DE102005016131A1 - All-wheel-driven vehicle stabilization device, has control device executing driver-independent brake interferences to manipulate actual value, where interferences take place in respective wheel brake mechanisms of front axle or rear axle - Google Patents

Abstract

The device has a sensor device determining an actual value of a transverse dynamic vehicle size. A control device (12) compares the determined actual value with an evaluated reference value and executes driver-independent brake interferences for manipulation of the actual value. The interferences take place in wheel brake mechanisms of a front axle or in wheel brake mechanisms of a rear axle (14) of an all-wheel-driven vehicle (10). An independent claim is also included for a method for stabilization of an all-wheel-driven vehicle.

Description

The The invention relates to an apparatus and a method for Stabilization of a vehicle, with a sensor device for Determining an actual value of a lateral dynamic vehicle size, and with a control device which is assigned to one of the lateral dynamic vehicle size Calculated setpoint, wherein the control device determines the determined The actual value is compared with the calculated setpoint of the lateral dynamic vehicle size and on the basis of the comparison result driver-independent braking interventions to influence the actual value of the lateral dynamic vehicle size.

Such a device for stabilizing a vehicle is inter alia from the document DE 100 65 010 A1 out. In addition to means for detecting characteristic actual variables which describe the instantaneous driving state of the vehicle, the known device also comprises means for calculating setpoint values which are at least partially associated with the detected actual variables, wherein the detected actual variables are compared with the calculated setpoint variables and based on the comparison result driver-independent Brake intervention to influence the actual sizes are performed.

task The present invention is a device or a method of the type mentioned in such a way that one of the Conditions of an allradgetrie benen vehicle adapted implementation of driver-independent Brake intervention takes place.

These Task becomes according to the characteristics of claim 1 or of claim 8.

The Device for stabilizing a vehicle includes in addition to a Sensor device for determining an actual value of a lateral dynamic Vehicle size continues a control device associated with one of the lateral dynamic vehicle size Calculated setpoint, wherein the control device determines the determined The actual value is compared with the calculated setpoint of the lateral dynamic vehicle size and on the basis of the comparison result driver-independent braking interventions to influence the actual value of the lateral dynamic vehicle size. According to the invention it is a four-wheel drive vehicle, with the driver-independent braking interventions each axle in the wheel brake of a front axle or in the wheel brake of a rear axle of the four-wheel drive Vehicle done, so by both sides "symmetrical" operation of Wheel brake devices of the relevant axle.

There in the case of a four-wheel drive vehicle, both the wheels of the Front axle as well as those of the rear axle of a common Vehicle engine driven are usually not only a total of two axle differentials available, but also a common Longitudinal differential, which connects the two axle differentials and that the Purpose has, provided by a vehicle engine drive torque in a suitable way to distribute the two axes.

by virtue of of the specific control behavior of the longitudinal differential leads a Reduction of wheel torque on one axle to a corresponding one increase the wheel torque on the other axis, so by appropriate By way of actuation the wheel brake a defined wheel torque difference between the front axle and the rear axle of the four-wheel drive Vehicle, which makes it possible to influence the lateral dynamics of the vehicle and transverse dynamic instabilities, such as For example, in connection with cornering, evasive maneuvers, crosswinds and the like occur to compensate.

The otherwise usual for this purpose Use of structurally complex and consequently cost-intensive limited slip differentials Needless thus.

The execution the driver independent Brake intervention itself takes place in such a way that the determined actual value is returned to the calculated setpoint. The setpoint corresponds to one - in relation to the current one Driving situation - lateral dynamic stable driving behavior of the vehicle.

The driver-independent braking interventions can be a driver-side brake actuation and possibly those of other driver assistance systems, such as an anti-lock braking system (ABS), a traction control system (ASR) and the like, be superimposed.

advantageous versions the device according to the invention go from the subclaims out.

Around to be able to reliably detect the occurrence of lateral dynamics instabilities is It is also advantageous if the lateral dynamic vehicle size is a Yaw rate size that describes the yaw rate of the vehicle about its vertical axis, and / or around a float angle size, the a float angle of the vehicle between the longitudinal axis and the current one Direction of the vehicle describes, acts.

Especially can the four-wheel drive vehicle by axle actuation of Wheel brake the rear axle understeer driving behavior imprinted be, since in this case between the two axes evoked Wheel torque difference leads to that the vehicle is delayed more in the area of the rear axle than in the area of the rear axle Front axle. In an analogous way the four-wheel drive vehicle by axle actuation of the Wheel brake the front axle an understeering driving behavior impress.

It is accordingly possibly occurring for compensation lateral dynamic instabilities advantageous if the driver-independent braking interventions in the Wheel brake devices of the rear axle of the four-wheel drive vehicle then occur when the controller determines that the Vehicle oversteer Driving behavior has, and conversely, the driver-independent braking interventions in the wheel brake of the front axle of the four-wheel drive Vehicle then take place when the controller determines that the vehicle has an understeering driving behavior.

The Existence of an overriding or understeering driving behavior can be reliably through this Evaluation of one between the wheels the front axle and the wheels recognize the rear axle of the vehicle occurring skew angle difference. The skew angle difference can on the basis of a determined actual value of the yaw rate, a determined longitudinal velocity size, the the current longitudinal speed describes the vehicle, as well as a determined steering angle, the describes a steering angle set at a steering device, can be easily calculated.

The driver-independent Brake operations are preferably such that in the wheel brake each axis shall be the same or substantially the same the same wheel brake pressure is built up. The necessary control or Regulatory effort is comparatively low, so a cost-effective Realization of the device according to the invention possible is.

in this connection it is possible, the control device modulates the wheel brake pressure over time, for example in the form of a single or several temporally successive ones Dirac pulses, resulting in a particularly rapid and effective compensation possibly occurring transverse dynamic instabilities achieved can be.

In addition to the driver independent Brake operations, it is conceivable, the drive torque of the vehicle engine by appropriate intervention in a vehicle engine associated Reduce engine control. The concomitant decrease in the total kinetic energy of the vehicle affects in additional Way stabilizing on its driving behavior.

The inventive device or the inventive method will be explained in more detail below with reference to the accompanying drawings. there demonstrate:

1 An embodiment of the device according to the invention for a four-wheel drive vehicle,

2 an embodiment of the method according to the invention in the form of a flow chart.

1 shows an embodiment of the device according to the invention for a four-wheel drive vehicle.

The device for stabilizing the four-wheel drive vehicle 10 includes in addition to a sensor device 11 for determining an actual value ψ. _is β a transverse dynamic vehicle size _is furthermore a control device 12 , the one assigned to the lateral dynamic vehicle size setpoint ψ. _should , β _is calculated, the control device 12 the determined actual value ψ. _is , β _is at the calculated setpoint ψ. _should β _should the lateral dynamic vehicle size compares and on the basis of the comparison result driver-independent braking interventions to influence the actual value ψ. _is β _, the lateral dynamic vehicle size performs, the driver-independent braking interventions each axle in the two Radbremseinrichtungen 13a and 13b a front axle 13 or in the two wheel brake devices 14a and 14b a rear axle 14 of the four-wheel drive vehicle 10 respectively.

By way of example, the lateral dynamic vehicle size is a yaw rate, which is the yaw rate of the vehicle 10 describes about its vertical axis, and / or a Schwimmwinkelgröße, the float angle of the vehicle 10 between the longitudinal axis and the current direction of travel of the vehicle 10 describes. The following is intended to stabilize the four-wheel drive vehicle 10 Both the yaw rate and the slip angle size are taken into account, and it is in principle also possible to carry out these on the basis of only a single one of the two variables mentioned above.

The four-wheel drive vehicle 10 has a total of two axle differentials 20 and 21 on their part by a common longitudinal differential 22 which has the purpose of that of a vehicle engine 23 provided drive torque in a suitable manner on the two axes 13 and 14 to distribute.

wobei M_mot das vom Fahrzeugmotor 23 bereitgestellte Antriebsmoment, M_VA die Summe der einzelnen Raddrehmomente M_v,a, M_v,b an der Vorderachse 13 und M_HA die Summe der einzelnen Raddrehmomente M_h,a, M_h,b an der Hinterachse 14 des allradgetriebenen Fahrzeugs 10 bezeichnet.Due to the specific control behavior of the longitudinal differential 22 a reduction of the wheel torque on one axis leads to a corresponding increase of the wheel torque on the other axle, so that by appropriate axle-wise operation of the wheel brake 13a and 13b or the wheel brake devices 14a and 14d a defined wheel torque difference between the front axle 13 and the rear axle 14 of the four-wheel drive vehicle 10 can be caused. This follows a context of the figure

M _{mot of} the vehicle engine 23 provided drive torque, M _VA, the sum of the individual wheel torque M _{v, a} , M _{v, b} at the front axle 13 and M _{HA is} the sum of the individual wheel torques M _{h, a} , M _{h, b} at the rear axle 14 of the four-wheel drive vehicle 10 designated.

In particular, the four-wheel drive vehicle 10 by axle-wise actuation of the wheel brake 14a and 14b the rear axle 14 an understeering driving behavior to be impressed, since in this case between the two axes 13 and 14 caused wheel torque difference causes the vehicle 10 in the area of the rear axle 14 delayed more than in the area of the front axle 13 , In an analogous way can be the four-wheel drive vehicle 10 by axle-wise actuation of the wheel brake 13a and 13b the front axle 13 imprint an understeering driving behavior.

To compensate for any transverse dynamic instabilities occurring occur the driver-independent braking interventions in the Radbremseinrichtungen 14a and 14b the rear axle 14 of the four-wheel drive vehicle 10 accordingly, if the control device 12 determines that the vehicle 10 has an oversteering driving behavior. Conversely, the driver-independent braking interventions take place in the wheel brake 13a and 13b the front axle 13 of the four-wheel drive vehicle 10 then, if the control device 12 determines that the vehicle 10 has an understeering driving behavior. Indicates the vehicle 10 a neutral Fahrverhal th on, so omit the driver-independent braking interventions.

die sich unter Annahme eines linearen Fahrzeugmodells gemäß einem Zusammenhang der Gestalt

ergibt, wobei α_v den Schräglaufwinkel an der Vorderachse 13 des Fahrzeugs 10, α_h den Schräglaufwinkel an der Hinterachse 14 des Fahrzeugs 10, l den Längsabstand zwischen der Vorderachse 13 und der Hinterachse 14 des Fahrzeugs 10, ψ ._ist den Istwert der Gierratengröße, v_l eine Längsgeschwindigkeitsgröße, die die momentane Längsgeschwindigkeit des Fahrzeugs 10 beschreibt, und δ eine Lenkwinkelgröße, die einen an einer Lenkeinrichtung des Fahrzeugs 10 eingestellten Lenkwinkel beschreibt, bezeichnet (vgl. „Adam Zomotor, Fahrwerktechnik", 1. Auflage, Vogel-Verlag, S. 99 ff.).The presence of an oversteer or understeer driving behavior is determined by the controller 12 by evaluating one between the wheels of the front axle 13 and the wheels of the rear axle 14 of the vehicle 10 occurring skew angle difference detected,

assuming a linear vehicle model according to a context of the shape

results, where α _v slip angle at the front axle 13 of the vehicle 10 , α _{h is} the slip angle at the rear axle 14 of the vehicle 10 , l the longitudinal distance between the front axle 13 and the rear axle 14 of the vehicle 10 , ψ. _is the actual value of the yaw rate quantity, v _{l is} a longitudinal speed variable which is the instantaneous longitudinal speed of the vehicle 10 describes, and δ a steering angle, the one at a steering device of the vehicle 10 describes set steering angle, designated (see "Adam Zomotor, chassis technology", 1st edition, Vogel-Verlag, p 99 ff.).

The size l is a vehicle-specific constant that is in one of the control device 12 associated data store is stored.

In order to determine the longitudinal speed variable v ₁ and the steering angle variable δ, the device according to the invention has wheel speed sensors 11a and one of the steering device associated steering angle sensor 11b on, with the control device 12 the longitudinal speed variable v _l by evaluation of the wheel speed sensors 11a provided wheel speed signals and the steering angle δ by evaluation of the steering angle sensor 11b provided steering angle signal determined. The steering device is, for example, a steering wheel, by means of which the wheel steering angle of the steerable wheels of the front axle 13 of the vehicle 10 on the driver's side. The determination of the actual value ψ. _is the yaw rate variable is made using a yaw rate sensor 11c whose measuring axis is in the vertical direction of the vehicle 10 is oriented.

erfolgt. Zur Ermittlung der Querbeschleunigungsgröße a_q ist ein Querbeschleunigungssensor 11d vorhanden, dessen Messachse in Querrichtung des Fahrzeugs 10 orientiert ist. Der Querbeschleunigungssensor 11d ist – ebenso wie die Raddrehzahlsensoren 11a, der Lenkwinkelsensor 11b und der Gierratensensor 11c – gemeinsamer Bestandteil der Sensoreinrichtung 11.Furthermore, the control device determines 12 the actual value β _is the float angle variable on the basis of the determined actual value ψ. _is the yaw rate quantity, the determined longitudinal speed variable v _l and a determined lateral acceleration quantity a _q , the one on the vehicle 10 acting lateral acceleration describes what through temporal integration of a context of the shape

he follows. To determine the lateral acceleration quantity a _q is a lateral acceleration sensor 11d present, whose measuring axis in the transverse direction of the vehicle 10 is oriented. The lateral acceleration sensor 11d is - as well as the wheel speed sensors 11a , the steering angle sensor 11b and the yaw rate sensor 11c - Common part of the sensor device 11 ,

wobei m_g die Gesamtmasse des Fahrzeugs 10, C_v die Schräglaufsteifigkeit an der Vorderachse 13 des Fahrzeugs 10, C_h die Schräglaufsteifigkeit an der Hinterachse 14 des Fahrzeugs 10, l_v den Längsabstand zwischen der Vorderachse 13 und dem Fahrzeugschwerpunkt SP, l_h den Längsabstand zwischen der Hinterachse 14 und dem Fahrzeugschwerpunkt SP, l den Längsabstand zwischen der Vorderachse 13 und der Hinterachse 14 des Fahrzeugs 10, v_l die Längsgeschwindigkeitsgröße, δ die Lenkwinkelgröße und J_gz das Gierträgheitsmoment des Fahrzeugs 10 um dessen Hochachse bezeichnet (vgl. Adam Zomotor, Fahrwerktechnik", 1. Auflage, Vogel-Verlag, S. 99 ff.).The implementation of the driver-independent braking interventions per se is such that the determined actual value ψ. _is , β _is on the calculated setpoint ψ. _should , β _is the transverse dynamic vehicle size is returned, ψ. is → ψ. should , β is → β should , (1.5) where the setpoint ψ. _should , β _should - in relation to the current driving situation - transversely stable driving behavior of the vehicle 10 equivalent. Assuming a linear vehicle model results in the setpoint ψ. _should , β _{is supposed to} be the solution of differential equations of the shape

where m _{g is} the total mass of the vehicle 10 , C _v the skew stiffness at the front axle 13 of the vehicle 10 , C _h the skew stiffness at the rear axle 14 of the vehicle 10 , l _v the longitudinal distance between the front axle 13 and the vehicle center of gravity SP, l _h the longitudinal distance between the rear axle 14 and the vehicle center of gravity SP, l the longitudinal distance between the front axle 13 and the rear axle 14 of the vehicle 10 , v _{l is} the longitudinal speed magnitude, δ is the steering angle magnitude, and J _{gz is} the yaw moment of inertia of the vehicle 10 designated by its vertical axis (see Adam Zomotor, Fahrwerktechnik ", 1st edition, Vogel-Verlag, pp. 99 ff.).

The driver-independent braking interventions take place here in such a way that in the wheel brake 13a and 13b respectively. 14a and 14b the axis concerned 13 or 14 an identical or substantially identical wheel brake pressure is built up, p v, a ≈ p v, b or p Ha ≈ p h, b , (1.7)

According to an alternative embodiment of the device according to the invention, the wheel brake pressure of the control device 12 modulated in time, for example in the form of a single or a plurality of temporally successive Dirac pulses.

In addition to carrying out the driver-independent braking interventions, the control device reduces 12 the drive torque of the vehicle engine 23 by driver-independent interventions in a vehicle engine 23 assigned motor control 24 ,

To the driver about the presence of a transversely unstable driving state of the vehicle 10 to inform, operates the control device 12 simultaneously with the implementation of the driver-independent braking interventions or the driver-independent interventions in the engine control 24 a warning device 25 for issuing an acoustic and / or visual driver warning.

2 shows an embodiment of the method according to the invention in the form of a flow chart.

The inventive method is in an initialization step 30 started, whereupon in a first main step 31 the actual value ψ. _is the yaw rate quantity, the actual value β _is the buoyancy angle variable, the longitudinal velocity variable v ₁ , the steering angle variable δ and the lateral acceleration quantity a _{q are} determined. The determination of the actual value β _is the slip angle size _is effected by temporal integration of the equation (1.4).

At the first main step 31 followed by a second skin step 32 in which on the basis of the differential equations ( 1.6 ) the setpoint ψ. _to the yaw rate variable and the reference value β _to the yaw angle is determined. Furthermore, the calculation of the skew angle difference α _v - α _h according to equation (1.3).

In a third main step 33 becomes the first main step 31 determined actual value ψ. _is β, the yaw rate variable or yaw angle _is in the second main step 32 calculated setpoint ψ. _should , β _{should be} compared. If, on the basis of the comparison result, a respectively associated threshold Δψ results. _ref , Δβ _{ref is} exceeded in terms of amount, which is a transverse dynamic critical deviation between the actual driving behavior and the desired behavior of the vehicle 10 is marked with a subsequent fourth main step 34 continued. Otherwise, the process unexpectedly returns to the first main step 31 back.

Results in the fourth main step 34 that in the second main step 32 calculated slip angle difference α _v - α _h is negative, is on an oversteering driving behavior of the vehicle 10 closed and in a fifth main step 35 The driver-independent braking interventions are thus in the Radbremseinrichtungen 14a and 14b the rear axle 14 made that in each of the same or substantially the same wheel brake pressure p _{h, a} ≈ p _{h, b is} constructed. Subsequently, the method returns to the first main step 31 back.

Results in the fourth main step 34 that in the second main step 32 calculated skew angle difference α _v - α _{h is} not negative, so is in a sixth main step 36 checks if this is positive. If this is the case, it is due to an understeering driving behavior of the vehicle 10 closed and in a subsequent seventh main step 37 The driver-independent braking interventions are thus in the Radbremseinrichtungen 13a and 13b the front axle 13 made that in each of the same or substantially the same wheel brake pressure p _{v, a} ≈ p _{v, b is} constructed. Subsequently, the method returns to the first main step 31 back.

In addition to performing the driver-independent braking interventions, the drive torque of the vehicle engine 23 by driver-independent interventions in the vehicle engine 23 assigned motor control 24 reduced. Furthermore, the issuing of the acoustic and / or visual driver warning is initiated.

The driver-independent braking interventions or the driver-independent interventions in the engine control 24 take place in each case until, in the course of the periodic passage of the process in the third main step 33 it is found that the threshold Δψ. _ref , Δβ _ref amount is no longer exceeded. If this is the case, the driver-independent braking interventions are terminated by reducing the wheel brake pressure p _{h, a} , p _{h, b} or p _{v, a} , p _{v, b} . The same applies to the driver-independent interventions in the engine control 24 as well as the output of the visual and / or acoustic driver warning. The actual value ψ. _is β _, the yaw rate or bucket size is successively in this way to the calculated setpoint ψ. _should , β _{should be} returned.

Will be in the sixth main step 36 found that in the second main step 32 calculated skew angle difference α _v - α _{h is} not positive, this must therefore be substantially zero, so is on a neutral handling of the vehicle 10 closed and the process returns unexpectedly without performing the driver-independent braking interventions or the driver-independent interventions in the engine control 24 to the first main step 31 back.

Claims (8)

Device for stabilizing a vehicle, having a sensor device ( 11 ) for determining an actual value (ψ _is , β _is ) of a transverse dynamic vehicle size, and having a control device ( 12 ) That one of the transverse dynamic vehicle size associated setpoint (ψ. _Shall β _should be calculated), wherein the control device ( 12 _{Should be)} the detected actual value (ψ _is., Β) ψ with the calculated target value (., _Should β) compares the transverse dynamic vehicle size and independently of the driver on the basis of the comparison result a braking force for influencing the actual value (ψ. _{Is, is} β) of the transverse dynamic vehicle size carried out, characterized in that it is a four-wheel drive vehicle ( 10 ), wherein the driver-independent braking interventions each axles in the Radbremseinrichtungen ( 13a . 13b ) of a front axle ( 13 ) or in the wheel brake devices ( 14a . 14b ) a rear axle ( 14 ) of the four-wheel drive vehicle ( 10 ) respectively. Apparatus according to claim 1, characterized in that it is the transverse dynamic vehicle size to a yaw rate that the yaw rate of the vehicle ( 10 ) describes about its vertical axis, and / or a Schwimmwinkelgröße, the float angle of the vehicle ( 10 ) between the longitudinal axis and the current direction of travel of the vehicle ( 10 ), acts. Apparatus according to claim 1, characterized in that the driver-independent braking interventions in the Radbremseinrichtungen ( 14a . 14b ) of the rear axle ( 14 ) of the four-wheel drive vehicle ( 10 ) when the control device ( 12 ) determines that the vehicle ( 10 ) has an oversteering driving behavior, and conversely, the driver-independent braking interventions in the Radbremseinrichtungen ( 13a . 13b ) of the front axle ( 13 ) of the four-wheel drive vehicle ( 10 ) when the control device ( 12 ) determines that the vehicle ( 10 ) has an understeering driving behavior. Apparatus according to claim 3, characterized in that the control device ( 12 ) the presence of oversteer or understeer driving behavior on the basis of one between the wheels of the front axle ( 13 ) and the wheels of the rear axle ( 14 ) occurring skew angle difference (α _v - α _h ) detects. Device according to claim 1, characterized in that the driver-independent braking interventions take place in such a way that in the wheel brake devices ( 13a . 13b ; 14a . 14b ) of the axis concerned ( 13 ; 14 ) One each of the same or substantially the same in the wheel brake pressure (p _{v, a,} p _{v, a, h p, a,} p _{h) b} to be built. Apparatus according to claim 5, characterized in that the control device ( 12 ) modulates the wheel brake pressure (pv _{, a} , pv _{, a} ; ph _{, a} , ph _{, b} ) over time. Device according to claim 1, characterized in that the control device ( 12 ) in addition to carrying out the driver-independent braking interventions, the drive torque of a vehicle engine ( 23 ) by driver-independent interventions in a vehicle engine ( 23 ) associated motor control ( 24 ) decreased. A method for stabilizing a vehicle in which an actual value (ψ. _{Is, is} β) is determined a transverse dynamic vehicle size, and in which an associated transversely dynamic vehicle value setpoint (ψ. _Shall β _soll) is calculated, wherein the actual value (ψ determined . _{is, is} β) with the calculated target value (ψ. _shall β _{is to be} compared) of the transverse dynamic vehicle size and on the basis of the comparison result, driver-independent braking interventions for influencing the actual value (ψ., _is β be performed) of the transverse dynamic vehicle size, characterized in that that it is a four-wheel drive vehicle ( 10 ), wherein the driver-independent braking interventions each axles in the Radbremseinrichtungen ( 13a . 13b ) of a front axle ( 13 ) or in the wheel brake devices ( 14a . 14b ) a rear axle ( 14 ) of the four-wheel drive vehicle ( 10 ) respectively.