Device and Method for Operating a Roll Stabilization System

Please substitute the new Abstract submitted herewith for the original Abstract: A device for operating an active roll stabilization system of a vehicle is described, which active roll stabilization system has a roll stabilizer on at least one axle of the vehicle, which roll stabilizer is configured to adjust, by use of an electrically operated actuator, a degree of twist between lever arms of the roll stabilizer which act on different sides of the axle, in order to counteract a roll movement of the vehicle. The device is set up to determine which operating mode of a plurality of different operating modes of the roll stabilization system has been selected by a user of the vehicle. Further, the device is set up to operate the actuator as a generator, in order to recuperate electrical energy from a roll movement of the vehicle and/or from a roadway-induced movement of the vehicle, in a manner dependent on the selected operating mode.

BACKGROUND AND SUMMARY

The invention relates to a device and to a corresponding method for operating a roll stabilization system, in particular in order to increase the comfort and/or the energy efficiency of a vehicle.

A multitrack vehicle can have an active, in particular an electromechanical, roll stabilization system designed to reduce and/or compensate rolling movements of the vehicle. The vehicle can be e.g. an ICE (internal combustion engine), an MHEV (Mild-Hybrid Electrical Vehicle), a PHEV (Plugin-Hybrid Electrical Vehicle) or a BEV (Battery Electrical Vehicle). By reducing the rolling movements, the comfort of the vehicle can be increased and/or the driving behavior of the vehicle can be improved.

The present document is concerned with the technical problem of enabling a flexible and/or optimized compromise between comfort and energy efficiency of a vehicle with an active roll stabilization system.

The object is achieved by each of the independent claims. Advantageous embodiments are described inter alia in the dependent claims. It is pointed out that additional features of a patent claim dependent on an independent patent claim can form an invention without the features of the independent patent claim, or just in combination with some of the features of the independent patent claim, which stands on its own and is independent of the combination of all the features of the independent patent claim and which can be made the subject of an independent claim, a divisional application or a subsequent application. This applies in the same way to technical aspects or teachings described in the description, which can form an invention that is independent of the features of the independent patent claims.

According to one aspect, a device for operating an active roll stabilization system of a (motor) vehicle is described. On at least one axle (e.g. on the rear axle and/or on the front axle) of the vehicle, the roll stabilization system of the vehicle comprises a (electromechanical) roll stabilizer designed to rotate lever arms of the roll stabilizer, which act on different sides of the axle, in opposite directions by means of an electrically operated actuator (e.g. an electric motor) in order to counteract a rolling movement of the vehicle. In other words, the actuator of the roll stabilizer may be configured to adjust, modify and/or control a rotation of the lever arms of the roll stabilizer.

The device is configured to determine which operating mode from a plurality of different operating modes of the roll stabilization system was selected by a user (in particular the driver) of the vehicle. The plurality of different operating modes can include e.g. a compensation mode (which e.g. is directed primarily to roll stabilization of the vehicle) and a recovery mode (which e.g. is directed primarily to the recovery of electrical energy from rolling movements of the vehicle). In this respect, the number of different operating modes can be high enough that intermediate operating modes between a (pure) compensation mode and a (primary and/or pure) recovery mode can be selected and/or adjusted virtually steplessly.

The vehicle may comprise a user interface which enables the user of the vehicle to make one or more user inputs, in particular by actuating an operator control element of the user interface. For example, the user interface can comprise an operator control element, by means of which one of the different operating modes of the roll stabilization system can be selected. In this respect, one of the operating modes can be selected optionally implicitly in the context of selecting a driving mode (e.g. a comfort mode or a sport mode or an energy saving mode). In other words, one of the operating modes can be selected by actuating a driving experience switch. The device may therefore be configured to determine, on the basis of a user input from the user, which operating mode was selected by the user of the vehicle.

The device is also configured to operate the actuator at least partially and/or temporarily as a generator depending on the selected operating mode, in order to recover electrical energy from a rolling movement of the vehicle and/or from a roadway-induced movement of the vehicle (in particular from a roadway-induced movement of wheels of the vehicle). In particular, the device may be configured to operate the actuator of the at least one roll stabilizer (passively or as a generator) to recover electrical energy from a rolling movement or (actively or as a motor) to compensate the rolling movement of the vehicle depending on the selected operating mode.

It is therefore possible to enable selective use (that can be chosen by a user) of a roll stabilizer for the purpose of roll stabilization or recovery of electrical energy. Therefore, an optimized compromise between comfort and energy efficiency of a vehicle can be enabled.

The compensation mode may be designed in such a way that the actuator of the at least one roll stabilizer is operated actively (i.e. as a motor) more frequently, for a longer period of time, and/or more strongly or intensively, at least on average over time, in the compensation mode than in the recovery mode in order to counteract rolling movements of the vehicle. As an alternative or in addition, the recovery mode may be designed in such a way that the actuator is operated (as a generator) more frequently and/or for a longer period of time and/or more intensively, at least on average over time, in the recovery mode than in the compensation mode in order to recover electrical energy from rolling movements of the vehicle.

The different operating modes, in particular the recovery mode and the compensation mode, can therefore differ in terms of the intensity of the stabilization performed by the roll stabilizer. In this respect, the energy balance of the vehicle can be improved by reducing the extent of the stabilization (in the recovery mode) (even when the actuator functions as a motor over the same period of time in the recovery mode and in the compensation mode). The different operating modes may, if appropriate, have different ways of triggering the actuator (e.g. a different parametrization of the motor regulator).

As an alternative or in addition, the recovery mode may be designed in such a way that the actuator on average over time generates more electrical energy than it consumes for the purpose of roll stabilization of the vehicle. By contrast, the compensation mode may be designed in such a way that the actuator on average over time generates less electrical energy than it consumes for the purpose of roll stabilization of the vehicle.

By providing operating modes that are complementary in this way, it is particularly effectively made possible for the user to achieve an optimized compromise between comfort and energy efficiency of the vehicle.

The one or more operating modes of the roll stabilization system may each establish one or more stabilization driving situations of the vehicle, in which the actuator is operated actively for the purpose of roll stabilization of the vehicle. Furthermore, the one or more operating modes of the roll stabilization system may each establish one or more recovery driving situations of the vehicle, in which the actuator is operated as a generator for the purpose of recovering electrical energy from rolling movements of the vehicle.

Exemplary driving situations in this context are a cornering maneuver or straight-ahead travel. A driving situation may be defined by one or more driving parameters of the vehicle. Exemplary driving parameters are: the speed of the vehicle, the acceleration of the vehicle, the steering angle of the steering mechanism of the vehicle, the steering angle speed of the steering mechanism of the vehicle, etc. The different driving situations may be defined by different combinations of parameter values for the one or more abovementioned driving parameters.

The different operating modes of the roll stabilization system can differ at least in part with respect to the establishment of the one or more stabilization driving situations and/or the one or more recovery driving situations. By establishing specific driving situations for the operation of the actuator of a roll stabilizer as a motor or as a generator, it is possible to enable reliable switching between the different operating modes.

The device may be configured to ascertain driving data relating to the current journey of the vehicle. The driving data may indicate e.g. the steering angle and/or the steering angle speed of the steering mechanism of the vehicle. In particular, the driving data may indicate current parameter values for one or more of the abovementioned driving parameters.

Furthermore, the device may be configured to ascertain, on the basis of the driving data and on the basis of the selected operating mode, whether (at a current point in time) a stabilization driving situation or a recovery driving situation of the vehicle is present. The actuator of the at least one roll stabilizer can then be operated depending on whether a stabilization driving situation or a recovery driving situation is present. In particular, the actuator can be utilized for the purpose of roll stabilization when a stabilization driving situation is present. By contrast, the actuator can be utilized to recover electrical energy when a recovery driving situation is present. It is therefore particularly reliably possible to provide an optimized compromise between comfort and energy efficiency.

The compensation mode and the recovery mode can be defined in such a way that at least one driving situation, which is specified as stabilization driving situation in the compensation mode, is specified as recovery driving situation in the recovery mode. In this respect, in the recovery mode, in particular straight-ahead travel of the vehicle, in which the steering angle and/or the steering angle speed is smaller in terms of magnitude than a predefined threshold value, can be a recovery driving situation (whereas this straight-ahead travel constitutes a stabilization driving situation in the compensation mode). In this context, during straight-ahead travel, the roll stabilizer typically primarily corrects roadway stimuli (i.e. regulation of external disturbances).

Optionally, the recovery of electrical energy during straight-ahead travel of the vehicle may be restricted. By contrast, during a cornering maneuver, roll stabilization may (at least primarily) continue to effected. The use of the at least one roll stabilizer for recovery purposes can therefore be restricted, if appropriate, to limiting the comfort (whereas drive-stabilizing measures are continued). As an alternative, the rolling dynamics of the vehicle imposed during a cornering maneuver can (at least partially), if appropriate, be used to recover electrical energy.

The electrical on-board power system of the vehicle may comprise a first electrical subsystem having a first system voltage (e.g. a 48 V system) and a second electrical subsystem having a second system voltage (e.g. a 12 V system). The first and the second system voltage may in this case be the same (e.g. each 12 V) or different. The actuator of the at least one roll stabilizer may be arranged in the first subsystem. Furthermore, the first subsystem may comprise an energy store (e.g. an electrochemical energy store, for instance a lithium-ion battery) for storing electrical energy for the operation of the actuator and/or for buffering current and/or voltage peaks while the actuator is being operated as a motor or as a generator.

The device may be configured to detect the recovery of the electrical energy by the actuator of the at least one roll stabilizer. This may be detected e.g. on the basis of the selected operating mode and/or on the basis of the current driving situation.

Furthermore, the device may be configured to transfer electrical energy from the first subsystem to the second subsystem in response to the detected recovery and/or in response to the detected voltage difference between the two subsystems, in particular by operating a (bidirectional) DC voltage converter between the first subsystem and the second subsystem. The electrical energy recovered can therefore be used to operate a second electrical subsystem of the vehicle. In this way, the energy efficiency of the vehicle can be increased further.

The device may be configured to determine the inability of the energy store to fully take up the electrical energy recovered by the actuator of the at least one roll stabilizer, in particular owing to a delimited charging power of the energy store and/or owing to a delimited storage capacity of the energy store. For example, it can be identified that the recovered electrical power is greater than the charging power of the energy store of the first subsystem. As an alternative or in addition, it can be identified that the state of charge of the energy store of the first subsystem is high enough that the recovered electrical energy cannot be (fully) taken up by the energy store.

The device may be configured (optionally only) in response thereto to operate the DC voltage converter between the first subsystem and the second subsystem in order to transfer electrical energy from the first subsystem to the second subsystem. In this way, it is possible to have the effect that the recovered electrical energy is utilized as fully as possible by the vehicle, with the result that the energy efficiency of the vehicle can be further improved.

According to a further aspect, a (road) motor vehicle (in particular a passenger car or a truck or a bus) comprising the device described in the present document is described.

According to a further aspect, what is described is a (computer-implemented) method for operating an active roll stabilization system of a vehicle, which, on at least one axle of the vehicle, comprises a roll stabilizer designed to adjust (in particular to control or to regulate to a determined setpoint value) a rotation between lever arms of the roll stabilizer, which act on different sides of the axle, by means of an electrically operated actuator, in order to counteract a rolling movement of the vehicle.

The method comprises determining an operating mode from a plurality of different operating modes of the roll stabilization system that was selected by a user of the vehicle. The method also comprises operating the actuator as a motor and/or as a generator, depending on the operating mode selected. In the process, depending on the operating mode selected, electrical energy can be at least partially and/or temporarily recovered from a rolling movement of the vehicle and/or from roadway-induced movements (of the axle) of the vehicle.

According to a further aspect, a software (SW) program is described. The SW program may be configured to be executed on at least one processor (e.g. on one or more controllers of a vehicle), and to carry out the method described in the present document as a result.

According to a further aspect, a storage medium is described. The storage medium may comprise a SW program which is configured to be executed on a processor, and to carry out the method described in the present document as a result.

It should be noted that the methods, devices and systems described in the present document can be used both individually and in combination with other methods, devices and systems described in the present document. Furthermore, any aspects of the methods, devices and systems described in the present document may be combined with one another in a wide variety of ways. In particular, the features of the claims may be combined with one another in a wide variety of ways.

The invention is also described in more detail with reference to exemplary embodiments.

DETAILED DESCRIPTION OF THE DRAWINGS

As set out in the introduction, the present document is concerned with increasing the energy efficiency of a vehicle having a roll stabilization system. In this context, Figure la shows exemplary components of a vehicle100. The vehicle100comprises a drive motor101(e.g. an internal combustion engine and/or an electric machine) which is designed to drive at least one axle121(e.g. the rear axle) of the vehicle100. The vehicle100typically comprises a further axle122(e.g. the front axle). Wheels109are arranged on the axles121,122of the vehicle100.

The (two-track) vehicle100illustrated inFIG.1comprises an active (roll) stabilizer130for each axle121,122. The lever arms132of a stabilizer130are each attached to the chassis of the vehicle100via a bearing131. In this context, the lever arms132each act (indirectly) on the wheel carriers105of a wheel109. A lever arm132may act indirectly on the wheel carrier105of a wheel109, e.g. via a damper or a connecting rod.

In particular, a stabilizer130comprises a right-hand lever arm132for the right-hand wheel109and a left-hand lever arm132for the left-hand wheel109of an axle121,122. The two lever arms132of the stabilizer130may be rotated in opposite directions via an actuator133, which typically comprises an electric machine, in order to make forces that counteract a rolling movement act on the wheels109of an axle121,122.

The electrical energy for the operation of the actuator133of a stabilizer133can be drawn from an electrical energy store106. The operation of the actuator133can be controlled by at least one control unit (or by a triggering device)111, for instance by a central control unit and/or by multiple decentralized control units. In particular, regulation may be carried out in order to bring about a determined setpoint behavior of the vehicle100with respect to rolling movements.

FIG.1billustrates how a rolling movement of the vehicle100can be brought about owing to unevenness of the roadway150on which the vehicle100is traveling and/or owing to a cornering maneuver. The stabilizer130can make forces that counteract such a rolling movement act on the lever arms132by triggering the actuator133.

FIG.2shows an exemplary electrical on-board power system200of a vehicle100. The on-board power system200may comprise multiple subsystems210,220with different system voltages211,221. In particular, a first subsystem210(e.g. a 48 V system) may have a first system voltage211(e.g. 48 V), and a second subsystem 220 (e.g. a 12 V system) may have a second system voltage 221 (e.g. 12 V). The subsystems210,220may be connected to one another via a DC voltage converter201in order to enable the transfer of electrical energy between the subsystems210,220.

In an alternative scenario, both subsystems210,220may have the same system voltage211,221(e.g. 12 V). The subsystems210,220may be arranged in series. In this case, if appropriate, no DC voltage converter201is required between the subsystems210,220.

The one or more stabilizers130of the vehicle100may be arranged in the first subsystem210as electrical consumers212. An energy store of the first subsystem210may be used as energy store106for the one or more stabilizers130(e.g. a lithium-ion-based energy store). The second subsystem220may correspondingly comprise one or more electrical consumers222and/or an electrical energy store223.

The vehicle100may comprise a user interface (not illustrated) for a user, in particular for a driver, of the vehicle100. The user interface may comprise e.g. at least one operator control element enabling the user to select an operating mode135of the stabilization system of the vehicle100having the one or more stabilizers130. Exemplary operating modes135are a compensation mode, in which rolling movements of the vehicle100are compensated as comprehensively as possible by active engagement of the actuators133of the one or more stabilizers130; and a recovery mode, in which rolling movements of the vehicle100are compensated only to a reduced extent (compared to the compensation mode), but in which the actuators133of the one or more stabilizers130are operated at least temporarily as electrical generators, in order to generate electrical energy on the basis of the rolling movements of the vehicle100. In the process, the electrical energy recovered can be stored in the energy store106of the first subsystem210.

If appropriate, a multiplicity of different operating modes that enable e.g. (virtually) stepless adjustment between a compensation mode (with stabilization which is as comprehensive as possible) and a recovery mode (with recovery which is as comprehensive as possible) can be enabled and/or selected and/or adjusted.

The control unit111may be configured to determine in which operating mode the (roll) stabilization system of the vehicle100is operated. The actuators133of the one or more stabilizers130may then be operated depending on the operating mode selected. In particular, the actuators133can be made to generate electrical energy on the basis of the rolling movement of the vehicle100when a determination has been made that the stabilization system should be operated in the recovery mode.

Furthermore, the control unit111may be configured (when the stabilization system is operated in the recovery mode) to operate the DC voltage converter201in such a way that electrical energy is transferred from the first subsystem210to the second subsystem220. Expressed generally, the at least one control unit111may be configured to bring about the transfer of electrical energy from the first subsystem210to the second subsystem220(when the stabilization system is operated in the recovery mode and/or when there is a voltage difference between the subsystems210,220).

This can be effected in particular when it is ascertained that the energy store106of the first subsystem210has a relatively high state of charge (e.g. a state of charge above a determined state-of-charge threshold value). In this way, the effect can reliably be brought about that excessive recovered electrical energy can be utilized for operating one or more electrical consumers222in the second subsystem220and/or for storage in the energy store223of the second subsystem220. This therefore brings about an increase in the energy efficiency of the vehicle100.

It is consequently possible to provide a recovery mode of the stabilization system of the vehicle100that has a positive energy balance (with the result that, on average over time, more electrical energy is generated by the actuators133of the one or more stabilizers130than is consumed by the actuators133for the purpose of roll stabilization). In this respect, the stabilization system may be operated e.g. in the 48 V on-board power system210of the vehicle100.

Excess energy from the recovery of the stabilization system can be transferred from the 48 V store106to the 12 V on-board power system220. The energy transferred can be utilized for 12 V consumers222. This means that less energy needs to be taken from a HV (high-voltage) on-board power system of the vehicle100and/or from a generator, thereby resulting in an increased range of the vehicle100and/or in a reduction of the (possibly electrical) energy consumption or CO2 emissions of the vehicle100.

During operation of the stabilization system, for example, the vehicle100can travel in the recovery mode along a roadway150with relatively large and/or a relatively large number of unevennesses. During the journey, electrical energy can be recovered by the one or more actuators133and stored in the (optional) 48 V store106. Excess energy can be transferred from the 48 V store106, e.g. via the (bidirectional) DC voltage converter201, to the 12 V on-board power system220. If appropriate, given a corresponding design of the converter201(with sufficiently high power dynamics), operation without a store106is enabled.

FIG.3shows a flow diagram of an exemplary (optionally computer-implemented) method300for operating an active roll stabilization system of a (motor) vehicle100. The method300can be carried out by a device or by a control unit111of the vehicle100.

On at least one axle121,122of the vehicle100, the roll stabilization system comprises a roll stabilizer130designed to rotate lever arms132of the roll stabilizer130, which act on different sides of the axle121,122, in different directions by means of an electrically operated actuator133(in particular by means of an electric machine or by means of an electric motor), in order to counteract a rolling movement of the vehicle100. The roll stabilization system may comprise a first roll stabilizer130for a first axle121, e.g. the rear axle, and a second roll stabilizer130for a second axle122, e.g. the front axle, of the vehicle100.

The method300comprises determining301which operating mode135from a plurality of different operating modes135of the roll stabilization system was selected by a user of the vehicle100. The operating mode135may have been selected e.g. via a user interface of the vehicle100. The roll stabilization system may be operated e.g. (as standard practice) in a compensation mode. Furthermore, the roll stabilization system can be operated in a recovery mode. In this respect, the recovery mode may be designed in such a way that, in this mode, the amount of electrical energy that can be recovered by the roll stabilization system can be increased (compared to the compensation mode). By contrast, the compensation mode may optionally have higher comfort with respect to the roll stabilization than the recovery mode. If appropriate, in the compensation mode there is no recovery at all of electrical energy by the roll stabilization system.

The method300also comprises operating302the actuator133of the at least one roll stabilizer130(as a motor and/or as a generator) depending on the selected operating mode135. In the process, the actuator133of the at least one roll stabilizer130can be utilized to recover electrical energy from a rolling movement of the vehicle100and/or from roadway-induced wheel movements. If appropriate, the actuator133(in a determined driving situation) can be operated in the compensation mode in such a way that no electrical energy is recovered by the actuator133(but, if appropriate, the actuator133is actively triggered for roll stabilization of the vehicle100). By contrast, the actuator133(in the determined driving situation) can be operated in the recovery mode in such a way that electrical energy is recovered by the actuator133(and the actuator133is not actively triggered, or is actively triggered only to a reduced extent compared to the compensation mode, for roll stabilization of the vehicle100).

The selective use of a roll stabilizer130for recovering electrical energy makes it possible to provide an optimized compromise between comfort and energy efficiency of a vehicle100.

The present invention is not restricted to the exemplary embodiments shown. In particular, it should be noted that the description and the figures are intended only to illustrate the principle of the proposed methods, devices and systems.