Continental Automotive Systems USA - Hill Start Assist (HSA)

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Hill Start Assist (HSA)

HSA supports the driver during drive-off situations on steep slopes and improves the vehicle comfort in many everyday situations, such as stop-and-go traffic, at traffic lights or when parking. HSA is a convenient software enhancement for ESC* systems (Electronic Stability Control). When the driver releases the service brake, HSA prevents the vehicle from rolling back in the opposite direction. Driving off becomes safe and comfortable without having to use the parking brake.

After the driver has released the service brake, HSA retains the applied pressure in the brake system that is necessary for a complete standstill. During drive-off, HSA reduces the pressure in balance with the increasing driving torque. Functionality is achieved by controlling brake pressure under the following considerations:

Brake pressure applied by the driver
Transmission and engine information
Road inclination (longitudinal acceleration sensor)

1) The driver stops or holds the vehicle by using the service brake. The applied braking torque is sufficient to hold the vehicle at a complete standstill.

2) The vehicle stands still. The driver releases the brake pedal and starts to accelerate. HSA retains the braking pressure to ensure that there is no rolling back.

3) The vehicle is still standing. While the driver increases the driving torque, HSA reduces the pressure in balance to ensure, that there is neither rolling back nor drive-off against the brake.

4) The driving torque is sufficient to accelerate the vehicle forward. HSA has reduced the brake pressure to zero. The vehicle drives off.

HSA-functionality in combination with an electronic parking brake system (EPB or EHP)

For safety reasons, HSA can only function during drive-off. Free rolling of the vehicle is not permanently prevented. If the driver leaves the vehicle, the parking brake has to be applied as usual. However, if the vehicle is equipped with an electronic parking brake system, the EPB system would automatically activate for long term immobilization.

*ESC (Electronic Stability Control) = ESP (Electronic Stability Program)