Method for operating a motor vehicle, computer program product, storage medium, computing device

Abstract

The invention relates to a method for operating a motor vehicle (1), wherein the motor vehicle (1) has at least one axle (2) with at least one wheel (3), wherein the wheel (3) is assigned an electric drive device (4) with a steerable first actuator assembly (5) having an electric machine (6), and wherein the wheel (3) is assigned a wheel brake device (7) with a steerable second actuator assembly (8), in particular with an electric machine assigned to a hydraulic pump and / or a hydraulic valve assembly. According to the invention, each actuator assembly (5, 8) is assigned at least one, in particular wheel-individual, slip limit value (λ Hyd,Vor , λ Elec,min , λ Rad,lim , λ Hyd ) and the actuator assemblies (5, 8) are steered in accordance with a pre-specified slip limit value (λ Hyd,Vor , λ Elec,min , λ Rad,lim , λ Hyd ) for meeting a braking request.

Description

Technical Field

[0001] The present invention relates to a method for operating a motor vehicle, wherein the motor vehicle includes at least one axle having at least one wheel, wherein the wheel is associated with an electric drive device having a controllable first actuator assembly having a motor, and wherein the wheel is associated with a hydraulic wheel braking device having a controllable second actuator assembly, particularly having a motor and / or hydraulic valve assembly associated with a hydraulic pump.

[0002] Furthermore, the present invention relates to a computer program product that, when executed on a computing device, performs the aforementioned method. Additionally, the present invention relates to a machine-readable storage medium having such a computer program product, and a computing device specifically designed to execute the computer program product or perform the aforementioned method. Background Technology

[0003] Motor vehicles equipped with hydraulic wheel braking devices and ride dynamics adjustment systems are known from the prior art. Modern ride dynamics adjustment systems typically include a ride dynamics controller and a brake hydraulic system. The brake hydraulic system is connected to the wheel brake cylinders of the wheel braking device via brake lines. The braking pressure in the wheel brake cylinders can be adjusted using various valves and a hydraulic pump.

[0004] For example, such a driving dynamics adjustment system is known from the applicant's published document DE 43 05 155 A1. It describes how the driving dynamics adjuster interacts with the brake hydraulic system. The driving dynamics adjuster is essentially composed of a yaw speed adjuster. This yaw speed adjuster obtains yaw speed signals, wheel speed signals used to form vehicle speed, steering angle signals, and lateral acceleration signals from a measurement data detection device. The yaw speed adjuster uses the measurement signals and a physical model of the vehicle's yaw motion to form a target yaw speed profile. Depending on driving conditions, the yaw speed adjuster generates hydraulic braking intervention to stabilize the vehicle. To this end, the target wheel slip ratio is increased or decreased by the lower-level wheel adjuster, or the target wheel braking pressure is changed by altering the valve opening time of the output brake hydraulic system.

[0005] Through the continuous development of ride dynamics systems, additional functions have emerged besides yaw speed regulators. These include rollover prevention, also known as Roll Over Mitigation (ROM) or Roll Movement Intervention (RMI), and trailer stabilization, also known as Trailer Sway Mitigation (TSM). All of these functions now fall under the lateral dynamic stabilization function of ride dynamics systems, and all share the common feature of utilizing a brake hydraulic system to generate hydraulic braking intervention to stabilize the vehicle. The increasing electrification of vehicles has led to drive schemes with individual electric motors for each wheel. These motors can generate not only driving torque but also braking torque. If now both actuators—hydraulic wheel brakes and electric drive motors—are mounted on one wheel of the vehicle, both can be used by the lateral dynamic stabilization function to generate braking intervention while stabilizing the vehicle. Summary of the Invention

[0006] The method according to the invention, having the features of claim 1, is characterized in that each actuator assembly is associated with at least one, particularly wheel-specific, slip ratio extreme value, and the actuator assembly is manipulated according to a pre-given slip ratio extreme value to satisfy a braking request. As described at the outset, driving dynamics adjustment systems typically use hydraulic wheel brakes to stabilize the vehicle. However, other braking variations, such as electromechanical brakes, can also be used. If the vehicle has another actuator on the corresponding wheel, currently an electric drive motor, as configured according to the invention, the stabilization task can be solved by optimized manipulation of the resulting wheel combination actuator, including the wheel brake and the drive motor. This advantageously ensures that both actuator assemblies are optimally incorporated and used in driving dynamics adjustment within the scope of slip adjustment to satisfy the braking request. The braking request is detected and / or sought, particularly by means of sensor assemblies, and pre-given and / or received by actuation and / or control devices. The invention provides in this respect a manipulation strategy in which two actuator assemblies are optimally manipulated jointly to generate braking torque on the corresponding wheel. This relates particularly to the distribution of braking torque to hydraulic and electric braking torques and the necessary monitoring of wheel slip ratio. Specifically regarding wheel slip ratio monitoring, the invention demonstrates a possibility of how this task can be accomplished by a lower-level wheel adjuster via, in particular, a hydraulic brake, and by a speed regulator via an electric drive motor. For this purpose, slip ratio extrema set according to the invention are used. It has been noted purely precautionarily that the numbering of the slip ratio extrema used below is for distinction only, not for priority or pre-given information, and does not imply a necessary correlation between the extrema. According to the invention, only two distinct slip ratio extrema are required, one at least assigned to the first actuator assembly and the other at least assigned to the second actuator assembly, so that it can be reliably determined which, when, and how of the two actuator assemblies will be manipulated and used within the scope of the method according to the invention. For example, the extrema described below as the third and fourth slip ratio extrema are used as a minimum prerequisite for this purpose. This results in the priority of the first actuator assembly, such that the braking torque is preferably provided and regulated as primarily as possible, especially solely by means of the first actuator assembly. The resulting sequence of braking torque distribution, which is described in more detail below by example, has advantages in terms of both comfort and the timing of vehicle stability. Control of the electric drive motor can begin earlier and occur in the area of ​​vehicle motion, still outside the areas of lateral dynamics (yaw rate adjustment) and rollover criticality (rollover prevention). From a hydraulic perspective, these areas can be disregarded in terms of driving comfort because noise always occurs when operating hydraulic brakes due to the hydraulic pump and valve switching within the brake hydraulic system. The driver's continued perception of lateral dynamic stabilization in a relatively non-critical area of ​​vehicle motion significantly reduces driving comfort.Another advantage of prioritizing the use of the first actuator assembly is improved adjustment quality when regulating wheel slip ratio. For example, the high cycle time (especially 1 ms) for motor speed regulation enables better wheel slip regulation precisely within the unstable slip region of the wheel. This not only benefits yaw rate regulation but also helps prevent rollover, which is significantly more frequently exposed to strong vehicle body movements. This generates strong wheel load fluctuations, which in turn strongly influence wheel slip behavior. In summary, the advantages of the scheme according to the invention, which controls the wheel combination actuators according to slip ratio values, are: optimally distributing the braking torque share, particularly the hydraulic brakes and electric drive motor, to improve comfort and vehicle stability at certain points, and improving wheel slip regulation quality, as this is preferentially achieved through speed regulation of the electric drive motor. The use of specific slip ratio extremes for the corresponding actuators according to the invention constitutes a particularly advantageous, simple, and elegant solution for robustly achieving this priority.

[0007] According to a preferred extension of the invention, at least one slip ratio extreme value is pre-given based on the performance of the corresponding actuator assembly and / or the driving mode of the vehicle, particularly including comfort mode and / or sport mode. This performance-related and / or mode-related pre-given value of the corresponding slip ratio extreme value advantageously ensures that the corresponding slip ratio extreme value is optimally adapted to the health state of the corresponding actuator assembly and / or the driving behavior desired by the corresponding driver. For example, the corresponding slip ratio extreme value is selected such that when the performance of one actuator assembly deteriorates, the corresponding other actuator assembly assumes a larger share of the braking torque to meet the braking request. Similarly, for example, in sport mode, a higher slip ratio extreme value is pre-given or allows for a higher wheel slip ratio than in comfort mode, for example, before corresponding active slip adjustment. In particular, at least one slip ratio extreme value is determined to have a pre-given safe distance from maximum performance and / or within a specific range of maximum performance, such as up to 50%, 75%, or 90% of maximum performance, so as not to overload the actuator assembly.

[0008] Particularly preferably, the actual slip ratio of the wheel is determined, and the first actuator assembly is initially manipulated solely based on this actual slip ratio, particularly by adjusting the motor speed, to generate the electric braking torque. This manipulation provides the advantage of preferential use of the first actuator assembly. Specifically, the braking torque required to meet the braking demand is initially provided solely by the first actuator assembly, particularly by operating the motor in generator or energy recovery operation. The second actuator assembly is only engaged as needed.

[0009] According to a preferred extension of the invention, a first slip ratio extreme value is pre-defined and assigned to the second actuator assembly, and when the actual slip ratio value at least reaches, and especially exceeds, the first slip ratio extreme value, the motor controlling the second actuator assembly, especially the motor assigned to the hydraulic pump, is activated, in addition to pre-filling the hydraulic circuit of the wheel braking device. By appropriately pre-defining and using the first slip ratio extreme value, it is advantageously ensured that the second actuator assembly is ready in a timely manner to generate braking torque, for example, when the actual slip ratio value further increases. In this respect, the reaction time for controlling the second actuator assembly is advantageously further reduced. However, this is not strictly necessary for the method according to the invention.

[0010] Particularly preferably, a second slip ratio extreme value is pre-defined and assigned to the second actuator assembly, wherein the second slip ratio extreme value is particularly greater than the first slip ratio extreme value, and the second actuator assembly is operated to generate additional hydraulic braking torque when the actual slip ratio value at least reaches, and particularly exceeds, the second slip ratio extreme value. By appropriately pre-defining and using the second slip ratio extreme value, the advantage of reliably engaging the second actuator assembly in slip conditions defined by this extreme value to assist the first actuator assembly when a braking request is met is obtained. The second slip ratio extreme value is determined, for example, based on the performance of the first actuator assembly to ensure that the first actuator is not overloaded by timely engagement of the second actuator assembly. The slip ratio extreme value determines, in this respect, which share of braking torque is provided by the first actuator assembly or its motor. Here, the slip ratio extreme value also defines an upper limit for the braking torque. Only the share of braking torque exceeding this limit is provided by the second actuator assembly and thus the hydraulic wheel braking device.

[0011] According to a preferred extension of the invention, a third slip ratio extreme value is pre-defined, particularly in the unstable region of the wheel slip curve, and assigned to the first actuator assembly. This third slip ratio extreme value is particularly greater than the first and / or second slip ratio extreme values. When the actual slip ratio value at least reaches, and particularly exceeds, the third slip ratio extreme value, the first actuator assembly is manipulated to maintain the third slip ratio extreme value, particularly to reduce the actual slip ratio value to the third slip ratio extreme value. The corresponding pre-defined and used third slip ratio extreme value advantageously ensures that the wheel slip ratio is regulated by means of the first actuator assembly. If the braking torque share provided by the two actuator assemblies results in a correspondingly high wheel slip ratio, an attempt is made to maintain the wheel at a desired wheel slip ratio by means of the first actuator assembly, particularly by pre-defining the motor speed, when the corresponding third slip ratio extreme value is exceeded. In particular, this desired wheel slip ratio, characterized by the third slip ratio extreme value, corresponds to the optimal wheel slip ratio for satisfying the braking request.

[0012] Particularly preferably, a maximum speed limit is preset for the motor of the first actuator assembly based on a third slip ratio limit, and the motor is controlled by speed regulation based on the speed limit. This speed regulation provides the advantage of particularly precise adjustment of the wheel slip ratio.

[0013] According to a preferred extension of the invention, a fourth slip ratio extreme value is pre-defined and assigned to the second actuator assembly, wherein the fourth slip ratio extreme value is particularly greater than the first, second, and / or third slip ratio extreme values, and when the actual slip ratio value at least reaches, and particularly exceeds, the fourth slip ratio extreme value, the second actuator assembly, particularly the hydraulic valve assembly, is actuated to maintain the fourth slip ratio extreme value, and particularly to reduce the actual slip ratio value to the fourth slip ratio extreme value. By appropriately pre-defining and using the fourth slip ratio extreme value, it is advantageously ensured that if the first actuator assembly fails to maintain the wheel slip ratio near its assigned slip ratio extreme value, the second actuator assembly performs auxiliary adjustments to ensure driving safety at all times. In this respect, the second actuator assembly adjusts the wheel slip ratio only as needed during the wheel slip ratio process, i.e., only when the fourth slip ratio extreme value is exceeded, by adjusting the hydraulic brake through slip adjustment.

[0014] Particularly preferably, once the actual slip ratio value falls below the corresponding slip ratio extreme value, the operation to maintain the third and / or fourth slip ratio extreme values ​​is terminated. By correspondingly terminating the operation to maintain the corresponding extreme value, the method can be executed with particular efficiency. This is especially stepwise; once the slip ratio falls below the fourth slip ratio extreme value again, slip adjustment using the second actuator assembly is stopped, and the wheel slip ratio continues to be adjusted using the first actuator assembly, for example, by the aforementioned pre-set motor speed. If the slip ratio also falls below the third slip ratio extreme value during the slip adjustment process, that adjustment is also terminated.

[0015] The computer program product according to the invention, which has the features of claim 10 and is intended to be executed on a computing device, is characterized in that it executes the method according to the invention when used as intended. This provides the aforementioned advantages.

[0016] The machine-readable storage medium according to the invention, having the features of claim 11, is characterized by a computer program product according to the invention stored thereon.

[0017] The computing device having the features of claim 12 is characterized in that it is specifically designed for implementing the computer program product according to the invention or performing the method according to the invention. This also yields the aforementioned advantages. Preferably, the computing device is a control device and / or control unit associated with a motor vehicle, particularly arranged in a motor vehicle. Attached Figure Description

[0018] Further preferred features and combinations thereof are derived from the preceding description and the claims. The invention is described in detail below with reference to the accompanying drawings. For this purpose, it is shown that:

[0019] Figure 1 A preferred method for operating motor vehicles.

[0020] Figure 2 : A first example of the torque and slip ratio trends during the execution of this method.

[0021] Figure 3 : A second example of the trends in torque and slip ratio, and

[0022] Figure 4 The third example of the trend of torque and slip ratio. Detailed Implementation

[0023] Figure 1 The block diagram, combined with the mechanism of the wheel assembly actuator for controlling the motor vehicle 1 via lateral dynamic stabilization, illustrates a preferred method for operating the motor vehicle 1. The components involved are shown schematically only.

[0024] The motor vehicle 1 includes at least one axle 2 having at least one wheel 3. Furthermore, the motor vehicle 1 includes an electric drive device 4 having a controllable first actuator assembly 5. The first actuator assembly 5 has a motor 6.

[0025] The motor vehicle 1 also has a hydraulic wheel braking device 7, which has a controllable second actuator assembly 8 (not shown in detail). The second actuator assembly 8 includes, in particular, a hydraulic pump, an electric motor and / or a hydraulic valve assembly associated with the hydraulic pump. The two actuator assemblies 5 and 8 are respectively associated with the wheels 3 and are therefore part of the wheel assembly actuator 9 already mentioned.

[0026] Finally, the motor vehicle 1 also has at least one computing device 10 configured to at least partially, and especially fully, execute the methods further described, such as the coordinated manipulation of actuator assemblies 5, 8. Preferably, the computing device 10 has at least one, and especially all, modules described below and / or is configured to implement at least one of the functions mentioned below or to perform corresponding method steps involving the already mentioned lateral dynamic stability functions. The computing device 10 is particularly configured as an electronic control device and / or a control unit (ECU).

[0027] As already mentioned, in Figure 1 The diagram illustrates the mechanism for manipulating the wheel assembly actuator 9 via a lateral dynamic stabilization function. To this end, various functions or modules (software and / or hardware), their connections to the actual wheel assembly actuator 9 in terms of their respective input and output parameters, are drawn to illustrate the method according to the invention.

[0028] The lateral dynamic stability function of motor vehicle 1 currently includes yaw rate adjustment, also known as Vehicle Dynamics Control (VDC), which constitutes the first module 11; trailer stabilization, also known as Trailer Sway Mitigation (TSM), which constitutes the second module 12; and rollover prevention, also known as Roll Over Mitigation (ROM) or Roll Movement Intervention (RMI), which constitutes the third module 13.

[0029] What all functions or modules 11-13 have in common is that they utilize the provided sensor signals to measure vehicle motion (yaw rate). Longitudinal acceleration a x lateral acceleration a y and vehicle speed v x ) and the driver's steering expectations (front axle steering angle δ) FA ( ) as their respective input signals. For the control of the wheel assembly actuator 9, it is important to know the motor 6 of the first actuator assembly 5, i.e., the drive motor, up to which limit should it be used.

[0030] Therefore, the yaw moment potential of the actuator is determined. The yaw moment potential is determined by a physical wheel model (e.g., the Pacejka wheel model known from the literature) and a dual-track model for motor vehicle 1, constituting a common fourth module 14. The wheel model obtains the slip limit. This is used as an input parameter. This input parameter characterizes the slip limit of wheel 3 when it is braked by motor 6.

[0031] The torque limit obtained from the wheel model as the output parameter. The dual-trajectory model is used as an input parameter in Module 15, where it is converted into the first and second yaw moment limits about the vertical axis. and Here, the first yaw moment limit... The maximum possible yaw moment in the clockwise direction (pos), the second yaw moment limit The maximum possible yaw moment is called the counterclockwise direction (neg).

[0032] These yaw moment limits and The first yaw moment ratio, which is the output parameter of the fifth module 15, and the output parameter of the first module 11. And the second yaw moment share as an output parameter of the second module 12 Together they enter into the yaw moment distribution, forming the sixth module 16.

[0033] In the yaw moment distribution, the yaw moment share will be... and As an input parameter or requirement, it relates to the yaw torque limit of motor 6. and Compare them.

[0034] If the requirement is to be less than the yaw moment limit or This translates into a temporary first braking torque share for the motor 6 of the first actuator assembly 5. However, if one of the yaw moment limits is exceeded... or Then, the temporary second braking torque share for the second actuator assembly 8 of the hydraulic brake is additionally calculated. .

[0035] The execution arbitration constituting the seventh module 17 incorporates the braking torque shares for all lateral dynamic stabilization functions of the wheel assembly actuator 9. Here, in addition to the temporary first braking torque share, which is an output parameter of the sixth module 16, [this is also included]. and temporary second braking torque share In addition, it will also serve as the third braking torque share of the output parameter of the third module 13. Used as their respective input parameters.

[0036] In modules 16 and 17, the total braking torque on wheel 3 is determined in the first step based on the braking request. How high. In another step, determine which actual or final braking torque share. The motor 6 enters the first actuator assembly 5, and which final braking torque share... The second actuator assembly 8 enters the hydraulic brake. Currently, this is achieved by obtaining the torque limit from the wheel model as an output parameter. 'a' occurs as another input parameter in module 17. The sum of the two braking torque components corresponds to the braking torque on wheel 3. .

[0037] The structure chosen here, particularly the functional division between modules 16 and 17, is generated by a functional architecture aimed at separating the requirements at the vehicle level (yaw moment) and the wheel level (wheel moment). This allows for the advantageous coordination of driving dynamic stability functions at the correct locations.

[0038] The sliding adjustment used for the lower layer of the second actuator assembly 8 constitutes the eighth module 18, in addition to the final second braking torque share. In addition, the slip limit is obtained from module 17 as an input parameter. and the wheel speed from wheel 3 To adjust hydraulic pressure ; and for the speed regulation of the lower layer of the motor 6 used in the first actuator assembly 5, forming the ninth module 19, in addition to the final first braking torque share In addition, the speed limit is obtained from module 17 as an input parameter. The speed limit is determined by the slip limit. The result is the wheel speed from wheel 3. To adjust the braking torque share The two lower-level regulators are responsible for maintaining the required limits.

[0039] The core of the method according to the invention is located in modules 17 to 19, which will be described below. Here, each actuator assembly 5, 8 is respectively assigned at least one, particularly wheel-specific, slip ratio extreme value; currently, at least the first actuator assembly 5 is assigned a slip limit. As the extreme value of the slip ratio, the second actuator assembly 8 is equipped with a slip limit. As another extreme value of slip ratio. Slip limit. It is also considered as another slip ratio extreme value. In addition, actuator assemblies 5 and 8 are manipulated according to their respective pre-given slip ratio extreme values ​​to meet braking requests.

[0040] Now, based on three examples, we will illustrate how, within the scope of the method, braking torque distribution can be achieved using the execution arbitration in module 17, and how corresponding adjustments can be made using slip adjustment and speed adjustment in modules 18 and 19.

[0041] Here, at least four distinct slip ratio extrema are used, including the three slip ratio extrema already mentioned. For simplicity, these slip ratio extrema are numbered in ascending order of their values ​​below, whereby the numbering is used only for their distinction, not for their priority or pre-given, and does not imply any necessary correlation between the extrema.

[0042] Preferably, at least one slip ratio extreme value is pre-given based on the performance of the corresponding actuator components 5, 8 and / or the driving mode of the vehicle 1, particularly including comfort mode and / or sport mode.

[0043] Here, Figures 2 to 4 The torque and slip ratio trends during the execution of the method under different driving conditions are shown separately. Here, in Figures 2 to 4 The upper half shows the trend curve of torque M over time t, and the lower half shows the trend curve of wheel slip ratio λ over time t.

[0044] Figure 2The first example is shown, illustrating the trend of braking torque distribution over time with a stable wheel slip ratio trend. Figure 3 The second example is shown, which illustrates the trend of braking torque distribution over time with unstable wheel slip ratio and active (electric) speed regulation. Figure 4 The third example is shown, which features an unstable wheel slip ratio trend and the trend of braking torque distribution over time with active (hydraulic) slip regulation and (electric) speed regulation.

[0045] The time points described below are numbered such that at the same time points, at least approximately the same event occurs, so that the examples shown can be better compared.

[0046] First, the vehicle is monitored for braking requests. The actual value of the wheel slip ratio λ is calculated accordingly, and once the corresponding braking request is identified, the first actuator assembly 5 is controlled, especially by means of the speed regulation of motor 6, according to the actual value of the slip ratio, to generate electric braking torque.

[0047] Therefore, the motor 6 of the first actuator assembly 5 is actuated starting at time point t0. This will increase the first braking torque share. It is applied to motor 6. Then, the wheel slip ratio also increases. First braking torque share This corresponds to the electric braking torque.

[0048] A first slip ratio extreme value is now pre-defined and assigned to the second actuator assembly 8. When the actual slip ratio value reaches at least, and especially exceeds, the first slip ratio extreme value, the second actuator assembly 8, especially the motor assigned to the hydraulic pump, is operated in addition to pre-filling the hydraulic circuit of the wheel braking device 7.

[0049] exist Figure 2 As can be seen, from reaching the slip limit Starting from time point t1, an additional, constant braking torque is pre-applied to the hydraulic wheel braking device 7. Furthermore, it is hydraulically pre-filled until time point t2. This avoids the potential weakness of the hydraulic wheel braking device 7 in building up pressure. Slip limit This corresponds to the first extreme value of the slip ratio.

[0050] The slip limit is chosen so high that it allows for a more reliable fit to the brake pads. For example, the slip limit is determined based on hydraulic pressure values, particularly in the range of up to 10 bar, such as 5 bar, and / or the cp characteristic value of the friction brake.

[0051] A second slip ratio extreme value is further predetermined and assigned to the second actuator assembly 8. When the actual slip ratio value reaches at least, and especially exceeds, the second slip ratio extreme value, the second actuator assembly 8 is actuated to generate additional hydraulic braking torque.

[0052] Until time point t2, otherwise only electric control is performed, i.e., using the first actuator assembly 5, specifically until the slip limit already used in the wheel model. Therefore, slip limit This corresponds to the second slip ratio extremum. Therefore, the second slip ratio extremum is greater than the first slip ratio extremum.

[0053] Motor control is specifically achieved through a target torque derived from the slip limit. This slip limit results in a maximum torque. If the entire braking request falls within this range, this maximum torque is provided as the target torque.

[0054] The slip limit is reached or exceeded at time t2. Now, another increased second braking torque share is applied via the second actuator assembly 8. It is applied to the hydraulic wheel braking device 7 and thus hydraulically controlled. Second braking torque share. This corresponds to the additional hydraulic braking torque.

[0055] A third slip ratio extreme value is further predetermined and assigned to the first actuator assembly 5. When the actual slip ratio value reaches at least, and especially exceeds, the third slip ratio extreme value, the first actuator assembly 5 is manipulated to maintain the third slip ratio extreme value, and especially to reduce the actual slip ratio value to the third slip ratio extreme value.

[0056] exist Figure 2 As can be seen, the second actuator assembly 8 is manipulated until the slip limit is reached. The slip limit is reached at time t3. Since this slip limit is not exceeded, no adjustment is made via the first actuator assembly 5. Slip Limit This corresponds to the third slip ratio extreme. Therefore, the third slip ratio extreme is greater than the first and second slip ratio extremes.

[0057] In the described example, the total braking request exceeds the maximum torque for motor 6, such that the remaining torque share is pre-given as the target torque for wheel braking device 7. The target slip ratio for motor 6 is achieved through the slip limit. It is limited to a defined slip ratio range. The target slip ratio for wheel braking device 8 is determined by the slip limit. Limited increase to slip limit And so it was concluded.

[0058] Pre-setting target slip ratios for the respective actuator assemblies 5 and 8 is primarily for ensuring the pre-set torque. The control signal for the respective actuator assemblies 5 and 8 is always torque. The lower-level wheel adjuster is activated and limits the wheel slip ratio to the pre-set target slip ratio only when the wheel slip ratio is higher than the pre-set target slip ratio for the respective actuator assemblies 5 and 8. This will... Figure 3 and Figure 4 It is described in detail in the text.

[0059] Furthermore, based on the third slip ratio extreme value, a speed extreme value is pre-given to the motor 6 of the first actuator assembly 5, and when the third slip ratio extreme value is reached or exceeded, the motor 6 is controlled by speed regulation based on the speed extreme value.

[0060] Here, by the slip limit The speed limit for motor 6, as already mentioned, has been obtained. Speed ​​limits This corresponds to the extreme speed of motor 6.

[0061] Finally, a fourth slip ratio extreme value is pre-defined and assigned to the second actuator assembly 8. When the actual slip ratio value reaches at least, and especially exceeds, the fourth slip ratio extreme value, the second actuator assembly 8, especially the hydraulic valve assembly, is actuated to maintain the fourth slip ratio extreme value, and especially to reduce the actual slip ratio value to the fourth slip ratio extreme value.

[0062] Currently, for this purpose, the slip limit, which has already been mentioned, is additionally pre-defined. The slip limit is always higher than the slip limit. And preferably relative to the slip limit The limited offset is implemented. Slip limit. This corresponds to the fourth slip ratio extreme. Therefore, the fourth slip ratio extreme is greater than the first, second, and third slip ratio extremes. Currently, two slip limits are maintained. and This eliminates the need for corresponding adjustments.

[0063] exist Figure 2 In the middle, slip limit As shown in the enlarged view next to the wheel slip ratio trend, it lies within the linear or stable region of the slip ratio curve of wheel 3. The slip ratio and the torque remain constant until time point t6, and then decrease.

[0064] from Figure 2 It can be seen that in the total braking torque From time point t6 onwards, as the decay begins, the braking torque distribution proceeds in reverse order. First, the second braking torque share... The braking force decreases at time point t7 until the constant braking torque used for pre-filling is reached. .

[0065] Subsequently, reduce the share of the first braking torque. From the previously described slip limit, we can deduce when and for how long each braking torque component begins to decrease. Therefore, the slip limit is reached again at time t8. And cancel the additional braking torque. At time t9, the braking request is finally fully satisfied and the first braking torque share is reached. Reduce to zero.

[0066] exist Figure 2 The braking torque distribution shown indicates that the lateral dynamic stability function can be required earlier and unnoticed by the driver through this sequence, since the motor 6 of the drive unit 4 is used first. The wheel braking device 7 is also optimally incorporated in such a way that the pressure build-up dynamics are improved through pre-filling, and the perceptible NVH characteristics of the brake hydraulic system only appear at a later point in time.

[0067] exist Figure 3 The braking torque distribution described earlier can also be seen here. Similarly, electrical control is performed from time point t0 to time point t2, hydraulic pre-filling is performed from time point t1 to time point t2, and hydraulic control is performed from time point t2 onwards.

[0068] Because of slip limit Currently, the slip ratio is below the critical or minimum slip ratio value within the unstable region of the slip ratio curve. Therefore, an unstable wheel slip ratio trend is observed in the hydraulically controlled region. Consequently, at time point t3, the slip limit during hydraulic control is exceeded. Next, the motor 6 was adjusted to its speed limit. This phase is necessary to maintain the slip limit. .

[0069] Therefore, the situation described above occurs, where the actual slip ratio exceeds the third slip ratio extreme value. Accordingly, the first actuator assembly 5 is manipulated to maintain the third slip ratio extreme value, and more particularly to reduce the actual slip ratio value to the third slip ratio extreme value, currently controlled by speed regulation based on the speed extreme value.

[0070] At time point t5, the slip limit is maintained at least approximately. Or, to put it another way, the wheel slip ratio only slightly hovered around the slip limit up to time t6. Fluctuation. Slip limit It was maintained or not exceeded. Therefore, the speed regulation was successful, where only the first braking torque share was modulated between time points t5 and t6. The second braking torque share Keep it constant.

[0071] Therefore, once the actual slip ratio value is lower than the slip ratio extreme value, the manipulation used to maintain the third slip ratio extreme value ends.

[0072] and Figure 2 Similarly, starting from time point t6, the second braking torque share will be... Until time point t7 decreases to a constant braking torque Then reduce the first braking torque share. The additional braking torque is canceled at time point t8. At time t9, the first braking torque share will be... Reduce to zero.

[0073] exist Figure 4 The braking torque distribution described earlier is seen again. Electrical control is performed from time point t0 to time point t2, hydraulic pre-filling is performed from time point t1 to time point t2, and hydraulic control is performed from time point t2 onwards.

[0074] Because of slip limit Again, it falls below the minimum slip ratio value within the unstable region of the slip ratio curve. Therefore, an unstable wheel slip ratio trend is observed in the hydraulically controlled region. Consequently, at time point t3, the slip limit during hydraulic control is exceeded. Next, the motor 6 was adjusted to its speed limit. This phase is necessary to maintain the slip limit. .

[0075] Therefore, the situation described above occurs, where the actual slip ratio exceeds the third slip ratio extreme value. Accordingly, the first actuator assembly 5 is manipulated to maintain the third slip ratio extreme value, and more particularly to reduce the actual slip ratio value to the third slip ratio extreme value, currently controlled by speed regulation based on the speed extreme value.

[0076] However, the instability was so severe that the slip limit was exceeded at time t4 during hydraulic control. Now comes a brief phase until time point t5, during which hydraulic adjustments are made until the wheel slip ratio falls below the slip limit again. In parallel with this, an electrical regulation phase occurs in order to also maintain the slip limit. In this regard, between time points t4 and t5, not only is the first braking torque portion modulated... Moreover, modulate the second braking torque share .

[0077] Therefore, the situation described above occurs, where the actual slip ratio exceeds the fourth slip ratio extreme value. Accordingly, the second actuator assembly 8, particularly the hydraulic valve assembly, is additionally manipulated to maintain the fourth slip ratio extreme value, and particularly to reduce the actual slip ratio value to the fourth slip ratio extreme value.

[0078] After time point t5, the slip limit is maintained at least approximately again. Or, to put it another way, the wheel slip ratio only slightly hovered around the slip limit up to time t6. Fluctuations. Slip regulation and speed regulation using the combination of two actuator assemblies 5 and 8 were successful. Modulation of only the first braking torque fraction was performed again between time points t5 and t6. While maintaining the share of the second braking torque Constant.

[0079] Once the actual slip ratio value falls below the corresponding slip ratio extreme value, the manipulation used to maintain the third and fourth slip ratio extreme values ​​ends.

[0080] and Figure 2 and Figure 3 Similarly, starting from time point t6, the second braking torque share will be... Until time point t7 decreases to a constant braking torque Then reduce the first braking torque share. The additional braking torque is canceled at time point t8. And at time t9, the first braking torque share will be... Reduce to zero.

[0081] Therefore, in Figure 3 and Figure 4 The example illustrated demonstrates the wheel slip ratio adjustment strategy according to the invention via wheel combination actuator 9, which operates precisely when the wheel slip ratio enters an unstable region or, for example, when a corresponding wheel slip ratio is intentionally allowed in a motion mode; otherwise, as... Figure 2 As shown, the slip ratio should not exceed the extreme values ​​associated with the corresponding adjustment. By selecting the slip limit, the wheel slip ratio is ensured to be primarily adjusted by motor 6. This advantageously utilizes its high dynamics and rapid adjustability.

Claims

1. A method for operating a motor vehicle (1), - The motor vehicle (1) therein has at least one axle (2), and the at least one axle has at least one wheel (3). - The wheel (3) is equipped with an electric drive device (4) having a controllable first actuator assembly (5), the first actuator assembly including a motor (6), and - The wheel (3) is equipped with a wheel braking device (7) having a controllable second actuator assembly (8). Its features are, - Each actuator assembly (5, 8) is equipped with at least one, especially the wheel-specific slip ratio extreme value (λ). Hyd,Vor , λ Elec,min , λ Rad,lim , λ Hyd ),and - Based on the pre-given extreme value of the slip ratio (λ) Hyd,Vor , λ Elec,min , λ Rad,lim , λ Hyd The actuator assembly (5, 8) is operated to meet the braking request.

2. The method according to the preceding claims, wherein the wheel braking device has another motor and / or the wheel braking device is a hydraulic wheel braking device and has a motor and / or hydraulic valve assembly associated with a hydraulic pump.

3. The method according to any one of the preceding claims, characterized in that, The extreme value of the slip ratio (λ) Hyd,Vor , λ Elec,min , λ Rad,lim , λ Hyd At least one slip ratio extreme value in the motor vehicle (1) is pre-given based on the performance of the corresponding actuator components (5, 8) and / or the driving mode of the motor vehicle (1), the driving mode including in particular comfort mode and / or sport mode.

4. The method according to any one of the preceding claims, characterized in that, The actual slip ratio (λ) of the wheel is obtained, and initially only the first actuator assembly (5) is controlled according to the actual slip ratio, particularly by means of the speed regulation of the motor (6), to generate the electric braking torque (M). Elec ).

5. The method according to claim 4, characterized in that, Pre-defined first slip ratio extreme value (λ) Hyd,Vor ) and assigned to the second actuator assembly (8), wherein when the actual value of the slip ratio reaches at least, in particular exceeds, the first slip ratio extreme value (λ) Hyd,Vor When the second actuator assembly (8) is operated, in particular the motor assigned to the hydraulic pump, is operated to prefill the hydraulic circuit of the wheel braking device (7).

6. The method according to any one of claims 4 and 5, characterized in that, Pre-defined second slip ratio extreme value (λ) Elec,min ) and assigned to the second actuator assembly (8), wherein the second slip ratio extreme (λ) Elec,min Especially greater than the first slip ratio extreme value (λ) Hyd,Vor ), and when the actual value of the slip ratio reaches at least, and in particular exceeds, the second slip ratio extreme value (λ) Elec,min When the second actuator assembly (8) is operated, it is used to generate additional, especially hydraulic, braking torque (M). Hyd ).

7. The method according to any one of claims 4 to 6, characterized in that, Pre-defined third slip ratio extreme value ((λ) Rad,lim ), especially in the unstable region of the wheel slip ratio curve and assigned to the first actuator assembly (5), wherein the third slip ratio extreme (λ) Rad,lim Especially those greater than the first slip ratio extreme value (λ) Hyd,Vor ) and / or the second slip ratio extreme value (λ) Elec,min ), and when the actual value of the slip ratio reaches at least, and in particular exceeds, the third slip ratio extreme value (λ) Rad,lim When ), the first actuator assembly (5) is manipulated to maintain the third slip ratio extreme value (λ). Rad,lim In particular, it is used to reduce the actual value of the slip ratio to the third slip ratio extreme value (λ). Rad,lim ).

8. The method according to claim 7, characterized in that, According to the third slip ratio extreme value (λ) Rad,lim The motor (6) of the first actuator assembly (5) is given a pre-defined extreme speed (ω). Elec ), and according to the extreme value of the rotational speed (ω) Elec The motor (6) is controlled by means of speed regulation.

9. The method according to any one of claims 4 to 8, characterized in that, Pre-defined fourth slip ratio extreme value (λ) Hyd ) and assigned to the second actuator assembly (8), wherein the fourth slip ratio extreme (λ) Hyd Especially greater than the first slip ratio extreme value (λ) Hyd,Vor ), the second slip ratio extreme value (λ) Elec,min ) and / or the third slip ratio extreme (λ) Rad,lim ), and when the actual value of the slip ratio reaches at least, and in particular exceeds, the fourth slip ratio extreme value (λ) Hyd When operating the second actuator assembly (8), especially the hydraulic valve assembly, to maintain the fourth slip ratio extreme value, and especially to reduce the actual slip ratio value to the fourth slip ratio extreme value (λ). Hyd ).

10. The method according to any one of claims 7 to 9, characterized in that, Once the actual value of the slip ratio is lower than the corresponding slip ratio extreme value (λ) Rad,lim , λ Hyd Then the process of maintaining the third slip ratio extreme value (λ) ends. Rad,lim ) and / or the fourth slip ratio extreme (λ) Hyd (Control) 11. A computer program product for execution on a computing device (10), characterized in that, When used as specified, the computer program product performs the method according to any one of the preceding claims.

12. A machine-readable storage medium having a computer program product according to claim 11.

13. A computing device (10), particularly an electronic control device and / or control device, for a motor vehicle (1), characterized in that, The computing device (10) is specifically designed to execute the computer program product according to claim 11.

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