METHOD AND DEVICE FOR STABILISING A TRACTION VEHICLE-TRAILER COMBINATION, AND CONTROL UNIT

Abstract

A method is proposed for stabilizing a tractor-trailer combination comprising a tractor vehicle and a trailer. The tractor vehicle has front and rear axle steering. The distinguishing feature of the method is that while driving, and braking while rounding a curved trajectory, the steering angle of the wheels on the rear axle is set to be in the same direction as the steering angle of the wheels on the front axle in order to stabilize the tractor-trailer combination.

Claims

1-11. (canceled)

12. A method for stabilizing a tractor-trailer combination (30) comprising a tractor vehicle (1) and a trailer (20), wherein the tractor vehicle (1) has a steerable axle and a steerable rear axle, and the method comprising: when braking the tractor-trailer combination (30) while driving round a curved trajectory, setting a steering angle for wheels (4, 5) of the rear axle at a same direction as a steering angle of wheels (2, 3) of the front axle in order to stabilize the tractor-trailer combination (30).

13. The method according to claim 12, further comprising, during the operation of the tractor-trailer combination, monitoring a yaw torque (M.sub.Gier) of the tractor vehicle (1), at least at intervals, in order to produce the steering angle in the same direction at the rear axle in the event of instability of the tractor-trailer combination (30).

14. The method according to claim 12, further comprising determining the braked curved trajectory by at least one of: acceleration sensors present in the tractor vehicle (1), and/or recognizing a braking process at least at one wheel of the tractor vehicle (1) and/or the trailer (20).

15. The method according to claim 12, further comprising, during the braked curved trajectory, increasing the wheel steering angle (α) at the front axle, as a function of the speed at the time, in order to reduce a turning radius.

16. The method according to claim 12, further comprising using the method with the tractor-trailer combination (30) when driving downhill, even while driving unbraked round a curved trajectory.

17. The method according to claim 12, further comprising, when a parking process is recognized, interrupting the method until completion of the parking process so that steering angles, in opposite directions at the front and rear axles, are permitted in order to provide maximum maneuverability during the parking process.

18. A control unit for a tractor vehicle (1) for carrying out the method according to claim 12, such that the method can be carried out using the control unit for stabilization.

19. The control unit according to claim 18, wherein the method is carried out at least in part using a control unit already present in the vehicle.

20. The control unit according to claim 19, wherein the control unit already present in the vehicle is an ESP control unit.

21. The control unit according to claim 18, wherein the method is carried out, at least in part, using an ESP control unit already present in the vehicle, wherein the ESP control unit is connected at least to sensors, by way of a vehicle bus system, in order to evaluate: the wheel steering angle of the wheels of the tractor vehicle (1), and/or a speed of the tractor vehicle (1), and/or a behavior of the trailer, and/or a yaw torque of the tractor vehicle (1), and/or a braking process at the tractor vehicle (1) and/or at the trailer (20), so that, as a function of the sensor parameters, a braked curved trajectory and/or unbraked or braked driving downhill can be recognized.

22. A device for stabilizing a tractor-trailer combination (30), such that at least the tractor vehicle (1) can be steered at its front and rear axles and comprises at least one control unit according to claim 18, wherein, driving unbraked round a curved trajectory and/or when driving downhill, the wheels (4, 5) on the rear axle of the tractor vehicle (1) are set at a steering angle which is in the same direction as the wheels (2, 3) on the front axle in order to stabilize the tractor-trailer combination (30).

23. The device according to claim 22, wherein the stabilizing steering angle, at the rear axle, is adjusted as a function of the parameters evaluated by the control unit.

24. The device according to claim 23, wherein at least one of the steering at the front axle and/or the rear axle is in a form of a steer-by-wire steering system.

Description

BRIEF DESCRIPTION OF THE DRAWING

[0024] Below, the invention will be described with reference to a preferred embodiment, having regard to the drawing.

[0025] FIG. 1 shows a view of a tractor-trailer combination, seen from above.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT(S)

[0026] The single FIGURE shows a schematic view from above, of a tractor vehicle 1 and a trailer 20. The tractor vehicle 1 has a front axle with wheels 2 and 3. In addition, a rear axle is shown with wheels 4 and 5. A towing hitch 8 is attached at the rear of the vehicle. A coupling ball 9 is arranged at the end of the towing hitch 8.

[0027] The trailer 20 has a trailer axle with wheels 26 and 27. A trailer coupling 28 is arranged at the front of the trailer. The trailer 20 is coupled to the tractor vehicle 1, in that the coupling 28 is rotatably fitted onto the coupling ball 9 of the towing hitch 8 in the usual manner. The indicated angle α shows the combination angle, also called the articulation angle.

[0028] The tractor-trailer combination 30 is being braked while driving round a curved trajectory. In order to drive round the curve, a wheel steering angle δ.sub.v to the left is set at the front wheels 2 and 3. A wheel steering angle δ.sub.h in the same direction, namely to the left, is set at the rear wheels 4 and 5. The tractor vehicle is decelerated by a braking force F.sub.Brems, so braked cornering is initiated and carried out. Owing to the deceleration of the tractor vehicle 1 by the braking process, the trailer 20 moves in the direction of the rear of the tractor vehicle, so that the force denoted by F.sub.Trag acts upon the common pivot point at the coupling ball. This increases the yaw torque M.sub.Gier of the tractor vehicle about its vertical axis. By virtue of the steering angles in the same direction shown on the tractor vehicle, the tractor-trailer combination 30 is stabilized. Accordingly, the tractor vehicle or the trailer do not break apart and the intended trajectory of the curve to the left can be maintained.

[0029] The invention does not relate solely to passenger motor vehicles but is also appropriate for tractor-trailer combinations in the utility vehicle sector. Likewise, trailers with more than one axle can be used.

INDEXES

[0030] 1 Tractor vehicle [0031] 2, 3 Front axle wheels [0032] 4, 5 Rear axle wheels [0033] 8 Towing hitch [0034] 9 Towing ball [0035] 20 Trailer [0036] 26, 27 Trailer axle wheels [0037] 28 Trailer coupling [0038] 30 Tractor-trailer combination [0039] M.sub.Gier Tractor vehicle yaw torque [0040] F.sub.Brems Tractor vehicle braking force [0041] F.sub.Trag Trailer inertia force [0042] α Combination angle, articulation angle [0043] δ.sub.v Wheel steering angle, front axle [0044] δ.sub.h Wheel steering angle, rear axle