Hill start assist

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Under a hill start assist or Berganfahrassistent refers to an automated support for motor vehicles when moving off on gradients, by rolling back is prevented. The driver does not need to operate the service or parking brake system. With this convenience function, the brake is first applied when starting and only released when the motor provides enough torque . Starting up on inclines is thus made much easier, especially in vehicles with manual transmissions .

Working principle

In today's vehicles, the anti-lock braking and ESP systems are networked with the engine control unit for hill start assistance . In addition, the hill start aid requires additional sensors , in particular a tilt sensor and, in the case of manual transmissions, a sensor for clutch actuation . Other sensors required, such as for the actuation of the brake pedal, are also required for other vehicle systems and are also used by the hill start aid.

In contrast to systems such as Auto Hold, the hill start assist can only lock in the brake pressure previously brought into the system by the driver. There is no active pressure build-up. If the vehicle is on an incline and all other conditions are met, e.g. B. The clutch is engaged, the correct gear (varies depending on the manufacturer) is engaged, the isolating valves of the anti-lock braking system are closed. If the driver releases the brake pedal to start moving, the brake pressure remains in the system. Rolling back of the vehicle is prevented. As soon as the driver steps on the accelerator again, the brake is released at a torque value for the engine set in the system's control unit. In most systems, the holding effect of the hill start aid is limited to a period of two to five seconds (depending on the system) in order to prevent misuse of the system as a parking brake. Furthermore, some systems are only activated with the appropriate combination of incline and gear selection: on a downhill slope and reverse gear engaged, or on inclines and reverse gear not engaged.

history

The original mechanism was invented by Studebaker in 1937 and used for the first time in the Studebaker President , later this so-called Hill Holder was only used in Subaru vehicles . In the meantime, however, numerous other automobile manufacturers also offer this function.

literature

  • Robert Bosch GmbH (editor): Automotive paperback . Vieweg Verlag, Wiesbaden 2007, ISBN 978-3-8348-0138-8 , 26th edition, page 864 f.