Interrelated power delivery controls – including engine control – Transmission control – With brake control
Reexamination Certificate
2000-04-12
2001-09-11
Marmor, Charles A (Department: 3681)
Interrelated power delivery controls, including engine control
Transmission control
With brake control
C477S107000, C477S118000
Reexamination Certificate
active
06287237
ABSTRACT:
BACKGROUND OF THE INVENTION
Field of the Invention
The invention lies in the automotive technology field. More specifically, the invention relates to a method and a control configuration for controlling the drive train of a motor vehicle. Such a drive train controller includes, on the one hand, an engine and an engine controller by means of which variables which influence the engine torque, for example the ignition timing and the metering of fuel to the cylinders, are controlled. On the other hand, it also includes an automatic transmission and a transmission controller by means of which shifting operations of the automatic transmission are controlled.
In prior art transmission controllers for motor vehicles, the transmission ratio of the transmission is set automatically in dependence on the position of the gas pedal and of the driving velocity by reference to stored characteristic diagrams. Instead of the position of the gas pedal in the narrower sense, it is also possible to use the signal of a so-called electronic accelerator pedal (E-Gas) or a different variable derived from the engine torque which the driver requests. In this context, various driving parameters and operating conditions of the motor vehicle are taken into account. See, for example, U.S. Pat. No. 5,957,990 (international publication WO 97/01051). The gear speed which is to be respectively engaged or—in the case of infinitely variable transmissions—the transmission ratio which is to be set is selected by control switching operations which operate, for example, using the methods of fuzzy logic. With this logic, the knowledge of experts which has been acquired through experience is described in the form of a so-called rule base and is thus used for the closed-loop or open-loop control operations of the motor vehicle transmission. The logic circuit generates control signals with which, inter alia, the transmission ratio of the transmission is defined.
A prior art integrated drive train controller for a motor vehicle interprets the position of the gas pedal and the brake pedal as a wheel torque which is required by the driver. See U.S. Pat. No. (Ser. No. 08/937,253) and German published patent application DE 196 37 210 A1. It has a calculation device by means of which the positions of the gas pedal and of the brake pedal are received and from which central control parameters for the drive sources and the decelerating units of the drive train are generated.
It is known to generate the setpoint braking torques intended for the drive wheels of a vehicle by means of engine braking torques and operating braking torques. See U.S. Pat. No. 5,613,743 and German published patent application DE 42 30 101 A1.
Furthermore, U.S. Pat. No. 5,514,050 (German published patent application DE 43 30 391 A1) discloses a method for controlling a drive train of a motor vehicle in which a brake signal that is triggered by the driver by activating the brake pedal generates an engine braking torque as a function of the braking effect by shifting down the automatic transmission. The engine braking torque can be metered here either constantly or variably in accordance with a characteristic curve.
There exist driving situations in which an activation of the brakes by the driver should expediently be supported by the drive train of the motor vehicle.
SUMMARY OF THE INVENTION
The object of the invention is to provide a method of controlling the drive train of a motor vehicle and a drive train controller which overcome the above-noted deficiencies and disadvantages of the prior alert devices and methods of this kind, and which detect a braking requirement by the driver and effectively support the required braking effect by controlling the transmission ratio of the automatic transmission.
With the above and other objects in view there is provided, in accordance with the invention, 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.
In accordance with an added feature of the invention, the converting step comprises converting the brake signal into a required braking torque as a function of various operating parameters of the motor vehicle.
In accordance with an additional feature of the invention, 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.
In accordance with another feature of the invention, the characteristic curves of the down-shift characteristic diagram are defined with reference to a maximum desired rotational speed after a shifting-down operation.
In accordance with a further feature of the invention, a lower limit for permissible shifting-down operations is included in the down-shift characteristic diagram.
In accordance with again an added feature of the invention, the transmission ratio is adaptively determined with reference to a driving style and a driving situation.
In accordance with again an additional feature of the invention, setpoint values for the torque are determined on a basis of the required braking torque, for all electronically controllable braking assemblies present in the motor vehicle.
In accordance with again a further feature of the invention, the required braking torque is distributed among the electronically controllable braking assemblies present in the motor vehicle as a function of various operating parameters of the motor vehicle.
With the above and other objects in view there is also provided, in accordance with the invention, 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 the engine controller and to the transmission controller, the 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.
In accordance with a concomitant feature of the invention, the motor vehicle has a plurality of electronically controlled braking assemblies each connected to and controlled by the central control unit.
In summary, according to the invention, activations of the brake pedal by the driver are interpreted as a requirement for braking torque. The gear speed selection is then made using torque-based shifting-down characteristic curves. The engine characteristic can be transmitted with significant variables from the engine controller to the transmission controller in compressed form, i.e. with a very small amount of data, in order to decouple the two systems as much as possible. The shifting-down characteristic curves are defined as independently of the engine as possible and in particular do not contain a torque model of the engine.
The engine characteristic is concentrated on the interface between the transmission and the engine. The shifting-down characteristic curves can thus be defined to a large extent
Graf Friedrich
Gutknecht-Stöhr Florian
Probst Gregor
Greenberg Laurence A.
Lerner Herbert L.
Marmor Charles A
Pang Roger
Siemens Aktiengesellschaft
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