Data processing: vehicles – navigation – and relative location – Vehicle control – guidance – operation – or indication
Reexamination Certificate
2000-05-18
2001-06-26
Cuchlinski, Jr., William A. (Department: 3661)
Data processing: vehicles, navigation, and relative location
Vehicle control, guidance, operation, or indication
C701S070000, C701S078000, C701S079000, C701S093000, C180S170000, C303S155000, C303S166000
Reexamination Certificate
active
06253123
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a method and a device for stabilizing a vehicle.
BACKGROUND INFORMATION
German Published Patent Application No. 44 16 991 A1 concerns a method and a device for warning truck drivers of the risk (or danger) of rollover (or overturning) when cornering. For this purpose, before the vehicle enters into a turn, the type of vehicle and the condition information relevant for the risk of rollover, such as the weight of the vehicle and the vehicle speed, are determined. Depending on the center of gravity of the vehicle and the radius of the curve, the risk of rollover and the limit (or threshold) speed for that risk are determined. A signal is triggered indicating that the speed must be reduced if the instantaneous traveling speed could cause a rollover risk or the margin of the rollover risk is below a predetermined (or preselected) safety margin. There is a predetermined safety margin of the allowed traveling speed with respect to the traveling speed at the limit of the risk of rollover.
One disadvantage of the System of German Patent Published Patent Application No. 44 16 991 A1 is that when there is a risk of rollover, merely a signal warning the driver is generated instead of having measures implemented automatically or independently of the driver to reduce the speed of the vehicle and thus prevent the risk of rollover. Due to this procedure, there is no longer time to react to an imminent risk of rollover under some circumstances.
German Published Patent Application No. 32 22 149 A1 concerns a device for preventing side rollover of a vehicle. To do so, a static stability is determined as a function of the track and the height of the center of gravity. By multiplying by two different safety factors, two allowed limits are determined from this information. A dynamic instability is determined on the basis of the driving speed of the vehicle, the radius of the curve and the acceleration due to gravity. In two comparisons, this dynamic instability is compared in each case with one of the two allowed limits. If the dynamic instability is greater than the first allowed limit, the gear clutch is released. If the dynamic instability is greater than the second allowed limit, the vehicle's brakes are operated.
Releasing the gear clutch as the first measure to reduce the vehicle speed is a critical intervention or measure because when driving on a gradient, for example, this would not result in a reduction in speed but instead would necessarily increase speed. This risk would not exist with, for example, a straddle loader, the vehicle referred to in German Published Patent Application No. 32 22 149 A1, because such a straddle loader is usually operated on flat terrain.
BRIEF SUMMARY OF THE INVENTION
An object of an exemplary embodiment of the present invention is to provide devices and methods for stabilizing a vehicle, in which not only is the driver warned when a speed quantity is greater than a corresponding reference value, but measures are implemented to stabilize the vehicle. In particular, only measures that would not increase in the risk for the vehicle in any driving situation should be implemented.
Another object of an exemplary embodiment of the present invention is to determine and/or observe various critical situations for the vehicle with the help of a respective limit value for the vehicle speed and to select the critical situation that is the most critical in the given driving situation and to implement the stabilization of the vehicle with respect to this critical situation.
The method according to an exemplary embodiment of the present invention is a method of stabilizing a vehicle. In particular, this should prevent a vehicle from rolling over about a vehicle axis oriented in the longitudinal direction of the vehicle and/or prevent the vehicle from skidding in the transverse direction. For the purpose of illustration, it should be pointed out that there is a risk of rollover if a high transverse acceleration acts on a vehicle at a high coefficient of friction. However, if there is a low coefficient of friction, there is the risk of skidding (or sliding) in the transverse direction.
It should be explained how the phrase “a vehicle axis oriented in the longitudinal direction of the vehicle” should be understood. First, the vehicle axis about which the vehicle may have a tendency to roll over may be the actual longitudinal axis of the vehicle. Second, it may be a vehicle axis which is rotated by a certain angle with respect to the actual longitudinal axis of the vehicle. It does not matter here whether the rotated vehicle axis passes through the center of gravity of the vehicle. The case of the rotated (or offset) vehicle axis should also allow such an orientation of the vehicle axis where the vehicle axis corresponds either to a diagonal axis of the vehicle or to an axis parallel to the diagonal. Furthermore, it should also be pointed out that the phrase “skidding of the vehicle in the transverse direction” also includes spinning of the vehicle.
The method according to an exemplary embodiment of the present invention is advantageously based on a speed comparison. For this purpose, a speed quantity which describes the vehicle speed is determined. In addition, at least two limit values for the vehicle speed are determined. Of these two limit values, one is selected as the reference quantity. In particular, the limit values with the smaller value is selected as the reference quantity. The comparison is performed as a function of the speed quantity and the reference quantity, and measures for stabilizing the vehicle are implemented as a function of this comparison. For the case when the instantaneous speed quantity is greater than the reference quantity, the vehicle speed is reduced at least by retarder measures and/or by engine measures and/or by braking measures on at least one wheel to the extent that the speed quantity resulting from these measures is less than or equal to the reference quantity. The measures in this regard are preferably implemented as a function of the difference between the speed quantity and the reference quantity.
Thus, at least two different critical situations can be detected and/or observed. Selecting one of the limit values as the reference quantity ensures that the vehicle will be stabilized for the situation where there is the greater risk for the vehicle.
Two limit values are preferably determined. A first limit value corresponds to a quantity describing the rollover risk of the vehicle. A second limit value corresponds to a quantity describing the skidding risk of the vehicle, in particular the risk of skidding in the transverse direction. Consequently, the risk of rollover of the vehicle is determined and/or observed with the help of the first limit value, and the risk of skidding or spinning of the vehicle is determined and/or observed with the help of the second limit value.
A mass quantity which describes the mass of the vehicle may be determined. This mass quantity is determined at least as a function of a quantity describing the driving force acting on the vehicle and as a function of quantities describing the wheel rpm. At least one limit value for the vehicle speed is determined as a function of this mass quantity. Since the forces acting on the vehicle in cornering, such as, for example, the centrifugal force, depend on the vehicle mass, the mass quantity enters directly into the determination of the limit value.
Since the second limit value corresponds to a quantity describing the risk of skidding of the vehicle, it is necessary in this regard to determine at least one friction quantity that describes describing the friction conditions between the tires and the road surface prevailing in the given driving situation. It is believed that it is advantageous to determine two friction quantities. A first friction quantity describes the coefficient of friction prevailing instantaneously and a second describes the difference between the coefficients of friction on the right and lef
Faye Ian
Schramm Herbert
Arthur Gertrude
Cuchlinski Jr. William A.
Kenyon & Kenyon
Robert & Bosch GmbH
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