Device and method for operating a brake force generator

Abstract

The invention relates to a method for operating a brake force generator of a motor vehicle having a hydraulic brake system, wherein the brake force generator builds up a braking force independently in a first operating mode and builds up a braking force in a driver-assisted manner in a second operating mode, the method being characterized in that a strategy for operating the brake force generator is adapted as a function of the driving situation. In addition, a corresponding device is provided.

Description

Technical Field

[0001] The invention relates to a method for operating a brake force generator of a motor vehicle having a hydraulic brake system, wherein the brake force generator builds up a braking force independently in a first operating mode and builds up a braking force in a driver-assisted manner in a second operating mode, characterized in that a strategy for operating the brake force generator is adapted as a function of the driving situation. In addition, a corresponding device is provided. Background Art

[0002] From the prior art, vehicles are known that have at least one highly automated or autonomous driving function, which can at least partially take over the actual driving task. As a result, the vehicles can be driven in a highly automated or autonomous manner, in that they independently detect, for example, the course of the road, other road users or obstacles, and calculate corresponding control commands in the vehicle, and forward these control commands to actuators in the vehicle, thereby correctly influencing the driving course of the vehicle. In such highly automated or autonomous vehicles, the driver generally does not participate in the driving event. Nevertheless, measures and means are provided that enable the driver to intervene in the driving event at any time.

[0003] Furthermore, the following braking systems for vehicles are known from the prior art: the braking systems are designed to be controlled by the vehicle driver using hydraulic force measures (Durchgriff). This ensures that when the braking system fails, the driver can still apply sufficient braking force to the wheels of the vehicle by operating the brake pedal. This design has a decisive influence on the topology of current braking systems. In this way, by maintaining good performance in the strain level (Rueckfallebene), it is possible to justify the size of, for example, a series master brake cylinder. Furthermore, the braking system can be implemented as a so-called coupled braking system or a power-assisted braking system. However, these systems are also implemented so that: as a strain level, hydraulic force measures are given by the driver as always. Power-assisted braking devices are not suitable for highly automated or autonomous vehicles, because there, during the autonomous driving function, it is no longer the driver who is used to enhance in this regard, and the braking system must completely and independently build up braking energy.

[0004] A method for operating a hydraulically closed vehicle brake system is known from DE 10 2009 001 135 A1. The vehicle brake system comprises an electromechanical brake booster unit and a wheel slip control device. In this case, the vehicle brake system is operated with the brake booster unit in situations in which the brake pedal is not actuated, for example, to limit the vehicle speed or to adjust the distance to a vehicle traveling ahead or when parking.

[0005] Furthermore, ECE-R13 and Directive 98 / 12 / EG are known from the prior art. These documents relate to approval guidelines for brake systems in motor vehicles.

[0006] In a known manner, monitoring (software functions for fault detection) of electric brake booster units is parameterized in a vehicle-specific manner. In this case, a fault in the product must be detected within the deceleration range (defined via ECE-R13) and lead to a corresponding backup reaction. For example, a boundary condition in the parameterization is a defined brake pedal force (500 N) that is established by the vehicle driver. The calculation of the monitoring parameters is generally performed taking into account this defined brake pedal force. Summary of the invention

[0007] However, in certain driving situations, a different brake pedal force is actually present, or no brake pedal force is present either, such as is the case during autonomous driving or braking. When calculating the monitoring threshold, the robustness of the monitoring function (monitoring) (e.g. with respect to temperature changes, aging, etc.) is reduced by taking into account a brake pedal force that is not present (at the expected level). This also reduces the availability of the product. Advantageously, however, the method and device according to the invention make it possible to increase the availability of the brake system and therefore the vehicle.

[0008] This is achieved according to the invention by the features described in the first aspect of the invention. Other embodiments of the invention are the subject matter of the other aspects of the invention.

[0009] A method according to the invention for operating a brake force generator of a motor vehicle having a hydraulic brake system, wherein the brake force generator builds up a braking force independently in a first operating mode and builds up a braking force in a driver-assistive manner in a second operating mode, is characterized in that a strategy for operating the brake force generator is adapted as a function of the driving situation.

[0010] Any brake force generator that can independently build up a brake pressure as an external force brake and that can boost a pressure predefined by the driver as a brake booster unit is to be understood as a brake force generator. In particular, an electromechanical brake booster unit is to be understood as such a brake booster unit. For example, reference should be made to the so-called iBooster from Robert Bosch GmbH. However, the present invention is not limited to such a system and can include any other implementations, such as pneumatic or hydraulic brake force generators, in a similar manner.

[0011] Any settable control and / or any predefinable characteristic of the brake force generator may be understood as a strategy for operating the brake force generator. Examples include: pedal characteristics (e.g. for feedback to the driver), brake characteristics (e.g. dynamic range of brake pressure buildup), etc.

[0012] For example, a strategy for detecting defects in a brake force generator can also be understood as a strategy for operating the brake force generator. The strategy for detecting defects implemented as a software function is referred to as "monitoring" here. It is understood that the software function for detecting defects can be matched during the operation of the motor vehicle. Advantageously, in particular, it is provided that a specific threshold value can be matched under monitoring. The matching is based on factors described as driving conditions. In this case, external factors (such as temperature, friction coefficient value, etc.) can be involved, as well as internal factors (such as autonomous / manual operating mode of the motor vehicle) can be involved. With this understanding, the present invention can advantageously dynamically match the functional monitoring threshold according to the current driving condition of the vehicle. In this way, parameters that are more suitable for the driving condition and therefore more robust can be used for the electric brake booster unit, which minimizes the probability of defective degradation of the brake system components.

[0013] In an advantageous embodiment, the method is characterized in that, when adapting the strategy for operating the brake force generator, a parameterization of the operating function is changed.

[0014] This is understood to mean that the parameterization of the strategy for operating the brake force generator is adapted during operation of the motor vehicle and taking into account and as a function of the driving situation. For example, the strategy for fault detection is adapted in this case, wherein the parameterization of the fault detection function is changed in this case. Advantageously, the effectiveness of the fault detection is improved and thus the availability of the system is increased.

[0015] In a preferred embodiment, the method is characterized in that at least one value of a parameterized parameter of the operating function is adapted as a function of the respective driving situation.

[0016] This is understood to mean, for example, changing one or more monitored parameters situationally. Of course, it is also conceivable to adapt all parameters according to the present situation.

[0017] In an alternative embodiment, the method is characterized in that at least one value of a parameter of a parameterization of the operating function is selected from the stored data record.

[0018] This is understood to mean, for example, that one or more parameters of the monitoring are changed in a situational manner, wherein the parameters corresponding to the respective driving situation or suitable therefor are read out from the stored data record. Furthermore, the selected parameters are adopted and used accordingly in the current monitoring situation. Of course, it is conceivable that not only individual parameters of the parameterization are saved and read out, but also the entire parameterization for the fault detection function is saved and read out.

[0019] In an advantageous embodiment, the method is characterized in that at least one value of a parameterized parameter of the operating function is calculated.

[0020] This is understood to mean, for example, changing one or more parameters monitored situationally, wherein a parameter corresponding to or suitable for the respective driving situation is calculated situationally. Of course, it is also conceivable to calculate all parameters according to the present situation.

[0021] In a possible embodiment, the method is characterized in that the operating mode of the brake force generator is taken into account as the driving situation, in particular taking into account whether the brake force generator generates a braking force independently or a braking force which assists the driver's braking force in the current situation.

[0022] In a preferred embodiment, the method is characterized in that the operating mode of the brake generator is taken into account as the driving situation, in particular whether the brake generator in the current situation builds up a braking force independently or in a manner that assists the driver.

[0023] In an alternative embodiment, the method is characterized in that the information about the driving situation is transmitted via a common bus system.

[0024] This is understood to mean using a bus system already present in the motor vehicle in order to also transmit information about the current driving situation thereon. For example, this could be an existing bus line and bus communication between a central control device of an automated driving system and a control device of a brake force generator.

[0025] In a preferred embodiment, the method is characterized in that at least one first parameterization and a second parameterization for defect detection of the brake force generator are constructed, and at least one first driving condition and a second driving condition are defined, wherein the first parameterization is selected when the first driving condition is detected, and the second parameterization is selected when the second driving condition is detected.

[0026] In an advantageous embodiment, the method is characterized in that the strategy for operating the brake force generator is designed as a strategy for fault detection of the brake force generator, wherein in particular a parameterization of the fault detection function is changed when adapting the strategy for fault detection.

[0027] In one possible embodiment, the method is characterized in that, when adapting the strategy for fault detection, a parameterization of the fault detection function is determined in such a way that a fault detection which is as robust as possible is achieved for the respective driving situation.

[0028] This is understood to mean that, for the monitoring of the brake force generator, the most robust parameters for the driving operation are set. In addition, this means that, for example, when there are more options for parameterization, the option with the highest robustness for the current situation is selected.

[0029] In a possible embodiment, the method is characterized in that at least one first parameterization and a second parameterization for defect detection of the brake force generator are constructed; wherein in the first parameterization, a first monitoring threshold for detecting defects is defined without taking into account the driver's pedal force; and in the second parameterization, a second monitoring threshold for detecting defects is defined while taking into account a specific pedal force of the driver.

[0030] The method can be implemented, for example, in software or hardware or in a hybrid form of software and hardware, for example in a control unit.

[0031] The solution presented here also proposes a device, which is designed to execute, control or implement the steps of the variant of the method presented here in a corresponding device. The task on which the invention is based can also be solved quickly and efficiently by the embodiment variant of the invention in the form of a device.

[0032] In the present invention, a device can be understood as an electrical device that processes sensor signals and outputs control and / or data signals based on the sensor signals. The device can have an interface, which can be constructed in hardware and / or in software. In a hardware-based construction scheme, the interface can be, for example, a part of a so-called system ASIC that contains many different functions of the device. However, it is also possible that the interface is a dedicated integrated circuit or at least partially includes discrete components. In a software-based construction scheme, the interface can be, for example, a software module that is present on a microcontroller in addition to other software modules.

[0033] Furthermore, the present device is understood to include a control device, in particular a control device for operating a brake force generator and / or a control device for implementing an automated driving function. The present device is also understood to include a brake force generator that is configured to implement the present method. Of course, the present device is also understood to include a vehicle having a brake force generator for implementing the present method. In particular, this is understood to include a vehicle that can be operated both automatically and under driver control.

[0034] Also advantageous is a computer program product or a computer program with a program code, which can be stored on a machine-readable carrier or storage medium, such as a semiconductor memory, a hard disk memory or an optical memory, and which is used to execute, implement and / or control the steps of the method described in one of the embodiments described above, in particular when the program product or the program is implemented on a computer or a device. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] It should be pointed out that the features mentioned individually in the description can be combined with one another in any technically meaningful manner and represent further embodiments of the invention. Further features and suitability of the invention are apparent from the description of the exemplary embodiments with reference to the attached figures.

[0036] In these figures:

[0037] Figure 1 A schematic diagram showing a vehicle having a brake force generator according to an embodiment of the present invention; and

[0038] Figure 2 A diagram showing method steps for adapting parameterization according to an embodiment of the present invention; and

[0039] Figure 3 A diagram shows different profiles of a functional monitoring threshold value. DETAILED DESCRIPTION

[0040] Figure 1A schematic diagram of a vehicle with an electromechanical brake force generator according to an embodiment of the present invention is shown. The motor vehicle 1 is only indirectly shown via several components, such as, for example, via a drive motor 7 and a vehicle wheel 6 with a wheel brake. In addition, a hydraulic brake system 2 is counted as a component shown. The driver's braking desire can be recorded via a brake pedal 3. In addition, a brake force generator 4 is shown. The brake force generator 4 is designed to generate a braking force independently of the driver as an external force brake. In addition, the brake force generator 4 is designed to assist the driver's braking force as a servo brake. The brake force generator 4 includes a control device 4a for control. In addition, the brake force generator 4 includes an actuator 4b (for example, an electric motor) for generating a braking force. The brake force generator 4 also includes a transmission device 4c (for example, a spindle transmission (Spindelgetriebe)) for transmitting the generated force. The transmission device can also include a combination module for combining the force recorded via the brake pedal 3 and the force generated by means of the actuator 4b. With this force, for example, an adjustment piston. In addition, a master brake cylinder 4d (especially a tandem master brake cylinder) is provided. Here, for example, the mentioned piston adjustment is converted into a fluid movement or into a brake pressure build-up. In addition, the hydraulic brake system 2 can be preceded by a modulation unit 5, which modulates the hydraulic pressure present in the system as required. The modulation unit 5 can have a separate control device 5a. In addition, a central control device 8 is shown, which, for example, controls automated driving functions for the motor vehicle.

[0041] exist Figure 2, a diagram of the method steps for adapting parameterization according to an embodiment of the present invention is shown. In this case, in a first step S1, the method is started. In a second step S2, the driving mode of the vehicle (e.g., automated driving) is defined. This can be activated manually by the driver, for example. In step S3, information about the driving mode is transmitted. The transmission of data can be carried out with the aid of existing bus communication. In addition, the data is loaded into the control device of the brake force generator. Then, in condition B1, it can be checked whether there is an automated driving mode. If this is the case (Y branch), the corresponding braking mode is selected, for example, the HAD braking mode (Highly Automated Driving) is selected in step S4b. In this case, in the next step S5b, the monitoring threshold for automated driving is determined. For example, the corresponding monitoring threshold is read out from a database. In the next step S6, the determined monitoring threshold is applied and used during defect inspection. Subsequently, in condition B2b, it is checked whether the termination criteria for this method are met. If this is the case (Y branch), the method ends in step S7. If this is not the case (N branch), step S6b is continued. In this case, it is also checked at a defined time (or also continuously) whether condition B1 (dashed line) continues to be met. If condition B1 (N branch) is not met originally or at a later time, a corresponding alternative braking mode (e.g. for braking to assist the driver) is selected in step S4a. In this case, in the following step S5a, a monitoring threshold for driving determined for the driver is determined. For example, the corresponding monitoring threshold is read out from a database. In the following step S6a, the determined monitoring threshold is applied and used during the defect check. Subsequently, it is checked in condition B2a whether the termination criterion for the method is met, with consequences similar to those for condition B2b already described.

[0042] also, Figure 3 A diagram showing a number of variations of different functional monitoring thresholds is shown. The diagram shows, on the one hand, the braking force F of the master brake cylinder in relation to the driver's braking force F by means of a solid line. Driver (X axis) applied pressure variation process F out (Y axis on the left). Specifically, in this case the point “Jump-in” is marked in and click "run-out" out Also marked is the point where the driver's force is 500N, i.e. point F driver_500N In addition, two further graphs are shown: on the one hand, the dotted line d m_I , the point line d m_I The magnitude is shown to be 6.43 m / s 2This corresponds to the set value of the desired target deceleration. According to the prior art, this target deceleration is constant over the entire variation process. This variable is also constant in different driving situations. In addition, Figure 3 The dashed line d m_II , the dotted line d m_II The adapted medium vehicle deceleration is shown. The actually effective driver pedal force is taken into account when determining this variable. The curve diagram changes accordingly in its course. When defining the parameterization for fault detection, the characteristic variable d m_II Correspondingly, parameterized adaptation is also performed according to the corresponding driving conditions. For example, parameterized adaptation is performed according to the selected driving mode (automated driving vs. normal driving). Similarly, parameterized adaptation can also be performed according to the actual currently effective driver braking force, as shown above.

Claims

1. A method for operating a brake force generator (4) of a motor vehicle (1), the motor vehicle (1) having a hydraulic brake system (2), wherein the brake force generator (4) builds up a braking force independently in a first operating mode and builds up a braking force in a driver-assisting manner in a second operating mode, characterized in that: adapting the strategy for operating the brake force generator (4) according to the driving situation, wherein the strategy for operating the brake force generator (4) is designed as a strategy for detecting defects in the brake force generator (4), At least one first parameterization and a second parameterization of a fault detection function of the brake force generator (4) are constructed, and at least one first driving situation and a second driving situation are defined, wherein the first parameterization is selected when the first driving situation is detected, and the second parameterization is selected when the second driving situation is detected.

2. The method according to claim 1, characterized in that When adapting the strategy for operating the brake force generator (4), parameterization of operating functions is changed.

3. The method according to claim 1, characterized in that Depending on the respective driving situation, at least one value of a parameterized parameter of the operating function is adapted.

4. The method according to claim 1, characterized in that: At least one value for a parameterization of the operating function is selected from the stored data record.

5. The method according to claim 1, characterized in that At least one value of a parameterized parameter of an operating function is calculated.

6. The method according to claim 1, characterized in that The driving pattern of the motor vehicle (1) is taken into account as the driving situation.

7. The method according to claim 6, characterized in that Consideration is given to whether the motor vehicle (1) is being controlled by the driver in the current situation or whether the motor vehicle (1) is being driven automatically.

8. The method according to claim 1, characterized in that: The operating mode of the brake force generator (4) is taken into account as the driving situation.

9. The method according to claim 8, characterized in that Consider whether the brake force generator (4) builds up a brake force independently in the existing situation or builds up a brake force in a manner that assists the driver.

10. The method according to any one of claims 1 to 9, characterized in that: Information about the driving situation is transmitted via a common bus system (9).

11. The method according to any one of claims 1 to 9, characterized in that: When adapting the strategy for defect detection, the parameterization of the defect detection function is changed.

12. The method according to claim 11, characterized in that When adapting the strategy for fault detection, a parameterization of the fault detection function is determined in such a way that a fault detection which is as robust as possible for the respective driving situation is achieved.

13. The method according to claim 11, characterized in that In the case of the first parameterization, a first monitoring threshold for identifying defects is defined without taking into account the pedal force of the driver; and in the case of the second parameterization, a second monitoring threshold for identifying defects is defined taking into account a predetermined pedal force of the driver.

14. A device comprising a processor and a memory, the memory storing a computer program, the computer program being configured to implement the method according to any one of claims 1 to 13 when executed on the processor. 15 . A computer program product comprising a computer program which, when executed by a device according to claim 14 , is configured to carry out the method according to claim 1 .

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