Process and device for setting a driving torque

Details Process and device for setting a driving torque Process and device for setting a driving torque

1998-08-06

2001-01-30

Chin, Gary (Department: 3661)

Data processing: vehicles, navigation, and relative location

Vehicle control, guidance, operation, or indication

Indication or control of braking, acceleration, or deceleration

C701S083000, C701S085000, C701S086000, C180S197000

Reexamination Certificate

active

06182003

ABSTRACT:

FIELD OF THE INVENTION
The present invention relates to a method of and a device for setting a driving torque.
BACKGROUND INFORMATION
German Patent Application No. 42 39 711 describes a system for setting an engine torque, where a desired engine torque which is selected by the driver and by an anti-slip regulation system is achieved by varying the air supply, the firing point and/or the quantity of fuel injected.
German Patent Application No. 40 30 881 (corresponding to U.S. Pat. No. 5,445,442) describes an anti-slip regulation system where the anti-slip regulatorler is divided into a cardan speed controller and a differential speed controller.
German Patent Application No. 42 29 560 (corresponding to U.S. Pat. No. 5,443,307) describes an anti-slip regulation system where the controller properties are improved by means of a differential speed controller so that the differential blocking effect is improved by the operation affecting the brakes.
German Patent Application No. 19542294.5 and the article “FDR-Fahrdynamikregelung von Bosch” (FDR Regulation of Driving dynamics by Bosch) in ATZ Automobiltechnische Zeitschrift, (Automotive Engineering Journal) 96 (1994) describe a subordinate anti-slip regulationler as part of regulation of driving dynamics, where a distinction is made between a cardan torque acting on all driven wheels and a differential torque acting between the driving wheels to set the driving torque. To set the driving torque as part of anti-slip regulation, the desired cardan torque and the differential torque are distributed to the available actuators to set the driving torque. Operations affecting the wheel brakes and/or operations involving the control of the vehicle engine are available for this. These effects to differ in their different dynamic responses.
The object of the present invention is to achieve an optimum distribution of the driving torque requirement to the available torque operation options.
SUMMARY OF THE INVENTION
The invention relates to a method of setting a driving torque in a motor vehicle, particular to setting the torque as part of anti-slip regulation. At least two triggerable actuators are available for influencing the driving torque, with the actuators having different dynamic responses with regard to setting a driving torque.
The invention provides first a component of the driving torque to be set is determined, and the component thus determined is used to trigger the actuator with the lower dynamics. In addition, the change in driving torque due to this triggering of the actuator with the lower dynamics is estimated. The difference between the driving torque to be set and the estimated driving torque is then used to trigger at least one actuator with higher dynamics.
This method yields an optimum distribution of the driving torque requirement, which takes into account the different dynamics of the actuators, to the available torque operation options. In particular, the method according to the present invention provides that only a portion of the total driving torque requirement, specifically the steady-state component, is used to control the slow-acting torque operation option. The faster-acting operations are then selected pursuant to the remaining component and pursuant to the torque which cannot be achieved instantaneously through the slow-acting torque operation option.
If the setting of the driving torque according to the present invention is a driving torque reduction to be set as part of anti-slip regulation (ASR), then as invention yields a uniform ASR interface for various engine control units.
Another embodiment of the present invention provides that an integral component of the driving torque that is to be set is determined as the component of the driving torque to be set. Thus, only the torque request pending for a longer time is implemented by the slow-acting operation, while the short-term requirements are implemented only by the faster-acting operations.
If the motor vehicle has a gasoline engine, it is possible to provide according to the present invention for the actuator with the lower dynamics to vary the air supply, in particular the throttle valve setting, while the actuators of higher dynamics vary the firing point, the fuel supply, and/or the braking force on the driven wheels.
The estimate according to the present invention of the change in driving torque brought about by the triggering of the actuator with the lower dynamics can be accomplished using an engine model. If the triggering of the actuator with the lower dynamics takes place using an actuating signal, this estimate is made by filtering the actuating signal using a time filter (PT
1
element) and/or a lag element (T
t
element).
It is further advantageous that the component for triggering the actuator with the lower dynamics is determined in such a way that only positive driving torques are set. This means that a dragging operation or braking action of the vehicle engine is not allowed.
In addition, an further embodiment of the present invention provides that the component for triggering the actuator with the lower dynamics is determined in such a way that the driving torque is limited to a minimum positive value when there is a low longitudinal velocity of the vehicle and/or when there are different coefficients of friction of a certain value on the two sides of the vehicle (&mgr;
split
condition). In particular, when starting under a split condition (different coefficients of friction on the driving wheels), the engine torque achieved by varying the air supply should be limited to a value much greater than zero. This yields faster traction after reducing the drive slip, e.g., by changing the coefficient of friction.
Another advantageous embodiment of the present invention provides that the actuator of the higher dynamics varies the quantity of fuel, with this change taking place in particular by reducing the amount of fuel metered to individual cylinders of the engine of the vehicle. The triggering of this actuator over a predeterminable period of time is predicted, whereupon the triggering is then suppressed when the predicted triggering is below a threshold value. This embodiment provides that reduction of the fuel injection generally acts on the driving torque only with a rather great delay. For this reason, the triggering is predicted over this lag time and it causes a reduction in fuel injection only when the prediction still indicates a desired fuel reduction at the time when the fuel reduction starts having the effect of reducing the driving torque.
In addition, it is possible to provide that in the case of a change in the amount of fuel, in particular due to the reduction in fuel metered to individual cylinders of the vehicle engine, this change is reduced or suppressed when the drive slip of the driving wheel (high wheel) having the higher coefficient of friction is below a threshold value. This is done for reasons of comfort, because the high wheel which is preferably responsible for the forward motion of the vehicle due to the low drive slip should not be braked abruptly. This would lead to jerking motion which would diminish comfort.
The object of the present invention is also to provide a device for carrying out the method described above for setting a driving torque in a motor vehicle.


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Vo Anton van Zanten et al., “FDR-Fahrdynamik regelung von Bosch”, ATZ Automobiltechnische Zeitschrift, 96 (1994), pp. 674-689.

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