METHOD FOR TRACTION-RELATED CONTROL OF A DRIVELINE OF A WORKING MACHINE

Abstract

A method for the traction-related control of a drive-train of a working machine (1) which has a drive unit (2), a transmission (3), a control unit (10) and first and second vehicle axles (7, 9) with rotatable wheels (6, 8). At least one of the vehicle axles (7, 9) is driven, and as a function of a specification either a first function (A) or a second function (B) is implemented. The first function (A) implements slip-orientated loading control and the second function (B) implements traction-efficiency control of the drive-train of the working machine (1).

Claims

1-10. (canceled)

11. A method for traction-related control of a drive-train of a working machine (1) having a drive unit (2), a transmission (3), a control unit (10) and first and second vehicle axles (7, 9) with wheels (6, 8), the method comprising: driving at least one of the vehicle axles (7, 9), implementing either a first function (A) or a second function (B) as a function of a specification, and implementing a slip-orientated loading control with the first function (A) and implementing a traction-efficiency control of the drive-train of the working machine (1) with the second function (B).

12. The method according to claim 11, further comprising after activating the first function (A): first determining an actual value of loading of the drive-train and an actual value of slip at the wheels (6, 8); reducing the actual value of the slip at the wheels (6, 8) by reducing drive output rotational speed of the transmission (3) until the actual value of the loading of the drive-train falls below a maximum value of the drive-train loading; then comparing the actual value of the drive-train loading with a target value of the drive-train loading, and initiating an increase of the slip at the wheels (6, 8) if the actual value of the drive-train loading differs from the target value of the drive-train loading; reducing slip at the wheels (6, 8) when the actual value of the drive-train loading corresponds to the target value of the drive-train loading; and following each increase or decrease of the drive output rotational speed of the transmission (3) with a check to confirm acceptable slip values.

13. The method according to claim 11, further comprising after activating the second function (B): first determining a characteristic value for characterizing an operating condition of the working machine (1); increasing a drive output rotational speed of the transmission (3), then determining a temporary characteristic value for characterizing an operating condition of the working machine (1); comparing the characteristic value and the temporary characteristic value and replacing the characteristic value with the temporary characteristic value if the temporary characteristic value is larger than the characteristic value, after which increasing the drive output rotational speed of the transmission (3), and again comparing the characteristic values, until the temporary characteristic value is smaller than or equal to the characteristic value; then reducing the drive output rotational speed of the transmission (3) and repeating the determination of a temporary characteristic value; thereafter comparing the characteristic value with the temporary characteristic value and replacing the characteristic value with the temporary characteristic value if the temporary characteristic value is larger than the characteristic value, after which the drive output rotational speed of the transmission (3) is reduced again and the characteristic values are compared again until the temporary characteristic value is smaller than or equal to the characteristic value; and the system then reverts to the increase of the drive output rotational speed of the transmission (3) and the previous steps are repeated.

14. The method according to claim 13, further comprising specifying a weighting for the calculation of the characteristic value by at least one of an operator and an external interface.

15. The method according to claim 11, wherein the specification to implement at least one of the first and the second function (A, B) takes place by way of an input by an operator.

16. The method according to claim 11, wherein the specification to implement at least one of the first and the second function (A, B) takes place in accordance with preferences stored in the control unit (10).

17. The method according to claim 11, further comprising, carrying out the first function (A) independently of a previously set specification, if, when the second function (B) is implemented, a minimum driving speed falls below or cannot exceed a threshold value.

18. The method according to claim 11, further comprising emitting a signal to reduce a traction force demand if, when implementing the first function (A) and the second function (B), the driving speed falls below a minimum threshold value.

19. The method according to any claim 11, further comprising enabling a weighting in favor of one of the first and the second functions (A, B) to be entered by at least one of an operator and an external interface, so that one of the first and the second functions (A, B) has a higher priority with regard to its implementation.

20. A working machine (1) with a drive unit (2), a transmission (3) and a control unit (10), wherein a drive power is introduced into the transmission (3) by way of a driveshaft (4) and the resulting drive power is transmitted, via a drive output shaft (5), to wheels (6, 8) of at least one of first and second vehicle axles (7, 9), and the control unit (10) being configured to carrying out the method according to the invention in accordance with claim 11.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0028] The invention will be explained with reference to the following figures, which show:

[0029] FIG. 1: A schematic representation of a working machine with an attachment;

[0030] FIG. 2a: In a schematic representation, a flow chart of the first function of the method for traction-related control of a drive-train of a working machine;

[0031] FIG. 2b: In a schematic representation, a flow chart of the second function of the method for traction-related control of a drive-train of a working machine.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0032] FIG. 1 shows in greatly simplified schematic form a working machine 1 with an attachment 11. The working machine 1 in this case is in the form of a tractor or farming tractor and has a drive unit 2, a transmission 3 and a control unit 10. The drive unit is connected by a driveshaft 4 to an input of the transmission 3, while an output of the transmission 3 is connected by way of a drive output shaft 5 to a first vehicle axle 7 or the wheels 6 fitted on it. The drive unit 2 supplies a drive power, which is passed by way of the driveshaft 4 into the transmission 3 and, in accordance with the gear ratio set, is transmitted by way of the drive output shaft 5 to the first vehicle axle 7. In this case the working machine 1 has a second vehicle axle 9, on which wheels 8 are fitted. The second vehicle axle 9 can likewise be connected to the drive output shaft 5 or to the first vehicle axle 7, and correspondingly all the wheels 6, 8 of the working machine 1 will then be driven wheels.

[0033] The control unit 10 is connected to transmit signals to the transmission 3 and/or the drive unit 2, as illustrated by the broken lines. Moreover, the control unit 10 comprises a sensor or measuring device (not shown) for detecting a driving speed of the working machine 1. Instead of being integrated in the control unit 10, the sensor can also be a separate component with a signal-transmitting connection.

[0034] In this case the attachment 11 is in the form of a plow. In alternative embodiments it can also be any other agricultural attachment for working the soil or for harvesting crops. In the simplest version it can also be a trailer. By means of a lifting device 13, the height of the attachment 11, in particular the plow, can be adjusted. Depending on the lifting height of the attachment 11 set, a sinking depth into the ground 12 changes. In particular, the ground 12 is a surface of an agriculturally useful area. In alternative versions, however, the ground 12 can also be a path or a road and in such cases usually attachments 11 other than the plow of the present example are connected to the working machine 1. By embedding the attachment 11 in the ground 12, the latter is broken up or raised, as illustrated by a raised area 14.

[0035] In FIG. 2a, in a schematic representation a flow chart of a first function A for the traction-related control of a drive-train of a working machine 1 is shown. Here, in a first process step A1 the first function A according to the invention is activated. In a second process step A2, an actual value of the loading of the drive-train and an actual value of the slip at the wheels 6, 8 are determined.

[0036] In a third process step A3, the actual value of the loading of the drive-train is compared with a maximum value of the loading of the drive-train. As long as the actual loading value is greater than or equal to the maximum value concerned, in a fourth process step A4 the slip at the wheels 6, 8 is reduced. This is done either by changing the gear ratio of the transmission 3 and/or by reducing the rotational speed of the drive unit 2, but in both cases the drive output rotational speed of the transmission 3 is reduced. In a fifth process step A5 a specification for reducing the value of the slip at the wheels 6, 8 is triggered. This should be understood to mean that the reduction in the fifth process step A5 is specified dynamically as a constant value, for example as a percentage fraction of the deviation or of the loading, or as a function of further factors (such as the driving speed, the gear ratio set in the transmission 3, etc.) with reference to a characteristic diagram or an algorithm. In addition, a comparison is carried out to see whether with the change, an acceptable slip value is reached, the slip is consequently not below a lower threshold value, and an upper threshold value for the slip is not exceeded.

[0037] The sequence of the second, third, fourth and fifth process steps A2, A3, A4, A5 is repeated in a loop until in the third process step A3 the actual value of the loading is smaller than the maximum value concerned. This is followed by a sixth process step A6 in which a comparison of the actual loading value with a target value of the loading takes place. So long as the actual loading value does not correspond to a target loading value, in a seventh process step A7 the slip at the wheels 6, 8 is increased. This is done by increasing the drive output rotational speed of the transmission 3. The process then reverts to the fifth process step A5 and a new run from the second process step A2 takes place. The target value of the loading can in the process be specified as an exact value or a defined value range.

[0038] If in the sixth process step A6 it is found that the actual value of the drive-train loading matches the target value of the drive-train loading, then in an eighth process step A8 the actual value of the slip at the wheels 6, 8 is reduced by reducing the drive output rotational speed of the transmission 3. After passing through the fifth process step A5, the function A according to the invention begins afresh with the second process step A2. In other words by virtue of the first function A, a permanent traction-related or slip-related loading regulation of the working machine 1 or its drive-train takes place. By virtue of the continuous repetition through process steps A1 to A8 in the above-described sequence, it is possible in a simple manner to react to changing environmental conditions, in particular changing traction resistances due to different surface conditions of the ground 12.

[0039] In a manner similar to FIG. 2a above, FIG. 2b shows a schematic representation of a flow chart, but in this case that of a second function B for the traction-related control of a drive-train of a working machine 1. In a first process step B1, the second function B according to the invention is activated. In a second process step B2, a characteristic value is determined, which characterizes an operating condition of the working machine 1 or its drive-train at the beginning of the second function B. In a third process step B3 the drive output rotational speed of the transmission 3 is increased, after which in a fourth process step B4 the characteristic value is recalculated. That characteristic is taken as a temporary characteristic value.

[0040] In a fifth process step B5 the temporary characteristic value is compared with the characteristic value determined in the second process step B2. So long as the temporary characteristic is larger than the characteristic calculated in the second process step B2, in a sixth process step B6 the temporary characteristic replaces the characteristic calculated in the second process step B2 and the system reverts to the third process step B3. The process steps B3 to B6 are repeated cyclically until it is found in the fifth process step B5 that the temporary characteristic is smaller than or identical to the characteristic value calculated in the second or the sixth process step B2, B6.

[0041] When that is the case, in a seventh process step B7 the drive output rotational speed of the transmission 3 is reduced. Analogously to the increase of the drive output rotational speed of the transmission 3 in the third process step B3, this is done by adapting the rotational speed/torque of the drive unit 2 and/or by adapting the gear ratio of the transmission 3. Then, in an eighth process step B8 a temporary characteristic value is again determined. In a ninth process step B9 the temporary characteristic is again compared with the characteristic from the fifth process step B5. If the temporary characteristic is larger than the characteristic from the fifth process step B5, then in a tenth process step B10 the temporary characteristic replaces the characteristic from the fifth process step B5 and the system reverts to the seventh process step B7 as the input magnitude.

[0042] The process steps B7 to B10 are repeated cyclically until it is found in the ninth process step B9 that the temporary characteristic is smaller than or identical to the characteristic from the fifth process step B5. Only then does the system revert to the third process step B3 and the function sequence begins afresh from there in the previously described sequence of process steps B3 to B10.

[0043] The control unit 10 shown in FIG. 1 is suitable and designed to carry out the first and/or the second function A, B for the traction-related control of the drive-train of the working machine 1. For that purpose an input device (not shown) can be provided, by means of which an operator chooses whether to carry out the first or second function A, B. Furthermore, in a further design the control unit 10 can alternatively or additionally be suitable and designed to change between the first and second functions A, B for the optimum operation of the working machine 1. This can also include the approval of a choice of the operator's to implement the first or second functions A, B. Likewise, it can be provided that a choice by the operator is in agreement with a choice by the control unit 10.

INDEXES

[0044] 1 Working machine [0045] 2 Drive unit [0046] 3 Transmission [0047] 4 Driveshaft [0048] 5 Drive output shaft [0049] 6 Wheel [0050] 7 First vehicle axle [0051] 8 Wheel [0052] 9 Second vehicle axle [0053] 10 Control unit [0054] 11 Attachment [0055] 12 Roadway [0056] 13 Lifting device [0057] 14 Raised area [0058] A First function [0059] A1-A8 Process steps of the first function [0060] B Second function [0061] B1-B10 Process steps of the second function