Method for controlling an electric parking brake and / or an electric parking lock of a vehicle, in particular a motor vehicle

Abstract

Method for controlling an electric parking brake and / or an electric parking lock of a vehicle, in particular a motor vehicle, wherein the parking brake and the parking lock are electrically controlled and / or electrically operated for the respective engagement and / or disengagement, wherein an electrical vehicle electrical system for providing electrical energy, in particular a 12V low-voltage network, is provided and / or available for the respective control of the parking brake and / or the parking lock, wherein the voltage level of the electrical vehicle electrical system is monitored, in particular continuously, wherein a first critical voltage state (I) is reached when a first specific voltage level is undershot, and wherein a rolling protection of the vehicle is achieved by a corresponding first specific control of the parking brake and / or the parking lock.when the first critical voltage state (I) of the vehicle electrical system is determined and / or detected, characterized in that a second critical voltage state (II) of the vehicle electrical system, which differs from the first critical voltage state (I), can be determined and / or detected when a second specific voltage level is undershot, wherein the second specific voltage level is lower than the first specific voltage level, and that the vehicle's roll-prevention is then implemented by a corresponding second specific control of the parking brake and / or the parking lock, which differs from the first specific control, when the second critical voltage state (II) is determined and / or detected.

Description

[0001] The invention relates to a method for controlling an electric parking brake and / or an electric parking lock of a vehicle, in particular a motor vehicle, according to the features of the preamble of claim 1.

[0002] Numerous methods and / or control systems for controlling a vehicle's parking brake and / or parking lock are already known in the prior art. For example, an electric parking brake in a motor vehicle is engaged or activated when the driver presses the so-called "EPB" button. If the driver wishes to deactivate the electric parking brake, they can again press the "EPB" button. The systems known in the prior art are designed such that, in the event of a fault in the vehicle's electrical system, the electric parking brake remains in its current position. In other words, if the vehicle's electrical system fails and the electric parking brake was previously engaged, the electric parking brake remains in the engaged, i.e., activated, state.Conversely, if the vehicle's electrical system fails and the electric parking brake was not engaged beforehand, it will not engage and will remain in its released, i.e., deactivated, state. Such a system, where the relevant components remain in exactly the same position / orientation they were in before the electrical system failure, is also known as a "bistable system."

[0003] Furthermore, electric parking locks are also known in the prior art. These are engaged in a vehicle, particularly a motor vehicle, when the driver selects the drive position "P," especially via the gear selector. The drive position "P" is also referred to as the "parking position." With an electric parking lock, the electric parking lock is activated in the transmission control system, for example, when the driver presses a corresponding button and / or a gear selector and selects the drive / parking position "P," and is then essentially engaged mechanically. For this purpose, an electric motor is electrically controlled. If the vehicle's electrical system fails, such electrically engaged parking locks can also be unlocked manually, i.e., manually, by means of an "emergency release system." The currently known systems, or rather...Currently known operating modes of an electric parking lock are essentially designed to be "monostable." This means, in particular, that if the vehicle's electrical system fails, the electric parking lock will always move into the engaged position ("towards P"). In the event of a power failure, an electric holding magnet, which otherwise keeps the electric parking lock in its engaged position, can no longer be operated. Therefore, a mechanical "spring emergency system" is used to ensure that, in the event of a power failure, the electric parking lock is always moved into the engaged position. In other words, if the electrical system fails, the electric parking lock will generally always move into the engaged position, primarily to prevent the vehicle from rolling away.

[0004] Methods and / or control systems are already known in the prior art, for example from DE 10 2017 211 398 A1, from which the invention is based, in which the vehicle has an electric parking brake and an electric parking lock that are controlled accordingly. In this case, the parking brake and the parking lock are electrically controlled and / or electrically operated for their respective engagement and disengagement, in particular with the aid of corresponding electric motors / drive motors and / or controllable actuators. To implement the respective control of the parking brake and / or the parking lock, an electrical system for the vehicle's electrical power supply, in particular a 12V low-voltage network, is provided and / or present. The voltage level of the electrical system is continuously monitored. A critical voltage state is reached when a certain voltage level is undershot.In this case, vehicle roll prevention is achieved by specifically controlling the parking brake and / or parking lock, i.e., when this critical voltage state in the vehicle electrical system has been detected. If a critical voltage state in the vehicle electrical system is detected during an autonomous parking maneuver, a corresponding signal is sent to a control unit. Upon receiving the signal, the control unit will activate the braking system and / or secure the vehicle via the powertrain. In other words, during an autonomous parking maneuver, a hydraulic service brake, an electric parking brake, or an electric parking lock will be applied and / or effectively engaged in a critical voltage state to prevent the vehicle from rolling, particularly before the vehicle electrical system fails completely.

[0005] The problem of an electrical system failing and / or experiencing a critical voltage state is also described, for example, in DE 10 2018 215 605 A1. In this case, the electrical system of a motor vehicle has a first and a second circuit, with the operating voltage in the first circuit being higher than the operating voltage in the second. In addition to a main battery, the second circuit also has an auxiliary battery, thus providing a degree of system redundancy. However, the control effort for the two circuits and the implementation of this redundancy are complex and costly.

[0006] In the prior art method or system from which the invention is based, the voltage state of the vehicle's electrical system is monitored and a critical voltage state is detected. However, when this critical voltage state is detected—namely, during an autonomous parking maneuver of the vehicle—the parking brake and / or the parking lock are specifically activated to implement roll-prevention. This occurs precisely when the autonomous parking maneuver of the vehicle is underway, at which point the maneuver is aborted by the roll-prevention mechanism to secure the vehicle accordingly. For this purpose, the parking assistance system includes a monitoring unit, which is also configured to continuously or cyclically monitor the vehicle's electrical system. In any case, in the prior art method or system...On the one hand, the system does not offer a way to implement roll-away protection for other driving states of the vehicle outside of autonomous parking. On the other hand, the electric parking brake and / or the electric parking lock are simply engaged or effectively activated when the critical voltage state of the electrical system is detected. Therefore, the aforementioned method or system is not yet optimally designed.

[0007] The invention is therefore based on the objective of designing and further developing previously known methods or control systems in such a way that the flexibility of use for controlling an electric parking brake and / or an electric parking lock of a vehicle is increased, in particular by enabling simple control of the components and making this control cost-effective.

[0008] The problem previously identified is now initially solved by the features of claim 1.

[0009] The basic principle of the invention is that a second critical voltage state of the vehicle electrical system – distinct from the first critical voltage state – can be determined and / or detected when a second specific voltage level is undershot, wherein the second specific voltage level is lower than the first specific voltage level. This achieves a first advantage, namely, that, in contrast to the prior art, a distinction is made between several critical voltage states of the vehicle electrical system, or at least between a first critical and a second critical voltage state.This has the further advantage that the vehicle's roll-prevention is then achieved through a corresponding second specific activation of the parking brake and / or parking lock – different from the first specific activation – the latter occurring when the second critical voltage state is determined and / or detected. Put another way, when the first critical voltage state is determined, a first specific activation of the parking brake and / or parking lock is implemented, whereas when the second critical voltage state is determined or present, a different, second specific activation of the parking brake and / or parking lock is implemented, distinct from the first specific activation.This increases the operational flexibility of the entire system; in particular, the procedure can be applied to different driving conditions and / or different controls for the parking brake and / or the parking lock can be implemented in the different driving conditions, which will now be explained in more detail below.

[0010] In the method according to the invention, the parking brake and / or the parking lock is designed and / or configured, in particular, as a purely electrically operated parking brake and / or parking lock. In other words, the method or system according to the invention does not provide a mechanical "spring emergency system" for engaging the parking lock in the transmission when a critical voltage state of the electrical system is detected. According to the method according to the invention, which will be explained in more detail below, the electric parking brake and / or the electric parking lock is engaged under specific conditions, namely according to the first specific control or according to the second specific control in the first or second critical voltage state, respectively. The method or system according to the invention...The system according to the invention is therefore implemented in particular with purely electrically operated components, especially the purely electrically operated parking brake and the purely electrically operated parking lock of the vehicle, without the need for further mechanical "emergency assistance systems". The latter leads to a cost reduction or a cost-effective implementation of the method and / or the system according to the invention, since the method according to the invention can be implemented with the components already present in the vehicle and no costly additional components are required.

[0011] In the first critical voltage state and / or the second critical voltage state, a warning message is generally generated for the vehicle's driver and / or issued, in particular visually and / or audibly. In the first critical voltage state, the warning message "Please drive carefully" and / or "Please visit a workshop" is displayed to the driver, primarily visually. In the second critical voltage state, the warning message "Stop vehicle" is generated and / or issued, specifically to make the driver aware that they should bring the vehicle to a stop as quickly as possible.

[0012] First, the initial specific activation of the parking brake and / or parking lock can now be described once the first critical voltage state of the electrical system has been determined: The vehicle's movement, particularly its current speed, is continuously monitored and / or determined. At least during the first critical voltage state, vehicle movement is monitored, and if the vehicle is detected as stationary, the control system requests the parking brake to be applied, specifically, the parking brake is automatically applied. This serves to implement the roll-prevention mechanism during the first critical voltage state.

[0013] However, if, in the first critical stress state, the parking brake fails to engage, or engages incompletely and / or with insufficient braking force, particularly due to a malfunction, the parking lock in the vehicle's transmission is additionally engaged when the vehicle is stationary. This latter action, the engagement of the parking lock, then provides the anti-roll protection if the parking brake is inoperable for the aforementioned reasons.

[0014] In the first critical voltage state, the parking brake can be released manually by pressing an EBP button, particularly if the driver operates the EPB button. Alternatively, the parking brake will release automatically when the vehicle starts moving, especially if the driver presses the accelerator pedal, and / or a gear other than Park ("P") is engaged or selected by the driver. This means that, in the first critical voltage state, the driver essentially decides whether to disengage the parking brake and continue driving (or not), particularly when they press the accelerator pedal or select a gear other than Park ("P").

[0015] In the first critical voltage state, the aforementioned procedure or the aforementioned procedure steps begin again from the beginning when the vehicle has started moving again after coming to a standstill and has exceeded a certain speed threshold, in particular a certain minimum speed, and / or a certain period of time has elapsed.

[0016] If the first critical voltage state exists and the vehicle is moving, i.e., the vehicle is not stationary, no interventions will occur by the parking brake or the parking lock.

[0017] The following section describes in particular the second specific control of the parking brake and / or the parking lock when the second critical voltage state is present: Since the vehicle's movement and / or speed are specifically determined and / or monitored, vehicle movement is also monitored in the second critical stress state. If the vehicle is detected as stationary, the control unit requests the parking brake to be engaged, and in particular, the parking brake is automatically engaged. This process step is essentially identical to the corresponding process step in the first critical stress state. However, in the second critical stress state, the parking lock in the vehicle's transmission is also engaged, specifically the parking gear ("P") is activated. Thus, in the second critical stress state, the vehicle is always prevented from rolling via the parking lock, regardless of whether the parking brake is actually available.

[0018] The parking brake can be released manually by pressing the EPB button and / or it can be released automatically when the vehicle starts moving again, particularly when the driver presses the accelerator pedal. However, for this to occur, a gear other than parking ("P") must be engaged or actively selected by the driver during the second critical voltage state, for example, forward ("D"). This then signals the control unit to re-engage the parking brake. The aforementioned procedures apply particularly when the vehicle is stationary during the second critical voltage state.

[0019] If the second critical voltage state of the vehicle exists, but vehicle movement is detected—specifically, a vehicle speed is determined indicating that the vehicle is not stationary—for example, if the second critical voltage state is reached when the vehicle is on a country road or highway, then a torque limitation is implemented by appropriately controlling the vehicle's drive motor and / or transmission. In particular, the vehicle's maximum achievable speed is thereby limited and / or reduced. Simultaneously, a warning message is generated and / or displayed to the driver, indicating at least that the vehicle's speed is being limited and / or that an acute vehicle malfunction has occurred.In other words, the driver is specifically advised to stop and / or park the vehicle as quickly as possible. If the driver fails to do so, the parking lock in the transmission will be engaged automatically and immediately after a certain period, specifically after 60 seconds. However, this "automatic engagement" of the parking lock does not automatically mean that the parking lock is actually engaged. The actual engagement of the parking lock in the transmission only occurs when the vehicle's speed has decreased below a certain threshold, specifically 2.5 km / h.This ensures that at high vehicle speeds, especially above 2.5 km / h, the signals for the control-related engagement of the parking lock have been generated via the control system, but the parking lock is mechanically designed and constructed within the gearbox in such a way that it is only effectively engaged, and can only lock into place, at vehicle speeds below a certain limit, especially 2.5 km / h.

[0020] In the state of the vehicle where the parking lock is unconditionally engaged, the power transmission between the gearbox and the drive motor is also disconnected, and a specific warning message is generated and / or issued to the driver, in particular visually and / or audibly, whereby the warning message specifically includes the instruction to the driver that the gearbox has a defect and / or that the vehicle should be stopped as soon as possible.

[0021] Only when the vehicle has started moving again after coming to a standstill and has exceeded a certain speed threshold and / or a certain period of time has elapsed, does the control process start again from the beginning.

[0022] The advantages mentioned at the outset are achieved through the previously described process steps and the respective specific controls of the parking brake and / or the parking lock when a first or second critical voltage state is present. In particular, different control options for the electric parking brake and / or the electric parking lock can now be implemented for various vehicle driving conditions, increasing the operational flexibility of the process while simultaneously ensuring safety aspects, especially without the need for additional mechanical components. This also offers corresponding cost advantages.

[0023] There are now numerous possibilities for advantageously elaborating and further developing the method according to the invention. For this purpose, reference may first be made to the claims subordinate to claim 1. In the following, a preferred embodiment of the invention will be explained in more detail with reference to the drawing and the accompanying description. The drawing shows: Fig. 1 in schematic representation a flow chart of the individual process steps of the inventive method for controlling an electric parking brake and / or an electric parking lock of a vehicle, in particular for a determined first critical voltage state or for a second critical voltage state of the vehicle electrical system.

[0024] In the Fig. Figure 1 now schematically illustrates the essential process steps of the inventive method for controlling an electric parking brake and / or an electric parking lock of a vehicle, in particular a motor vehicle.

[0025] In particular, the method according to the invention allows for the control of the electric parking brake and / or the electric parking lock exclusively by electrical means. In other words, the electric parking brake and / or the electric parking lock are controlled or electrically operated by corresponding electric motors / drive motors and / or actuators for engaging and disengaging them. The term "engaging" refers to the activation of the parking brake and / or the parking lock. The term "disengaging" refers to the deactivation of the parking brake and / or the parking lock.

[0026] To control the parking brake and / or parking lock, an electrical system is provided and / or present to supply electrical power. This electrical system is specifically designed as a 12V low-voltage system.

[0027] The voltage level of the vehicle's electrical system is monitored, particularly continuously. This method is implemented using an electrical and / or electronic control unit, or a corresponding control device, especially a microcomputer. A separate monitoring unit may also be used to monitor the voltage level of the vehicle's electrical system.

[0028] A first critical voltage state in the vehicle's electrical system is reached when a specific voltage level is undershot, for example, when only 10V or less is present in a 12V low-voltage system. If this first critical voltage state is reached, the vehicle can be prevented from rolling by a corresponding initial activation of the parking brake and / or the parking lock. This occurs when the first critical voltage state in the vehicle's electrical system is determined and / or detected, particularly by the aforementioned monitoring unit.

[0029] The aforementioned disadvantages are now avoided by the fact that a second critical voltage state of the vehicle electrical system – different from the first critical voltage state – can be determined and / or detected when a second specific voltage level is undershot, whereby the second specific voltage level is lower than the first specific voltage level, and that the vehicle's rolling protection is then implemented by a corresponding second specific control of the parking brake and / or parking lock – different from the first specific control – when the second critical voltage state is determined and / or detected.

[0030] This has the initial advantage of allowing multiple critical voltage states of the vehicle's electrical system to be detected and / or determined. For example, a first critical voltage state occurs when the current voltage of the electrical system falls below 10V, and a second critical voltage state occurs when the current voltage of the electrical system falls below 8V. Both cases indicate an impending failure of the electrical system in the near or medium term.

[0031] For the respective different voltage states, i.e., for the first and for the second critical voltage state, the electrically operated electric parking brake and / or electric parking lock, in particular exclusively, are controlled in different ways or with different sequential sequences of process steps.

[0032] In principle, the first critical voltage state (I) and the second critical voltage state (II) are generated and / or displayed via a warning message for the vehicle's driver. This warning message can be visual and / or audible. Specifically, the first critical voltage state (I) includes the warning message "Please drive carefully" and / or "Please visit a workshop," while the second critical voltage state (II) generates and / or displays the warning message "Stop vehicle."

[0033] In the Fig. These warning messages are represented by procedure steps 1a and 1b. Simply put, in the first critical voltage state I, more extensive operation of the vehicle is still possible than in the second critical voltage state II. In particular, when the second critical voltage state II is present or detected, further safety aspects must be considered, so that the procedure steps for controlling the electric parking brake and the electric parking lock then also take place in a second – different – ​​specific way, which will be explained in more detail below.

[0034] In the Fig. Figure 1 on the left schematically represents the first critical stress state I as a block, where in Fig. 1. On the right, the second critical stress state II is shown as a second block. Within each block, the individual process steps are then subdivided accordingly and also shown schematically; this should be noted in advance. The vehicle electrical system itself is shown schematically in "box form". In the Fig. In the box-shaped representation shown in Figure 1, the electrical system is depicted as the outer box / outer border, with the first critical stress state I essentially represented as a block on the left and the second critical stress state II essentially represented as a block on the right. The individual process steps are then numbered within the blocks, with arrows indicating the sequence of events, at least partially. For the sake of clarity, components such as the control unit, cables, parking brake, parking lock, and / or the vehicle itself are not shown in detail here.

[0035] The inventive method may now be explained in such a way that the first critical stress state I is first explained in more detail, i.e. the individual process steps are explained in more detail here in the first critical stress state I: Basically, the vehicle speed is determined and / or monitored, in particular permanently or continuously. At least in the first critical voltage state I, the vehicle's movement or speed is monitored so that if the vehicle is detected as stationary, the control unit requests the parking brake to be applied, and in particular, the parking brake is applied automatically. This is in the Fig. 1 represented by process step 2.

[0036] In the event that the parking brake fails to engage, or does not engage fully, and / or with insufficient braking force, particularly due to a malfunction, the parking lock in the vehicle's transmission is also engaged. This is described in the Fig. Figure 1 illustrates process step 3. However, the parking lock is only effectively engaged in the vehicle's transmission if the electric parking brake cannot be effectively activated.

[0037] The parking brake can be opened manually by pressing an EPB button, or it can be opened automatically when the vehicle starts moving, particularly when the driver presses the accelerator pedal and / or engages or selects a gear other than parking (P). In other words, in the first critical voltage state, the driver can intentionally continue moving the vehicle, especially by driving, and signals this by pressing the accelerator pedal and / or engaging a gear other than parking (P), particularly by selecting drive (D). This is in Fig. 1 is represented by process step 4.

[0038] If, after coming to a standstill, the vehicle starts moving again during the determination of the first critical voltage state and exceeds a certain speed threshold, in particular exceeding a certain minimum speed and / or a certain time period has elapsed, the control system restarts the process. This is in Fig. 1 is represented by process step 5.

[0039] However, if vehicle movement is detected, or if the vehicle speed reaches a certain minimum value, specifically v > 0 km / h, meaning the vehicle is not stationary during the determination of the first critical voltage state I, then the parking brake and / or parking lock will not engage. In other words, the parking brake and / or parking lock will not be controlled, and in particular, not activated. This is in the Fig. This is illustrated by step 6 of the procedure. It should be noted in particular that if the vehicle is found to be stationary, this is also indicated in blocks (I and II) by the respective designation v ≈ 0 km / h. Therefore, vehicle stationary is represented by v ≈ 0 km / h, and vehicle movement or a vehicle speed is represented by v > 0 km / h. It should be noted that a "vehicle stationary" can also occur if only a very low speed, for example, "< 0.5 km / h", is determined. For this reason, a vehicle stationary is schematically symbolized in those blocks by "v ≈ 0 km / h", and this should be emphasized again. A "vehicle stationary" in the sense defined here can therefore also occur if v < 0.5 km / h.

[0040] In Fig. Figure 1 shows the procedural steps for determining and / or in the event of a second critical stress state II.

[0041] As explained above, step 1b first issues a corresponding warning message, whereby the movement of the vehicle and / or the vehicle speed is determined and / or continuously detected, especially during a second critical voltage state II.

[0042] At least in the second critical stress state II, the vehicle's movement or speed is monitored, and if the vehicle is detected as stationary, the control system requests that the parking brake be applied, in particular, that the parking brake be applied automatically. The latter is described in process step 7 in Fig. Figure 1 illustrates this. This process step 7 is therefore initially similar to process step 2, but now, particularly when the second critical stress state II is present, the parking lock in the vehicle's transmission is always engaged in process step 7, specifically the "parking gear P" (in the transmission) is engaged or activated. This ensures that the vehicle is rolling away, essentially independent of whether the parking brake is actually engaged or functioning. This is illustrated here in process step 7. Simply put, regardless of whether the parking brake is engaged in the second critical stress state II, or whether it cannot be engaged due to a fault and / or circumstance, at least the parking lock in the vehicle's transmission is automatically engaged (see process step 7).

[0043] The parking brake can be released manually by pressing the EPB button and / or it can be released automatically when the vehicle starts moving, particularly when the driver presses the accelerator pedal. However, the latter only occurs if the driver engages a gear other than parking (P) or selects such a gear, for example, forward (D), or signals to the control system that a gear other than parking (P) is desired. This is described in procedure step 8 in... Fig. Figure 1 shows that this allows the engaged parking lock to be deactivated, i.e., released, so that the driver can move the vehicle again, especially for a very short time; in particular, the vehicle could then be moved onto a tow truck or loaded onto one.

[0044] The aforementioned procedural steps 7 and 8 are carried out with the vehicle at a standstill during the determination or occurrence of the second critical stress state II.

[0045] However, if the second critical voltage state II is detected and the vehicle is moving, i.e., driving, the vehicle is no longer stationary. In the second critical voltage state II, the vehicle's movement is also monitored, and then, at a determined driving speed outside of a stationary state, a driving torque limitation is implemented by appropriately controlling the vehicle's drive motor and / or transmission. This limits and / or reduces the vehicle's maximum achievable speed. This aspect serves, for example, to ensure that when the vehicle is traveling on a country road or highway and the second critical voltage state II of the vehicle's electrical system is detected, the driver is more or less forced to stop and / or park the vehicle as soon as possible. This is described in procedure step 9 in Fig. Figure 1 illustrates this. Simultaneously, a warning message is generated and / or displayed to the driver, particularly visually and / or audibly. This warning message includes, at a minimum, an indication to the driver that the vehicle's speed is being limited and / or that an acute vehicle malfunction has occurred. This also occurs in step 9. After a certain period of time, particularly after 60 seconds, the parking lock in the transmission is unconditionally, and in particular immediately, engaged by the control system. The term "engaged by the control system" means that the parking lock is controlled in such a way that it can be engaged in the transmission, but is not necessarily yet effectively engaged. In particular, it is not effectively engaged if the vehicle speed has not yet fallen below a certain threshold, in particular 2.5 km / h.Only when the vehicle speed falls below a certain threshold, specifically below the aforementioned 2.5 km / h, will the parking lock be effectively engaged in the transmission. A mechanical device is integrated into the transmission to enable the parking lock to be engaged, but it will only engage once the vehicle speed has dropped below a certain threshold. This prevents the parking lock from engaging at higher speeds. The time interval for this process is described in step 10. Fig. Figure 1 shows the unconditional engagement of the parking lock, particularly in step 11 in Fig. 1 should be shown.

[0046] Additionally, particularly in step 11, the power transmission between the transmission and the vehicle's drive motor is disconnected and / or a specific warning message is generated and / or displayed to the driver. This warning message specifically informs the driver that the transmission has a defect and / or that the vehicle should be stopped as soon as possible.

[0047] Only when the vehicle has started moving again after a detected standstill during the second critical voltage state and has exceeded a certain speed threshold and / or a certain time period has elapsed, does the control procedure start again from the beginning.

[0048] The aforementioned method according to the invention offers a multitude of advantages. For its implementation, the method comprises, in particular, an electrical and / or electronic control unit (not shown here), specifically a microprocessor and / or several monitoring units, especially for monitoring the current voltage of the vehicle's electrical system. Also included are corresponding sensors for determining the vehicle speed, processors for implementing time intervals (timers), and corresponding electric drive motors and / or actuators for controlling the electric parking brake and / or the electric parking lock.

[0049] As a result, the method according to the invention makes it possible, in particular, to control a purely electrically operated parking brake and a purely electrically operated parking lock as reliably as possible, even if the vehicle's electrical system is at risk of failing in the near or medium term. For this purpose, corresponding critical voltage states are determined beforehand, and specific control mechanisms for the electric parking brake and the electric parking lock are then implemented for the respective defined voltage states, as described above. Reference symbol list I first critical stress state II second critical stress state 1a Issue Warning Message 1b Issue Warning Message 2. Request to close the parking brake 3. Additional engagement of the parking lock in the gearbox in case of parking brake failure 4. Driving on by releasing the parking brake (via EPB button and / or automatically when the vehicle starts moving) or by selecting a driving mode outside of parking mode P 5. Procedure starts again 6. No intervention by parking brake or parking lock outside of vehicle standstill, i.e. at v > 0 km / h 7. Closing the parking brake is requested by the control unit, especially the transmission, but always requires additional engagement of the parking lock. 8. Selection of a driving mode other than P, thereby enabling further driving and / or opening of a parking brake or engaging the parking lock. 9. Driving torque limitation and / or warning message for driver when v > 0 km / h 10. Expiration of a period of time 11. Unconditional engagement of the parking lock P driving mode, especially parking mode Drive mode / Forward drive mode QUOTES INCLUDED IN THE DESCRIPTION

[0000] This list of documents cited by the applicant was automatically generated and is included solely for the reader's convenience. The list is not part of the German patent or utility model application. The DPMA accepts no liability for any errors or omissions. Cited patent literature

[0000] DE 102017211398 A1

[0004] DE 102018215605 A1

[0005]

Claims

[1] Method for controlling an electric parking brake and / or an electric parking lock of a vehicle, in particular a motor vehicle, wherein the parking brake and the parking lock are electrically controlled and / or electrically operated for the respective engagement and / or disengagement, wherein an electrical vehicle electrical system for providing electrical energy, in particular a 12V low-voltage network, is provided and / or available for the respective control of the parking brake and / or the parking lock, wherein the voltage level of the electrical vehicle electrical system is monitored, in particular continuously, wherein a -first- critical voltage state (I) is reached when a -first- certain voltage level is undershot, and wherein a rolling protection of the vehicle is achieved by a corresponding first specific control of the parking brake and / or the parking lock,when the first critical voltage state (I) of the vehicle electrical system is determined and / or detected, characterized by , that a second critical voltage state (II) of the vehicle electrical system - which differs from the first critical voltage state (I) of the vehicle electrical system - can be determined and / or detected when a second specific voltage level is undershot, wherein the second specific voltage level is lower than the first specific voltage level, and that the vehicle's rolling protection is then implemented by a corresponding second specific control of the parking brake and / or the parking lock - which differs from the first specific control - when the second critical voltage state (II) is determined and / or detected. [2] Method according to claim 1, characterized by, that in the first critical voltage state (I) and / or in the second critical voltage state (II) a warning message is generated and / or issued for the driver of the vehicle, in particular wherein in the first critical voltage state (I) the warning message “Please drive carefully” and / or “Please visit a workshop” and / or in the second critical voltage state (II) the warning message “Stop vehicle” is generated and / or issued. [3] Method according to claim 1 or 2, characterized by , that in the first critical voltage state (I) the movement or vehicle speed of the vehicle is monitored and, in the event of a detected vehicle standstill, the control system requests that the parking brake be closed, in particular that the parking brake is closed automatically. [4] Method according to claim 3, characterized by, that in the event that the parking brake is not closed, or not fully closed and / or with insufficient braking force, particularly due to a malfunction, the parking lock in the vehicle's gearbox will also be engaged. [5] Method according to claim 3 or 4, characterized by , that the parking brake can be opened by manually pressing an EPB button or that the parking brake opens automatically when the vehicle starts moving, in particular when the driver presses the accelerator pedal, and / or when a driving gear other than the parking gear ("P") is engaged or selected by the driver. [6] Method according to any one of claims 3 to 5, characterized by , that if the vehicle starts moving again after coming to a standstill and exceeds a certain speed threshold and / or a certain time period has elapsed, then the control procedure starts again from the beginning. [7] Method according to any one of claims 3 to 6, characterized by , that outside of a vehicle standstill, i.e. when the vehicle is moving, no interventions are made by the parking brake or by the parking lock. [8] Method according to any one of the preceding claims, characterized by , that in the second critical voltage state (II) a movement or vehicle speed of the vehicle is monitored and if a vehicle standstill is detected, the control system requests that the parking brake be closed, in particular that the parking brake is closed automatically. [9] Method according to claim 8, characterized by , that the parking lock is engaged in the vehicle's gearbox, in particular that the parking gear ("P") is engaged in the gearbox. [10] Method according to claim 9, characterized by, that the parking brake can be opened by manually pressing the EPB button and / or that the parking brake opens automatically when the vehicle starts moving, in particular when the driver presses the accelerator pedal, and a driving gear other than the parking gear ("P") is engaged or selected by the driver. [11] Method according to any one of claims 8 to 10, characterized by , that in the second critical stress state (II) a movement or vehicle speed of the vehicle is monitored and, at a determined driving speed outside of a vehicle standstill, a driving torque limitation is realized by the corresponding control of the drive motor and / or the transmission, in particular the possible speed achievable of the vehicle is thereby limited and / or reduced. [12] Method according to claim 11, characterized by, that a warning message is generated and / or issued to the driver, the warning message including at least the indication to the driver that the speed of the vehicle is being limited and / or that there is an acute malfunction of the vehicle. [13] Method according to claim 11 or 12, characterized by , that after a certain period of time, in particular after the expiry of 60 seconds, the parking lock in the transmission is unconditionally, in particular immediately, engaged by the control system, in particular whereby the parking lock in the transmission is only effectively engaged when the vehicle speed has fallen below a certain limit, in particular 2.5 km / h. [14] Method according to claim 13, characterized by, that the power transmission between the gearbox and the drive motor is interrupted and / or a specific warning message is generated and / or issued to the driver, in particular where the warning message includes the instruction to the driver that the gearbox has a defect and / or that the vehicle should be stopped as soon as possible. [15] Method according to any one of claims 8 to 14, characterized by , that if the vehicle has started moving again after a standstill and has exceeded a certain speed threshold and / or a certain period of time has elapsed, then the control procedure starts again from the beginning.

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