Method for regulating the range of the headlights of a vehicle according to the load

#The invention relates to a method for regulating the range of the headlights of a vehicle according to the load.

#Regulation such as referred to here includes not only a static adjustment of the headlight range corresponding to the load state of the vehicle (cargo in the trunk, number of passengers, etc.), but also to a dynamic form of regulation in which the range is kept constant regardless of the pitching movements of the vehicle.

#Pitching of a vehicle around its transverse axis is a function of (among other things) vehicle speed, and at high speed frequently results in the front end of the car moving upward, with a corresponding change of the headlight range due to a corresponding reduction of the tilt of the headlights. Conversely, the tilt of the headlights is smaller at lower speeds since the vehicle then does not align itself or at least does so to a lesser degree. The inclination of the vehicle in the lengthwise direction depends on its geometry and spring characteristics, and can also depend for example on the level of the fuel in the tank and the air pressure in the tires.

#FIG. 1 is a schematic depiction of a headlight control arrangement for performing the method according to the invention.

#FIG. 2 is a graphic illustration of the manner of adjusting the headlight range of a vehicle as a function of vehicle speed according to the invention.

#Due to safety and comfort considerations, as well as legal requirements, the headlight range of a motor vehicle is basically adjustable within a certain range of tolerance. The invention utilizes this tolerance range to perform a deliberate change in headlight range as a function of vehicle speed. A prerequisite of this, and a feature of an advantageous embodiment of the invention, is to perform the entire adjustment of the headlight range within the tolerance range.

#FIG. 1 is a schematic illustration which shows an example of an apparatus for performing the method according to the invention. It includes a headlight unit 1, which is controlled by a headlight control unit 2 by adjusting the tilt of the headlights in the manner described previously. A speed sensor 3, which may detect vehicle speed in a conventional manner, provides an input signal to the control unit 2 for regulation of the headlight range according to the invention. (The sensor 3 may be, for example, a speed sensor which is otherwise already present on the vehicle as a part of a traction control system or ABS.) In addition, a sensor is provided to detect the road surface condition, and a signal is also input to the headlight control unit 2 from a suspension control unit 5.

#In FIG. 2 of the drawing, the dark columns form a bar graph which illustrates the adjustment of the headlight range as a function of speed, in a total of 5 steps from 50 to 75 meters, for representative speeds of 80, 100, 120, 140, 160, and 180 km/hour. The legally permitted tolerance range for a legally prescribed basic headlight setting of 55 meters is plotted as a gray column at the left edge of the graph. It comprises headlight ranges from 30 to 120 meters. The maximum value for the headlight range (120 meters) is about 65 meters above the legally prescribed value of 55 meters. For the assumed maximum set value of the headlight range of 75 meters, taking this tolerance into account, a maximum value for the headlight range is obtained that totals 140 (75+65) meters and still does not blind the oncoming traffic.