JPS6337733B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a device for dynamically adjusting the position of a headlamp of a vehicle, in particular a motor vehicle, according to the relative position of the body of this vehicle with respect to its turning device.

Devices for correcting the position of vehicle headlights are conventionally constructed. Some of these devices are static and others are dynamic.

Static compensators adjust the load and the load distribution between the front and rear axles with a relatively long response time. Such a device acts to correct the headlight position when the vehicle is moving.

Dynamic adjustment devices have also been created which ensure proper positioning of the headlights under all driving conditions of the vehicle. Some of these devices include a compensator (eg, a pendulum) coupled to the headlight and actuated via gravity. Such a device can appropriately adjust the headlights when the vehicle is traveling on a sloped road.

Other dynamic adjustment devices include sensors that detect the relative position of the vehicle body during longitudinal or fore-aft tilting with respect to the rotating part. These sensors act via correction filters on a drive device which is adapted to correct the headlight position in accordance with the signals sent by the sensors. Some of these devices are hydraulic;
In this case, the filtering of undesired high-frequency signals (in particular those caused by the vehicle driving over the pavement) takes place at the level of the duct of the hydraulic system. If the regulating device is electrical, the filtering is performed by an electrical low-pass filter.

There are multiple types of driving conditions that require correction of the damage prevention phenomenon and headlight position based on road conditions.

Thus, paving stones provide relatively high frequency protection of 5 to 15 Hz.

Potholes and open drainage ditches produce pitching vibrations of 5 to 10 Hz. However, these protections are relatively rare and therefore do not significantly impair piloting comfort.

There are vibrations caused by rapid acceleration and braking on the order of 1 to 2 Hz.

Vehicle vibrations above 15Hz are not bothered by the persistence of the eye retina, which automatically integrates these rapid modifications of headlight position. Additionally about 2 to 15Hz
The lower frequencies in between are filtered to some extent by the vehicle suspension and are therefore attenuated when these frequencies reach the headlight level. Even if they are attenuated, these frequencies still cause trouble.

Conventional adjustment devices of this type introduce a phase shift between the time of vehicle tilt and the reaction time of the corrector for phenomena with a frequency equal to or higher than the cutting frequency of the filtering device. There are serious obstacles. For example, if this shear frequency is 2 Hz, more rapid phenomena such as those caused by pavement will be damped by filtering, but will still reach the headlamp drive and cause some body damage due to phase shifts. accompanied by physical discomfort.
That is, when the vehicle travels on the pavement, the correction intervenes in exactly the opposite phase to the pitching vibrations of the vehicle. In this case, the headlights, for example, are directed upwards when the front part of the vehicle body also moves upwards.

Another drawback of existing adjusting devices is that the compensating piece is permanently stressed in response to rapid events and therefore has a relatively short operating life.

The object of the invention is to provide a dynamic headlamp adjustment device for a vehicle which ensures comfortable night driving in all driving conditions and for all road conditions without the above-mentioned obstacles. .

It is therefore an object of the invention to provide at least one sensor, each coupled to each headlamp of said vehicle, adapted to supply a signal representative of the relative position of a wheel with respect to the bodywork of said vehicle, said sensor being connected to each headlamp of said vehicle, said and a drive device controlled by a control device guided by the position signal through a low-pass filter adapted to eliminate unwanted frequencies, the drive device controlling the position of the headlight of the vehicle according to the relative position of the wheels with respect to the vehicle body. The dynamic adjustment device is characterized in that the filter is provided with a device that gives the filter a variable frequency cutting characteristic according to the amplitude of a signal applied to the filter by one (or a plurality of) sensors. That's what we're trying to offer.

These features make it possible for the adjusting device according to the invention to reduce the difference between phenomena requiring correction and phenomena for which correction is not desirable due to the unavoidable phase shift between the prevention phenomenon and the corrective action applied to the headlights. can be identified.

According to a first embodiment, an apparatus for imparting a variable shear frequency characteristic to a filter includes components that define an amplitude threshold at which the filter has a predetermined shear frequency. In this way, the filter characteristics are precisely adapted to different protection phenomena requiring adjustment of the position of the headlight.

According to an advantageous embodiment, the filter cutoff frequency is 2 Hz for amplitudes above the threshold;
This cutoff frequency is 0.3Hz for amplitudes below this threshold.

This means that high-frequency signals between 2 and 15 Hz and with low amplitudes, such as those resulting from driving on pavement, are not taken into account and therefore do not interfere with the driving comfort.

According to a preferred embodiment of the invention, the filter is of electrical type and is formed by a resistor R in series and a capacitor C in parallel with an L-shaped RC network. The resistor is connected in parallel in an anti-parallel circuit to two rectifiers whose amplitude threshold in the pass direction is determined by an internal resistance.

According to another characteristic, the rectifier is a diode.
Advantageously, these diodes are connected in series with a resistor which adjusts the cutoff threshold.

The embodiment described above has the advantage of being easily adapted to a static adjustment device for the position of the headlights of a vehicle by using two simple diodes and two inexpensive resistors.

However, it may be recognized that the absolute value of the above-mentioned threshold must be sufficiently high to effectively eliminate low-amplitude flickering, which occurs, for example, when a vehicle drives on pavement, especially at moderate speeds. . This means that in some cases the average amplitude movements resulting from acceleration or deceleration of the vehicle are no longer taken into account and are not intervened in adjusting the headlight position in this case. This deficiency in accommodation for such movements becomes even more inconvenient as response and accuracy become important.

Thus, the present invention also provides a second embodiment that effectively suppresses device response in the case of low amplitude movements, such as those associated with repeated driving on pavement or over open drainage ditches, but at least as effective as driving and road safety. dynamic adjustment devices that adjust the vehicle headlight position according to the relative position of the wheels with respect to the vehicle body, ensuring effective dynamic adjustment for other low or medium amplitude movements when useful for This is what we provide.

It is therefore an object of the present invention to provide a dynamic adjustment device of the type described above, in which two amplitude thresholds are determined by means of components, each cooperating with the movement of the vehicle body relative to the wheels, and for each one of which the filter has a predetermined cutting frequency. , the absolute values of the two thresholds are different from each other,
It is an object of the second embodiment to provide a dynamic adjustment device in which the absolute value of the threshold value associated with the movement caused by each acceleration is lower than the absolute value of the threshold value associated with the movement caused by deceleration.

The threshold value for the acceleration-related signal is determined to be low enough to respond to low accelerations. However, these low accelerations are inconvenient for drivers who would otherwise cross vehicles with rising light beams. Also, the threshold values for signals related to braking or deceleration have higher amplitudes. As a result of experiments, the inventor found that these two
When the values of the two thresholds are adjusted in this way, undesirable responses that cause flickering, for example when passing over pavement, completely disappear and even with light accelerations, which significantly increases safety on the road. It has been found that effective adjustment of the headlights can be introduced to the resulting movements.

The inventor has also found through experimentation that in the case of low decelerations, this adjustment device does not result in a correction of the headlight position. Moreover, this is not an inconvenience since in this case the headlight beam is lowered so as not to cause any problems with regard to road safety.

According to an advantageous construction of this second embodiment, the filter cutoff frequency is determined by the amplitude of the signal above the threshold associated with acceleration or the signal amplitude above the other threshold associated with deceleration (with the opposite sign). ), and the cutting frequency is 0.15 Hz when the signal does not exceed the respective threshold depending on its sign. This means that high-frequency signals with low amplitudes between 0.15 and 1 to 2 Hz and resulting from driving on the pavement are not taken into account. Also, acceleration signals with a frequency of the order of 1 Hz and an amplitude not much larger than the amplitude of the signal resulting from driving on the pavement are taken into account and an adjustment device for correcting the headlight position is interposed. The filter is electrical and consists of an L-shaped RC network, advantageously formed by a resistor R in series and a capacitor C in parallel. The resistor is connected in parallel to anti-parallel circuits of two sets of rectifiers having internal threshold values different from each other in the passing direction, and fixes each of the threshold values. This difference between these internal thresholds is obtained by arranging one of the rectifiers, ie the one that passes an electrical signal related to the relative position corresponding to braking or deceleration. The number of unit rectifiers is greater than the number of other rectifier devices. However, as a variant it is also possible to use unit rectifiers, for example diodes with different internal thresholds. The rectifier of each rectifying device is preferably connected in series with a resistor for adjusting the cutoff threshold.

Embodiments of the dynamic adjustment device of the present invention will now be described in detail with reference to the accompanying drawings.

According to the embodiment shown in FIG.
The vehicle is equipped with a first sensor 1 located between the front axle and the vehicle body to detect relative movement therebetween. A similar sensor 2 is connected to the rear axle.

The signals generated by each sensor 1, 2 are sent to a mixer 3
Process with. The mixer 3 generates a signal indicating the tilting or pitching of the vehicle while the vehicle is running. The output of the mixer 3 is sent to a low pass filter 4 formed in this example by an L-shaped RC resistor capacitor circuit 5.

The output of the filter 4 is sent to a control and amplification device 6 which supplies a power signal to a drive device 7 which causes the movement of the vehicle headlamp 8.

Filter 4 consists of a resistor 9 and a capacitor 1 in series.
It is equipped with 0. The resistor 9 is connected in parallel to a device consisting of anti-parallel diodes 11,12.
Each diode 11, 12 has a regulating resistor 13, 14
are connected in series.

The amplitude of the input signal of filter 4 is
When thresholds S ₁ and S ₂ of 1 and 12 are exceeded, each diode 11 and 12 reduces the value of the series resistance of the RC circuit through the corresponding half cycle of the signal. time constant RC
It also decreases and the cutoff frequency increases. In this way, the filter shifts its shear frequency according to the amplitude of the signal applied to it.

In the illustrated case using common industrial diodes, the internal resistance of these diodes is not sufficient to obtain a cut-off frequency of 2 Hz. This is because each resistor 13, 14 is provided in series with each of these diodes.

The function of the regulating device according to the invention is illustrated in FIG.

f _e is the frequency of the input signal S _E of filter 4, and f _c
is the frequency of the output signal S _S. During period A, the frequency f _e of the input signal is lower than the cutoff frequency f _c of the filter 4 . The signal therefore returns entirely to the output terminal of the filter 4. In this case, it is applied to static correction, for example, when changing the load on the vehicle.

During period B, the frequency f _e exceeds the cutoff frequency of the filter. However, since the high frequency amplitude of the input signal is smaller than the threshold values S ₁ and S ₂ generated by the diodes 11 and 12, the signal passes through the filter 4 in its entirety.
On the output side, this signal is simply the average value of the input signal returned. Also, high frequency signals are removed by a filter 4. In this case, this corresponds to running on pavement.

During period C, the frequency f _e is still higher than the cutting frequency f _c . However, the amplitude of the high frequency signal exceeds the thresholds S ₁ , S ₂ provided by the diodes. High frequency signals do not cause phase shifts, but their amplitudes are below the thresholds S ₁ , S ₂
only decreases. This case corresponds to driving on a road with extremely poor conditions.

During period D, this is related to the case where a severe braking action is applied on a rough road. If the input signal exceeds the threshold S ₁ , S ₂ , this signal will be reduced by the threshold when it reaches the output terminal. If this phenomenon continues, the filter 4 obtains the same value as the input signal at its output terminal.

The cutting frequency of the filter 4 is chosen to be, for example, 2 Hz for high amplitudes, while for low amplitudes this frequency is 0.3 Hz. At this low amplitude, the signal attenuation is therefore significant and the phase shift introduced at high frequencies has no effect on the headlamp adjustment.

The adjusting device according to the invention according to the embodiment shown in FIG. 3 comprises a first sensor 101 located between the front axle and the vehicle body and adapted to detect relative movements therebetween. A similar sensor 102 is connected to the rear axle. The signals generated by each sensor 101, 102 are processed by a mixer 103. Mixer 103 generates a signal representing the heel or pitch of the vehicle while it is running. The output terminal of the mixer 103 is the low-pass filter 10
It is connected to 4. For example, the filter 104 is
It is formed by a shaped resistor-capacitor RC circuit 105. The output of filter 104 is sent to control amplifier 106 . The control amplifier 106 provides a power signal to a drive 107 that operates the vehicle's headlights 108. Filter 104 includes a series resistor 109 and a parallel capacitor 110. Resistor 1
09 is connected in parallel to a circuit consisting of two anti-parallel diode combinations. One of these combinations comprises two diodes 111 and the other combination comprises three diodes 112. Each of these combinations has a regulating resistor 113, 1, respectively.
14 in series.

The function of this adjustment device is illustrated in FIG.

f _e is the frequency of the input signal S _E of the filter 104, and f _c is the frequency of the output signal S _S. During period A, the frequency f _e of the input signal is lower than the cutoff frequency f _c of filter 104 . The signal is therefore all returned to the filter output terminal producing the correction signal, in this case applied for static correction when changing the load on the vehicle.

During period B, frequency f _e exceeds the cutoff frequency of filter 104 . However, the high frequency amplitude of the input signal is smaller than not only the absolute value of the threshold S ₁ corresponding to deceleration, but also the lower value of the threshold S ₂ produced by diode 112 for acceleration, and the signal is completely filtered. 104 and returns this signal at the filter output terminal. Also, high frequency signals are removed by a filter 104. In this case, this corresponds to running on pavement.

It is clear that during the period C, which corresponds to a light acceleration, the amplitude of the signal S _E exceeds the value of the acceleration threshold S ₂ .
This is reflected in the headlight correction which is slightly lowered as the output signal S _S changes.

During the period D, which corresponds to the optical deceleration which produces approximately the same amplitude change as the acceleration period C, no change in the signal S _S occurs because the amplitude remains below the threshold S ₁ .

In this case, exceeding the threshold value S ₁ causes a signal change in the response curve S _S only when the braking action is longer, as in the case of period E. This then produces a response in the event of severe braking.

The cutting frequency of the filter 104 is chosen to be, for example, 1 to 2 Hz for large amplitudes, while for small amplitudes this frequency is 0.15 Hz.

According to the invention, it is advantageous to use Zener diodes arranged in series instead of diodes arranged in anti-parallel.

Although the present invention has been described in detail with respect to its embodiments, it is of course possible to make various changes and modifications to the present invention without departing from its spirit.

[Brief explanation of the drawing]

FIG. 1 is a circuit diagram of a first embodiment of the headlamp position adjustment device of the present invention _, and FIG. 2 shows the function of the adjustment device shown in FIG. FIG. 4 is a diagram showing a comparison between the output signal S _S of the filter of the present adjustment device for controlling the movement of the headlamp and the output signal S S of the filter of the present adjustment device for controlling the movement of the headlamp. FIG. 3 is a circuit diagram of a second embodiment of the present adjusting device, and FIG. 4 is a diagram similar to FIG. 2 showing the function of the adjusting device of FIG. 1, 2...sensor, 4...filter, 5...resistance capacitor circuit, 6...control amplifier, 7...
Drive device, 8... Headlight, 11, 12... Diode, 13, 14... Adjustment resistor.

Claims (1)

Claims: 1. at least one sensor adapted to provide a signal indicative of the relative position of a wheel with respect to the body of a vehicle, each coupled to each headlamp of said vehicle and configured to detect undesirable signals of said position signal; a drive device controlled by a control device guided by the position signal through a low-pass filter designed to eliminate frequencies;
a dynamic adjustment device for adjusting the position of a headlamp of said vehicle according to the relative position of said wheels with respect to said vehicle body; A dynamic adjustment device characterized in that the filter is provided with a device for imparting a shearing characteristic to the filter. 2. The adjustment according to claim 1, wherein the device for imparting variable frequency shearing characteristics to the filter is constituted by a component that determines an amplitude threshold at which the filter has a predetermined shearing frequency. Device. 3. A patent characterized in that the cutoff frequency of the filter is approximately 2 Hz for signal amplitudes greater than a threshold value, but is 0.3 Hz for signal amplitudes smaller than this threshold value. An adjusting device according to claim 1 or 2. 4. The filter is electrical, has an L-shaped RC network, and consists of a series resistor and a parallel capacitor, and the resistor is connected to two antiparallel filters that determine the amplitude threshold by the internal resistance in the passing direction. 4. The adjusting device according to claim 1, wherein the adjusting device is connected in parallel to a rectifier circuit. 5 Two amplitude thresholds, each related to the motion of the vehicle body with respect to the wheels, for which the filter has a predetermined cutoff frequency are determined by each component, and the absolute values of the thresholds are different from each other. 2. The adjusting device according to claim 1, wherein the absolute value of the threshold value associated with the movement caused by acceleration is lower than the absolute value of the threshold value related to the movement caused by deceleration. . 6 The cutoff frequency of the filter is 1 to 2 Hz for signal changes that exceed thresholds related to acceleration or thresholds related to deceleration; 6. The adjusting device according to claim 5, wherein the cutting frequency is set to 0.15 Hz when there is no signal. 7. The filter is electrical, has an L-shaped RC network, and consists of a resistor R in series and a capacitor C in parallel, each resistor having a different internal threshold in the direction of passage. 7. The regulating device according to claim 5, wherein the regulating device is connected in parallel to a circuit of two antiparallel rectifier combinations for determining a threshold value. 8. The adjusting device according to claim 7, wherein the rectifier combinations are provided with different numbers of rectifiers for the two combinations. 9. The regulating device according to any one of claims 3, 4, 7 and 8, characterized in that a diode is used as a rectifier. 10. A regulating device according to any one of claims 3, 4 and 7 to 9, characterized in that each rectifier is connected in series with a regulating resistor for the cut-off threshold.