1. Introduction
the 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 as “Hill Descent Control”, by definition, in the case of the vehicles it can be controlled, 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 brake cooperates with ABS anti-lock braking system, so that the vehicle maintains the state “low speed without loss of tire grip” when the next steep slope. 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, without the danger of locking the tire. 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 the ABS system, if necessary, start braking point and release action, reduce the speed increasing 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 onWhether the vehicle speed exceeds the speed limit, and ABS anti-lock braking function is traditionally the driver braked, so that the tire was locked on the occasion of start it is different.
2, release all the pedal autopilot
before entering the HDC system must be set up on the steep road, the steering wheel so that the owner can fully process. Due to the steep road, any improper pedal operation could lead to dangerous loss of control, such as the brakes will make tires locked slip, the clutch will lose engine braking and so on. So after the HDC button is set, the driver should release all pedals, throttle, brake and clutch manual transmission vehicles will include effective actuation. This way of driving, I believe many people will feel when the first experience of the field trip.