Data processing: vehicles – navigation – and relative location – Vehicle control – guidance – operation – or indication – Vehicle diagnosis or maintenance indication
Reexamination Certificate
2001-12-07
2004-12-21
Nguyen, Thu V. (Department: 3661)
Data processing: vehicles, navigation, and relative location
Vehicle control, guidance, operation, or indication
Vehicle diagnosis or maintenance indication
Reexamination Certificate
active
06834221
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a method of operating a motor vehicle with an engine, at least one drive axle with at least one wheel, a torque transfer system between the engine and the drive axle, and a wheel rpm sensor device.
The invention further relates to a method of operating a motor vehicle which, in addition to the aforementioned elements, is further equipped with a control device.
An engine in the context of the present invention is an internal combustion engine such as a gasoline or diesel engine.
A torque transfer system in the sense of the present invention is an arrangement with the capability to convert a rotary input quantity of an input shaft into an identical or different rotary output quantity of an output shaft and/or with the capability to couple and uncouple the input shaft and the output shaft. A torque transfer system can include a clutch device and/or a transmission device and/or a torque converter device or any other mechanism in the same general category.
A transmission device in the sense of the present invention is a mechanism that can be shifted in steps or in a continuous, step-less range into different shift positions corresponding to different transmission ratios between two shafts of the transmission device. The transmission device can be shifted automatically or manually, or in a partially automatic or automated mode with the possibility of manual intervention, or in some other way. Depending on the design of the transmission device, the shifts may be performed with or without an interruption in vehicle traction.
A transmission device in the sense of the present invention encompasses in particular manually operated step-shifting transmissions, or cone-pulley transmissions, or automatic transmissions, or automated step-shifting transmissions or the like.
An automatic transmission in the present context is a transmission device in which the shifts are controlled automatically and occur without interruption in the tractive force, specifically with a planetary gear mechanism.
The term “automated shift transmission” relates to a transmission device that allows automatic shifting between different shift positions and is characterized by an interruption in vehicle traction during the shift processes.
A rotary input/output quantity or other characteristic rotary quantity is used to characterize the dynamic situation of a rotating part, particularly a shaft. Specific examples of characteristic rotary quantities are a torque or an rpm rate.
A clutch device in the sense of the present invention encompasses torque-coupling devices configured as a friction clutch, a start-up clutch, a reverse-gear clutch, a magnet-powder clutch, a converter bypass clutch, or any other device of the same general category. The term “clutch device” in the present context relates in particular to an electronically controlled clutch device in which the movement between different positions of the clutch can be performed under electronic control.
A specific example of an electronically controlled clutch device is represented by a device which has been described by and is available from the assignee of the present invention under the name “Electronic Clutch Management (ECM)”.
A wheel rpm sensor device can detect wheel rpm rates either at discrete time intervals or continuously.
State-of-the-art methods of operating a motor vehicle are known in which the rpm rate of at least one wheel of the motor vehicle is detected by a sensor device. The detected wheel rpm rates are used to calculate the speed of the vehicle or to control the actuation of a clutch in an electronically controlled clutch device, or similar processes.
The detection of wheel rpm rates is a proven concept, having been used for many years. Experience has likewise been positive and improvements have been achieved by using the detected wheel rpm rates for the management of electronically controlled clutch devices, as this concept allows for example certain engagement positions of the clutch device to be determined without the use of an additional sensor on the transmission input- or output shaft. For example the amount of torque transmitted through the clutch device can be determined based on the engine torque, the engine rpm rate, a wheel rpm rate, and the transmission ratio.
However, experience has also shown that there can be malfunctions in the detection of wheel rpm rates, particularly in case of a failure of a wheel rpm sensor. As a consequence of these errors, a wrong vehicle speed may be calculated, or clutch and transmission movements may be performed incorrectly.
The detected wheel rpm rates are further used in many control applications with the implied assumption that the vehicle is traveling at a speed according to the functional relationship between vehicle speed and wheel rpm rate.
Experience has also shown that this assumption is not always justified.
OBJECT OF THE INVENTION
The present invention therefore has the objective of providing a method of operating a motor vehicle, as well as providing a motor vehicle, with a means to recognize functional impairments in wheel rpm sensors, to distinguish reliable rpm rates that may be used for calculating vehicle speed or similar information from non-reliable rpm rates that cannot be used for assuring the operating safety of the vehicle. It is also part of the objective, after a detected wheel rpm rate has at some point been found to be non-reliable, to determine when it is safe again to use that detected rpm rate for control purposes or other critical uses, or to determine when a malfunctioning wheel rpm sensor device has regained its functionality.
SUMMARY OF THE INVENTION
To meet the foregoing objective, the invention proposes a method of operating a motor vehicle in which a determination is made whether a wheel is rolling, or spinning with slippage, or locked, and/or whether or not the wheel rpm sensor device is functioning properly. When making this determination, a substitute wheel rpm rate value is calculated and compared with the detected wheel rpm rate.
With particular preference, this comparison is used to determine whether or not the wheel rpm sensor device is functionally impaired, and whether the respective wheel is rolling, spinning with slip, or locked up.
In the inventive method, at least one first characteristic operating value of the motor vehicle or specifically of a wheel of the vehicle is determined, monitored and/or evaluated in order to identify implausible wheel rpm rates and distinguish them from plausible wheel rpm values.
A plausible wheel rpm rate in the sense of the present invention means in particular an rpm rate that conforms to a predetermined functional relationship with the vehicle speed, which may be expressed by the equation v=C×n/60, where v stands for the vehicle speed in meters per second, C for the wheel circumference in meters, and n for the wheel rpm rate, i.e., the number of revolutions per minute. According to this equation, a wheel rpm rate is plausible if the wheel is rolling without slippage, or if the vehicle is standing still and the wheel is not turning.
In the present context, a detected wheel rpm rate would be referred to as implausible in one of the following cases: if a wheel rpm rate is correctly detected but the wheel is not rolling (meaning that it is spinning without gripping the pavement), or if a wheel rpm rate of zero is detected while the vehicle is in motion, or if an rpm rate other than zero is detected while the vehicle is standing still, or if there are discrepancies between the actual and the detected or indicated wheel rpm rate.
In the present context, the terms “plausible” and “implausible” may be applied to either the actual or the detected wheel rpm rate.
Under the inventive method, after a wheel rpm rate has been found to be implausible, at least one second characteristic operating value of the vehicle and/or of a wheel is monitored. This monitoring activity serves to determine whether the wheel rpm rate remains implausible, and/or whether as well
Henneberger Klaus
Jäger Thomas
Zimmermann Martin
Darby & Darby
LuK Lamellen und Kupplungsbau Beteiligungs KG
Nguyen Thu V.
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