Methods for aligning headlights

Abstract

The present invention relates to a method for aligning headlights (1) of a motor vehicle (2) having rear-axle steering (3), in which: - steerable rear wheels (4, 4a) of a rear axle (5) are moved into a service position in which they are symmetrically aligned to each other, - a line laser (6, 6a) is arranged on at least one wheel hub of the steerable rear wheels (4, 4a) of the motor vehicle (2), which projects a laser beam (7, 7a) forward parallel to a track of the associated rear wheel (4, 4a), - a light collection box (8) in the laser beam (7, 7a) is positioned in front of the motor vehicle (2), - an angle (α, β) between the laser beam (7, 7a) and a longitudinal axis of the vehicle (9) is determined, - the light collection box (8) is aligned according to the angle (α, β), - at least the one on the same side of the motor vehicle (2) as the associated line lasers (6, 6a) arranged headlights (1,1a) is set via the aligned light collecting box (8).

Description

The present invention relates to a method for aligning headlights of a motor vehicle having a rear axle steering system.DE 10 2004 026 044 B3 discloses a method and a system for checking the alignment of a radiation axis of a radar sensor on a motor vehicle. At least one reference laser source is arranged laterally on the motor vehicle with an alignment of the laser beam direction at right angles to the rear axle of the motor vehicle and facing forward. Furthermore, a measurement laser source is arranged on a reference surface of the radar sensor with an alignment of the laser beam direction parallel to the mirror axis of the radar sensor. The laser beams are imaged on measurement scales mounted in front of the motor vehicle on a measurement carriage that can be moved in the direction of the vehicle longitudinal axis, wherein the distances of the images of the laser beams on the measurement scales are recorded and compared at at least two different positions of the measurement carriage. This allows rapid and exact testing during re-manufacture and also during maintenance and repair work.WO 2008 / 002 973 A2 discloses a device for determining the orientation of a wheel arrangement, comprising a contact arrangement, a light source and a beam receiver arrangement. The contact assembly engages the wheel assembly to define an alignment plane of the wheel assembly. The light source, in turn, projects a light beam onto the contact assembly while the beam receiver assembly receives the light beam and generates an image of the light beam indicative of the orientation of the wheel assembly with respect to a predetermined position.DE 10 2019 004 918 A1 discloses a test station for setting components of a motor vehicle, having a first module which has a motor vehicle lift having at least four rotatable plates for respectively depositing a wheel of the motor vehicle on respectively one of the plates. Furthermore, a second module is provided, which has a wheel setting system for the wheels of the motor vehicle standing on the motor vehicle lift, and a third module, which has a headlight setting system for setting headlights of the motor vehicle standing on the motor vehicle lift. This is intended to minimize space requirements and also to minimize maneuvering effort.DE 10 2021 214 211 A1 discloses a device and a method for determining a chassis state of a vehicle. The apparatus comprises at least one optical detection device which is fastened to the vehicle and is designed to generate data based on optical detection of at least part of a chassis and of the vehicle. The apparatus further comprises a processing circuit configured to determine a position of the at least part of the chassis based on the data. The processing circuitry may also determine the chassis state of the vehicle based on the position of the at least a portion of the vehicle.From DE 10 2011 012 792 B3 a method for setting a direction of emission of a headlight of a vehicle having at least one front wheel and at least one rear wheel is known, comprising the following steps: detecting a front wheel angle of incidence of the at least one front wheel, detecting a rear wheel angle of incidence of the at least one rear wheel, establishing a direction of emission of the headlight as a function of the front wheel angle of incidence and the rear wheel angle of incidence, and setting the direction of emission of the headlight to the established direction of emission. As a result, an emission direction of a headlight should be able to be adapted even better to expected cornering.In general, in previous devices for adjusting a headlight on a motor vehicle with the aid of a light collection box, there is often the problem that the headlight does not illuminate parallel to the direction of travel. This problem is exacerbated if the rear wheels of the motor vehicle are not symmetrical to one another due to a rear steering function in the adjusted state of the headlights, since a systematic error then arises when determining a driving axis, after which the headlights are later adjusted.The present invention is therefore concerned with the problem of specifying a method for aligning headlights of a motor vehicle having a rear axle steering system, in which method the disadvantages known from the prior art can be overcome.This problem is solved according to the invention by the subject matter of independent claim 1. Advantageous embodiments are the subject of the dependent claims.The present invention is based on the general idea of including tracks of rear wheels of a motor vehicle having a rear axle steering system in an adjustment of headlights of the motor vehicle. Specifically, this means that a track of the rear wheels is determined by means of a line laser, on the basis of which the headlights of the motor vehicle are aligned. In the method according to the invention, steerable rear wheels of a rear axle are thus initially adjusted into a service position in which they are aligned symmetrically with respect to one another. "Symmetrical" can mean in this case either parallel or with toe-in or toe-out. In the case of a toe-in, the two laser beams projected by the two line lasers onto the light collection box situated in front of the motor vehicle are closer to one another than in the case of a toe-in. The steerable rear wheels can be adjusted into the service position via a steering device which is already present for steering the steerable rear wheels. Subsequently or before, a line laser is arranged on at least one wheel hub of the steerable rear wheels of the motor vehicle, said line laser projecting a laser beam forward parallel to a track of the associated rear wheel. Specifically, this means that a first line laser is arranged at least on a left rear wheel of the motor vehicle or a second line laser is arranged on an opposite right rear wheel of the motor vehicle. The at least one line laser then casts a laser beam in the manner of a laser line in front of the motor vehicle, wherein the laser beam approaches a vehicle center axis forward when the associated rear wheel is toe-in and leads away from the associated rear wheel when the associated rear wheel is toe-in. A light collection box is then positioned in the laser beam in front of the motor vehicle and an angle α, β between the laser beam and a vehicle longitudinal axis is determined.The light collecting box is again subsequently aligned according to the angle α, β, wherein at least the headlight arranged on the same side of the motor vehicle as the associated line laser is adjusted via the aligned light collecting box. This makes it possible to adjust the headlights extremely simply and exactly depending on the track of the rear wheels of the rear axle, in particular if such a motor vehicle has a rear axle steering system.Due to the fact that the two steered rear wheels are set symmetrically to one another in the service position, both headlights can also be set via only one line laser by means of the determined angle between the laser beam and the vehicle longitudinal axis.It is also conceivable that a line laser is arranged on each of the two wheel hubs of the steerable rear wheels of the motor vehicle, which line laser project a respective laser beam forward parallel to a track of the respective rear wheel. The light collecting box is then first positioned in one of the two laser beams in front of the motor vehicle. The position is defined by measurement rules for setting and checking the headlights. An angle α between the laser beam and the vehicle longitudinal axis is again subsequently determined, wherein the light collecting box is then aligned corresponding to the angle α. The headlamp, which is arranged on the same side of the motor vehicle as the associated line laser, is then adjusted via the aligned light collecting box. The light collecting box is now displaced until it reaches the other of the two laser beams in front of the motor vehicle. An angle β between the laser beam of the other line laser and the vehicle longitudinal axis is then also determined here, wherein again the headlight arranged on the same side of the motor vehicle as the other line laser is subsequently adjusted via the aligned light collection box. In this case, line lasers are thus mounted on both wheel hubs and both tracks of the rear wheels are included in the adjustment of the headlights. This makes it possible to compensate for possibly symmetry inaccuracies occurring in the service position between the two rear wheels.It is also conceivable that before the two headlights are adjusted, the two angles α, β determined between the two laser beams and the vehicle longitudinal axis are averaged and, on the basis of this averaged angle, the light collection box and, above this, the two headlights are aligned. This is effected as follows: Firstly, a line laser is arranged on each of the two wheel hubs of the steerable rear wheels of the motor vehicle, said line laser projecting an associated laser beam forward parallel to a track of the associated rear wheel, after which the light collection box is first positioned in front of the motor vehicle in the laser beam of the one line laser. An angle α between the laser beam of the one line laser and the vehicle longitudinal axis is then determined. The light collecting box is then positioned in front of the motor vehicle in the laser beam of the other line laser, wherein an angle β between the laser beam of the other line laser and the vehicle longitudinal axis is determined. The two angles α, β are now averaged and the light collecting box is aligned corresponding to this averaged angle. Finally, both headlights are adjusted via the aligned light collection box.Expediently, the steerable rear wheels of the rear axle are set in the service position at an angle of 0° to the vehicle longitudinal axis. This has the great advantage that in this case only a single line laser has to be arranged on an associated wheel hub in order to adjust or test the two headlights. As a result, the setting can be effected much more quickly and more economically.Regardless of the track of the rear wheels of the motor vehicle, the method according to the invention can achieve a reliable setting of the headlights, which setting takes into account an overall track of the motor vehicle. If the headlights are only aligned at vehicle body points, then in the case of an overall lane of the motor vehicle deviating from a vehicle longitudinal direction, the headlights would not illuminate, or only partially illuminate, the roadway lying in front of the motor vehicle.The symmetrical setting of the rear wheels of the rear axle with respect to one another can also take place, for example, already when the ignition is switched off or else temporarily when the service position is requested.Further important features and advantages of the invention are evident from the dependent claims, from the drawings and from the associated description of the figures with reference to the drawings.It is understood that the features mentioned above and those still to be explained below can be used not only in the respectively specified combination, but also in other combinations or alone, without departing from the scope of the invention as defined by the claims. The above-mentioned components of a superordinate unit, such as a device, a device or an arrangement, which are designated separately, can form separate components or components of this unit or can be integral regions or sections of this unit, even if this is illustrated differently in the drawings.Preferred exemplary embodiments of the invention are illustrated in the drawings and are explained in more detail in the following description, wherein the same reference numerals refer to the same or similar or functionally the same components.They show, in each case schematically, FIG. 1 shows a conventional motor vehicle with headlights oriented to a body axis, FIG. 2 shows a motor vehicle with headlights oriented according to a method according to the invention, FIG. 3 shows a motor vehicle with line lasers attached to it for the purpose of illustrating the method according to the invention.According to FIGS. 2 and 3, in a method according to the invention for aligning headlights 1, 1 aof a motor vehicle 2 having a rear axle steering 3, steerable rear wheels 4, 4 aof a rear axle 5 are initially transferred into a service position in which the rear wheels 4, 4 aare set symmetrically to one another, that is to say symmetrically to a vehicle longitudinal axis 9. Such a symmetrical adjustment of the rear wheels 4 can be effected, for example, in the manner of toe-in, as is illustrated in accordance with FIG. 3, in parallel or in the manner of toe-in. The adjustment is effected via a steering device which is already present for steering the rear wheels. Before or subsequently, a line laser 6, 6 ais arranged on at least one wheel hub of the steerable rear wheels 4, 4 aof the rear axle 5, said line laser projecting a laser beam 7, 7 atowards the front parallel to a track of the associated rear wheel 4, 4 aon a light collection box 8 lying in front of the motor vehicle 2. The light collection box 8 is then positioned in the laser beam 7, 7 ain front of the motor vehicle 2 and an angle α, β between the laser beam 7, 7 aand the vehicle longitudinal axis 9 is determined. The light collecting box 8 is then aligned according to the angle α, β, wherein at least the headlight 1, 1 aarranged on the same side of the motor vehicle 2 as the associated line laser 6, 6 ais adjusted via the aligned light collecting box 8. In FIG. 3, auxiliary lines 10, 10a are drawn which run parallel to the vehicle longitudinal axis 9 and which serve for simplified representation of the angles α, β.With the method according to the invention, it is thus easily possible to align the emission direction of the headlights 1, 1 ain the direction of travel 12 and thus parallel to the entire lane of the motor vehicle 2, thereby preventing these headlights, as would be the case with an alignment set parallel to the vehicle longitudinal axis 9, from illuminating beyond a roadway 11 and thus not illuminating the actual roadway 11 or at least not sufficiently illuminating.In order to be able to compensate for symmetry inaccuracies occurring between the two rear wheels 4, 4 a, in particular in the service position, a line laser 6, 6 acan also be arranged on each of the two wheel hubs of the steerable rear wheels 4, 4 aof the motor vehicle 2, which line lasers project a respective associated laser beam 7, 7 atoward the front parallel to a track of the respective rear wheel 4, 4 a. In this case, the light collection box 8 is first positioned in the laser beam 7 of the one line laser 6 in front of the motor vehicle 2, wherein an angle α between the laser beam 7 of the one line laser 6 and the vehicle longitudinal axis 9 is determined. Subsequently, the light collecting box 8 is aligned according to the angle α, and the headlight 1 arranged on the same side of the motor vehicle 2 as the associated line laser 6 is adjusted via the aligned light collecting box 8. The light collection box 8 is now positioned in the laser beam 7 aof the other line laser 6 ain front of the motor vehicle 2 and an angle β is determined between the laser beam 7 aof the other line laser 6 aand the vehicle longitudinal axis 9. Finally, the headlight 1a arranged on the same side of the motor vehicle 2 as the other line laser 6a is adjusted via the aligned light collecting box 8. In this case, line lasers 6, 6a are thus mounted on both wheel hubs and both tracks of the rear wheels 4, 4a are included in the setting of the headlights 1, 1a.It is also conceivable that before the setting of the two headlights 1, 1 a, the two angles α, β determined between the two laser beams 7, 7 aand the vehicle longitudinal axis 9 are averaged and the light collection box 8 and both headlights 1, 1 aare aligned on the basis of this averaged angle.It is particularly favorable if the steerable rear wheels 4, 4 aof the rear axle are adjusted in the service position to an angle α, β of 0° with respect to the vehicle longitudinal axis 9. This has the great advantage that in this case only a single line laser 6, 6 amust be arranged on an associated wheel hub in order to adjust or test the two headlights 1, 1 a. As a result, the setting can be effected much more quickly and more economically.If, on the other hand, a motor vehicle 2' which does not fall under the invention is considered according to FIG. 1, it can be seen there that the headlights 1', 1a' do not compensate for the deviation between a direction of travel 12' and a vehicle longitudinal axis 9' and as a result illuminate to the right beyond the roadway 11'. In FIG. 1, the same reference numerals are used, with apostrophe only.All in all, errors as would occur, for example, in a classic setting of headlights 1, 1 awith a light collection box 8 can be reliably avoided with the method according to the invention, since in this case the lanes of steerable rear wheels 4, 4 aof a motor vehicle 2 having a rear axle steering 3 are not taken into account. Furthermore, the headlights 1, 1 acan be adjusted comparatively easily and extremely exactly using the method according to the invention. If the headlights 1, 1 awere only aligned at vehicle body points, then in the case of an overall lane of the motor vehicle 2 deviating from the vehicle longitudinal direction 9, the headlights 1, 1 awill not illuminate, or only partially illuminate, the roadway 11 lying in front of the motor vehicle 2 in the direction of travel 12.

Claims

Method for aligning headlights (1, 1a) of a motor vehicle (2) having a rear-axle steering system (3), in which - steerable rear wheels (4, 4a) of a rear axle (5) are adjusted into a service position in which they are aligned symmetrically with respect to one another, - a line laser (6, 6a) is arranged on at least one wheel hub of the steerable rear wheels (4, 4a) of the motor vehicle (2), said line laser projecting a laser beam (7, 7a) forward parallel to a track of the associated rear wheel (4, 4a), - a light collecting box (8) is positioned in the laser beam (7, 7a) in front of the motor vehicle (2), - an angle (α, β) between the laser beam (7, 7a) and a vehicle longitudinal axis (9) is determined, - the light collecting box (8) is aligned according to the angle (α, β), at least the headlight (1, 1a) arranged on the same side of the motor vehicle (2) as the associated line laser (6, 6a) is adjusted via the aligned light collection box (8).Method according to Claim 1, characterized - in that a line laser (6, 6a) is arranged in each case on both wheel hubs of the steerable rear wheels (4, 4a) of the motor vehicle (2), said line laser projecting an associated laser beam (7, 7a) forwards parallel to a track of the associated rear wheel (4, 4a), - in that the light collecting box (8) is first positioned in front of the motor vehicle (2) in the laser beam (7) of the one line laser (6), - in that an angle (α) between the laser beam (7) of the one line laser (6) and the vehicle longitudinal axis (9) is determined, - in that the light collecting box (8) is aligned in accordance with the angle (α), - in that the headlight (1) arranged on the same side of the motor vehicle (2) as the associated one line laser (6) is adjusted via the aligned light collecting box (8), the light collecting box (8) is then positioned in the laser beam (7a) of the other line laser (6a) in front of the motor vehicle (2), an angle (β) is determined between the laser beam (7a) of the other line laser (6a) and the vehicle longitudinal axis (9), the light collecting box (8) is aligned according to the angle (β), the headlight (1a) arranged on the same side of the motor vehicle (2) as the other line laser (6a) is adjusted via the aligned light collecting box (8).Method according to Claim 1, characterized - in that a line laser (6, 6a) is arranged in each case on both wheel hubs of the steerable rear wheels (4, 4a) of the motor vehicle (2), said line laser projecting an associated laser beam (7, 7a) forwards parallel to a track of the associated rear wheel (4, 4a), - in that the light collecting box (8) is first positioned in front of the motor vehicle (2) in the laser beam (7) of the one line laser (6), - in that an angle (α) between the laser beam (7) of the one line laser (6) and the vehicle longitudinal axis (9) is determined, - in that the light collecting box (8) is then positioned in front of the motor vehicle (2) in the laser beam (7a) of the other line laser (6a), an angle (β) between the laser beam (7a) of the other line laser (6a) and the longitudinal axis (9) of the vehicle is determined, the two angles (α, β) are averaged, the light collecting box (8) is aligned according to the averaged angle, the two headlights (1, 1a) are adjusted via the aligned light collecting box (8).Method according to one of the preceding claims, characterized in that the steerable rear wheels (4, 4a) of the rear axle (5) are adjusted in the service position into an angle (α, β) of 0° with respect to the vehicle longitudinal axis (9).Method according to one of the preceding claims, characterized in that the steerable rear wheels (4, 4a) of the rear axle (5) are automatically adjusted into the service position when the motor vehicle (2) is shut off.

Images