Method for operating a motor vehicle and motor vehicle

Abstract

A method for operating a motor vehicle (10) equipped with an internal combustion engine (12), a starting device (40) for starting the internal combustion engine (12), and a start-stop control device (30) for controlling the internal combustion engine (12) and the starting device (40), wherein the start-stop control device (30) checks, before initiating a stopping process for the internal combustion engine (12), in particular repeatedly at a predeterminable time interval, whether a stop of the engine is permissible or not, and initiates the stopping process only if it is determined that it is permissible, characterized in that the start-stop control device (30) checks whether there is a start authorization to restart the internal combustion engine (12) and only initiates the stopping process if there is a start authorization,whereby the start authorization is linked to the presence of a key or a data carrier containing start authorization information in the vehicle or in its vicinity.

Description

The invention relates to a method for operating a motor vehicle which is equipped with an internal combustion engine, a starting device for starting the internal combustion engine and a start-stop control device for controlling the internal combustion engine and the starting device, and to a motor vehicle.The use of start-stop control devices in motor vehicles equipped with internal combustion engines is known. A start-stop control device enables automatic shutdown and automatic startup of the internal combustion engine, which are dependent on the driving state of the motor vehicle, in order to ensure economical operation of the motor vehicle. For this purpose, the driver of the motor vehicle does not have to become active beyond the operation of the basic functions (accelerator, brake, clutch, gear shift) of the motor vehicle. An automatic shutdown of the internal combustion engine is carried out in particular when no drive power has to be applied by the internal combustion engine. In a motor vehicle which is equipped with a manual transmission, such a driving state occurs when the motor vehicle falls below a predefined minimum speed for a predefined period of time when the clutch is actuated, that is to say when the transmission of power between the internal combustion engine and the drive wheels is separate. This driving state can occur, for example, when waiting at a traffic light. Automatic starting of the internal combustion engine is triggered in particular by releasing the service brake or the parking brake or by actuating the accelerator pedal, without the driver having to take additional measures or take actions. The start-stop control device influences the energy and / or fuel supply of the internal combustion engine and a starting device which provides the necessary kinetic energy in order to bring the internal combustion engine from standstill to a minimum rotational speed from which autonomous operation and a power output of the internal combustion engine is possible.DE 100 38 280 A1 discloses a method for operating a motor vehicle having the features of the preamble of claim 1. the check as to whether a stop of the engine is permitted is carried out on the basis of the outside air temperature and the engine water temperature. This makes it possible to prevent the operating temperature of a catalytic converter from decreasing too much during an idling stop.EP 1 612 408 A1 discloses a method for automatically stopping and starting an internal combustion engine in a motor vehicle, in which the internal combustion engine is temporarily switched off in certain driving operating states for fuel saving and is restarted by actuating the brake pedal. In this case, a particular emphasis is placed on driving operating states as are encountered in delivery vehicles which are used for the delivery of packages. In this case, the driver often leaves the vehicle, wherein it is assumed here that the internal combustion engine is shut down when leaving the vehicle in order to save fuel and to conserve the environment. The parking of the motor vehicle is carried out by means of a radio key, the presence of which at a predetermined radius around the motor vehicle brings about unlocking of the doors and a readiness for starting of the motor vehicle, while the absence of the radio key leads to locking of the doors and to deactivation of the readiness for starting of the motor vehicle. An automated start of the internal combustion engine should take place when there is a clear start request from the driver, for example by actuating the clutch pedal. Thus, unnecessary starting operations are avoided.From EP 1717116 A2 a method for operating a start-stop control device of a motor vehicle is known, in which the start-stop control device checks, before initiating a starting process for the internal combustion engine, whether there is a starting authorisation for restarting the internal combustion engine and the start-stop control device initiates the starting process either in the case of a present starting authorisation or if an emergency requires this. However, under certain circumstances, the vehicle can therefore also be restarted without the present starting authorization.The object of the invention is to provide a method for operating a motor vehicle and a motor vehicle which enable safe use of the start-stop functions.This object is achieved by a method having the features of claim 1 and by a motor vehicle having the features of claim 5. Advantageous refinements of the invention are the subject matter of dependent claims.According to the invention, it is provided that the start-stop control device checks, before the initiation of a stop process for the internal combustion engine, in particular recurringly in a predeterminable time interval, whether a start authorisation for renewed start of the internal combustion engine is present, and that the start-stop control device initiates the stop process only when the start authorisation is present. The starting authorisation is linked to an object which can be designed as a key for insertion into an ignition lock which optionally contains additional starting authorisation information to be transmitted in a wired or wireless manner, or the object can be designed as a chip card for the wired or / or wireless transmission of starting authorisation information. It is decisive that the start authorization is present when the object provided for detecting the start authorization is received at a location (in particular a key lock) set up for this purpose or is at least located in a predeterminable transmission-reception range of a start authorization interrogation device.If the start authority is present, the driver may start the motor vehicle. The starting process is initiated as soon as the driver gives a corresponding command for this purpose. Such a command can be given in particular by turning a key in an ignition lock, by actuating a start button, by actuating the accelerator pedal, by releasing the brake pedal, by actuating a selector lever for an automatic transmission or by actuating the clutch pedal for engaging a gear in a manual transmission or by a combination of these activities. Before executing the start command, the start-stop control device can check further boundary conditions which ensure reliable startup of the motor vehicle, for example the actuation of the brake pedal in a motor vehicle with an automatic transmission.Once the motor vehicle has been put into operation, the start-stop control device can generate a stop request for the internal combustion engine for predefined situations, by means of which the internal combustion engine is brought to a standstill. The stop request can be generated in particular by changing the driving state, in particular by dropping below a predeterminable minimum speed and actuating the clutch pedal to interrupt the force flow when the gear is engaged or by a relatively long standstill of a motor vehicle equipped with an automatic transmission. In the presence of a stop request, the start-stop control device initiates the stopping process for the internal combustion engine. The internal combustion engine can be brought to a standstill, for example, by switching off the fuel supply and / or by switching off the ignition energy.According to the invention, it is provided that a check is carried out before the initiation of the stop process to determine whether the start authorization continues to be given. The stopping process should only be initiated if the starting authorization continues to exist. However, the start authorisation may have been released since the last start process, for example if the object authorisation for the start has been lost in the meantime. If the driver had stored the smart card that authorized to start in the vehicle and had been moved out of the vehicle by the relative wind, for example, the situation is present that when the internal combustion engine was automatically shut off, a restart would no longer be possible, since the starting authorization of the driver is checked before the start process was carried out. In the above case, the starting authorisation is no longer present at this time, since the corresponding chip card has been lost. The driver could thus no longer start the vehicle, which leads to considerable adverse effects. In the method according to the invention, on the other hand, it is checked before the internal combustion engine is switched off whether the start authorization is still present and, despite the lack of start authorization, it is assumed that the authorized driver continues to drive the vehicle, so that switching off the internal combustion engine, combined with the inability to restart, would be unwarranted. In such a situation, according to the invention, automatic shutdown of the internal combustion engine is prevented by the start-stop control device, and the start-stop strategy followed by the start-stop control device is disabled.Furthermore, it can additionally or alternatively be provided that the start authorization is checked before an automatic starting process for the internal combustion engine, i.e. initiated by the start-stop control device, which usually follows a stop process initiated by the start-stop control device. Only when the start authorization is present is a starting process carried out, which is initiated, for example, by engaging a gear or by actuating the clutch pedal as part of the start-stop strategy. This prevents the motor vehicle from being put into operation after an automatic shutdown by an unauthorized person or by the authorized person erroneously. If the authorized driver leaves the motor vehicle after an automatic shutdown of the internal combustion engine, he usually also takes the object or objects authorized to start with him. If the driver later returns to the vehicle without the object authorized to start, the method according to the invention prevents the driver from being able to set the internal combustion engine in motion solely by operating the motor vehicle according to the predefined start-stop strategy.Otherwise, the situation could arise in which, after loss of the object authorized to start and after complete shutdown of the internal combustion engine, for example by actuating a switch-off button, the driver establishes at another location and upon a new request for startup that the object authorized to start no longer carries the object authorized to start and then possibly remains lying at a location which is far from the location at which the object authorized to start is located.In one embodiment of the invention, it is provided that the start-stop control device deactivates a start-stop strategy until the start authorization is present again. As a result, the motor vehicle can continue to travel as soon as the object authorized to start is again in the reception range of the start-stop control device.In a further embodiment of the invention, it is provided that the start-stop control device deactivates a start-stop strategy until the start authorization is present again and a start request of the driver independent of the start-stop strategy is additionally present. This ensures that after leaving the motor vehicle, in which the object authorized to start has been removed from the reception range of the start-stop control device and entering the motor vehicle again, the driver is not surprised by an automatically occurring starting process, which is caused, for example, by engaging a gear or actuating the clutch pedal. Instead, it is provided that the driver, in addition to the direct operation of the motor vehicle, must take an action such as the actuation of a start button before the starting process for the internal combustion engine is initiated.In a further embodiment of the invention, it is provided that the start-stop control device emits a warning signal in the absence of the start authorisation. This ensures that the driver is informed directly about the reason for which the motor vehicle cannot be started in the absence of the starting authorisation. The warning signal can be emitted optically and / or acoustically, for example by a warning light and / or a warning sound. The warning signal can also be output when the loss of the object authorized for starting occurs when the internal combustion engine is running.According to a further aspect of the invention, a motor vehicle having an internal combustion engine and a starting device for starting the internal combustion engine is provided, which motor vehicle has a start-stop control device for controlling the internal combustion engine and the starting device, which is set up to carry out the method according to one of Claims 1 to 4.In a further embodiment of the invention, it is provided that the starting device is designed as an integrated starter generator (ISG), in particular as a belt-coupled integrated starter generator (B-ISG). An integrated starter generator takes over both the function of the generator for generating electrical energy and of the starter for providing kinetic energy for the starting process of the internal combustion engine. The integrated starter generator is preferably coupled to the crankshaft of the internal combustion engine via a drive belt, e.g. a toothed belt, or is flange-connected directly to the crankshaft. The integrated starter generator is preferably in constant force-transmitting connection with the internal combustion engine and can thus provide kinetic energy to the internal combustion engine at any desired point in time (in particular in contrast to a standard starter motor with pinion engagement in a flywheel). It is also conceivable to design the force-transmitting connection between integrated starter generator and internal combustion engine to be separable by means of a switchable or speed-dependent clutch device, wherein here too direct provision of kinetic energy can be ensured.Further advantages and features of the invention are evident from the claims and from the following description of advantageous embodiments, which are illustrated on the basis of the drawings. The following shows: FIG. 1 shows a schematic illustration of a motor vehicle with an internal combustion engine, an integrated belt-driven starter generator and a start-stop control device, FIG. 2 shows a flow chart for illustrating the start-stop method.FIG. 1 schematically shows a motor vehicle 10 having the essential components which play a role in carrying out a start-stop method with the possibility of stopping the stop process. Further components necessary for operating the motor vehicle 10 are not shown for the sake of clarity.The motor vehicle 10 has an internal combustion engine 12 which is connected via a clutch device 14 to a manual transmission 16 on which drive wheels 18 are flanged. When clutch 14 is closed, a torque delivered by internal combustion engine 12 is converted by means of transmission 16 into an output torque for drive wheels 18 and thus enables the motor vehicle 10 to move forward.The travel speed of the motor vehicle 10 is influenced by adjusting the power provided by the internal combustion engine 12 and selecting the suitable transmission setting or gear selection (forward gears, reverse gear). These settings are made by means of known operating elements such as accelerator pedal 20 and gear selector lever 22, which are operated by the driver. A clutch pedal 24 serves to actuate the clutch 14 via an actuating device, not shown, and thus to disconnect and restore the force flow between the internal combustion engine 12 and the transmission 16. The speed of the motor vehicle 10 can also be influenced by means of a brake pedal 26 which acts via brake lines on a brake system, not shown in detail, assigned to the drive wheels 18.The actuation positions of the operating elements 20, 22, 24, 26 are detected with the aid of sensors, not shown in detail, the signals of which are transmitted via signal lines 28 to a start-stop control device 30. By time-derived actuation positions, the actuation speeds for the operating elements 20, 22, 24 and 26 can also be determined. The start-stop control device 30 is connected via additional control lines 28 to components such as a battery monitoring system 32, an ignition control unit 34, a fuel injection device 36 and a sensor arrangement 38 assigned to the internal combustion engine 12. The control device 30 can also process values determined by these components and output control commands to these components.The schematically illustrated sensor arrangement 38 on the internal combustion engine comprises sensors such as a rotational speed sensor, an air mass flow meter, a cooling water temperature sensor, an oil temperature sensor and / or other sensors for determining operating characteristic values of the internal combustion engine 12.The internal combustion engine 12 is assigned an integrated starter generator 40, which is permanently coupled via a belt 42 to the crankshaft, not shown in detail, of the internal combustion engine 12 (B-ISG). The starter generator 40 is electrically connected to the start-stop controller and to a battery 44 used as an electric power storage. The starter generator 40 serves in its function as a starter for providing kinetic energy in order to accelerate the internal combustion engine 12 from standstill to a minimum rotational speed, starting from which an independent operation of the internal combustion engine 12 is possible. Operating as a generator, the starter generator 40 converts kinetic energy of the internal combustion engine 12 into electrical energy that is stored in the battery 44. The control or regulation of the kinetic energy or the electrical energy to be provided by the starter generator 40 is carried out by the start-stop control device 30. The starter generator 40 is dimensioned such that it can provide an assistance torque even when the internal combustion engine 12 is running, in order to improve acceleration of the motor vehicle or even to enable a purely electric movement of the motor vehicle 10, in particular at low speeds.The start-stop control device 30 is configured such that automatic shutdown and cranking of the internal combustion engine 12 can be carried out. A deactivation of the internal combustion engine 12 is provided if the internal combustion engine 12 does not have to deliver any power to the drive wheels or to consumers such as a belt-coupled air conditioning compressor 46 over a predeterminable period of time.In order to ensure an economical and environmentally friendly operation of the motor vehicle 10, a stop request is generated in the start-stop control device when one or more of the conditions listed below are present and is used to actuate the internal combustion engine 12, the ignition control device 34, the fuel injection device 36 and the starter generator 40, in particular in order to interrupt the fuel supply and / or the ignition energy supply to the internal combustion engine 12.The start-stop control device 30 checks, in particular, whether, after a minimum speed of the motor vehicle 10 has been undershot, the actuating position and / or actuating speed of the accelerator pedal 20 and / or of the clutch pedal 24 and / or of the brake pedal 26 and / or of the gear selector lever 22 is within a predeterminable value range in such a way that a stop request is expedient.The method illustrated in FIG. 2 on the basis of the flow chart is started by a start command initiated by the driver. This start command can be given, for example, by actuating a starter button, not shown. After the start-stop control device 30 has detected the actuation of the starter button, a check is made as to whether there is an authorisation to start the motor vehicle 10. This can be linked in particular to the presence of a wirelessly readable chip card in the transmission-reception range of a driving authorisation system assigned to the start-stop control device 30, which is not shown in more detail. If the correct chip card is located in the transmission-reception range of the driving authorisation system, this issues an enable signal to the start-stop control device 30, which then initiates the starting process for the internal combustion engine 12. If there is no authorisation to start the internal combustion engine 12, the internal combustion engine 12 is not started and a warning signal can be output.When the authorization for the starting process is present, the internal combustion engine 12 is started and the motor vehicle 10 can be driven. During the driving operation, the start-stop control device 30 can automatically shut down the internal combustion engine 12 without the need for a driver's intervention directed towards it. For example, the automated shutdown can take place with prolonged actuation of the brake pedal 26 and of the clutch pedal 24. For this purpose, a stop request for the internal combustion engine 12 is generated by the start-stop control device 30. Before executing the stop request, the start-stop control device 30 checks whether the presence of the chip card established at the beginning of the startup of the motor vehicle 10 still remains in the reception range of the driving authorisation system. If this is the case, the internal combustion engine 12 is automatically stopped, in particular by shutting down the ignition control unit 34 and / or the fuel injection device 36.If, on the other hand, the internal combustion engine 12 could be stopped in an automated manner, the driver can now leave the motor vehicle 10 without carrying out a final shutdown of the start-stop control device 30, for example in order to make a short notice. If the driver then returns again and actuates one or more operating devices of the motor vehicle 10, such as the accelerator pedal 20 or the clutch 24, the start-stop control device 30 generates a start request from this. If a start request is present and the driver continues to carry the chip card as proof of the authorization to start the internal combustion engine 12, the internal combustion engine 12 can be started. If, on the other hand, the driver no longer carries the chip card with him, the provided checking of the start authorization fails negatively and no starting of the internal combustion engine 12 can take place. Rather, a corresponding warning message is output, which indicates to the driver that he is not authorized to start.In another embodiment, it can be provided that, in addition, a request for a starter button is provided for checking the presence of the driving authorisation after the automated execution of a stop process. Thus, even if the starting authorization is positively checked after the determination of the starting request, an action of the driver directed to the starting of the internal combustion engine 12 is required. This prevents a surprising starting of the internal combustion engine.In another embodiment of the invention, the presence of the starting authorization is checked in regular or irregular cycles and a warning message is output if the starting authorization is lost, independently of an imminent automated stopping process or starting process.

Claims

Method for operating a motor vehicle (10) which is equipped with an internal combustion engine (12), a starting device (40) for starting the internal combustion engine (12) and a start-stop control device (30) for actuating the internal combustion engine (12) and the starting device (40), wherein the start-stop control device (30) checks, before initiation of a stop process for the internal combustion engine (12), in particular recurringly in a predeterminable time interval, whether or not a stop of the engine is permitted, and initiates the stop process only if permission is established, characterized in that the start-stop control device (30) checks whether or not there is a start permission for renewed starting of the internal combustion engine (12), and initiates the stop process only if the start permission is present, wherein the starting authorisation is linked to the presence of a key or a data carrier containing starting authorisation information in the vehicle or in the vicinity thereof.Method according to Claim 1, characterized in that the start-stop control device (30) deactivates a start-stop strategy until the start authorisation is again present.Method according to Claim 1, characterized in that the start-stop control device (30) deactivates a start-stop strategy until the start authorisation is again present and, in addition, a start request of the driver which is independent of the start-stop strategy is present.Method according to one of the preceding claims, characterized in that the start-stop control device (30) emits a warning signal in the absence of the start authorisation.Motor vehicle (10) having an internal combustion engine (12) and a starting device (40) for starting the internal combustion engine (12), characterized bya start-stop control device (30) for actuating the internal combustion engine (12) and the starting device (40) which is set up to carry out the method according to one of Claims 1 to 4.Motor vehicle according to Claim 5, characterized in that the starting device (40) is designed as an integrated starter generator, in particular as a belt-coupled integrated starter generator.

Images