ramp control system HDC
HDC (Hill Descent Control): also referred to ramp the HDC control system, so that the driver can not be in complete control of the brake pedal, smooth by steep downhill slope segment. If necessary, the automatic control of each wheel braking device, in order to move slightly faster than the speed of forward travel, at this time the driver can fully concentrate on the control wheel.
HDC control system theory
HDC (Hill Descent Control) translated ldquo; Hill Descent Control rdquo ;, the name suggests, is to make the vehicle can be controlled in the case, through the steep road safety . The system first appeared in the 1997 Land Rover Freelander cars published, then extended use of signs on the same factory cars Discovery; BMW Land Rover worked behind the club in between 1994 and 2000, therefore, the technology used in this HDC BMW X5 car-based body. Principle
This HDC system is a combination of engine braking with anti-lock brakes cooperate ABS system, so that the vehicle is maintained at the next steep ldquo; low vehicle speed, but without loss of tire grip rdquo; state. HDC required shift position in the transmission case 1 or the reverse gear (the steep slope forward and reverse downhill slope, two) when the action of the system will be substantially set vehicle speed limit, Land Rover cars to an example, provided HDC after the vehicle speed upper limit set at 9 km / h, so that the driver can control the vehicle comfortably.
When HDC is set, after the vehicle enters the steep slopes engine braking may itself provide a degree of deceleration, the tire without the risk of locking. When the steep slope is too large, the engine brake will be insufficient to maintain the speed limit on the occasion, HDC will be able to by ABS system, the braking start point and release action, reduce the speed increasing, if necessary, to maintain a stable and safe speed downhill. If the driver during the next steep slope, it is necessary steering dodge obstacles, the HDC will sensing system, and further down to the upper limit vehicle speed 6.4 km / h, to ensure complete control of the vehicle.
It is noted that, where the ABS actuating system or not, but depending on the presence or absence of the vehicle speed exceeds the speed limit, and ABS anti-lock brake function is traditionally the driver braked, so that the lock of the tire death was the occasion to start is different.