Data processing: vehicles – navigation – and relative location – Vehicle control – guidance – operation – or indication – Vehicle diagnosis or maintenance indication
Reexamination Certificate
2001-06-13
2003-02-04
Zanelli, Michael J. (Department: 3661)
Data processing: vehicles, navigation, and relative location
Vehicle control, guidance, operation, or indication
Vehicle diagnosis or maintenance indication
C701S054000, C701S062000
Reexamination Certificate
active
06516255
ABSTRACT:
BACKGROUND OF THE INVENTION
The invention relates to a method of operating a motor vehicle that is equipped with devices that detect the rates of rotation of some or all of the wheels of the vehicle and it also relates to a motor vehicle that is appropriately equipped to perform the inventive method.
Methods of operating a motor vehicle where the rpm-rates of some or all of the wheels are taken into account are known in the existing state of the art.
In a known method of this kind, the rpm-rates of the driven wheels are detected by an arrangement of sensors. The sensor signals are transmitted to a control unit in which the rpm-values are processed and used to regulate or monitor certain parameters of the motor vehicle. For example, the rpm-rates of the wheels may be used to calculate the vehicle speed, at least as long as none of the wheels are slipping on the pavement. Furthermore, by correlating the rpm-rates of the driven wheels with the rpm-rate of the engine of the vehicle, it is possible to find the presence and/or the extent of slippage in the clutch or another torque transmitting system in the power train of the motor vehicle.
Methods of operating a motor vehicle that include detecting and processing the rpm-rates of the vehicle wheels provide a relatively simple way of determining a number of different kinds of instant, real-time data that are helpful in ensuring a reliable operation of the motor vehicle.
However, the methods of the known state of the art suffer from the drawback that they can produce erroneous data. Furthermore, if the erroneous data are used to determine other data such as operating or control parameters, there is a risk that the erroneous data may cause operating errors. Erroneous data and, as a consequence, operating errors can occur, e.g., if at any time the rpm-rates of the wheels as signaled by the rpm sensors are different from the actual rpm-rates, or if at any time the wheel rpm-rates signaled by the rpm sensors do not correlate correctly with other parameters such as the travel speed of the vehicle.
As an example, under certain operating conditions when the transmission is in gear, the input rpm-rate of the transmission can be calculated by multiplying the transmission ratio, the differential ratio, and one-half of the sum of the rpm-rates of the driven wheels. However, if one of the values entering into the calculation is incorrect (e.g., due to a failure of an rpm sensor), the control unit would calculate an incorrect value for the input rpm-rate of the transmission. The error can be further propagated through the power train system, if the input rpm-rate of the transmission is used to determine additional parameters. However, even if the rpm-rates of the wheels have been determined accurately, a control unit in a known state-of-the-art motor vehicle may calculate incorrect values, e.g., if an actual relationship between one or more rpm-rates and one or more calculated values temporarily deviates from the assumed theoretical relationship on which the calculation is based. For example, if the travel speed of the motor vehicle is calculated on the basis of the wheel rpm-rates, the calculated vehicle speed will be inaccurate if any of the wheels are either spinning or locked-up so that they are slipping rather than rolling on the pavement.
Errors in the determination of wheel rpm-rates and/or a faulty calculation of parameters based on the wheel rpm-rates can have a number of adverse effects on the safety and performance of the motor vehicle. For example, the fuel consumption of the vehicle may increase out of the normal range. There is also a risk that certain components of the vehicle may wear excessively or prematurely, and/or that the vehicle may have an increased probability of accidents.
OBJECTS OF THE INVENTION
The present invention therefore has the object of providing a method of operating a motor vehicle that is distinguished from previously known methods in that:
the inventive method will make the motor vehicle safer to operate;
it will in particular improve accuracy and reliability in the detection and processing of operating parameters and control parameters;
it will reduce the fuel consumption of the motor vehicle, while offering at the same time a higher degree of protection against abnormal wear or destruction of components; and
in addition to the foregoing distinctive advantages, the method will be compatible with a cost-effective and uncomplicated manufacturing process of the vehicle.
The invention further has the object of providing a motor vehicle that is equipped to perform the inventive method.
SUMMARY OF THE INVENTION
As a solution to the first of the foregoing objectives, the invention proposes an improved method of operating a motor vehicle that is equipped with a drive source producing a driving torque, a clutch or other torque-transmitting device, a transmission, an arrangement of one or more rpm sensors to detect rpm-rates of wheels and/or axles of the vehicle, and a control unit that regulates the proportion of the driving torque that is transmitted through the torque-transmitting device to the driving axle(s). The method according to the invention has the following steps:
a) detecting the current rpm-rate(s) of one or more driven wheels;
b) evaluating the detected rpm-rate(s) with respect to possible errors that could occur in the detection, transmitting, and processing of the rpm-rate(s);
c) detecting whether a gear shift is about to occur in the transmission; and
d) in case at least one of said possible errors is present, preventing that the gear shift could cause the engine to run at rpm-rates detrimental to the safe operation of the vehicle.
The term “safe operation” as used herein encompasses the functionality of the vehicle and its components, so that the components work together in a trouble-free manner, i.e., without abnormal wear, malfunctions or break-downs, and it also includes fuel economy and occupant safety.
The attribute “detrimental to the safe operation of the vehicle” as used herein means that the safe operation of the vehicle is either negatively affected or that the vehicle becomes totally unsafe to operate.
The invention provides in particular that down-shifts into a lower gear will be blocked in cases where the engine would be forced to run at an impermissibly high rpm-rate as a consequence of the down-shift, which would be detrimental to the safe operation in the sense of the term given above. According to the invention, the “down-shift protection” becomes effective, e.g., in a case where after executing an intended gear change, the resulting rpm-rate of the engine would exceed an applicable limit that may, for example, be set at 50 rpm above an electronically restricted engine rpm-limit.
According to a preferred embodiment of the invention, the method step of preventing excessive rpm-rates of the engine, also referred to as down-shift protection or protection from rpm-rates detrimental to the safe operation of the vehicle, involves the use of at least two different characteristic functional relationships, at least one of which depends on a detected value of an operating parameter of the vehicle.
As an example of the foregoing inventive concept, a first characteristic functional relationship is used to prevent the engine from running at an impermissibly high rpm-rate if a gear is engaged and at the same time the clutch is in an engaged condition, i.e., not slipping . A second characteristic functional relationship is used, on the other hand, if not both of the aforementioned conditions are met at the same time.
For example, if the clutch is completely engaged and not slipping, i.e., if the transmission input shaft and the crankshaft run at the same rpm-rate and if a gear is engaged, the output rpm-rate of the transmission be calculated based on rpm-rate of the engine and vice versa, or the rpm-rate of the engine can also be calculated from the rpm-rates of the driven wheels. The rpm-rate of the engine is obtained by taking one-half of the sum of the two wheel rpm-rates (left and right dri
Henneberger Klaus
Jäger Thomas
Salecker Michael
Schnäbele Jens
Stork Holger
Darby & Darby
LuK Lamellen und Kupplungsbau Beteiligungs KG
Zanelli Michael J.
LandOfFree
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