Pic. 7.17. Headlight auto leveling system: 1 - automatic leveling control unit (main); 2 - automatic leveling control unit (additional); 3 - front sensor of automatic leveling; 4 - rear automatic leveling sensor; 5 - headlight leveling actuator (left); 6 - headlight leveling actuator (right); 7 - ABS/TCS HU/CM or DSC HU/CM
The optical axis of the headlights are automatically set at certain angles to improve visibility and prevent dazzling drivers of oncoming vehicles when changing speed or vehicle load.
Pic. 7.18. Scheme of the automatic headlight leveling system when changing the vehicle load: 1 - setting to zero; 2 - increase in loading; 3 - automatic leveling control unit (main); 4 - automatic leveling control unit (additional); 5 - front automatic leveling sensor; 6 - rear automatic leveling sensor; 7 - headlight leveling actuator (left); 8 - headlight leveling actuator (right); 9 – ABS/TCS HU/CM or DSC HU/CM; 10 – difference between two voltage signals; 11 - the spatial position of the car; 12 – optical axis adjustment value; 13 – optical axis; 14 - the beginning of the countdown; 15 - high; 16 - low
Pic. 7.19. The scheme of the automatic headlight leveling system when the car is moving: 1 - setting to zero; 2 - acceleration; 3 - deceleration; 4 - automatic leveling control unit (main); 5 - automatic leveling control unit (additional); 6 - front automatic leveling sensor; 7 - rear automatic leveling sensor; 8 - headlight leveling actuator (left); 9 - headlight leveling actuator (right); 10 – ABS/TCS HU/CM or DSC HU/CM; 11 – difference between two voltage signals; 12 - the spatial position of the car; 13 - calculation of the acceleration angle; 14 - change in vehicle speed; 15 - the amount of adjustment of the optical axis; 16 - optical axis; 17 - the beginning of the countdown; 18 - high; 19 - low; 20 – vehicle speed; 21 - time
Work when changing the vehicle load
1. According to the vibrations of the suspension, the auto-leveling sensors installed in the front and rear of the car send a signal to the auto-leveling control unit (main).
2. When a difference is detected between the two signals of the auto leveling sensors, the auto leveling control unit (main) checks the height of the car, and then calculates the amount of adjustment of the optical axis and sends a signal to the automatic leveling control unit (additional).
3. The auto leveling control unit compares the actual and set position of the reflector and then outputs a control signal to the headlight leveling actuator.
Operation while driving
1. When driving with the headlights on, the automatic leveling control unit (main) receives a vehicle speed signal from the ABS/TCS HU/CM or DSC HU/CM unit and a signal based on suspension oscillations from the front and rear auto-levelling sensors.
2. Based on the vehicle speed signal, the auto leveling control unit calculates the acceleration angle and checks the change in vehicle speed. In addition, if there is a difference between the two signals of the front and rear auto level sensors, the auto level control unit (main) checks the actual position of the vehicle. The same unit calculates the amount of optical axis adjustment based on these two signals and outputs a signal to the automatic alignment control unit (additional).
3. The auto leveling control unit compares the actual and set position of the reflector and then outputs a control signal to the headlight leveling actuator.
Note. When the ignition switch is turned to the ON position, the sound of the headlight leveling actuator may be heard for a few seconds, this is normal as the system is being tested for operational condition.
When driving on a bad or uneven road, the auto leveling function would cause a flickering effect, resulting in dazzling oncoming drivers. To prevent this, the automatic headlight leveling is delayed.