Fig. 7.17. Automatic headlight leveling system: 1 – Automatic alignment control unit (main); 2 – Automatic leveling control unit (additional); 3 – Front automatic leveling sensor; 4 – rear automatic leveling sensor; 5 – headlight alignment actuator (left); 6 – headlight alignment actuator (right); 7 – ABS/TCS HU/CM or DSC HU/CM
The optical axes of the headlights are automatically set at certain angles to improve visibility and prevent blinding oncoming drivers when the speed or load of the vehicle changes.
Fig. 7.18. Scheme of operation of the automatic headlight leveling system when the vehicle load changes: 1 - set to zero; 2 – increase in loading; 3 – Automatic alignment control unit (main); 4 – Automatic leveling control unit (additional); 5 – Front automatic leveling sensor; 6 – Rear automatic leveling sensor; 7 – headlight alignment actuator (left); 8 – headlight alignment actuator (right); 9 – ABS/TCS HU/CM or DSC HU/CM; 10 – the difference between two voltage signals; 11 – spatial position of the car; 12 – optical axis adjustment value; 13 – optical axis; 14 – start of counting; 15 - high; 16 - low
Fig. 7.19. Scheme of operation of the automatic headlight leveling system when the vehicle is moving: 1 - set to zero; 2 – acceleration; 3 - slow down; 4 – Automatic alignment control unit (main); 5 – Automatic alignment control unit (additional); 6 – Front automatic leveling sensor; 7 – Rear automatic leveling sensor; 8 – headlight alignment actuator (left); 9 – headlight alignment actuator (right); 10 – ABS/TCS HU/CM or DSC HU/CM; 11 – difference between two voltage signals; 12 – spatial position of the car; 13 – calculation of the acceleration angle; 14 – change in vehicle speed; 15 – optical axis adjustment value; 16 – optical axis; 17 – the beginning of the countdown; 18 - high; 19 - low; 20 – car speed; 21 – time
Operation when vehicle load changes
1. According to the vibration of the suspension, the automatic leveling sensors installed at the front and rear of the vehicle send a signal to the automatic leveling control unit (main).
2. When detecting a difference between the two auto-leveling sensor signals, the auto-leveling control unit (main) checks the vehicle height, and then calculates the optical axis adjustment amount and sends a signal to the auto-leveling control unit (additional).
3. The automatic leveling control unit compares the actual and set position of the reflector, and then outputs a control signal to the headlight leveling actuator.
Work while the vehicle is moving
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 and a suspension vibration signal from the front and rear automatic leveling sensors.
2. Based on the vehicle speed signal, the automatic 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 from the front and rear automatic leveling sensors, the automatic leveling control unit (main) checks the actual position of the vehicle. The same unit calculates the optical axis adjustment amount based on these two signals and outputs a signal to the automatic leveling control unit (additional).
3. The automatic 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 because the system operating mode is being checked.
When driving on a bad or uneven road, the automatic leveling function would cause a flickering effect, blinding oncoming drivers. To prevent this, the automatic leveling of the headlights occurs with delay.