Method for controlling an automatic transmission

Abstract

Method for controlling an automatic transmission by means of an electronic control unit (2) in a motor vehicle (1) during a spin-around, in which the motor vehicle (1) initially travels straight ahead at a vehicle speed (v) above a predetermined threshold or within a predetermined range with reverse gear (R) engaged and subsequently experiences a defined steering jerk (R_LW) which initiates a rotational movement, wherein, upon exceeding a defined rotational angle (S_DW), the automatic transmission is automatically switched from reverse gear (R) to the neutral position (N).

Description

[0001] The invention relates to a method for controlling an automatic transmission.

[0002] Automatic transmissions in motor vehicles have been known for many years. These transmissions are automatically controlled by an electronic control unit, particularly for selecting a specific gear. The driver is provided with a selector lever through which at least a reverse gear (R), a neutral position (N), and a forward driving position (D) can be manually pre-selected. The applicant has recently begun offering such automatic transmissions (BMW Steptronic) with an electronic selector lever. This invention is based on this technology.

[0003] For further information on the state of the art, please refer to DE 199 12 332 A1.

[0004] The purpose of the invention is to support the driver even in extreme driving situations.

[0005] This problem is solved according to the invention by the subject matter of independent claim 1. Dependent claims are advantageous embodiments of the invention.

[0006] The invention relates to a method for controlling an automatic transmission by means of an electronic control unit in a motor vehicle during a spin-around, in which the motor vehicle is initially traveling at a vehicle speed above a predetermined threshold (e.g., 20 km / h) or within a predetermined range (e.g., 20 km / h). <v<40km / h) bei eingelegtem Rückwärtsgang geradeaus fährt und anschließend einen definierten Lenkruck erfährt, durch den eine Drehbewegung (Driften) eingeleitet wird. Bei Überschreiten eines definierten Drehwinkels (z.B. 110°) wird das Automatikgetriebe automatisch vom Rückwärtsgang in die Neutralposition geschaltet.

[0007] Preferably, in a further development of the invention, upon detection of an end to the rotational movement (e.g. via the wheel speed sensors after reaching a maximum rotation angle of, for example, 180°), the automatic transmission is automatically switched from the neutral position to a forward driving position.

[0008] The invention is explained in more detail with reference to the drawing in the context of an exemplary embodiment. It shows a schematic representation of a driving situation in which the method according to the invention is used.

[0009] The drawing depicts a driving situation in which the driver of a motor vehicle 1 is traveling straight ahead in reverse (reverse gear R) at a vehicle speed v of approximately 30 km / h and, at time t0, abruptly turns the steering wheel, causing the vehicle to rotate approximately 180° around its own axis by time t2. During this driving situation, also known as a spin turn, the automatic transmission is automatically controlled, according to the invention, by a detection function in the control unit 2, independently of the driver's operation of the selector lever, from R through the neutral position N to the (forward) driving position D. This requires an electronic selector lever that does not involve any direct hydraulic intervention in the automatic transmission.

[0010] The detection function uses standard sensors (e.g., steering wheel angle sensor, wheel speed sensors, yaw angle sensor) to check, in particular, whether a predetermined minimum speed (e.g., 20 km / h) is reached during reverse driving, whether a steering jerk R_LW occurs, especially a short and relatively strong change in the steering angle LW, and whether a predetermined threshold S_DW is reached from the beginning of drifting due to the steering jerk R_LW.

[0011] The following section explains the individual steps in the depicted driving situation in more detail, based on the drawn curves over time t: 1. Starting from a starting position with a rotation angle DW of 0°, a motor vehicle 1 initially travels at a vehicle speed v above a predetermined threshold (e.g., 20 km / h) or within a predetermined range (e.g., 20 km / h). <v<40km / h) - hier mit 30 km / h - bei eingelegtem Rückwärtsgang R geradeaus. 2. At time t0, the driver generates a defined steering jerk R_LW, which initiates a rotational movement (drifting). 3. According to the invention, if a defined rotation angle S_DW (e.g. 110°) is exceeded, the automatic transmission is automatically switched from reverse gear R to neutral position N by means of the control unit 2. 4. When the end of the rotational movement is detected (e.g. via the wheel speed sensors after reaching a maximum rotation angle of, for example, 180°), the automatic transmission is automatically switched from the neutral position N to a forward driving position D.

[0012] This invention creates a safe and quick spin-around with a subsequent comfortable option for continuing the journey.

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