Method for informing a driver of a motor vehicle of a fault associated with a motor vehicle braking system

Abstract

The invention relates to a method for informing a driver of a motor vehicle about a fault associated with a brake system of the motor vehicle, wherein the method has the following steps: recognizing the fault, detecting brake pedal actuation information if the brake pedal is actuated, the brake pedal actuation information describing an actuation path of the brake pedal through actuation, determining brake torque information in the event that a fault situation brake torque determination criterion is applied to the detected brake pedal actuation information, the brake torque information describing a brake torque for at least one wheel brake, wherein the determined brake torque is less than one third of a typical brake torque if the actuation path traveled through is less than one third of a maximum actuation path, but the determined brake torque information describes a maximum brake torque if the maximum actuation path is traveled through, and loading the at least one wheel brake with the brake torque described by the determined brake torque information.

Description

Technical Field

[0001] This invention relates to a method for notifying a driver of a motor vehicle of a malfunction associated with the vehicle's braking system. The invention also relates to a motor vehicle configured to perform this method. Background Technology

[0002] Currently, motor vehicles typically have a braking system with at least one wheel brake associated with each wheel of the vehicle. This wheel brake is usually operated with consideration of manual operation of the brake pedal by the driver. Here, the operation can be performed purely electronically, wherein the operating device and the actuating device of the braking system are preferably mechanically decoupled from each other. Here, the operating device is the brake pedal and the actuating device is, for example, the wheel brake associated with at least one wheel of the vehicle. This type of braking system is called brake-by-wire.

[0003] A vehicle is known from US2018 / 0194353A1, in which a mode is set for fault conditions, in which stronger brake pedal operation is required to achieve the desired braking of the vehicle. Summary of the Invention

[0004] The objective of this invention is to provide a solution by which a driver of a motor vehicle is notified that a fault has occurred in the motor vehicle that can be associated with the vehicle's braking system.

[0005] The task is accomplished by a method for notifying the driver of a motor vehicle of a malfunction associated with the vehicle's braking system and by a motor vehicle having a braking system.

[0006] This invention is based on the understanding that it is meaningful to inform the driver of a malfunction related to the braking system in a motor vehicle. This is especially true when the malfunction may lead to a deterioration in the braking system's function due to subsequent malfunctions, as it increases the probability of such subsequent malfunctions. This is always the case, for example, when the braking system itself can still function due to the malfunction (because the backup system can still function), but when a subsequent malfunction occurs, braking may only be possible with reduced braking system functionality. Therefore, for example, in the case of a subsequent malfunction, braking can only be performed at two of the four wheels using the corresponding wheel brakes located there.

[0007] Therefore, the driver needs to be informed that the braking system has a probability of failure or at least partial failure in the near future. Visual indications output in the vehicle, such as warning lights and / or warning displays on the vehicle's display device, are suitable for this notification to the driver. Alternatively or additionally, the notification can be made using acoustic indications, such as warning sounds output in the vehicle. However, such visual and / or acoustic indications are often not understood and / or ignored by the driver. Therefore, it is meaningful to notify the driver of the malfunction in an alternative manner, for example, besides visual and / or acoustic indications. Tactile feedback to the driver is suitable for this, which can be achieved, for example, by changing the pedal feel. The driver can be informed, for example, by changing the correlation between manual brake pedal operation performed by the driver and the braking torque applied to at least one wheel brake of the vehicle in a fault-free normal operation compared to a fault-free normal operation. For example, tactile feedback can be achieved by initially setting a free travel. This means that in a fault-free situation, the braking deceleration is adjusted to be smaller than in a fault-free normal operation under specific brake pedal operation conditions. Furthermore, one advantage of this warning indication is that it eliminates the need for a brake pedal with active actuators in the motor vehicle to provide tactile feedback that is perceptible to the driver, since the resulting tactile feedback is achieved solely through a change in the brake pedal force characteristic line, i.e., a change in the correlation between brake pedal operation and braking torque.

[0008] The method according to the invention is used to notify the driver of a motor vehicle of a fault associated with the vehicle's braking system. A fault associated with the vehicle's braking system is a fault involving the braking system, i.e., a fault related to the braking system. Such faults are, for example, electrical faults, such as electrical faults in the vehicle's onboard network, leaks in the hydraulic wheel brakes of the braking system, and / or overheating of at least one wheel brake of the motor vehicle at high ambient temperatures.

[0009] The braking system includes a brake pedal, at least one wheel brake associated with a wheel of the vehicle, and a brake pedal sensor device. The at least one wheel brake can be electronically controlled while taking into account manual operation of the brake pedal. For this purpose, the position of the brake pedal is detected, for example, by means of the brake pedal sensor device when the driver manually operates the brake pedal, and this is provided and evaluated as corresponding brake pedal sensor data for controlling the wheel brake. The braking system is therefore a so-called brake-by-wire system. The brake pedal is thus mechanically decoupled from the at least one wheel brake. The vehicle preferably has at least one wheel brake for each wheel, i.e., for example, four preferably hydraulic wheel brakes in the case of four wheels. Furthermore, in addition to the four hydraulic wheel brakes, the braking system preferably has an electronic parking brake for each rear wheel of the vehicle, for example, at each wheel of the rear axle. The at least one wheel brake can alternatively be called a brake actuator. Each wheel brake is configured to brake the associated wheel of the vehicle according to the applied braking torque when a braking torque is applied. The braking system preferably includes a control device by which the at least one wheel brake can be electronically operated while taking into account manual operation of the brake pedal. The control device may also be configured to evaluate brake pedal sensor data detected by the brake pedal sensor device. The control device preferably includes a processor.

[0010] The method includes the following steps: confirming a fault associated with the vehicle's braking system. However, despite the confirmed fault, the brake pedal sensor device remains functional, the at least one wheel brake remains operable, and the brake pedal remains operable. Therefore, the braking system continues to function. Here, the operable braking system can be the primary braking system of the vehicle, but it can also be a secondary braking system, and for example, a backup braking system is provided in the event of a fault. The confirmed fault is, for example, a leak in one of the hydraulic wheel brakes, thus, for example, the wheel brake associated with at least one of the wheels of the vehicle is faulty and no longer functional. If a subsequent fault now occurs, the braking system may become unable to brake. Therefore, in this example, there is a fault associated with the vehicle's braking system, and in the event of this fault, the driver should be notified of the fault. This is because the fault itself and, in particular, the likely subsequent faults, affect the functional operation of the braking system. Therefore, the driver should be notified of the fault, namely, the leak in one of the hydraulic wheel brakes.

[0011] If the brake pedal is actuated, i.e., if the driver manually actuates the brake pedal, brake pedal actuation information is preferably detected by means of a brake pedal sensor device. Brake pedal actuation information describes the actuation distance of the brake pedal by actuation. The actuation distance of the brake pedal may alternatively be referred to as the brake pedal travel. For example, brake pedal actuation information can be determined by evaluating brake pedal sensor data from the brake pedal sensor device. This evaluation step can be performed, for example, by means of a control device for the braking system that has an evaluation algorithm for this purpose.

[0012] Furthermore, it is preferable to measure braking torque information, which describes the braking torque for the at least one wheel brake. The braking torque information is measured when a fault-condition braking torque determination criterion is applied to the detected brake pedal operation information. The fault-condition braking torque determination criterion is an algorithm and / or rule describing the correlation between the operating travel of the brake pedal and the braking torque to be adjusted based on that operating travel. The braking torque information is measured when the fault-condition braking torque determination criterion is applied, including: if the operated travel is less than at least one-third of the maximum operating travel that can be maximized when the brake pedal is operated, then the measured braking torque is less than one-third of a typical braking torque, which is determined when a normal-condition braking torque determination criterion, different from the fault-condition braking torque determination criterion and applied when a fault is not confirmed, is applied to the detected operation information. Therefore, at least for the first third of the possible operating travel of the brake pedal, a correlation between operating travel and braking torque is assumed that differs from the correlation assumed for a fault-free normal condition. The correlation set for normal, fault-free conditions is stored in the normal-condition braking torque determination criterion, i.e., preset by the normal-condition braking torque determination criterion. The fault-condition braking torque determination criterion is applied only when no normal condition exists, for example, because a fault has occurred. Compared to the normal-condition braking torque determination criterion, the fault-condition braking torque determination criterion sets a reduction in braking torque for small operating strokes, more precisely, a reduction to the maximum one-third of the typical braking torque for normal conditions. Furthermore, this reduction is limited such that it only occurs when the operating value is at most one-third of the maximum operating stroke of the brake pedal. Alternatively, the maximum operating stroke may be referred to as the maximum operating stroke of the brake pedal. The maximum operating value is fixedly preset by the brake pedal, i.e., preset in an unchangeable manner due to its design. Therefore, at the start of brake pedal operation, i.e., at the first one-third of the maximum operating stroke, less strong braking occurs compared to a fault-free normal condition.

[0013] However, under the condition of maximum braking torque, the maximum possible braking power, i.e., the maximum braking torque, is achieved. Therefore, the reduction of braking torque is stopped at least when the maximum operating stroke is reached, because the at least one wheel brake is configured to be loaded with maximum braking torque. Therefore, at least under the condition of maximum operating stroke, the criteria for determining the braking torque in fault conditions are consistent with the criteria for determining the braking torque in normal conditions.

[0014] In the final step of the method, it is preferable to apply the braking torque described by the measured braking torque information to the at least one wheel brake. Therefore, the braking torque determined by applying the fault-condition braking torque determination standard, i.e., the measured braking torque information, is actually used to operate the wheel brakes. In other words, the at least one wheel brake is applied according to the measured braking torque information. Thus, the motor vehicle is preferably braked.

[0015] Due to the delayed braking response when the operating travel is less than one-third of the maximum operating travel, the driver notices a deviation in the vehicle's braking response to brake pedal operation compared to normal conditions, as the braking torque is adjusted to be weaker than in a fault-free normal situation. However, if the driver, for example, does indeed expect emergency braking, this continues in the usual manner, since in the case of maximum operating travel, the maximum braking torque is determined as braking torque information and is achieved by accordingly applying the brakes to at least one wheel.

[0016] The determination of braking torque information and the application of the brakes of the at least one wheel based on the determined braking torque information are preferably performed by means of the control equipment of the braking system.

[0017] Based on the measured braking torque information, a fault associated with the vehicle's braking system can be reliably communicated to the driver, as the final tactile indication is achieved through the altered correlation between the brake pedal travel and the applied braking torque, and is perceived by the driver through touch. However, it is ensured that, in cases of desired emergency braking, the maximum braking torque does not decrease undesirably, if possible.

[0018] In cases where the brake pedal travel is greater than one-third but less than the maximum travel, the braking torque information for the increased brake pedal travel can be set to increase continuously and / or more steeply compared to the first one-third. However, the correlation between the braking torque information and the brake pedal travel information preferably continues to differ from the corresponding correlation determined according to the braking torque standard under normal conditions.

[0019] In addition to the measures provided according to the invention for notifying the driver by means of tactile indication, it can also be configured to additionally output visual and / or auditory indications for corresponding malfunctions in the motor vehicle. For this purpose, for example, a warning symbol may be displayed on a display device, a warning light may be activated, and voice and / or warning sounds may be output via a speaker device in the motor vehicle.

[0020] According to one embodiment, if the traveled actuation distance is less than one-third of the maximum actuation distance, the measured braking torque information is zero. Therefore, instead of a preset braking torque that is reduced to at least one-third of the typical braking torque, the first third of the maximum actuation distance can thus be fixed as a no-travel period. In other words, in this case, the vehicle only responds to the driver's actuation of the brake pedal after at least one-third of the maximum actuation distance has been traveled via brake pedal actuation. If, for example, only one-quarter of the maximum actuation distance has been traveled when the brake pedal is actuated, then no braking torque is applied to the at least one wheel brake; that is, in this case, the vehicle is not braked at all. This is a particularly clear signal to the driver that something is wrong with the braking system, thus allowing for particularly reliable notification of the driver of any malfunction associated with the braking system.

[0021] Another embodiment is configured to determine an operating speed value that describes the speed at which the brake pedal is operated. That is, to determine how quickly the driver operates the brake pedal, i.e., within what time period a specific operating stroke of the brake pedal is traveled. If the operating speed value is greater than an operating speed limit, a normal braking torque determination criterion is applied. In cases where the brake pedal is preferably operated particularly quickly, the braking force can be adjusted for each travel of the pedal travel to a greater extent than the fault braking torque determination criterion actually sets for the total travel of the pedal travel.

[0022] This embodiment is based on the understanding that an operating speed exceeding the operating speed limit indicates an emergency braking situation. In such an emergency braking situation, an unnecessarily long braking distance should not be provided. For this reason, in this case, the normal-condition braking torque determination standard set for fault-free normal conditions is applied instead of the fault-free condition braking torque determination standard.

[0023] Alternatively, one embodiment is configured to measure an operating speed value that describes the speed at which the brake pedal is operated. That is, to determine how quickly the driver operates the brake pedal, i.e., within what time period a specific operating stroke of the brake pedal is completed. If it is confirmed that the operating speed value is greater than the operating speed limit, then an intermediate-condition braking torque determination standard is applied. This standard differs from the fault-condition braking torque determination standard and the normal-condition braking torque determination standard. Therefore, it may be modified according to the speed at which the brake pedal is operated, as well as any possible deviations from the fault-condition braking torque determination standard, particularly to the intermediate-condition braking torque determination standard.

[0024] The intermediate-condition braking torque determination criterion associates an intermediate-condition braking torque information with each brake pedal operation, which is greater than the braking torque information measured when applying the fault-condition braking torque determination criterion. Specifically, it measures braking torque information that is greater than the braking torque information determined according to the fault-condition braking torque determination criterion. However, this braking torque information is preferably less than the braking torque information determined according to the normal-condition braking torque determination criterion. For this reason, this braking torque information is called intermediate-condition braking torque information. Therefore, braking torque information is set that lies between the normal-condition braking torque information and the fault-condition braking torque information. Due to the high speed of brake pedal operation, an intermediate phase of braking torque applied between normal and fault conditions can be activated. This achieves the following: despite the high operating speed when operating the brake pedal, a tactile indication is still sent to the driver, that is, to notify the driver of a fault, because there is still a deviation from the standard for determining the braking torque under normal conditions. That is, instead of using the braking torque used to operate the wheel brakes under normal, fault-free conditions, a different braking torque information is used, namely, intermediate-condition braking torque information.

[0025] One particularly advantageous embodiment is configured such that the motor vehicle has an energy supply component and a drive system. The drive system has an accelerator pedal and a drive mechanism for longitudinal control of the motor vehicle. The drive mechanism can be electronically controlled while taking into account manual operation of the accelerator pedal. The drive mechanism is, for example, a motor, such as an electric motor and / or an internal combustion engine of the motor vehicle. The drive system may further have a control device, which may be referred to as a drive control device, and the drive mechanism can be electronically controlled by means of this control device while taking into account manual operation of the accelerator pedal. The motor vehicle thus has a drive system based on drive-by-wire. In other words, the accelerator pedal and the drive mechanism for longitudinal control of the motor vehicle are mechanically decoupled.

[0026] A fault associated with the energy supply component is now identified, wherein, despite the identification of the fault, the at least one wheel brake and drive unit can be controlled with regard to corresponding manual operation. For example, the impending failure of the energy supply component can be identified, for example, with a one-minute lead time, using a sensor device in the vehicle's high-voltage battery that detects, for example, a sudden voltage drop. The remaining energy of the energy supply component can then be inferred, and thus, for example, the expected time of complete or at least partial failure of the braking system due to lack of energy supply can be predicted. The failure of the braking system is a consequence of the energy supply component failure. Such a fault is, for example, referred to as a fault associated with the energy supply component.

[0027] If a fault associated with the energy supply component is confirmed, the vehicle can be accelerated using the drive system while the brake pedal is pressed and subsequently the accelerator pedal is engaged. Acceleration is only permitted after a preset waiting period, taking into account the manual operation of the accelerator pedal. A dead time is set, which is activated upon release of the brake pedal followed by accelerator pedal engagement. The dead time is preferably a few seconds, such as 2, 3, 4, 5, or 10 seconds. By implementing this waiting period after confirming a fault associated with the energy supply component and in the event of desired acceleration, the driver is tactilely notified of the presence of a fault.

[0028] The faults associated with the energy supply components present here are also faults associated with the vehicle's braking system, since the energy supply components for the braking system are affected. However, these faults are considered a special case, and the driver is therefore notified of them in a different manner and thus differentiatedly. Ultimately, based on the vehicle's drive system's response to accelerator pedal manipulation, the driver can be notified of faults associated with the vehicle's energy supply components. Here, the type of notification differs from that in the general fault cases involving the braking system described above. Ultimately, the relationship between acceleration, i.e., the vehicle's propulsion power, and accelerator pedal manipulation caused by the confirmed fault associated with the energy supply components is altered, thus making the driver aware of the possible vehicle condition due to the fault, not only solely due to the change in response of the brake pedal, but also due to the change in the vehicle's response after the accelerator pedal is manipulated. The driver is therefore notified of faults associated with the energy supply components particularly reliably because the delayed response of the accelerator pedal is tactilely perceptible.

[0029] According to another embodiment, after a fault associated with the energy supply component is confirmed, the drive unit and / or the at least one wheel brake are manipulated to reduce the current propulsion power of the vehicle. The current propulsion power is preferably reduced by a propulsion power value. The propulsion power value can be preset to a constant value. Alternatively, a time-dependent reduction can be implemented, i.e., the propulsion power value increases over time. For example, the vehicle's acceleration can be reduced, for example, by automatically reducing the vehicle's acceleration preset by the drive unit. Alternatively or additionally, the at least one wheel brake can be applied with a preset braking torque to actively brake the vehicle. This allows for an early response to the possibility that the braking system may no longer have an energy supply in the near future, in a way that the reduction in propulsion power can ultimately trigger a simple decrease in the vehicle's speed. This results in the vehicle being brought to a standstill earlier than the energy supply component actually fails.

[0030] Furthermore, one embodiment is configured such that the at least one wheel brake is an electronic parking brake, which is brought to a persistently active state after a failure of the energy supply component is confirmed. The electronic parking brake is, for example, located at the corresponding rear wheel of the vehicle; that is, the electronic parking brake is associated with and configured to brake the corresponding rear wheel and / or hold it in a braking state. In the persistently active state, persistent braking intervention is performed by the electronic parking brake, which is maintained even in the event of a loss of energy supply to the braking system, because an electronic parking brake without energy supply cannot be brought from the persistently active state to a deactivated state.

[0031] When the accelerator pedal of a motor vehicle is operated, the vehicle can continue to be driven even though the electronic parking brake is in a persistently active state. The vehicle can thus continue to accelerate, for example, by operating the accelerator pedal; however, compared to the normal situation where the parking brake is not in a persistently active state, this acceleration—that is, the propulsive power of the vehicle—is reduced in relation to the operation of the accelerator pedal. The degree of reduction is determined by the braking power of the persistently active parking brake. If the energy supply to the braking system is indeed completely lost, for example as a consequence of the confirmed fault, the drive unit will also cease to supply energy to the vehicle due to the lack of energy supply, and thus the vehicle cannot accelerate further. However, the electronic parking brake remains in a persistently active state, so that even without an energy supply to the braking system, the vehicle can still be braked to a standstill, for example, by means of the already activated parking brake. Therefore, measures are taken to reliably bring the vehicle to a standstill in the event that the vehicle's energy supply component has indeed failed. Thus, the driver is not only informed of the energy supply failure but also that measures have been taken in the event that the energy supply component has indeed failed.

[0032] Alternatively or additionally, when activating the electronic parking brake, in the case of hydraulic wheel brakes, locking of the braking pressure at at least one wheel brake can be activated when the valve is closed in the absence of current. This also allows the vehicle to be braked by means of at least one wheel brake that has been switched in this manner, even if the vehicle's energy supply is indeed depleted. Preferably, a sustained braking torque is always applied to at least two wheel brakes arranged along the lateral direction of the vehicle on two different sides.

[0033] According to a particularly preferred embodiment, the motor vehicle is configured with a drive system including: an accelerator pedal; and a drive mechanism for longitudinal control of the motor vehicle, the drive mechanism being electronically operable while taking into account manual operation of the accelerator pedal. Furthermore, the drive system includes an accelerator pedal sensor device capable of detecting accelerator pedal operation. Now, there is a situation where, due to a confirmed fault associated with the motor vehicle's braking system, the brake pedal sensor device is inoperable. The at least one wheel brake is now applied with a preset basic braking torque. Therefore, due to the confirmed defective brake pedal sensor device, the motor vehicle is braked, more precisely, braked according to the prescribed basic braking torque. Therefore, the vehicle's speed is reduced by targeted braking intervention, in which the at least one wheel brake is applied with a preset basic braking torque.

[0034] If the accelerator pedal is operated under these circumstances—that is, preferably if the driver operates the accelerator pedal with a preset basic braking torque despite confirming a malfunction—accelerator pedal operation information is detected. Accelerator pedal operation information is detected using an accelerator pedal sensor device. Accelerator pedal operation information describes the travel distance of the accelerator pedal through operation. Therefore, similar to brake pedal operation information, corresponding information concerning accelerator pedal operation is detected. Then, if the detected accelerator pedal operation information is less than the accelerator pedal operation limit, a special case braking torque less than the basic braking torque is applied to the at least one wheel brake. When the brake pedal sensor device is inoperable, the special case braking torque may alternatively be referred to as the malfunction braking torque. If the driver only lightly operates the accelerator pedal due to the accelerator pedal operation information being less than the accelerator pedal operation limit, this will result in a retraction of the already occurring braking deceleration, because a less large braking torque, i.e., a braking torque smaller than the currently preset basic braking torque, is selected. The achieved braking deceleration is thus reduced and retracted. Therefore, compared to the currently occurring braking, the driver's acceleration expectation is thus converted into reduced braking of the vehicle.

[0035] If the detected accelerator pedal operation information is greater than or equal to the accelerator pedal operation limit, acceleration information is measured when the fault-condition acceleration determination criterion is applied to the detected accelerator pedal operation information. This acceleration information describes the acceleration of the vehicle. The drive unit is manipulated in such a way that the vehicle accelerates according to the acceleration information. Acceleration of the vehicle is possible when the accelerator pedal operation is set to be stronger than the accelerator pedal operation limit, because the acceleration information is then measured. However, for this to be possible, the driver must depress the accelerator pedal significantly more forcefully and therefore further than would be necessary under normal conditions without a fault in the brake pedal sensor device. In other words, a fault-condition acceleration determination criterion is applied, rather than the normal-condition acceleration determination criterion used under fault-free conditions.

[0036] Fault acceleration determination criteria include algorithms and / or rules that correlate the accelerator pedal travel with the desired acceleration, i.e., acceleration information. In other words, fault acceleration determination criteria include the accelerator pedal operating characteristic line for the motor vehicle's drive system. Therefore, fault acceleration determination criteria involve the correlation between accelerator pedal travel and the vehicle's acceleration.

[0037] Therefore, when the accelerator pedal is operated, a fault is detected, and the driver is notified of the presence of a fault due to the different types of effects on the vehicle's acceleration compared to normal, fault-free conditions caused by the accelerator pedal operation. Therefore, a special fault-specific tactile indicator is provided for the driver, indicating a fault in the vehicle related to the braking system.

[0038] One embodiment is configured such that if the detected accelerator pedal manipulation information is less than the accelerator pedal manipulation limit, the vehicle is not accelerated, taking into account the detected accelerator pedal manipulation information. In other words, the vehicle is only braked and not accelerated at all when the accelerator pedal manipulation information indicates accelerator pedal manipulation below the accelerator pedal manipulation limit. Therefore, although the accelerator pedal is manipulated, in this case, the vehicle's propulsion power is not increased compared to the current propulsion power caused by the applied basic braking torque. Thus, for example, if the driver only slightly manipulates the accelerator pedal, the driver then confirms that the vehicle is not accelerating, but rather that only braking of the vehicle is still occurring. The driver can react to this tactile feedback, for example, by ceasing to manipulate the accelerator pedal and allowing the vehicle to be braked to a standstill by means of a preset basic braking torque, which has been applied to at least one wheel brake. During braking of the vehicle according to the applied basic braking torque, the driver can, for example, continue to steer the vehicle, for example, by means of the vehicle's steering system, and, for example, manipulate the stop position at the edge of the road on which the vehicle is currently traveling.

[0039] According to one embodiment, the measured acceleration information is configured to be less than typical acceleration information, which is determined when a normal acceleration determination standard, different from the fault-condition acceleration determination standard and applied when the fault is not confirmed, is applied to the detected accelerator pedal operation information. Even though the accelerator pedal operation range is reached, exceeding the accelerator pedal operation limit, and the vehicle continues to accelerate within this range, it is configured to accelerate with less intensity than in a fault-free normal situation. This achieves the goal that the vehicle cannot accelerate as it would if the brake pedal sensor device were functioning, because the brake pedal sensor device is malfunctioning. Therefore, the driver should be clearly informed that something is wrong with the vehicle because the driver cannot achieve his accustomed acceleration. This may stimulate the driver and thus be experienced as a tactile warning. Thus, this measure achieves the goal of informing the driver of a malfunction related to the brake pedal sensor device associated with the vehicle's braking system.

[0040] Furthermore, it can be configured to set a pre-accelerator pedal operating limit value, which is less than the accelerator pedal operating limit value. When the accelerator pedal operating information is between the pre-accelerator pedal operating limit value and the accelerator pedal operating limit value, it is configured such that neither the at least one wheel brake is applied with a preset braking torque, nor the drive device is operated in such a way that the vehicle accelerates with a positive acceleration. Instead, the vehicle may, for example, simply continue to roll, thereby braking the vehicle, for example, due to friction, preferably without the action of a braking system. Therefore, a free travel for the accelerator pedal is provided. Free travel is an additional tactile indication for the driver, because although the accelerator pedal is operated, the driver cannot achieve acceleration of the vehicle.

[0041] Furthermore, one embodiment is configured such that, after the accelerator pedal is actuated, the at least one wheel brake is applied with a preset additional braking torque greater than the basic braking torque. If it is thus determined that the brake pedal sensor device is not functioning, the at least one wheel brake is initially applied with the basic braking torque. If the accelerator pedal is subsequently actuated, after the actuation of the accelerator pedal, the at least one wheel brake is applied with the additional braking torque instead of reapplying with the basic braking torque. Because the additional braking torque is greater than the basic braking torque, a stronger vehicle braking deceleration is now achieved than when previously applied with the basic braking torque.

[0042] This embodiment is based on the understanding that the driver should clearly understand that further acceleration of the vehicle is practically meaningless in the current situation. Since the driver has already confirmed that he can further accelerate the vehicle, for example, by forcefully manipulating the accelerator pedal, and now understands that this is practically pointless, an additional braking torque, increased compared to the basic braking torque, is preset. Once the accelerator pedal is no longer manipulated, it automatically and amplifies the braking of the vehicle. Thus, after, for example, a previous re-acceleration using measured acceleration information, the vehicle can be decelerated more forcefully. Through the increased additional braking torque compared to the basic braking torque (applying this additional braking torque to the brakes of at least one wheel), the driver should clearly understand that the braking system is no longer functioning fully properly, and that the driver should, if possible, bring the vehicle to a standstill.

[0043] Furthermore, one embodiment is configured such that if the accelerator pedal is re-operated and the detected accelerator pedal operation information upon re-operation is greater than or equal to the accelerator pedal operation limit, then repetitive acceleration information is determined by applying a repetitive acceleration determination criterion to the detected accelerator pedal operation information. The repetitive acceleration information describes the vehicle's acceleration as being less than the acceleration measured when the fault condition acceleration determination criterion is applied. The drive unit is thus operated such that the vehicle accelerates according to the repetitive acceleration information. Therefore, the propulsion power possible under further acceleration desire by the driver is reduced compared to the propulsion power still possible under the first acceleration desire. This reduction always occurs when the driver has operated the brake pedal once after confirming that the brake pedal sensor device is not functioning and then operates the accelerator pedal a second time. The repetitive acceleration determination criterion is a rule or algorithm applied during the second operation of the accelerator pedal.

[0044] This achieves the goal of allowing the vehicle to accelerate at increasingly smaller rates with each further application of the accelerator pedal. This informs the driver that further acceleration is practically pointless due to a malfunction in the vehicle. However, it still allows the driver to maneuver the vehicle, for example, to a parking spot or the edge of the road, without being forced to stop beforehand.

[0045] Alternatively, in one embodiment, a withdrawal speed value can be measured, describing the speed at which the accelerator pedal is withdrawn. This allows, for example, determining at what time the driver releases his foot from the accelerator pedal and by how much of the accelerator pedal travel. This can be detected using an accelerator pedal sensor device. If the withdrawal speed value is greater than a withdrawal speed limit, a withdrawal braking torque greater than the basic braking torque is applied to the at least one wheel brake. This achieves a greater deceleration of the vehicle when the accelerator pedal is quickly released than that set by the basic braking torque without accelerator pedal operation. In other words, if the driver releases his foot from the accelerator pedal quickly for a short period, the driver can express braking desire without operating the brake pedal. In the event that the brake pedal sensor device is inoperable, the withdrawal speed of the accelerator pedal withdrawal can cause the vehicle to stop more quickly, allowing the driver to continue operating the braking system even though the brake pedal sensor device is inoperable.

[0046] It can also be configured such that, if the electric parking brake of the vehicle is activated, at least one wheel brake that is not an electric parking brake is additionally applied with a braking torque greater than the basic braking torque associated with the parking brake. This additional braking torque can, for example, brake the vehicle to a standstill. By operating the electric parking brake, the vehicle can still be brought to a standstill even though the brake pedal sensor device is not functioning and therefore the brake pedal is not operated.

[0047] In a preferred embodiment, the motor vehicle is equipped with an ambient environment sensor device. The ambient environment sensor device (e.g., configured as a front camera of the motor vehicle) detects at least one ambient environment in the area in front of the motor vehicle. Therefore, the ambient environment sensor device detects at least one sensor data describing the ambient environment in the area in front of the motor vehicle. The sensor data is, for example, camera data, i.e., static and / or moving image data.

[0048] Obstacle recognition criteria are applied to detect obstacles in the surrounding environment of an area ahead based on sensor data. Obstacles can be, for example, buildings, road infrastructure elements such as traffic signs and / or traffic lights, other road users and / or pedestrians. The obstacle recognition criteria include rules and / or algorithms by which obstacles in the sensor data can be detected and identified. For this purpose, image processing methods can be applied, for example, to the obstacle recognition criteria.

[0049] If an obstacle has been detected, the at least one wheel brake is applied with an obstacle-related braking torque greater than the basic braking torque. Therefore, if an obstacle is detected in the area ahead, a higher vehicle deceleration is adjusted compared to the deceleration adjusted when essentially no obstacle is detected. This allows, for example, emergency braking to a complete stop, i.e., an immediate emergency stop of the vehicle can be performed due to obstacle detection. In this case, the obstacle-related braking torque is, for example, the maximum braking torque of the vehicle. Therefore, the braking torque can be preset according to the situation, thereby responding to a malfunction of the brake pedal sensor device as needed.

[0050] A second aspect of the invention relates to a method for notifying a driver of a motor vehicle of a malfunction associated with the vehicle's energy supply. The motor vehicle has: an energy supply; a braking system having a brake pedal and at least one wheel brake associated with one wheel of the vehicle, the wheel brake being operable with respect to manual operation of the brake pedal; and a drive system having a brake pedal and a drive mechanism for longitudinal control of the motor vehicle, the drive mechanism being operable with respect to manual operation of an accelerator pedal. The method comprises the steps of: confirming a malfunction associated with the energy supply, wherein, despite the malfunction being confirmed, the at least one wheel brake and the drive mechanism are still operable with respect to corresponding manual operation; and if the brake pedal of the motor vehicle is operated and then the accelerator pedal is operated, acceleration of the motor vehicle is permitted only after a preset waiting period, with respect to manual operation of the accelerator pedal.

[0051] Regarding the second aspect, in an advantageous embodiment, the drive unit and / or the at least one wheel brake may be manipulated such that the current propulsion power of the motor vehicle is reduced after a fault associated with the energy supply unit is confirmed.

[0052] Furthermore, regarding the second aspect, it can be configured such that the at least one wheel brake is an electronic parking brake, which is brought to a persistently active state after a fault associated with the energy supply unit is confirmed, wherein the motor vehicle can continue to be driven by actuation of the accelerator pedal despite the electronic parking brake being in a persistently active state.

[0053] A third aspect of the invention relates to a method for notifying the driver of a motor vehicle of a malfunctioning brake pedal sensor device. The motor vehicle has a braking system comprising: a brake pedal; at least one wheel brake associated with one wheel of the motor vehicle, the wheel brake being electronically operable in consideration of manual operation of the brake pedal; and a brake pedal sensor device. The motor vehicle further has a drive system including: a brake pedal; a drive mechanism for longitudinal control of the motor vehicle, the drive mechanism being electronically operable in consideration of manual operation of the accelerator pedal; and an accelerator pedal sensor device. A malfunction associated with the motor vehicle's braking system is confirmed. Due to the confirmed malfunction, the brake pedal sensor device is inoperable.

[0054] The method includes: applying a preset basic braking torque to the at least one wheel brake; if the accelerator pedal is actuated, detecting accelerator pedal actuation information using the accelerator pedal sensor device, the accelerator pedal actuation information describing the actuation travel of the accelerator pedal through the actuation; if the detected accelerator pedal actuation information is less than the accelerator pedal actuation limit, applying a special case braking torque to the at least one wheel brake, the special case braking torque being less than the basic braking torque; if the detected accelerator pedal actuation information is greater than or equal to the accelerator pedal actuation limit, determining acceleration information describing the acceleration of the vehicle by applying a fault condition acceleration determination criterion to the detected accelerator pedal actuation information, and maneuvering the drive system such that the vehicle accelerates according to the acceleration information.

[0055] A third embodiment is configured such that if the detected accelerator pedal manipulation information is less than the accelerator pedal manipulation limit value, then the vehicle is not accelerated, taking into account the detected accelerator pedal manipulation information.

[0056] Furthermore, the measured acceleration information may be less than the typical acceleration information, which is measured when the normal acceleration determination standard, which differs from the fault condition acceleration determination standard and is applied when the fault is not confirmed, is applied to the detected accelerator pedal operation information.

[0057] Furthermore, in a third embodiment, the at least one wheel brake may be configured to be applied with a preset additional braking torque greater than the basic braking torque after the accelerator pedal is actuated.

[0058] Furthermore, if the accelerator pedal is re-operated and the detected accelerator pedal operation information is greater than or equal to the accelerator pedal operation limit value, then repetitive acceleration information is measured when the repetitive acceleration determination criterion is applied to the detected accelerator pedal operation information. The repetitive acceleration information describes the acceleration of the motor vehicle as being less than the acceleration measured when the fault condition acceleration determination criterion is applied, and the drive unit is manipulated such that the motor vehicle accelerates according to the repetitive acceleration information.

[0059] According to an embodiment of the third aspect, a retraction speed value can be measured, the retraction speed value describing the speed at which the accelerator pedal is retracted, and if the retraction speed value is greater than a retraction speed limit value, then the at least one wheel brake is applied with a retraction braking torque greater than the basic braking torque.

[0060] The motor vehicle may have an ambient environment sensor device and use the ambient environment sensor device to detect sensor data describing at least one ambient environment in front of the motor vehicle, wherein obstacles in the ambient environment in the front area are determined when an obstacle identification criterion is applied to the detected sensor data, and if the obstacle is determined, the at least one wheel brake is applied with an obstacle-related braking torque greater than the basic braking torque.

[0061] Another aspect of the invention relates to a motor vehicle according to the invention. The motor vehicle is configured to perform the methods described above according to one or more of the other aspects, embodiments, and / or combinations thereof. The embodiments described in conjunction with the methods according to the invention and their advantages are applicable wherever appropriate to the motor vehicle according to the invention. The motor vehicle is, for example, a passenger car, a freight car, a bus, or a motorcycle.

[0062] The present invention also includes combinations of features of the described embodiments. Attached Figure Description

[0063] Embodiments of the present invention are described below. Therefore:

[0064] Figure 1 A schematic diagram of a motor vehicle is shown;

[0065] Figure 2 A schematic diagram of a signal flow diagram illustrating a method for notifying the driver of a motor vehicle of a fault associated with the vehicle's braking system;

[0066] Figure 3 It is a schematic diagram showing the relationship between brake pedal operation information and braking torque information;

[0067] Figure 4 The diagram illustrates the following: Figure 2 Signal flow graph of other method steps of the method;

[0068] Figure 5 A schematic diagram of a signal flow diagram illustrating a method for notifying the driver of a motor vehicle of a malfunction associated with the vehicle's energy supply components;

[0069] Figure 6 A schematic diagram of a signal flow diagram illustrating a method for notifying a driver of a motor vehicle of a brake pedal sensor device that is not functioning.

[0070] Figure 7 A schematic diagram illustrating the relationship between accelerator pedal operation information and braking torque information or acceleration information.

[0071] Figure 8 A signal flow diagram illustrating the steps of a method for determining repetitive acceleration information is provided.

[0072] Figure 9 A signal flow diagram illustrating the steps of a method for determining the withdrawing braking torque is provided below.

[0073] Figure 10 A signal flow diagram illustrating the steps of a method for determining braking torque in obstacle situations is provided.

[0074] Figure 11 A schematic diagram illustrating the relationship between the energy content of a motor vehicle's energy supply components and its driving power or braking torque information. Detailed Implementation

[0075] The embodiments described below are preferred embodiments of the invention. In these embodiments, the described components are individual features of the invention that should be considered independently of each other, and these features also independently extend the invention and therefore should be considered individually or in combinations different from those shown as part of the invention. Furthermore, the described embodiments can also be supplemented by other features of the invention already described.

[0076] In the accompanying drawings, elements with the same function are given the same reference numerals.

[0077] exist Figure 1 The diagram depicts a motor vehicle 1. The motor vehicle 1 has a braking system including a brake pedal 2. The brake pedal 2 can be manually operated by the driver of the motor vehicle 1. The motor vehicle 1 has four wheels 3, more specifically two front wheels and two rear wheels. Each of the wheels 3 of the motor vehicle 1 is associated with at least one wheel brake 4 of the braking system. Preferably, each of the two rear wheels 3 is associated with two wheel brakes 4, more specifically, a hydraulic brake and an electronic parking brake, respectively. The motor vehicle 1 has at least one wheel brake 4, wherein, in the example shown here, the motor vehicle has a total of six wheel brakes 4. Taking into account the manual operation of the brake pedal 2, the corresponding wheel brakes 4 can be electronically operated. The braking system of the motor vehicle 1 is therefore a brake-by-wire braking system.

[0078] The braking system is associated with a control device 5, which is configured to apply a preset braking torque to each wheel brake 4. To detect the operation of the brake pedal 2, the braking system has a brake pedal sensor device 6. The control device 5 is provided with data from the brake pedal sensor device 6. The control device 5 is configured to operate the wheel brakes 4. The control device 5 may be a computing device and, in particular, has a processor.

[0079] Motor vehicle 1 has an accelerator pedal 7. Strictly speaking, motor vehicle 1 has a drive system with the accelerator pedal 7 and a drive device 8 for longitudinal control of motor vehicle 1. Taking into account the manual operation of the accelerator pedal 7, the drive device 8 can be electronically controlled. Motor vehicle 1 therefore has a drive-by-wire drive system.

[0080] The drive system includes a drive control device 9 configured to operate the drive device 8. The drive control device 9 is configured to evaluate the operation of the accelerator pedal 7 and operate the drive device 8 while taking into account the manual operation of the accelerator pedal 7. The drive device 8 is, for example, an electric motor or an internal combustion engine.

[0081] The drive system also includes an accelerator pedal sensor device 10, which is configured to detect operation of the accelerator pedal 7 and transmit the corresponding detected data to the drive control device 9, thereby enabling the drive control device to electronically operate the drive device 8 while taking into account manual operation of the accelerator pedal 7.

[0082] Motor vehicle 1 has an energy supply unit 11. The energy supply unit 11 is configured to supply electrical energy to at least the braking system and the drive system. If motor vehicle 1 is an electric vehicle or a hybrid vehicle, the energy supply unit 11 is, for example, a battery, such as a high-voltage battery.

[0083] The motor vehicle 1 has an ambient environment sensor device 39, by means of which at least one ambient environment 40 in the area in front of the motor vehicle 1 can be detected.

[0084] exist Figure 2 The document describes method steps for notifying the driver of motor vehicle 1 of a fault 12 associated with the braking system of motor vehicle 1. In method step S1, the existence of fault 12 associated with the braking system of motor vehicle 1 is confirmed. Despite the confirmation of fault 12, the brake pedal sensor device 6 remains functional, the at least one wheel brake 4 remains operable, and the brake pedal 2 remains operable. For example, fault 12 is a leak of hydraulic fluid in the hydraulic brake 4, which is the wheel brake 4. Despite this leak, at least one wheel brake 4 associated with the wheel 3 of motor vehicle 1, such as an electric parking brake or other hydraulic brake unaffected by the leak, remains operable.

[0085] In method step S2, brake pedal operation information 13 can be detected using brake pedal sensor device 6. Brake pedal operation information 13 describes the operation distance traveled by the operation of brake pedal 2. Finally, brake pedal operation information 13 describes how strongly the driver operates brake pedal 2.

[0086] In method step S3, the fault condition braking torque determination criterion 14 can be applied to the detected brake pedal operation information 13, wherein braking torque information 15 is measured. Braking torque information 15 describes the braking torque for the at least one wheel brake 4 of the motor vehicle 1. In another method step S4, the at least one wheel brake 4 can be applied with the braking torque described by the measured braking torque information 15. Method steps S3 and S4 are preferably performed using the control device 5 of the braking system.

[0087] exist Figure 3 The diagram shows brake pedal operation information 13 plotted on the x-axis and braking torque information 15 plotted on the y-axis, which is perpendicular to the x-axis. When the fault condition braking torque determination criterion 14 is applied in method step S3, the braking torque information 15, which is preset as curve 14 based on a solid line, is associated with the corresponding brake pedal operation information 13. In contrast, the direction of the braking torque information 15 is also depicted as a solid line as curve 17, which is measured when the normal condition braking torque determination criterion 17 is applied. If no fault 12 is confirmed, the normal condition braking torque determination criterion is always applied. These two criteria are different from each other.

[0088] The braking torque information 15 measured when applying the fault condition braking torque determination criterion 14 is characterized in that if the traveled actuation stroke is less than at least one-third 19 of the maximum actuation stroke 16 that can be traveled when the brake pedal 2 is actuated, then the determined braking torque is less than one-third 19 of the typical braking torque. The typical braking torque is the braking torque measured when the normal condition braking torque determination criterion 17 is applied to the detected braking torque information 15. In the first one-third 19 of the maximum actuation stroke 16, which is the brake pedal actuation information 13, the corresponding measured braking torque information 15 is therefore at most one-third 19 of the corresponding value of the curve plotted when the normal condition braking torque determination criterion 17 is applied.

[0089] If the brake pedal 2 is actuated through the maximum actuation stroke 16, the measured braking torque information 15 adopts the maximum braking torque 18. The maximum braking torque 18 is the maximum braking torque at which the at least one wheel brake 4 can be applied. At least at this point, i.e., at the maximum actuation stroke 16 with the maximum braking torque 18, the two curves depicted here intersect, more specifically, curve 14 determined by applying the fault condition braking torque determination criterion 14 and curve 17 determined by applying the normal condition braking torque determination criterion 17 intersect.

[0090] In the second or third third of the brake pedal operation information 13, the measured braking torque information 15 is preferably increased, wherein, for example, initially, a weaker increase in the braking torque information 15 can be set in the second third compared to the third third.

[0091] exist Figure 3 In the diagram, the alternative trajectory of the measured braking torque information 15 is depicted as curve 14′ using a dashed line. This trajectory is measured using an alternative fault condition braking torque determination criterion 14′, which differs from the fault condition braking torque determination criterion 14. In the example depicted for curve 14′, the measured braking torque information 15 is zero in the first third 19 of the maximum operating travel 16, meaning that despite brake pedal operation, no braking of the vehicle 1 occurs in this region. For example, in the second and third thirds of the maximum operating travel 16, a steeper increase in the measured braking torque information 15 is set, where the maximum braking torque 18 is re-reached at the maximum operating travel 16.

[0092] exist Figure 4 Further method steps S5 to S8 are described below. In method step S5, in particular, the operating speed value 20 is measured. For this purpose, for example, a corresponding time evaluation can be performed on the brake pedal operating information 13 using the control device 5. The operating speed value 20 describes the operating speed of the brake pedal 2. Then, in method step S6, it can be checked whether the measured operating speed value 20 is greater than the operating speed limit value 21. If this is the case, then in method step S7, the normal braking torque determination criterion 17 can be applied to the detected brake pedal operating information 13 so that the braking torque information 15 is obtained and then the at least one wheel brake 4 is applied accordingly according to method step S4. Alternatively, method step S8 can be performed, according to the method steps, applying the intermediate braking torque determination criterion 22 to the detected brake pedal operating information 13, wherein the braking torque information 15 is measured. The intermediate-condition braking torque determination criterion 22 associates a braking torque information 15 with each brake pedal operation information 13. This braking torque information can alternatively be referred to as the intermediate-condition braking torque determination criterion and is greater than the braking torque information 15 measured when the fault-condition braking torque determination criterion 14 is applied. Then, method step S4 can be repeated, i.e., the at least one wheel brake 4 is applied according to the braking torque information 15.

[0093] exist Figure 5The diagram illustrates a possible method, either as an adjunct or alternative to the above method, in which a fault 12' associated with the energy supply unit 11 of the motor vehicle 1 is identified in method step S1'. Despite the identification of the fault 12' associated with the energy supply unit 11, the at least one wheel brake 4 and drive unit 8 can still be operated, taking into account the corresponding manual operation of the pedals. That is, not only the brake pedal 2 but also the brake pedal sensor device 6, as well as the accelerator pedal 7 and accelerator pedal sensor device 10, continue to function. However, a fault 12' exists involving at least the braking system and also the current or future energy supply unit 11 of the electrically powered drive system.

[0094] In method step S9, the operation of the brake pedal 2 can be observed. Then, preferably in method step S10, the accelerator pedal 7 is operated, and then, particularly in method step S11, a waiting period 23 is waited. The waiting period 23 can alternatively be called the dead time. Only when the waiting period 23 has been waited, particularly in method step S12, is the vehicle 1 accelerated by means of the drive device 8, taking into account the manual operation of the accelerator pedal 7. Thus, despite the operation of the accelerator pedal 7, a permissible delay occurs in the acceleration of the vehicle 1. After method step S1′, that is, after confirming the fault 12′ associated with the energy supply unit 11 or after method step S12, the current propulsion power 24 is reduced. This is achieved by correspondingly operating the drive device 8 and / or at least one wheel brake 4. Ultimately, the speed of the vehicle 1 is thus reduced.

[0095] Following method steps S1′ and / or S12, it may be further configured in method step S14 to place the electronic parking brake, which serves as the wheel brake 4, in a persistently active state. The electronic parking brake is preferably located on one of the rear wheels 3 of the vehicle 1. This results in continued braking by means of the persistently active parking brake in the event of a failure of the energy supply 11, because the parking brake remains active despite the failure of, for example, the drive unit 8 and other components of the braking system. Thus, the vehicle 1 can be braked to a standstill, for example, after the energy supply 11 has indeed failed.

[0096] exist Figure 6The following describes alternative or alternative method steps S1′′ and S15 to S20. Here, in method step S1′′, a fault 12′′ is identified, due to which the brake pedal sensor device 6 cannot function. In the subsequent method step S15, the at least one wheel brake 4 is applied with a preset basic braking torque 25. If the accelerator pedal 7 is now actuated, for example by the driver, accelerator pedal actuation information 26 is detected in method step S16 by means of the accelerator pedal sensor device 10. Accelerator pedal actuation information 26 describes the actuation travel of the accelerator pedal 7 by actuation. Then, in method step S17, it is checked whether the detected accelerator pedal actuation information 26 is less than the accelerator pedal actuation limit value 27. If this is the case, it is preferable to apply the at least one wheel brake 4 with a special case braking torque 28 less than the basic braking torque 25 in method step S18. Therefore, weakened braking of the vehicle 1 occurs. However, at the same time, the vehicle 1 does not accelerate further because, in this case, the vehicle 1 is not accelerated considering the detected accelerator pedal actuation information 26.

[0097] If the detected accelerator pedal operation information 26 is greater than or equal to the accelerator pedal operation limit value 27, then in method step S19, the fault condition acceleration determination criterion 29 can be applied to the detected accelerator pedal operation information 26. Here, acceleration information 30 is measured. This describes the acceleration of the vehicle 1. In method step S20, the drive device 8 is specifically manipulated such that the vehicle 1 is accelerated according to the acceleration information 30.

[0098] exist Figure 7 A graph is depicted in which accelerator pedal operation information 26 is given on the x-axis, braking torque information 15 is given on the downward-pointing y-axis, and acceleration information 30 is given on the upward-pointing y-axis. The trajectory of accelerator pedal operation information 26 under the preset braking torque information 15, determined by the application of fault condition acceleration determination standard 29, is depicted here as curve 29 (solid line). Under fault-free conditions, when applying normal condition acceleration determination standard 31, the acceleration of vehicle 1 increases, i.e., the acceleration information 30 increases with the increase of accelerator pedal operation information 26, as shown by curve 31.

[0099] When applying the fault condition acceleration determination criterion 29, the at least one wheel brake 4 is first applied purely with a basic braking torque 25 if the accelerator pedal 7 has not yet been actuated. Once the accelerator pedal 7 is actuated, the vehicle 1 is not accelerated until the accelerator pedal actuation limit 27 is reached; instead, the vehicle is further braked, i.e., a predetermined braking torque information 15 greater than zero is preset. This corresponds to the corresponding special case braking torque 28. The vehicle 1 is only accelerated when the accelerator pedal actuation information 26 is greater than or equal to the accelerator pedal actuation limit 27, wherein the acceleration is less than the acceleration when applying the normal condition acceleration determination criterion 31 with the same accelerator pedal actuation information 26.

[0100] exist Figure 7 Furthermore, a pre-accelerator pedal control limit 32 is described, which is located before the accelerator pedal control limit 27. After reaching this pre-accelerator pedal control limit, despite a large accelerator pedal control information 26, braking is not preset, i.e., neither a braking torque information 15 greater than zero nor an acceleration information 30 greater than zero is preset. Therefore, a free travel can be set between the pre-accelerator pedal control limit 32 and the accelerator pedal control limit 27.

[0101] If, after actuating the accelerator pedal 7, neither the brake pedal 2 nor the accelerator pedal 7 is actuated, the basic braking torque 25 increases to an additional braking torque 33. Therefore, after the accelerator pedal 7 is actuated, the at least one wheel brake 4 is applied with a preset additional braking torque 33, which is greater than the basic braking torque 25. The corresponding trajectory when the accelerator pedal 7 is then actuated again is depicted as a dashed line as curve 29′, which is determined when applying the alternative design fault condition acceleration determination criterion 29′. If the accelerator pedal actuation information 26 is now reconfirmed to be greater than or equal to the accelerator pedal actuation limit value 27, then, when applying the repetitive condition acceleration determination criterion 34 to the detected accelerator pedal actuation information 26, the acceleration information 30 is less than the acceleration measured when applying the fault condition acceleration determination criterion 29′.

[0102] exist Figure 8 Detailed description from Figure 7The single method steps have become clear. In method step S21, the accelerator pedal 7 is operated again after the first operation. Here, the re-detected accelerator pedal operation information 26′ is measured by means of the accelerator pedal sensor device 10. Then, in method step S22, it is preferably checked whether the re-detected accelerator pedal operation information 26′ is less than the accelerator pedal operation limit value 27. If this is the case, the special case braking torque 28, which is less than the basic braking torque 25 and the additional braking torque 33, can be measured in method step S23.

[0103] If, in method step S22, it is confirmed that the re-detected accelerator pedal operation information 26′ is greater than or equal to the accelerator pedal operation limit value 27, then in method step S24, the repetitive acceleration determination criterion 34 can be applied to the re-detected accelerator pedal operation information 26′, and the repetitive acceleration information 35 can be measured thereon. Subsequently, preferably in method step S25, the acceleration of the vehicle 1, i.e., the corresponding control of the drive device 8, is performed based on the repetitive acceleration information 35. In this case, the repetitive acceleration information 35 replaces the acceleration information 30 determined when the accelerator pedal 7 is first operated. An alternative expression for the repetitive acceleration information 35 can be referred to as the acceleration information 30 when the accelerator pedal 7 is operated a second time.

[0104] exist Figure 9 Method steps S26 to S28 are described below. These steps may follow method step S20 directly, or they may follow method steps S23 or S25. In method step S26, in particular, a withdrawal speed value 36 is measured, which specifically describes the speed at which the accelerator pedal 7 is withdrawn. In method step S27, it can be checked whether the withdrawal speed value 36 is greater than the withdrawal speed limit value 37. If this is the case, then in method step S28, the at least one wheel brake 4 is preferably applied with a withdrawal braking torque 38 greater than the basic braking torque 25. Thus, enhanced braking is achieved, i.e., the applied braking torque is increased according to the braking torque information 15. If the check is negative in method step S27, then the method may, for example, be terminated, or method step S26 may be re-executed.

[0105] exist Figure 10Method steps S29 to S32 are described, which may follow, for example, method steps S20, S23, S25 and / or S28. According to method step S29, sensor data 41 is detected by means of the ambient environment sensor device 39 of the vehicle 1, the sensor data describing at least the ambient environment 40 of the area in front of the vehicle 1. In method step S30, obstacle identification criteria 42 are then preferably applied to the detected sensor data 41. In method step S31, obstacles 43 in the ambient environment 40 of the area in front can then be determined and identified. If, for example, no obstacle 43 is determined in method step S31, method step S29 can be repeated, or alternatively, the method can be terminated. If an obstacle 43 is determined, in method step S32, at least one wheel brake 4 can be applied with an obstacle-condition braking torque 44, which is greater than the basic braking torque 25. Therefore, in the presence of an obstacle, stronger braking of the vehicle 1 is achieved regardless of the operation of the accelerator pedal 7.

[0106] exist Figure 11 The diagram shows a graph in which the energy content 45 of the energy supply component 11 (e.g., the high-voltage battery of vehicle 1) is depicted on the x-axis. On the y-axis, not only the driving power 46 but also the braking torque information 15 is depicted. Furthermore, the driving power 46 is depicted as a solid line relating to the energy content 45, where this line has three regions. The driving power 46 initially increases linearly in a first region between zero energy content 45 and a maximum energy content 47, then extends constantly in a second region, and then abruptly increases to the level of a third region. The second region describes sufficient remaining energy 48 to supply energy to the braking and drive systems of vehicle 1. A critical energy region is located in the first region, referred to as the critical state 49. The maximum energy content 47 is provided in the third region. It is clear that a large driving power 46 is always present in the region with sufficient remaining energy 48 and in the adjacent region with the maximum energy content 47. However, the driving power continuously decreases in the first region of the critical state 49. From the beginning of the first region, the electronic parking brake can, for example, switch to a persistently active state, in which the acceleration of the vehicle 1 can initially continue because, for example, energy can continue to be supplied to the drive unit 8 even though the energy supply unit 11 is in a critical state 49. However, once the energy content 45 reaches zero, as depicted here by dashed lines, braking torque information 15 is obtained from the parking brake in the active state, thereby braking the vehicle 1.

[0107] In general, these examples illustrate a method for operating a braking system at the backup level. To enable tactile feedback to the brake pedal 2, which lacks its own feedback actuator, a relatively wide free travel is set. That is, in fault conditions, i.e., when fault 12 occurs, the braking deceleration is adjusted to a lower level compared to the fault-free condition, with the same pedal operation of brake pedal 2. This is achieved by applying fault-condition braking torque determination criterion 14 and braking torque information 15 instead of the normal condition braking torque determination criterion 17. Figure 3 This is achieved by selectively reducing the first third 19 of the maximum operating travel 16. This approach partially corresponds to a failure mode or failure diagram of the brake regulation system, where, in the event of an electronic failure, the driver must first experience a free travel before being able to apply the brakes using the hydraulic backup level. Advantageously, it is now possible to achieve vehicle rolling deceleration even with maximum pedal operation, i.e., upon reaching the maximum operating travel 16, i.e., then preset the maximum braking torque 18 for applying the at least one wheel brake 4. Thus, for example, emergency braking situations and unnecessarily long braking travel can be prevented. It is not important here whether the critical failure state exists due to a fault 12 in the driver's brake detection, a fault in the brake actuator, or a fault in the wheel brake 4 itself.

[0108] In an online-controlled braking system, a fault 12' in the energy supply component 11 also leads to at least partial failure of the braking system. Here, the complete loss and degradation of the energy supply component 11 (which can no longer achieve normal braking) are particularly critical. In these cases, early intervention is necessary. Advantageously, by skillfully monitoring the energy supply component 11, for example by measuring the individual cell voltages in the battery that serves as the energy supply component 11, it is possible to identify the complete failure of the energy supply component 11 with a small lead time, for example, one minute. If the energy supply 11 is particularly critical, additional upgrades can be taken to prevent, for example, unbraked, uncontrollable vehicle 1: reducing propulsion power 24; reducing speed through targeted braking intervention; generating sustained braking intervention that is maintained even in the event of voltage supply failure, i.e., energy supply 11 failure (e.g., by employing an electric parking brake or locking the braking pressure in wheel brake 4 when the valve is closed without current); indicating a fault 12' in the energy supply 11 by means that, after braking, propulsion can only be adjusted with a delay, i.e., by a dead time in the form of a preset waiting period 23 when the brake is released and the accelerator pedal 7 is operated. In the event of a fault, the possibility of the drive unit 8 and the at least one wheel brake 4 operating simultaneously is very limited. Thus, in the event of a sudden voltage drop, i.e., in the event of complete failure of the energy supply 11, the braking force on the wheel where the at least one activated wheel brake 4 is located is maintained. The failure of the energy supply 11 is particularly noteworthy if the steering system of vehicle 1 also ceases to function simultaneously. For example, this is the case in a vehicle with steer-by-wire, where, in the event of a complete failure of the energy supply component 11, further steering of the vehicle, i.e., lateral guidance of vehicle 1, can no longer be controlled. Therefore, it is important to stop vehicle 1 promptly in this situation. Thus, it is meaningful to purposefully bring vehicle 1 to a standstill in this condition.

[0109] While a failure of the brake pedal sensor device 6 is unlikely, as redundant voltage supply, signal detection, and evaluation are typically provided for the electric brake pedal 2, it is still conceivable that the brake pedal sensor device 6, and therefore the sensing of the driver's braking expectation, might fail. Therefore, an additional backup layer for detecting the driver's braking expectation is meaningful. If we now assume a complete failure in detecting the driver's braking expectation via the brake pedal 2, minimal deceleration can be achieved by the braking system without actuating the accelerator pedal 7, by using a basic braking torque 25 and applying the basic braking torque to the at least one wheel brake 4. If the driver then actuates the accelerator pedal 7, this results in a reduction in braking deceleration under minor actuation, i.e., applying a special braking torque 28 less than the basic braking torque 25 to the at least one wheel brake 4. However, under stronger actuation, the vehicle 1 then accelerates, i.e., the failure-condition acceleration determination criterion 29 is applied and acceleration information 30 is measured. Due to the reduced braking performance, acceleration or propulsion may also decrease. If the driver of vehicle 1 accepts this type of operation of vehicle 1, the deceleration can be increased after the first acceleration, i.e., the basic braking torque 25, or more precisely, the additional braking torque 33, thereby presenting a significant deceleration for the driver. When the accelerator pedal 7 is released particularly quickly, a greater deceleration can also be adjusted, that is, the retraction braking torque 38 can be selected and braking can be performed using the retraction braking torque 38. If the driver operates the electric parking brake when the brake pedal 2 fails, the deceleration can also be increased. Ultimately, this can occur up to the full deceleration. If an obstacle 43 is identified in the area ahead via an ambient detection device, such as a front radar or camera, i.e., by means of an ambient sensor device 39, a higher deceleration can also be adjusted, i.e., applying the obstacle braking torque 44 to the at least one wheel brake 4.

[0110] List of reference numerals

[0111] 1 Motor vehicles

[0112] 2. Brake pedal

[0113] 3 wheels

[0114] 4. Wheel brakes

[0115] 5. Control equipment

[0116] 6. Brake pedal sensor device

[0117] 7. Accelerator pedal

[0118] 8. Drive devices

[0119] 9. Drive control equipment

[0120] 10 Accelerator pedal sensor device

[0121] 11 Energy supply components

[0122] Faults at 12, 12′, and 12′′

[0123] 13 Brake Pedal Operation Information

[0124] 14. Criteria for Determining Braking Torque in Fault Conditions

[0125] 15. Braking torque information

[0126] 16 Maximum operating travel

[0127] 17. Standards for determining braking torque under normal conditions

[0128] 18 Maximum braking torque

[0129] 19 The first third

[0130] 20 Maneuvering speed value

[0131] 21. Operating speed limit

[0132] 22. Criteria for Determining Braking Torque in Intermediate Situations

[0133] 23 Waiting time

[0134] 24 Propulsion Power

[0135] 25. Basic braking torque

[0136] 26, 26' Accelerator pedal operation information

[0137] 27 Accelerator pedal handling limits

[0138] 28 Braking torque under special circumstances

[0139] 29. Acceleration Determination Criteria for Fault Conditions

[0140] 30 Acceleration Information

[0141] 31. Standards for Determining Acceleration under Normal Conditions

[0142] 32 Pre-accelerator pedal control limits

[0143] 33 Additional braking torque

[0144] 34. Criteria for Determining Acceleration in Repeated Cases

[0145] 35. Acceleration information under repeated conditions

[0146] 36. Retreat speed value

[0147] 37. Maximum pullback speed

[0148] 38. Retraction braking torque

[0149] 39. Ambient environment sensor device

[0150] 40 Surrounding environment

[0151] 41 Sensor Data

[0152] 42 Obstacle Recognition Standards

[0153] 43 Obstacles

[0154] 44. Braking torque under obstacle conditions

[0155] 45 Energy content

[0156] 46. ​​Driving power

[0157] 47 Maximum Energy Content

[0158] 48 Remaining Energy

[0159] 49 Critical State

[0160] S1-S32 Method Steps

[0161] S1′, S1′′ Method steps.

Claims

1. A method for notifying a driver of a motor vehicle (1) of a first fault (12) associated with the braking system of the motor vehicle (1), wherein, The braking system includes: a brake pedal (2); at least one wheel brake (4) associated with a wheel (3) of the motor vehicle (1), the wheel brake (4) being electronically operable while taking into account manual operation of the brake pedal (2); and a brake pedal sensor device (6), wherein the method includes the following steps: - A first fault (12) associated with the braking system of the motor vehicle (1) is confirmed, wherein, despite the confirmation of the first fault (12), the brake pedal sensor device (6) remains functional, the at least one wheel brake (4) remains operable, and the brake pedal (2) remains operable; and -If the brake pedal (2) is operated, • Brake pedal operation information (13) is detected by means of the brake pedal sensor device (6), which describes the operation stroke of the brake pedal (2) by operation. • Braking torque information (15) is measured when the fault condition braking torque determination criterion (14) is applied to the detected brake pedal operation information (13), the braking torque information (15) describing the braking torque for the at least one wheel brake (4), wherein if the traveled is less than at least one-third (19) of the maximum traveled when the brake pedal (2) is operated, the measured braking torque is less than one-third (19) of a typical braking torque, which is measured when the normal condition braking torque determination criterion (17), which is different from the fault condition braking torque determination criterion (14) and is applied when the first fault (12) is not confirmed, is applied to the detected brake pedal operation information (13), but if the maximum traveled (16) has been traveled, the measured braking torque information (15) describes a maximum braking torque (18) that the at least one wheel brake (4) can be loaded with; and • Apply the braking torque described by the measured braking torque information (15) to the at least one wheel brake (4).

2. The method according to claim 1, wherein, If the traveled is less than one-third (19) of the maximum travel (16), the measured braking torque information (15) is zero.

3. The method according to any one of the preceding claims, wherein, The operating speed value (20) is determined, which describes the operating speed of the brake pedal (2), and if the operating speed value (20) is greater than the operating speed limit value (21), the normal braking torque determination standard (17) is applied.

4. The method according to any one of claims 1 or 2, wherein, A control speed value (20) is determined, which describes the speed at which the brake pedal (2) is operated, and if the control speed value (20) is greater than the control speed limit value (21), an intermediate-condition braking torque determination criterion (22) is applied, which associates an intermediate-condition braking torque information with each brake pedal operation information (13), and the intermediate-condition braking torque information is greater than the braking torque information (15) determined when the fault condition braking torque determination criterion (14) is applied.

5. The method according to claim 1 or 2, wherein, The motor vehicle (1) has an energy supply unit (11) and a drive system, the drive system having an accelerator pedal (7) and a drive device (8) for longitudinal control of the motor vehicle (1), the drive device (8) being electronically controllable while taking into account manual operation of the accelerator pedal (7), wherein, - A second fault (12') associated with the energy supply unit (11) was confirmed, wherein, despite the confirmation of the second fault (12') associated with the energy supply unit (11), the at least one wheel brake (4) and the drive device (8) remain operable with respect to the corresponding manual operation; and - If the brake pedal (2) of the motor vehicle (1) is operated and then the accelerator pedal (7) is operated, the motor vehicle (1) is allowed to be accelerated by means of the drive device (8) only after a preset waiting time (23) is taken into account when the accelerator pedal (7) is manually operated.

6. The method according to claim 5, wherein, After confirming a second fault (12′) associated with the energy supply unit (11), the drive unit (8) and / or the at least one wheel brake (4) are manipulated to reduce the current propulsion power (24) of the motor vehicle (1).

7. The method according to claim 5, wherein, The at least one wheel brake (4) is an electronic parking brake that is brought to a persistently active state after a second fault (12') associated with the energy supply unit (11) is confirmed, wherein the motor vehicle (1) can continue to be driven by the operation of the accelerator pedal (7) despite the electronic parking brake being in a persistently active state.

8. The method according to claim 1 or 2, wherein, The motor vehicle (1) has a drive system including: an accelerator pedal (7); a drive device (8) for longitudinal control of the motor vehicle (1), the drive device (8) being electronically controllable while taking into account manual operation of the accelerator pedal (7); and an accelerator pedal sensor device (10), wherein the brake pedal sensor device (6) is inoperable due to a confirmed third fault (12′′) associated with the braking system of the motor vehicle (1), wherein - The at least one wheel brake (4) is loaded with a preset basic braking torque (25); -If the accelerator pedal is operated • Accelerator pedal operation information (26) is detected by means of the accelerator pedal sensor device (10), which describes the operation stroke of the accelerator pedal (7) by operation. • If the detected accelerator pedal operation information (26) is less than the accelerator pedal operation limit value (27), then the at least one wheel brake (4) is applied with a special case braking torque (28), which is less than the basic braking torque (25). • If the detected accelerator pedal operation information (26) is greater than or equal to the accelerator pedal operation limit value (27), then acceleration information (30) describing the acceleration of the motor vehicle (1) is determined when the fault condition acceleration determination criterion (29) is applied to the detected accelerator pedal operation information (26), and the drive device (8) is manipulated such that the motor vehicle (1) accelerates according to the acceleration information (30).

9. The method according to claim 8, wherein, If the detected accelerator pedal operation information (26) is less than the accelerator pedal operation limit value (27), the vehicle (1) will not be accelerated, taking into account the detected accelerator pedal operation information (26).

10. The method according to claim 8, wherein, The measured acceleration information (30) is less than the typical acceleration information (30), which is measured when the normal acceleration determination standard (31), which is different from the fault condition acceleration determination standard (29) and is applied when the first fault (12) is not confirmed, is applied to the detected accelerator pedal operation information (26).

11. The method according to claim 8, wherein, After the accelerator pedal (7) is operated, the at least one wheel brake (4) is applied with a preset additional braking torque (33) greater than the basic braking torque (25).

12. The method according to claim 11, wherein, If the accelerator pedal (7) is reoperated and the second accelerator pedal operation information (26′) detected during the reoperation is greater than or equal to the accelerator pedal operation limit value (27), then repeating acceleration information (35) is determined when the repeating acceleration determination criterion (34) is applied to the detected second accelerator pedal operation information (26′), the repeating acceleration information (35) describing the acceleration of the motor vehicle (1) as less than the acceleration determined when the fault condition acceleration determination criterion (29) is applied, and the drive device (8) is operated such that the motor vehicle (1) accelerates according to the repeating acceleration information (35).

13. The method according to claim 8, wherein, A retraction speed value (36) is measured, which describes the speed at which the accelerator pedal (7) is retracted, and if the retraction speed value (36) is greater than the retraction speed limit value (37), the at least one wheel brake (4) is applied with a retraction braking torque (38) greater than the basic braking torque (25).

14. The method according to claim 8, wherein, The motor vehicle (1) has an ambient environment sensor device (39) and uses the ambient environment sensor device (39) to detect sensor data (41) describing at least one ambient environment (40) in the area in front of the motor vehicle (1), wherein an obstacle (43) in the ambient environment (40) in the area in front is determined when an obstacle identification criterion (42) is applied to the detected sensor data (41), and if the obstacle (43) is determined, the at least one wheel brake (4) is applied with an obstacle-related braking torque (44) greater than the basic braking torque (25).

15. A motor vehicle (1) having a braking system, wherein, The motor vehicle (1) is configured to perform the method according to any one of the preceding claims.

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