Methods for operating automobiles, computer program products, storage media, computer devices

Abstract

To improve the brake control of an automobile. 【Solution means】 A method of operating an automobile (1), the automobile (1) having at least one axle (2) with at least one wheel (3), the wheel (3) being attached with an electric drive device (4) having a controllable first actuator mechanism (5) with an electromechanical machine (6), and a hydraulic wheel brake device (7) having a controllable second actuator mechanism (8) with an electromechanical machine and / or a hydraulic valve mechanism attached to the wheel (3), the first and second actuator mechanisms (5, 8) each having at least one slip limit value (λ Hyd,Vor , λ Elec,min , λ Hyd , λ Rad,lim ) assigned thereto, and being controlled depending on a set slip limit value (λ Hyd,Vor , λ Elec,min , λ Hyd , λ Rad,lim ) to meet the braking requirement.

Description

[Technical Field]

[0001] The present invention relates to a method for operating an automobile, wherein the automobile has at least one axle having at least one wheel, the wheel is fitted with an electrically operated drive unit having a controllable first actuator mechanism having an electromechanical element, and the wheel is fitted with a hydraulic wheel brake unit having a controllable second actuator mechanism having an electromechanical and / or hydraulic valve mechanism, in particular fitted with a hydraulic pump.

[0002] Furthermore, the present invention relates to a computer program product that performs the above method when the computer program product is executed on a computer device. Furthermore, the present invention relates to a machine-readable storage medium having such a type of computer program product, and in particular to a computer device set up for executing the computer program product or for performing the above method. [Background technology]

[0003] Automobiles with hydraulic wheel brake systems and vehicle dynamic control systems are known from prior art. Modern vehicle dynamic control systems typically include a vehicle dynamic control unit and a brake hydraulic system. The brake hydraulic system is connected to the wheel brake cylinders of the wheel brake system via brake piping. Brake pressure in the wheel brake cylinders can be adjusted via various valves and hydraulic pumps.

[0004] For example, such a vehicle dynamic control system is known from the applicant's Patent Document 1. The document describes how the vehicle dynamic controller interacts with the brake fluid system. The vehicle dynamic controller basically consists of a yawing speed controller. The yawing speed controller receives a yawing speed signal, a wheel speed signal to form the vehicle speed, a steering angle signal, and a lateral acceleration signal from the measurement data detection unit. The yawing speed controller uses the measurement signals and a physical model of the vehicle's yawing motion to form a target yawing speed. Depending on the driving conditions, the yawing speed controller triggers hydraulic brake intervention to stabilize the vehicle. To this end, the current target wheel slip is raised or lowered by a lower-level wheel controller, or the target wheel brake pressure is changed by the output of the valve opening time of the brake fluid system.

[0005] Continuous improvements to vehicle dynamic control systems have led to the development of functions beyond yawing speed controllers. These include rollover mitigation (ROM) or roll movement intervention (RMI), as well as trailer stabilization, also known as trailer sway mitigation (TSM). All of these functions are now included in the lateral dynamics stabilization capabilities of vehicle dynamic control systems, and what they all have in common is the use of the brake fluid system to generate hydraulic brake intervention to stabilize the vehicle. Furthermore, the increasing electrification of vehicles has led to drive concepts with individual electric motors for each wheel. These can generate not only drive torque but also brake torque. And if both of these regulators—hydraulic wheel brakes and electric drive motors—are integrated into the vehicle's wheels, both can be utilized by the lateral dynamics stabilization function to generate brake intervention when stabilizing the vehicle. [Prior art documents] [Patent Documents]

[0006] [Patent Document 1] German Patent Application Publication No. 4305155 Specification [Overview of the project]

[0007] The method of the present invention having the constituent elements of claim 1 is characterized in that each actuator mechanism is assigned at least one, particularly wheel-specific, slip limit value, and the actuator mechanism is controlled depending on the set slip limit value in order to satisfy a brake request. As described at the beginning, vehicle dynamic control systems typically utilize hydraulic wheel brakes to stabilize the vehicle. Alternatively, other braking modes are possible, such as electromechanical brakes. If the vehicle has further regulators for each wheel, as intended under the present invention, in this case electric drive motors, the stabilization problem can be solved by the best control of a wheel-composite regulator including the wheel brakes and drive motors that results. This has the advantage that both actuator mechanisms are best incorporated into and utilized by vehicle dynamic control within the framework of slip control when satisfying a brake request. Brake requests are detected and / or determined, in particular, by a sensor mechanism and set and / or received by an operating device and / or control device. To that extent, the present invention provides a control strategy in which both actuator mechanisms are jointly controlled to best generate brake torque on the corresponding wheels. Of particular importance here is the division of brake torque into hydraulic and electric brake torque, as well as the necessary wheel slip monitoring. With respect to wheel slip monitoring, the present invention presents the possibility of solving this problem, in particular through the hydraulic brake by a lower-level wheel controller and through the electric drive motor by a rotational speed controller. For this purpose, slip limit values ​​intended under the present invention are utilized. Just to be clear, the numbering of the slip limit values ​​used below is merely for distinguishing them and does not imply any priority or specification, nor does it imply any necessary interdependence between the respective limit values.According to the present invention, only two different slip limit values ​​are required, one of which is assigned to at least a first actuator mechanism and the other to at least a second actuator mechanism, thereby ensuring that it is determined when and how each of the two actuator mechanisms is controlled and utilized within the framework of the method according to the present invention. For example, the limit values ​​described below as third and fourth slip limit values ​​are used as minimum conditions. This leads to the prioritization of the first actuator mechanism, thereby preferably the brake torque is regulated and controlled by the first actuator mechanism as preferentially as possible, and especially exclusively. The resulting brake torque distribution sequence, also described in detail below as an example, has advantages in terms of comfort and timing of vehicle stabilization. Control of the electric drive motor can be initiated early during vehicle stabilization, in the region of vehicle motion that is still outside the region of lateral dynamics (yaw rate control) and the tilt critical region (rollover prevention). These regions cannot be considered from a hydraulic perspective from the standpoint of driving comfort. This is because when hydraulic brakes are controlled, noise is inevitably generated by the hydraulic pumps and valve switching within the brake fluid system. The fact that the driver can always perceive the lateral dynamics stability function in the less critical areas of vehicle motion clearly reduces driving comfort. Yet another advantage of the preferred use of the first actuator mechanism is the improved control quality when wheel slip is adjusted. For example, high cycle times in milliseconds, especially 1 ms, for electromechanical rotational speed control enable improved wheel slip control in the unstable slip region of the wheel. This benefits not only yaw rate control but also rollover prevention, which is clearly encountered much more frequently when the vehicle is in strong body motion. In such cases, strong wheel load fluctuations occur, which in turn strongly affect the wheel slip behavior.In summary, the present invention's approach to slip-value-dependent wheel composite regulator control offers advantages such as improved comfort and timing of vehicle stabilization, particularly the optimal distribution of brake torque ratios to the hydraulic brakes and electric drive motors, as well as improved wheel slip control related to control quality, as this is prioritized through the rotational speed control of the electric drive motors. The use of corresponding actuator-specific slip limits, as intended under this invention, is a particularly preferred, simple, and sophisticated solution for robustly realizing such prioritization.

[0008] In a preferred evolution of the present invention, at least one of the slip limit values ​​is set depending on the capability of each actuator mechanism and / or in particular on the driving mode of the vehicle, including comfort mode and / or sport mode. Such capability-dependent and / or mode-dependent setting of each slip limit value preferably ensures that each slip limit value is best adapted to the health of each actuator mechanism and / or to the driving behavior desired by each driver. For example, a corresponding slip limit value is selected so that when the capability of one of the actuator mechanisms decreases, the other actuator mechanisms each bear a higher proportion of the brake torque that should be adjusted to meet the braking requirement. Similarly, in sport mode, for example, a higher slip limit value is set, or higher wheel slip is permitted, before corresponding active slip control is performed, for example, in comfort mode. In particular, at least one of the slip limit values ​​is defined with a safety margin set within a specific range, and / or within a range, up to, for example, 50%, 75%, or 90% of the maximum capability, in order to avoid placing an excessive load on the actuator mechanism.

[0009] The actual slip value of the wheel slip is determined, and it is particularly preferable that only the first actuator mechanism is controlled, especially by electromechanical rotational speed control, to generate electric brake torque depending on the actual slip value. This type of control has the advantage of prioritizing the use of the first actuator mechanism. In particular, an attempt is made first to provide the brake torque to be adjusted to meet the braking requirement by the first actuator mechanism alone, especially by electromechanical operation, generator operation, or regenerative operation. The second actuator mechanism is then added and turned on only as needed.

[0010] In a preferred development of the present invention, a first slip limit is set and assigned to a second actuator mechanism, and when the actual slip value reaches at least the first slip limit, and particularly exceeds it, the second actuator mechanism, in particular an electromechanical unit attached to a hydraulic pump, is additionally controlled to pre-fill the hydraulic circuit of the wheel brake system. By setting and utilizing the first slip limit appropriately, it is preferably ensured that the second actuator mechanism is ready to generate brake torque earlier, for example, if the actual slip value increases further. To that extent, there is an advantage in that the reaction time for controlling the second actuator mechanism is further reduced. However, this is not essential for the method according to the present invention.

[0011] A second slip limit is set and assigned to a second actuator mechanism, and it is particularly preferable that the second slip limit be greater than the first slip limit, and that the second actuator mechanism be controlled to generate additional hydraulic brake torque when the actual slip value reaches at least the second slip limit, and especially when it exceeds it. The appropriate setting and use of the second slip limit provides the advantage that, under the slip conditions defined by the limit, the second actuator mechanism is reliably turned on to assist the first actuator mechanism in meeting the brake requirements. The second slip limit is determined, for example, depending on the capabilities of the first actuator mechanism, so as to ensure that the first actuator mechanism is not overloaded by the timely activation of the second actuator mechanism. To that extent, the slip limit determines what percentage of the brake torque is provided by the first actuator mechanism or its electromechanical unit. The slip limit also defines an upper limit on the brake torque. Only brake torque ratios exceeding this limit are provided by the second actuator mechanism and the associated hydraulic wheel brake system.

[0012] In a preferred evolution of the present invention, a third slip limit is set and assigned to the first actuator mechanism, particularly in an unstable region of the wheel slip curve, and the third slip limit is particularly greater than the first and / or second slip limits, and when the actual slip value reaches at least the third slip limit, particularly when it exceeds it, the first actuator mechanism is controlled to comply with the third slip limit, particularly to reduce the actual slip value to the third slip limit. By setting and utilizing the third slip limit appropriately, it is preferably ensured that the wheel slip is controlled by the first actuator mechanism. If the brake torque ratio provided by both actuator mechanisms leads to a correspondingly high wheel slip, the first actuator mechanism attempts to maintain the wheel at a desired wheel slip when it exceeds a corresponding third slip limit, particularly by setting the rotational speed to the electromechanical unit. In particular, this desired wheel slip, characterized by the third slip limit, corresponds to the best wheel slip to satisfy the braking requirement.

[0013] It is particularly preferable that a rotational speed limit is set for the electromechanism of the first actuator mechanism depending on a third slip limit, and that the electromechanism is controlled by rotational speed control depending on the rotational speed limit. This type of rotational speed control offers the advantage of particularly precise control of wheel slip.

[0014] In a preferred development of the present invention, a fourth slip limit is set and assigned to a second actuator mechanism, the fourth slip limit being particularly greater than the first, second, and / or third slip limits, and when the actual slip value reaches at least the fourth slip limit, particularly when it exceeds it, the second actuator mechanism, particularly the hydraulic valve mechanism, is controlled to comply with the fourth slip limit, particularly to reduce the actual slip value to the fourth slip limit. The advantage of setting and utilizing a fourth slip limit is that if the first actuator mechanism cannot maintain wheel slip near the slip limit assigned to it, the second actuator mechanism is guaranteed to perform auxiliary control to always ensure driving safety. To that extent, the second actuator mechanism performs wheel slip control only as needed in the subsequent process of wheel slip control, i.e., only when it exceeds the fourth slip limit. Only then is the hydraulic brake controlled through slip control.

[0015] The control for adhering to the third and / or fourth slip limits is particularly preferably terminated as soon as the actual slip value falls below the respective slip limit. The appropriate termination of the control for adhering to each of the one or more limits provides the advantage that the method is implemented particularly efficiently. This is done in a stepwise manner, namely, as soon as the fourth slip limit is again fallen below, the slip control by the second actuator mechanism is stopped, and the wheel slip is subsequently controlled by the first actuator mechanism, for example, through setting the rotational speed to the electromechanical device as described above. If the third slip limit is also fallen below during the subsequent process of slip control, this control is also terminated.

[0016] A computer program product according to the present invention, having the constituent elements of claim 10 and for execution on a computer device, is characterized by implementing the method according to the present invention when used in a manner appropriate to the application. This brings about the advantages already mentioned.

[0017] A machine-readable storage medium according to the present invention having the constituent elements of claim 11 is characterized by having a computer program product according to the present invention stored therein.

[0018] A computer device having the constituent elements of claim 12 is characterized in that the computer device is specially set up for executing a computer program product according to the present invention or for carrying out a method according to the present invention. This also brings about the advantages already mentioned above. The computer device is preferably a control device and / or control device attached to, or particularly located in, an automobile.

[0019] Other preferred constituent elements and combinations of constituent elements will become apparent from the above description and the claims. The present invention will now be described in detail with reference to the drawings. [Brief explanation of the drawing]

[0020] [Figure 1] This is a preferred method for operating an automobile. [Figure 2] This is the first example of the changes in torque and slip during the implementation of this method. [Figure 3] This is a second example of the transitions between torque and slip. [Figure 4] This is a third example of the transition between torque and slip. [Modes for carrying out the invention]

[0021] Figure 1 shows a preferred method of operating automobile 1, which has a mechanism for controlling the wheel composite regulator of automobile 1 by a lateral dynamics stabilization function, using a block diagram. The components involved are shown schematically only.

[0022] Here, the automobile 1 has at least one axle 2 having at least one wheel 3. Furthermore, the automobile 1 has an electric drive unit 4 having a controllable first actuator mechanism 5. The first actuator mechanism 5 has an electromechanism 6.

[0023] Automobile 1 further has a hydraulic wheel brake system 7 having a controllable second actuator mechanism 8, which is not shown in detail. The second actuator mechanism 8 has, in particular, a hydraulic pump, an electromechanism attached to the hydraulic pump, and / or a hydraulic valve mechanism. Both actuator mechanisms 5 and 8 are attached to the wheel 3, respectively, and are consequently components of the wheel composite regulator 9 already described.

[0024] Finally, the automobile 1 further has at least one computer device 10, which is configured to coordinate and control, for example, actuator mechanisms 5,8 in order to carry out the method described below, at least in part, and especially in whole. The computer device 10 preferably has at least one, especially all, of the modules described below, and / or is configured to perform at least one of the functions listed below with respect to the lateral dynamics stabilization function already mentioned, or to perform a corresponding method step. The computer device 10 is configured in particular as an electronic control unit and / or control device (ECU).

[0025] As already mentioned, Figure 1 shows the mechanism for controlling the wheel composite controller 9 by stabilizing the lateral dynamics. To illustrate the method according to the present invention, various functions or modules (software and / or hardware), wiring related to the input and output amounts used as needed, and the actual wheel composite controller 9 are illustrated.

[0026] The lateral dynamics stabilization function of vehicle 1 in this example includes yaw rate control, designated as the first module 11, also known as vehicle dynamics control (VDC); trailer stabilization, designated as the second module 12, also known as trailer sway mitigation (TSM); and rollover prevention, designated as the third module 13, also known as rollover mitigation (ROM) or roll movement intervention (RMI).

[0027] What all functions or modules 11-13 have in common is vehicle motion (yawing velocity ψ, longitudinal acceleration α). x , lateral acceleration α y , and vehicle speed v x For the measurement of the steering angle (front axle steering angle δ), and the driver's steering preference. FA For the measurement of ), the provided sensor signals are used as input signals. For the control of the wheel-type regulator 9, it is important to know to what extent the electromechanism 6 of the first actuator mechanism 5, i.e., the drive motor, should be utilized.

[0028] For this purpose, the yawing moment potential is determined for this regulator. The yawing moment potential is determined from a physical wheel model (e.g., the Pacejka wheel model known from the literature) and a two-wheel model for automobile 1, which is denoted as a common fourth module 14. The wheel model takes the slip limit λ as an input quantity. Elec,minreceives this, which characterizes the slip limit of the wheel 3 during braking by the electro-mechanical machine 6.

[0029] The moment limit M obtained as the output force from the wheel model Elec,min is used as the input force in the fifth module 15 using the two-wheel model, where the first and second yaw moment limits M z,Elec,pos,max and M z,Elec,neg,max about the height axis are converted. Here, the first yaw moment limit M z,Elec,pos,max represents the maximum possible yaw moment in the clockwise (pos) direction, and the second yaw moment limit M z,Elec,neg,max represents the maximum possible yaw moment in the counterclockwise (neg) direction.

[0030] These yaw moment limits M z,Elec,pos,max and M z,Elec,neg,max enter the yaw moment distribution expressed as the sixth module 16, together with the first yaw moment ratio M z,VDC as the output force of the first module 11 and the second yaw moment ratio M z,TSM as the output force of the second module 12.

[0031] In the yaw moment distribution, the yaw moment ratios M z,VDC and M z,TSM as the input force or requirement are compared with the yaw moment limits M z,Elec,pos,max and M z,Elec,neg,max for the electro-mechanical machine 6.

[0032] If the requirement is lower than the yaw moment limit M z,Elec,pos,max or M z,Elec,neg,max the entire requirement is converted to the provisional first brake torque ratio M Elec,Mz for the electro-mechanical machine 6 of the first actuator mechanism 5. On the other hand, the yaw moment limit M z,Elec,pos,max or M z,Elec,neg,maxIf one of them is higher, in addition, the provisional second brake torque ratio M for the second actuator mechanism 8 of the hydraulic brake Hyd,Mz This is also calculated.

[0033] At the regulator mediation, designated as module 17, all brake torque ratios for the lateral dynamics stabilization function of the wheel composite regulator 9 converge. Here, the provisional first brake torque ratio M is the output amount of module 16. Elec,Mz and the provisional second brake torque ratio M Hyd,Mz In addition, the third brake torque ratio M is the output amount of the third module 13. Rom These are also used as input quantities.

[0034] In modules 16 and 17, the overall brake torque M at wheel 3 is determined in the first step, depending on the brake request. Rad The degree to which it is high is specified. In the next step, the actual, or final, brake torque ratio M is determined. Elec The first actuator mechanism 5 is connected to the electromechanical 6, and the final brake torque ratio M Hyd This specifies whether the second actuator mechanism 8 of the hydraulic brake is engaged. In this example, this refers to the moment limit M obtained as an output quantity from the wheel model, which is another input quantity in module 17. Elec,min This is done using the following method. The sum of the brake torque ratios of both wheels is equal to the brake torque M at wheel 3. Rad It corresponds to this.

[0035] The structure selected here, in particular, the functional division between modules 16 and 17, is derived from the functional architecture with the aim of separating requirements between the vehicle level (yawing moment) and the wheel level (wheel moment). This allows for the stabilization function of the driving dynamics to be coordinated in the right places and in a favorable manner.

[0036] The lower slip control for the second actuator mechanism 8, designated as the eighth module 18, is the input quantity from the seventh module 17 to the final second brake torque ratio M. Hyd In addition, slip limit λ Hyd It receives, and also receives hydraulic pressure p from wheel 3. Hyd Wheel rotation speed ω for control Rad The lower rotational speed control for the electromechanical 6 of the first actuator mechanism 5, which is designated as the ninth module 19, receives the final first brake torque ratio M from the seventh module 17 as an input quantity. Elec In addition, slip limit λ Rad,lim The rotational speed limit ω obtained from this Elec Received, and also, brake torque ratio M Elec For control of the wheel rotation speed ω from wheel 3 Rad The controllers below receive this information. Both lower-level controllers then act to ensure that the requested limits are adhered to.

[0037] Modules 17 to 19 form the core of the method according to the present invention, as described below. At this time, each of the actuator mechanisms 5 and 8 is assigned at least one slip limit value, in particular wheel-specific, i.e., in this example, at least the first actuator mechanism 5 is assigned a slip limit value λ Rad,lim The slip limit value is set to the second actuator mechanism 8, and the slip limit value λ is set to the second actuator mechanism 8. Hyd This is assigned as another slip limit value. Slip limit value λ Elec,min This is also considered as yet another slip limit value. Furthermore, the actuator mechanisms 5 and 8 are controlled depending on the slip limit value set each time in order to satisfy the braking requirement.

[0038] Next, we will explain, with reference to three examples, how the brake torque distribution mediated by the regulator in module 17 and the corresponding control by slip control and rotational speed control in modules 18 and 19 are performed within the framework of this method.

[0039] Here, at least four different slip limit values ​​are used, including the three slip limit values ​​already mentioned. For convenience, these are numbered in ascending order of their values ​​below, but this numbering is for distinction only and does not indicate any prioritization or setting, nor does it imply any necessary interdependence between the limit values.

[0040] Preferably, at least one of the slip limit values ​​is set depending on the capabilities of each actuator mechanism 5,8 and / or in particular on the driving mode of the automobile 1, including comfort mode and / or sport mode.

[0041] Figures 2 to 4 show the torque and slip transitions under various different driving conditions during the implementation of this method. In Figures 2 to 4, the upper half shows the graph of the moment M transition with respect to time t, and the lower half shows the graph of the wheel slip λ transition with respect to time t.

[0042] Figure 2 shows a first example including the temporal progression of brake torque distribution with a stable wheel slip progression. Figure 3 shows a second example including the temporal progression of brake torque distribution with an unstable wheel slip progression and active (electric) rotational speed control. Figure 4 shows a third example including the temporal progression of brake torque distribution with an unstable wheel slip progression and active (hydraulic) slip control and (electric) rotational speed control.

[0043] The numbering of each point in time described below has been chosen so that at least approximately the same thing occurs at the same time, in order to allow for better comparison of the illustrated examples.

[0044] First, the vehicle is monitored for brake requests. The actual slip value of the wheel slip λ is determined each time, and as soon as a corresponding brake request is recognized, only the first actuator mechanism 5 is controlled in accordance with the actual slip value, particularly by the rotational speed control of the electromechanism 6, to generate an electric brake torque.

[0045] That is, at time t0, the operation of the electromechanism 6 of the first actuator mechanism 5 is initiated each time. The first brake torque ratio M increases Elec However, this is applied to the electric machine 6. Wheel slip also continues to increase. The first brake torque ratio M Elec This corresponds to the torque of an electric brake.

[0046] A first slip limit value is then set and assigned to the second actuator mechanism 8. When the actual slip value reaches at least the first slip limit value, and especially when it exceeds it, the second actuator mechanism 8, in particular the electromechanism attached to the hydraulic pump, is additionally controlled to pre-fill the hydraulic circuit of the wheel brake device 7.

[0047] Figure 2 shows the slip limit λ. Hyd,Vor From the point t1 onward, an additional constant brake torque M is applied. Hyd,Vor It can be seen that the hydraulic wheel brake system 7 is set to be hydraulically pre-filled up to time t2. This avoids a potential weakness of the hydraulic wheel brake system 7 during pressure generation. Slip limit λ Hyd,Vor This corresponds to the first slip limit value.

[0048] This is specifically selected to be of a size that allows for reliable contact with the brake lining, and is defined, for example, depending on the hydraulic pressure value, particularly within the range up to 10 bar, for example to 5 bar, and / or depending on the cp characteristic value of the friction brake.

[0049] Furthermore, a second slip limit is set and assigned to the second actuator mechanism 8. When the actual slip value reaches at least the second slip limit, and especially when it exceeds it, the second actuator mechanism 8 is controlled to generate additional hydraulic brake torque.

[0050] Otherwise, control is performed electrically only until time t2, that is, the first actuator mechanism 5 is used, which is the slip limit λ already used in the wheel model. Elec,min This is the limit of the slip limit λ. Elec,min This corresponds to a second slip limit. The second slip limit is consequently greater than the first slip limit.

[0051] Electromechanical control is performed, in particular, using a target torque derived from the slip limit. The slip limit leads to the maximum moment. When the overall braking requirement is within this range, this maximum moment is adjusted as the target moment.

[0052] Slip limit λ at time t2 Elec,min It reaches or exceeds this. And the second brake torque ratio M continues to increase. Hyd However, it is supplied to the hydraulic wheel brake system 7 by the second actuator mechanism 8 and controlled hydraulically accordingly. Second brake torque ratio M Hyd This corresponds to additional hydraulic brake torque.

[0053] Furthermore, a third slip limit value is set and assigned to the first actuator mechanism 5. When the actual slip value reaches at least the third slip limit value, and especially when it exceeds it, the first actuator mechanism 5 is controlled to comply with the third slip limit value, and in particular to reduce the actual slip value to the third slip limit value.

[0054] Figure 2 shows the slip limit λ reached at time t3. Rad,limUp to this point, we can see that the second actuator mechanism 8 is controlled. Since this slip limit is not exceeded, the first actuator mechanism 5 also does not perform control. At this point, the slip limit λ Rad,lim This corresponds to the third slip limit. The third slip limit is consequently larger than the first and second slip limits.

[0055] In the example described, the overall braking requirement is higher than the maximum moment for the electromachine 6, and therefore the remaining moment ratio is set as the target moment for the wheel brake device 7. The target slip for machine 6 is the slip limit λ Elec,min The slip region is limited by the slip limit λ. The target slip for the wheel brake device 7 is the slip limit λ. Rad,lim Slip limit λ Elec,min This is brought about by the defined increase.

[0056] The target slip settings for each actuator mechanism 5 and 8 serve primarily to ensure the moment setting is correct. The adjustment signal for each actuator mechanism 5 and 8 is always moment. Only in cases where the wheel slip exceeds the target slip setting for each actuator mechanism 5 and 8 does the lower-level wheel controller become active, limiting the wheel slip to the target slip setting. This is explained in more detail in Figures 3 and 4.

[0057] Furthermore, a rotational speed limit value for the electromachine 6 of the first actuator mechanism 5 is set depending on the third slip limit value, and when the third slip limit value is reached or exceeded, the electromachine 6 is controlled by rotational speed control depending on the rotational speed limit value.

[0058] At this time, the slip limit λ Rad,lim Therefore, the rotational speed limit ω that has already been mentioned Elec This is given for the electric machine 6. At this time, the rotational speed limit ωElec This corresponds to the rotational speed limit for the electrical machine 6.

[0059] Finally, a fourth slip limit is set and assigned to the second actuator mechanism 8. When the actual slip value reaches at least the fourth slip limit, and especially when it exceeds it, the second actuator mechanism 8, and in particular the hydraulic valve mechanism, are controlled to comply with the fourth slip limit, and in particular to reduce the actual slip value to the fourth slip limit.

[0060] In this example, the slip limit λ, which was also mentioned earlier, is used for this purpose. Hyd An additional setting is added, which is always the slip limit λ Rad,lim Higher than, and preferably, the slip limit λ Rad,lim It is materialized with a limited offset relative to this. At this time, the slip limit λ Hyd This corresponds to the fourth slip limit. The fourth slip limit is therefore greater than the first, second, and third slip limits. Both slip limits λ Rad,lim and λ Hyd In this example, this has been followed, and therefore no further control is necessary.

[0061] In Figure 2, the slip limit λ Rad,lim As indicated by the lateral portion of the wheel slip transition, it lies in a linear or stable region of the slip curve for wheel 3. The slip and the above moment remain constant until time t6, after which they decrease again.

[0062] The method of brake torque distribution is to distribute the total brake torque M after time t6. Rad Figure 2 clearly shows that the process proceeds in the reverse order when it returns. First, up to time t7, the second brake torque ratio M Hyd However, the above-mentioned constant brake torque M for pre-filling Hyd,Vor It will decrease to that point.

[0063] Accordingly, the first brake torque ratio MElec This decreases. When and for how long the individual brake torque ratios decrease will become clear from the slip limits already explained. In this way, the slip limit λ is reached at time t8. Hyd,Vor It reaches again, and additional brake torque M Hyd,Vor This becomes unnecessary. Finally, at time t9, the brake requirement is fully met, and the first brake torque ratio M Elec It decreases to zero.

[0064] The brake torque distribution shown in Figure 2 demonstrates that this sequence allows for earlier and undetectable stabilization of lateral dynamics compared to conventional methods, because the electromechanical 6 of the drive unit 4 is utilized first. The wheel brake system 7 is also optimally incorporated, as the pressure generation dynamics are improved by pre-filling, and the perceptible NVH behavior of the brake fluid system only occurs at a later point in time.

[0065] Figure 3 shows the brake torque distribution, which has already been explained. Similarly, control is performed electrically from time t0 to time t2, pre-filling is performed hydraulically from time t1 to time t2, and control is performed hydraulically from time t2 onward.

[0066] Here, the slip limit λ Rad,lim However, the critical, or minimum, slip value λ μ,min Since it is located in the unstable region of the slip curve below this value, an unstable wheel slip transition is observed in the hydraulic control region. Therefore, at time t3, the slip limit λ Rad,lim The slip limit λ is exceeded during hydraulic control. Rad,lim In order to ensure compliance, the electrical control stage of machine 6 is set to the rotational speed limit ω Elec It follows.

[0067] Consequently, the case described above, in which the actual slip value exceeds the third slip limit value, begins. In response, the first actuator mechanism 5 is controlled in this example depending on the rotational speed limit value by rotational speed control, particularly to reduce the actual slip value to the third slip limit value, in order to comply with the third slip limit value.

[0068] At time t5, the slip limit λ Rad,lim is again at least approximately complied with, or the wheel slip varies only slightly around the slip limit λ Rad,lim until time t6. The slip limit λ Hyd is complied with or not exceeded. The rotational speed control is successful in that regard, and only the first brake torque ratio M Elec is modulated between times t5 and t6, while the second brake torque ratio M Hyd is kept constant.

[0069] That is, the control to comply with the third slip limit value ends immediately when the actual slip value falls below the slip limit value.

[0070] According to FIG. 2, after time t6, the second brake torque ratio M Hyd decreases to a constant brake torque M Hyd,Vor until time t7. Subsequently, the first brake torque ratio M Elec decreases, and at time t8, the additional brake torque M Hyd,Vor becomes unnecessary, and at time t9, the first brake torque ratio M Elec is reduced to zero.

[0071] In FIG. 4, the brake torque distribution already described can be seen again. From time t0 to time t2, electric control is performed, from time t1 to time t2, hydraulic precharging is performed, and after time t2, hydraulic control is performed.

[0072] The slip limit λ Rad,lim again becomes the minimum slip value λ μ,minSince it is in the unstable region of the slip curve below, an unstable wheel slip transition appears in the hydraulic control region. Therefore, at time point t3, the slip limit λ Rad,lim is exceeded during hydraulic control. In order to comply with the slip limit λ Rad,lim , the stage of the electric control of the machine 6 follows the rotational speed limit ω Elec .

[0073] Along with that, the case described above where the actual slip value exceeds the third slip limit value starts again. Accordingly, the first actuator mechanism 5 is controlled depending on the rotational speed limit value by rotational speed control, especially to lower the actual slip value to the third slip limit value, in order to comply with the third slip limit value.

[0074] However, there is a characteristic that the instability becomes more intense as the slip limit λ Hyd is exceeded during hydraulic control at time point t4. Therefore, a short stage in which the wheel slip is hydraulically controlled continues until time point t5 until the wheel slip falls below the slip limit λ Hyd again. In parallel with this, in order to also comply with the slip limit λ Rad,lim , the stage of electric control is carried out. In that limit, between time points t4 and t5, both the first brake torque ratio M Elec and the second brake torque ratio M Hyd are modulated.

[0075] Along with that, the case described above where the actual slip value exceeds the fourth slip limit value starts. Accordingly, additionally, the second actuator mechanism 8, especially the hydraulic valve mechanism, is also controlled to comply with the fourth slip limit value, especially to lower the actual slip value to the fourth slip limit value.

[0076] After time point t5, the slip limit λ Rad,lim is again at least approximately complied with, or the wheel slip reaches the slip limit λ Rad,lim by time point t6.It fluctuates only slightly around this point. The combined slip control and rotational speed control by both actuator mechanisms 5 and 8 are successful. Between time points t5 and t6, the first brake torque ratio M Elec Only the second brake torque ratio M is modulated. Hyd It remains constant.

[0077] The controls for ensuring compliance with the third and fourth slip limits terminate immediately if the actual slip value falls below the respective slip limit.

[0078] According to Figures 2 and 3, the second brake torque ratio M is used from time t6 until time t7. Hyd A constant brake torque M Hyd,Vor It decreases to the first brake torque ratio M. Elec The brake torque decreases, and at point t8, additional brake torque M Hyd,Vor This becomes unnecessary, and at time t9, the first brake torque ratio M Elec It is reduced to zero.

[0079] Accordingly, the examples shown in Figures 3 and 4 illustrate the wheel slip control strategy of the present invention using the wheel composite controller 9, which is fully applicable, particularly when the wheel slip enters an unstable region, or when a certain amount of wheel slip is intentionally tolerated, for example in sport mode, and in other respects, the critical limits for each control are not exceeded, as shown in Figure 2. By selecting the slip limit, it is ensured that the wheel slip is controlled primarily through the electromechanical 6. This allows for the desirable utilization of characteristics such as high dynamics and rapid controllability. [Explanation of symbols]

[0080] 1. Automobile 2 Axles 3 wheels 4. Electric drive system 5. First actuator mechanism 6. Electrical machinery 7. Wheel brake system 8. Second Actuator Mechanism 10 Computer Devices λ Wheel slip λ Hyd,Vor ,λ Elec,min ,λ Rad,lim ,λ Hyd Slip limit value M Elec Electric brake torque ω Elec Rotation speed limit

Claims

1. A method for operating an automobile (1), - The automobile (1) has at least one axle (2) having at least one wheel (3), - The wheel (3) is attached to an electrically operated drive unit (4) having a controllable first actuator mechanism (5) which has an electromechanism (6), - The wheel (3) is equipped with a wheel brake device (7) having a controllable second actuator mechanism (8). In the method, - Each of the actuator mechanisms (5, 8) has at least one slip limit value (λ), particularly wheel-specific. Ｈｙｄ，Ｖｏｒ , λ Ｅｌｅｃ，ｍｉｎ , λ Ｒａｄ，ｌｉｍ , λ Ｈｙｄ ) was assigned, - The actuator mechanism (5, 8) satisfies the brake requirement by setting a slip limit value (λ Ｈｙｄ，Ｖｏｒ , λ Ｅｌｅｃ，ｍｉｎ , λ Ｒａｄ，ｌｉｍ , λ Ｈｙｄ A method characterized by being controlled by a )

2. The method according to claim 1, wherein the wheel brake device has a separate electromechanism and / or the wheel brake device is a hydraulic wheel brake device having an electromechanism attached to a hydraulic pump and / or a hydraulic valve mechanism.

3. The slip limit value (λ Ｈｙｄ，Ｖｏｒ , λ Ｅｌｅｃ，ｍｉｎ , λ Ｒａｄ，ｌｉｍ , λ Ｈｙｄ ), at least one of which is set depending on the capabilities of each of the actuator mechanisms (5, 8) and / or depending on the driving mode of the motor vehicle (1) including in particular the comfort mode and / or the sports mode, method according to any one of claims 1 or 2.

4. The actual slip value of the wheel slip (λ) is determined, and first, only the first actuator mechanism (5) controls the rotational speed of the electromachine (6) in particular, and the electric brake torque (M) depends on the actual slip value. Ｅｌｅｃ The method according to any one of claims 1 to 3, characterized in that it is controlled for the generation of ).

5. First slip limit value (λ Ｈｙｄ，Ｖｏｒ ) is set and assigned to the second actuator mechanism (8), and the actual slip value is set to the first slip limit value (λ Ｈｙｄ，Ｖｏｒ The method according to claim 4, characterized in that when at least a certain value is reached, and especially when it is exceeded, the second actuator mechanism (8), and in particular the electromechanism attached to the hydraulic pump, is additionally controlled to pre-fill the hydraulic circuit of the wheel brake device (7).

6. The second slip limit value (λ Ｅｌｅｃ，ｍｉｎ ) is set and assigned to the second actuator mechanism (8), and the second slip limit value (λ Ｅｌｅｃ，ｍｉｎ ) is especially the first slip limit value (λ Ｈｙｄ，Ｖｏｒ ) is greater than the actual slip value (λ) of the second slip limit value. Ｅｌｅｃ，ｍｉｎ When the pressure reaches at least, and especially exceeds, the second actuator mechanism (8) applies an additional, particularly hydraulic, brake torque (M Ｈｙｄ The method according to any one of claims 4 or 5, characterized in that it is controlled for the generation of ).

7. The third slip limit value (λ Ｒａｄ，ｌｉｍ ) is set particularly in the unstable region of the wheel slip curve and assigned to the first actuator mechanism (5), and the third slip limit value (λ Ｒａｄ，ｌｉｍ ) in particular the first and / or second slip limit values ​​(λ Ｈｙｄ，Ｖｏｒ , λ Ｅｌｅｃ，ｍｉｎ ) is greater than the actual slip value (λ) of the third slip limit value. Ｒａｄ，ｌｉｍ When the value reaches at least, and especially when it exceeds, the first actuator mechanism (5) enters the third slip limit value (λ Ｒａｄ，ｌｉｍ In order to comply with the third slip limit value (λ), in particular, the actual slip value is used. Ｒａｄ，ｌｉｍ The method according to any one of claims 4 to 6, characterized in that it is controlled to lower to ).

8. The third slip limit value (λ Ｒａｄ，ｌｉｍ ) depends on the rotational speed limit value (ω) of the electromechanism (6) of the first actuator mechanism (5). Ｅｌｅｃ ) is set, and the electric machine (6) is set to the rotational speed limit value (ω Ｅｌｅｃ The method according to claim 7, characterized in that it is controlled by rotational speed control depending on ).

9. The fourth slip limit value (λ Ｈｙｄ ) is set and assigned to the second actuator mechanism (8), and the fourth slip limit value (λ Ｈｙｄ ) in particular the first, second, and / or third slip limit values ​​(λ Ｈｙｄ，Ｖｏｒ , λ Ｅｌｅｃ，ｍｉｎ , λ Ｒａｄ，ｌｉｍ ) is greater than the actual slip value (λ) of the fourth slip limit value. Ｈｙｄ When the slip reaches at least the fourth slip limit value, and especially when it exceeds it, the second actuator mechanism (8), and especially the hydraulic valve mechanism, in order to comply with the fourth slip limit value, particularly the slip actual value, and especially the slip actual value, and the slip actual value (λ Ｈｙｄ The method according to any one of claims 4 to 8, characterized in that it is controlled to lower to ).

10. The third and / or fourth slip limit value (λ Ｒａｄ，ｌｉｍ , λ Ｈｙｄ The control to ensure compliance with the slip limit value (λ) is such that the actual slip value is equal to the respective slip limit value. Ｒａｄ，ｌｉｍ , λ Ｈｙｄ The method according to any one of claims 7 to 9, characterized in that it terminates immediately when the value falls below )

11. A computer program product for execution on a computer device (10), characterized in that the computer program product implements the method described in any one of claims 1 to 10 when used in a manner appropriate to its intended purpose.

12. A machine-readable storage medium having the computer program product described in claim 11.

13. A computer device (10) for an automobile (1), particularly an electronic control device and / or control device, wherein the computer device (10) is specially set up to run the computer program product described in claim 11.

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