Torque vectoring having automatic yaw torque equalization

Abstract

A method and a system for automatic yaw torque equalization (AYTE) in an electrically driven vehicle having wheel-individual torque distribution (torque vectoring drive).

Claims

1. A method for automatic yaw torque equalization in a vehicle having an electric drive having wheel-individual torque distribution, including at least two electric machines, which each drive one wheel of an axle, comprising: determining whether a vehicle acceleration exceeds a predetermined threshold; if the vehicle acceleration exceeds the predetermined threshold, determining, during a straight-ahead travel of the vehicle in which a steering wheel of the vehicle is in a neutral position, whether a nonzero steering torque occurs; and if the nonzero steering torque occurs, adapting, via an adaptation loop, a target torque demand at the two electric machines until the nonzero steering torque is eliminated.

2. The method according to claim 1, wherein the electric drive having wheel-individual torque distribution includes four electric machines, which each drive one wheel of the vehicle.

3. The method according to claim 1, wherein the electric machines are mounted on a vehicle platform.

4. The method according to claim 3, wherein the electric machines are arranged at the wheels.

5. The method according to claim 3, wherein the electric machines are arranged centrally on the vehicle platform.

6. A system for the automatic yaw torque equalization in a vehicle having an electric drive having wheel-individual torque distribution, comprising: at least two electric machines, which each drive one wheel of an axle, a steering angle sensor and a steering torque sensor, and a control unit, which is configured to provide a target torque demand at the at least two electric machines, wherein the control unit is configured to receive and analyze data on acquired steering angles and steering torques and adapt, via an adaptation loop, the target torque demand at the at least two electric machines until a measured, nonzero steering torque disappears during straight-ahead travel of the vehicle in which a steering wheel of the vehicle is in a neutral position and during an acceleration of the vehicle which exceeds a predetermined threshold.

7. The system according to claim 6, further comprising a vehicle acceleration sensor.

Description

BRIEF DESCRIPTION OF THE DRAWING

(1) The disclosure is schematically illustrated on the basis of one embodiment in the drawing and is described further with reference to the drawing. In the FIGURE:

(2) FIG. 1 shows a flow chart of one embodiment of the function for automatic yaw torque equalization (AYTE).

DETAILED DESCRIPTION

(3) FIG. 1 shows a flow chart 10 of one embodiment of the function for automatic yaw torque equalization (AYTE) in a torque vectoring drive having two electric machines.

(4) At the beginning of the method are the ascertainment of the steering angle 11 and the check 31 as to whether the steering angle is neutral, i.e., straight-ahead travel exists. If this is not the case, the termination 20 of the method occurs.

(5) If straight-ahead travel is present, the ascertainment 12 of the vehicle acceleration a and the check 32 as to whether the vehicle acceleration a is greater than a predetermined threshold value follow. If this is not the case, the termination 20 of the method occurs.

(6) If the vehicle acceleration a is greater than the threshold value, i.e., if the electric machines generate a significant drive torque, the ascertainment 13 of the steering torque M and the check 33 as to whether the steering torque M is nonzero follow. If the steering torque M is equal to zero, the end 20 of the method is reached.

(7) If it is established that a nonzero steering torque M is present, an adaptation loop 40 thus begins. If the steering torque M is less than zero, a reduction 14 of the target torque of the left electric machine occurs. If the steering torque M is greater than zero, a reduction 15 of the target torque of the right electric machine occurs. In an alternative embodiment (not shown), the signs of an occurring steering torque are reversed because of a producer-specific orientation. In this case, in the event of a steering torque less than zero, the target torque of the right electric machine is reduced, and in the event of a steering torque greater than zero, the target torque of the left electric machine is reduced.

(8) An ascertainment 13 of the steering torque M is subsequently performed again. This loop 40 is run through until the steering torque M is adjusted out, i.e., has the value zero. A steering torque M of zero means that the actual torques of the electric machines are equal. The ratio of the target torques at which the actual torques of the electric machines are equal is stored and is used as a correction factor in the control of the electric machines.