Measuring and testing – Brake testing – Vehicle installation
Reexamination Certificate
1999-12-28
2002-09-17
McCall, Eric S. (Department: 2855)
Measuring and testing
Brake testing
Vehicle installation
C340S431000, C701S083000
Reexamination Certificate
active
06450019
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to an apparatus and a method for stabilizing a vehicle combination made up of a tractor vehicle and a trailer or semitrailer.
BACKGROUND INFORMATION
German Published Patent Application No. 25 47 487 describes an apparatus for stabilizing a vehicle that comprises a leading element and a towed element. The towed element is joined via a linkage to the leading element. The apparatus has a transducer for sampling the inflection angle between the leading element and towed element. A transducer is also provided to sense the steering angle. The apparatus comprises an analysis circuit to which the signals of both transducers are conveyed and which generates output signals if the inflection angle exceeds specific angular variables that depend on the steering angle. The specific angular variables correspond to the inflection angles determined as a function of the steering angle and permissible in the respective driving situation. In addition, the apparatus provides for a device, for automatically applying brake pressure to at least one axle of the towed element, which is actuated by the output signals of the analysis circuit. By way of the braking action, the operation described above causes the vehicle to stretch out, thus decreasing the instantaneous inflection angle.
SUMMARY OF THE INVENTION
An object of the present invention is to improve existing apparatuses and methods for stabilizing a vehicle combination.
Since their introduction, the use of brake slip control systems to prevent accidents in critical longitudinally dynamic driving situations has become more and more widespread. Such brake slip control systems are available both for passenger cars and for commercial vehicles. For quite some time, driving safety for passenger cars has been additionally improved with a so-called vehicle dynamics control system. A vehicle dynamics control system of this kind is used to control the yaw rate of the vehicle. Vehicle dynamics control systems not only offer the driver improved basic functionality in terms of brake slip and drive slip control, but also provide him or her with active assistance in critical transversely dynamic situations. Vehicle stability is thereby improved in all operating situations, i.e. in the full and partial braking range, when coasting, under power, and in response to load changes. The vehicle dynamics control system engages as soon as the vehicle-dynamics limit region is reached. In passenger cars, the vehicle dynamics control system reduces the risk of a spin even in extreme steering maneuvers, and allows the vehicle to be controlled safely.
The advantages of a vehicle dynamics control system are also to be made available for commercial vehicles. For commercial vehicles, however, the requirements in terms of stability are not limited simply to the spin characteristics of a single vehicle element; instead, inflection of the members of a multi-part vehicle must also be taken into account. The apparatus according to the present invention is an apparatus for stabilizing a vehicle combination comprising a tractor vehicle and a trailer or semitrailer. Because of its widespread use for road transport of goods, and the particular problems of tractor-trailer units, in the exemplary embodiment the apparatus according to the present invention is presented for a vehicle combination comprising a tractor vehicle and a semitrailer. Irrespective of this, the apparatus according to the present invention can also be used for a vehicle combination that comprises a tractor vehicle and a trailer, in particular a drawbar trailer. In vehicle combinations, a hazardous situation occurs as soon as the inflection angle between tractor vehicle and semitrailer or trailer becomes too great.
The apparatus according to the present invention contains a first determination arrangement which is used to determine an inflection angle variable that describes the angle between an axis oriented in the longitudinal direction of the tractor vehicle, in particular the longitudinal axis of the tractor vehicle, and an axis oriented in the longitudinal direction of the trailer or semitrailer, in particular the longitudinal axis of the trailer or semitrailer. The apparatus also contains a processing arrangement with which a comparison is made as a function of the inflection angle variable and a comparison variable. The apparatus also has a first actuator arrangement which is associated with the trailer or semitrailer and with which a brake pressure can be established at at least one wheel of the trailer or semitrailer. These first actuator arrangement is actuated at least as a function of the comparison performed with the processing arrangement.
According to the present invention, the apparatus contains a second determination arrangement with which the comparison variable is determined as a function of a velocity variable that describes the velocity of the tractor vehicle, and/or as a function of whether stability interventions are being performed for the tractor vehicle.
The determination according to the present invention of the comparison variable as a function of the velocity variable is made because the velocity of the vehicle combination influences the stability of the vehicle combination to a considerable degree. If the vehicle combination has a low velocity (as is the case, for example, during a parking maneuver), a large comparison variable can be permitted for the inflection angle. Because of the low kinetic energy of the semitrailer, an increase in the inflection angle - such as might occur, for example, by possible pushing of the semitrailer during a braking operation - and thus instability of the vehicle combination, are not to be expected. If, on the other hand, the velocity of the vehicle combination is high (as is the case, for example, during highway driving), a comparison variable that is smaller than in the case of a parking maneuver must be defined for the inflection angle. If too great an inflection angle were permitted while traveling at high velocity, a transverse dynamic influence on the semitrailer, because of its high kinetic energy, could result in an uncontrolled increase in the inflection angle and thus in jackknifing of the vehicle combination. Against this background, it is clear that a preset comparison variable that has a high value, such as is necessary, for example, for a parking maneuver, cannot be used. Too great a comparison variable would result in poor stability at higher vehicle velocities, since potential instabilities would be detected too late, and thus the first actuator arrangement would be actuated too late.
The reason why the comparison variable is determined as a function of whether stability interventions are being performed for the tractor vehicle is that if stability interventions are being performed for the tractor vehicle, instability of the vehicle combination may be expected. Since stability interventions on the tractor vehicle result, inter alia, in a reduction in the velocity of the tractor vehicle, the inflection angle allowed should not be too great in such a case, since in such cases it could result in an increase in the inflection angle and thus in instability of the vehicle combination.
The aforementioned stability interventions for the tractor vehicle are advantageously those that are performed at least as a function of a variable describing the transverse dynamics of the tractor vehicle, in particular a variable describing the yaw rate and/or the transverse acceleration of the tractor vehicle. These variables are usually controlled in the vehicle dynamics control systems mentioned earlier. Alternatively or additionally, the stability interventions for the tractor vehicle are also performed as a function of wheel behavior variables which describe the wheel behavior of the wheels of the tractor vehicle or semitrailer. The wheel behavior variables are, for example, wheel rotation speed variables or slip variables.
In order to implement the stability interventions that are performed for the tract
Faye Ian
Kühnle Uwe
Leimbach Klaus-Dieter
Wetzel Gabriel
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