DE102009022311A1 - Motor vehicle stability controlling/regulating method, involves activating contact for reduction of drive torque of vehicle and/or axle and/or wheel with upper limit to target drive torque at beginning of contact with detected instability - Google Patents

Abstract

The method involves detecting potential stability-critical driving conditions. An upper limit (9) of a torque starting point (11) is set when the conditions are detected, where the point is a control/regulation target drive torque (12) of a motor vehicle and/or an axle and/or a wheel at beginning of a control/regulation contact of a stability control/regulation system. The contact is activated for reduction of a drive torque (8) of the vehicle and/or the axle and/or the wheel with the upper limit to the target drive torque at the beginning of the contact with detected instability. An independent claim is also included for a control/regulation device for a motor vehicle.

Description

The The present invention relates to a method of vehicle stability control and a control apparatus for a motor vehicle for carrying out the Process.

Known are numerous devices and methods for traction / traction slip / brake control systems, alone or in conjunction with, or integrated into, parent Driving stability systems the braking and traction performance as well as the driving stability under Improve and optimize a wide range of road friction coefficients help.

These Systems are hardware based z. B. on electromechanical-hydraulic, electromechanical-pneumatic or purely electromechanical actuators in conjunction with an electronic Control unit and associated various sensors. Further the known systems have conventional interfaces and / or Bus connections to actuation and switching elements and other control systems and Display units in the vehicle system network.

The Control systems essentially control or regulate z. B. slip, frictional, lateral acceleration, longitudinal acceleration, längsneigungs-, bank angle, yaw angle and / or buoyancy dependent, etc., generally therefore driving condition-dependent, on the one hand the drive torque and on the other hand also by individual brake intervention the wheel brake moments. For vehicles with internal combustion engine is called Drive torque, the engine torque or the corresponding cardan torque or wheel torque over "slow" fill engagement and "fast" ignition angle / injection blanking intervention controlled.

at modern powerful vehicle engines, especially at Engines with turbocharging, it may be due to the associated special Engine characteristics with relatively moderately increasing driver specifications already come to very dynamic and high engine torque increases. This may happen the driving stability behavior of the vehicle, mainly on medium and low road / tire traction ratios (eg ice, snow, wet pavement, loose ground, etc.) clearly negatively affected, as the control systems due to existing dead or delay times and in addition existing communication times among themselves occurring instabilities no longer optimal and fast enough to regulate and reduce can.

The Consequences of this are mainly, next to a temporary unstable driving behavior by a poor traction and acceleration performance too high Antriebsradschlupf, and thus associated with the driver, subjectively reduced control comfort behavior.

Of the Invention is based on the object, a method and a control / regulating device to carry out of the method, which is simpler and more effective Integrability in a vehicle, the vehicle dynamics and ride comfort and increase vehicle safety.

The solution This object is achieved by the features of the independent claims. The under claims have advantageous developments of the invention the subject.

• – Erfassen einer potentiell stabilitätskritischen Fahrsituation,
• – Setzen einer Obergrenze eines Momentenaufsetzpunktes bei erfasster potentiell stabilitätskritischer Fahrsituation, wobei der Momentenaufsetzpunkt ein Steuer-/Regelvorgabeantriebsmoment des Fahrzeugs und/oder zumindest einer Achse und/oder zumindest eines Rades zu Beginn eines Steuer-/Regeleingriffs eines Stabilitätssteuer/regelsystems ist,
• – Erfassen einer Instabilität des Fahrzeugs und/oder zumindest eines Rades des Fahrzeugs, und
• – Aktivieren des Steuer-/Regeleingriffs zur Reduzierung eines Antriebsmomentes des Fahrzeugs und/oder zumindest einer Achse und/oder zumindest eines Rades mit dem begrenzten Momentenaufsetzpunkt als Steuer-/Regelvorgabeantriebsmoment zu Beginn des Steuer-/Regeleingriffs bei erfasster Instabilität.

Thus, the invention is solved by a method for vehicle stability control, comprising the following steps:

• Detecting a potentially stability-critical driving situation,
• Setting an upper limit of a torque application point upon detection of a potentially stability-critical driving situation, wherein the torque application point is a control target drive torque of the vehicle and / or at least one axle and / or at least one wheel at the beginning of a control operation of a stability control system,
• Detecting an instability of the vehicle and / or at least one wheel of the vehicle, and
• Activating the control action to reduce a drive torque of the vehicle and / or at least one axle and / or at least one wheel with the limited torque attachment point as the control default drive torque at the beginning of the control intervention with detected instability.

Thus, according to the invention, a potentially stability-critical driving situation is detected due to boundary conditions or characteristic environmental conditions. In the presence of such a potentially stability-critical driving situation, an upper limit of the torque application point is set preventively. This happens even before the vehicle actually becomes unstable and a control / regulation intervention is necessary. This preventive setting of the upper limit of the torque application point avoids limiting the drive torque of the vehicle or individual wheels or individual axles until the control intervention is activated due to an actual instability of the vehicle. This avoids unnecessary drive torque influences. Instead of actually reducing the drive torque, the start of control, ie the control / default drive torque at the beginning of a control / regulating intervention, manipulated. This leads to a significant driving stability increase hunger, especially in high-performance vehicles and vehicles with a turbo engine, where a highly dynamic drive torque build-up can take place. As a direct result, vehicle dynamics, vehicle performance, vehicle safety and ride comfort increase.

In Advantageous embodiment is provided that the detection of the potentially critical to stability Driving situation a recognition and / or validation and / or verification and / or classifying the potentially stability-critical driving situation, in particular based on sensed and / or calculated and / or predicted and / or predicted sizes. Under the recognition of a potentially stability-critical driving situation is the determination of whether such a driving situation exists or not. Depending on how acute or dangerous such a potential stability-critical Estimated driving situation you can classify the driving situation. Furthermore, the sensed, calculated, predicated and / or predicted sizes, constraints or characteristic environmental conditions are used to both recognizing and classifying a potential critical to stability Validate and / or verify the driving situation. The sensed, calculated, predicated or predicted sizes or boundary conditions or characteristic environmental conditions are hereafter specified in more detail.

In preferred embodiment It is envisaged that the potentially stability-critical driving situation, based is detected on at least one tire / road friction coefficient information. The tire / road friction information preferably includes the frictional connection and / or the exploited traction between wheels and / or Axles and the roadway. In a particularly preferred embodiment is an ambient air temperature and / or tire temperature and / or Roadway temperature and / or humidity and / or a road friction coefficient and / or tire friction value for detecting this tire / road friction coefficient information used. Thus, the tire / road friction coefficient information can be obtained directly or indirectly predicates via sensors be recorded. Alternatively or additionally, the tire / road friction coefficient information for example, from temperature and / or humidity values estimated become. Furthermore, it is advantageous based on a measured Outside temperature, on suspected Niederreibwertverhältnisse close, the robustness of potentially stability-critical driving situation detection to increase and, for example, detecting tire / road friction information to verify and validate.

Further It is advantageous that the potentially stability-critical driving situation, based on a driver's moment directly or indirectly determined by a driver is detected. Such driver driver torque may be, for example be removed on a drive or crankshaft or from the Motor control are read. Another way to capture the Driver's torque or driver's request torque is provided by the accelerator pedal.

In preferred embodiment becomes the potentially stability critical Driving situation, based on a current gear and / or Powertrain gain and / or axle-specific drive torque distribution and / or wheel-individual Drive torque distribution detected. Especially when using Driven both to the longitudinal as well as lateral distribution of the moment can the drive torque distribution both axle and wheel are recorded individually. By capturing the gear stage, powertrain gain and / or the drive torque distribution you can capture the potentially stability-critical driving situation restrict to that extent that you are advantageously on a particular selected gear or a specific gear ratio, in the danger of potential instability due to dynamically high torque increases is particularly high, limited.

Of Another advantage is that the potentially stability critical Driving situation, based on a driving speed, in particular sensed by means of a wheel speed sensor is detected. Thus one can determine the driving speed for recognizing, validating, Verify and / or classify a potentially stability-critical driving situation use.

Further advantageous quantities to be detected on which the detection of the potentially stability-critical driving situation can be based are: vehicle steering angle and / or vehicle lateral acceleration and / or vehicle yaw rate and / or vehicle longitudinal acceleration and / or longitudinal vehicle pitch and / or longitudinal vehicle pitch and / or vehicle bank angle and / or or road bank, as well as derived and determined sizes. By detecting the vehicle steering angle, in particular the potentially stability-critical driving situation can be detected to the extent that a straight-ahead or cornering of the vehicle is detected. The vehicle lateral acceleration can specify the currently used traction between the vehicle and the roadway in the transverse direction. The vehicle yaw rate indicates a vehicle rotation rate about the vertical axis, which in turn can be closed to a potentially stability-critical driving situation. By detecting lane longitudinal and bank, the detection of the potential stability-critical driving situation on certain roadway slopes, in which the risk of instability is particularly disturbing, are limited.

Further advantageous sizes, which used to drive the potentially stability-critical driving situation are: engine speed and / or wheel contact forces and / or Loading as well as dependency of freely selectable Regulation modes. Such selectable Rule modes, which include the detection of potentially stability-critical Can influence driving situation with are z. B. driver-selectable sport mode, Traction mode or snow chain mode.

In Another advantageous embodiment is provided that the upper limit of the torque application point is set lower than a predicted one Driving moment, the predicted Drive torque the control / default drive torque at the beginning of a control action, when activating the control / regulation intervention without prior detection of a potentially stability-critical driving situation, equivalent. This predicated Drive torque as it is used when no potential stability-critical Driving situation is detected, for example, by the engine control provided or removed at the crankshaft and is predicated on adjusted static and dynamic losses. In order to increase the vehicle stability, is the upper limit of the torque application point when detected potentially stability-critical driving situation set lower than this predicted drive torque. As a general rule is set with a low controller start torque set point for the control command input torque a better initial stability of the vehicle achieved as having a higher torque application point. In addition, in the subsequent rule course time delays shortened to the entry into the quasi-steady control state, from which also an increase the driving stability results. On the other hand, the torque application point should not be too low be set as this is an uncomfortable and unpleasant longitudinal jerk lead in the vehicle can.

In preferred embodiment are the upper limit of the torque application point and / or the course the upper limit of the torque application point continuously before New control / regulation intervention determined. The moment setting point becomes permanently calculated and taken into account in a control device static and dynamic drive losses. When detected instability of the vehicle, both a wheel instability As well as a total vehicle instability, this upper limit of the Torque setpoint as the beginning of the control default drive torque and transmitted via interface to the engine control.

The Determining the upper limit of the torque application point is different Way feasible. In the following, advantageous possibilities for this pointed out: So it is preferable, starting from a defined real or estimated or derived from the driver request drive torque increase above a certain threshold and / or gradient linear ramped Limit for to execute the torque application point. This linear ramped Limitation occurs before the start of the control intervention in the vehicle calculated until due to a detected instability the vehicle the control / regulation intervention is activated and the actual Drive torque of the vehicle is reduced. It can be the slope this linear ramped Limitation of the upper limit of the torque application point variable in dependence from Z. As the catch level, the powertrain gain, the driving speed and from the moment level and / or other current state conditions be calculated.

A further advantageous possibility fixing the upper limit of the torque application point is represent the linear boundary just described via non-linear limiting functions, to thereby advantageously estimate a follow-up behavior continuously.

A Another alternative to defining the upper limit of the torque application point it is, a fixed, in particular by means of PT1 filter with fixed filter constants, or variable filtering, depending on from the difference between unfiltered and currently filtered estimated Drive torque to make.

Of Furthermore, it is advantageous that the potentially stability critical Driving situation is assessed and / or classified, and an amount and / or course and / or gradient of the upper limit of the torque application point dependent on the evaluated and / or classified potentially stability critical Driving situation is determined. So can advantageously about the Values and / or classify the potentially stability critical Driving situation whose danger or potential influence of driving dynamics and Driving comfort to be determined. In order to be able to individually different potential possible stability-critical To react to driving situations, the upper limit of the torque application point or its course or gradient corresponding to this scored and / or classified potentially stability-critical driving situation established.

The invention further comprises a control device for a motor vehicle, comprising one for carrying out the inventions trained control method according to the invention. Of course, the already discussed advantageous embodiments of the method according to the invention also find corresponding applications in the context of the control / regulating device according to the invention.

in the Below, the invention is based on an embodiment in connection explained in more detail with the accompanying drawing. The only one shows

1 a diagram with torque curves before and after the control / regulating intervention.

Look at the only one 1 an embodiment of the invention will be explained in more detail. 1 shows a diagram 1 with a horizontal axis 2 and an orthogonal axis 3 , The horizontal axis 2 shows the time t in seconds [s]. The orthogonal axis 3 shows the moment in [Nm].

Furthermore, in the diagram 1 represented as a vehicle dynamics control system at the time 4 is activated. At this time 4 the activation of the control / regulation intervention takes place. This results in a controller status 5 ,

In the diagram 1 the following graphs can be seen: a driver torque 6 , an actual crankshaft torque 7 , derived from the engine control, a predicted drive torque 8th , calculated taking into account static and dynamic losses, a linear ramp of the upper limit 9 and a history of a control command drive torque 12 , Furthermore, the diagram shows 1 at the predicted drive torque 8th at the time 4 a first moment attachment point 10 how it is used without the existence of a potentially stability-critical driving situation, and at the intersection of the course of the upper limit 9 with the control command input torque 12 at the time 4 a second torque application point 11 , This second moment attachment point 11 represents the beginning of the control command drive torque 12 at detected stability-critical driving situation.

If a stability-critical driving situation is detected - ie at the time at which the start of control is generally also triggered - one would like to jump directly to the "situation-appropriate" torque attachment point. This is inventively the second Momentensetzpunkt 11 , In controls according to the prior art is the, not appropriate to the situation, higher lying first moment attachment point 10 used, by which the instability was not optimally adjusted but only in the course of the follow-up regulation could be corrected or had to. The first moment attachment point 10 can z. T. advantageously continue to be used, even stability-critical situations (eg., When driving straight ahead or in other cornering and driving situations). If, however, the control / regulation device recognizes a potentially stability-critical driving situation, the control / regulating engagement with the second torque application point will be detected when an unstable position of the vehicle is detected 11 , ie the course of the upper limit 9 at the time 4 , activated.

By using this upper limit or second moment setting point 11 which is lower than the first torque application point 10 , an improved initial stabilization of the vehicle is achieved upon activation of the control action. This results in both increased vehicle safety and dynamics as well as increased comfort behavior of the vehicle. An actual, for the driver noticeable limitation of the drive torque is delayed until the vehicle is actually unstable and the activation of the control / regulating intervention is necessary to limit the actual drive torque.

Next The above written disclosure is expressly incorporated herein by reference the disclosure referenced in the figures.

Claims (12)

A vehicle stability control method, comprising the following steps: - detecting a potentially stability-critical driving situation, - setting an upper limit ( 11 ) of a torque application point with detected potentially stability-critical driving situation, wherein the torque application point a control input torque ( 12 ) of the vehicle and / or at least one axle and / or at least one wheel at the beginning ( 4 ) is a control intervention of a stability control system, detecting instability of the vehicle and / or at least one wheel of the vehicle, and activating the control action for reducing a drive torque of the vehicle and / or at least one axle and / or at least one wheel with the upper limit ( 11 ) of the torque application point as the control default drive torque ( 12 ) at the start ( 4 ) of the control action at detected instability. Method according to claim 1, characterized in that that capturing the potentially stability-critical driving situation a recognition and / or validation and / or verification and / or Classifying the potentially stability-critical driving situation, in particular based on sensed and / or calculated and / or predicted and / or predicted sizes. Method according to one of the preceding claims, characterized in that the potentially stability-critical driving situation based on at least one tire / Fahrbahnreibwertinformation ( 6 ) is detected. Method according to claim 3, characterized that an ambient air temperature and / or tire temperature and / or Roadway temperature and / or humidity and / or a road friction coefficient and / or tire friction value for detecting the tire / road friction coefficient information be used. Method according to one of the preceding claims, characterized characterized in that the potentially stability-critical driving situation based on a driver's moment directly or indirectly determined by a driver is detected. Method according to one of the preceding claims, characterized characterized in that the potentially stability-critical driving situation based on a current gear and / or powertrain gain and / or Axis-specific drive torque distribution and / or wheel-individual Drive torque distribution is detected. Method according to one of the preceding claims, characterized characterized in that the potentially stability-critical driving situation based at a driving speed, in particular sensed by means of a Radgeschwindigkeitssensorik, is detected. Method according to one of the preceding claims, characterized characterized in that the potentially stability-critical driving situation based a vehicle steering angle and / or vehicle swimming angle and / or a vehicle lateral acceleration and / or Fahrzeuggiergeschwindigkeit and / or Vehicle longitudinal acceleration and / or vehicle pitch and / or lane inclination and / or vehicle bank and / or road bank becomes. Method according to one of the preceding claims, characterized in that the upper limit ( 11 ) of the torque application point is set lower than a predicted drive torque ( 8th ), where the predicted drive torque ( 8th ) the control / default drive torque at the beginning ( 4 ) of a control / regulatory intervention, upon activation of the control / regulation intervention without prior detection of a potentially stability-critical driving situation, corresponds. Method according to one of the preceding claims, characterized in that the upper limit ( 11 ) of the torque application point and / or the course ( 9 ) of the upper limit of the torque application point is continuously redetermined before the control / regulating intervention. Method according to one of the preceding claims, characterized in that the potentially stability-critical driving situation is evaluated and / or classified, and an amount and / or course ( 9 ) and / or gradient of the upper limit ( 11 ) of the torque application point is determined as a function of the evaluated and / or classified potentially stability-critical driving situation. Control / regulating device for a motor vehicle, comprising one to carry a method according to a of the preceding claims trained control unit.