Interrelated power delivery controls – including engine control – Transmission control – Transmission controlled by engine
Reexamination Certificate
1999-08-16
2001-06-26
Estremsky, Sherry (Department: 3681)
Interrelated power delivery controls, including engine control
Transmission control
Transmission controlled by engine
C123S350000, C123S399000, C477S115000
Reexamination Certificate
active
06251044
ABSTRACT:
FIELD OF THE INVENTION
The invention relates to a method and an arrangement for controlling a drive unit of a motor vehicle.
BACKGROUND OF THE INVENTION
U.S. Pat. No. 5,692,472 discloses that a maximum permissible engine torque or a maximum permissible engine power is derived on the basis of at least one operating variable, for example, the accelerator pedal position. This maximum permissible engine torque or maximum permissible engine power is compared to the actual torque or the actual power of the drive unit. Fault reaction measures are initiated when the actual value exceeds the maximum permissible value. These measures can include switching off the metering of fuel until the actual value again drops below the maximum permissible value.
With the monitoring measures described, there is a conflict of objectives with respect to the functionality of the drive unit and the precision of the described monitoring. At least in some operating states such as when the accelerator pedal is in the idle position, a relatively large torque or a relatively large power must be permitted so that the idle control can compensate for disturbance quantities such as a switched-in climate control compressor, a steering-assist pump or a grinding of the clutch. In such operating situations, the maximum permissible values must be set to values which can already lead to an unwanted acceleration of the vehicle in the case of a fault.
SUMMARY OF THE INVENTION
It is an object of the invention to solve the above target conflict or conflict of objectives.
The method of the invention is for controlling a drive unit of a motor vehicle and the method includes the steps of: detecting the rpm (Nmot) of the drive unit and forming the time-dependent change (dNmot/dt) of the rpm (Nmot); determining at least one quantity of the following quantities: torque, power or throttle flap angle; determining the maximum permissible value of the at least one quantity while considering the time-dependent change (dNmot/dt) of the rpm (Nmot) of the drive unit; and, initiating a fault reaction measure when the at least one quantity exceeds the maximum permissible value.
The described target conflict between the functionality of the drive unit and the precision of the monitoring is successfully solved. It is especially advantageous that in operating situations, in which a relatively high permissible value must be pregiven in order to prevent an unintended response of the monitoring function, a permissible value is pregiven which is greater compared to other operating situations without it leading to an unwanted acceleration of the vehicle in the case of a fault.
It is especially advantageous to tie in the time-dependent change of the engine rpm when determining the permissible value. This is so, because, in this way, and for a negative time-dependent change, an increase of the permissible value can be undertaken whereas, for an increasing or constant rpm, a relatively low permissible value is pregiven. In the case of a fault, unwanted accelerations are substantially prevented because, as a rule, a falling rpm precludes unwanted accelerations. Accordingly, when disturbance quantities such as climate control compressor, power steering, clutch actuation, et cetera lead to a sudden drop in rpm, the idle control effectively compensates this drop without the monitoring function responding.
It is advantageous to allow the increase of the permissible value only in specific operating situations and especially only when the accelerator pedal is in the idle position (released).
It is especially advantageous to maintain the increase of the permissible value for negative rpm changes for a pregiven time span after the end of the drop in rpm because, in this way, the idle control can control the rpm very rapidly to the pregiven value after the drop in rpm.
REFERENCES:
patent: 5692471 (1997-12-01), Zhang
patent: 5692472 (1997-12-01), Bederna et al.
patent: 5782221 (1998-07-01), Woldt
patent: 6029625 (2000-02-01), Bischof et al.
patent: 63-109264 (1988-05-01), None
Estremsky Sherry
Lewis Tisha D.
Ottesen Walter
Robert & Bosch GmbH
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