Method of controlling the drive train of a motor vehicle and drive train controller of a motor vehicle

• US 6,287,237 B1
• Filed: 04/12/2000
• Issued: 09/11/2001
• Est. Priority Date: 04/13/1999
• Status: Expired due to Fees

• Current Assignee: Continental Automotive GmbH (Continental AG)
• Original Assignee: Siemens AG
• Inventors: Probst, Gregor, Gutknecht-Stöhr, Florian, Graf, Friedrich
• Primary Examiner(s): Marmor, Charles A
• Assistant Examiner(s): PANG, ROGER L
• Application Number:
  US09/549,105
• Time in Patent Office: 517 Days
• Field of Search: 477/94, 477/107, 477/118, 477/183
• US Class Current: 477/94
• CPC Class Codes: B60W 10/04 including control of propulsion units
• CPC Class Codes: B60W 10/06 including control of combustion engines
• CPC Class Codes: B60W 10/11 Stepped gearings
• CPC Class Codes: B60W 10/18 including control of braking systems
• CPC Class Codes: B60W 10/196 acting within the driveline, e.g. retarders
• CPC Class Codes: B60W 2520/10 Longitudinal speed
• CPC Class Codes: B60W 2540/12 Brake pedal position
• CPC Class Codes: B60W 2710/0666 Engine torque
• CPC Class Codes: B60W 30/1819 Propulsion control with control means using analogue circuits, relays or mechanical links
• CPC Class Codes: F16H 2061/0096 using a parameter map
• CPC Class Codes: F16H 59/44 dependent on machine speed of the machine, e.g. the vehicle
• CPC Class Codes: F16H 61/0213 characterised by the method for generating shift signals
• CPC Class Codes: F16H 61/21 Providing engine brake control

Abstract

A brake signal which is triggered by the driver by activating the brake pedal is converted into a required braking torque. A setpoint value for the engine drag torque is determined on the basis of the braking torque. The transmission ratio of an automatic transmission is defined automatically as a function of the setpoint value for the engine drag torque by reference to a down-shift characteristic diagram. The characteristic curves of the diagram are defined with reference to the minimum engine torque.

Claims

1. A method of controlling a drive train of a motor vehicle, which comprises:

converting a brake signal issued via a brake pedal of a motor vehicle into a required braking torque;

determining a setpoint value for an engine drag torque based on the required braking torque; and

providing a down-shift characteristic diagram

from which a setpoint transmission ratio to be set can be determined as a function of the setpoint value for the engine drag torque and of a variable functionally associated with a speed of the motor vehicle, and

having characteristic curves defined by taking into account a minimum engine torque; and

automatically setting a transmission ratio of an automatic transmission of the motor vehicle by reference to the down-shift characteristic diagram.

2. The method according to claim 1, wherein the converting step comprises converting the brake signal into a required braking torque as a function of various operating parameters of the motor vehicle.

3. The method according to claim 1, wherein the down-shift characteristic diagram includes the transmission ratio of the transmission as a function of a variable associated functionally with the wheel torque and a variable associated functionally with the speed of the vehicle.

4. The method according to claim 1, which comprises defining the characteristic curves of the down-shift characteristic diagram with reference to a maximally desireable rotational speed after a shifting-down operation.

5. The method according to claim 1, which comprises including a lower limit for permissible shifting-down operations in the down-shift characteristic diagram.

6. The method according to claim 1, which comprises adaptively determining the transmission ratio with reference to a driving style and a driving situation.

7. The method according to claim 1, which comprises determining setpoint values for the torque on a basis of the required braking torque, for all electronically controllable braking assemblies present in the motor vehicle.

8. The method according to claim 7, which comprises distributing the required braking torque among the electronically controllable braking assemblies present in the motor vehicle as a function of various operating parameters of the motor vehicle.

9. A drive train controller of a motor vehicle having an engine and an automatic transmission, comprising:

an engine controller for controlling variables adapted to influence an engine torque;

a transmission controller for controlling a transmission ratio of an automatic transmission of the motor vehicle;

a central control unit connected to said engine controller and to said transmission controller, said central control unit being programmed to;

convert an activation of a brake pedal of the motor vehicle into a required braking torque;

determine a setpoint value for the engine drag torque based on the required braking torque; and

define the transmission ratio of the automatic transmission in dependence on the setpoint value for the

engine drag torque by reference to a down-shift characteristic diagram.

10. The drive train controller according to claim 9, wherein the motor vehicle has a plurality of electronically controlled braking assemblies each connected to and controlled by said central control unit.