Method for controlling a driving dynamics function of a work machine

Abstract

A method for controlling driving dynamic functions of a working machine having at least two axles, wherein the current wheel speed of at least one wheel is detected and the speed is supplied to a control device for comparison with the permissible wheel speed of the same wheel and the wheel slip is calculated therefrom, wherein if the wheel slip has an impermissible value, a control signal for locking at least one differential is output by the control device, wherein a control signal for unlocking is periodically output for the relevant differential and a new comparison of the wheel speeds is performed, wherein if the wheel slip still has an impermissible value, a control signal for locking the relevant differential is output again, characterized in that a path distance is detected by means of a detection device and the value of the wheel slip of at least one wheel has an impermissible value along the path distance.

Description

Technical Field

[0001] The invention relates to a method for controlling a driving dynamics function of a work machine. A work machine describes a vehicle having devices for performing work, wherein these devices can be fixedly or detachably connected to the work machine. In particular, a work machine is to be understood as an agricultural machine and / or a construction machine. In particular, but not exclusively, the work machine can be a multi-axle dump truck, for example a so-called dump truck. Technical Background

[0002] The work machine may have a driven front axle and a driven rear axle, each having a transverse differential for speed compensation between the two wheels of the axle. A longitudinal differential for speed compensation between the two axles may be arranged between the front axle and the rear axle. Each wheel of the work machine may have a speed sensor, by means of which it is determined whether the wheel is slipping. In the event of slippage of at least one wheel, it may be necessary to lock one or more differentials.

[0003] For example, from EP 2949507 A1 a vehicle and a method for controlling a vehicle are known, wherein the vehicle has an unloading mechanism. In addition, the vehicle has a control system designed to actuate the brake device and lock the interaxle differential when the control system detects a request to unload material and the transmission is in neutral. Summary of the invention

[0004] The invention is based on the object of providing an improved method for controlling a driving dynamics function of a work machine. The invention also relates to a work machine having a control device which implements the method according to the invention. The invention also relates to a computer program product for executing the method.

[0005] According to the invention, this object is achieved by means of a method for controlling a driving dynamics function of a work machine having at least two axles, a work machine and a computer program product.

[0006] In the method according to the invention for controlling driving dynamic functions of a working machine having at least two axles, the current wheel speed of at least one wheel is detected and supplied to a control device for comparison with the permissible wheel speed of the same wheel and for calculating the wheel slip therefrom, wherein if the wheel slip has an impermissible value, a control signal for locking at least one differential is output by the control device, wherein a control signal for unlocking is periodically output for the relevant differential and a new comparison of the wheel speeds is performed, wherein if the wheel slip still has an impermissible value, a control signal for locking the relevant differential is output again, wherein the value of the wheel slip of the at least one wheel is detected along a path along which it has an impermissible value by means of a detection device.

[0007] The working machine according to the present invention comprises:

[0008] a drive train having a drive element, at least one lockable differential, at least two axles and at least one wheel mounted on each axle;

[0009] -Detection device;

[0010] A control device which is designed to carry out the method according to the invention.

[0011] The computer program product according to the invention has a program code for carrying out the method according to the invention when the program code is executed on a computer.

[0012] Accordingly, the method is provided for controlling driving dynamic functions of a working machine having at least two axles. In particular, the two axles are respectively a front axle and a rear axle. However, a vehicle arrangement with more than two axles, in particular a front axle and two or more rear axles, is also conceivable. The wheels are arranged on the axles. According to the method, the current wheel speed of at least one wheel is detected and supplied to a control device for comparison with the permissible wheel speed of the same wheel. The wheel slip is calculated from the current wheel speed and the permissible wheel speed for the respective driving situation.

[0013] When the wheel slip has an inadmissible value, the control device outputs a signal for locking at least one differential gear. For the relevant locked differential, a control signal for unlocking is periodically output and a new comparison of the wheel speeds is performed. As long as the wheel slip of the relevant wheel still has an inadmissible value, a control signal for locking the relevant differential is output again.

[0014] In the above-mentioned relationship, the current wheel speed is understood to be the actual existing wheel speed of the relevant wheel. The control device can be an electrical control device. By way of example but not exclusively, the control device can be a vehicle control device (e.g., a vehicle control computer), an engine control device, a transmission control device, a control device for driving dynamics functions, or another suitable control device.

[0015] The permissible wheel speed of a wheel describes the speed that is expected based on other driving dynamics parameters of the working machine. In particular, the wheel speed is understood to be the wheel speed that should be present at the relevant wheel in an ideal situation, at the current engine speed, taking into account the different transmission ratios of the transmission and under ideal conditions (e.g., without slip). The corresponding driving situation, in particular driving through a bend or existing steering movements, also has an influence on the wheel speed. With respect to the permissible wheel speed, tolerances for exceeding / falling below the permissible wheel speed can also be set. Accordingly, an impermissible value of the wheel speed is understood to be a value that is either different from the permissible wheel speed or is outside the relevant tolerance range.

[0016] In this context, a differential describes a compensating transmission which can compensate for different rotational speeds between two shafts, in particular. A distinction is made here between so-called transverse differentials and longitudinal differentials. A transverse differential enables rotational speed compensation between the wheels of an axle, in particular when negotiating a bend. In contrast, a longitudinal differential can be used to achieve rotational speed compensation between different axles. With regard to the differential, locking the differential is understood to mean reducing or completely locking the aforementioned compensating movement or rotational speed compensation. Thus, in a completely locked differential, both shafts rotate at the same speed. Similarly, unlocking the differential is understood to mean either at least partially opening a completely locked differential or completely opening it, thereby partially or completely achieving a compensating movement or rotational speed compensation.

[0017] Periodically outputting a control signal that unlocks a locked differential is understood to mean repeatedly, in particular, outputting the same control signal at the same time interval. Here, the corresponding cycle length can depend on different influencing factors and can therefore also be changed.

[0018] According to the invention, a detection device is used to detect a path along which the value of the wheel slip of the at least one wheel has an inadmissible value. The detection device can be, for example, a rotation speed sensor of the wheel (on the wheel or on the corresponding bridge), which has an admissible wheel speed or an admissible wheel slip. In addition, the detection device can be at least one GPS sensor, which receives a position signal and transmits it to the control device. Alternatively or in addition, the detection device can also be one or more acceleration sensors, distance sensors or laser sensors. In particular, the detection device can also be designed in the form of an optical sensor for detecting the speed, which is advantageously directed to the path or the ground below the working machine. Accordingly, the path is the length of the travel path or the route passed. Therefore, according to the invention, a path is detected, which, due to its characteristics, leads to an inadmissible value of the wheel slip. In particular, an inadmissible value of the wheel slip can be caused by a reduction in traction that may be caused by the characteristics of the path. Therefore, environmental influences can reduce the traction of the path in particular. In this regard, reference is made to different types of land / ground, snow, ice, precipitation (in particular the resulting mud formation).

[0019] In an advantageous development of the method according to the invention, in addition to the path, the position is also determined, wherein a control signal for locking is output in anticipation for at least one further differential before the further wheels have travelled over the respective path.

[0020] GPS data can be used here to determine the position. Alternatively, information about the axle spacing can also be used in order to determine, for example, when the wheels of the second axle have passed through an area with reduced traction when an impermissible wheel slip of the wheels of the first axle has been detected. The at least one further differential can in particular be a transverse differential of the second and / or third axle. Alternatively, the at least one further differential can also be understood as a longitudinal differential. In this context, the expression predictability is therefore understood to mean that the locking of the further differential gear is initiated prospectively, i.e. before a possible loss of traction actually occurs. This can further improve the driving dynamics of the work machine.

[0021] In addition, advantageously, a control signal for unlocking is periodically output for the at least one other differential, and the wheel speed comparison is performed again. If the wheel slip of the relevant wheel or the wheel speed still has an impermissible value, a control signal for locking the relevant differential is output again.

[0022] According to an advantageous extension of the method of the invention, the closing time of at least one locked differential is adjusted to a value resulting from the cycle length, taking into account other driving dynamic parameters. The driving dynamic parameters mentioned can in particular be information about the driving of the working machine on a bend. For better handling sensitivity, it may therefore be necessary to at least partially unlock the locked differential when turning. In addition, information representing cumulative paths with reduced traction or impermissible wheel slip values ​​can also be transmitted. Accordingly, if (consecutive) paths with reduced traction are identified over a longer period of time or other cycles, the closing time or the corresponding cycle length can be increased for the purpose of reducing wear. In contrast, if only very short paths with reduced traction or impermissible wheel slip are identified, the cycle length can be shortened.

[0023] Advantageously, if it can be expected with high probability that the wheel slip is at a permissible value when unlocking this differential, a control signal for unlocking is first output for such a differential and the wheel slip is determined again. If the wheel slip also still has an impermissible value here, a control signal for locking the relevant differential is output again. In other words, a prioritization or weighting can be performed for which wheel is likely to drive through an area with high traction next. For this purpose, information about the length of the path or the position of the respective path with low and high traction is particularly useful.

[0024] As long as the wheel slip still has an impermissible value in the previously unlocked differential, the periodic output of the control signal for unlocking the remaining differential is advantageously interrupted. In other words, the period length of the output of the control signal for unlocking the remaining differential is increased.

[0025] Advantageously, the detection means uses the wheel speed of at least one other wheel. Ideally, this is a permissible value for the wheel speed. In addition, however, wheel speed values ​​of a plurality of wheels can also be used. Thus, the wheel speed values ​​of different wheels can also be checked for plausibility.

[0026] In a further advantageous embodiment of the method according to the invention, the detection means uses the signal for determining the position data.

[0027] According to a further aspect of the invention, the invention comprises a working machine having a drive train with a drive element, at least one lockable differential, at least two axles and at least one wheel arranged on each axle. In addition, the working machine comprises a detection device and a control device as described in the above manner, which is designed to implement the method according to the invention. Ideally, each axle is assigned two wheels, one wheel on the left side of the vehicle and one wheel on the right side of the vehicle. Arrangements with so-called dual tires or dual axles are also conceivable.

[0028] Furthermore, the present invention includes a computer program product with a program code for implementing the method when the program code is executed on a computer. The computer can be, for example, a control device. Alternatively, it is also conceivable that the computer is arranged in a distributed manner on the working machine. In particular, it should be understood that the control device of the working machine and the computer interact and exchange data, for example, via a wireless connection. Accordingly, signal information for locking or unlocking can be sent by the computer to the control device of the working machine. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] The present invention will be described in detail with reference to the following drawings. In the drawings:

[0030] Figure 1 : shows a schematic diagram of a first power transmission system of a working machine;

[0031] Figure 2 : shows a schematic diagram of a second power transmission system of the working machine;

[0032] Figure 3 : shows a schematic diagram of a third power transmission system of the working machine;

[0033] Figure 4 : shows a schematic diagram of a fourth power transmission system of the working machine;

[0034] Figure 5 : shows a simplified flow chart of the method according to the present invention. DETAILED DESCRIPTION

[0035] Figure 1A drive train 1 of a working machine is shown in a highly simplified schematic diagram. The drive train 1 has a first axle, a second axle and a third axle I, II, III, wherein the first axle I is implemented as a front axle and the second axle and the third axle II, III are implemented as rear axles. The first axle I is assigned two wheels R1, R1', the second axle II is assigned two wheels R2, R2', and the third axle III is assigned two wheels R3, R3'. In addition, the first axle I is assigned two detection devices S1, S1', the second axle II is assigned two detection devices S2, S2', and the third axle III is assigned two detection devices S3, S3'. The detection devices S1, S1', S2, S2', S3, S3' are rotational speed sensors.

[0036] The first axle I also has a differential 4, the second axle II has a differential 6, and the third axle III has a differential 7. The differentials 4, 6, 7 are designed as transverse differentials. They can therefore achieve rotational speed compensation between the wheels R1, R1', R2, R2', R3, R3' of the respective axles I, II, III.

[0037] Furthermore, a differential 5 is arranged between the first and second axles I, II, and a differential 8 is arranged between the second and third axles II, III. The two differentials 5, 8 are designed as longitudinal differentials and enable rotational speed compensation between the first and second axles I, II or between the second and third axles II, III.

[0038] The drive element 2 provides the necessary drive power. The drive element 2 can be implemented as a combustion power machine in particular. However, it is also conceivable that the drive element is an electric motor here. The transmission device 3 is shown by means of a dotted line. Here, the transmission device is in particular a drive shaft, which is arranged between the corresponding differentials 4, 5, 6, 7, 8 or between the differential 5 and the drive element 2. The speed or torque is transmitted by the transmission device 3. As long as the working machine or its power train 1 moves in the forward driving direction F, the wheels R1, R1' of the first axle I pass through the path, while the wheels R2, R2' of the second axle II pass through the same section at a time offset. In the same way, the wheels R3, R3' of the third axle III pass through the section at a time offset. Now, if an unallowable wheel speed of one of the wheels R1, R1' is detected by one of the detection devices S1, S1' of the first axle I, a signal for locking the differential 4 is output by a control device not shown here. If an inadmissible value of the wheel speed is detected for one of the wheels R2, R2' of the second axle II or one of the wheels R3, R3' of the third axle III, the same procedure is followed. Accordingly, the differential 6 and / or the differential 7 is locked, or a signal for locking the differential 6, 7 is output.

[0039] As soon as inadmissible values ​​of the wheel speed are detected simultaneously for both wheels R1 , R1 ′, R2 , R2 ′, R3 , R3 ′ of an axle I, II, III, a signal for locking the differential 5 and / or the differential 8 is output, and the differentials 5 , 8 are locked.

[0040] Since the distance between the axles I, II, III is not changeable, it is possible to infer a loss of traction in the event of an impermissible wheel speed on one of the axles I, II, III and calculate when one of the following axles II, III has just passed this area. Accordingly, a signal for locking the differential 6 or 7 can be given as soon as it is reached or slightly in advance.

[0041] Also not shown are further detection means, which are designed, for example, as GPS sensors. These further detection means can be provided in addition to the existing detection means S1 , S1 ′, S2 , S2 ′, S3 , S3 ′.

[0042] In the embodiment of the drive train 1 shown here, the differentials 4, 5, 6, 7, 8 are arranged centrally. This means that they are at the same distance from the left and right vehicle sides of the work machine. In addition, the second axle II is designed as a so-called through-axle. This means that the differential 6 ensures transmission to the differential 8 in addition to speed compensation on the second axle II, or thus also to the third axle III.

[0043] Figure 2 The second power transmission system 1 is shown schematically. Figure 1 The drive train 1 described in the embodiment of the present invention differs in that the differentials 4, 5, 6, 7, 8 are no longer arranged centrally. Instead, the differentials 4, 6, 7 are arranged parallel and offset relative to the differentials 5, 8 at the same intervals with respect to the driving direction F. In addition, the differential 5 is now connected to the differential 8 via the transmission device 3, and the differential 8 is connected to the differential 6 and the differential 7 via the transmission device 3. As a result, the second axle II is no longer implemented as a through-drive axle. However, the method according to the invention can be implemented in the same way with the current drive train 1.

[0044] Figure 3 An alternative embodiment is shown schematically and thus a third drive train 1 is shown. Figure 1 The embodiment described in FIG. 1 differs in that the differential 8 between the second and third axles II, III is omitted. All other elements of the drive train 1 and their functional connections are identical to those in FIG. Figure 1 The arrangement and operation are consistent with those described in .

[0045] exist Figure 4 The schematic diagram shows the Figure 2 A modification of the powertrain 1 shown in FIG. Figure 2 In contrast to the embodiment shown in FIG. 1 , the drive train 1 shown here has a direct connection between the differential 6 and the differential 5 or also between the differential 7 and the differential 5 by means of the transmission device 3. Figure 2 and Figure 4 The embodiments shown in FIG. 8 correspond in all other features.

[0046] It should generally be noted that the wheels R1 , R2 , R3 are each arranged on the left vehicle side of the work machine, and the wheels R1 ′, R2 ′, R3 ′ are each arranged on the right vehicle side of the work machine.

[0047] Figure 5The method according to the invention is shown in a highly simplified form with the aid of a flow chart. In this case, in a first step A, a signal is output for unlocking the respective differential 4, 5, 6, 7, 8. This signal can be output independently of the preceding program or method sequence in order to ensure that all differentials 4, 5, 6, 7, 8 are in an unlocked or open state. Advantageously, the first method step A can also be performed when the vehicle is restarted. Alternatively, it is also conceivable that the first method step A is omitted when the vehicle is restarted and that all differentials 4, 5, 6, 7, 8 are in their last set actuation state.

[0048] In a second method step B, the rotational speed of at least one wheel R1, R1', R2, R2', R3, R3' is detected. This is done in particular by means of detection means S1, S1', S2, S2', S3, S3'.

[0049] Subsequently, in a third step C, a comparison of the detected rotational speed with the permissible rotational speed is carried out. As soon as the detected rotational speed corresponds to the permissible rotational speed or corresponds to the permissible rotational speed taking into account the tolerance range, a feedback is provided from the third method step C to the second method step B. In particular, it is intended that the corresponding wheel rotational speeds are detected again periodically and the comparison is performed. In this case, the time interval for the repeated detection and comparison of the wheel rotational speeds, i.e. the cycle length, can have a fixed value or can be varied as a function of other parameters.

[0050] As soon as it is determined in the third method step C that the detected speed has or has reached an impermissible speed value, a signal for locking the relevant differential 4, 5, 6, 7, 8 is generated in a fourth method step D and output by a control device (not shown here). In addition, a feedback is provided from the fourth method step D to the first method step A. The feedback between the fourth method step and the first method steps D, A ensures that the relevant differential 4, 5, 6, 7, 8 remains in the locked state only for the time required for optimal driving operation.

[0051] This feedback is also carried out periodically. This also means that the relevant differential 4, 5, 6, 7, 8 is kept in the locked state produced by the fourth method step D for a certain period of time before the signal for unlocking the corresponding differential 4, 5, 6, 7, 8 is output by the first method step A. The cycle length after which the switch from the fourth method step D to the first method step A is made can be influenced by the driving dynamics parameter X. Therefore, such a driving dynamics parameter X can especially help to shorten the set cycle length. This is especially provided when the working machine starts to travel around a bend or reaches or exceeds the limit value of the turning radius, wherein the locked differential 4, 5, 6, 7, 8 has an adverse effect on the driving dynamics of the working machine.

[0052] According to the method of the present invention, Figure 5 The process described in reflects the detection of the wheel speed and, in the event of an impermissible wheel speed, the unlocking of the associated differential 4, 5, 6, 7, 8 for only one wheel R1, R1', R2, R2', R3, R3' of the work machine. Figure 5 The process shown in can be expanded or reduced as desired and can be extended to other wheels R1, R1', R2, R2', R3, R3' of the working machine. The method process shown can be extended in particular by weighting the multiple locked differentials 4, 5, 6, 7, 8 for which of the differentials 4, 5, 6, 7, 8 the signal for unlocking should be output first. Accordingly, it is also conceivable to influence the driving dynamics parameter X in terms of the cycle length fed back from the fourth method step D to the first method step A.

[0053] List of Reference Numerals

[0054] 1 Powertrain

[0055] 2 Drive components

[0056] 3 Transmission equipment

[0057] 4 Differential

[0058] 5 Differential

[0059] 6 Differential

[0060] 7 Differential

[0061] 8 Differential

[0062] I, II, III axles

[0063] R1, R1' wheels

[0064] R2, R2' wheels

[0065] R3, R3' wheels

[0066] S1, S1' detection device

[0067] S2, S2' detection device

[0068] S3, S3' detection device

[0069] A, B, C, D method steps

[0070] X Driving dynamics parameters

Claims

1. A method for controlling driving dynamics functions of a working machine having at least two axles (I, II, III), wherein: The present wheel speed of at least one wheel (R1, R1', R2, R2', R3, R3') is detected and transmitted to a control device for comparison with the permitted wheel speed of the same wheel (R1, R1', R2, R2', R3, R3'), and wheel slip is calculated therefrom, wherein if the wheel slip has an impermissible value, a control signal for locking at least one differential (4, 5, 6, 7, 8) is outputted by the control device, wherein a control signal for unlocking is periodically outputted for the relevant differential (4, 5, 6, 7, 8), and a new comparison of the wheel speeds is performed, wherein if the wheel slip also has an impermissible value, a control signal for unlocking is outputted periodically for the relevant differential (4, 5, 6, 7, 8), and a new comparison of the wheel speeds is performed. If the wheel slip value of at least one wheel (R1, R1', R2, R2', R3, R3') has an impermissible value, a control signal for locking the relevant differential (4, 5, 6, 7, 8) is output again, wherein the value of the wheel slip of at least one wheel (R1, R1', R2, R2', R3, R3') is detected by means of a detection device (S1, S1', S2, S2', S3, S3') along the path having the impermissible value, wherein in addition to the path, its position is also determined, wherein a control signal for locking the corresponding differential (4, 5, 6, 7, 8) is output in anticipation for at least one other differential (4, 5, 6, 7, 8) before the other wheel (R1, R1', R2, R2', R3, R3') passes the path.

2. The method according to claim 1, characterized in that A control signal for unlocking the at least one other differential (4, 5, 6, 7, 8) is periodically output and the wheel speeds are compared again, wherein if the wheel slip still has an impermissible value, a control signal for locking the relevant differential (4, 5, 6, 7, 8) is output again.

3. The method according to claim 2, characterized in that A value resulting from the cycle length of the closing time of the at least one locked differential (4, 5, 6, 7, 8) is adjusted taking into account a further driving dynamics parameter (X).

4. The method according to any one of claims 1 to 3, characterized in that In the case of a high probability expectation that the wheel slip is at a permissible value when unlocking the differential, a control signal for unlocking is first output for such a differential (4, 5, 6, 7, 8) and a determination of the wheel slip is performed, wherein, if the wheel slip still has an impermissible value, a control signal for unlocking the relevant differential (4, 5, 6, 7, 8) is again output.

5. The method according to claim 4, characterized in that If an impermissible value has previously been determined for the wheel slip, the periodic output of the control signals for unlocking the remaining differentials (4, 5, 6, 7, 8) is interrupted.

6. The method according to any one of claims 1 to 3, characterized in that The detection means (S1, S1', S2, S2', S3, S3') use the wheel speed of at least one other wheel (R1, R1', R2, R2', R3, R3').

7. The method according to any one of claims 1 to 3, characterized in that The detection means (S1, S1', S2, S2', S3, S3') use the signals for determining position data.

8. A working machine having: - a drive train (1) comprising a drive element (2), at least one lockable differential (4, 5, 6, 7, 8), at least two axles (I, II, III) and at least one wheel (R1, R1', R2, R2', R3, R3') arranged on each axle (I, II, III); - detection devices (S1, S1', S2, S2', S3, S3'); A control device designed to carry out the method according to any one of claims 1 to 7. 9 . A computer program product having a program code for carrying out the method according to claim 1 , when the program code is executed on a computer.

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