Electronic brake system for a motor vehicle, motor vehicle, and method for operating an electronic brake system

Abstract

The invention relates to a device belonging to an electronic brake system (12) for a motor vehicle (10), comprising at least one first sensor (20, 22) for detecting a brake input on a brake pedal (14) of the motor vehicle (10); at least one first electronic computing device (16) for generating a control signal (36) on the basis of the detected brake input; and at least one brake device (28, 30, 32, 34) for actuating a brake on the basis of the generated control signal (36), an additional electrical switching element (38) being provided which additionally generates a digital control signal (40) to actuate the brake device (28, 30, 32, 34). The invention also relates to a motor vehicle (10) and to a method for operating an electronic brake system (12).

Description

[0001] Electronic braking system for a motor vehicle, motor vehicle, and method for operating an electronic braking system

[0002] The invention relates to an electronic braking system for a motor vehicle, comprising at least one sensor for detecting a braking input at a brake pedal of the motor vehicle, at least one first electronic computing unit for generating a control signal depending on the detected braking input, and at least one braking device for controlling the brake depending on the generated control signal. The invention further relates to a motor vehicle with an electronic braking system and a method for operating an electronic braking system.

[0003] Electronic braking systems are already known from the prior art. These systems typically involve, for example, a sensor detecting a person's application of the brake pedal, transmitting the detected signal to an electronic processing unit, and then electronically sending a corresponding control signal to a braking device, particularly a brake caliper. Braking then occurs based on this control signal. However, to ensure sufficient reliability, a redundant system is necessary to maintain a basic braking function, such as for a minimum-risk maneuver, even in the event of a failure of the electronic braking system.

[0004] EP 2 964499 relates to a brake actuation unit for a "break-by-wire motor vehicle braking system" with a brake pedal-operated master brake cylinder.

[0005] DE 10 2004 055440 B4 relates to a motor vehicle braking system comprising a first master cylinder with a first piston that moves in accordance with a brake application by the driver.

[0006] The object of the present invention is to provide an electronic braking system, a motor vehicle, and a method by which a simple redundant braking capability for the motor vehicle is provided. This object is achieved by an electronic braking system, a motor vehicle, and a method according to the independent claims. Advantageous embodiments are specified in the dependent claims.

[0007] One aspect of the invention relates to an electronic braking system for a motor vehicle, comprising at least a first sensor for detecting a braking input at a brake pedal of the motor vehicle, comprising at least a first electronic computing device for generating a control signal depending on the detected braking input, and comprising at least one braking device for controlling a brake depending on the generated control signal.

[0008] It is provided that an additional switching element is included, which additionally generates a digital control signal for controlling the braking device, so that in the event of a fault, at least one braking device can be controlled based on the additional control signal.

[0009] In particular, this provides a robust fallback system should, for example, a fault occur within the electronic braking system. Specifically, the digital control signal can then actuate the braking device accordingly. The electronic braking system is a so-called break-by-wire system. This eliminates the need for mechanical connections between the individual units. Specifically, the electronic control unit is designed to generate corresponding control signals based on the braking input. Should a fault occur in this communication, a robust fallback system is essential. This is provided by the additional switching element.The switching element can be, in particular, a Hall sensor or a rotation sensor, which can generate a digital control signal. The braking system is then controlled based on this digital control signal. This allows, for example, basic braking functions to be performed using a digital control signal.

[0010] In particular, a braking request via the brake pedal can thus be provided with significantly reduced technical effort and bypassing the first electronic processing unit. This provides a robust function as an additional fallback option. Specifically, the mechanical fallback option is thus replicated using simple electronic means, especially a digital switch, such as the braking via a push button of the electric parking brake.

[0011] This is particularly evident in the prior art, for example, in the event of a failure of a main path via the electronic computing device, such that a safe minimum-risk maneuver can no longer be performed because the fault robustness is no longer sufficient. According to the invention, it is now possible to move the vehicle with sufficient safety due to the additional, robust redundancy level. This provides, among other things, the possibility of parking the vehicle in a safe location.

[0012] In particular, the additional electrical switching element is thus provided as a bypass to the primary electronic processing unit. This bypass acts as a fallback function and can be monitored even when the brake control system is functioning correctly. The bypass can be continuously validated against the inputs from the pedal sensors, and vice versa. This can be particularly useful in situations where there is a stalemate in fault detection.

[0013] According to an advantageous embodiment, at least a three-stage digital signal is generated depending on the detected braking force during brake input, and the control signal for at least one braking device is generated based on this signal. This prevents, for example, an immediate maximum braking action. Depending on the brake input, a force can be applied to the brake in stages, allowing for smoother braking. The term "three-stage" specifically means that no braking occurs in the first stage, gentle braking is applied in the second stage, and full braking is applied in the third stage. This is particularly dependent on the corresponding control signal. Naturally, more than three stages can also be provided.

[0014] Furthermore, it has proven advantageous if an electrical voltage for the electrical switching element is provided by at least one braking device. The braking device is, in particular, a brake caliper. Each brake caliper preferably has its own voltage source. This voltage source can then be used to provide voltage for the electrical switching element. Thus, an additional voltage source is not required, as the voltage is already provided by the braking devices.

[0015] It has proven advantageous to have a brake function stored in the braking system, whereby the braking function is executed when the braking system is activated via the electrical switching element. In other words, the digital control signal does not directly generate a brake signal. Instead, a function is stored that determines how braking should be performed when the braking system receives the digital control signal. For example, a predefined deceleration torque can be provided via this function. If the digital control signal is then transmitted to the braking system, deceleration is carried out according to the stored function. This allows for a simple yet robust basic braking function for the vehicle.

[0016] It has also proven advantageous to have the braking effect of the braking system set depending on the duration of the digital control signal. This can also be achieved via the stored braking function. For example, the intensity of the braking effect can be adjusted depending on the duration. For instance, the longer the digital control signal is present, the more intense and powerful the deceleration of the vehicle. This allows for a simple fallback option.

[0017] It has also proven advantageous to have at least one second electronic processing unit, designed to control the braking system. In other words, the electronic braking system has, for example, at least one second sensor designed to detect a braking input from the brake pedal. This second electronic processing unit is designed to generate a control signal based on the detected braking input and transmit it to the braking system. In particular, the second electronic processing unit serves as a first fallback for the first. The additional switching element is only activated if, for example, both the first and second electronic processing units have failed.In particular, if at least one error is detected in the first main path via the first electronic computing unit and a second error is detected in the second main path via the second electronic computing unit, the digital control signal is triggered. This further increases safety.

[0018] It should be noted here that a motor vehicle, in particular, can have at least four braking devices. As already mentioned, these braking devices are primarily brake calipers. In other words, each wheel of the motor vehicle has its own separate and independent braking device, which can be controlled separately via the main paths of the electronic computing devices as well as via the digital control signal.

[0019] In a further advantageous embodiment, the braking system performs an emergency maneuver for the vehicle based on the digital control signal. In particular, the emergency maneuver can be designed with a basic braking function, for example, as a so-called minimum-risk maneuver. In other words, the braking system can initiate braking in such a way that, for example, the vehicle can be brought to a stop at the roadside. The fallback function can be triggered via the familiar control element (brake pedal), with the deceleration being adjustable through different levels. This increases road safety.

[0020] It has also proven advantageous if the first electronic computing unit is designed to monitor communication between the first sensor, the first electronic computing unit, and the braking device, and if a fault is detected based on this monitoring. Thus, faults within the electronic braking system can be monitored internally via the electronic computing unit. In the event of a fault, the digital control signal can then generate a braking effect at the braking device.

[0021] Another aspect of the invention relates to a motor vehicle with an electronic braking system according to the previous aspect.

[0022] Furthermore, the invention also relates to a method for operating an electronic braking system according to the preceding aspect. Communication between at least the first sensor, the first electronic computing unit, and the braking unit is monitored by means of the first electronic computing unit. Upon detection of a fault by the first electronic computing unit, a digital control signal for the braking unit is generated by means of the additional electrical switching element.

[0023] The presented method is, in particular, a computer-implemented method. Therefore, a further aspect of the invention relates to a computer program product with program code means which, when executed by the electronic computing device, cause the electronic computing device to carry out a method according to the preceding aspect. Furthermore, the invention also relates to a computer-readable storage medium with at least one computer program product according to the preceding aspect.

[0024] Advantageous designs of the electronic braking system are to be regarded as advantageous designs of the motor vehicle and the method. The electronic braking system and the motor vehicle possess tangible features to enable the method to be carried out.

[0025] A computing unit / electronic computing device can be understood, in particular, as a data processing device containing a processing circuit. The computing unit can therefore process data to perform arithmetic operations. This may also include operations to perform indexed access to a data structure, such as a lookup table (LUT).

[0026] The computing unit may, in particular, contain one or more computers, one or more microcontrollers, and / or one or more integrated circuits, for example, one or more application-specific integrated circuits (ASICs), one or more field-programmable gate arrays (FPGAs), and / or one or more systems on a chip (SoCs). The computing unit may also contain one or more processors, for example, one or more microprocessors, one or more central processing units (CPUs), one or more graphics processing units (GPUs), and / or one or more signal processors, in particular one or more digital signal processors (DSPs). The computing unit may also include a physical or virtual array of computers or other units of the aforementioned type.In various embodiments, the computing unit includes one or more hardware and / or software interfaces and / or one or more storage units.

[0027] A storage unit can be volatile data storage, for example as dynamic random access memory (DRAM) or static random access memory (SRAM), or as non-volatile data storage, for example as read-only memory (ROM), programmable read-only memory (PROM), erasable programmable read-only memory (EPROM), electrically erasable programmable read-only memory (EEPROM), flash memory or flash EEPROM, ferroelectric random access memory (FRAM), or magnetoresistive random access memory.It can be designed as MRAM (magnetoresistive random access memory) or as phase-change random access memory, PCRAM (phase-change random access memory).

[0028] Further features of the invention will become apparent from the claims, the figures, and the description of the figures. The features and combinations of features mentioned above in the description, as well as the features and combinations of features mentioned below in the description of the figures and / or shown in the figures, may be encompassed by the invention not only in the combinations specified, but also in other combinations. In particular, the invention may also encompass embodiments and combinations of features that do not have all the features of an originally formulated claim. Furthermore, the invention may encompass embodiments and combinations of features that go beyond or deviate from the combinations of features set out in the cross-references to the claims.

[0029] The single figure shows a schematic block diagram according to an embodiment of a motor vehicle with an embodiment of an electronic braking system.

[0030] The invention is explained in more detail below with reference to specific embodiments and associated schematic drawings. In the figures, identical or functionally equivalent elements may be designated with the same reference numerals. The description of identical or functionally equivalent elements is not necessarily repeated with respect to different figures.

[0031] Fig. 1 shows a schematic block diagram of an embodiment of a motor vehicle 10 with an embodiment of an electronic braking system 12. The electronic braking system 12 has a brake pedal 14, in particular in the form of an electronic brake pedal. In the following exemplary embodiment, the electronic braking system 12 further comprises a first electronic computing unit 16 and a redundant second electronic computing unit 18. The first electronic computing unit 16 communicates with a first sensor 20 and with a first second sensor 22 on the brake pedal 14.

[0032] The second electronic computing unit 18 communicates with a second first sensor 24 and with a second second sensor 26 on the brake pedal 14.

[0033] Furthermore, four braking devices 28, 30, 32 and 34 are shown in particular. Specifically, a first braking device 28, for example for a front left wheel, is shown. Furthermore, a second braking device 30 for a rear right wheel is shown. In addition, a third braking device 32 for a front right wheel is shown. Furthermore, a fourth braking device 34 for a rear left wheel is shown.

[0034] The first electronic computing unit 26 and the second electronic computing unit 18 communicate redundantly with the braking units 28, 30, 32 and 34. In particular, in the event of a failure of the main path via the first electronic computing unit 16, the second electronic computing unit 18 can again take over the braking of the motor vehicle 10.

[0035] In particular, Fig. 1 shows that the first sensors 20, 22 are designed to detect a brake input at the brake pedal 14. The first electronic computing unit 16 is in turn designed to generate a control signal 36 depending on the detected brake input and to transmit it to the brake devices 28, 30, 32, 34, thus controlling the brake devices 28, 30, 32, 34. Fig. 1 further shows that, according to the invention, an additional switching element 38 is provided which, in the event of a fault, generates a digital control signal 40 for controlling the brake devices 28, 30, 32, 34.

[0036] In particular, it is provided that at least one three-stage digital control signal 40 is generated depending on a detected braking force during brake input, and that, depending on this, the control signal 36 for the at least one brake device 28, 30, 32, 34 is generated. Furthermore, an electrical voltage for the electrical switching element 38 can be provided by the at least one brake device 28, 30, 32, 34. It can also be provided that a braking function 42 is stored in the brake device 28, 30, 32, 34, wherein the braking function 42 is executed when the brake device 28, 30, 32, 34 is activated via the electrical switching element 38. It can also be provided that a braking effect of the brake devices 28, 30, 32, 34 is set depending on the duration of the digital control signal 40.

[0037] Fig. 1 also shows that the second electronic computing device 18 can generate another control signal 44, which, for example, can first be generated when the first electronic computing device 16 fails, and which can then be transmitted to the braking devices 28, 30, 32, 34.

[0038] In particular, it may be provided that, on the basis of the digital control signal 40, the braking device 28, 30, 32, 34 is controlled to carry out an emergency maneuver of the motor vehicle 10.

[0039] The electronic switching element 38 is provided, in particular, for implementing a braking request via the brake pedal 14 with significantly reduced technical effort, bypassing the two main paths via the first electronic processing unit 16 and the second electronic processing unit 18. This provides a robust function as an additional fallback level. Specifically, it allows the simulation of a mechanical fallback level to be carried out by simple electronic means, such as the switching element 38 designed as a digital switch. According to the embodiment shown in Fig. 1, the background is that, for example, one or both of the two main paths via the first electronic processing unit 16 and the second electronic processing unit 18 fail, which leads to a redundancy level and necessitates the fastest possible shutdown of the vehicle 10, as the robustness against secondary faults is no longer sufficient.

[0040] The present invention enables the motor vehicle 10 to be moved with sufficient safety even at the robust redundancy level. This includes, among other things, the possibility of parking the motor vehicle in a safe position.

[0041] Reference symbol list

[0042] Motor vehicle electronic braking system

[0043] brake pedal first electronic computing unit second electronic computing unit first first sensor first second sensor second first sensor second second sensor first brake device second brake device third brake device fourth brake device

[0044] Control signal, electrical switching element, digital control signal

[0045] Brake function, further control signal

Claims

Patent claims 1. Electronic braking system (12) for a motor vehicle (10), comprising at least one first sensor (20, 22) for detecting a brake input at a brake pedal (14) of the motor vehicle (10), comprising at least one first electronic computing unit (16) for generating a control signal (36) depending on the detected brake input and comprising at least one braking device (28, 30, 32, 34) for controlling a brake depending on the generated control signal (36), characterized in that an additional electrical switching element (38) is provided which additionally generates a digital control signal (40) for controlling the braking device (28, 30, 32, 34).

2. Electronic braking system (12) according to claim 1, characterized in that at least one three-stage digital control signal (40) is generated depending on a detected braking force during brake input and depending on this the control signal (36) for the at least one braking device (28, 30, 32, 34) is generated.

3. Electronic braking system (12) according to claim 1 or 2, characterized in that an electrical voltage for the electrical switching element (38) is provided by the at least one braking device (28, 30, 32, 34).

4. Electronic braking system (12) according to one of the preceding claims, characterized in that a braking function (42) is stored in the braking device (28, 30, 32, 34), wherein the braking function (42) is carried out when the braking device (28, 30, 32, 34) is activated via the electrical switching element (38).

5. Electronic braking system (12) according to claim 4, characterized in that a braking effect of the braking device (28, 30, 32, 34) is set depending on a time duration of the digital control signal (40).

6. Electronic braking system (12) according to one of the preceding claims, characterized in that at least a second electronic computing device (18) is provided which is designed to control the braking device (28, 30, 32, 34).

7. Electronic braking system (12) according to one of the preceding claims, characterized in that, on the basis of the digital control signal (40), the braking device (28, 30, 32, 34) performs an emergency maneuver for the motor vehicle (10).

8. Electronic braking system (12) according to one of the preceding claims, characterized in that the first electronic computing device (16) is designed to monitor communication between the first sensor (20, 22), the first electronic computing device (16) and the braking device (28, 30, 32, 34), and a fault is detected depending on this monitoring.

9. Motor vehicle (10) with an electronic braking system (12) according to one of claims 1 to 8.

10. Method for operating an electronic braking system (12) according to any one of claims 1 to 8, comprising the steps: - Monitoring communication between at least the first sensor (20, 22), the first electronic computing device (16) and the braking device (28, 30, 32, 32) by means of the first electronic computing device (16); and - Upon detection of a fault by means of the first electronic computing unit (16), a digital control signal (40) is generated for the braking unit (28, 30, 32, 34) by means of the additional electrical switching element (38).

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