Vehicle dynamics control system in a motor vehicle and electronic vehicle dynamics control unit for a vehicle dynamics control system

Abstract

A vehicle dynamics control system in a motor vehicle includes an electronic vehicle dynamics control unit which is connected to at least one drive control unit and is configured so as to: determine at least one setpoint slip or a setpoint slip corridor and an actual vehicle speed as a reference speed, and transmit the at least one setpoint slip or the setpoint slip corridor together with the reference speed to the at least one drive control unit. The drive control unit, in accordance with the transmitted values and by way of a function module, determines setpoint rotational speed values at a motor level and carries out a rotational speed control process.

Claims

1. A vehicle dynamics control system in a motor vehicle, comprising: an electronic vehicle dynamics control unit connected to and distinct from at least one electronic drive control unit and configured to: determine at least one slip setpoint or a slip setpoint corridor and an actual vehicle speed as a reference speed; and transmit the at least one slip setpoint or the slip setpoint corridor together with the reference speed to the at least one electronic drive control unit, wherein the at least one electronic drive control unit, in accordance with the transmitted slip setpoint or slip setpoint corridor, is configured to determine setpoint rotational speed values at a motor level and carry out a rotational speed control process.

2. The vehicle dynamics control system as claimed in claim 1, wherein the slip setpoint corridor is predefined by a minimum permissible slip setpoint for an overrun mode and by a maximum permissible slip setpoint for a traction mode, and/or the rotational speed setpoint corridor is predefined by a minimum permissible rotational speed threshold for the overrun mode and by a maximum permissible rotational speed threshold for the traction mode.

3. The vehicle dynamics control system as claimed in claim 2, wherein the at least one electronic drive control unit further comprises: a first electronic drive control unit configured to control a first drive motor for driving a first axle; and a second electronic drive control unit, distinct from the first electronic drive control unit and the vehicle dynamics control unit, configured to control a second drive motor for driving a second axle; and the vehicle dynamics control unit is further configured to: determine a minimum permissible rotational speed threshold and/or a minimum permissible slip setpoint for the first axle, determine a maximum permissible rotational speed threshold and/or a maximum permissible slip setpoint for the first axle, determine a minimum permissible rotational speed threshold and/or a minimum permissible slip setpoint for the second axle, determine a maximum permissible rotational speed threshold and/or a maximum permissible slip setpoint for the second axle, and output at least one of the determined minimum permissible rotational speed threshold for the first axle, minimum permissible slip setpoint for the first axle, maximum permissible rotational speed for the first axle, maximum permissible slip setpoint for the first axle, minimum permissible rotational speed threshold for the second axle, minimum permissible slip setpoint for the second axle, maximum permissible rotational speed threshold for the second axle, or maximum permissible slip setpoint for the second axle to the first and/or second electronic drive control unit.

4. The vehicle dynamics control system as claimed in claim 1, wherein the at least one electronic drive control unit further comprises: a first electronic drive control unit configured to control a first drive motor for driving a first axle; and a second electronic drive control unit, distinct from the first electronic drive control unit and the vehicle dynamics control unit, configured to control a second drive motor for driving a second axle; and the vehicle dynamics control unit is further configured to: determine a minimum permissible rotational speed threshold and/or a minimum permissible slip setpoint for the first axle, determine a maximum permissible rotational speed threshold and/or a maximum permissible slip setpoint for the first axle, determine a minimum permissible rotational speed threshold and/or a minimum permissible slip setpoint for the second axle, determine a maximum permissible rotational speed threshold and/or a maximum permissible slip setpoint for the second axle, and output at least one of the determined minimum permissible rotational speed threshold for the first axle, minimum permissible slip setpoint for the first axle, maximum permissible rotational speed for the first axle, maximum permissible slip setpoint for the first axle, minimum permissible rotational speed threshold for the second axle, minimum permissible slip setpoint for the second axle, maximum permissible rotational speed threshold for the second axle, or maximum permissible slip setpoint for the second axle to the first and/or second electronic drive control unit.

5. The vehicle dynamics control system as claimed in claim 4, wherein in the case of all wheel drives, a differential slip control process is configured to be carried out in which the at least one slip setpoint for one axle of the first and second axles is predefined as a function of an actual slip value of the other axle.

6. The vehicle dynamics control system as claimed in claim 4, further comprising: an actuator configured to be actuated by the rotational speed control process, wherein the at least one electronic drive control unit is positioned more closely to the actuator than the electronic vehicle dynamics control unit.

7. The electronic vehicle dynamics control unit for a vehicle dynamics control system as claimed in claim 1, wherein the electronic vehicle dynamics control unit is further configured to: (i) determine at least one wheel-related or axle-related minimum permissible slip setpoint, and/or (ii) determine at least one wheel-related or axle-related minimum permissible rotational speed threshold and at least one wheel-related or axle-related maximum permissible slip setpoint, and/or (iii) determine at least one wheel-related or axle-related maximum permissible rotational speed threshold, and (iv) transmit at least one of the determined minimum permissible slip setpoint, minimum permissible rotational speed threshold and maximum permissible slip setpoint, or maximum permissible rotational speed threshold to the at least one drive unit in order to enable the at least one drive unit to perform the rotational speed control process itself as a function of the transmitted values.

8. The vehicle dynamics control system as claimed in claim 1, further comprising: an actuator configured to be actuated by the rotational speed control process, wherein the at least one electronic drive control unit is positioned more closely to the actuator than the electronic vehicle dynamics control unit.

9. A vehicle dynamics control system in a motor vehicle, comprising: an electronic vehicle dynamics control unit connected to and distinct from at least one electronic drive control unit and configured to: determine at least one slip setpoint or a slip setpoint corridor and an actual vehicle speed as a reference speed, determine a rotational speed setpoint in accordance with the at least one slip setpoint or a rotational speed setpoint corridor in accordance with the slip setpoint corridor, and transmit the rotational speed setpoint or the rotational speed setpoint corridor to the at least one electronic drive control unit, wherein the at least one electronic drive control unit, in accordance with the transmitted rotational speed setpoint or rotational speed setpoint corridor, is configured to carry out a rotational speed control process for compensating an impermissible deviation from the rotational speed setpoint or from the rotational speed setpoint corridor.

10. The vehicle dynamics control system as claimed in claim 9, wherein the slip setpoint corridor is predefined by a minimum permissible slip setpoint for an overrun mode and by a maximum permissible slip setpoint for a traction mode, and/or the rotational speed setpoint corridor is predefined by a minimum permissible rotational speed threshold for the overrun mode and by a maximum permissible rotational speed threshold for the traction mode.

11. The vehicle dynamics control system as claimed in claim 10, wherein the at least one electronic drive control unit further comprises: a first electronic drive control unit configured to control a first drive motor for driving a first axle; and a second electronic drive control unit, distinct from the first electronic drive control unit and the vehicle dynamics control unit, configured to control a second drive motor for driving a second axle; and the vehicle dynamics control unit is further configured to: determine a minimum permissible rotational speed threshold and/or a minimum permissible slip setpoint for the first axle, determine a maximum permissible rotational speed threshold and/or a maximum permissible slip setpoint for the first axle, determine a minimum permissible rotational speed threshold and/or a minimum permissible slip setpoint for the second axle, determine a maximum permissible rotational speed threshold and/or a maximum permissible slip setpoint for the second axle, and output at least one of the determined minimum permissible rotational threshold for the first axle, minimum permissible slip setpoint for the first axle, maximum permissible rotational speed threshold for the first axle, maximum permissible slip setpoint for the first axle, minimum permissible rotational speed threshold for the second axle, minimum permissible slip setpoint for the second axle, maximum permissible rotational speed threshold for the second axle, or maximum permissible slip setpoint for the second axle to the first and/or second electronic drive control unit.

12. The vehicle dynamics control system as claimed in claim 9, wherein the at least one electronic drive control unit further comprises: a first electronic drive control unit configured to control a first drive motor for driving a first axle; and a second electronic drive control unit, distinct from the first electronic drive control unit and the vehicle dynamics control unit, configured to control a second drive motor for driving a second axle; and the vehicle dynamics control unit is further configured to: determine a minimum permissible rotational speed threshold and/or a minimum permissible slip setpoint for the first axle, determine a maximum permissible rotational speed threshold and/or a maximum permissible slip setpoint for the first axle, determine a minimum permissible rotational speed threshold and/or a minimum permissible slip setpoint for the second axle, determine a maximum permissible rotational speed threshold and/or a maximum permissible slip setpoint for the second axle, and output at least one of the determined minimum permissible rotational speed threshold for the first axle, minimum permissible slip setpoint for the first axle, maximum permissible rotational speed for the first axle, maximum permissible slip setpoint for the first axle, minimum permissible rotational speed threshold for the second axle, minimum permissible slip setpoint for the second axle, maximum permissible rotational speed threshold for the second axle, or maximum permissible slip setpoint for the second axle to the first and/or second electronic drive control unit.

13. The vehicle dynamics control system as claimed in claim 12, wherein in the case of all wheel drives, a differential slip control process is configured to be carried out in which the at least one slip setpoint for one axle of the first and second axles is predefined as a function of an actual slip value of the other axle.

14. The vehicle dynamics control system as claimed in claim 9, further comprising: an actuator configured to be actuated by the rotational speed control process, wherein the at least one electronic drive control unit is positioned more closely to the actuator than the electronic vehicle dynamics control unit.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 is a schematic view of the components which are essential for the method according to the invention and their method of action in a motor vehicle with a rear wheel drive and just one drive motor by way of example as well as, with a setpoint slip interface here.

(2) FIG. 2 is a schematic view of the components which are essential for the method according to the invention and their method of action in a motor vehicle with a road-coupled axle hybrid all-wheel drive as well as, by way of example, with a setpoint rotational speed interface here.

(3) FIG. 3 is a schematic view of the prior art.

DETAILED DESCRIPTION OF THE DRAWINGS

(4) FIG. 1 is a schematic illustration of a vehicle dynamics control system for a motor vehicle 1 or in a motor vehicle 1 with an electronic vehicle dynamics control unit 2, which unit is connected to an electronic drive control unit 3. The electronic drive control unit 3 is provided, for example, for controlling an internal combustion engine 4 for driving a rear axle HA.

(5) The vehicle dynamics control unit 2 is configured, in particular by way of correspondingly programmed function modules, for example by a setpoint value generating module S, in such a way that firstly, as in the prior art described above, the actual vehicle longitudinal speed v.sub.x is determined as a reference speed or reference rotational speed, for example, from the measured wheel rotational speeds n.sub.VL, n.sub.VR, n.sub.HL and n.sub.HR as well as from the signal a.sub.x of a longitudinal acceleration sensor. Furthermore, a setpoint slip S.sub.setp for the rear axle HA is determined from the lateral acceleration a.sub.y, the coefficient of friction μ, the yaw rate deviation ΔΨ/dt and the vehicle longitudinal speed v.sub.x. In this context, a minimum permissible setpoint slip S.sub.setp_min for the overrun mode and a maximum permissible setpoint slip S.sub.setp_max for the traction mode are preferably determined.

(6) In this exemplary embodiment, a setpoint slip corridor in the form of the setpoint slip values S.sub.setp_min_HA and S.sub.setp_max_HA is therefore transmitted, together with the vehicle longitudinal speed v.sub.x as a reference speed, to the drive control unit 3. The drive control unit 3 itself calculates therefrom, with knowledge of the dynamic wheel radius, the respectively necessary setpoint rotational speed N_min for the overrun mode and N_max for the traction mode:
N_min=v.sub.x×(1−S.sub.setp_min_HA)
N_max=v.sub.x×(1+S.sub.setp_max_HA)

(7) Furthermore, the actual rotational speed N.sub.M_act of the drive motor 4 is detected by the drive control unit 3. In a correspondingly programmed rotational speed control module NR1, the rotational speed difference dN.sub.M between the actual rotational speed N.sub.M_act and a value outside the rotational speed band formed by the two motor rotational speed thresholds (N.sub.max/N.sub.min) is then compensated, that is to say in the case of an actual rotational speed N.sub.M_act>N.sub.max or <N.sub.min.

(8) FIG. 2 illustrates a second exemplary embodiment in which a first drive control unit 3 for controlling an internal combustion engine 4 for driving a first axle HA (e.g. rear axle) and a second drive control unit 5 for controlling an electric motor 6 for driving a second axle VA (e.g. front axle) are provided.

(9) With respect to the basic method of functioning according to the invention of the drive control units 3 and 5, reference is made to the statements regarding the drive control unit 3 according to FIG. 1. Firstly, minimum and maximum setpoint slip values S.sub.setp_min and S.sub.setp_max are therefore determined here both for the rear axle HA and for the front axle VA in the vehicle dynamics control unit 2. In contrast to the exemplary embodiment according to FIG. 1, the vehicle dynamics control unit 2 here determines, on the basis of these setpoint slip values and the determined vehicle reference speed v.sub.x, a minimum permissible rotational speed threshold n.sub.min_HA and a maximum permissible rotational speed threshold n.sub.max_HA for the first axle HA as well as a minimum permissible rotational speed threshold n.sub.min_VA and a maximum permissible rotational speed threshold n.sub.max_VA for the second axle VA and outputs them to the first and/or second drive control unit 3 and/or 5.

(10) The setpoint rotational speed corridors determined in this way are in this case transmitted by the vehicle dynamics control unit 2 to the drive control unit 3. The drive control unit 3 is, in particular, also configured by corresponding programming of a function module, e.g. coordination module K1, in such a way that the minimum permissible rotational speed threshold n.sub.min and the maximum permissible rotational speed threshold n.sub.max at the wheel level are respectively converted into a minimum permissible rotational speed threshold N.sub.min and a maximum permissible rotational speed threshold N.sub.max at the drive motor level, provided that the vehicle dynamics control unit 2 does not already predefine these rotational speed thresholds itself at the motor level.

(11) In this example, all the values are output only to the drive control unit 3, which itself processes the minimum permissible rotational speed threshold n.sub.min_HA and the maximum permissible rotational speed threshold n.sub.max_HA for the rear axle HA and passes on the minimum permissible rotational speed threshold n.sub.min_VA and the maximum permissible rotational speed threshold n.sub.max_VA for the front axle VA to the drive control unit 5 for further processing. The rotational speed control processes are subsequently respectively carried out separately for each axle HA and VA by the rotational speed control modules NR1 and NR2 of the two drive control units 3 and 5 in a way analogous to the procedure according to the first exemplary embodiment.

(12) It has been recognized that firstly the rotational speed and/or the slip as setpoint value, instead of the torque as setpoint value, gives rise to more rapid compensation of a slip deviation, and in that secondly the use of a setpoint corridor, instead of a setpoint value, also perceptibly increases comfort.

(13) A development of the invention for all-wheel vehicles according to which, in the case of all-wheel drives, a differential slip control process is carried out during which the predefinition of the setpoint value of one axle (e.g. the front axle) is a function of the actual value of the other axle (e.g. the rear axle) is particularly advantageous. In the application example according to FIG. 2, the setpoint slip of the front axle results from the measured actual slip of the rear axle plus a differential slip factor which can be developed empirically as a function of the driving situation. By means of the differential slip factor it is possible to develop a defined all-wheel driving behavior in a way comparable to a mixed arrangement of tires with different wheel radii on the front and rear axles. This mixed tire arrangement approach has a very positive effect on handling capability and reproducibility in test runs. With the control approach described above it is then possible to render this driving behavior independently of the tire arrangement.

(14) The foregoing disclosure has been set forth merely to illustrate the invention and is not intended to be limiting. Since modifications of the disclosed embodiments incorporating the spirit and substance of the invention may occur to persons skilled in the art, the invention should be construed to include everything within the scope of the appended claims and equivalents thereof.