Method for calibrating the beam range of a vehicle headlight and motor vehicle

Abstract

The present invention is based on the general idea of ​​providing a method for calibrating the range of a vehicle headlight when a reference run is aborted and for detecting, by means of a headlight control unit, whether the sensorless stepper motor is in a stressed position, for example, whether it has moved against an end stop, and if so, moving the sensorless stepper motor into a stress-free position in order to avoid mechanical defects.

Description

[0001] The present invention relates to a method for calibrating the beam range of a vehicle headlight. The invention further relates to a motor vehicle comprising a headlight and a headlight control unit for carrying out this method.

[0002] From DE 10 2004 008 063 B4, a method for controlling an electronic stepper motor to vary the characteristics of a light beam emitted by a motor vehicle headlight is known. Depending on the desired characteristic of the light beam, a target current value is specified for the stepper motor, and the motor is controlled accordingly. Subsequently, based on the target current value, a target value for the mechanical position of a rotor of the stepper motor is determined, and an actual value of the rotor's mechanical position is recorded. This actual value is compared with the target value of the rotor's mechanical position. To determine the actual value of the rotor's mechanical position, the time course of an actual current value of the stepper motor is recorded and evaluated.

[0003] From DE 103 31 869 A1, a method for calibrating a vehicle headlight is known, the light emission direction of which is swivelable and in which the light emission direction is swivelled in a reference run to calibrate the swivel angle. The calibration of the swivel angle is carried out depending on a driving situation.

[0004] From DE 10 2017 112 514 A1, a further method for calibrating at least one headlight of a vehicle is known, which provides images of the light field generated by the at least one headlight in various positions and determines calibration values ​​by evaluating the provided images of the light field. Simultaneously, the calibration values ​​are transmitted to a headlight control unit for controlling the at least one headlight. At the beginning of the method, the status of conditions from a first group and the status of conditions from a second group are checked hierarchically according to their group affiliation, and subsequently, the status of all conditions is checked jointly and uniformly. The method is terminated if any of these conditions is not met.

[0005] From DE 10 2020 129 824 B3, a method for operating a motor vehicle is known, comprising a headlight with a projection module that is moved by a motor into a projection position to regulate the headlight's beam range. The motor for moving the projection module is controlled to the projection position to approach a setpoint motor speed, the setpoint motor speed being stored in a non-volatile memory of the headlight. Upon switching on the headlight's power supply following a power outage, the projection module moves from the stored setpoint motor speed to a leaving-home position to illuminate the area adjacent to the motor vehicle. This is intended, in particular, to prevent inadvertently reaching end stops and the associated mechanical damage.

[0006] From DE 103 51 795 A1, a method for operating a vehicle headlight is known, the light emission direction of which is pivotable and which has at least two switches arranged around the straight-ahead orientation of the light beam for detecting the pivot position of the optical device and a control unit with a memory. To initialize the vehicle headlight, the light emission direction of the vehicle headlight is pivoted from the straight-ahead position until one switch changes its state, whereby the pivot angle at which the switch changes its state is stored. The light emission direction is then pivoted in the opposite direction until the other switch changes its state, whereby the pivot angle is also stored during this change of state.This should make it possible to quickly perform an initial initialization of the headlight, while simultaneously capturing tolerances in the positioning of the switches.

[0007] To compensate for changes in the position of the headlight range adjustment mechanism in parked vehicles, an electric motor (stepper motor) is rereferenced before driving begins. This rereference process is initiated by starting the engine (internal combustion engine), the vehicle being ready to drive (electric vehicles), or turning the ignition "ON" (hood open) and takes approximately 3 seconds. However, if the ignition is switched off within this timeframe, the rereference is aborted, and the stepper motor remains in its current position. Because the rereference process is sensorless, the stepper motor is held at a mechanical stop for a certain period. Therefore, there is a high probability that the stepper motor will be in this position when the rereference is aborted, which can lead to stress in the mechanical system and, in the long term, to a mechanical failure of the headlight range adjustment mechanism.

[0008] The present invention therefore deals with the problem of providing a method for calibrating the beam range of a vehicle headlight, by means of which in particular the problems known from the prior art can be overcome.

[0009] This problem is solved according to the invention by the subject matter of independent claim 1. Advantageous embodiments are the subject matter of the dependent claims.

[0010] The present invention is based on the general concept of providing a method for calibrating the beam range of a vehicle headlight when a reference run is aborted, and for using a headlight control unit to detect whether the sensorless stepper motor is in a stressed position, for example, having reached an end stop, and if so, to move the sensorless stepper motor into a stress-free position in order to prevent mechanical defects. In the inventive method for calibrating the beam range of a vehicle headlight, the aforementioned headlight control unit controls a stepper motor of the vehicle headlight to adjust the beam range. To calibrate the stepper motor and thus the beam range of the vehicle headlight, the headlight control unit adjusts / moves the sensorless stepper motor in a reference run within a predetermined reference runtime t.RefLauf from an upper maximum position X MaxPosOben to a lower minimum position X MinPosUnten The headlight control unit, in turn, adjusts the stepper motor after reaching the lower minimum position X. MinPosUnten within a predefined time t PosSicher into a safety position X MinPosSicher and via these into a target position X SollPos .

[0011] In the event that the reference run occurs at a position between the upper maximum position X MaxPosOben and lower minimum position X MinPosUnten Current position X IstPosVorRef starts and the reference run terminates at a time t Abbruch If the process is aborted, the headlight control unit checks when the abort occurred and a) in the case that t Abbruch < t RefLauf The headlight control unit always moves the stepper motor by a delta distance X. MinPosSicher - X MinPosunten up, b) in the case that t PosSich > t Abbruch > t RefLaufThe headlight control unit moves the stepper motor to at least the fuse position X. MinPosSicher up, c) in the case that t PosSicher ≤ t Abbruch the headlight control unit does not move the stepper motor.

[0012] This ensures that the stepper motor does not move against the lower minimum position X. MinPosUnten , i.e., it is mechanically pre-tensioned against a lower end stop and remains there, thereby suffering damage, especially in the long term. This makes it possible to specify a method for calibrating a stepper motor and thus the beam range of a vehicle headlight, in which the disadvantages known from the prior art, namely in particular the remaining and thus the tension against an end stop, which can lead to mechanical damage in the long term, can be avoided.

[0013] If the reference run is therefore interrupted, for example by switching off the ignition, before the reference runtime t has elapsed, RefLauf If the reference run has expired, it can be assumed that if the reference run does not reach the upper maximum position X MaxPosOben , but at one between the upper maximum position X MaxPosOben and the lower minimum position X MinPosUnten Current position X IstPosVorRef The stepper motor was started at the lower minimum position X. MinPosUnten is in contact with and biased against this when the ignition is switched off, i.e., when the reference run is aborted. In this position, the stepper motor has the locking position X. MinPosSicher , in which there is no mechanical stress, has not yet been achieved.

[0014] In this case, the control unit therefore checks when the abort occurred and makes further decisions on a case-by-case basis: By adjusting / moving the sensorless stepper motor by a delta distance XMinPosSicher - X MinPosunten upwards, for case a), where: t Abbruch < t RefLauf This can relieve tension and thus reliably prevent mechanical damage to the stepper motor, especially in the long term.

[0015] In case b), for which t PosSich > t Abbruch > t RefLauf If this is the case, the headlight control unit moves the stepper motor to at least the safety position X. MinPosSicher upwards. This means the reference run is aborted before the stepper motor reaches the safety position X. MinPosSicher after reaching or exceeding the lower minimum position X MinPosUnten Once this has been achieved, the remaining process / adjustment of the stepper motor is carried out by means of the method according to the invention, at least in the direction of the locking position X. MinPosSicher This safety position X MinPosSicher is so far from the lower minimum position X MinPosUntenspaced so that it can be reliably ruled out that the stepper motor remains in a state of tension and thus in a position that could cause long-term mechanical damage.

[0016] In case c), for which t PosSicher ≤ t Abbruch If this is the case, the headlight control unit does not adjust / move the stepper motor. In this case, the stepper motor has enough time, namely at least t. PosSicher , in which the safety position X MinPosSicher The target position is reliably reached before the reference run is aborted. Therefore, no further adjustment of the stepper motor is necessary, as it is already in a relaxed position, even if the stepper motor has moved beyond its actual target position X. SollPos has not yet been achieved.

[0017] The present invention is further based on the general concept of providing a motor vehicle with a headlight having a beam range adjustable by means of a sensorless stepper motor and with a headlight control unit, wherein the headlight control unit is configured to carry out the method described in the preceding paragraphs. This allows the advantages described with respect to the method according to the invention to be transferred to the motor vehicle according to the invention. Specifically, these advantages lie in the ability to hold the sensorless stepper motor in a non-stressed position, or to move it into a non-stressed position, even if the reference run is aborted. This reliably prevents damage to the stepper motor caused by unwanted stress, i.e., for example, by running against an end stop.

[0018] Ideally, the vehicle headlight should be a front headlight. Motor vehicles can be tilted at different angles due to varying loads, making headlight range adjustment particularly advantageous. This effect is further enhanced if the vehicle is equipped with a trailer hitch, allowing additional weight to be added to the rear. Headlight range adjustment, especially automatic headlight range adjustment, is particularly beneficial for such vehicles, and the method according to the invention contributes to maintaining reliable headlight range adjustment over the long term.

[0019] Further important features and advantages of the invention will become apparent from the dependent claims, the drawings and the associated description of the figures based on the drawings.

[0020] It is understood that the features mentioned above and those to be explained below can be used not only in the combinations specified, but also in other combinations or individually, without departing from the scope of the invention as defined by the claims. Components of a higher-level unit, such as a device, apparatus, or arrangement, mentioned above and those to be mentioned below, which are designated separately, can form separate parts or components of this unit or be integral areas or sections of this unit, even if this is depicted differently in the drawings.

[0021] Preferred embodiments of the invention are shown in the drawings and are explained in more detail in the following description, wherein identical reference numerals refer to identical or similar or functionally identical components.

[0022] They show, schematically, Fig. 1 Individual process steps of a method according to the invention for calibrating the beam range of a vehicle headlight, Fig. 2 a motor vehicle according to the invention with a vehicle headlight and a headlight control unit, which is designed to carry out the method according to the invention, Fig. 3. A beam range-time diagram for comparing an optimal reference run and a practical example of a reference run. Fig. 4 a beam range-time diagram in which a reference run is prematurely terminated, Fig. 5 a representation similar to in Fig. 3, in which, however, the reference run is interrupted after exceeding a reference runtime t RefLauf and before reaching a secure position X MinPosSicher is cancelled Fig. 6 a representation analogous to Fig. 5, in which, however, the reference run is aborted after reaching the safety position X MinPosSicher This has been done.

[0023] According to the Fig. 1 is used in a method according to the invention for calibrating a beam range LW of a vehicle headlight 1 (compare Fig. 2) or, in order to calibrate a stepper motor 4 of a motor vehicle 2 according to the invention, in a process step A, a stepper motor 4 is first controlled to adjust the headlight range LW by means of a headlight control unit 3.

[0024] In process step B, the headlight control unit 3 adjusts / moves the stepper motor 4 to calibrate the headlight range LW in a reference run within a reference runtime t. RefLauf from an upper maximum position X MaxPosOben to a lower minimum position X MinPosUnten .

[0025] In process step C, the headlight control unit 3 adjusts the sensorless stepper motor 4 after reaching the lower minimum position X. MinPosUnten within a predefined time t PosSicher into a safety position X MinPosSicher and via these into a target position X SollPos .

[0026] In the subsequent process step D, the headlight control unit 3 checks in case the reference run is not at the upper maximum position X. MaxPosOben , but at one between the upper maximum position X MaxPosOben the lower minimum position X MinPosUnten Current position X IstPosVorRef starts (compare Fig. 3, line with circles) and the reference run at a termination time t Abbruch is cancelled (see above). Fig. 4 - 6), when exactly the abort occurred and whether at that time the stepper motor 4, which is above the lower minimum position X MinPosUnten lying safety position X MinPosSicher has achieved it or not.

[0027] In process step E, the headlight control unit 3 distinguishes the following three sub-cases a) to c) and: a) moves the stepper motor 4 in the case that t Abbruch < t RefLauf always by a delta distance X MinPosSicher - X MinPosunten up, b) moves the stepper motor 4 in the case that t PosSich > t Abbruch > t RefLauf at least to the safety position X MinPosSicher up, c) does not move the stepper motor 4 in the case that t PosSicher ≤ t Abbruch .

[0028] This prevents the stepper motor 4 from moving towards the lower minimum position X if the reference run is prematurely terminated, for example by switching off the ignition. MinPosUnten , for example, a lower end stop, remains in a pre-tensioned position and thus suffers long-term mechanical damage.

[0029] If one considers the Fig. 3, one can see from the upper line marked with crosses that the reference run at time t0 is usually at the upper maximum position X MaxPosOben begins and after the reference runtime t has elapsed RefLauf the lower minimum position X MinPosUnten The stepper motor 4 is then controlled by the headlight control unit 3 so that the stepper motor 4 reaches the target position X. SollPos This is achieved. This represents the optimal reference run.

[0030] During the reference run, the headlight control unit 3 always assumes that the electric motor or the stepper motor 4 is at the upper maximum position X. MaxPosOben It is located there and also starts there. In reality, however, stepper motor 4 does not always point to the upper maximum position X at the beginning of the reference run. MaxPosOben on, but often one between the upper maximum position X MaxPosOben and a lower minimum position X MinPosUnten Current position X IstPosVorRefThe line marked with circles in the Fig. 3 represents starting the reference run at such an actual position X IstPosVorRef This means the reference run starts at the actual position X. IstPosVorRef , so the stepper motor 4 or the lighting range adjusted by the stepper motor 4 reaches the lower minimum position X MinPosUnten even before reaching the reference runtime t RefLauf , for example at time t1, and remains there until the end of the reference runtime t RefLauf , in order to then return to the top via the safety position X MinPosSicher (compare Fig. 4) into the target position X SollPos to be adjustable.

[0031] If the reference run is aborted at an abort time t Abbruch , in which the stepper motor 4 is at the lower minimum position X MinPosUnten If this occurs, the stepper motor 4 is tensioned against the lower minimum position X. MinPosUnten, which can cause long-term damage to stepper motor 4.

[0032] If one considers the Fig. 4, it can be seen that the termination of the reference run at a termination time t Abbruch a duration that is smaller than the reference runtime t RefLauf and is also smaller than a time t PosSicher to reach a secure position X MinPosSicher , which are between the lower minimum position X MinPosUnten and the target position X SollPos The reference run is therefore aborted before stepper motor 4 reaches the position above the lower minimum position X. MinPosUnten lying safety position X MinPosSicher has reached, whereupon the headlight control unit 3 moves the stepper motor 4 by a delta distance X using the method according to the invention, as described in subcase a). MinPosSicher - X MinPosuntenupwards and thus into a tensionless state in which the stepper motor 4 is not mechanically pre-tensioned and can therefore be damaged.

[0033] In the Fig. In the case shown in section 4, the headlight control unit 3 can also move the sensorless stepper motor 4 into the safety position X. MinPosSicher adjust after the reference run is aborted. At the time of abort t Abbruch Although stepper motor 4 is no longer at the lower minimum position X MinPosUnten and therefore cannot be mechanically tensioned, nevertheless, the specified locking position X can MinPosSicher A position can be reached in which the risk of tension is further reduced.

[0034] If one considers the Fig. 5, so it can be seen there that the reference run is again at the actual position X IstPosVorRef starts and the reference run is aborted at a termination time t AbbruchThis occurs after the reference runtime t RefLauf , but before the predefined time t PosSicher is located at which the safety position X MinPosSicher has not yet been reached (t RefLauf < t Abbruch < t PosSicher In this sub-case b), the headlight control unit 3 adjusts the stepper motor 4 after reaching the lower minimum position X. MinPosUnten within a predefined time t PosSicher at least to the safety position X MinPosSicher , which according to the Fig. 5 has not yet been reached.

[0035] If one considers the Fig. 6, so it can be seen that the reference run is again at the actual position X IstPosVorRef begins and the headlight control unit 3 drives the sensorless stepper motor 4 to the lower minimum position X MinPosUnten adjusted and remains there until the reference runtime t RefLaufThe timer has expired. The headlight control unit 3 then adjusts the stepper motor 4 towards the target position X. SollPos , whereby according to the Fig. 6. A termination of the reference run, i.e., a termination before reaching the target position X. SollPos , but after exceeding the safety position X MinPosSicher This occurs, so that in this case the headlight control unit 3 is at the abort time t Abbruch the stepper motor 4 is not adjusted further, as it is at this abort time t Abbruch the target position X SollPos although it has not yet reached the safety position X MinPosSicher , in which no mechanical damage to the stepper motor 4 is to be feared.

[0036] In Fig. For clarification, sub-cases a), b) and c) are highlighted again in section 6, which are analogous to sub-cases a), b) and c) listed in procedure step E.

[0037] In the illustrated sub-case a) (see also Fig. 4), in which t Abbruch < t RefLauf If this applies, the headlight control unit 3 always moves the stepper motor 4 by a delta distance X. MinPosSicher - X MinPosunten up.

[0038] In the illustrated sub-case b) (see also Fig. 5), in which t PosSich > t Abbruch > t RefLauf If this applies, the headlight control unit 3 moves the stepper motor 4 to at least the fuse position X. MinPosSicher up.

[0039] In the illustrated sub-case c) (compare Fig. 6), in which t PosSicher ≤ t Abbruch If this is the case, the headlight control unit 3 does not move the stepper motor 4, since in this case the stepper motor 4 has sufficient time, namely at least t PosSicher , in which he secured position X MinPosSicherhas reliably reached its target position X before the reference run is aborted. In this position, no further adjustment of stepper motor 4 is necessary, as it is already in a relaxed position, even though stepper motor 4 has reached its actual target position X. SollPos has not yet been achieved.

[0040] By means of the method according to the invention, the stepper motor 4 can thus be operated independently of its starting actual position X. IstPosVorRef calibrated, whereby at the same time no mechanical damage occurs in the event of an interruption of the reference run, for example due to clamping against the lower minimum position X. MinPosUnten This should be avoided. This will ensure a long-term, flawlessly functioning headlight range control system.

Claims

[1] Method for calibrating the beam range (LW) of a vehicle headlight (1), wherein - a headlight control unit (3) controls a stepper motor (4) of the vehicle headlight (1) for adjusting the headlight range (LW), - the headlight control unit (3) the stepper motor (4) for calibrating the headlight range (LW) in a reference run within a reference runtime t RefLauf from an upper maximum position X MaxPosOben to a lower minimum position X MinPosUnten adjusted - the headlight control unit (3) the stepper motor (4) after reaching the lower minimum position X MinPosUnten within a predefined time t PosSicher into a safety position X MinPosSicher and via these into a target position X SollPos adjusted - the headlight control unit (3) in the event that the reference run is performed at a position between the upper maximum position X MaxPosOben and lower minimum position X MinPosUntenCurrent position X IstPosVorRef starts and the reference run terminates at a time t Abbruch is aborted, checks when the aborting took place and a) in the case that t Abbruch < t RefLauf the headlight control unit (3) always moves the stepper motor (4) by a delta distance X MinPosSicher - X MinPosunten moves upwards b) in the case that t PosSich > t Abbruch > t RefLauf the headlight control unit (3) the stepper motor (4) to at least the fuse position X MinPosSicher moves upwards c) in the case that t PosSicher ≤ t Abbruch the headlight control unit (3) does not adjust the stepper motor (4). [2] Motor vehicle (2) with a vehicle headlight (1) with a headlight range (LW) adjustable by means of a stepper motor (4) and with a headlight control unit (3) designed to carry out the method according to claim 1. [3] Motor vehicle (2) according to claim 2, characterized by , that the vehicle headlight (1) is a front headlight. [4] Motor vehicle (2) according to claim 2 or 3, characterized by , that the motor vehicle (2) has a trailer hitch.

Images