Method for operating an adjustable roll stabilizer

Abstract

A method for operating an adjustable roll stabilizer (1) of a motor vehicle, the adjustable roll stabilizer (1) having an actuator (2) which is rotatable relative to a rotation axis (3) in order to twist two stabilizer sections (6a, 6b) connected with the actuator relative to one another about the rotation axis (3), wherein the stabilizer sections (6a, 6b) are respectively coupled with a wheel suspension (7a, 7b, 8a, 8b, 9a, 9b) radially away from the rotation axis (3), wherein the actuator (2) is actuated on the basis of a system theoretical torque preset on the vehicle side, and wherein the preset system theoretical torque is checked for an admissibility in terms of a vehicle admissible roll torque distribution (β).

Description

TECHNICAL FIELD

[0001] The present application relates to a method for operating an adjustable roll stabilizer of a motor vehicle, and to a twin-axle motor vehicle. BACKGROUND

[0002] It is known from motor vehicle technology, in particular from chassis technology, to influence the roll or roll behavior of a motor vehicle by means of a so-called roll stabilizer. In the basic configuration, the roll stabilizer is a generally C-shaped torsion bar spring which is rotatably supported in a central region relative to the vehicle structure and whose opposite outer ends are respectively coupled to a wheel suspension by means of a coupling element, a so-called swing strut. By this configuration, the roll stabilizer ensures that the vehicle body, when cornering, not only presses down on the side of the curve outside (due to centrifugal forces), but also ensures that the wheels on the inside of the curve are slightly lowered. The roll stabilizer increases the driving directional stability of the vehicle and reduces the lateral inclination of the vehicle structure (roll), thereby making cornering safer and more comfortable.

[0003] In order to further improve the vehicle stability and driving comfort, it is known to implement such a roll stabilizer to be adjustable. In this case, the roll stabilizer comprises an actuator and is divided into two stabilizer sections which are torsionally adjustable relative to one another about a rotation axis by means of the actuator. Due to the torsion of the stabilizer sections relative to one another, the roll movement of the vehicle structure is produced in a targeted manner or the roll movement of the vehicle structure due to external influences is counteracted in a targeted manner. Adjustable roll stabilizers are known from the prior art whose actuators have an electric motor which is in driving connection with a mechanical transmission, in particular in the configuration form of a multi-stage planetary transmission, in order to obtain a suitable rotational speed or torque. In this regard, reference is made, by way of example, to DE 10 2016 219 399 A1.

[0004] In addition to the structural design of the adjustable roll stabilizer, its appropriate handling is also a technical challenge. In this regard, reference is made, for example, to DE 10 2009 007 357 A1, which describes a method for operating an adjustable roll stabilizer of a twin-axle motor vehicle. In particular, the priority of different control strategies is addressed as a topic in the case of a twin-axle vehicle roll support.

[0005] It is generally possible to achieve that an adjustable roll stabilizer is used to distribute a total support torque for a motor vehicle between a front axle and a rear axle in the range of active roll stabilization of the motor vehicle equipped with the adjustable roll stabilizer in order to improve the driving stability and / or the driving comfort in this way, for example, in certain situations. In particular in a motor vehicle with two axles having an adjustable roll stabilizer on the front axle and in addition an adjustable roll stabilizer on the rear axle, the total support torque for the motor vehicle is distributed proportionally between the actuator assigned to the front axle and the actuator assigned to the rear axle, wherein the distribution can be influenced by a corresponding manipulation. In a manner known per se, the motor vehicle is, for example, in principle more prone to understeering when the total support torque is carried by the actuator of the front axle to too great an extent. Conversely, the motor vehicle is in principle more prone to oversteering when the total support torque is carried by the actuator of the rear axle to too great an extent. SUMMARY

[0006] It is an object of the application to specify a method for operating an adjustable roll stabilizer of a motor vehicle, which method contributes to preventing oversteering and / or understeering to too great an extent. Furthermore, a motor vehicle with two adjustable roll stabilizers is to be specified, in which oversteering and / or understeering to too great an extent is correspondingly prevented.

[0007] The object mentioned is achieved firstly by a method for operating an adjustable roll stabilizer of a motor vehicle. In the method according to the application, the adjustable roll stabilizer has an actuator, which is rotatable about a rotation axis in order to twist two stabilizer segments connected to the actuator relative to one another about the rotation axis. The stabilizer segments are respectively coupled to a wheel suspension radially away from the rotation axis. According to the application, the actuator is manipulated on the basis of a system theoretical torque preset in advance at the vehicle side, wherein the preset system theoretical torque is checked for an admissibility in terms of the admissible roll torque distribution of the vehicle.

[0008] Accordingly, it is first of all apparent from the application that the adjustable roll stabilizer can be used not only to influence the roll behavior of the vehicle structure of the motor vehicle, but that, in addition, the roll torque distribution of the motor vehicle (i.e. the distribution of the overall roll torque supported by the vehicle onto the two axles) can also be influenced by means of the adjustable roll stabilizer. Here, the overall roll torque supported by the vehicle is divided into a roll torque supported by the front axle and a roll torque supported by the rear axle, wherein, by using at least one adjustable roll stabilizer (on at least one axle of the motor vehicle), it is already possible to influence the distribution of the supported roll torque between the axles within certain limits. In order to avoid an oversteering or understeering behavior of the motor vehicle, it has been formed according to the application that the admissibility of a (vehicle-side) pre-set system theoretical torque (on the basis of which the actuator of the adjustable roll stabilizer is actuated) is checked with regard to the admissibility of the roll torque distribution of the vehicle.

[0009] According to an advantageous design of the method, the checking of the admissibility of the system theoretical torque is carried out in such a way that the resulting roll torque distribution is calculated for the pre-set system theoretical torque and a comparison is carried out as to whether the roll torque distribution is within an admissible range.

[0010] It is advantageous here that the admissible range of the roll torque distribution is pre-set by means of at least one limit curve which is dependent, inter alia, on the vehicle speed. Conveniently, the limit curve is here a limit curve which is calculated, for example, by means of previous driving tests of the motor vehicle and / or by means of a modeling of the motor vehicle.

[0011] According to a particularly preferred refinement, the admissible range of the roll torque distribution is limited by an upper limit curve and a lower limit curve, wherein an admissible roll torque distribution exists when the calculated roll torque distribution is below the upper limit curve for the roll torque distribution and above the lower limit curve for the roll torque distribution. In other words, a range of admissibility is obtained between the upper limit curve and the lower limit curve, within which range the roll torque distribution is allowed to move without the motor vehicle being exposed to the danger of oversteering or understeering in a particular manner.

[0012] An advantageous refinement of the method proposes that, in the absence of admissibility, i.e. when the system theoretical torque pre-set for the adjustable roll stabilizer leads to a roll torque distribution outside the admissible range, more drastic measures are initiated. Conveniently, it can be proposed that the more drastic measures are initiated only after a maximum admissible fault tolerance time has been exceeded.

[0013] The further measures can in principle be various measures, for example optical and / or acoustic warning signals, in particular. Since the non-permitted roll torque distribution impairs the driving safety of the motor vehicle, it can be expedient to propose that the further measures at least involve a changeover to a safe state, in particular a switching off of the adjustable roll stabilizer of the motor vehicle. If the motor vehicle is equipped with a plurality of adjustable roll stabilizers, it can be proposed to expediently switch off two adjustable roll stabilizers.

[0014] In order to check the permissibility of the system theoretical torque preset, in particular in order to calculate the roll torque distribution required for this, an advantageous design of the method described within the scope of the application proposes that, in addition to the system theoretical torque preset for the adjustable roll stabilizer, the system theoretical torque preset for a further adjustable roll stabilizer of the motor vehicle is also taken into account. In other words, the permissibility check for the roll torque distribution accesses the system theoretical torque on the front axle and the system theoretical torque on the rear axle, respectively.

[0015] Within the scope of the application, "roll torque distribution" is understood in the strict sense as the ratio of the roll torque supported by the first axle (front axle) to the roll torque supported overall by the motor vehicle. Correspondingly, the roll torque distribution is expediently calculated from the ratio of the roll torque supported by the first axle (front axle) to the roll torque supported overall by the motor vehicle. In this regard, it should be mentioned that the roll torque supported overall on the motor vehicle is calculated from the sum of the roll torque supported by the first axle (front axle) and the roll torque supported by the second axle (rear axle).

[0016] The actuator of the adjustable roll stabilizer can be controlled in different ways. Here, in particular different control systems can be used. According to an expedient refinement of the method, the actuator is controlled on the basis of the system theoretical torque in such a way that the system theoretical torque is taken into account to determine a theoretical angle, and then a motor theoretical torque for controlling the motor of the actuator is calculated from this theoretical angle by means of a yaw-speed controller.

[0017] The method described previously for operating an adjustable roll stabilizer of a motor vehicle is itself intended to operate the adjustable roll stabilizer first. The admissibility check described in the context of the application is therefore carried out in the context of controlling the respective adjustable roll stabilizer. Since a motor vehicle can be equipped with an adjustable roll stabilizer on each of its axles, it is proposed according to an advantageous development of the method that the method is used to operate two adjustable roll stabilizers of the motor vehicle in such a way that the actuator of any one of the two adjustable roll stabilizers is operated on the basis of a system theoretical torque which is predefined for the respective axle on the vehicle side, wherein the admissibility of the predefined system theoretical torque in terms of the admissible roll torque distribution of the vehicle is checked independently accordingly. The check of the admissibility of the system theoretical torque is thus carried out independently on the level of each axle of the motor vehicle. It can advantageously be proposed that in the event of a non-admissibility of the system theoretical torque, this non-admissibility is communicated to the control system of the respective other axle, so that appropriate countermeasures can be taken across axles accordingly.

[0018] Furthermore, the object stated in the introduction is also achieved by a two-axle motor vehicle having two adjustable roll stabilizers. This relates to a two-axle motor vehicle having two adjustable roll stabilizers which are suitable in particular for carrying out the method described above and one of which is assigned to the front axle and the other of which is assigned to the rear axle, wherein each of the two adjustable roll stabilizers can be operated in dependence on a reference variable in the form of a system theoretical torque which is predefined on the vehicle side and which is related to the axle, wherein each of the adjustable roll stabilizers is assigned a device for checking the admissibility of the system theoretical torque related to the axle in terms of the admissible roll torque distribution of the vehicle. BRIEF DESCRIPTION OF DRAWINGS

[0019] The application is explained further below with the aid of the drawings. Further advantageous embodiments of the application also result therefrom. In the drawings:

[0020] Figure 1 An adjustable roll stabilizer for a motor vehicle is shown in a schematic view,

[0021] Figure 2 A diagrammatic illustration of a control strategy of an adjustable roll stabilizer is shown,

[0022] Figure 3An exemplary diagram showing two limit curves for roll moment distribution,

[0023] Figure 4 A diagrammatic overview for roll stabilization on a double axle motor vehicle is shown taking into account the roll moment distribution. DETAILED DESCRIPTION

[0024] To show the field of application of the invention, Figure 1 An adjustable roll stabilizer 1 is first shown in a schematic view. The adjustable roll stabilizer 1 is part of a not completely shown running gear of a (not shown) motor vehicle. The reference merely indicates a vehicle structure 10 of the motor vehicle. The roll stabilizer 1 is also part of an axle of the motor vehicle, for example the front axle and / or the rear axle of the motor vehicle can be equipped with the adjustable roll stabilizer 1.

[0025] As Figure 1 The left wheel 7a and the right wheel 7b arranged on the opposite vehicle side are each connected to the vehicle structure 10 by means of a not further explained steering mechanism 8a or 8b, as shown. The wheel 7a and the steering mechanism 8a or the wheel 7b and the steering mechanism 8b each form a unit and are each coupled by means of a swing link 9a or 9b to one end of the associated stabilizer section 6a or 6b of the adjustable roll stabilizer 1. The left stabilizer section 6a and the right stabilizer section 6b are connected to each other in the vehicle middle by means of an actuator 2 shown as a substantially cylindrical body.

[0026] In a manner known per se, the adjustable roll stabilizer 1 is rotatably supported with respect to the vehicle structure 10 about a rotation axis 3 for which a left stabilizer bearing 11a and a right stabilizer bearing 11b are used, which surround the associated stabilizer section 6a or 6b according to Figure 1 The left stabilizer bearing 11a and the right stabilizer bearing 11b are each shown (simplified) in the form of a U around the region of the associated stabilizer section 6a or 6b facing the actuator 2.

[0027] The actuator 2, shown here as a cylinder, generally comprises a housing (not shown in detail) that is substantially rotationally symmetrical with respect to the axis of rotation 3. Within this housing are arranged an electric motor 4, a multi-stage planetary gearbox 9, and a speed sensor 13 (each indicated only by reference numerals). Stabilizer sections 6a and 6b are drivenly connected to each other via the electric motor 4 and the multi-stage planetary gearbox 5. When the actuator 2 is stationary, the two stabilizer sections 6a and 6b are rigidly connected to each other via the stationary electric motor 4 and the multi-stage planetary gearbox 5 driven by it. However, by operating the electric motor 4, the stabilizer sections 6a and 6b can twist relative to each other about the axis of rotation 3, depending on the direction of rotation of the electric motor 4. Here, the multi-stage planetary gearbox 5 has a fixed transmission ratio preset between the drive unit (electric motor 4) and the driven unit (the right stabilizer section 6b connected to the output end of the gearbox). Therefore, the adjustable roll stabilizer 1 can be adjusted in a manner known per se.

[0028] Depending on the operating conditions of the adjustable roll stabilizer 1 or the vehicle equipped with an adjustable roll stabilizer, the stabilizer sections 6a and 6b interconnected by the actuators 2 may twist, depending on the torque M generated by this twist acting around the rotation axis 3. 系统 This torque M 系统 The system torque is applied to actuator 2.

[0029] With the help of the roll stabilizer 1, the roll moment M acting between the vehicle structure 10 and the wheels 7a and 7b can be controlled. 侧倾 Provide support. The supportable roll moment M can be affected by adjusting the roll stabilizer 1. 侧倾 To control the roll stabilizer 1 as needed, the left wheel 7a or the right wheel 7b is each equipped with a height sensor 12a or 12b. These height sensors enable the detection of wheel lifting and lowering movements of their respective wheels, with the height z of the left wheel as the reference. 7a In the form of or in the height z of the right wheel 7b The detection results are output in the form of a speed sensor 13. Furthermore, the rotation of the electric motor 4 can be detected by the speed sensor 13 and output as a speed signal, representing the motor speed n.

[0030] The following is based on Figure 2 The control strategy shown in the document elaborates on the control strategies employed in... Figure 1 The control of the adjustable roll stabilizer 1 is schematically shown. Accordingly, the control of the adjustable roll stabilizer 1 includes the so-called system theoretical torque as an input variable. Here, the system theoretical torque is a torque M preset by the vehicle and acting around the rotation axis 3. 系统 (see Figure 1) corresponding variable, which torque should be supported by the adjustable roll stabilizer 1 on the level of the actuator, so that this torque is exerted on the actuator 2 (comprising the electric motor 4 and the transmission 5) in a rotational direction around the rotational axis 3. By jointly acting kinematically on the vehicle structure 10 by the adjustable roll stabilizer 1, the wheel suspensions 7a, 7b, 8a, 8b, 9a, 9b and the connecting elements 11a, 11b, the adjustable roll stabilizer 1 thus supports (on the level of the vehicle) a roll moment M Figure 1 , which extends around the longitudinal extension of the vehicle 侧倾 .

[0031] The system theoretical torque is converted into a torque request-specific twist angle by means of a known system stiffness, which is composed of individual stiffnesses, in particular of the stiffness of the stabilizer itself (stabilizer section, transmission, housing, possibly decoupling element, swing strut, stabilizer bearing, etc.).

[0032] At the same time, variables for compensating disturbances are incorporated into the control of the adjustable roll stabilizer. For this purpose, wheel movement data in the form of height signals (detected by height sensors assigned to the wheels) and a characteristic table for the decoupling angle (with previously calculated data specific to the vehicle) are used to determine a so-called "zero torque angle", which corresponds to the external twist angle of the adjustable roll stabilizer (for example due to road unevenness) and which possibly causes no torque on the actuator of the adjustable roll stabilizer. The two angles calculated in this way, i.e. the torque request-specific twist angle and the zero torque angle, are then added to the theoretical angle.

[0033] The theoretical angle is then delivered to a cascaded orientation-rotational speed controller. This orientation-rotational speed controller contains a position controller, which calculates a theoretical rotational speed from the obtained theoretical angle (further taking into account the feedback signal of the motor), which is in turn delivered to a rotational speed controller. The rotational speed controller calculates a motor theoretical torque for actuating the electric motor on the basis of the theoretical rotational speed and the feedback (rotational speed) from the electric motor. The motor theoretical torque is in turn delivered to a field-oriented control device, which in turn actuates the electric motor 4 of the actuator 2 taking into account the feedback signal of the electric motor. The motor output torque generated by the electric motor 4 is now (mechanically) converted into a system torque by means of the transmission 5 (a multi-stage planetary transmission), which acts between the stabilizer sections (see Figure 1 Fig. 6a and 6b).

[0034] The control diagram shown in Figure 2 is advantageously applied to a vehicle as in Figure 1Adjustable roll stabilizer 1. Under the control principle described there, the system theoretical torque obtained is converted into a theoretical angle by means of the system stiffness, from which a motor theoretical torque is calculated by means of an azimuth-rotational speed controller, where a corresponding motor current is applied to the motor

[0035] By means of Figure 1 and Figure 2 The control strategy described by way of example with the adjustable roll stabilizer 1 is initially first of all related to the vehicle axle. The system theoretical torque obtained as an input signal is thus a variable which is preset for the respective vehicle axle or associated adjustable roll stabilizer. This variable corresponds to the (vehicle axle-related) roll torque M 侧倾 which the vehicle axle concerned is to support. If the motor vehicle is equipped with an adjustable roll stabilizer, preferably two adjustable roll stabilizers (front axle and rear axle), it is possible within the scope of active roll stabilization to distribute the total roll torque which the motor vehicle as a whole is to support over the two vehicle axles between the front axle and the rear axle. This is done at vehicle level in such a way that for each (existing) adjustable roll stabilizer a corresponding system theoretical torque, i.e. a system torque M 系统 which is to be supported by the respective actuator 2, is preset.

[0036] Depending on the distribution of the roll torque to be supported by each vehicle axle, a so-called roll torque distribution β is derived for the motor vehicle, which is calculated from the ratio of the roll torque supported by the front axle to the total roll torque supported by the motor vehicle as a whole.

[0037] In a manner known per se, when the total support torque has too large a proportion applied to the front axle, the motor vehicle in principle tends to understeer; when the total support torque has too large a proportion falling on the rear axle, the motor vehicle in principle tends to oversteer.

[0038] It is proposed within the scope of the invention to check the system theoretical torque preset for the adjustable roll stabilizer for the admissibility in terms of the vehicle admissible roll torque distribution β.

[0039] In this connection, first of all reference should be made to Figure 3 which shows an exemplary illustration of two limit curves for the roll torque distribution. The diagram contains an upper limit curve (dashed line) and a lower limit curve (solid line) for the roll torque distribution β. The lower limit curve for the roll torque distribution β is derived depending on the vehicle speed, which first of all rises sharply, then remains constant and thereafter continues to rise linearly from above the average speed. The upper limit curve extends constantly (in the case of positive vehicle speed), the value of which significantly exceeds 50%.

[0040] In a dual-axle motor vehicle (the calculations for this dual-axle motor vehicle have already been made), Figure 3 In the limit curves shown, when the actual roll moment distribution β in a motor vehicle is higher than the upper limit curve, the vehicle is theoretically prone to understeer. On the other hand, when the actual roll moment distribution β in a motor vehicle (which in this case depends on vehicle speed) is lower than the corresponding value of the lower limit curve, the motor vehicle is theoretically prone to oversteer. Above or below the limit curves, there is a tendency for either oversteer or understeer, and in these cases, at least in some driving situations, the vehicle may become uncontrollable for inexperienced drivers.

[0041] The roll moment distribution β is explicitly calculated as follows:

[0042] β = (Front axle support torque) / (Front axle support torque + Rear axle support torque).

[0043] To check the pre-set theoretical torque of the system on the vehicle side (see also...) Figure 2 Regarding the tolerance of the permissible roll moment distribution β for a motor vehicle, this invention proposes: firstly, for a predetermined theoretical system torque, calculate the resulting roll moment distribution β, and then perform a comparison to determine whether the calculated roll moment distribution β is within the permissible range, wherein the permissible range is specifically understood to be: the calculated roll moment distribution β is lower than the upper limit curve for roll moment distribution and higher than the lower limit curve for roll moment distribution (see [reference]). Figure 3 In situations where there is a lack of tolerance, i.e. when the roll moment distribution β is outside the permissible range, more erroneous measures should be taken, especially the proposal to shut down the roll stabilizers present on the motor vehicle.

[0044] To elaborate further, please refer to [the relevant source]. Figure 4 This diagram illustrates a schematic overview of roll stabilization in a two-axle vehicle, taking into account roll moment distribution. The control diagrams for the front axle (VA) and (below) the rear axle (HA) are schematically and simplified, represented by the upper and lower rectangles, respectively. In principle, the controls used for the front and rear axles are the same. Therefore, to avoid repetition, only the control of the front axle will be discussed first.

[0045] In most cases, Figure 4 The control shown, based on the rectangle above, for the front axle (VA) is already achieved using... Figure 2 The control described is presented in a simplified form for illustrative purposes. The control comprises a reference variable control (VA) and a disturbance variable control (VA), both incorporated into the calculation of the VA at the theoretical position. Figure 4 The theoretical position VA represented in the figure corresponds to the position calculated using the method already known.Figure 2 The calculation of the "theoretical angle" is based on (on the one hand) the system theoretical torque (reference variable control) and the wheel movement data (disturbance variable control) according to Figure 4 , followed by the yaw-rotational speed control VA and finally the motor control VA (in each case in combination with Figure 2 , which is described in more detail).

[0046] In addition and thus differently from the control strategy shown in Figure 2 , within the scope of the present application the theoretically set torque VA (system theoretical torque) by the reference variable control VA according to Figure 4 is not only included in the theoretical position calculation VA, but also in the "roll torque distribution safeguard VA". In other words, the system theoretical torque set as a reference variable is hereby included in the check with regard to the roll torque distribution of the motor vehicle.

[0047] As can also be derived from Figure 4 , a further variable is also taken into account to check the admissibility of the set system theoretical torque ("roll torque distribution safeguard VA"). Here, the further variable is the theoretical support torque HA, which is the system theoretical torque of the rear axle. This is achieved in that the system theoretical torque set by the reference variable control HA (of the rear axle) is transmitted to the roll torque distribution safeguard VA via a corresponding communication channel (for example CAN bus).

[0048] On the basis of the system theoretical torque of the front axle and the rear axle, within the scope of the roll torque distribution safeguard VA - taking into account the time delay (caused by the transmission) - the roll torque distribution β applied at the time of the transmission of the information can be calculated. The calculated roll torque distribution β is then compared with the upper and lower limit curves for the roll torque distribution (see Figure 3 ). When the calculated roll torque distribution β is below the upper limit curve for the roll torque distribution and above the lower limit curve for the roll torque distribution, there is an admissible roll torque distribution.

[0049] The control schematic of the adjustable roll stabilizer of the rear axle is in principle identical to that of the adjustable roll stabilizer of the front axle. A roll torque distribution safeguard HA is likewise provided, which functions in the same way as the roll torque distribution safeguard VA of the front axle, however, the corresponding (inverted) theoretical support torque VA, i.e. the system theoretical torque of the front axle, is called up. Furthermore, it functions in the same way as on the front axle, so that the explanations relating thereto are omitted in order to avoid repetition.

[0050] If, as part of the checking of the admissibility of the roll moment distribution for the continuously maximum permissible fault tolerance time, it is determined that a value outside the permissible limit is present, the entire system is switched to a safe state, in particular to cause the shut-off of the actuators of the two adjustable roll stabilizers (on the front axle and on the rear axle).

[0051] List of reference signs

[0052] 1 adjustable roll stabilizer

[0053] 2 actuator

[0054] 3 rotation axis

[0055] 4 electric motor

[0056] 5 multi-stage planetary transmission

[0057] 6a, 6b left (or right) stabilizer section

[0058] 7a, 7b left (or right) vehicle wheel

[0059] 8a, 8b left (or right) steering mechanism

[0060] 9a, 9b left (or right) swing strut

[0061] 10 vehicle structure

[0062] 11a, 11b left (or right) stabilizer support

[0063] 12a, 12b height sensor of the left (or right) vehicle wheel

[0064] 13 rotational speed sensor

[0065] 20 kinematic mechanism

[0066] z 7a , z 7b height of the left (or right) vehicle wheel

[0067] M 侧倾 roll moment (related to the axle)

[0068] M 系统 system moment

[0069] n motor rotational speed

[0070] HA rear axle

[0071] VA front axle

[0072] a system angle

[0073] b roll moment distribution

Claims

1. Method for operating an adjustable roll stabilizer (1) of a motor vehicle, the adjustable roll stabilizer (1) having an actuator (2) which is rotatable relative to a rotation axis (3) in order to twist two stabilizer sections (6a, 6b) connected with the actuator relative to one another about the rotation axis (3), wherein the stabilizer sections (6a, 6b) are respectively coupled with a wheel suspension (7a, 7b, 8a, 8b, 9a, 9b) radially away from the rotation axis (3), wherein the actuator (2) is actuated on the basis of a system theoretical torque which is predefined on the vehicle side, and wherein a check of the admissibility of the predefined system theoretical torque with regard to an admissible roll torque distribution (β) of the motor vehicle is effected by the fact that the roll torque distribution (β) resulting therefrom is calculated for the predefined system theoretical torque and a comparison is carried out as to whether the roll torque distribution (β) lies within an admissible range, the admissible range of the roll torque distribution (β) being predefined by at least one limit curve which depends on the vehicle speed.

2. The method of claim 1, wherein, The admissible range of the roll torque distribution (β) is limited by an upper limit curve and a lower limit curve, wherein there is an admissible roll torque distribution when the calculated roll torque distribution (β) is below the upper limit curve for the roll torque distribution and above the lower limit curve for the roll torque distribution.

3. The method according to one of the preceding claims, characterized in that, In the case of a lack of admissibility, i.e. when the predefined system theoretical torque for the adjustable roll stabilizer (1) leads to a roll torque distribution (β) which is outside the admissible range, a further measure is initiated.

4. The method of claim 3, wherein, The further measure involves a switchover to a safety state.

5. The method of claim 4, wherein, The further measure involves switching off the adjustable roll stabilizer (1) of the motor vehicle.

6. The method of claim 1, wherein, For checking the admissibility of the predefined system theoretical torque, in addition to the predefined system theoretical torque for the adjustable roll stabilizer (1), a predefined system theoretical torque for a further adjustable roll stabilizer of the motor vehicle is also taken into account.

7. The method of claim 1, wherein, For calculating the roll torque distribution (β), in addition to the predefined system theoretical torque for the adjustable roll stabilizer (1), a predefined system theoretical torque for a further adjustable roll stabilizer of the motor vehicle is also taken into account.

8. The method of claim 1, wherein, The roll torque distribution (β) is calculated from the ratio of the roll torque supported by a first vehicle axle (VA) to the roll torque supported overall by the motor vehicle.

9. The method of claim 8, wherein, The roll torque supported overall on the motor vehicle is calculated from the sum of the roll torque supported by the first vehicle axle (VA) and the roll torque supported by a second vehicle axle (HA).

10. The method of claim 1, wherein, The actuator is actuated on the basis of the system theoretical torque in such a way that the system theoretical torque is taken into account for determining a theoretical angle, from which a motor theoretical torque for actuating a motor (4) of the actuator (2) is calculated by means of an orientation-rotational speed controller.

11. The method of claim 1, wherein, using the method to operate the two adjustable roll stabilizers of the motor vehicle in such a way that the actuator of any one of the two adjustable roll stabilizers (1) is operated on the basis of a system theoretical torque which is preset for the respective axle (VA, HA) at the vehicle side, wherein the preset system theoretical torque is checked independently for admissibility in terms of the admissible roll torque distribution (β) of the motor vehicle.

12. A twin-axle motor vehicle having two adjustable roll stabilizers (1) which are suitable for carrying out the method according to one of the preceding claims and one of the two adjustable roll stabilizers (1) is assigned to the front axle (VA) and the other adjustable roll stabilizer (1) is assigned to the rear axle (HA), wherein each of the two adjustable roll stabilizers (1) is operable in dependence on a reference variable in the form of a system theoretical axle-related torque which is preset at the vehicle side, wherein each of the adjustable roll stabilizers (1) is assigned a device for checking the admissibility of the axle-related system theoretical torque in terms of the admissible roll torque distribution (β) of the motor vehicle.

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