the invention with a control unit 52 for carrying out the method according to the invention.

[0040] Figure 2 Figure 50 shows a schematic and block diagram-like representation of an embodiment of the device 50 and individual components of the towing vehicle 10. The transmission arrangement 30 has a number of 1 to m transmission stages G, where in the present example m = 3, consequently there are three transmission stages G1, G2, G3.

[0041] The drive motor 22 is drive-connected to the first gear stage G1 on the output side. The first gear stage G1 includes, for example, three couplings K1.1, K1.2, K1.3, each of which is drive-connected to an output shaft W1 by means of a specific gear ratio R1.1, R1.2, R1.3. The gear ratios R1.1, R1.2, R1.3 are preferably designed as gear sets or gear stages. The couplings K1.1, K1.2, K1.3 are drive-connected to the drive motor 22 on the input side. On the output side, the couplings K1.1, K1.2, K1.3 are drive-connected to the output shaft W1. Clutches K1.1, K1.2, and K1.3 can each be controlled via a hydraulic valve between a closed state (with full power transmission) and an open state (with interrupted power transmission). This control is illustrated using hydraulic valve 54 for clutch K1.1 as an example.The control unit 52 can actuate and / or adjust the valve 54. The control unit 52 sets, adjusts, and / or processes the values ​​of an electrical control current I_st_1.1 for the hydraulic valve 54. The coupling K1.1 can then be actuated by means of the control current I_st_1.1 or by means of a hydraulic output pressure p_hy1 of the valve 54.

[0042] A physical quantity representing the rotation of the output shaft W1, e.g., its rotational speed n1, is detected or determined by means of a speed sensor 56. From this, for example, an angular acceleration α of the output shaft W1 can be derived. The speed sensor 56, as well as the hydraulic valve 54 and other valves for controlling the other clutches K1.2, K1.3 in the transmission stage G1, are preferably part of the device 50.

[0043] The previously described design of gear stage G1 can also apply analogously to gear stage G2 and further gear stages Gm. For example, in gear stage G2, the clutches K2.1, K2.2, and K2.3 can each be controlled by a hydraulic valve 58. A physical quantity that triggers the clutch control is a control current I_st_2.1, set by the control unit 52, or a hydraulic output pressure p_hy2 of the valve 58. The clutch units, in the form of clutches K2.1, K2.2, and K3.3, are arranged downstream of the output shaft W1 in the power flow of the drive train 20. On the input side, clutches K2.1, K2.2, and K3.3 are connected to the output shaft W1, and on the output side, they are each connected to an output shaft W2 via a specific gear ratio R2.1, R2.2, and R2.3, respectively. The translations R2.1, R2.2, R2.3 are in turn preferably designed as gear sets or gear stages.A physical quantity representing the rotation of the output shaft W2, e.g., its rotational speed n2, is determined by means of a speed sensor 60. The speed sensor 60, as well as the hydraulic valve 58 and other valves for controlling the other clutches K2.2, K2.3 in the transmission stage G2, are preferably components of the device 50.

[0044] Preferably, the same applies to the construction of the transmission stage Gm with the clutch units in the form of clutches K3.1, K3.2, K3.3 and the gear ratios R3.1, R3.2, R3.3 to an output shaft Wm. The output shaft Wm is connected in the power flow of the drive train 20 to the rear vehicle axle 26 and, if required – in the case of a closed all-wheel drive clutch 62 – also to the front vehicle axle 14. By means of an activatable parking lock 64 and / or a braking device 66 of the towing vehicle 10, the output shaft Wm and upstream components in the power flow in the transmission arrangement 30 or in the two transmission stages G1, G2 can be locked. This allows, for example, the output torque of clutch K2.1 to be zero.

[0045] As already mentioned, the number of clutches K shown in the gear arrangement 30 is merely an example. Individual gear stages G may contain a different number than three clutches K, and the number of clutches K in the individual gear stages G may differ from one another.

[0046] Figure 3 Figure 1 shows a flowchart with individual steps of the procedure for calibrating a selected coupling K within the drive train 20 or within the transmission arrangement 30. Coupling K1.1 is selected as an example, and the procedure steps for its calibration are explained below.

[0047] In process step S1, the output shaft W1 downstream of the selected clutch K1.1 is disconnected from all upstream and downstream drive connections by placing the selected clutch K1.1 (and, if applicable, clutches K1.2 and K1.3) and clutch K2.1 (and, if applicable, clutches K2.2 and K2.3) in their open state (I_st_1.1 = 0, I_st_2.1 = 0). In process step S2, the drive motor 22 runs at a constant speed n_m. In process step S3, the parking lock 64 and / or the brake device 66 is activated, and all clutches Km.1, Km.2, and Km.3 downstream of the output shaft W2 are in their closed state. This blocks the output shaft W2.

[0048] In a further process step S4, the output shaft W1 is also blocked by applying the maximum electrical control current I_st_2.1 to the clutch K2.1, which is consequently in its closed state. Alternatively, the process steps S1, S2, S3, and S4 can also be performed in a different sequence.

[0049] The control current I_st_1.1 for the selected coupling K1.1 is then set to a value greater than zero, which is held constant for a defined period of time (process step S5). In this state, the output shaft W1 is connected to the running drive motor 22 via the selected coupling K1.1.

[0050] With the control current I_st_1.1 remaining constant, the output shaft W1 is disconnected from the drive connections downstream in the power flow. This disconnection is achieved by the coupling K2.1, whose control current I_st_2.1 is set to zero, thereby opening the coupling K2.1 (process step S6). This results in an acceleration of the output shaft W1 with an angular acceleration α > 0.

[0051] The control current I_st_1.1 is kept constant, causing the rotational speed n1 of the output shaft W1 to increase and, in particular, to reach the motor speed n_m of the drive motor 22. In a subsequent process step S7, the clutch K1.1 is actuated with the maximum control current I_st_1.1 and thereby brought into its closed state. During this process, the output shaft W1 rotates at the motor speed n_m of the drive motor 22. Subsequently, the clutch K2.1 is actuated with a fixed or set control current I_st_2.1 > 0 (process step S8), whereby the output torque of this clutch K2.1 is zero due to the blocked downstream output shaft W2.

[0052] Following process step S8, the control current I_st_1.1 of clutch K1.1 is set to I_st_1.1 = 0, thereby moving clutch K1.1 into its open state (process step S9). This results in a deceleration of the output shaft W1 with an angular acceleration α < 0. The fixed or set control current I_st_2.1 of clutch 2.1 is held constant until the output shaft W1 reaches a rotational speed n1 = 0 (process step S10).

[0053] With the described process steps S1 to S10, the selected coupling K1.1 and the coupling unit or coupling K2.1 downstream of the output shaft in the power flow are controlled in a specific manner and successively for specific durations in order to realize suitable acceleration and deceleration sequences on the output shaft W1.

[0054] After process step S10, the process can be restarted to define or set other values ​​of the control stream I_st_1.1 and / or the control stream I_st_2.1 in process steps S5 and / or S8.

[0055] The following parameters are particularly relevant for generating calibration data β for the selected coupling K1.1: the fixed or set control currents I_st_1.1, I_st_2.1, the rotational speeds n1 of the output shaft W1 detected by means of the speed sensor 56 and the angular acceleration α of the output shaft W1 determined from this, the moment of inertia J1 of the output shaft W1 known by calculation, the set rotational speed n_m of the drive motor 22, the gear ratio R1.1.

[0056] These quantities or their values ​​are assigned to each other to generate the calibration data β depending on this assignment.

[0057] The following equations apply to the calibration data β = (β1, β2, β3, β4) for the selected coupling K1.1. X 1 = n 1 2 X 2 = n 1 − n _ m ⋅ R 1.1 2 X 3 = I _ st _ 1.1 X 4 = I _ st _ 2.1

[0058] Starting with equations GI. 2 to GI. 5, equation GI. 1 is calculated. This yields the result vector β. The following applies: β 1 = f 1 / J 1 β 2 = f 2 / J 1 β 3 = M 1 / J 1 β 4 = M 2 / J 1

[0059] The components β1 and β2 can be considered as physical correction quantities.

[0060] The component β1 contains a factor f1, which includes the sum of the drag torque M_s2 to the couplings K2.1 to K2.3 and the friction torque M_r, i.e. f1 = -(M_s2-M_r).

[0061] The component β2 contains a factor f2 = - M_s1, which includes the drag torque M_s1 to the couplings K1.1 to K1.3.

[0062] The torque M1 results from β3 · J1 for the clutch K1.1 at a control current I_st_1.1 determined or set by the control unit 52. The torque M2 results from β4 · J1 for the clutch K2.1 at a control current I_st_2.1 determined or set by the control unit 52.

[0063] The aforementioned procedure steps for calibrating a selected coupling, e.g., coupling K1.1, can be repeated for differently defined values ​​of the control currents I_st_1.1 and I_st_2.1, so that the calibration data β, in particular component β3, contains a torque M1 of coupling K1.1 for different control currents I_st_1.1. In other words, the calibration data β, in particular component β3, represents a torque characteristic of coupling K1.1. This torque characteristic can be provided as a complete characteristic curve using the calibration data β, in particular component β3.

[0064] The calibration data β can in principle be generated for any couplings K1.1 to Km.3 within the drive train 20 or the transmission arrangement 30.

[0065] In the practical application of the generated and provided calibration data β, for example, the clutch K1.1 is controlled by the control current I_st_1.1 in the direction of the open state until a state of "initial clutch slippage" is reached. Depending on the value of the control current I_st_1.1 in this state, the torque M1, and in particular frictional torques and drag torques, can be controlled at the clutch K1.1 using the provided calibration data β, in particular β3. β1 and β2,This can be determined, which in turn allows the determination of a torque acting at a specific position of the drive train 20. Depending on the value of the control current I_st_2.1 in this state, the torque M2 at the coupling K2.1 can be determined using the provided calibration data β, in particular β4, especially taking into account frictional torques and drag torques according to β1 and β2, to be determined.

[0066] This allows the provided calibration data β to support, for example, drive management (e.g. traction assistance) for the towing vehicle 10.

Claims

1. Method for calibrating a selected clutch (K1.1) which, arranged within a drivetrain (20) of an agricultural towing vehicle (10), is activatable between a closed and an open state, wherein - the selected clutch (K1.1) is connected in terms of drive on the drive side to a running drive motor (22) of the agricultural towing vehicle (10) and is connected in terms of drive on the output side to an output shaft (Wm, W1), - the value of a physical variable (I_st_m.n, I_st_1.1) bringing about the clutch activation is defined, wherein the physical variable activating the clutch (Mm.n, K1.1) is an electrical control current (I_st_m.n, I_st_1.1) of a hydraulic valve (54) activating the clutch (Km.n, K1.1), and a physical variable (α) representing the rotation of the output shaft (Wm, W1) is determined and assigned to the value of the physical variable (I_st_m.n, I_st_1.1) bringing about the clutch activation, in order to generate calibration data (β) of the selected clutch (Km.n, K1.1) depending on said assignment, characterized in that the physical variable representing the rotation of the output shaft (Wm, W1) is an angular acceleration (α) of the output shaft (Wm, W1).

2. Method according to Claim 1, characterized in that the method is carried out successively for differently defined values of the physical variable (I_st_m.n, I_st_1.1) bringing about the clutch activation.

3. Method according to Claim 1 or 2, characterized in that the angular acceleration (α) of the output shaft (Wm, W1) - has an acceleration phase brought about by the activation of the selected clutch (Km.n, K1.1), and - has a deceleration phase which is at least temporarily brought about by the activation of a clutch unit (Km+1.n, K2.1) following downstream in the power flow of the drivetrain (20).

4. Method according to any one of the preceding claims, characterized in that a moment of inertia (Jm, J1) of the output shaft (Wm, W1) is contained in the calibration data (β).

5. Method according to any one of the preceding claims, characterized in that the calibration data (β) contain at least one physical correction variable (β1, β2) which - comprises a drag torque (M_sm, M_s1) of the selected clutch (Km.n, K1.1), and / or - comprises a drag torque (M_sm+1, M_s2) of a clutch unit (Km+1,n, K2.1) following downstream of the output shaft (Wm, W1) in the power flow of the drivetrain (20), and / or - comprises a friction torque (M_r) of the output shaft (Wm, W1).

6. Method according to any one of the preceding claims, characterized in that, for the generation, in particular determination, at least one of the following steps is carried out: - the output shaft (Wm, W1) is separated from all drive connections (Km.n, Km+1.n, K1.1, K2.1) mounted upstream and downstream in the power flow of the drivetrain (20), - the output shaft (Wm, W1) is accelerated by being connected in terms of drive to the drive motor (22) and being separated from the drive connections (Km+1.n, K2.1) mounted downstream in the power flow of the drivetrain (20), - the output shaft (Wm, W1) which is connected in terms of drive to the drive motor (22) rotates at a rotational speed (n_m, n1, n_motor), in particular constant rotational speed (n_m, n1, n_motor), - the rotating output shaft (Wm, W1) is decelerated by activating a clutch unit (Km+1.n, K2.1) following downstream in the power flow of the drivetrain (20) with a defined value of a physical variable (I_st_m+1.n, I_st_2.1) bringing about the clutch activation thereof, wherein an output-side torque of said clutch unit (Km+1.n, K2.1) is equal to zero.

7. Method according to Claim 6, characterized in that, during the deceleration of the rotating output shaft (Wm, W1), the selected clutch (Km.n, K1.1) is in its open state.

8. Method according to Claim 6 or 7, characterized in that, at least during the deceleration of the output shaft (Wm, W1), a parking lock (64) and / or a braking device (66) of the towing vehicle (10) is activated.

9. Method according to any one of the preceding claims, characterized in that the motor rotational speed (n_motor) of the drive motor (22) is kept constant at least temporarily during the carrying out of the method.

10. Device (50) for calibrating a selected clutch (Km.n, K1.1) which, arranged within a drivetrain (20) of an agricultural towing vehicle (10), is activatable between a closed and an open state, with a control unit (52) for carrying out the method according to any one of Claims 1 to 9.

11. Device according to Claim 10, characterized in that it - has a hydraulic valve (54) for activating the selected clutch (Km.n, K1.1) between a closed and an open state, and / or - has a rotational speed sensor (56) for detecting a rotational speed (n_m, n1) of an output shaft (Wm, W1), which is connected in terms of drive to the selected clutch (Km.n, K1.1) on the output side thereof.

12. Agricultural towing vehicle (10) having a device (50) according to Claim 10 or 11.