Control method for adjusting an electromechanical parking brake

Abstract

The invention relates to a control method for adjusting an electromechanical parking brake, - according to which method the actuator (20) of the parking brake is adjusted by means of actuation by an actuator control unit (2), - wherein a non-volatile writable memory unit (3) is provided, in which memory unit (3) position data (P) relating to the instantaneous actuator position (AP) of the actuator (20) are stored in a readable and writable manner; - according to which method, in the event of a write error when writing position data (P) into the memory unit (3), the actuation of the actuator (20) is continued in order to adjust the actuator (20); - according to which method, upon recognition of the write error, a synchronization process (S) is carried out independently of the actuation of the actuator (20), such that after the synchronization process (S) is concluded, the position data (P) stored in the memory unit (3) correctly reproduce the actuator position (AP) of the actuator (20).

Description

TECHNICAL FIELD

[0001] The invention relates to a control method for adjusting an electromechanical parking brake, and to a system which is set up or programmed to carry out the method. BACKGROUND

[0002] In modern motor vehicles, electromechanical parking brakes are employed in order to make it impossible for a parked vehicle to roll away, in particular after parking on a lane having a sloping lane surface. For this purpose, a controllable electric actuator of the electromechanical parking brake can be adjusted to a locking position in the course of a locking process, in which locking position a brake caliper which is fixedly connected to the actuator, which brake caliper comprises at least one brake friction lining, prevents a rotational movement of a wheel of the motor vehicle by mechanical contact with a brake disc which is fixedly arranged at the wheel. In the course of an unlocking process of the parking brake, the actuator can be moved from the locking position to an unlocking position, in which the brake caliper is arranged spaced apart from the brake disc and thus releases the rotational movement of the wheel.

[0003] In order to ensure compatibility of a control system for the brake, hereinafter referred to as "brake control device", with electromechanical parking brakes of different manufacturers, it is known to operate the adjustable actuator by means of a microcontroller, hereinafter referred to as "actuator control unit", which is specifically adapted to the respective actuator and thus to the electromechanical parking brake. In order to control the actuator by means of the brake control device via the actuator control unit, the brake control device and the actuator control unit are in communication connection with one another. Compatibility problems between the brake system and the actual electromechanical parking brake are thus avoided.

[0004] In order to correctly operate and adjust the actuator, the instantaneous actuator position is usually written in the form of so-called position data to a non-volatile writable memory unit and there read again at any time if necessary.

[0005] However, it is often proven problematic in this case that a write delay can occur when writing the position data into the storage unit and, in connection therewith, an undesired delayed actuation of the actuator by the actuator control unit can also occur. In this case, the actuator control unit often reports an error to the brake control device if the write process into the storage unit has lasted too long and, in particular, has not been possible to successfully end within a predefined time interval. As a rule, this error report is in turn forwarded by the brake control device to the driver of the motor vehicle. In order to delete this error report from the error memory again, it can be necessary for the driver of the motor vehicle with the parking brake to switch off the drive system (in the case of a motor vehicle with an internal combustion engine, the ignition of the internal combustion engine) and to switch it on again and to prevent the actuation of the actuator until then, so that, in particular, the parking brake cannot be unlocked or locked during this time.

[0006] This proves to be extremely impractical for the driver of the motor vehicle. SUMMARY

[0007] It is therefore the task of the present application to provide a method for actuating an electromechanical parking brake which takes the above-mentioned difficulties into account.

[0008] This task is solved by the solution according to the present application. According to a control method for actuating an electromechanical parking brake, the actuator of the parking brake is actuated by means of an actuator control unit, wherein a non-volatile writable storage unit is provided in which position data relating to the instantaneous actuator position of the actuator are stored in a readable and writable manner; in the event of a write error, or when writing the position data into the storage unit, the actuation of the actuator for actuating the actuator is continued; upon recognition of the write error, a synchronization process is carried out independently of the actuation of the actuator, so that after the synchronization process has ended, the position data stored in the storage unit correctly reproduce the instantaneous actuator position of the actuator.

[0009] The basic idea of the present application is therefore that, if a write error occurs when writing the position data reproducing the instantaneous position of the actuator into the storage unit, the actuation of the actuator of the electromechanical parking brake is not interrupted, but, on the contrary, the actuation of the actuator and thus the actuation of the actuator is continued despite the error when writing the current position data of the actuator into the storage unit. According to the present application, it is proposed that, in the event of such a write error or delay in the write process, a synchronization process is carried out in the storage unit in parallel with the actuation or actuation of the actuator or subsequently, so that it is ensured at the latest after the end of the synchronization process that the position data stored in the storage unit correctly reproduce the instantaneous actuator position of the actuator.

[0010] In this way, the above-mentioned, undesired error messages to the driver, which are triggered due to an error in writing the position data into the storage unit or due to a delay in writing the position data into the storage unit, are avoided. Likewise, undesired interruptions of the adjustment of the actuator are prevented. As a result, therefore, the adjustment of the actuator can be carried out quickly and, in particular, without generating error messages to the driver, as required by the driver via the brake control device. This leads to an improved operational safety when adjusting the electromechanical parking brake and, thus, also when unlocking or locking the electromechanical parking brake.

[0011] In the control method for adjusting an electromechanical parking brake according to the application, the actuator of the parking brake is adjusted by means of a manipulation by the actuator control unit. For this purpose, a non-volatile, writable storage unit is used, in which position data relating to the instantaneous actuator position of the actuator are stored in a readable and writable manner. According to the method, in the event of a write error or a write delay in writing the position data into the storage unit, the manipulation of the actuator is not interrupted, but continued, in order to adjust the actuator. According to the application, upon recognition of the write error or the write delay, a synchronization process is carried out independently of the manipulation of the actuator, by means of which it is ensured that the position data stored in the storage unit correctly reproduces the actuator position of the actuator.

[0012] According to one preferred embodiment, the synchronization process is carried out in time parallel to the manipulation or adjustment of the actuator. In this way, the adjustment process of the actuator is not interrupted, so that the vehicle can be quickly unlocked or locked with the electric parking brake. In particular, undesired delays in unlocking or locking the parking brake are prevented.

[0013] According to one advantageous extension, the method uses at least one marker parameter describing the validity of the position data temporarily stored in the storage unit, which can take a default value and at least one marker value deviating therefrom. In this way, it can always be determined and checked whether the position data stored in the storage unit correctly reproduces the instantaneous actuator position. This makes it easy to correctly carry out the adjustment process of the actuator and also the synchronization process for synchronizing the position data stored in the storage unit. In particular, it is avoided that incorrect position data is worked with, which can lead to errors in adjusting the actuator.

[0014] According to an advantageous development, the flag parameter is changed from the default value to the first or second flag value if an error occurs in the course of writing the position data into the storage unit. In this way, on the one hand, it can be identified that the erfindungswesentliche synchronization process is still to be carried out. On the other hand, by reading the first flag value, it can be identified that the position data temporarily stored in the storage unit are not to be used until the synchronization process has successfully ended, since due to the error occurring in the course of writing the position data, it is not ensured that these position data correctly reproduce the instantaneous actuator position of the actuator.

[0015] Advantageously, in the method according to the application, if a predetermined maximum duration for carrying out the writing process has been exceeded, then the writing process is at least classified as erroneous and the flag parameter is changed to the first flag value.

[0016] Likewise advantageously, in the method according to the application, the flag parameter is changed to the second flag value before the writing process is started, so that in this way it can be identified that an unexpected interruption of the power supply to the actuator has occurred.

[0017] According to an advantageous development of the method, after the writing process has ended, the first flag parameter is changed to the default value.

[0018] Since the flag parameter is set to the second flag value at the start of the writing process and is reset to the default value after the writing process has ended, in the case of an inquiry into the flag parameter at a point in time other than during the writing process, in particular at the start of the method, the second flag value means that the writing process has been interrupted due to an interruption of the power supply.

[0019] Furthermore, the application also relates to a system having a controllable actuator for an electromechanical parking brake, which controllable actuator can be adjusted between a locked position and an unlocked position. The system comprises an actuator control unit for controlling the actuator. Furthermore, the system comprises a brake control device for implementing the computer program product, which brake control device communicates with the actuator control unit by means of a communication connection. The system is set up or programmed to carry out the above-explained method according to the application, so that the above-mentioned advantages of the method according to the application are transferred to the system according to the application.

[0020] Further important features and advantages of the application result from the disclosure of the application, from the figures and from the related figure description according to the figures.

[0021] It is readily understood that the features mentioned above and still to be explained below can be used not only in the respectively stated combination, but also in other combinations or alone, without departing from the scope of the application. Attached Figure Description

[0022] Preferred embodiments of the invention are shown in the accompanying drawings and will be described in more detail in the following description, wherein the same reference numerals refer to the same or similar or functionally identical components.

[0023] Indicatively:

[0024] Figure 1 The structure of the system according to the present invention is illustrated by way of example;

[0025] Figure 2 A flowchart illustrating the method according to the present invention is shown. Detailed Implementation

[0026] Figure 1 A schematic diagram illustrates the structure of system 1 according to the present invention. System 1 includes an actuator control unit 2, by means of which, in... Figure 1 The actuator 20 of the parking brake, not shown in more detail, can be adjusted between different actuator positions. In particular, the actuator 20 can be adjusted between a locked position and an unlocked position, and in principle, the actuator can also be adjusted to any number of intermediate positions between the locked and unlocked positions. Furthermore, the system 1 includes a non-volatile writable memory unit 3. In the memory unit 3, position data P can be stored, which describes the actuator position AP temporarily occupied by the actuator 20.

[0027] Furthermore, the system 1 also includes a brake control device 4 in which a computer program product can be implemented. In this system, the brake control device 4 can act as a so-called "host," which also provides the hardware required to operate the parking brake. The computer program product implemented in the brake control device 4 allows the actuator 20 to be indirectly (through the control of the actuator control unit 2) and to be regulated in this manner.

[0028] During this operation of actuator 20, brake control device 4 and actuator control unit 2 can communicate with each other by exchanging data via communication link 5. This occurs, for example, when the parking brake needs to be locked and actuator 20 needs to be adjusted from the unlocked position to the locked position for this purpose. In this case, the computer program implemented in brake control device 4, via communication link 5, requests actuator control unit 2 to make this adjustment to actuator 20.

[0029] During the adjustment of actuator 20, the instantaneous actuator position AP changes continuously. The value of the constantly changing instantaneous actuator position AP during this adjustment period is written as position data P by actuator control unit 2 into storage unit 3.

[0030] In a conventional system, delays may occur during the write process, and consequently, delayed manipulation of the actuator 20 may occur because the adjustment of the actuator 20 is not performed independently of writing the instantaneous actuator position AP to the memory cell 3, and especially not in parallel with the write process in time.

[0031] like Figure 2 As illustrated in the diagram (which schematically illustrates the process D of the method according to the invention), in the method according to the invention, the position data P stored in the storage unit 3 is synchronized independently of the adjustment of the actuator 20; that is, the process D includes a synchronization process S for the position data P with the actual actuator position AP of the actuator 20. This synchronization process S ensures that the position data P stored in the storage unit 3 correctly reproduces the actuator position AP. This applies even if a delay or error occurs during the write process (for example, because the position data P is stored in the storage unit 3, i.e., the storage is reorganized), or especially when a delay or error occurs during the write process (for example, because the position data P is stored in the storage unit 3, i.e., the storage is reorganized). In the method according to the invention, the position data P temporarily stored in the storage unit 3 is thus updated, and the operation and therefore adjustment of the actuator 20 continue. In particular, in the event of a write error when writing position data P to storage unit 3, the actuator 20 is not interrupted, but rather controlled and adjusted via actuator control unit 2. Here, the synchronization of position data P and the control or adjustment of actuator 20 can be performed in parallel with each other in time.

[0032] In process D shown in this method, according to Figure 2 In the example scenario, using the tag parameter MP1, similar to the location data P, the tag parameter MP1 can be stored in storage unit 3 in a readable and writable manner (i.e., in a variable manner), and the tag parameter MP1 represents the validity of the location data P currently stored in storage unit 3. For this purpose, the tag parameter MP1 can have different values, more specifically, it can have a default value F0 and two tag values ​​deviating from the default value F0 (hereinafter referred to as the first tag value F1 and the second tag value F2).

[0033] The marking parameter MP1 is set to the default value F0 in the course of the method for the case that no write error at all exists, or at least no write error into the memory cell 3 has been recognized, and thus the finally written position data P correctly reproduce the current actuator position AP of the actuator 20. In contrast thereto, the first marking value F1 reflects that a Time-Out error occurred during the writing process. Since the marking parameter MP1 is set to the second marking value F2 at the beginning of the writing process and is reset to the default value F0 after the writing process is terminated, the presence of the second marking value F2 at a point in time other than during the writing process, in particular at the beginning of the method, means that the writing process has been interrupted due to an interruption of the power supply.

[0034] Now, the mentioned process D of the method according to the application is explained in more detail in the following according to the flow chart Figure 2 It is readily understood that the method can be performed iteratively, for which a plurality of processes D can be arranged one after the other. It is exemplarily assumed that the internal combustion engine is used as a drive device of a motor vehicle.

[0035] At the beginning of the process D, it is checked according to the measure M0 whether an unexpected interruption U of the power supply occurred during the preceding ignition cycle of the internal combustion engine. If this is the case, the marking parameter MP1 is queried. If this query results in that the marking parameter has the value F0, the stored position data P are attributed to be valid.

[0036] If, however, the marking parameter MP1 is set to the first marking value F1, this means that a write error in the form of a Time-Out occurred although no interruption of the power supply took place, and the stored position data P are attributed to be invalid. If the marking parameter MP1 is set to the second marking value F2, this means that an interruption U of the power supply occurred during the writing process of the position data P in the preceding ignition cycle.

[0037] In this case, the position data P are also attributed to be invalid.

[0038] If the check according to the measure M0 previously resulted in that the marking parameter MP1 is set to the first or second marking value F1, F2, the method is continued with the still to be explained measure M6, that is to say, the still to be explained measures M2 to M5 are skipped.

[0039] If, however, the check according to the measure M0 previously resulted in that the marking parameter MP1 is set to the default value F0, the marking parameter is set to the value F2, which means that the writing process will be carried out later.

[0040] In a following measure Ml, the actuator control unit 2 is requested by the brake control device 4 via the communication connection 5 to perform an adjustment movement of the actuator 20, for example from an unlocked position to a locked position.

[0041] In response to the measure Ml, in a measure M2 following the measure Ml, the actuator control unit 2 requests the brake control device 4 via the communication connection 5 to adapt the position data P stored in the storage unit 3 in accordance with the change in the actuator position AP resulting from the adjustment of the actuator 20, which is performed in a measure M3 following the measure M2 of the method according to the application.

[0042] In a measure M4 following the measure M3 of the method, it is checked whether an error occurred in the writing process of the changed position data P into the storage unit 3. Here, if a predetermined maximum duration t max for performing the writing process has been exceeded, the writing process is classified as erroneous. If this is the case, the flag parameter MP1 is changed from the second flag value F2 to the first flag value Fl in the course of the measure M4, if an error occurred in the writing process of the changed position data P into the storage unit 3. If no error occurred in the writing process, the flag parameter MP1 is changed from the second flag value F2 to the default value F0 in the course of the measure M4.

[0043] Irrespective of whether the writing process was classified as erroneous or not, the actuator 20 is continued to be operated by the actuator control unit 2.

[0044] If no error was identified, the flag parameter MP1 is reset to the default value F0 again immediately after the measure M4.

[0045] In a further measure M5, the value of the flag parameter MP1 is queried. If it is derived that the flag parameter is set to the default value F0 (which means that the preceding performed writing process can have ended successfully and the stored position data P is valid), the current process D of the method ends. If, however, the flag parameter MP1 is set to the first flag value Fl or to the second flag value F2, the stored position data P is adapted to the instantaneous actuator position AP in accordance with a further measure M6, so that the position data P stored in the storage unit 3 is valid thereafter and correctly reproduces the instantaneous actuator position AP. Immediately thereafter, the flag parameter MP1 is set to the default value F0 and the method ends.

Claims

1. A control method for adjusting an electromechanical parking brake, - according to which, by means of actuator control unit (2), an actuator (20) of the parking brake is adjusted, - wherein a non-volatile writable memory unit (3) is provided, in which a position data (P) relating to an instantaneous actuator position (AP) of the actuator (20) is stored in a readable and writable manner; - according to which, in the event of a write error, or when writing the position data (P) into the memory unit (3), the actuator (20) is continued to be manipulated in order to adjust the actuator (20); - according to which, upon recognition of the write error, a synchronization process (S) is carried out independently of the manipulation of the actuator (20), such that after the synchronization process (S) is concluded, the position data (P) stored in the memory unit (3) correctly reproduces the instantaneous actuator position (AP) of the actuator (20).

2. The method according to claim 1, characterized in that the synchronization process (S) is carried out in parallel in time with the manipulation of the actuator (20).

3. The method according to claim 1, characterized in that the method uses at least one marker parameter (MP1) which characterizes the validity of the position data (P) temporarily stored in the memory unit (3), the marker parameter (MP1) being able to take a default value (F0) and at least one marker value (F1, F2) deviating therefrom.

4. The method according to claim 3, characterized in that if an error occurs in the write process of the position data (P) into the memory unit (3), the marker parameter (MP1) is changed from the default value (F0) to a first marker value (F1) or a second marker value (F2).

5. The method according to claim 4, characterized in that If a predetermined maximum duration (t max ) for performing the write process has been exceeded, the write process is classified as erroneous and the marker parameter (MP1) is changed to the first marker value (F1).

6. The method according to claim 4 or 5, characterized in that before the start of the write process, the marker parameter (MP1) is changed to the second marker value (F2), such that an unintended interruption (U) of the power supply to the actuator (20) can be recognized in this way.

7. The method according to claim 6, characterized in that after the end of the write process, the marker parameter (MP1) is changed to the default value (F0).

8. The method according to any one of the preceding claims 3 to 5, characterized in that at the start of the method, it is checked by querying the marker parameter (MP1) whether valid position data (P) are present in the memory unit (3), and if no valid position data (P) are present, the stored position data (P) are adapted to the instantaneous actuator position (AP).

9. A system (1) for adjusting an electromechanical parking brake, - having a controllable actuator (20) for an electromechanical parking brake, which actuator (2) can be adjusted between a locked position and an unlocked position; - having an actuator control unit (2) for controlling the actuator (20); - having a brake control device (4) for implementing a computer program product, the brake control device (4) communicating with the actuator control unit (2) by means of a communication connection (5), - wherein the system (1) is set up / programmed to perform the method according to any one of the above claims 1-8.

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