DE102012222490B4 - Method for increasing the driving stability of a vehicle - Google Patents

Abstract

Method for increasing the driving stability of a vehicle, which is equipped with wheel speed sensors on all wheels and a braking system that allows at least a wheel-specific reduction in the braking force, characterized in that the braking system allows a driver-independent wheel-specific buildup of braking force, and upon detection of a sudden loss of tire pressure Yaw moment compensation takes place through a driver-independent build-up of braking force, with a driver-independent build-up of braking force taking place on the wheel opposite the defective wheel on the same axle immediately after detection of a sudden loss of tire pressure for yawing moment compensation.

Description

The invention relates to a method according to the preamble of claim 1, its use in a motor vehicle and an electronic control unit according to claim 12.

If, while driving a vehicle, there is a sudden loss of pressure in a tire, especially on the front axle, the rolling resistance of the affected wheel is suddenly increased, resulting in an unwanted and unexpected torque around the vertical axis of the vehicle, which can lead to a sideways pull or, in the worst case, to a wheel pull can lead to complete uncontrollability of the vehicle.

From the DE 101 29 737 A1 a method for detecting tire pressure loss is known. In particular, the free-rolling driving condition is particularly taken into account. The method comprises two algorithms, with a first algorithm calculating a first set of reference variables and a second algorithm calculating a second set of reference variables. To detect the pressure loss, compliance with the limit values of the reference variables is checked.

From the DE 10 2011 121 496 A1 an electronic device of a vehicle system is known to have wheel speed detection means for determining the wheel speed of a vehicle wheel and a processing unit for determining a wheel acceleration of this wheel. A vehicle acceleration is determined as a first reference signal of the first wheel acceleration and the vehicle acceleration.

The DE 199 61 681 A1 now discloses another method for detecting pressure loss in a tire, which works as a function of a driving dynamics variable. These variables are checked for the presence of certain conditions with regard to their values or the course of time.

From the U.S. 5,934,768 A a brake control device is known, with a control device for controlling brake actuators on each wheel of the vehicle, and a device for detecting a loss of pressure in any tire of the vehicle. When the air pressure in a tire falls below a predetermined level, the brake actuator on the wheel laterally opposite the deflated tire is actuated. Too low an air pressure is determined by comparing a measured transverse dynamic variable with a calculated one. For example, a target wheel speed difference between the right and left front wheel is calculated based on the steering wheel angle and compared to the measured actual wheel speed difference. If the deviation is outside a tolerance band, a tire pressure loss is detected.

The U.S. 5,696,681 A discloses a method for controlling the driving dynamics of a motor vehicle, in which a control unit triggers braking interventions on selected wheels when a sudden tire burst is detected. A burst tire is detected, for example, using pressure sensors. A target trajectory is then calculated based on a target yaw rate and the difference between the actual trajectory and the target trajectory is regulated by braking interventions on the front and rear wheels on the left or right side.

Furthermore, driving dynamics control systems are known under the term “Electronic Stability Control” (ESC), in which a target yaw rate of the vehicle is calculated from a measured steering angle and other vehicle data and compared with an actual yaw rate measured by a sensor. By building up braking torque independently of the driver on one or more vehicle wheels, in particular by activating a hydraulic pump and actuating solenoid valves in the case of hydraulic braking systems, a yaw moment is applied in a targeted manner, which reduces the difference between the desired and actual yaw rate. Such a system for driving stability control is, for example, from EP 0 792 229 B1 known.

In order to avoid control errors, it is necessary when detecting a tire burst from the driving dynamics parameters of the vehicle to trigger a braking intervention only when there has been a significant deviation from the target behavior for at least a predetermined period of time. Thus, even with successful regulation, the vehicle can be offset or a potentially dangerous course deviation can occur. In addition, the driver can be frightened and reflexively make violent steering or braking interventions, which further jeopardize driving safety.

It is therefore the object of the present invention to avoid or to correct as quickly as possible a destabilization of the affected vehicle caused by a sudden pressure loss or tire defect. It is also desirable to avoid instabilities caused by violent driver reaction.

According to the invention, this object is achieved by a method according to claim 1 .

So there is a method for increasing the driving stability of a vehicle is provided, which is equipped with wheel speed sensors on all wheels and a braking system that at least allows a wheel-specific reduction of the braking force. According to the invention, when a sudden loss of tire pressure is detected, in particular a tire bursting, the yaw moment is reduced during braking by the driver and/or the yaw moment is compensated for by a driver-independent build-up of braking force. Corrective braking intervention takes place immediately when a loss of tire pressure is detected, so that a yaw moment caused by the burst tire is immediately weakened or actively compensated for, which largely prevents the vehicle from clearly deviating from the course and/or damaging the driver, which could lead to an overreaction when countersteering .

Preferably, when the driver detects a sudden loss of tire pressure during braking, the yaw moment is weakened by limiting or reducing the braking force requested or applied by the driver at the defective wheel. Since the burst tire brakes harder and would therefore produce a disruptive yawing moment, the brake pressure applied by the driver is reduced on the wheel on which the burst tire is located; the disruptive yawing moment is weakened or limited. Thus, even vehicles equipped only with an anti-lock braking system can be kept under control for the driver in the event of a tire bursting.

In a vehicle with a braking system that allows a driver-independent, wheel-specific build-up of braking force and, in particular, includes vehicle dynamics control, when a sudden loss of tire pressure is detected for yaw moment compensation, a driver-independent build-up of braking force occurs on the wheel that is opposite the defective wheel on the same axle. Thus, even if the driver does not brake, a yawing moment caused by the burst tire can be compensated and a risk to driving safety can be avoided. The yaw moment compensation can in particular be carried out independently of braking by the driver, i.e. also in addition to a yaw moment weakening.

When a tire pressure loss is detected, a first component of the braking force is particularly preferably built up as a control component, with the amount of the first component depending on the yaw acceleration present when the sudden tire pressure loss is detected and/or the vehicle speed and/or an estimated coefficient of friction and/or a brake actuation the driver is chosen.

This pre-control enables immediate compensation of the yaw moment caused by the tire bursting, since no previously required exceeding of control thresholds and thus a delayed reaction caused by the vehicle inertia delays the braking intervention. By taking suitable parameters into account, the braking intervention can be dimensioned appropriately.

It is particularly advantageous if at least a further portion of the braking force built up (or the entire braking force) is determined as a control portion based on a deviation between a reference yaw rate and a measured yaw rate, with only the control portion of the braking force being built up in particular after a predetermined period of time has elapsed . Regulation of the yaw rate difference allows for a long-term and comfortable minimization of disruptive yaw moments that occur. The reduction in the pre-steer component also results in the driver being slowly prompted to apply a compensating steering angle in order to stay on the desired course. This has the advantage that the driver is informed of the problem of the vehicle pulling sideways and is thus made aware of the driving dynamics problem.

When a sudden tire pressure loss is detected, a predetermined braking force difference between the defective wheel and the opposite wheel on the same axle is expediently set, which preferably has a predetermined fixed amount. Based on parameters determined at the time of the sudden loss of tire pressure, a disruptive yaw moment that occurs can be determined at least approximately even without a yaw rate sensor and compensated or at least mitigated by a suitable braking force difference.

After a tire pressure loss is detected, the gradient of a brake actuation by the driver is preferably limited, the pressure build-up in the wheel opposite the defective wheel on the same axle taking place in accordance with a brake slip control of the defective wheel. The burst tire causes a vehicle behavior that is similar to braking with a different coefficient of friction on each side (µ-split situation), i.e. the different transmittable braking forces cause an ever stronger yawing moment during braking. This is weakened or built up with a delay, giving the driver enough time for controlled countersteering.

It is expedient if, for at least partial yaw moment compensation, a steering torque is introduced into the steering train, which preferably has a predetermined fixed amount which is particularly dependent on the at Detection of the tire burst present yaw acceleration and / or vehicle speed and / or an estimated coefficient of friction is selected. Since inexpensive vehicles are also increasingly equipped with electric power steering, this can be used to build up a yaw moment, which can indicate the appropriate countersteering direction to the driver and can support him in countersteering.

Tire pressure loss detection is preferably activated when the vehicle is driving faster than a minimum speed and/or the steering wheel speed falls below a specified steering threshold value and/or the engine torque is within a specified engine tolerance band and/or the wheel speed of all wheels is within a specified wheel speed tolerance band for a second specified period of time lies. Especially when driving on a highway, a burst tire can cause serious accidents because of the high vehicle speeds. At the same time, there are often well-defined driving conditions that enable reliable detection of a sudden loss of tire pressure or a tire burst, also from wheel speed information.

A sudden loss of tire pressure is particularly preferably detected when the wheel speed of a rear wheel drops suddenly or the wheel speed of a front wheel drops suddenly without the corresponding rear wheel showing a corresponding behavior and/or the sudden loss of tire pressure is detected when a pressure sensor assigned to the wheel shows a sudden decrease in pressure. If there are pressure sensors that allow an adequate pressure measurement, a sudden jump in the measured pressure or an error message from the pressure sensor can be taken into account as the sole condition or additionally when detecting a tire burst. A sudden drop in the wheel speed is understood to mean a decrease in the measured wheel speed between two consecutive measurements that exceeds a predetermined step threshold value. In addition, it can be provided to check an approximately constant wheel speed before the jump as an additional condition. Accordingly, an abruptly reduced pressure can be recognized when, after several almost constant measured pressure values, a change in the pressure that exceeds a predetermined threshold value is recognized. In order to avoid incorrect identification, a subsequent pressure or wheel speed measurement value can also be taken into account if the measurement frequency of the respective sensor is sufficient. A sudden loss of tire pressure can be identified from wheel speed information if a wheel shows a sudden change in rotational behavior that was not caused by a change in the coefficient of friction (since the corresponding front or rear wheel shows no change in rotational behavior).

The invention also relates to the use of a method according to the invention in a motor vehicle which is driven by an internal combustion engine and/or one or more electric motors.

The invention also relates to an electronic control unit for a brake system, with an interface for at least two wheel speed sensors, comprising or connected to a hydraulic unit with at least one solenoid valve, which has a computing unit that executes a method according to the invention. For example, it can be a core-redundant microcontroller.

Further preferred embodiments result from the subclaims and the following description of an embodiment with reference to figures.

• 1a eine schematische Darstellung eines Kraftfahrzeugs,
• 1b einen schematischen Aufbau eines hydraulischen Bremssystems,
• 2 ein Ausführungsbeispiel zur Giermomentenabschwächung, und
• 3 ein Ausführungsbeispiel zur Giermomentenkompensation.

Show it

• 1a a schematic representation of a motor vehicle,
• 1b a schematic structure of a hydraulic brake system,
• 2 an embodiment for yaw moment mitigation, and
• 3 an embodiment for yaw moment compensation.

1a shows a schematic representation of a motor vehicle 1, which is suitable for carrying out a method according to the invention with both a yaw moment reduction and a yaw moment compensation. It has a drive motor 2, which drives at least part of the wheels of the vehicle, in particular the front wheels, a steering wheel 3, a brake pedal 4, which is connected to a tandem master cylinder (THZ) 13, and four individually controllable wheel brakes 10a-10d. In addition to hydraulic friction brakes, electromechanically actuated friction brakes can also be used as wheel brakes on one, several or all wheels. The vehicle can also have an electric drive, in which case, in particular, the braking torque on a wheel can be generated at least partially by an electric machine operated as a generator, which is assigned only to this wheel.

A steering angle sensor 12, four wheel speed sensors 9a - 9d, a lateral acceleration sensor 5, a yaw rate sensor 6 and at least one pressure sensor 14 for the brake pressure generated by the brake pedal are present in a vehicle equipped with a vehicle dynamics control system for detecting driving dynamics states. The pressure sensor 14 can also be replaced by a pedal travel or pedal force sensor if the auxiliary pressure source is arranged in such a way that a brake pressure built up by the driver cannot be distinguished from that of the auxiliary pressure source, or an electromechanical brake actuator with a known relationship between the pedal position and the braking torque is used. If vehicle 1 only has anti-lock braking or brake slip control, steering angle sensor 12, lateral acceleration sensor 5, yaw rate sensor 6 and, if necessary, pressure sensor 14 can also be dispensed with, since only wheel speed sensors 9a, 9b, 9c, 9d are required for brake slip control.

The electronic control unit (ECU) 7 receives the data from the various sensors and controls the hydraulic unit (HCU) 8. In addition, the drive torque currently generated by the drive motor 2 and the torque desired by the driver are determined. These can also be indirectly determined variables, which are derived, for example, from an engine map and are transmitted to the electronic control unit 7 via an interface 11 of a vehicle data bus, such as CAN, from the engine control unit (not shown).

The driving behavior of the motor vehicle 1 is significantly influenced by the chassis design, with wheel load distribution, elasticity of the wheel suspension and tire properties determining the self-steering behavior, among other things. In certain driving situations, which are characterized by a predetermined, desired cornering radius and the coefficient of friction between the tires and the road, there can be a loss of driving stability, with the steering behavior desired by the driver not being able to be achieved with the given chassis design. With the sensors present in vehicle dynamics control, the driver's request can be recognized and the realization by the vehicle can be checked.

1b shows a schematic structure of a hydraulic brake system in which the brake pedal 4 actuated by the driver acts with or without auxiliary power on a tandem master brake cylinder 13, which causes a pressure build-up in a first brake circuit I and a second brake circuit II. Two wheel brakes 10 are arranged in a brake circuit; In addition to the black and white split shown here, in which the wheel brakes 10a, 10b on the front axle are assigned to the first brake circuit I and the wheel brakes 10c, 10d on the rear axle are assigned to the second brake circuit II, a diagonal split is also possible, in which one wheel brake is assigned to the Front axle and a wheel brake of the rear axle are assigned to a brake circuit. The pressure built up in master brake cylinder 13 is measured by means of pressure sensor 14 .

The brake pressures in the wheel brakes can be modulated via solenoid valves, which are controlled by the electronic control unit 7 (not shown). Each wheel brake 10 is assigned an inlet valve 24 that is open when deenergized and an outlet valve 25 that is closed when deenergized. During brake slip control, for example, the pressure in wheel brake 10a can be reduced by closing inlet valve 24a to prevent the pressure from increasing further as a result of pedal actuation by the driver, and opening outlet valve 25a to drain brake fluid into a low-pressure accumulator 22. When the low-pressure accumulator 22 is filled, the return pump 20 driven by an electric motor 19 is activated, the intake side of which is connected to the low-pressure accumulator 22 and the outlet side of which is connected to the master brake cylinder 13 . Corresponding to the procedure described here in brake circuit I, the pressure in one or both wheel brakes 10c, 10d can also be reduced in brake circuit II, which in principle has the same structure, if the inlet valve or valves 24c, 24d are closed and the outlet valve or valves 25c, 25d open Derive brake fluid in the low storage 23. Return pump 21, which is expediently also driven by electric motor 19, can be activated in order to empty low-pressure accumulator 23.

Vehicles that are equipped with vehicle dynamics control also have a normally open separating valve 16/18 in each brake circuit I/II, which is arranged between the outlet of the return pump and the master brake cylinder, and a normally closed changeover valve 15/17, which is located between the inlet of the return pump and master brake cylinder is arranged. This enables a driver-independent pressure build-up in one or both wheel brakes of a brake circuit. If, for example, a braking force is to be built up in wheel brake 10a, isolating valve 16 is closed, switching valve 15 is opened and return pump 20 is activated. In order to prevent pressure also being built up in wheel brake 10b, inlet valve 25b can be closed before the pump is activated.

• Mittels eine Drucksensors oder über ein Druckmodell wird der Druck ermittelt, den der Fahrer im Hauptbremszylinder als Vordruck einstellt. Beispielsweise kann der Druck gemäß $${\text{p}}_{\text{driver}}=\text{f}\left(\text{Fahrzeugverz}\ddot{\text{o}}\text{gerung}\right)$$
  
  berechnet werden, wobei die Fahrzeugverzögerung zweckmäßigerweise anhand der Raddrehzahlen der nicht vom Reifenschaden betroffenen Räder ermittelt wird.

2 shows an exemplary embodiment for reducing the yawing moment, with the time profile of the wheel speed in the upper diagram v, ie the wheel speeds V _front,left of the left front wheel and V _front,right of the right front wheel are shown over time t. The diagram below shows the brake pressure p over time, with the pressure p _driver in the master brake cylinder and the pressures p _front,left in the wheel brake of the left front wheel and p _front,right in the wheel brake of the right front wheel being shown. At time t0, tire damage occurs on the left front wheel, whereupon the driver brakes at time t1. The following measures are then taken:

• A pressure sensor or a pressure model is used to determine the pressure that the driver sets in the master brake cylinder as the admission pressure. For example, the pressure according to $${\text{p}}_{\text{driver}}=\text{f}\left(\text{vehicle registration}\ddot{\text{O}}\text{struggle}\right)$$
  
  are calculated, the vehicle deceleration being expediently determined using the wheel speeds of the wheels not affected by tire damage.

As soon as driver admission pressure p _driver has reached a first predetermined threshold value, ie at time t2, inlet valve 24a on the left front wheel (with the tire damage) is closed. If the driver's admission pressure reaches a second predetermined threshold value, ie at time t3, which is higher than the first threshold value by a predetermined pressure difference ΔP, inlet valve 24b of the right front wheel (with an intact tire) is also closed. The pressure difference compensates for a disruptive yawing moment, which occurs when the defective wheel generates a stronger braking force with the same braking pressure due to the increased rolling resistance. A further pressure build-up in the wheel brakes on the front axle is only pulsed.

Due to a reduced adhesion between the defective tire and the road surface, the defective wheel tends to lock even after a small pressure build-up. It is therefore advantageous to carry out brake slip control on the wheel in question with a sensitively switched control threshold or a reduced setpoint slip. At time t ₄ the control threshold is exceeded at the left front wheel and a known ABS control is started.

• • Erfolgt ein Druckabbau am defekten Rad, so erfolgt auch ein vorzugsweise um einen vorgegebenen Faktor bzw. eine vorgegebene Differenz verringerter Druckabbau am intakten Rad, wie im Diagramm kurz nach t₄ dargestellt ist.
• • Ein Druckaufbau am intakten Rad wird nur dann vorgenommem, wenn zeitgleich auch am defekten Rad Druck aufgebaut werden kann bzw. eine vorgegebene Wartezeit verstrichen ist.
• • Wenn das defekte Rad gerade instabil ist, sich also in einer Druckabbauphase mit anschließendem Druckhalten befindet, wird ein Druckaufbau am intakten Rad unterlassen.

In principle, the intact right front wheel could brake significantly more than the defective one if its own locking pressure were adjusted. However, this would cause strong yaw moments that could cause the vehicle to skid. The pressure build-up gradient of the right front wheel is limited in order to keep the yaw moments caused by the asymmetrical brake force distribution between the left and right front wheels low. That is, a pressure increase up to the own locking pressure level is only carried out very moderately on the right front wheel:

• If there is a pressure reduction on the defective wheel, then there is also a pressure reduction on the intact wheel, which is preferably reduced by a predetermined factor or a predetermined difference, as shown in the diagram shortly after t ₄ .
• • Pressure is only built up on the intact wheel if pressure can also be built up on the defective wheel at the same time or a specified waiting time has elapsed.
• • If the defective wheel is currently unstable, ie is in a pressure reduction phase with subsequent pressure maintenance, pressure is not built up on the intact wheel.

An existing anti-lock brake control is accordingly modified as an alternative or in addition to an active pressure build-up, in that a yaw moment reduction is preferably carried out when the driver applies the brake before, during or after a tire pressure loss. In this way, vehicles that are only equipped with an anti-lock braking system or brake slip control (ABS only) can be optimally conditioned and kept under control for the driver in the event of a tire bursting.

If the braking system of the vehicle allows braking force to be built up independently of the driver, active yaw moment compensation is preferably also provided. To avoid vehicle instability due to a burst tire, it is advantageous to actively build up pressure on the other wheel on the same axle immediately after recognizing the situation.

According to a particularly preferred embodiment of the invention, it is proposed here that the level of the pressure build-up be dependent on one or more of the following parameters. A first parameter is the vehicle speed, since the braking torque that occurs as a result of the loss of tire pressure depends on the vehicle speed. A second parameter is the yaw jerk that occurs immediately after the tire bursts, or the yaw acceleration that occurs. An estimated adhesion coefficient between the road surface and the tires is preferably taken into account as the third parameter.

Since today's ESC systems are only activated in the event of relatively high deviations between the measured yaw rate and the target yaw rate, which is largely based on the steering angle, which occur in particular over a longer period of time, a vehicle based on the prior art would already have a value that deviates significantly from the driver's specification Show yaw reaction before yaw moment control occurs.

The active or driver-independent pressure build-up expediently takes place at least initially in the form of a pilot control, with a constant braking torque or a braking torque adapted using the parameters mentioned above being built up in a time interval at which state-of-the-art driving dynamics control would not yet intervene due to the lack of control deviation.

According to a particularly preferred embodiment of the invention, this pre-control component is slowly reduced towards zero over the course of a defined time of, for example, 2 seconds, so that the further control is taken over by the ESC.

The pre-control thus changes to an ESC control based on proven sensors (yaw rate sensor, steering wheel angle sensor, lateral acceleration sensor, wheel speed sensors). In order to make this transition as homogeneous as possible, it is particularly preferred to reduce the control thresholds (e.g. for the difference between the desired and actual yaw rate) in the ESC when the tire burst event has been detected.

In the following, a vehicle with a hydraulic brake system as in 1 assumed, in which a driver-independent pressure build-up on one or more individual wheels is possible by activating a hydraulic pump and solenoid valves are suitably controlled. In principle, however, the method according to the invention can also be carried out with an electromechanical brake system.

3 shows an exemplary embodiment for yaw moment compensation, the upper diagram showing the time profiles of the measured yaw rate Ψ _act , the reference yaw rate Ψ _ref calculated in a vehicle model and the steering angle δ _driver specified by the driver. The diagram below shows an amplification factor K and the brake pressure P _front,right, which is proportional to the braking force, over time t.

At time t0 the left front tire bursts and is reliably detected. As a result of the tire bursting, an undesirable vehicle yaw rate Ψ̇ _act builds up in the left-hand direction of rotation. A state-of-the-art driving dynamics control system would only then request a compensating yaw moment by building up braking torque if the yaw rate deviation exceeds a predetermined activation threshold ΔΨ̇ _thr , ie the behavior of the vehicle differs significantly from the desired one. In a method according to the invention, an active pressure build-up in the wheel brake or a build-up of braking force by the respective brake actuator is started by pilot control, as a result of which the brake linings are applied to the friction surface. This overcoming of the clearance is complete at time t ₁ .

In order for a driving dynamics control ESC to start as early as possible with a stabilizing pressure build-up for the individual wheels, time filters that delay the onset are deactivated when a tire burst is detected and the activation threshold ΔΨ̇ _tnr of the ESC is reduced to a very small value of in particular l°/s. In the example shown, the driver reacts to the slight turning of the vehicle to the left (positive yaw rate) with a steering angle specification δ _driver to the right (negative values), which also results in a negative reference yaw rate Ψ̇ _ref .

Based on the control deviation between the measured actual yaw rate and the calculated reference yaw rate, the ESC controller, for example a pure proportional controller (P controller), determines a brake request or a brake pressure P _{front,right,req} to be built up in the wheel brake of the right front wheel: $$P_{f\mathrm{right}Ont,\mathrm{right}iGHt,\mathrm{right}eq}=K\cdot \left({\dot{\Psi }}_{act}-{\dot{\Psi }}_{\mathrm{right}ef}\right)$$

The amplification factor K is expediently set to a high starting value Kmax when the control is entered. This means that the brakes are applied early, before the system deviation has caused the vehicle to move significantly. It is advantageous if the absolute value of K is reduced to a normal value K _normal from a point in time t ₂ , which corresponds in particular to the amplification factor of a yaw moment control (or the P component of the control) according to the prior art.

Time t ₂ is preferably chosen such that the amplification factor is reduced when the disruptive yaw rate caused by the tire burst becomes zero for the first time (in the case of a vehicle originally driving straight ahead, ie at the intersection of Ψ _act with the zero line). Due to the particularly continuous reduction of the amplification factor, the usual value K _normal thus results again at time t ₃ . The time interval between t ₃ and t ₂ should be a few seconds, in particular about 2 seconds, so that the driver can adapt to the situation by means of a steering angle δ _driver that is set permanently and can only be varied slightly.

According to a preferred embodiment of the invention, the ESC controller includes not only the P component but also a D component (differential component), which advantageously intervenes significantly earlier than the pure P controller. While the P controller only builds up its braking intervention as the control deviation increases, the D controller reacts as soon as a control deviation occurs, if an undesirable gradient of the yaw rate, i.e. a yaw acceleration, builds up. In the example of 3 a D controller would have almost reached its maximum manipulated variable at time t ₁ . Instead of or in addition to the modification of the P controller, the amplification factor K _D for the D component of the yaw moment control is therefore also dynamically increased. The time course of K _D is preferably chosen corresponding to the course of K discussed above, it also being possible for a more rapid reduction of K _D to be provided.

While the exemplary embodiment shown above shows the vehicle driving straight ahead, according to the method according to the invention, the measures described are also activated in any cornering situation. The threshold for determining the switching time is then selected on the basis of the yaw rate present at the time the tire burst was detected. A zero crossing of the measured yaw rate corrected by the value originally present is therefore detected.

An alternative preferred embodiment provides compensatory influencing of the steering effect of the burst tire in conjunction with the ESC/ABS measures or independently thereof via an applied, limited steering torque (short steering impulse or steering torque that decays over time). This is preferably done on the basis of the tire air pressure information, like the previous measures. The expediently gradual reduction of the compensatory steering torque has the advantage that a driver takeover/driver information is also effected.

A further preferred embodiment provides that the ESC and/or steering measures also take place when the driver accelerates in this driving situation, in particular for a limited period of time.

If a tire burst is detected, an ESC control system and/or, in the event of braking, an ABS control system intervenes early and strongly, the vehicle behaves uncritically throughout the control process and remains easily controllable even by an inexperienced driver, thus avoiding consequential damage.

Claims (12)

Method for increasing the driving stability of a vehicle, which is equipped with wheel speed sensors on all wheels and a braking system that allows at least a wheel-specific reduction in the braking force, characterized in that the braking system allows a driver-independent, wheel-specific buildup of braking force, and upon detection of a sudden loss of tire pressure Yaw moment compensation takes place through a driver-independent build-up of braking force, immediately after detection of a sudden loss of tire pressure for yaw moment compensation, a driver-independent build-up of braking force takes place on the wheel which is opposite the defective wheel on the same axle. procedure after claim 1 , characterized in that when a sudden loss of tire pressure is detected, the yawing moment is reduced during braking by the driver. procedure after claim 2 , characterized in that when the driver detects a sudden loss of tire pressure during braking, the yawing moment is reduced by limiting or reducing the braking force requested by the driver or applied with or without an auxiliary force on the defective wheel. Procedure according to one of Claims 1 until 3 , characterized in that the yaw moment compensation is carried out independently of braking by the driver. Procedure according to one of Claims 1 until 4 , characterized in that when tire pressure loss is detected, a first component of the braking force is built up as a control component, in particular the amount of the first component depending on the yaw acceleration present when the sudden tire pressure loss is detected and/or vehicle speed and/or an estimated coefficient of friction and/or a brake operation is selected by the driver. Procedure according to one of Claims 1 until 5 , characterized in that at least a proportion of the built-up braking force is determined as a control portion according to a deviation between a reference yaw rate and a measured yaw rate, in particular after a predetermined period of time only the control portion of the braking force is built up. Method according to at least one of the preceding claims, characterized in that when a sudden loss of tire pressure is detected, a predetermined braking force difference between the defective wheel and the opposite wheel on the same axle is set, which preferably has a predetermined fixed amount, which is in particular dependent on the at Detection of the sudden tire pressure loss present yaw acceleration and / or vehicle speed and / or an estimated coefficient of friction is selected. Method according to at least one of the preceding claims, characterized in that after a tire pressure loss has been detected, the gradient of a brake actuation by the driver is limited, in particular the pressure build-up in the wheel opposite the defective wheel on the same axle taking place in accordance with a brake slip control of the defective wheel . Method according to at least one of the preceding claims, characterized in that for at least partial yaw moment compensation, a steering moment is introduced into the steering train, which preferably has a predetermined fixed amount, which is in particular dependent on the yaw acceleration present when the tire burst is detected and/or vehicle speed and/or or an estimated coefficient of friction is selected. Method according to at least one of the preceding claims, characterized in that a tire pressure loss detection is activated when the vehicle drives faster than a minimum speed and / or the steering wheel speed falls below a predetermined steering threshold value and / or the engine torque is in a predetermined engine tolerance band and / or the wheel speed of all wheels is within a predetermined wheel speed tolerance band for a second predetermined period of time and that a sudden loss of tire pressure is detected when the wheel speed of a rear wheel drops suddenly or the wheel speed of a front wheel drops suddenly, without the corresponding rear wheel showing a corresponding behavior and/or a dem Wheel associated pressure sensor shows a sudden drop in pressure. Use of a method according to at least one of the preceding claims in a motor vehicle which is driven by an internal combustion engine and/or one or more electric motors. Electronic control device for a brake system, with an interface for at least two wheel speed sensors, comprising or connected to a hydraulic unit with at least one solenoid valve, characterized by a computing unit that uses a method according to one of Claims 1 until 10 executes

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