Electromechanical brake and method for controlling a braking process

Abstract

An electromechanical brake (16) is specified, comprising at least one brake actuator unit (18) assigned to a vehicle wheel (12, 13, 14, 15), and a control unit (20) for controlling the brake actuator unit (18), wherein the control unit (20) comprises a microprocessor (24) having a first section (26) and a second section (28), wherein a first program code (Prg1) for triggering a restart of the control unit (20) is stored on the first section (26), and a second program code (Prg2) is stored in the second section (28), which, upon a restart of the control unit (20) and upon the presence of a brake command, controls the brake actuator unit (18) to brake the assigned vehicle wheel (12, 13, 14, 15). Furthermore, a method for controlling a braking process in a vehicle (10) with an electromechanical brake (16) is specified.

Description

[0001] The invention relates to an electromechanical brake with at least one brake actuator unit and a method for controlling a braking process in a vehicle with an electromechanical brake.

[0002] In electromechanical brakes, at least one brake actuator unit assigned to a vehicle wheel is controlled by a control unit to initiate a braking operation. For this purpose, suitable software is stored on a microprocessor in the control unit.

[0003] During driving, malfunctions can occur that trigger a reboot of the control unit. In particular, software errors or external influences, such as electromagnetic interference, can initiate a reboot of the control unit. In other cases, the malfunction can be triggered by a process in the software program, such as a division by zero.

[0004] If such a restart is initiated while braking is in progress, it may adversely affect the braking process.

[0005] It is therefore an object of the invention to maintain an already triggered braking process in a vehicle when a restart of the control unit is triggered.

[0006] This object is achieved according to the invention by an electromechanical brake with at least one brake actuator unit which is assigned to a vehicle wheel, and with a control unit for controlling the brake actuator unit, wherein the control unit comprises a microprocessor which has a first section and a second section, wherein a first program code for triggering a restart of the control unit is stored in the first section, and a second program code is stored in the second section which, when the control unit is restarted and when a brake command is present, controls the brake actuator unit to brake the assigned vehicle wheel.

[0007] The brake according to the invention has the advantage that the brake actuator unit is activated even when the control unit is restarted. Therefore, an ongoing braking process is not interrupted when the control unit is restarted, significantly improving driving safety. In other words, an emergency braking function is implemented using the second program code.

[0008] When the control unit is restarted by the first program code, the second program code can control the brake actuator unit to brake the associated vehicle wheel if a brake command is present. This means that during a restart, both the first program code and the second program code are executed if a brake command was present at the time of the restart.

[0009] For example, the second program code, once initiated by the restart and the brake command, runs independently of the first program code. This means that the execution of the second program code is not affected by the restart, allowing continuous control of the brake actuator unit.

[0010] Alternatively, the second program code can also be configured to trigger a restart of the control unit. More specifically, in this case, both the first program code and the second program code are configured to trigger a restart, with the second program code controlling the brake actuator unit to brake the associated vehicle wheel when a braking command is present and simultaneously triggering the restart. This is advantageous in terms of processing speed, since either only the first program code or only the second program code executes. In particular, the second program code only executes when a braking command is present.

[0011] Preferably, a separate microprocessor is provided for each vehicle wheel, which is equipped with the first program code and the second program code in separate, assigned sections. This further increases vehicle safety, since each brake actuator unit continues to be controlled when the vehicle is restarted during a braking operation.

[0012] The microprocessor can include a logic module with reset logic stored on it. This means the reset logic is located on a hardware component and thus less dependent on the software. This makes the reset logic less error-prone and ensures reliable operation even in the event of a software malfunction.

[0013] The reset logic is configured to trigger the execution of the first and second program code when the appropriate conditions are met, ie when a restart of the control unit is requested or when a brake command is present during a requested restart.

[0014] The object is further achieved according to the invention by a method for controlling a braking process in a vehicle with an electromechanical brake using a microprocessor. If the control unit of the electromechanical brake detects an electronic fault, the control unit checks whether a braking process is currently taking place. If no braking process is taking place, a restart of the control unit is triggered by executing a first program code stored in a first section of a microprocessor. If a braking process takes place, a restart of the control unit is triggered, and a braking process is initiated and controlled by a second program code stored in a second section of the microprocessor.

[0015] As already explained in connection with the electromechanical brake, this improves driving safety, especially since a braking process that is already in progress is not interrupted when the control unit is restarted, but continued or completed.

[0016] According to one embodiment, when a braking operation occurs, the restart of the control unit is triggered in the first section. More precisely, according to this embodiment, the restart is always triggered in the first section. In this case, only the brake actuator unit is controlled in the second section. This reduces the complexity of the software.

[0017] However, as already described above, it is conceivable that the program code stored in the second section is also suitable for triggering a restart.

[0018] The first program code is preferably independent of the second program code. This allows the restart to be triggered independently of the second program code, even when no brake command is present. In particular, a restart can be triggered in the first section even when there is no electronic fault.

[0019] The control unit can be restarted by an external reset signal or by an internal reset signal. The external reset signal is triggered in the control unit outside the microprocessor, and the internal reset signal is triggered in the microprocessor itself. An external reset signal is, for example, an ignition signal that triggers the control unit to boot up when the vehicle is started. An internal reset signal, on the other hand, is triggered by an electronic fault. This allows various influencing factors to be taken into account.

[0020] For example, a status signal is sent to a logic module in the microprocessor that stores reset logic when a braking operation occurs. The status signal can be either an internal status signal or an external status signal. The logic module uses the status signal to detect that a braking command is currently present and triggers the execution of the second program code accordingly. An external status signal is preferred here because it is independent of the microprocessor's software and therefore more reliable. If an electronic fault has already occurred in the microprocessor, necessitating a restart, the internal status signal may also be faulty.

[0021] When an electronic malfunction occurs, an error code is preferably stored in a program memory. This allows the malfunction to be subsequently analyzed and the microprocessor software to be revised and updated accordingly if necessary.

[0022] The process can run independently for each vehicle wheel on a dedicated microprocessor assigned to that wheel. As already mentioned, this further increases vehicle safety.

[0023] Further advantages and features will become apparent from the following description and the accompanying drawings, to which reference is made. The drawings show: - Fig. 1 schematically shows a vehicle with four wheels, each wheel being associated with an electromechanical brake according to the invention, and - Fig. 2 schematically shows a microprocessor of an electromechanical brake according to the invention.

[0024] Fig. 1 schematically illustrates a vehicle 10 with four brakeable vehicle wheels 12, 13, 14, 15 and with an electromechanical brake 16.

[0025] The electromechanical brake 16 comprises four brake actuator units 18, with each vehicle wheel 12, 13, 14, 15 being assigned a brake actuator unit 18.

[0026] The brake actuator units 18 can each be controlled to brake the associated vehicle wheel 12, 13, 14, 15.

[0027] The brake actuator units 18 each comprise an electromechanical brake actuator with an electric motor and a spindle drive.

[0028] Specifically, each brake actuator unit 18 can be controlled by its own associated control unit 20.

[0029] The individual control units 20 can in turn be connected to a higher-level central control unit 22 for signaling purposes and receive signals from this, for example a brake signal generated by a brake actuation unit.

[0030] Fig. 2 shows a microprocessor 24 contained in a control unit 20. In particular, each control unit 20 comprises a corresponding microprocessor, so that a separate microprocessor 24 is provided for each vehicle wheel 12, 13, 14, 15.

[0031] The microprocessor 24 has a first section 26 and a second section 28.

[0032] Furthermore, the microprocessor 24 includes a program memory 30.

[0033] In addition, the microprocessor 24 has a logic module 32 on which a reset logic is stored.

[0034] A first program code Prg1 for triggering a restart of the control unit 20 is stored on the first section 26 of the microprocessor 24.

[0035] Such a restart is triggered, for example, when the vehicle is started or when a software error requires a restart, for example, because a division by zero has occurred or because of electromagnetic interference. A restart of the control unit 20 when starting the vehicle 10 is triggered, in particular, by actuating the ignition. In this case, an external reset signal RS E to the microprocessor 24, more precisely to the logic module 32.

[0036] In the second section, a second program code Prg2 is stored, which, when the control unit 20 is restarted and a brake command is present, controls the brake actuator unit 18 to brake the associated vehicle wheel 12, 13, 14, 15.

[0037] The second program code Prg2 can, in the event of a restart of the control unit 20 triggered by the first program code Prg1, control the brake actuator unit 18 in the presence of a brake command to brake the associated vehicle wheel 12, 13, 14, 15.

[0038] In particular, the second program code Prg2 runs independently of the first program code Prg1 after it is initiated by the restart and the brake command.

[0039] Alternatively, it is conceivable that the second program code Prg2 is also set up to perform a restart, so that when a restart is requested, either the first program code Prg1 or the second program code Prg2 runs, depending on whether a brake command is present or not.

[0040] A method for controlling a braking process in a vehicle 10 using the microprocessor 24 is described below.

[0041] Such a method takes place in particular while the vehicle 10 is in operation, namely when the control unit 20 of the electromechanical brake 16 detects an electronic fault that requires a restart of the control unit 20.

[0042] Specifically, the restart of the control unit 20 is initiated as mentioned above by an external reset signal RS E or by an internal reset signal RS I triggered, whereby the external reset signal RS E in the control unit outside the microprocessor and the internal reset signal RS I in the microprocessor itself. With an internal reset signal RS I It is usually a software error.

[0043] The external reset signal RS E and / or the internal reset signal RS I are sent to logic module 32 to trigger a restart.

[0044] However, before a restart is triggered, the control unit 20 first checks whether a braking process is currently taking place.

[0045] This is done in particular by a status signal S ST is sent to the logic module 32 of the microprocessor 24 when a braking operation takes place.

[0046] The status signal can be an internal status signal S ST-I or an external status signal S ST-E be.

[0047] The internal status signal S ST-I is generated by the microprocessor 24 itself, for example based on a program code running in the microprocessor 24.

[0048] The external status signal S ST-E is a signal generated within the control unit 20 but outside the microprocessor 24. For example, the external status signal S ST-E on a current control of the brake actuator unit 18. In particular, the external status signal S ST-Ebased on a current consumption of the brake actuator unit 18.

[0049] If no braking operation takes place, ie if no status signal S ST is sent to the logic module 32, a restart of the control unit 20 is triggered by executing the first program code Prg1, which is stored on the first section 26 of the microprocessor 24.

[0050] This case occurs when the external and / or internal reset signal RS E , RS I present, but neither the external status signal S ST-E nor the internal status signal S ST-I present.

[0051] When a braking operation takes place, ie when an external and / or an internal reset signal RS E , RS I present and an external and / or internal status signal S ST-E , S ST-Iis sent to the logic module 32, a restart of the control unit 20 is triggered, in particular in the first section 26, and in addition a braking process is initiated and controlled by the second program code Prg2, which is stored on the second section 28 of the microprocessor 24.

[0052] If an electronic fault has occurred, an error code is stored in program memory 30.

[0053] The method described above can run independently for each vehicle wheel 12, 13, 14, 15 on a separate microprocessor 24 assigned to the vehicle wheel 12, 13, 14, 15.

Claims

[1] Electromechanical brake (16) with at least one brake actuator unit (18) assigned to a vehicle wheel (12, 13, 14, 15), and with a control unit (20) for controlling the brake actuator unit (18), wherein the control unit (20) comprises a microprocessor (24) which has a first section (26) and a second section (28), wherein a first program code (Prg1) for triggering a restart of the control unit (20) is stored in the first section (26), and a second program code (Prg2) is stored in the second section (28), which, when the control unit (20) is restarted and when a braking command is present, controls the brake actuator unit (18) to brake the assigned vehicle wheel (12, 13, 14, 15). [2] Electromechanical brake (16) according to claim 1, characterized bythat the second program code (Prg2) controls the brake actuator unit (18) in the event of a restart of the control unit (20) triggered by the first program code (Prg1) in the presence of a brake command to brake the associated vehicle wheel (12, 13, 14, 15). [3] Electromechanical brake (16) according to claim 1 or 2, characterized by that the second program code (Prg2) runs independently of the first program code (Prg1) after it has been initiated by the restart and the brake command. [4] Electromechanical brake (16) according to claim 1, characterized by that the second program code (Prg2) is also designed to trigger a restart of the control unit (20). [5] Electromechanical brake (16) according to one of the preceding claims, characterized bythat for each vehicle wheel (12, 13, 14, 15) a separate microprocessor (24) is provided, which is equipped with the first program code (Prg1) and the second program code (Prg2) on separate, assigned sections (26, 28). [6] Electromechanical brake (16) according to one of the preceding claims, characterized by that the microprocessor (24) comprises a logic module (32) on which a reset logic is stored. [7] Method for controlling a braking operation in a vehicle (10) with an electromechanical brake (16) by means of a microprocessor (24), the method comprising the following steps: - a control unit (20) of the electromechanical brake (16) detects an electronic fault, - when the fault occurs, the control unit (20) checks whether a braking operation is currently taking place, - if no braking operation takes place, a restart of the control unit (20) is triggered by executing a first program code (Prg1) stored on a first section (26) of a microprocessor (24), - when a braking operation takes place, a restart of the control unit (20) is triggered and a braking operation is initiated and controlled by a second program code (Prg2) which is stored on a second section (28) of the microprocessor (24). [8] Method according to claim 7, characterized by that when a braking operation takes place, the restart of the control unit (20) in the first section is triggered. [9] Method according to claim 7 or 8, characterized by that the first program code (Prg1) is independent of the second program code (Prg2). [10] Method according to one of claims 7 to 9, characterized by that the restart of the control unit (20) is initiated by an external reset signal (RS E) or by an internal reset signal (RS I ) is triggered, whereby the external reset signal (RS E ) in the control unit (20) outside the microprocessor (24) and the internal reset signal (RS I ) is triggered in the microprocessor (24) itself. [11] Method according to one of claims 7 to 10, characterized by that a status signal is sent to a logic module (32) of the microprocessor (24), on which a reset logic is stored, when a braking operation takes place, wherein the status signal is an internal status signal (S ST-I ) or an external status signal (S ST-E ) is. [12] Method according to one of claims 7 to 11, characterized by that when an electronic fault occurs, an error code is stored in a program memory (30). [13] Method according to one of claims 7 to 12, characterized bythat the method runs independently for each vehicle wheel (12, 13, 14, 15) on a separate microprocessor (24) assigned to the vehicle wheel (12, 13, 14, 15).

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