Method for activating a sailing mode in a motor vehicle

Abstract

Method for activating a sailing mode in a motor vehicle, in which the kinetic energy of the motor vehicle is used to roll as far as possible without the drag torque of the engine braking the motor vehicle, wherein when an automatic cruise control is switched off, the engine can be switched to the sailing mode, characterized in that the cruise control (ACC) can be deactivated completely or at least temporarily in at least two ways (button, BP) and, depending on the type of deactivation (button, BP) of the cruise control (ACC), is switched to the sailing mode (SeM) or to a coasting mode (SB), in which the motor vehicle is braked by the drag torque of the engine.

Description

[0001] The invention relates to a method for activating a so-called sailing mode in a motor vehicle, in which the kinetic energy of the motor vehicle is used to roll as far as possible without the drag torque of the engine braking the motor vehicle, according to the preamble of claim 1.

[0002] It is a well-known fact that motor vehicles consume very little fuel when coasting, that is, when they use their kinetic energy to coast as far as possible without being slowed down by the engine's drag torque. This condition can be achieved in an automatic vehicle, for example, by shifting the selector lever to "N"; in a manual vehicle, by depressing the clutch or engaging neutral.

[0003] Sailing is used relatively rarely in automatic transmissions and practically never in manual transmissions. This is due to the cumbersome operation required to access sailing mode.

[0004] DE 10 2010 062 756 A1 already discloses a motor vehicle that automatically switches to coasting mode under certain circumstances. If a braking request is detected prematurely (i.e., before the brake pedal is applied), a command to activate coasting or overrun mode is issued depending on the driver's braking request.

[0005] Particularly in vehicles with high drag torque when the accelerator pedal is released and a cruise control function, the (sudden) build-up of the full drag torque when the speed control is ended results in a vehicle deceleration that is uncomfortable for the driver and is usually not even desired.

[0006] DE 10 2008 029 453 A1 already discloses a method for setting a coasting mode while taking cruise control into account. When the cruise control is deactivated, the vehicle switches to coasting mode, and when the target speed set on the cruise control is reduced, the vehicle switches to coasting mode or brakes. Here, a distinction is made only between deactivating the cruise control and reducing the target speed.

[0007] The further technical background includes DE 10 2007 031 541 A1, which discloses a speed controller for a motor vehicle.

[0008] It is an object of the present invention to provide an improved method for activating the sailing mode taking into account automatic speed control.

[0009] This object is achieved by a method according to patent claim 1. Advantageous further developments emerge from the dependent claims.

[0010] The invention is based on a method for activating a sailing mode in a motor vehicle, in which the kinetic energy of the motor vehicle is used in sailing mode in order to roll as far as possible without the drag torque of the engine braking the motor vehicle, and wherein the engine can be switched to sailing mode when an automatic cruise control is switched off.

[0011] The basic idea of ​​the invention is to further differentiate the possible activation of the coasting mode depending on the operating action or system status of the cruise control. Accordingly, the invention provides that, assuming that the (active) cruise control can be deactivated in at least two different ways, depending on the type of deactivation of the cruise control, the system switches to coasting mode or to overrun mode, in which the motor vehicle is braked by the drag torque of the engine. The term "deactivation" is generally understood to mean both a complete deactivation of the cruise control (switching off) and a temporary deactivation (interruption) of the cruise control. Likewise, the cruise control can be any type of automatic cruise control, i.e.It is also irrelevant whether (at the current time) a speed control is taking place to a predetermined target speed or to a predetermined distance to a target object ahead.

[0012] According to a preferred development, the engine is disconnected from the drivetrain in coasting mode. This can advantageously be achieved by automatically actuating the clutch or automatically engaging neutral gear. According to an advantageous embodiment, the motor vehicle's engine can also be completely switched off in coasting mode. In a vehicle without a manual transmission, for example an electric vehicle, a zero torque is set on the drive motor in coasting mode or a drag torque is applied, which is required (only) to control the generator, in particular in such a way that the operation of the drive motor is ensured, and / or to cover the on-board electrical system requirements.In other words, in sailing mode, a torque is set on the drive train whose generator power generated thereby supports or ensures the power requirement of the drive engine to maintain the operation of the drive engine and / or the requirement of the on-board network through the generator power of the drive engine to maintain the functionality of the on-board network.

[0013] In the following, various configurations are shown as to when and based on which action the system switches to sailing mode or to overrun mode.

[0014] If, for example, the cruise control can be deactivated (completely or temporarily) by pressing a button located on the steering wheel or a steering column stalk, or by pressing the accelerator or brake pedal, then in an advantageous embodiment of the invention, when the cruise control is deactivated (completely or temporarily), the vehicle can be switched to coasting mode by pressing the button. When the cruise control is deactivated (completely or temporarily), the vehicle can be switched to coasting mode by pressing the accelerator or brake pedal. It is irrelevant whether the automatic cruise control is deactivated completely or only temporarily.

[0015] Alternatively or additionally, a distinction can also be made between complete deactivation (i.e., switching off) and temporary deactivation (i.e., interrupting) of the cruise control. Advantageously, the method according to the invention can be configured such that, upon complete deactivation of the cruise control (e.g., by pressing a corresponding button), the system switches to coasting mode, and upon temporary deactivation (e.g., by pressing the brake pedal), the system switches to coasting mode. The only important thing is that the two types of deactivation occur in different ways.

[0016] If the cruise control is deactivated, the vehicle can be exited again by pressing the accelerator or brake pedal, for example. This allows the driver to exit coasting mode at any time with a simple and intuitive operation.

[0017] As already mentioned above, with all solution variants, the engine can also be switched off completely in coasting mode, thus saving additional fuel, similar to the automatic start / stop systems already available today. However, this requires that the appropriate technical requirements make it unnecessary for the engine to run continuously.

[0018] For the sake of completeness, it should be noted that the method according to the invention is particularly suitable for vehicles in which a high drag torque may be generated when deactivating cruise control (such as in electrically powered vehicles), thus preventing an uncomfortable drag torque when deactivating the automatic cruise control. At the same time, the driver is given the option of switching to coasting mode without strenuous pedal interaction, which also allows the driver to experience the positive aspects of coasting mode.

[0019] The invention will now be explained in more detail using the following exemplary embodiment. The single figure shows a highly simplified flowchart illustrating a method for activating a coasting mode when exiting automatic cruise control.

[0020] The function underlying the method presented here is implemented in software in a control unit, e.g., the engine control unit of a motor vehicle equipped with an electric drive. The motor vehicle has a so-called ACC system, in which the speed is regulated either to a predefined target speed or a predefined distance depending on the detection of a target object ahead. The ACC system is designed in such a way that the cruise control can be deactivated in various ways. Firstly, an appropriately designed button is provided; when pressed, the cruise control is either interrupted (if it was previously active), i.e., temporarily deactivated, or switched off (if it was previously interrupted), i.e., completely deactivated.Furthermore, at least an interruption of the speed control is also possible by actuating the brake pedal, whereby an alternative design could also achieve complete deactivation by actuating the brake pedal.

[0021] The process begins in step 10 as soon as it is detected that the ACC system is active and the speed is being controlled automatically. If the cruise control system is active, the next step 20 checks whether the cruise control has been deactivated due to a control action by the driver. Deactivation here includes both switching off the cruise control and interrupting the cruise control.

[0022] If it is detected that the ACC system has been deactivated, the next step 30 checks whether the deactivation occurred due to the pressing of a dedicated button. In this example, deactivation would be detected if, while cruise control is active, the button designated for interrupting (pressing once) and deactivating (pressing twice) the cruise control is pressed only once, so that the active cruise control is merely interrupted. Alternatively, this query could also be answered with "yes" only after the button has been pressed twice, thus deactivating the cruise control.

[0023] If cruise control is deactivated using a button, the system proceeds to step 40 and switches to coasting mode SeM. This remains active as long as neither the accelerator pedal GP nor the brake pedal BP is depressed. If actuation of one of these two pedals GP or BP is detected in step 45, the system exits coasting mode SeM and switches to the familiar coasting mode SB with the corresponding coasting torque (step 50).

[0024] If no deactivation of cruise control via button is detected in step 30, it is assumed that deactivation occurred by pressing the brake pedal BP, since this type of deactivation is the only possible deactivation besides deactivation by pressing the corresponding button. In this case, the system switches directly to coasting mode SB (50).

Claims

[1] Method for activating a sailing mode in a motor vehicle, in which the kinetic energy of the motor vehicle is used to roll as far as possible without the drag torque of the engine braking the motor vehicle, wherein the engine can be switched to the sailing mode when an automatic cruise control is switched off, characterized by that the cruise control (ACC) can be deactivated completely or at least temporarily in at least two ways (button, BP) and, depending on the type of deactivation (button, BP), the cruise control (ACC) is switched to sailing mode (SeM) or to overrun mode (SB), in which the motor vehicle is braked by the drag torque of the engine. [2] Method according to claim 1, characterized bythat in sailing mode (SeM) the engine is separated from the drive train, whereby the separation of the engine from the drive train is advantageously carried out by an automatic actuation of the clutch or by an automatic engagement of the neutral gear. [3] Method according to claim 1 or 2, characterized by that in sailing mode (SeM) a zero torque is set on the drive train. [4] Method according to one of the preceding claims, characterized by that in sailing mode (SeM) a torque is set on the drive train whose generated generator power supports or ensures the power requirement of the drive engine and / or the requirement of the on-board network through the generator power of the drive engine. [5] Method according to one of the preceding claims, characterized bythat the cruise control (ACC) can be deactivated completely or at least temporarily by pressing a button (button) or by pressing the accelerator pedal or brake pedal (BP). [6] Method according to claim 5, characterized by that when the cruise control (ACC) is deactivated by pressing the button (button), the system switches to sailing mode (SeM) and when the cruise control (ACC) is deactivated by pressing the accelerator pedal or brake pedal (BP), the system switches to overrun mode (SB) at the latest after the accelerator pedal or brake pedal is released. [7] Method according to one of the preceding claims, characterized by that only when the cruise control (QACC) is completely deactivated does the system switch to sailing mode (SeM) and when it is temporarily deactivated does the system switch to overrun mode (SB). [8] Method according to one of the preceding claims, characterized bythat when the sailing mode (SeM) is active, the engine switches to overrun mode by pressing the accelerator pedal (GP) or brake pedal (BP). [9] Method according to one of the preceding claims, characterized by that the motor vehicle's engine is completely switched off in sailing mode (SeM).

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