DRIVETRAIN OF A VEHICLE AND METHOD FOR OPERATING A DRIVETRAIN OF A VEHICLE

Description

[0001] The present invention relates to a drive train of an agricultural or municipal work machine, wherein the drive train comprises a drive motor, a transmission and at least one first coupling device.

[0002] When operating the drive train of an agricultural or municipal work machine, situations can arise during starting and / or reversing in which an increase in load can cause a drive engine designed as an internal combustion engine to stall. Particularly during heavy pulling work or when the engine is too weak in relation to a towed and driven attachment, there is a risk that the drive engine will stall during starting or reversing if the load increases too much.

[0003] DE 39 26 716 A1 discloses a drive train for an agricultural machine, comprising a controllable internal combustion engine and a continuously variable transmission. There is no clutch between the internal combustion engine and the transmission. When the machine starts moving, the engine speed is reduced to improve the overall efficiency of the power-split transmission.

[0004] EP 1 144 886 B1 relates to a method for actuating, in particular, a reversing clutch device for reversing the direction of travel, which is also operated in a slipping mode, the so-called inching function. The method automatically limits the frictional power to protect the clutch. For this purpose, the frictional power and the temperature of the clutch device are automatically influenced by an automatic control or regulation of the continuously variable transmission ratio depending on one or more parameters. For work machines designed as tractors, a variation in the engine speed is excluded due to the constant PTO speed required when necessary.

[0005] DE 102 30 651 A1, DE 10 2012 208 443 A1 and DE 36 06 229 A1 disclose further drive trains with a coupling between the engine shaft and the gearbox, whereby the engine speed is regulated during starting.

[0006] Based on the prior art described above, the object of the invention is to provide a drive train of an agricultural or municipal work machine and a method for operating a drive train of an agricultural or municipal work machine, which prevent a drive motor in the drive train from stalling when starting or reversing.

[0007] This object is achieved in terms of device technology by a drive train having the features of claim 1 and by an agricultural or municipal work machine having a drive train having the features of the independent claim 11, and in terms of process technology by a method for operating a drive train of an agricultural or municipal work machine having the features of the independent claim 12. Advantageous developments of the invention are the subject of the dependent claims.

[0008] According to claim 1, a drive train of an agricultural or municipal work machine is proposed, the drive train comprising a drive motor, a transmission and at least one first clutch device. In particular, the transmission can be designed as a powershift transmission. In order to prevent the drive motor from stalling when starting or reversing, the invention provides that the drive train comprises at least one control device which is designed to temporarily increase an engine speed provided by the drive motor during a starting process and / or a reversing process as a function of at least one operating parameter of the drive train. By temporarily increasing the engine speed of the drive motor, stalling of the drive motor when the engine load increases is prevented.This is particularly advantageous for low-powered agricultural machinery, as their drive motors do not have large torque reserves. In particular, the temporary increase in the engine speed of the drive motor occurs depending on at least one operating parameter of the first clutch device.

[0009] The first coupling device can be designed as a reversing coupling device. A change in the direction of travel can be achieved by means of the first coupling device designed as a reversing coupling device. The reversing coupling device can include a clutch for forward travel and a clutch for reverse travel. Both clutches of the reversing coupling device can be designed as hydraulically actuated multi-disk clutches.

[0010] According to the invention, the at least one operating parameter is a slip occurring at the first clutch device. Slip at the first clutch device always occurs during the starting or reversing process. By increasing the engine speed, in particular the idle speed, as a function of the slip as an operating parameter of the first clutch device, stalling of the drive engine can be prevented when the engine load increases if the slip of the first clutch device decreases during starting or reversing.

[0011] Preferably, the control device can be configured to determine the slip occurring at the first clutch device using data provided by speed sensors, wherein one speed sensor detects an input speed upstream of the first clutch device and at least one further speed sensor detects an output speed downstream of the first clutch device. For this purpose, the data from the speed sensors can be transmitted to the control device via a bus system, such as a CAN bus. Based on the CAN bus data, the control device can infer the occurrence of slip by evaluating it and calculate the current magnitude of the slip. In this way, the control device can determine a slip profile, depending on which the engine speed is controlled or regulated.Preferably, one speed sensor can detect the input speed at the input shaft of the transmission, while the other speed sensor detects the output speed, preferably immediately behind the first clutch device.

[0012] Furthermore, the at least one operating parameter can be a switching position of a reversing switch. The switching position of the reversing switch can also be determined by the control device based on corresponding CAN bus data transmitted via the CAN bus. A change in the switching position of the reversing switch is accompanied by a reversal of the direction of travel, for which the first clutch device is controlled accordingly. In response to this, the control device determines the slip occurring at the first clutch device in order to increase the engine speed by controlling the drive motor.

[0013] Furthermore, the at least one operating parameter can be a clutch pedal position. Based on the clutch pedal position, the control device can determine whether the first clutch is operating with friction slip. Furthermore, a further operating parameter can be a gear engaged on the transmission that was selected when starting or reversing. The information about the selected gear can also be determined by the control device based on existing CAN bus data. In this case, the data regarding the currently engaged gear on the transmission can be provided by a transmission control device, transmitted via the CAN bus, and evaluated by the control device.

[0014] In particular, the increase in the engine speed of the drive motor by actuating the control device can have a sudden initial increase. The initial increase can approximately follow the slip curve of the first clutch device determined by the control device.

[0015] Preferably, the control device can be configured to control the drive motor so that the initial curve of the engine speed transitions to a substantially constant curve, the duration of which depends on the slip of the first clutch device falling below a predeterminable limit value. This ensures that stalling of the drive motor is avoided even during the synchronization phase of the first clutch device.

[0016] Furthermore, the control device can be configured to reduce the increased engine speed to a drive speed required for operation after the slip value falls below the predeterminable limit. The drive speed required for operation can be the drive speed specific to the selected gear.

[0017] In addition, the control device can be configured to reduce the engine speed to the drive speed before synchronization of the clutch speed of the first clutch device has taken place.

[0018] The reduction can occur over an adjustable period of time. Alternatively, the engine speed can be reduced across the slip range. The gradual reduction in engine speed increases driving comfort.

[0019] In particular, the control device can be configured to increase the engine speed independently of a current vehicle speed and / or direction of travel.

[0020] According to claim 11, an agricultural or municipal work machine with a drive train is proposed, wherein the drive train is designed according to one of claims 1 to 10.

[0021] According to claim 12, a method for operating a drive train of an agricultural or municipal work machine is proposed, wherein the drive train comprises a drive motor, by which an engine speed is provided, which is transmitted to a downstream transmission, and at least one first clutch device, by which the transmission and at least one drive axle are drivingly connected to one another or separated from one another. In particular, the transmission can be designed as a powershift transmission. The method is characterized in that the drive train comprises at least one control device, by which the drive motor is controlled, so that during a starting process and / or a reversing process, the engine speed of the drive motor is temporarily increased depending on at least one operating parameter, wherein the at least one operating parameter is a slip occurring at the first clutch device.The process can be easily integrated into the drive train control system.

[0022] According to a preferred development, the slip of the clutch device can be determined as at least one operating parameter by the control device using data provided by speed sensors, with one speed sensor detecting an input speed upstream of the first clutch device and at least one further speed sensor detecting an output speed downstream of the first clutch device. By using existing speed sensors, the slip can be determined with sufficient accuracy by the control device without the need for additional sensors.

[0023] Preferably, the increase in the engine speed of the drive motor controlled by the control device can follow a speed curve that has a sudden initial increase, and the initial engine speed curve transitions into a substantially constant curve section, the duration of which depends on the slip of the first clutch device falling below a predeterminable limit value. Advantageously, no additional sensors are required to determine any slip occurring at the first clutch device.

[0024] The present invention is explained in more detail below with reference to an embodiment shown in the drawings.

[0025] They show: Fig. 1 shows a schematic and exemplary representation of a drive train of a vehicle; and Fig. 2 shows a diagram showing a slip curve of a first clutch device and a speed curve of a drive motor of the drive train.

[0026] In Fig. 1 A schematic and exemplary representation of a drive train 1 of a vehicle is shown. The vehicle is, in particular, an agricultural or municipal work machine, particularly preferably a tractor. The drive train 1 comprises a drive engine 2 and a transmission 3. In work machines, in particular tractors, a transmission 3 designed as a so-called powershift transmission, for example a partial load transmission (partially powershift transmission) or a full load transmission (fully powershift transmission), is often used to transmit torque from the drive unit to the drive.

[0027] The transmission 3 is connected on the output side to an axle drive 5 by a first coupling device 4. The first coupling device 4 is, in particular, a reversing coupling device for changing the direction of travel of the work machine without interrupting the tractive force. The first coupling device 4 allows switching between forward and reverse travel without interrupting the power connection between the drive motor 2 and the axle drive 5. The first coupling device 4 can also be designed as a starting clutch. A drive movement of the drive motor 2, transmitted by the transmission 3, is distributed to two drive wheels 7 on a drive axle 6 via the axle drive 5.

[0028] At least two speed sensors 8 and 9 are provided, of which the speed sensor 8 detects an input speed upstream of the first clutch device 4, and the at least one further speed sensor 9 detects an output speed downstream of the first clutch device 4. The speed sensors 8, 9 transmit signals to a control device 10 via a bus system 11, for example a CAN bus. The control device 10 is configured to evaluate the signals received from the speed sensors 8, 9.

[0029] A clutch pedal 12 and a reversing switch 13 are provided for actuating the clutch device 4. The actuation and pedal position of the clutch pedal 12 are detected by sensors, for example, by a rotary potentiometer, and transmitted to the control device 10 via the bus system 11. Based on the pedal position and the duration for which the clutch pedal 12 is held in a specific position, the control device 10 is able to detect whether the clutch device is operating in slipping mode (inching function). The actuation of the reversing switch 13 by a vehicle operator is also transmitted to the control device 10 via the bus system 11.

[0030] A transmission control device 14 is assigned to the transmission 3 and serves to control the transmission 3. The transmission control device 14 is connected to the control device 10 via the bus system 11. This provides the control device 10 with, among other things, information about the currently selected gear and the drive speed specific to the selected gear.

[0031] When operating the drive train 1, situations may arise during starting and / or reversing in which the drive motor 2 may stall due to an increase in load. Particularly during heavy pulling work or when the motor is too weak in relation to a towed and driven attachment, there is a risk that the drive motor 2 will stall during starting or reversing if the load increases too much. To counteract this, the at least one control device 10 in the drive train 1 is configured to temporarily increase an engine speed provided by the drive motor 2 during a starting process and / or a reversing process depending on at least one operating parameter of the drive train 1.

[0032] For this purpose, the control device 10 determines a slip occurring at the first clutch device 4 as at least one operating parameter. The slip is calculated using the data transmitted from the speed sensors 8 and 9 to the control device 10 via the bus system 11. Further operating parameters are the switching position of the reversing switch 13 and the pedal position of the clutch pedal 12. Actuation of the reversing switch 13 is evaluated accordingly by the control device 10, so that the control device 10 has information about a change in direction of travel, which is accompanied by a corresponding control of the drive motor 2. The information about the gear selection as an operating parameter can also be taken into account by the control device 10 when controlling the drive motor 2.The drive speed to be provided by the drive motor 2 can be determined using the information about the gear selection when starting or reversing.

[0033] In Fig. 2 1 shows an example of a diagram showing a slip curve 15 of the first clutch device 4 and a speed curve 16 of the drive motor 2 of the drive train 1. During a start-up process, the first clutch device 4 is closed, whereby slip occurs due to the speed difference. At a time t 0 , the vehicle starts moving from a standstill. The drive motor 2 is operated at an idling speed n Leer . The slip curve has an initial maximum value, which decreases over time. After synchronization of the first clutch device 4, slip generally no longer occurs.

[0034] To prevent the drive motor 2 from stalling, the engine speed of the drive motor 2 is increased by controlling the control device 10 after the occurrence of slip has been determined at time t 0. In the exemplary embodiment shown, the engine speed is increased starting from the idle speed n Leer. In principle, the increase in the engine speed by controlling the drive motor 2 by the control device 10 can take place independently of the current vehicle speed and / or the direction of travel. The speed curve 16 has a sudden initial increase. At time t 1, the speed increase ends and the speed curve 15 transitions to a substantially constant curve. It would be conceivable to initiate a slight reduction in the engine speed at this point by appropriately controlling the drive motor 2 by the control device 10.The magnitude of the increase and the duration of the increase in engine speed are determined as a function of the slip curve 15 calculated by the control device 10.

[0035] From a time t 2 the engine speed is reduced. The reduction in engine speed can be based on the gear of the transmission 3 selected or specified for the start-up process. The reduction in the temporarily increased engine speed can occur once the slip falls below a predeterminable limit value S limit. The increased engine speed is reduced to a drive speed required for operation. The length of the interval between time t 1 and time t 2 , within which the increased engine speed is kept essentially constant, can also be determined as a function of the slip. It is also conceivable, however, to specify the interval so that the increase in speed is maintained over a defined slip range. Reducing the engine speed before synchronization of the clutch device 4 improves driving comfort.

[0036] Preferably, by controlling the drive motor 2 by the control device 10, the motor speed can be reduced to the drive speed before synchronization of the clutch speed of the first clutch device 4 has taken place. List of reference symbols

[0037] 1Drivetrain 2Drive motor 3Gearbox 4First clutch 5Axle transmission 6Driven axle 7Wheels 8Speed ​​sensor 9Speed ​​sensor 10Control device 11Bus system 12Clutch pedal 13Reversing switch 14Gearbox control device 15Slip curve 16Speed ​​curve n Idle Idle speed S Limit Limit value for slip t 0 Time t 1 Time t 2 Time

Claims

1. A drive train (1) of an agricultural or municipal working machine comprising a propulsion engine (2), a transmission (3) as well as at least one first clutch device (4), characterized in that the drive train (1) comprises at least one control device (10) which is configured, in the case of a start-up procedure and / or a reversing procedure, to temporarily increase an engine speed (nidle) made available by the propulsion engine (2) as a function of at least one operating parameter of the drive train (1), wherein the at least one operating parameter is a slippage occurring at the first coupling device (4).

2. The drive train (1) according to claim 1, characterized in that the first coupling device (4) is constructed as a reversing clutch device.

3. The drive train (1) according to claim 1 or claim 2, characterized in that the control device (10) is configured to determine the slippage occurring at the first coupling device (10) by means of data provided from speed sensors (8, 9), wherein one speed sensor (8) detects an input speed in front of the first clutch device (10) and at least one further speed sensor (9) detects an output speed after the first clutch device (10).

4. The drive train (1) according to one of the preceding claims, characterized in that the at least one operating parameter is a gear shift position of a reversing gear shift (13).

5. The drive train (1) according to one of the preceding claims, characterized in that the at least one operating parameter is a pedal position of a clutch pedal (12).

6. The drive train (1) according to one of the preceding claims, characterized in that the increase in the engine speed of the propulsion engine (2) by the control of the control device (10) has an abruptly rising initial profile.

7. The drive train (1) according to claim 6, characterized in that the control device (10) is configured to control the propulsion engine (2) so that the initial profile of the engine speed merges into a substantially constant profile the time duration of which is a function of falling below a predeterminable threshold value (Sthreshold) for the slippage of the first clutch device (4).

8. The drive train (1) according to claim 7, characterized in that the control device (10) is configured such that, after falling below the predeterminable threshold value (Sthreshold) for the slippage, the increased engine speed is reduced to a drive speed which is necessary for the operation.

9. The drive train (1) according to claim 8, characterized in that the control device (10) is configured such that the engine speed is reduced to the drive speed before a synchronisation of the clutch speed of the first clutch device (4) has been carried out.

10. The drive train (1) according to one of the preceding claims, characterized in that the control device (10) is configured to carry out the increase of the engine speed independently of a current vehicle speed and / or direction of travel.

11. An agricultural or municipal working machine with a drive train (1), characterized in that the drive train (1) is constructed in accordance with one of claims 1 to 10.

12. A method for operating a drive train (1) of an agricultural or municipal working machine comprising a propulsion engine (2) via which an engine speed is made available which is transmitted to a downstream transmission (3), at least one first clutch device (4) via which the transmission (3) and at least one drive axle (6) of the vehicle are operatively connected together or operatively separated from each other, characterized in that the drive train (1) comprises at least one control device (10) via which the propulsion engine (2) is controlled, in that, in the case of a start-up procedure and / or a reversing procedure, the engine speed of the propulsion engine (2) is temporarily increased as a function of at least one operating parameter, wherein the at least one operating parameter is a slippage occurring at the first clutch device (4).

13. The method according to claim 12, characterized in that the slippage of the clutch device (4) as the at least one operating parameter is determined by the control device (10) by means of data provided from speed sensors (8, 9), wherein one speed sensor (8) in front of the first clutch device (4) detects an input speed and at least one further speed sensor (9) after the first clutch device (4) detects an output speed.

14. The method according to claim 12 or claim 13, characterized in that the increase of the engine speed of the propulsion engine (2) carried out by the control device (10) follows a speed profile (16) which has an abruptly rising initial profile and in that the initial profile of the engine speed merges into a substantially constant profile section the time duration of which is a function of falling below a predeterminable threshold value (Sthreshold) for the slippage of the first clutch device (4).