Control method for adjusting the position of an electromechanical parking brake - Patents.com

Abstract

The present invention relates to a control method for adjusting the position of an electromechanical parking brake. [Solution] According to this control method, the position of the parking brake actuator (20) is adjusted by drive control using an actuator control unit (2), in which a writable non-volatile memory unit (3) is provided in which position data (P) relating to the instantaneous actuator position (AP) of the actuator (20) is readably and writably stored, and according to the control method, when a write error occurs when writing the position data (P) into the memory unit (3), drive control of the actuator (20) to adjust the position of the actuator (20) is continued, and according to the control method, when a write error is detected, a synchronization process (S) is performed independently of the drive control of the actuator (20), so that after completion of the synchronization process (S), the position data (P) filed in the memory unit (3) correctly represents the actuator position (AP) of the actuator (20).

Description

[Technical field]

[0001] The present invention relates to a control method for adjusting the position of an electromechanical parking brake, as well as a system designed or programmed to implement the method. [Background technology]

[0002] In modern motor vehicles, electromechanical parking brakes are used to prevent the stopped vehicle from rolling away, especially after it has come to a stop on a roadway with a suitable roadway surface. For this purpose, a controllable electric actuator of the electromechanical parking brake can be adjusted in the course of being locked into a locked position in which a brake caliper having at least one brake pad, rigidly connected to the actuator, locks the rotational movement of the wheel by mechanically contacting a brake disc rigidly arranged on the wheel of the motor vehicle. In the course of unlocking the parking brake, the actuator is moved away from the locked position into an unlocked position in which the brake caliper is spaced from the brake disc, thereby allowing the rotational movement of the wheel.

[0003] It is known that a control system for the brake (hereinafter referred to as "brake control device") controls a microcontroller (hereinafter referred to as "actuator control unit") that is specially adapted to the respective actuator and thus to the electromechanical parking brake in order to ensure compatibility with electromechanical parking brakes of various manufacturers. In order that the actuator is controlled by the brake control device via the actuator control unit, the brake control device and the actuator control unit are communicatively connected to each other. In this way, compatibility problems between the brake system and the original electromechanical parking brake are avoided.

[0004] For correct control and positioning of the actuator, the instantaneous actuator position is usually written in the form of so-called position data into a non-volatile, writable memory unit, from which it can be read out again if necessary.

[0005] It has been found to be problematic in this case that when writing the position data to the memory unit, writing delays and thus undesirable delayed control of the actuator by the actuator control unit can often occur. Often in such cases, an error is reported by the actuator control unit to the brake control unit when the writing process to the memory unit takes too long and cannot be completed correctly, particularly within a predefined time interval. Such an error message is, in turn, usually transferred from the brake control unit to the driver of the vehicle. In order to erase such an error message again from the error memory, the driver of a vehicle having a parking brake must switch off the drive system and, in the case of a vehicle having an internal combustion engine, switch off its ignition, switch it on again and lock the position adjustment of the actuator until it is switched on, so that the parking brake cannot be particularly unlocked or locked in the meantime.

[0006] This is highly impractical for the driver of the vehicle. Summary of the Invention [Problem to be solved by the invention]

[0007] SUMMARY OF THE DISCLOSURE The object of the present invention is to provide a method for controlling an electromechanical parking brake, which takes into account the above-mentioned problems. [Means for solving the problem]

[0008] This problem is solved by the subject matter of the independent claims. Preferred embodiments are the subject matter of the dependent claims.

[0009] According to this solution, the basic idea of ​​the invention is that if a write error occurs when writing position data representing the instantaneous position of the actuator in the memory unit, the control of the actuator of the electromechanical parking brake is not interrupted, but rather the control of the actuator and thus the adjustment of the actuator's position is continued despite the error occurring when writing the latest position data of the actuator in the memory unit. According to the invention, when such a write error or a delay in the writing process occurs, it is proposed to carry out a synchronization process in the memory unit in parallel or subsequently for the control or adjustment of the actuator, so that at the latest after the end of this synchronization process it is guaranteed that the position data filed in the memory unit correctly represent the instantaneous actuator position of the actuator.

[0010] In this way, such undesirable error messages to the driver, which are caused by errors or delays in writing the position data into the memory unit, are avoided. Undesirable interruptions in the adjustment of the actuator position are also prevented. As a result, the adjustment of the actuator position is performed quickly and especially without the issuance of an error message to the driver, as requested by the driver via the brake control device. This results in improved driving safety during the adjustment and thus also during unlocking or locking of the electromechanical parking brake.

[0011] In the control method according to the invention for adjusting the position of an electromechanical parking brake, the actuator of the parking brake is adjusted by controlling it with the aid of an actuator control unit. For this purpose, a writable non-volatile memory unit is used, in which position data relating to the instantaneous actuator position of the actuator is stored readably and writably. In accordance with the method, in the event of a write error or a write delay when writing the position data in the memory unit, the control of the actuator for adjusting the position of the actuator is not interrupted but is continued. According to the invention, when a write error or a write delay is detected, a synchronization process is carried out independently of the control of the actuator, which ensures that the position data filed in the memory unit correctly represent the actuator position of the actuator.

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

[0013] According to a preferred embodiment, the method uses at least one marking parameter describing the validity of the instantaneous position data stored in the memory unit, which may have a default value and at least one marking value different from the default value. In this way, it is possible to check and inquire at any time whether the position data stored in the memory unit correctly conveys the instantaneous actuator position. This reduces the burden of correct implementation of the actuator position adjustment process and also reduces the burden of correct implementation of the synchronization process for synchronizing the position data stored in the memory unit. In particular, it is avoided to operate with incorrect position data and thus cause errors when adjusting the position of the actuator.

[0014] According to a preferred embodiment, when an error occurs during the writing process of the position data in the memory unit, the marking parameters are changed or are changed from the default values ​​to the first or second marking values. In this way, on the one hand, it is ensured that the synchronization process, which is essential to the invention, should still be carried out. On the other hand, by reading the first marking value, it is ensured that the position data momentarily filed in the memory unit should not be used until the synchronization process has been successfully completed, because due to the errors that occurred during the writing process of the position data, there is no guarantee that this position data correctly represents the momentary actuator position of the actuator.

[0015] Preferably, in the method of the invention, the writing process is evaluated as abnormal and the marking parameters are changed to the first marking values ​​at least after a preset maximum time period for performing the writing process has been exceeded.

[0016] It is also preferred that, according to the method of the invention, before the start of the writing process, the marking parameter is changed to a second marking value, so that in this way an unexpected interruption of the power supply to the actuator can be detected.

[0017] According to a preferred embodiment of the method, after the writing process is finished, the first marking parameters are changed to default values.

[0018] Since the marking parameters are set to the second marking value at the start of the writing process and are reset to the default value after the end of the writing process, the presence of the second marking value means that the writing process has been interrupted based on an interruption in the current supply at another time during the writing process, in particular when querying the marking parameters at the start of the method.

[0019] The invention further relates to a system with a controllable actuator for an electromechanical parking brake, positionable between a locked position and an unlocked position, the system having an actuator control unit for controlling the actuator, the system further having a brake control device for executing a computer program product, communicating with the actuator control unit by means of a communication connection, the system being designed or programmed for carrying out the method according to the invention, so that the advantages of the method according to the invention are transferred to the system according to the invention.

[0020] Further important features and advantages of the invention are set out in the dependent claims, the drawings and the accompanying description of the drawings.

[0021] It is self-evident that the features mentioned above and which will be explained below can be used not only in the respective given combinations, but also in other combinations or alone, without departing from the framework of the invention. [Brief description of the drawings]

[0022] [Figure 1] FIG. 1 is a diagram illustrating an example of a system according to the present invention; [Diagram 2] 2 is a flow chart illustrating a method according to the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0023] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention are illustrated in the drawings and described in detail below, where like reference numbers indicate the same or similar or functionally the same elements.

[0024] Figure 1 illustrates diagrammatically the structure of a system 1 according to the invention. The system 1 comprises an actuator control unit 2 by means of which a parking brake actuator 20, not shown in detail in Figure 1, can be adjusted between various actuator positions. In particular, the actuator 20 is adjusted between a locked position and an unlocked position, where the actuator is in principle also adjustable to any number of intermediate positions between the locked and unlocked positions. Furthermore, the system 1 comprises a writable non-volatile memory unit 3, in which position data P can be filed which describe the actuator positions AP occupied at a moment by the actuator 20.

[0025] Furthermore, the system 1 comprises a brake control device 4 in which a computer program product can be executed. Such a brake control device 4 functions in this system as a so-called "host" which provides, inter alia, the hardware required for operating the parking brake. A computer program product can be executed in the brake control device 4 by means of which the actuator 20 can be indirectly (by controlling the actuator control unit 2) actuated and thus adjusted in position.

[0026] During such control of the actuator 20, the brake controller 4 and the actuator control unit 2 can communicate with each other, exchanging data with each other, via the communication connection 5. This is done, for example, if the parking brake is locked and therefore the actuator 20 has to be adjusted from an unlocked position to a locked position. In this case, a computer program product executed in the brake controller 4 requests such an adjustment of the actuator 20 by the actuator control unit 2 via the communication connection 5.

[0027] The instantaneous actuator position AP changes continuously during the position adjustment of the actuator 20. The value of the instantaneous actuator position AP, which constantly changes during the position adjustment, is written as position data P by the actuator control unit 2 into the memory unit 3.

[0028] In conventional systems, delays in the write process may result in concomitant delays in controlling the actuation of actuator 20, since adjustment of the position of actuator 20 is dependent on writing the instantaneous actuator position AP into memory unit 3 and is not specifically performed in parallel with this write process.

[0029] As can be seen from the diagram in FIG. 2, which shows a schematic representation of a path D of the method according to the invention, in the method according to the invention the filed position data P in the memory unit 3 is synchronized independently of the position adjustment of the actuator 20, i.e. path D includes a synchronization process S for the position data P with the actual actuator position AP of the actuator 20. With the aid of such a synchronization process S, it is ensured that the filed position data P in the memory unit 3 correctly represents the actuator position AP. This is particularly true, for example, even when delays occur during the writing process or errors occur during the writing process, since the file, i.e. the memory, of the position data P in the memory unit 3 is reorganized. In other words, in the method according to the invention, the filed position data P in the memory unit 3 is updated instantaneously, while the control of the actuator 20 and thus the position adjustment are continued. In particular, if a writing error occurs when writing the position data P in the memory unit 3, the control of the actuator 20 for the position adjustment by the actuator control unit 2 is not interrupted but is continued. The synchronization of the position data P and the actuation or position adjustment of the actuator 20 are carried out in this case parallel to one another in time.

[0030] In the illustrated path D of the method, according to the exemplary scenario of Fig. 2, a marking parameter MP1 is used which, like the position data P, is readable and writable, i.e. variable, can be filed in the memory unit 3 and characterizes the validity of the latest position data P filed in the memory unit 3. For this purpose, the marking parameter MP1 may have various values, i.e. a default value F0 as well as two marking values ​​different from this default value F0 (hereinafter referred to as first and second marking values ​​F1 and F2).

[0031] If there are no write errors at all or at least no write errors are detected in the memory unit 3 and thus the last written position data P correctly represent the latest actuator position AP of the actuator 20, the marking parameter MP1 is set to the default value F0 during the method. In contrast, the first marking value F1 indicates that a timeout error has occurred during the writing process. Since the marking parameter MP1 is set to the second marking value F2 at the start of the writing process and is reset to the default value F0 after the end of the writing process, the presence of the second marking value F2 means that the writing process has been interrupted at another time during the writing process, in particular at the interrogation of the marking parameter MP1 at the start of the method, due to an interruption in the current supply.

[0032] In the following, said path D of the method according to the invention is explained in more detail with the aid of the flow chart of Fig. 2. It is self-evident that the method can be carried out in an iterative manner, for which purpose several paths D can be arranged next to each other. It is assumed, for example, that an internal combustion engine is used as the drive unit of a motor vehicle.

[0033] At the beginning of path D, it is checked according to the means M0 whether an unexpected interruption U of the current supply has occurred during the preceding ignition cycle of the internal combustion engine. If an interruption has occurred, the marking parameter MP1 is interrogated. If the interrogation shows that the marking parameter MP1 has the value F0, the stored position data P are evaluated as valid.

[0034] On the other hand, if the marking parameter MP1 is set to the first marking value F1, this means that no interruption in the current supply has occurred, but a write error as a timeout has occurred and the stored position data P is evaluated as invalid. If the marking parameter MP1 is set to the second marking value F2, this means that a current supply interruption U has occurred during the writing process of the position data P in the preceding ignition cycle.

[0035] In this case too, the position data P is evaluated as invalid.

[0036] If the pre-check by means M0 indicates that the marking parameter MP1 is set to the first or second marking value F1, F2, the method proceeds to means M6, which will be described below, i.e. means M2 to M5, which will also be described below, are skipped.

[0037] On the other hand, if the pre-check by the means M0 indicates that the marking parameter MP1 is set to the default value F0, then the marking parameter is set to the value F2, which means that the writing process is then carried out.

[0038] In a subsequent step M1, an adjustment movement of the actuator 20 is requested by the brake control device 4 via the communication connection 5 by the actuator control unit 2, for example from the unlocked position to the locked position.

[0039] In response to the measure M1, in a measure M2 which follows the measure M1, the brake control device 4 is requested by the actuator control unit 2 via the communication connection 5 to adapt the position data P stored in the memory unit 3 to the change in the actuator position AP which is obtained during the adjustment of the position of the actuator 20, which is carried out during the measure M3 of the method according to the invention which follows the measure M2.

[0040] In the course of the method, in the step M4 following the step M3, it is checked whether an error has occurred during the writing process of the changed position data P into the memory unit 3. The writing process lasts for a preset maximum time length t maxIf the marking parameter MP1 exceeds the second marking value F2, it is evaluated as being abnormal. In this case, if an error occurs during the writing process of the changed position data P into the memory unit 3, the marking parameter MP1 is changed from the second marking value F2 to the first marking value F1 during the process by the means M4. If no error occurs during the writing process, the marking parameter MP1 is changed from the second marking value F2 to the default value F0 during the process by the means M4.

[0041] The drive control of the actuator 20 continues by the actuator control unit 2 regardless of whether the writing process is evaluated as erroneous or not.

[0042] If an error is detected, the marking parameter MP1 is reset again to the default value F0 following the means M4.

[0043] In further means M5, the value of the marking parameter MP1 is queried. If this value is set to the default value F0, this means that the previously performed writing process has been successfully completed and that the stored position data P are valid, and the current pass D of the method is terminated. If, on the other hand, the marking parameter MP1 is set to the first marking value F1 or to the second marking value F2, then according to further means M6, the stored position data P is newly adapted to the instantaneous actuator position AP, and thus the position data P filed in the memory unit 3 are valid, which indicates that the instantaneous actuator position AP is correct. The marking parameter MP1 is then set to the default value F0 and the method is terminated. [Explanation of symbols]

[0044] 1 System 2 Actuator Control Unit 3 Memory Unit 4 Brake control device 5. Communication Connection 20 Actuator AP Actuator Position D-pass F0 Default value F1 First marking value F2 Second marking value M0,M1,M2,M3,M4,M5,M6 means MP1 Marking Parameters P Position data S Synchronization Process t max Maximum time length U Current supply interruption

Claims

1. 1. A control method for adjusting a position of an electromechanical parking brake, comprising: adjusting the position of the parking brake actuator (20) by drive control using an actuator control unit (2) according to the control method; a writable non-volatile memory unit (3) is provided, in which position data (P) relating to an instantaneous actuator position (AP) of the actuator (20) is readably and writably stored; Continuing to control the actuator (20) for adjusting its position when a write error occurs or when writing the position data (P) into the memory unit (3) according to the control method; A control method for adjusting the position of an electromechanical parking brake, comprising: performing a synchronization process (S) independently of drive control of the actuator (20) when a writing error is detected according to the control method, so that after completion of the synchronization process (S), the position data (P) filed in the memory unit (3) correctly represents the actuator position (AP) of the actuator (20).

2. 2. The method according to claim 1, characterized in that the synchronization process (S) is performed in parallel with the drive control of the actuator (20).

3. 3. The method according to claim 1 or 2, characterized in that at least one marking parameter (MP1) is used to characterize the validity of the momentary position data (P) filed in the memory unit (3), the marking parameter (MP1) having a default value (F0) and at least one marking value (F1, F2) different from the default value (F0).

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

5. 5. The method according to claim 4, characterized in that, if a preset maximum time length (tmax) for performing the writing process is exceeded, the writing process is evaluated as abnormal and the marking parameter (MP1) is changed to the first marking value (F1).

6. 6. The method according to claim 4 or 5, characterized in that before the start of the writing process, the marking parameter (MP1) is changed to the second marking value (F2), so that in this way an unexpected interruption (U) of the power supply to the actuator (20) can be detected.

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

8. 8. The method according to claim 3, further comprising checking the presence or absence of valid position data (P) in the memory unit (3) at the start of the method by querying the marking parameters (MP1), and, if no valid position data (P) is present, the stored position data (P) is (re)adapted to the instantaneous actuator position (AP).

9. In the system (1), A controllable actuator (20) for an electromechanical parking brake, the actuator being positionably adjustable between a locked position and an unlocked position, an actuator control unit (2) for controlling the actuator (20); a brake control device (4) for executing a computer program product, in communication with said actuator control unit (2) by means of a communication connection (5), The system (1) is designed / programmed to carry out the method according to any one of claims 1 to 8. System (1).

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