Interrelated power delivery controls – including engine control – Transmission control – Engine controlled by transmission
Reexamination Certificate
2001-11-02
2004-02-10
Estremsky, Sherry (Department: 3681)
Interrelated power delivery controls, including engine control
Transmission control
Engine controlled by transmission
C180S197000, C701S084000, C701S085000, C701S086000
Reexamination Certificate
active
06689015
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a method for influencing the propulsive power of a motor vehicle driven by a drive motor.
BACKGROUND INFORMATION
Methods and apparatuses for influencing the propulsive power of a motor vehicle are described in the existing art.
German Patent No. 195 40 067 A1 discusses a method for controlling the driving of multiple separately driven vehicle wheels of a motor vehicle. Upon the occurrence of drive slip at one of the drive wheels of the motor vehicle, the traction torque absent as a result of slip is transferred, up to a certain proportion, to the other drive wheel or wheels. This ensures that excessive drive torque is not transferred to the drive wheel that is still gripping, since this would create increased drive slip at that wheel as well. In particular, the drive slip of the drive wheel that is still gripping better is regulated to a drive slip setpoint that is set to a minimum setpoint which still ensures sufficient traction in every case.
In order to allow driving with an increased drive slip in specific situations, in such situations the drive slip setpoint is continuously elevated. To detect these situations, the position of an accelerator pedal of the motor vehicle is evaluated. If, in a situation with an increased tendency toward drive slip, the driver does not let off on the accelerator pedal but rather maintains its position or even presses it even further, this is interpreted as a desire to establish a greater drive slip at the drive wheels. The drive slip setpoints can be defined uniformly for all drive wheels, or for individual wheels.
With the known method, the drive slip of a drive wheel of the motor vehicle is employed as the wheel variable. A drive slip setpoint is ascertained, as the intervention variable, for one or more drive wheels of the motor vehicle.
A further example that may be cited of a method and an apparatus for influencing the propulsive power of a motor vehicle is SAE Paper 870 337, “ASR Traction Control—A Logical Extension of ABS.” With a drive slip control system of this kind (abbreviated ASR), the propulsive power of a motor vehicle is adjusted as a function of the wheel slip ascertained for the drive wheels. The propulsive power is adjusted in such a way that the slip of the driven wheels does not exceed a threshold value defined for the drive wheels. The result of this measure is to ensure, in the drive context, stability of the vehicle as well as sufficient traction.
The article “FDR—The Bosch vehicle dynamics control system” [FDR—Die Fahrdynamikregelung von Bosch], published in Automobiltechnische Zeitschrift (ATZ) 96, 1994, Vol. 11, pages
674-689, discloses a slip control system in which the yaw rate of the motor vehicle is controlled. For this purpose, the deviation between a setpoint for the yaw rate and a measured value for the yaw rate is ascertained. As a function of this system deviation, reference slip values are ascertained and are established with the aid of braking interventions and engine interventions. This type of slip control system has a higher-level controller for the yaw rate, and lower-level controllers for a brake slip and a drive slip.
In addition to conventional drive slip control as described in SAE Paper 870 337, in which the wheel slip occurring at the drive wheels is compared to threshold values, there is known from German Patent No. 199 13 825 a method for adjusting the propulsive power in which an intervention variable is ascertained on the basis of characteristics diagrams. Provision is made for two characteristics diagrams. With a first characteristics diagram, a first value for the intervention variable is created as a function of a gradient of the slip and a reference speed of the motor vehicle. With a second characteristics diagram, a second value for the intervention variable is created as a function of a slip and the reference speed of the motor vehicle. The intervention variable itself is then derived from the two values, for example by addition. The propulsive power of the motor vehicle is adjusted as a function of the intervention value.
Also known, from German Patent No. 198 44 912, is an apparatus with which an intervention variable is ascertained as a function of a transverse acceleration variable and a variable that describes the behavior over time of the transverse acceleration variable. The intervention variable is ascertained on the basis of two characteristics diagrams: a first characteristics diagram for the transverse acceleration, and a second characteristics diagram for the variable that describes the behavior over time of the transverse acceleration. To influence the propulsive power, interventions are performed on the drive motor of the motor vehicle as a function of the intervention variable. In the context of the methods and apparatuses discussed above for influencing the propulsive power of a motor vehicle, there are situations with regard to drive slip in which a greater propulsive power or elevated drive slip is desired.
One example that may be cited as a situation in which a greater propulsive power is desired is driving on an unconsolidated surface, for example on gravel or in deep snow, or operating the motor vehicle with snow chains, or off-road driving. When driving in deep snow, it may happen that the wheels of the motor vehicle “dig in” and the vehicle comes to a stop. When the driver then attempts to start from rest in such a situation, this will not be possible. Since the wheels have dug into the deep snow, they exhibit a great deal of drive slip when attempting to start from rest. An ASR detects the slip and brakes the driven wheels. The driver thus cannot generate sufficient propulsive power to allow him or her to drive the motor vehicle out of its “dug-in” position.
For this reason, it is known in the context of ASR systems to arrange on the instrument panel a switch that can be actuated by the driver. Actuation of the switch raises the slip thresholds of the ASR system. The result is that when the switch is pressed, an increased propulsive power can be established. This therefore makes it possible for the driver of a motor vehicle that is “dug in” in deep snow to drive the vehicle back out of the deep snow by “rocking” it free.
A further situation in which greater propulsive power of the motor vehicle is desirable is, for example, a sporty driving style. As a result of the interventions of a slip control system or an apparatus such as the one known from German Patent No. 198 44 912, a sporty driver can feel too limited. The slip control system or the aforementioned apparatus does ensure sufficient lateral stability for the vehicle in curves, but the result is that a driver cannot negotiate a curve with the desired propulsive power that he or she has selected, since because the intervention variable is prepared as a function of the transverse acceleration and the change over time in the transverse acceleration, the intervention variable—and with it the propulsive power as well—is limited. The limitation is applied in such a way that in the context of the existing transverse acceleration and the change over time in the transverse acceleration, and allowing for a certain safety factor, the driving behavior of the motor vehicle is stable with a very high probability. For a sporty driver, however, this can constitute a limitation.
The utilization, known from the existing art, of a switch to lower the drive slip thresholds also entails safety risks. If the driver forgets to release the switch again, and if the motor vehicle is no longer in one of the situations described (e.g. in deep snow), then in other situations in which assistance by a slip control system (e.g. a drive slip control system or yaw rate control system) would be necessary, the stabilization of vehicle dynamics is absent or insufficient.
It is therefore an object of the present invention, in the context of a motor vehicle with a slip control system, to create an easily manipulated, safe, and reliable capability for automatically detecting
Schmitt Johannes
Weiss Tobias
Estremsky Sherry
Kenyon & Kenyon
Robert & Bosch GmbH
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