Mercedes-benz Aktiengesellschaft

Daimler-benz Ag

Walter Klinkner

Heinz Leiber

Manfred Steiner

Erich Schindler

Frank-Werner Mohn

Adam Zomotor

Thomas Wohland

Bernd Knoff

Dean C Karnopp

Dietrich Sahm

Fritz Schmidt

Johannes Clauss

Dieter V Scarpatetti

Robert Haid

A process carries out an automatic braking operation in which, when the return speed of the accelerator pedal exceeds a threshold value and a transfer of the driver's foot from the accelerator pedal to the brake pedal is determined, an automatic braking operation is triggered. During that operation, a brake pressure is generated in the wheel brakes and is terminated when either a defined time has been exceeded since the triggering of the braking operation or when an operation of the brake pedal takes place by the driver. A support of the driver is ensured when operating the brake pedal in critical driving situations and a brake pressure buildup is carried out even before the operation of the brake pedal by the driver. After the automatic braking operation has been triggered, monitoring occurs to determine whether the time derivation of a quantity representing the operation of the brake pedal exceeds a threshold rise value. In such event, exceeding of the threshold rise value must take place within a defined time period after the triggering of the automatic braking operation, whereby the automatic braking operation is continued.

Process for carrying out an automatic braking operation

A method and apparatus for preventing vehicle handling instabilities, in which a vehicle yaw angular velocity required value (.mu..sub.soll) is formed from measured quantities (vehicle velocity, steering wheel angle). The vehicle yaw angular velocity actual value (.mu..sub.ist) is formed from at least one sensor signal, the difference between the yaw angular velocity required value (.mu..sub.soll) and the yaw angular velocity actual value (.mu..sub.ist) is determined by subtracting the yaw angular velocity actual value (.mu..sub.ist) from the yaw angular velocity required value (.mu..sub.soll), and the handling situation or the vehicle yaw behavior to be detected is determined from this difference. The time derivative of the difference is formed to determine whether the vehicle exhibits understeer or oversteer. The slip threshold value (.sigma..sub.soll) is varied in the direction of the value 0 when it is deduced from the detected handling situation that a changed lateral guidance force is required on the wheels of the vehicle driven axle.

Method and apparatus for preventing vehicle handling instabilities

A method detects the driving situation with respect to the yaw behavior of the vehicle, in which a desired value of the vehicle yaw angle rate .mu..sub.des is derived in a computer unit from measured values (such as vehicle speed, steering wheel angle), and at least one sensor signal is supplied to the computer unit from which the actual value of the vehicle yaw angle rate .mu..sub.act is derived. The difference between the desired value of the yaw angle rate .mu..sub.des and the actual value of the yaw angle rate .mu..sub.act is formed in the computer unit. The actual value of the yaw angle rate .mu..sub.act is subtracted from the desired value of the yaw angle rate .mu..sub.des, and at least one output signal is generated in and emitted by the computer unit from this difference. The output signal represents the detected driving situation with respect to the yaw behavior of the vehicle. The magnitude of the time derivative of the difference is used to derive whether there is a tendency towards an increasingly critical driving situation.

Method for detecting driving situation with respect to vehicle yaw

A method and apparatus prevents instabilities in vehicle handling by forming a desired value of the vehicle yaw angle rate .mu..sub.des from measured values (namely, vehicle speed, steering wheel angle), and forming the actual value of the vehicle yaw angle rate .mu..sub.act from at least one sensor signal. The difference between the desired value of the yaw angle rate .mu..sub.des and the actual value of the yaw angle rate .mu..sub.act is formed by subtracting the actual value of the yaw angle rate .mu..sub.act from the desired value of the yaw angle rate .mu..sub.des. At least one output signal is generated and emitted by the computer unit, from this difference. The output signal represents the detected driving situation with respect to the yaw behavior of the vehicle, with the brake pressure of individual wheels of the vehicle being varied as a function of this output signal, and the output signal being generated in the computer unit as a function of a time derivative of the difference. The output signal contains information on whether the vehicle has understeering or oversteering handling. In the case of oversteering handling, the brake pressure is increased for the vehicle front wheel on the outside of the turn; in the case of understeering handling, the brake pressure is increased for the vehicle rear wheel on the inside of the turn.

Apparatus and method for preventing instabilities in vehicle handling

A hydraulic dual-circuit brake system has brake booster with a first output pressure chamber allocated to the front-axle brake circuit I and a second output pressure chamber allocated to the rear-axle brake circuit II. The chambers are movably delimited by master cylinder pistons, to each of which is allocated a position sensor. An electronic control device is provided to process the output signals of the position sensors and to emit control signals for a valve arrangement by which a brake circuit which is poorly bled or leaking is blocked off from its master brake line. The electronic control device includes a comparator, which compares the positions, represented by the two output signals of the positions, represented by the two output signals of the position sensors, of the pistons of the brake booster to one another and produces a signal for the purpose of driving the valve arrangement into its blocking position as soon as the positions of the brake booster piston allocated to the front-axle brake circuit corresponds to a stroke which is greater by more than a threshold value .DELTA.Smax than the stroke of the brake booster piston represented by the position-indicating signal of the brake booster piston allocated to the rear-axle brake circuit. The electronic control device allows this signal to decay again when the difference of the piston strokes falls below a smaller threshold value .DELTA.Smin.

Hydraulic dual-circuit brake system

A hydraulic dual-circuit brake system for a road vehicle with front-axle/rear-axle brake circuit division has a tandem main cylinder as a brake device. The primary output pressure space of the cylinders is associated with the front-axle brake circuit, and the secondary output pressure space of the cylinders is associated with the rear-axle brake circuit. A pressure modulator adjusts the front-axle/rear-axle braking force distribution in the direction of an approach to the, in each case, ideal braking force distribution, as a braking-pressure actuator for the rear-axle brake circuit. The pressure modulator has a drive pressure space, by the charging of which with the output pressure of an auxiliary pressure source under solenoid valve control, a braking pressure which can be coupled into the rear-wheel brakes can be built up in an output pressure space of the pressure modulator. This output pressure space is also connected to the output pressure space of the brake device provided for the rear-axle brake circuit. During normal braking action, the output pressure space of the pressure modulator is blocked off against the output pressure space of the brake device, and the pressure build-up in the rear-axle brake circuit is exclusively effected by the pressure modulator which is driven in the direction of a servo control for which a set point P.sub.s correlated with the braking pressure in the front-axle circuit as ideal or almost ideal value is utilized as a reference variable.

Arranged between hydropneumatic supporting units of a vehicle levelling system is an active bypass and feed system, by means of which hydraulic medium can be displaced between supporting units of different axles or sides of the vehicle, at the same time bypassing a reservoir, in order to counteract pitching and rolling movements of the vehicle.

Hydropneumatic suspension system

The stabilizer of the present invention has a divided torsion bar, the parts of which can be controllably coupled together or separated from one another by a clutch arrangement. The clutch arrangement is switched to the operative condition when a relatively large transverse acceleration of the vehicle occurs or is anticipated. In this arrangement, the value of the transverse acceleration to be expected is preferably determined from the particular steering angle or the particular rate at which the steering angle changes as well as the particular driving speed by means of a computer controlling the clutch arrangement.

Stabilizer for vehicles

Apparatus for controlling a vehicle suspension system includes acceleration sensors mounted on the vehicle for producing electrical signals representative of road surface undulations or irregularities, processing circuitry for processing the sensor signals to produce control signals, and a shock absorber or damper having adjustable damping characteristics. The damper preferably includes two chambers connected by a controllable bypass. One of the chambers becomes smaller during compression of the suspension system, and one becomes smaller during expansion. A controllable throttle and/or valve is provided in the bypass to adjust the damping characteristic of the absorber. The circuitry produces control signals H and w which are representative of the average height of the overall road surface undulations, and a ratio of average heights of long-wave and short-wave undulations, respectively. The circuitry further processes these signals to produce control signals F and P to control the bypass throttle and/or valve, respectively, in accordance with the following relationship:

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Stuttgart, Germany

Walter Klinkner