Method for operating a motor vehicle

Abstract

Method for operating a motor vehicle (1), - wherein the motor vehicle (1) has a parking brake device (2) which, in a locking position, prevents the motor vehicle (1) from rolling, - wherein the motor vehicle (1) has an on-board network (4) with an electrical energy supply device (6) which electrically supplies the parking brake device (2), - wherein the motor vehicle (1) has a triggering device (11) which is adjustable between an active position for activating the motor vehicle (1) and a deactive position for deactivating the motor vehicle (1), - wherein the triggering device (11) is designed in the manner of an ignition (12), characterized in - that when the release device (11) is adjusted to the deactivated position, the parking brake device (2) is electrically supplied with energy by the energy supply device (6) and adjusted to the locking position, - that the motor vehicle (1) is deactivated when the parking brake device (2) is set to the locking position.

Description

The present invention relates to a method for operating a motor vehicle, which has a parking brake device, an on-board power supply system and a triggering device for activating and deactivating the motor vehicle. The invention further relates to a motor vehicle operated in this way.A parking brake device of a motor vehicle usually comprises at least one parking brake, also known to the person skilled in the art as a parking brake, which prevents rolling of the motor vehicle by adjusting in a corresponding position, which is also referred to below as a locking position.The parking brake device is used in particular to prevent the motor vehicle from rolling in a parking position. In addition, the parking brake device is usually adjusted into the locking position when the motor vehicle is shut down.It is known to automatically perform the adjustment of the parking brake device, for example when the motor vehicle is parked and deactivated, in particular deactivated. The deactivation and activation of a motor vehicle is usually carried out by means of a triggering device, for example an ignition, which is adjusted accordingly in order to activate and deactivate the motor vehicle. It is known here to automatically adjust the parking brake device into the locking position when adjusting the triggering device into a deactivated position for deactivating the motor vehicle when deactivating the motor vehicle.DE 10 2017 211 398 A1 discloses a motor vehicle having a parking assistance system. In this case, an on-board power supply system of the motor vehicle is monitored for critical voltage characteristics by means of a monitoring unit. If such a critical course occurs, a brake system of the motor vehicle is activated to achieve a safe state.In DE 10 2015 203 490 A1, a parking brake is actuated during stop phases of automatic start-stop system of a motor vehicle in order that a vehicle driver can remove his foot from the brake pedal in the stop phase.Further motor vehicles with parking brakes are known from DE 10 2017 201 066 A1, DE 10 2016 203 020 A1 and DE 10 2019 200 608 A1.Parking brake devices of motor vehicles are usually electrically supplied. The electrical supply is effected via an on-board power supply system of the motor vehicle, which additionally electrically supplies other electrical loads of the motor vehicle. The on-board power supply system comprises a device for supplying electrical energy, also referred to below as an energy supply device. When the motor vehicle is deactivated, a generator of electrical energy, for example a generator, is usually likewise deactivated. When the motor vehicle is deactivated, the generator, in particular the generator, is deactivated on the one hand and the parking brake device is simultaneously adjusted into the locking position. There is thus the risk that the electrical energy present in the motor vehicle is not sufficient for adjusting the parking brake device, so that an adjustment of the parking brake device into the locking position does not occur.From the document DE 20 217 103 598 U1 a vehicle with an automatic transmission is known, in which a parking mechanism is integrated.The document DE 10 2007 027 358 A1 discloses a method for maintaining the braking force of a vehicle when it is determined that a distance between the vehicle and an obstacle is undershot.From the document DE 199 08 062 A1 a service brake device with an electromechanically actuatable locking function for realizing a locking function of the wheel brakes is known.The present invention is concerned with the object of specifying improved or at least other embodiments for a method for operating a motor vehicle of the type mentioned at the outset and for a motor vehicle of this type, which embodiments are distinguished in particular by increased safety and / or availability.This object is achieved according to the invention by the subject matter of the independent claims. Advantageous embodiments are the subject of the dependent claims.The present invention is based on the general idea of delaying the deactivation of the motor vehicle, but at least of an energy supply device of the motor vehicle, when triggering or the desire to deactivate a motor vehicle, until a parking brake device of the motor vehicle is adjusted into a locking position in which rolling of the motor vehicle is prevented. This prevents the parking brake device from being unable to be adjusted into the locking position or at least reducing the risk involved due to a lack of electrical energy in the motor vehicle. In particular, it is possible in this way to implement the adjustment of the parking brake device into the locking position nevertheless in the event of damage or a defect in a rechargeable battery of the motor vehicle. As a result, the safety of the motor vehicle is increased and improved redundancy for adjusting the parking brake device and increased availability are achieved.According to the concept of the invention, the motor vehicle has the parking brake device which prevents rolling of the motor vehicle in a locked position. The motor vehicle further comprises an on-board power supply system which has an electrical energy supply device. The on-board power supply system and thus the energy supply device electrically supply the parking brake device. The parking brake device thus draws electrical energy from the on-board electrical system for adjusting the parking brake device. The motor vehicle further has a triggering device for activating and deactivating the motor vehicle. For this purpose, the triggering device is adjustable between corresponding positions. The triggering device is therefore adjustable between an active position for activating the motor vehicle and a deactivated position for deactivating the motor vehicle. According to the invention, when the triggering device is adjusted into the deactivated position, the parking brake device is electrically supplied with the energy supply device and adjusted into the locked position and the motor vehicle is subsequently deactivated.The energy supply device serves for the electrical supply of electrical loads of the motor vehicle, which also include the parking brake device. For this purpose, the consumers are electrically connected to the on-board power supply system.It is conceivable to configure the on-board power supply system in such a way that the electrical connection for supplying the respective electrical load can be established and disconnected. This is effected, for example, via corresponding switches, which are also referred to below as load switches. The respective load switch can disconnect the electrical connection to at least one associated load if at least one of the at least one associated loads is defective.The energy supply device advantageously comprises a generator for generating an electrical voltage. It is conceivable that the generator for generating the electric voltage is connected or connectable to a drive device of the motor vehicle.Alternatively or additionally, the energy supply device comprises at least one rechargeable battery.Embodiments are preferred in which it is checked before the adjusting of the parking brake device whether the motor vehicle is stationary. In this case, a speed of the motor vehicle is checked before the parking brake device is adjusted into the locking position and the parking brake device is adjusted into the locking position only if the speed of the motor vehicle is below a predefined threshold. This prevents, in particular, the parking brake device from being moved into the locking position while the motor vehicle is moving and thus causes an unintentionally abrupt braking of the motor vehicle.The deactivation of the motor vehicle advantageously corresponds to a deactivation of the motor vehicle. The activation of the motor vehicle advantageously corresponds to the motor vehicle being switched on.Advantageously, a drive device of the motor vehicle is deactivated when the motor vehicle is deactivated.Preferably, the motor vehicle is moved into a standby mode, also known as standby mode, when deactivated. In standby operation, at least one load of the motor vehicle can be electrically supplied via the on-board power supply system. In this case, the load expediently draws the electrical energy from at least one of the at least one battery of the motor vehicle.The triggering device is designed in the manner of an ignition, which is adjustable between an "on" and an "off" position in order to activate and deactivate the motor vehicle. In this case, the on position corresponds to the active position and the off position corresponds to the inactive position.The on-board power supply system is preferably designed in such a way that the electrical connection of the generator or of the at least one battery is disconnected from the on-board power supply system if a corresponding defect of the generator or of the battery is detected. This means that the electrical connection of the generator to the on-board power supply system is disconnected if the generator is defective and / or that the electrical connection of the defective battery to the on-board power supply system is disconnected if the battery is defective. In this way, undesired influences of the defective generator or the defective battery on the on-board power supply system are prevented or at least reduced and the availability of the on-board power supply system is thus increased.In order to disconnect the generator or the battery from the on-board power supply system in the event of a defect, the on-board power supply system can have a safety device which is also known to the person skilled in the art as a "Powernet Guardian" or "PNG" for short. The safety device advantageously comprises control electronics or power electronics which are arranged between the generator and the battery and are designed in such a way that they can electrically separate the defective battery or the defective generator from the on-board power supply system at least temporarily. For this purpose, the safety device can have at least one switch.It is understood that, in addition to the method, a motor vehicle of the type described above and explained further below also belongs to the scope of this invention.The motor vehicle expediently comprises a control device which is designed in such a way that it operates the motor vehicle accordingly. For this purpose, the control device can contain a computer program product, for example.The control device is expediently connected to the parking brake device and the triggering device in a communicating manner.Further important features and advantages of the invention are evident from the dependent claims, from the drawings and from the associated description of the figures with reference to the drawings.It is understood that the features mentioned above and those still to be explained below can be used not only in the respectively specified combination, but also in other combinations or alone, without departing from the scope of the present invention.Preferred exemplary embodiments of the invention are illustrated in the drawings and are explained in more detail in the following description, wherein the same reference numerals refer to the same or similar or functionally the same components.They show, in each case schematically FIG. 1 shows a greatly simplified schematic diagram of a motor vehicle having an on-board power supply system and a parking brake device, FIG. 2 shows a circuit diagram-like illustration of the on-board power supply system, FIG. 3 shows a flow chart for explaining the method for operating the motor vehicle, FIG. 4 shows a circuit diagram-like illustration of the on-board power supply system in another exemplary embodiment, FIG. 5 shows a circuit diagram-like illustration of the on-board power supply system in a further exemplary embodiment.A motor vehicle 1, as is represented in FIG. 1 in a greatly simplified manner and in the manner of a circuit diagram, is operated according to the method described by way of example in FIG. 3 on the basis of a flow chart.The motor vehicle 1 comprises a parking brake device 2 with which rolling away of the motor vehicle can be prevented. For this purpose, the parking brake device 2 is adjusted into a position which is also referred to below as the locking position. The parking brake device 2 interacts with at least one wheel 3 of the motor vehicle 1. In the locked position, at least one parking brake 10 of the parking brake device 2 blocks an associated wheel 3.The parking brake device 2 is adjusted electrically by means of an on-board power supply system 4, which is shown in FIGS. 1 and 2 and 4 and 5. The on-board power supply 4 accordingly serves for the electrical supply of the parking brake device 2 as an electrical load 5. In the exemplary embodiments shown, the on-board power supply 4 additionally serves for the electrical supply of further electrical loads 5. The energy supply device 6 can comprise a generator 7 and / or a rechargeable battery 8. In the exemplary embodiments shown, the respective energy supply device 6 comprises both a generator 7 and at least one battery 8.The motor vehicle 1 further has a drive device 9 for driving the motor vehicle 1. The drive device 9 is preferably, as can be seen from FIG. 1, drive-connected or drive-connectable to the generator 7, so that the generator 7 can generate electrical energy during operation of the drive device 9, in particular provide an electrical voltage in the on-board power supply 4.The motor vehicle 1 is adjustable between an active state and a deactivated state. The inactive state preferably corresponds to a standby mode. The adjustment of the motor vehicle 1 between the active state and the inactive state is initiated or triggered by means of a triggering device 11 which is designed in the manner of an ignition 12. In this case, the triggering device 11 is adjusted to a deactivated position for adjusting the motor vehicle 1 into the deactivated state and to an active position for adjusting the motor vehicle 1 into the active state.The motor vehicle 1 further comprises a control device 13 which is designed for operating the motor vehicle 1 according to the method described below. The control device 13 is connected here in a communicating manner to the triggering device 11, the on-board power supply system 4 and the drive device 9.According to FIG. 3, during operation of the motor vehicle 1, a check is made in a method measure 14 as to whether the triggering device 11 is moved into the deactivated position. In this method measure 14, it is thus checked whether the desire to deactivate the motor vehicle 1 is present. This method measure 14 is therefore also referred to below as deactivation request measure 14. If the adjustment of the triggering device 11 into the deactivated position is detected in the deactivation request measure 14, then the parking brake device 2 is subsequently electrically supplied by means of the on-board electrical system 4 and adjusted into the locked position in a method measure 15. This measure 15 is also referred to below as a fixing measure 15. If the parking brake device 2 is adjusted into the locking position, the deactivation of the motor vehicle 1 takes place in a method measure 16, wherein this method measure 16 is also referred to below as deactivation measure 16. After deactivation measure 16, the method is ended, as indicated in FIG. 3 with reference numeral 17.In order to carry out deactivation of the motor vehicle 1 only after the complete adjustment of the parking brake device 2 into the locking position, a further method measure 18 can be carried out between the locking measure 15 and the deactivation measure 16, as can be seen from FIG. 3, in which method measure it is checked whether the parking brake device 2 has been adjusted into the locking position. This is effected in particular with the aid of feedback from the parking brake device 2, which is output by the parking brake device 2 when the parking brake device 2 is adjusted into the locking position. This method measure 18 is also referred to below as feedback measure 18. This means that after the fixing measure 15, the feedback measure 18 takes place and the deactivation measure 16 is carried out after feedback has been provided for the effected adjustment of the parking brake device 2 into the fixing position. Alternatively or additionally, it is possible to wait for a predefined period of time after the detection measure 15 and then to carry out the deactivation measure 16.As can also be seen from FIG. 3, it is provided in the exemplary embodiment shown that the parking brake device 2 is adjusted into the locking position only when the motor vehicle 1 is stationary. In the exemplary embodiment shown, prior to deactivation request measure 14, a measure 19 is carried out, which is also referred to below as standstill measure 19. In this case, the method only continues to the deactivation request measure 14 if a standstill of the motor vehicle 1 is detected in the standstill measure 19. This can be done by checking the speed of the motor vehicle 1, wherein a standstill of the motor vehicle 1 is assumed below a predefined speed threshold. If this is not the case, the method returns to the standstill measure 19 in the manner of a loop until said speed threshold is undershot.As can also be seen from FIG. 3, the described method can be switched on and off in the exemplary embodiment shown. The method is therefore only used when a corresponding activation of the method is present. In this case, before the method is carried out, in the present case therefore before the standstill measure 19 is carried out, a check is initially carried out in a check measure 20 as to whether the method is to be carried out. It is conceivable in particular for a vehicle driver to specify the execution of the method by adjusting a corresponding operating element.In the exemplary embodiment of the on-board power supply system 4 shown in FIG. 2, the on-board power supply system 4 is kept as simple as possible and has the generator 7 and the battery 8. In this case, the on-board power supply system 4 is electrically connected to the parking brake device 2 and to the further electrical loads 5.In the exemplary embodiment shown in FIG. 4, the on-board power supply system 4 has the generator 7 and two batteries 8. In this case, a safety device 21 is provided between the energy supply device 6 and the on-board power supply system 4, which safety device has various switches 22 and control and power electronics. With the switches 22, an electrical connection of the generator 7 and at least one of the batteries 8 can be temporarily electrically disconnected from the on-board power supply system 4. This occurs in particular when there is a defect in the generator 7 or the at least one battery 8. Here, the switches 22 are shown purely by way of example in an open position, in which they disconnect the respective electrical connection. In the exemplary embodiment shown in FIG. 4, the on-board power supply system 4 comprises a high-voltage power supply system circuit 23 and a low-voltage power supply system circuit 24, which are operated at different voltages. The high-voltage power supply circuit 23 is operated, for example, at 48 volts and the low-voltage power supply circuit 24 at 12 volts. In the exemplary embodiment shown, the generator 7 is integrated together with one of the batteries 8 in the high-voltage power supply circuit 23. In contrast, parking brakes 10 and the safety device 21 are incorporated in the low-voltage network circuit 24. The safety device 21 is in this case able by means of the switches 22 to separate the two mains circuits 23, 24 from one another or to connect them to one another. The on-board power supply system 4 of the exemplary embodiment shown furthermore has a converter 25, in particular a DC / DC converter 26, between the two power supply circuits 23, 24. As can also be seen from FIG. 4, the on-board power supply system 4 has further switches 27 in order to establish and disconnect the electrical connection to the respective load 5. These switches 27 are also referred to below as load switches 27. The electrical connection to the respectively associated load 5 is disconnected in particular when the associated electrical load 5 is defective. The load switches 27 are also shown here, purely by way of example, in an open position.A further exemplary embodiment of the on-board power supply system 4 is shown in FIG. 5. This exemplary embodiment differs from the exemplary embodiment shown in FIG. 4 in that no generator 7 but a battery 8 is incorporated in the high-power network circuit 24.

Claims

Method for operating a motor vehicle (1), - wherein the motor vehicle (1) has a parking brake device (2) which, in a locking position, prevents the motor vehicle (1) from rolling, - wherein the motor vehicle (1) has an on-board power supply system (4) with an electrical energy supply device (6) which electrically supplies the parking brake device (2), - wherein the motor vehicle (1) has a triggering device (11) which is adjustable between an active position for activating the motor vehicle (1) and a deactivated position for deactivating the motor vehicle (1), - wherein the triggering device (11) is designed in the manner of an ignition (12), characterized - in that, when the triggering device (11) is adjusted into the deactivated position, the parking brake device (2) is electrically supplied with the energy supply device (6) and is adjusted into the locking position, - in that the motor vehicle (1) is deactivated, when the parking brake device (2) is adjusted into the locking position.Method according to Claim 1, characterized in that a speed of the motor vehicle (1) is checked before the parking brake device (2) is moved into the locking position, and the parking brake device (2) is moved into the locking position if the speed of the motor vehicle (1) is below a predefined threshold.Method according to Claim 1 or 2, characterized in that, when it is deactivated, a drive device (9) of the motor vehicle (1) is deactivated.Method according to one of Claims 1 to 3, characterized in that, when the motor vehicle (6) is deactivated, it is moved into a standby mode.Method according to one of Claims 1 to 4, characterized in that the on-board power supply system (4) has a generator (7) and a rechargeable battery (8), wherein the electrical connection of the generator (7) to the on-board power supply system (4) is disconnected if the generator (7) is defective, and / or wherein the electrical connection of the battery (8) to the on-board power supply system (4) is disconnected if the battery (8) is defective.Motor vehicle (1), - with a parking brake device (2) which, in a locked position, prevents the motor vehicle (1) from rolling, - with an on-board power supply system (4) which has an electrical energy supply device (6) and which can be electrically connected to the parking brake device (2) for adjusting the parking brake device (2), - with a triggering device (11) which is designed in the manner of an ignition (12) and can be adjusted between an active position for activating the motor vehicle (1) and a deactivated position for deactivating the motor vehicle (1), - with a control device (13) which is designed in such a way that it operates the motor vehicle (1) according to the method according to one of Claims 1 to 5.Motor vehicle according to Claim 6, characterized in that the energy supply device (6) has a generator (7) for generating an electrical voltage.Motor vehicle according to Claim 6 or 7, characterized in that the energy supply device (6) has a rechargeable battery (8).Motor vehicle according to Claims 7 and 8, characterized in that the on-board power supply system (4) has a safety device (21) which is designed in such a way that it disconnects the electrical connection of the generator (7) to the on-board power supply system (4) if the generator (7) is defective, and / or in that it disconnects the electrical connection of the battery (8) to the on-board power supply system (4) if the battery (8) is defective.

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