Method for reversing the direction of travel of a vehicle

Abstract

A method for reversing the direction of travel of a vehicle (8), comprising a drive train with a power-split transmission (1) and a variator (2) for continuously variable transmission, a reversing transmission (3) with a first reversing clutch (3a) for forward travel and a second reversing clutch (3b) for reverse travel, and a control device (4) for reversing the direction of travel from forward travel to reverse travel and vice versa, wherein the reversing of the direction of travel is carried out when this is selected at the control device (4), characterized in that the open of the two reversing clutches (3b, 3a) is pre-filled with a hydraulic fluid in order to shorten the time for reversing the direction of travel according to at least one first filling cycle before the reversing of the direction of travel is selected at the control device (7), wherein the first filling cycle begins withthat a rapid filling pressure (SD) is set for an initial rapid filling time (SZ1), wherein the rapid filling pressure (SD) is reduced to a filling compensation pressure (FD) after the initial rapid filling time (SZ1) has elapsed, which is maintained for a filling compensation time (FZ), wherein the filling compensation pressure (FD) is reduced to a holding pressure (HD) after the filling compensation time (FZ) has elapsed, wherein the first filling cycle ends with the holding pressure (HD) being reduced when a maximum filling cycle time (ZZ) is reached, wherein as soon as the reversing of the direction of travel is selected at the control device (7), the direction of travel is reversed by applying a closing pressure (CD) to the open reversing coupling (3b, 3a) and opening the closed reversing coupling (3a, 3b).

Description

[0001] The invention relates to a method for reversing the direction of travel of a vehicle, comprising a drivetrain with a power-split transmission and a variator for continuously variable transmission, a reversing transmission with a first reversing clutch for forward travel and a second reversing clutch for reverse travel, and a control device for reversing the direction of travel from forward to reverse and vice versa. The drivetrain is designed, in particular, for a work machine. Thus, the vehicle is, for example, designed as a work machine.

[0002] A work machine is a machine that, by its design and its special, permanently attached equipment, is suitable for performing work but not for transporting people or goods. Examples include agricultural machinery, construction machinery, and wheel loaders.

[0003] In a power-split gearbox with reversing clutches, the direction of rotation of the output is changed, i.e., the direction of travel is reversed, by opening the reversing clutch of the current direction of travel and closing the reversing clutch of the new direction of travel.

[0004] Preparing the reversing clutch to close when reversing the direction of travel begins at the earliest when a driver requests a change of direction. The change in the direction of rotation of the power-split transmission must be dynamic and continuous. On the other hand, the reversing clutches must not be overloaded. To ensure this, the reversing clutch to close must be prepared accordingly before it can assume a defined load. Pre-filling the reversing clutch to close requires a certain amount of time. During a normal change of direction from higher speeds, for example, above 15 km / h, pre-filling takes place while the vehicle is decelerating due to the variator pivoting back.In certain driving situations, for example at low speed or when penetrating a pile, the vehicle's deceleration time is shorter than the time required to pre-fill the reversing coupling to be closed, thus delaying the reversal of the direction of travel and reducing the vehicle's productivity.

[0005] The pre-filling of a reversing clutch generally consists of two phases. First, the reversing clutch is pre-filled with oil at a rapid filling pressure for a short period. Then, the pressure is reduced from the rapid filling pressure to a leveling pressure. This leveling pressure ensures that the reversing clutch remains filled and eliminates the play in the clutch plates to such an extent that no torque is transmitted through the clutch when the leveling pressure is applied.

[0006] For example, DE 10 2016 200 174 A1 discloses a reversing method for reversing the direction of travel of a machine with a power-split transmission. A control unit provides control signals, which open a reversing clutch for the current direction of travel and close a reversing clutch for the new direction of travel. The reversing clutches are controlled by actuators. If there is a difference between a reference actuator and a target actuator, the actuator is adjusted, providing an adapted control signal with which the reversing clutches are actuated. In addition to a translational factor and a rotational factor, a load-dependent factor is determined and processed to calculate the target actuators for opening and closing the reversing clutches.

[0007] The object of the present invention is to improve a method for reversing the direction of travel of a vehicle. In particular, a faster reversal of the direction of travel should be achieved, at least in time-critical cases.

[0008] The problem is solved by the subject matter of claim 1. Preferred embodiments are the subject matter of the dependent claims.

[0009] According to the inventive method for reversing the direction of travel of a vehicle, comprising a drive train with a power-split transmission and a variator for continuously variable transmission, a reversing transmission with a first reversing clutch for forward travel and a second reversing clutch for reverse travel, and a control device for reversing the direction of travel from forward travel to reverse travel and vice versa, wherein the reversal of the direction of travel is carried out when this is selected at the control device, wherein the open of the two reversing clutches is pre-filled with a hydraulic fluid in order to shorten the time for reversing the direction of travel according to at least one first filling cycle before the reversal of the direction of travel is selected at the control device, wherein the first filling cycle begins with setting a rapid filling pressure for a first rapid filling time,wherein the rapid filling pressure is reduced to a filling compensation pressure after the first rapid filling time has elapsed, which is maintained for a filling compensation time, wherein the filling compensation pressure is reduced to a holding pressure after the filling compensation time has elapsed, wherein the first filling cycle ends with the holding pressure being reduced when a maximum filling cycle time is reached, wherein as soon as the reversing of the direction of travel is selected at the control device, a reversal of the direction of travel takes place by applying a closing pressure to the open reversing coupling to close it and opening the closed reversing coupling.

[0010] The filling compensation is dimensioned, for example, such that it eliminates any air gap in the reversing coupling to be closed and holds the coupling just before the contact point, so that the coupling is just barely not transmitting any torque. In particular, the coupling is modeled as being subjected to the closing pressure during the closing process, so that at least one gradient or several gradients are established to achieve the closed state.

[0011] A reversing clutch is a switching element that has an open state for disconnecting a rotary connection, a closed state for transmitting torque and rotational speed, and a variety of intermediate states for transmitting specific torque and rotational speed components. The reversing clutch is, for example, designed as a friction clutch. When a reversing request is received from the control unit, the reversing clutch for the current direction of travel opens and the reversing clutch for the new direction of travel closes. Both reversing clutches are located in the reversing gearbox, which is operatively connected to a drive motor on the input side and to a vehicle output on the output side.The term "functionally connected" means that two elements are connected to each other, at least indirectly via other elements such as shafts, gears, or couplings, or directly and thus immediately. In particular, at least one range coupling is arranged in the power flow between the reversing gearbox and the vehicle output.

[0012] The power-split transmission device is, for example, designed as a hydrostatic power-split transmission device, with the variator being a hydrostatic unit. In particular, the power-split transmission device has several driving ranges. These are characterized by different gear ratios. Corresponding to the number of driving ranges of the power-split transmission device, the same number of range clutches must also be provided.

[0013] A first filling cycle refers to the sequence of process steps designed to pre-fill the respective reversing coupling, i.e., to fill it provisionally. This begins with setting the rapid filling pressure for the initial filling time, followed by a reduction to the equalization pressure, which is maintained for the equalization period. Next, it is reduced to the holding pressure, and finally, it is reduced again upon reaching the maximum filling cycle time. Once the reversal of the direction of travel is selected at the control unit, the first filling cycle is completed no earlier than after the equalization period has elapsed. The reversal of the direction of travel is then achieved by applying a closing pressure to the open reversing coupling, which is to be closed to reverse the direction of travel.At the same time, the other, previously closed reversing coupling is opened.

[0014] According to a preferred embodiment of the invention, after completion of the first filling cycle and a waiting period, a second filling cycle is initiated. During this second filling cycle, the rapid filling pressure is set for a second rapid filling time, which is shorter than the first. In particular, the second rapid filling time is shortened by at least 5% and at most 95% compared to the first rapid filling time. This simultaneously reduces the ingress of dirt into the pressure regulator. For example, the waiting time is between 10 and 100 milliseconds.

[0015] For example, it is conceivable to apply holding pressure to the reversing coupling to be closed after the first filling cycle is complete. However, during this time, oil would flow through the pressure regulator of the reversing coupling, which could lead to increased dirt ingress or sludge buildup in the pressure regulator. Therefore, it is advantageous to limit at least the first filling cycle to a maximum time. After this maximum time has elapsed, the reversing coupling to be closed is depressurized, and after a waiting period, a new, second filling cycle is initiated. In particular, shortening the second rapid filling time compared to the first is advantageous because the reversing coupling to be closed will be partially filled after the waiting period and thus not yet completely empty.

[0016] According to a further preferred embodiment of the invention, the second filling cycle is set and executed at least twice consecutively, separated by a waiting period in each case. In other words, at least three filling cycles are executed: the first filling cycle once and the second filling cycle at least twice. After each filling cycle, a waiting period is elapsed before a new filling cycle is executed. As soon as reversing the direction of travel is selected at the control unit, the filling cycle is set at the respective time, but at the earliest after the filling equalization time, by adjusting or modeling the closing pressure provided for closing the pre-filled reversing coupling, and the closed reversing coupling is opened to reverse the direction of travel. If reversing the direction of travel is not selected at the control unit, the process continues as described.Advantageously, after at least three filling cycles, a termination criterion is reached, so that the pre-filling of the reversing coupling to be closed is aborted on suspicion. Only if the control unit detects a further indication of an impending reversal of the direction of travel is the method according to the invention, with the optional further process steps, executed again and terminated either by selecting the reversal of the direction of travel at the control unit or by reaching the termination criterion.

[0017] For example, a suspicion of an imminent reversal of direction arises when the vehicle's speed falls below a certain threshold. Preferably, this threshold is 10 km / h, but more specifically, it is 5 km / h. If the vehicle has decelerated to such a low speed, it can be assumed that a reversal of direction is imminent.

[0018] For example, a suspicion of an imminent reversal of the direction of travel arises when a change in high pressure at the variator exceeds at least a first high-pressure limit. The high pressure at the variator indicates the vehicle's downforce. When a wheel loader plunges into a pile of material, the high pressure at the variator initially increases until a change in the yoke angle reduces the high pressure introduced by the downforce. Therefore, it can be assumed that a reversal of the direction of travel is imminent.

[0019] For example, a suspicion of an impending reversal of the vehicle's direction of travel arises when the position of a bucket exceeds a predefined limit. Consequently, pre-filling of the reversing coupling to be closed is triggered on suspicion when the bucket's position exceeds the designated limit. This limit can specify a position for the bucket, particularly for penetrating a pile of material. Specifically, the limit for the bucket's position relates to its tilt angle.

[0020] For example, a suspicion of an impending reversal of the direction of travel arises if the position of a lifting arm on the vehicle falls below a predefined limit. Consequently, pre-filling of the reversing coupling to be closed is triggered on suspicion if the position of the lifting arm falls below the predefined limit, particularly if the lifting arm is set so low, i.e., so close to the ground, that it is likely to penetrate a pile of material.

[0021] For example, a suspicion of an impending reversal of the direction of travel arises when a sensor device detects objects in the vehicle's vicinity that can no longer be avoided. The sensor device comprises at least one sensor for this purpose. Preferably, the at least one sensor is an optical sensor that receives sensor data regarding the vehicle's surroundings, in particular regarding objects located in the vehicle's direction of travel that would prevent further travel. Thus, pre-filling of the reversing coupling to be closed is triggered on suspicion when objects in the vehicle's vicinity are detected that can no longer be avoided and therefore prevent further travel in the currently set direction.

[0022] For example, a suspicion of an impending reversal of the vehicle's direction of travel arises when a driver releases one of two accelerator pedals below a certain threshold, where one accelerator pedal is for forward travel and the other is for reverse travel. In other words, the vehicle has two accelerator pedals, whereby pressing the first accelerator pedal while simultaneously releasing the second accelerator pedal stops the vehicle from moving forward, and pressing the second accelerator pedal while simultaneously releasing the first accelerator pedal stops the vehicle from moving backward.In other words, the suspicion of an impending reversal of the direction of travel is triggered by the accelerator pedal for the current direction of travel being depressed below a threshold value, for example, for a specific accelerator pedal angle, before the accelerator pedal for the new direction of travel is pressed. This threshold value for the accelerator pedal angle can be, for example, 10%, preferably 5%, of the total accelerator pedal angle.

[0023] Preferably, the driver initiates the reversal of the direction of travel by operating a direction switch or a pedal, whereby a signal to reverse the direction of travel is then transmitted to the control unit. In other words, a request to change the direction of travel or a request to reverse the direction of travel is made via the direction switch or the pedal, whereby corresponding signals are transmitted to the control unit in order to actuate the reversing gear and initiate a reversal of the direction of travel.

[0024] Furthermore, the invention relates to a control unit configured to execute the method according to the invention. The control unit is connected to the vehicle's drivetrain, in particular to the two reversing clutches of the reversing gearbox, for signal transmission. In addition, the control unit can also be connected to sensors, for example, speed or torque sensors, but also pressure sensors, arranged in the drivetrain, or to other control units or control devices, in particular a vehicle control computer and / or an engine control unit.

[0025] An embodiment of the invention is explained in more detail below with reference to the two drawings, wherein identical or similar elements are provided with the same reference numeral. Here, Fig. 1: a simplified schematic representation of a vehicle with a drive train that is controllable according to a method according to the invention, and Fig. 2: a diagram illustrating an exemplary course of a method according to the invention.

[0026] Fig. Figure 1 shows a vehicle designed as a wheel loader 8 with one attached to a lifting frame 10 arranged shovel 9 The vehicle 8 includes a drivetrain that incorporates a power-split transmission 1 and a variator 2 The drivetrain features a continuously variable transmission. Furthermore, it includes a reversing gearbox. 3 with a first reversing coupling 3a for forward travel and a second reversing coupling 3b for reverse driving and a control unit 4for reversing the direction of travel from forward to reverse and vice versa. Therefore, the control device 4 at least for switching the reversing clutches 3a , 3b , especially for filling and emptying the reversing couplings 3a , 3b It is equipped with a hydraulic fluid, in this case oil. Reversing the direction of travel is carried out when this is requested at the control unit. 4 is selected, whereby the selection is made at the control unit 4 by a driver (not shown in detail) via a designated direction switch.

[0027] A drive motor 7 is powered via a drive shaft 14 a drive power into the power-split gearbox 1 , whereby the drive power is transferred via the reversing gearbox 3 into the variator 2 is initiated. Provided that the first reversing coupling 3aWhen closed, drive power is transferred in a first rotational direction into the variator. 2 fed in, whereby a forward movement of the vehicle 8 This occurs when the second reversing coupling... 3b When closed, drive power is transferred in a second rotational direction into the variator. 2 fed in, during a reverse movement of the vehicle 8 This is done. Because the variator 2 It adjusts the gear ratio continuously and transmits the drive power via a range coupling. 5 at a respective drive 6 , which has the power-split transmission 1 is effectively connected. In the present case, the vehicle exhibits 8 two drive axles, each with its own output 6 represent. On the vehicle's drive axles 8 are drive wheels 13 arranged for the vehicle drive.

[0028] The control unit 4is via a first line 15 signal transmission with the power-split gearbox 1 , especially with those in the reversing gear 3 arranged reversing couplings 3a , 3b The control unit is connected via signal transmission. 4 via a second line 16 with a sensor device 11 of the vehicle 8 connected. The sensor device 11 It includes several sensors that are used to detect the vehicle's surroundings. 8 , especially of objects 12 in the direction of travel of the vehicle 8 are planned. The object in question is a pile-like structure. 12 in front of the vehicle in the direction of travel 8 arranged, wherein the lifting frame 10 lowered and the shovel 9 is set for piercing the pile. The control unit 4It can also be connected to other components of the vehicle, especially the powertrain, via signal transmission.

[0029] According to Fig. 2. Two diagrams are combined into a common diagram to illustrate the inventive method for reversing the direction of travel of the in Fig. 1 of the depicted vehicle 8 to illustrate. On each abscissa X The two diagrams represent a time T In contrast, on each ordinate... Y - from bottom to top - first a pressure curve DW at the second reversing coupling 3b and above each position of the direction switch is plotted. Up to a twelfth point in time. T12 The direction switch is moved to the first forward position. VF set up, whereby after the twelfth point in time T12 the second position of the direction switch for reverse RF is being discontinued.

[0030] Known systems and methods from the prior art begin filling the reversing coupling to initiate a change of direction as soon as the direction switch is moved from the first to the second position. This results in the reversing coupling being pre-filled, i.e., a rapid filling pressure is set for a specific filling time, followed by a compensating filling pressure for a specific compensating time, before the coupling can be subjected to the closing pressure. This pre-filling is necessary to prevent overloading the reversing coupling and to initiate a defined load transfer from one coupling to the other. In time-critical situations, such as when a wheel loader bucket is penetrating a pile of material, there is a need to achieve a faster reversal of the direction of travel to increase vehicle productivity.

[0031] According to the inventive method, the time required to reverse the direction of travel is reduced by opening the reversing coupling, in this case the second reversing coupling, according to at least one first filling cycle. 3b , is pre-filled with a hydraulic fluid on suspicion before reversing the direction of travel at the control unit 7 is selected.

[0032] In the present case, at a first point in time, T1 a suspicion of an imminent reversal of the direction of travel, because of the vehicle's speed 8 has fallen below a speed limit. In other words, the vehicle's speed is 8 so slight that there is reason to suspect an imminent reversal of the direction of travel. Furthermore, this suspicion is confirmed by the position of the shovel. 9 of the vehicle8 a specified limit value was exceeded and the position of the lifting frame was affected. 10 of the vehicle 8 has fallen below a prescribed limit value. According to Fig. The lifting frame is located at point 1. 10 in a lower position, with the shovel 9 in a position intended for piercing the pile, for example when the shovel 9 The angle of incidence is tilted in such a way that a specified limit value is exceeded. Furthermore, the suspicion of an impending reversal of the direction of travel can be confirmed by a change in high pressure at the variator. 4 at least one initial high-pressure limit is exceeded. This occurs, for example, when the shovel 9 by penetrating the pile to slow down the vehicle 8 leads.

[0033] Furthermore, the suspicion of an imminent reversal of the direction of travel is also confirmed by the fact that the sensor device 11 the pile as an object 12 in the vicinity of the vehicle 8 detected that is no longer avoidable, so a further reduction in speed and a subsequent reversal of the direction of travel are likely.

[0034] The first filling cycle begins with the first time T1 a quick-fill print SD for an initial quick-fill time SZ1 is set. The quick-fill pressure SD after the first quick-fill period has elapsed SZ1 at a second point in time T2 lowered, with a third point in time T3 a filling equalization pressure FD is set for a filling compensation time FZ is held. After the filling equalization time has elapsed FZ at a fourth point in time T4The filling equalization pressure will be FD lowered and at a fifth point in time T5 A holding pressure will be applied. HD adjusted. By lowering the filling pressure. FD on the holding pressure HD is ensured that the second reversing coupling to be closed 3b It certainly does not transmit any torque in its pre-filled state. To ensure this, the filling equalization pressure is... FD by at least 5% on the holding pressure HD lowered. The first filling cycle ends at a sixth point in time. T6 so that a maximum filling cycle time ZZ is achieved and the holding pressure HD upon reaching the maximum filling cycle time ZZ is lowered. In particular, the second reversing coupling to be closed is lowered. 3b no longer exposed to the hydraulic fluid, so that from the sixth point onwards T6 It is pressure-free. If during the filling cycle time ZZ Since no request for a change of direction has been made, the pre-filling process is aborted and the second reversing coupling is engaged. 3b for a configurable waiting time WZ Leave without pressure.

[0035] After the waiting period has expired WZ A second filling cycle is initiated, with the second filling cycle occurring at the seventh time. T7 the quick-fill pressure SD for a second quick-fill time SZ2 up to an eighth point in time T8 is set. The second quick-fill time SZ2 compared to the first quick fill time SZ1 shortened.

[0036] The quick-fill pressure SD after the second quick-fill time has elapsed SZ2 at the eighth time T8 lowered, with a ninth point in time T9 the filling equalization pressure FD is set, which is used for the filling compensation time FZ is held. After the filling equalization time has elapsed FZ at a tenth point in time T10 The filling equalization pressure will be FD lowered and at an eleventh point in time T11 A holding pressure will be applied. HD The second filling cycle ends at a twelfth point in time. T12 so that the direction of travel is controlled by the steering device 7 is reversed. In other words, at the twelfth point... T12 the direction switch from the first position forward VF to the second position, reverse driving RF switched. When reversing the direction of travel, the second reversing coupling to be closed is engaged. 3b with a closing pressure CD actuated and the closed first reversing coupling 3a The valve, which previously enabled forward movement, is opened and thus depressurized. The closing pressure is then adjusted. CD This is achieved by setting an initial pressure gradient between the twelfth point in time. T12 and the thirteenth point in time T13 as well as by subsequently setting a second pressure gradient between the thirteenth time T13 and the fourteenth point in time T14 The second pressure gradient is greater than the first pressure gradient. Alternatively, it is also conceivable to set a continuous, for example quadratic, exponential, or other curve for closing. Setting a pressure gradient that is necessary for closing the reversing coupling to be closed 3b The setup includes a modeled closing or a modeled actuation of the reversing coupling to be closed. 3b with the closing pressure CD to understand. Because of the second reversing coupling 3bBecause the vehicle is already pre-filled with hydraulic fluid due to the suspicion of an imminent reversal of the direction of travel, the reversal of the direction of travel occurs more quickly, so that the vehicle 8 For example, it can change direction immediately after penetrating the pile. This rapid reaction capability significantly increases the vehicle's ease of operation and productivity. 8 . Reference symbol list 1 power-split gearbox 2 Variator 3 reversing gears 3a first reversing coupling 3b second reversing coupling 4 Control unit 5 range coupling 6 Drive 7 Drive machine 8 vehicles 9 shovels 10 lifting frames 11 Sensor device 12 objects 13 Drive wheel 14 Drive shaft 15 Management 16 Management VF Forward travel RF Reverse SD Quick Fill Pressure SZ1 first rapid filling time SZ2 second quick fill time FD filling equalization pressure FZ Filling Equalization Time HD holding pressure CD closing pressure WZ waiting time ZZ Filling cycle time T time T1 first time point T2 second time point T3 third point in time T4 fourth point in time T5 fifth point in time T6 sixth point in time T7 seventh point in time T8 eighth time point T9 ninth point in time T10 tenth point in time T11 eleventh point in time T12 twelfth point in time T13 thirteenth point in time T14 fourteenth point in time X Abscissa Y Ordinate QUOTES INCLUDED IN THE DESCRIPTION

[0000] This list of documents cited by the applicant was automatically generated and is included solely for the reader's convenience. The list is not part of the German patent or utility model application. The DPMA accepts no liability for any errors or omissions. Cited patent literature

[0000] DE 102016200174 A1

[0006]

Claims

[1] Method for reversing the direction of travel of a vehicle (8) comprising a drive train with a power-split transmission (1) and a variator (2) for continuously variable transmission, a reversing transmission (3) with a first reversing clutch (3a) for forward travel and a second reversing clutch (3b) for reverse travel, and a control device (4) for reversing the direction of travel from forward travel to reverse travel and vice versa, wherein the reversing of the direction of travel is carried out when this is selected at the control device (4), characterized by, that the open of the two reversing couplings (3b, 3a) is pre-filled with a hydraulic fluid in order to shorten the time for reversing the direction of travel according to at least one first filling cycle before the reversal of the direction of travel is selected at the control device (7), wherein the first filling cycle begins by setting a rapid filling pressure (SD) for a first rapid filling time (SZ1), wherein the rapid filling pressure (SD) is reduced to a filling compensation pressure (FD) after the first rapid filling time (SZ1) has elapsed, which is held for a filling compensation time (FZ), wherein the filling compensation pressure (FD) is reduced to a holding pressure (HD) after the filling compensation time (FZ) has elapsed, wherein the first filling cycle ends by reducing the holding pressure (HD) when a maximum filling cycle time (ZZ) has been reached, wherein as soon as the reversal of the direction of travel is selected at the control device (7),The direction of travel is reversed by applying a closing pressure (CD) to the open reversing coupling (3b, 3a) and opening the closed reversing coupling (3a, 3b). [2] Method according to claim 1, characterized by , that after completion of the first filling cycle and expiry of a waiting period (WZ) a second filling cycle is initiated, whereby according to the second filling cycle the rapid filling pressure (SD) is set for a second rapid filling time (SZ2), whereby the second rapid filling time (SZ2) is shortened compared to the first rapid filling time (SZ1). [3] Method according to claim 2, characterized by that the second filling cycle is set at least twice in succession, separated by a respective waiting time (WZ). [4] Method according to any one of the preceding claims, characterized by, that there is a suspicion of an imminent reversal of the direction of travel if the speed of the vehicle (8) falls below a speed limit. [5] Method according to any one of the preceding claims, characterized by , that there is a suspicion of an imminent reversal of the direction of travel if a change in a high pressure at the variator (4) exceeds at least a first high pressure limit. [6] Method according to any one of the preceding claims, characterized by , that there is a suspicion of an imminent reversal of the direction of travel if a position of a bucket (9) of the vehicle (8) exceeds a limit value provided for this purpose. [7] Method according to any of the preceding claims, characterized by , that there is a suspicion of an imminent reversal of the direction of travel if a position of a lifting frame (10) of the vehicle (8) falls below a limit value provided for this purpose. [8] Method according to any one of the preceding claims, characterized by , that there is a suspicion of an imminent reversal of the direction of travel if a sensor device (11) detects objects (12) in the vicinity of the vehicle (8) that can no longer be avoided. [9] Method according to any one of the preceding claims, characterized by , that a driver initiates the reversal of the direction of travel by operating a direction switch or a pedal, whereby a signal to reverse the direction of travel is then transmitted to the control unit (4). [10] Method according to any one of claims 1 to 8, characterized by , that there is a suspicion of an imminent reversal of the direction of travel if a driver releases one of two accelerator pedals below a threshold, where a first accelerator pedal is for forward travel and a second accelerator pedal is for reverse travel. [11] Control device (4) which is configured to perform a method according to any one of claims 1 to 10.

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