METHOD FOR CONTROLLING A DRIVING DYNAMICS FUNCTION OF A WORKING MACHINE

Abstract

A method for controlling a driving dynamics function of a working machine with at least two vehicle axles. A current actual wheel rotational speed of at least one wheel is detected and sent to a control unit for comparison with an acceptable wheel rotational speed of the same wheel and wheel slip is calculated from that comparison. The control unit emits a control signal to lock at least one differential gear system if the wheel slip has an unacceptable value. For the differential gear system (4, 5, 6, 7, 8) concerned, an unlocking control signal is periodically emitted and the wheel rotational speeds are compared afresh. A control signal to lock the differential gear system concerned is emitted again if the value of the wheel slip is still unacceptable, and a trajectory is detected with reference to detection elements, along which the value of the wheel slip of the at least one wheel has been unacceptable.

Claims

1-10. (canceled)

11. A method for controlling a driving dynamics function of a working machine with at least two vehicle axles (I, II, III), the method comprising: detecting and sending a current actual wheel rotational speed of at least one wheel (R1, R1′, R2, R2′, R3, R3′) to a control unit for comparison with an acceptable wheel rotational speed of the same wheel (R1, R1′, R2, R2′, R3, R3′), and calculating a wheel slip from such comparison, the control unit emits a control signal to lock at least one differential gear system (4, 5, 6, 7, 8) if the wheel slip has an unacceptable value, for the differential gear system (4, 5, 6, 7, 8) concerned an unlocking control signal is emitted periodically and the wheel rotational speeds are compared afresh, and again emitting a control signal to lock the differential gear system (4, 5, 6, 7, 8) concerned if the value of the wheel slip is still unacceptable, and with reference to detection means (S1, S1′, S2, S2′, S3, S3′) a trajectory is detected, along which the value of the wheel slip of the at least one wheel (R1, R1′, R2, R2′, R3, R3′) has been unacceptable.

12. The method according to claim 11, further comprising, besides the trajectory itself, its position is determined, and in a predictive manner, before a further wheel (R1, R1′, R2, R2′, R3, R3′) covers the trajectory, emitting a control signal to lock the differential gear system (4, 5, 6, 7, 8) concerned for at least one further differential gear system (4, 5, 6, 7, 8).

13. The method according to claim 12, further comprising periodically emitting, for at least the further differential gear system (4, 5, 6, 7, 8), an unlocking control signal and carrying out another comparison of the wheel rotational speeds, and again emitting a control signal to lock the differential gear system (4, 5, 6, 7, 8) concerned if the value of the wheel slip is still unacceptable.

14. The method according to claim 13, further comprising adapting a value of a closing duration of the at least one locked differential gear system (4, 5, 6, 7, 8) having regard to further driving dynamics parameters (X), and the value resulting from a period length.

15. The method according to claim 12, further comprising, as a priority for the differential gear system (4, 5, 6, 7, 8) concerned, emitting an unlocking control signal and determining the wheel slip, at which unlocking would with high probability give expectation of an acceptable wheel slip value, and again emitting a control signal to unlock the differential gear system (4, 5, 6, 7, 8) if the value of the wheel slip is still unacceptable.

16. The method according to claim 15, further comprising, if an unacceptable wheel slip value is previously determined, deferring the periodic emission of the control signal to unlock the remaining differential gear systems (4, 5, 6, 7, 8).

17. The method according to claim 11, further comprising using a wheel rotational speed of at least one further wheel (R1, R1′, R2, R2′, R3, R3′) by the detection means (S1, S1′, S2, S2′, S3, S3′).

18. The method according to claim 11, further comprising a signal for the determination of position data which is used by the detection means (S1, S1′, S2, S2′, S3, S3′).

19. A working machine comprising: a drive-train (1) with a drive element (2), at least one differential gear system (4, 5, 6, 7, 8) that is lockable, at least two vehicle axles (I, II, III), and at least one wheel (R1, R1′, R2, R2′, R3, R3′) being fitted on each vehicle axle (I, II, III); detection means (S1, S1′, S2, S2′, S3, S3′); and a control unit designed for carry out the method according to claim 11.

20. A computer program product with a program code for carrying out the method according to claim 11 when the program code is run on a computer.

21. A method for controlling a driving dynamics function of a working machine having at least two vehicle axles (I, II, III), the method comprising: detecting and sending, to a control unit, a current actual wheel rotational speed of at least one wheel (R1, R1′, R2, R2′, R3, R3′) for comparison with an acceptable wheel rotational speed of that wheel (R1, R1′, R2, R2′, R3, R3′), calculating a wheel slip from such comparison, emitting, via the control unit, a control signal to lock at least one differential gear system (4, 5, 6, 7, 8) if the wheel slip has an unacceptable value, periodically emitted an unlocking control signal, for the differential gear system (4, 5, 6, 7, 8) concerned, again comparing the wheel rotational speeds and, if the value of the wheel slip is still unacceptable, again emitting a control signal to lock the differential gear system (4, 5, 6, 7, 8) concerned, and detecting a trajectory, via detection means (S1, S1′, S2, S2′, S3, S3′), along which a value of the wheel slip of the at least one wheel (R1, R1′, R2, R2′, R3, R3′) is unacceptable.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0024] The invention will be described in greater detail with reference to the following figures, which show:

[0025] FIG. 1: A schematic representation of a first drive-train of a working machine;

[0026] FIG. 2: A schematic representation of a second drive-train of a working machine;

[0027] FIG. 3: A schematic representation of a third drive-train of a working machine;

[0028] FIG. 4: A schematic representation of a fourth drive-train of a working machine;

[0029] FIG. 5: A simplified flow chart of the method according to the invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0030] FIG. 1 shows in greatly simplified and schematic form a drive-train 1 of a working machine. In this case the drive-train 1 comprises first, second and third vehicle axles I, II, III, wherein the first axle I is designed to be a front axle and the second and third axles II and III are rear axles. Arranged on the first vehicle axle there are two wheels R1, R1′, on the second vehicle axle II there are two wheels R2, R2′ and on the third vehicle axle III there are again two wheels R3, R3′. In addition, two detection means S1, S1′ are associated with the first vehicle axle I, two detection means S2, S2′ with the second vehicle axle II, and two detection means S3, S3′ likewise with the third vehicle axle III. In this case the detection means S1, S1′, S2, S2′, S3, S3′ are rotational speed sensors.

[0031] In addition the first vehicle axle I has a differential gear system 4, the second vehicle axle II a differential gear system 6 and the third vehicle axle III a differential gear system 7. The differential gear systems 4, 6, 7 are in this case in the form of transverse differential gear systems. Thus, they enable rotational speed equalization between the wheels R1, R1′, R2, R2′ and R3, R3′; of the respective vehicle axles I, II, III.

[0032] Furthermore, between the first and second vehicle axles I, II a differential gear system 5 is arranged and between the second and third vehicle axles II, III a differential gear system 8 is arranged. The two differential gear systems 5, 8 are in this case in the form of longitudinal differential gear systems and enable rotational speed equalization between the first and second vehicle axles I, II and the second and third vehicle axles II, III, respectively.

[0033] A drive element 2 provides the necessary drive power. The drive element 2 can in particular be in the form of an internal combustion engine. It is also conceivable, however, that it could be an electric motor. By means of broken lines, transmission devices 3 are represented. These are in particular driveshafts provided between the respective differential gear systems 4, 5, 6, 7, 8 and between the differential gear system 5 and the drive element 2. By means of the transmission devices 3 the rotational speed and the torque is transmitted. So long as the working machine and its drive-train 1 are moving in a forward travel direction F, the wheels R1, R1′ of the first vehicle axle I cover a particular trajectory whereas the wheels R2, R2′ of the second vehicle axle II cover the same stretch after a time interval. In the same way the wheels R3, R3′ of the third vehicle axle III cover the same stretch after a further interval. If now one of the detection means S1, S1′ of the first vehicle axle I identifies an unacceptable wheel rotational speed of one of the wheels R1, R1′, then the control unit (not shown here) emits a signal to lock the differential gear system 4. A similar process takes place if for one of the wheels R2, R2′ of the second vehicle axle II or one of the wheels R3, R3′ of the third vehicle axle III an unacceptable value of the wheel rotational speed is detected. Correspondingly, the differential gear system 6 and/or the differential gear system 7 is locked or a signal to lock those differential gear systems 6, 7 is emitted.

[0034] So long as for both wheels R, R1′, R2, R2′, R3, R3′ of a vehicle axle I, II, III an unacceptable wheel rotational speed value is detected at the same time, a signal to lock the differential gear system 5 and/or the differential gear system 8 is emitted and those differential gear systems 5, 8 are locked.

[0035] Since the distances between the vehicle axles I, II, III are not variable, if there is an unacceptable wheel rotational speed at one of the vehicle axles I, II, III it can be concluded that there is a traction reduction and this can be calculated if one of the later vehicle axles II, III passes over exactly the same area. Correspondingly, when this situation is reached or already shortly before, a signal to lock the differential gear system 6 or the differential gear system 7 is emitted.

[0036] Also not shown are further detection means, which for example are in the form of GPS sensors. These can be provided in addition to the existing detection means S1, S1′, S2, S2′, S3, S3′.

[0037] In the embodiment of the drive-train 1 illustrated here, the differential gear systems 4, 5, 6, 7, 8 are arranged centrally. This means that they are the same distance away from the left-hand and right-hand sides of the working machine. Furthermore, the second vehicle axle II is in the form of a so-termed drive-through axle. This means that the differential gear system 6, besides the rotational speed equalization at the second vehicle axle II, also ensures a drive-through to the differential gear system 8 and thereby also to the third vehicle axle III.

[0038] FIG. 2 shows a schematic representation of a second drive-train 1. This differs from the drive-train 1 described in FIG. 1, in that the differential gear systems 4, 5, 6, 7, 8 are this time no longer arranged centrally. Rather, relative to the travel direction F the differential gear systems 4, 6 and 7 are offset parallel to and by the same distance from the differential gear systems 5 and 8. Furthermore, the differential gear system 5 is now connected to the differential gear system 8 by way of the transmission devices 3, while the differential gear system 8 is connected via the transmission devices 3 to the differential gear system 6 and the differential gear system 7. From this it follows that the second vehicle axle II is no longer a drive-through axle. However, the method according to the invention can be carried out in the same way with the existing drive-train.

[0039] FIG. 3 shows a schematic representation of an alternative design and therefore a third drive-train 1. This differs from the embodiment described in FIG. 1 in that the differential gear system 8 between the second and third vehicle axles II, III is omitted. All the other elements of the drive-train 1 and their functional interconnections are the same as in the arrangement and functional mode described in FIG. 1.

[0040] FIG. 4 shows schematically a different version of the drive-train 1 in FIG. 2. In contrast to the embodiment shown in FIG. 1, the drive-train 1 shown in this case comprises a direct connection by way of transmission devices 3 between the differential gear system 6 and the differential gear system 5 and also the differential gear system 7 and the differential gear system 5. In all other respects the embodiments of the drive-train 1 shown in FIG. 2 and FIG. 4 are the same.

[0041] In general it should be noted that the wheels R1, R2, R3 are all arranged on the left-hand side of the working machine and the wheels R1′, R2′, R3′ are arranged on the right-hand side of the working machine.

[0042] FIG. 5 shows a greatly simplified flow chart of the method according to the invention. In a first step A, a signal to unlock the respective differential gear systems 4, 5, 6, 7, 8 is emitted. This signal can be emitted independently of any previous program or process sequence, in order to ensure that all the differential gear systems 4, 5, 6, 7, 8 are in an unlocked or open condition. Advantageously, the first process step A can also be carried out when the vehicle is started. Alternatively, it is also conceivable that the first process step A is suppressed when the vehicle is started, so that all the differential gear systems 4, 5, 6, 7, 8 remain in their last-set operating conditions.

[0043] In a second process step B, a rotational speed of at least one wheel R1, R1′, R2, R2′, R3, R3′ is determined. This is done in particular with reference to the detection means S1, S1′, S2, S2′, S3, S3′.

[0044] Thereafter, in a third step C a comparison is carried out between the rotational speed determined and an acceptable rotational speed. So long as the rotational speed determined corresponds to the acceptable rotational speed, having regard to a tolerance range of the acceptable rotational speed, the process reverts from the third process step C to the second process step B. In particular, the purpose of this is that periodically the corresponding wheel rotational speed is determined again and a comparison is carried out. In this, the time interval for the repeated carrying out of the determination and comparison of the wheel rotational speed, i.e. the period length, can be fixed or varied with reference to further parameters.

[0045] So long as in the third process step C it is found that the rotational speed determined has adopted or reached an unacceptable rotational speed value, in a fourth process step D a signal to lock the differential gear system 4, 5, 6, 7, 8 concerned is generated and emitted by a control unit (not shown here). In addition the process reverts from the fourth process step D to the first process step A. Due to the reversion between the fourth and first process steps D, A, it is ensured that the differential gear system 4, 5, 6, 7, 8 concerned remains in a locked condition only for as long as is necessary for optimum driving operation.

[0046] This reversion also takes place periodically. This at the same time means that the locking condition of the differential gear system 4, 5, 6, 7, 8 concerned produced in the fourth process step D persists during a certain time interval before a signal to unlock the differential gear system 4, 5, 6, 7, 8 is emitted in the first process step A. The period length after which the change from the fourth process step D to the first process step A takes place, can be influenced by driving dynamics parameters X. Thus, such driving dynamics parameters X can in particular contribute toward shortening a specified period length. In particular this happens when the working machine begins driving round a curve or when a limit value for a curve radius is reached or exceeded, at which limit a locked differential gear system 4, 5, 6, 7, 8 has a disadvantageous influence on the driving dynamics of the working machine.

[0047] The sequence for the method according to the invention described in FIG. 5 pictures the determination of a wheel rotational speed, and if the wheel rotational speed is unacceptable, a differential gear system 4, 5, 6, 7, 8 concerned is locked for only one of the wheels R1, R1′, R2, R2′, R3, R3′ of the working machine. Correspondingly, the sequence shown in FIG. 5 can be scaled as desired and extended to other wheels R1, R1′, R2, R2′, R3, R3′ of the working machine. In particular, the process sequence shown can be extended in such manner that with a plurality of locked differential gear systems 4, 5, 6, 7, 8 a weighting can be applied, to indicate for which of these differential gear systems 4, 5, 6, 7, 8 an unlocking signal should be emitted as a priority. Correspondingly, it is also conceivable that this information should influence the driving dynamics parameters X in relation to the period length of the reversion from the fourth process step D to the first process step A.

INDEXES

[0048] 1 Drive-train [0049] 2 Drive element [0050] 3 Transmission device [0051] 4 Differential gear system [0052] 5 Differential gear system [0053] 6 Differential gear system [0054] 7 Differential gear system [0055] 8 Differential gear system [0056] I, II, III Vehicle axle [0057] R1, R1′ Wheel [0058] R2, R2′ Wheel [0059] R3, R3′ Wheel [0060] S1, S1′ Detection means [0061] S2, S2′ Detection means [0062] S3, S3′ Detection means [0063] A, B, C, D Process step [0064] X Driving dynamics parameter