FR3083180A1 - METHOD FOR CONTROLLING A PROJECTOR AIR EXTRACTOR FOR A MOTOR VEHICLE. - Google Patents

Abstract

The invention relates to a method for controlling an air extractor of a vehicle headlamp; said air extractor comprising an air inlet and an air outlet, a ventilation chamber arranged between the latter, comprising at least one fan arranged to produce an air flow from the air inlet to the outlet air to cool at least one optical module of said projector, characterized in that the method comprises the following steps: - detecting (501) the ignition state of at least one optical module of the projector; and - putting into operation (502) of at least one fan of the air extractor when the ignition of said at least one optical module is detected. The invention also relates to a projector and a motor vehicle capable of implementing said method, as well as a computer program product and a support comprising such a program comprising instructions for implementing said method.

Description

Method for controlling a headlight air extractor for a motor vehicle.

The invention relates to a method for controlling an air extractor of a headlight of a vehicle. The invention also relates to a vehicle headlamp capable of implementing such a method. The invention also relates to a vehicle comprising such a headlamp. Finally, the invention relates to a computer program product and a data recording medium for the implementation of such a method.

To increase the efficiency of headlamps or light modules in headlamps, and in particular motor vehicle headlamps, components of the spatial modulator type can be used to form segmented beams which can be activated independently.

For example, the use of light source matrices is known. However, these dies heat up a lot due to their number and their rise in temperature rapidly degrades their performance.

The use of components such as LCD screens or micro-mirror arrays is also known. These components have operating temperature limits around 85 ° C, approximately 55 ° C below the operating temperatures of light emitting diode (LED) light sources.

Thus, it is now interesting to integrate MEMS type components (for "electromechanical microsystems"), LCD screens or lasers into a projector.

However, the limit temperature for using such components is quite low (around 85 ° C), so it is impossible to use them under normal temperature conditions for projectors. Indeed, a projector is in the form of a closed assembly comprising heating elements and positioned close to an engine, and the temperature inside the projector can reach high values. The temperature limit for using the above components is quickly exceeded.

To meet these constraints, there are projectors comprising heat exchangers coupled to fans positioned near the sensitive components to cool them directly.

A first drawback is that this type of projector does not reduce the temperature of the projector sufficiently, and the effectiveness of such a system is limited.

A second drawback of such projectors lies in the number of additional manufacturing steps and the addition of a large number of additional components to small areas during manufacturing.

A third drawback is that the replacement of such a system, in the event of a fan failure, is complicated to perform. It is thus preferable to replace the entire projector or the housing comprising the semiconductor components, which involves additional costs.

A general object of the invention is to provide a headlamp solution improving existing solutions, and allowing the use of heating components without the risk of exceeding their limit temperature of use while optimizing the life of such a solution. .

More specifically, an object of the invention is to find a solution for cooling a projector, from a reliable device and of optimal lifetime, while being effective enough to avoid the rise in temperature of the components of the projector. above their limit use temperature.

In this regard, the first object of the invention is a method for controlling an air extractor from a headlight of a vehicle; said air extractor comprising an air inlet and an air outlet, a ventilation chamber disposed between said air inlet and said air outlet, said ventilation chamber comprising at least one fan arranged to produce a flow of air from the air inlet to the air outlet to cool at least one optical module of said projector, remarkable in that the method comprises the following steps:

- detecting the ignition state of at least one optical module of the projector; and

- the operation of at least one fan of the air extractor when the ignition of said at least one optical module is detected.

According to other characteristics of the process, taken alone or in combination:

- The step of putting the at least one fan of the air extractor into operation is executed after a waiting time of a predefined duration after the detection of the ignition of said at least one optical module.

- the predefined duration is between 30 seconds to 45 minutes inclusive, or even is between 8 and 15 minutes.

the projector comprises a plurality of optical modules and in which the predefined duration of the waiting time between the detection of the ignition of at least one optical module and the operation of the fan is a function of the type, in particular of the power , the optical module whose ignition has been detected and / or the number of optical modules whose ignition has been detected.

- The method comprises a step of measuring or estimating a temperature, and in which the step of putting the fan into operation is triggered only if the measured or estimated temperature is greater than a predefined threshold temperature.

the step of measuring or estimating a temperature comprises measuring or estimating the temperature outside the vehicle, and / or comprising measuring or estimating the temperature inside the headlight and / or comprises measuring or estimating the temperature near at least one optical module of said projector.

the method comprises a preliminary calibration step to predefine a threshold temperature from a measured or estimated temperature so that this threshold temperature corresponds to a threshold temperature of a component of the projector, above which its operation risks d 'be degraded.

- The method comprises a step of measuring the speed of the vehicle and in which the operation of the fan is triggered only if the measured speed of the vehicle is less than a predefined threshold value.

- The method comprises a step of determining a fan speed, which is variable, depending on the measured or estimated temperature and / or depending on the state or not of the optical module (s).

- each optical module is associated with a predefined power and characterized in that the speed of the fan is determined as a function of the sum of the powers of the optical modules whose ignition has been detected.

- The method comprises a step of regulating the speed of the at least one fan of said projector.

- the air extractor comprises a sealing system for external particles comprising at least one sealing means, designed to take:

- an open position allowing fluid communication between the air inlet and the air outlet; and

- a closed position to prevent at least the passage of external particles;

and characterized in that the step of putting the at least one fan of the air extractor into operation comprises a step of positioning the shutter means in the open position, with optionally a delay according to a predefined duration relative to the 'instant of operation of at least one fan of the air extractor.

- The method includes a step of stopping the fan when the at least one optical module to be cooled goes from the on state to the off state.

The invention also relates to a motor vehicle headlamp, remarkable in that it comprises an air extractor comprising an air inlet and an air outlet, a ventilation chamber arranged between said air inlet and said air outlet, said ventilation chamber comprising at least one fan arranged to produce an air flow from the air inlet to the air outlet, in that said projector also comprising at least one optical module with cool, and in that the projector comprises a control device which implements the method according to one of the preceding characteristics.

The invention also relates to a vehicle, in particular a motor vehicle, remarkable in that it comprises a headlight as defined above.

Another object of the invention is also a computer program product remarkable in that it comprises program code instructions recorded on a computer-readable medium for implementing the method described above when said program is running on a computer or computer program product downloadable from a communication network and / or recorded on a data medium readable by a computer and / or executable by a computer, remarkable in that it includes instructions which, when the program is executed by a computer, lead it to implement the process described above

A final object of the invention is finally a data recording medium, readable by a computer, on which a computer program is recorded comprising instructions of program code for implementing the method described above or recording medium computer-readable comprising instructions which, when executed by a computer, lead the latter to implement the method described above.

These objects, characteristics and advantages of the present invention will be explained in detail in the following description of particular embodiments made without implied limitation in relation to the attached figures among which:

- Figure 1 is a diagram of the front of a vehicle comprising a headlight comprising an air extractor capable of implementing the method according to an embodiment of the invention;

- Figure 2A shows an air extractor comprising a sealing system comprising a hatch, according to an embodiment of the invention;

- Figure 2B shows the air extractor according to the embodiment of the invention illustrated in Figure 2A in which the hatch is in the closed position;

- Figure 2C shows the air extractor according to the embodiment of the invention illustrated in Figure 2A in which the hatch is in the open position;

- Figure 2D shows the air extractor according to a variant of the embodiment of the invention illustrated in Figure 2A in which the hatch is arranged at the entrance to the ventilation chamber;

- Figure 3A shows an air extractor according to another variant of the embodiment of the invention in which the sealing system comprises at least one flap and in which the flap is in the closed position;

- Figure 3B shows the air extractor according to the embodiment of the invention illustrated in Figure 3A in which the flap is in the open position;

- Figure 4 shows an air extractor according to another variant of the embodiment of the invention in which the sealing system is a channel extending from the outlet of the ventilation chamber;

- Figure 5 is a flowchart showing a control method according to an embodiment of the invention;

- Figure 6 shows curves for determining a ventilation flow used in a variant of the control method according to an embodiment of the invention.

In the following description, the following terms are defined and can be understood as follows:

We define by the longitudinal direction the direction oriented from front to rear relative to a motor vehicle, the adjectives front and rear being defined relative to the usual movement of the vehicle. We define by transverse direction the direction perpendicular to the longitudinal direction and oriented from right to left of a motor vehicle. The two longitudinal and transverse directions define a horizontal plane. The vertical direction is perpendicular to the horizontal plane, oriented upwards. These same directions will be used for the description of a headlamp, by considering the headlamp as it would be positioned within a vehicle.

The adjectives “upper” and “lower” will thus be used relative to the vertical direction defined above.

The expression “external particles” designates an element present in the external environment of the projector and liable to reduce the performance of the components present in the projector by contact or to damage the projector. The external particles can include, without limitation, dust, water, oil splashes, detergent splashes or sheets.

The concept of the invention is based on the use of an air extractor, arranged at the level of a projector, making it possible to evacuate the hot air present in the projector to replace it with fresh air, to reduce the average air temperature inside a projector and therefore the temperature of the components positioned inside the projector. This principle is illustrated schematically in Figure 1, which shows a headlight 103 mounted on a motor vehicle 101 equipped with an air extractor 102 according to an embodiment of the invention. Advantageously, the fixing of such an air extractor 102 on the projector 103 is removable, to allow its replacement in the event of failure.

The projector 103 comprises at least one optical module 105. This optical module comprises one or more temperature-sensitive components, comprising for example at least one semiconductor component, a MEMS, an array of micro-mirrors (DMD), a crystal screen liquid or laser. Advantageously, this optical module comprises a proper cooling system for the electronic component (s): however, since the optical module is integrated in a projector comprising an air extractor according to an embodiment of the invention, which limits the average temperature of air inside the projector, this clean cooling system can be simple and include only conduction and natural convection cooling. Thus, the optical module does not include a fan. It is thus simplified compared to the usual optical modules comprising the same electronic components. Naturally, the invention remains compatible with these traditional optical modules comprising their own cooling system with fan (s).

By "natural convection" is meant a convection which is not forced, that is to say carried out without a fan or any other similar means making it possible to impose an air flow locally in contact with or near the optical module. .

The headlight 103 comprises a lens 106, arranged flush or projecting with respect to the body 107 of the vehicle 101.

The air extractor 102 is arranged on or through a wall of the projector 103. The air extractor can thus achieve fluid communication between the interior and the exterior of the projector 103. The air extractor 102 is arranged to allow the extraction of air inside the projector to the outside of the projector 103. In one embodiment, the projector comprises an air inlet 104 of the projector. The warm air inside the projector is replaced by cooler air and the overall temperature of the air inside the projector decreases.

The air extractor 102 is preferably arranged on the upper part of the projector 103. In fact, the hot air being less dense than the cold air, the air inside the projector 103 is warmer in the part upper part of the projector 103 than in the lower part (with or without internal fan). The arrangement of the air extractor 102 in the upper part of the projector 103 thus advantageously makes it possible to extract the hottest air towards the outside of the projector and thus promotes the descent in temperature of the air to the inside of projector 103.

In one embodiment, the air extractor 102 comprises an air guide whose inlet is arranged on the upper part of the projector 103.

In one embodiment, an air inlet 104 of the projector is arranged on the lower part of the projector 103. The air inlet of the projector 104 can be arranged on the lower surface 108 of the projector. Preferably, the air inlet of the projector 104 is located below a horizontal plane passing through the air extractor 102.

In one embodiment, the air inlet of the projector 104 is arranged on the front part of the projector 104, that is to say the part closest to the lens 106 of the projector 103. Such an arrangement of the air inlet of the headlight 104 advantageously allows a cooler air inlet inside the headlight 103, in particular by moving the air inlet of the headlight 104 away from the engine of the vehicle 101, generally located at the rear of the headlight projector 103.

In one embodiment, the air inlet of the projector 104 comprises an air guide, the inlet of which is arranged on the front part and / or on the lower part of the projector 103.

The air inlet of the projector 104 may include an air filter. The air filter advantageously allows the passage of air from the outside to the inside of the projector 103 by preventing external particles from entering the interior of the projector 103 by the air inlet of the projector 104.

An example of an air extractor 201 according to a first embodiment is described below with reference to FIGS. 2A, 2B and 2C.

The air extractor 201 comprises an air inlet 203 and an air outlet 214, more particularly shown in FIG. 2C. The air extractor

201 also comprises a ventilation chamber 210. Said ventilation chamber 210 is advantageously disposed between said air inlet 203 and said air outlet 214 of the air extractor 201. The ventilation chamber 210 comprises a fan 202. By fan is meant any means for generating an air flow between the air inlet 203 and the air outlet 214.

The fan 202 can be a radial fan, an axial fan or any other type of fan. In one embodiment, the fan

202 is designed to generate a flow of air at the outlet of air whose speed is substantially equal to 5 meters per second. In one embodiment, the fan 202 is designed to generate an air flow at the air outlet of between 100 and 500 L / min.

As illustrated in FIG. 2B, the air extractor 201 is arranged in the rear and upper part of a projector 213, in a similar manner to the diagram in FIG. 1. The air inlet 203 is arranged to be positioned at inside the projector 213. The air outlet 214 is arranged to be outside the projector 213. The fan 202 thus makes it possible to draw the internal hot air inside the projector 213 through the inlet air 203 and expel it to the outside of the projector 213 and the air outlet 214 of the air extractor.

The air extractor 201 may also include a sealing system for external particles. In a non-limiting embodiment, the sealing system is also airtight. The exterior particle sealing system prevents exterior particles present in the air outside the projector 213 from entering the interior of the projector 213 when the fan is off or when the fan is not activated. .

In fact, when the air extractor 201 is operating, a through air flow is generated from the air inlet 203 to the air outlet 214 from the air extractor 201. This air flow through prevents outside particles from passing through the extractor to the inside of the projector. However, when the fan 202 is turned off, no air current is generated and it is therefore important for the preservation of the components present in the projector to close the extraction system so that no dust enters the projector by the air extractor.

In one embodiment, the air extractor does not include an air filter.

A first example of a sealing system is illustrated in FIG. 2A. In this first embodiment, the sealing system comprises a sealing means 206. The sealing means 206 may be located in the ventilation chamber 210, in the air inlet 203 or in the outlet of air 214. The shutter means 206 may be a hatch covering the entire section of the air extractor.

The shutter means 206 is designed to be able to take or to be able to move between two positions: an open position (FIG. 2C) allowing fluid communication between the air inlet and the air outlet of the extractor air and a closed position (Figure 2B) to prevent at least the passage of external particles between the air outlet and the air inlet.

In one embodiment, the shutter means 206 is movable between two limit positions: the closed position and the open position.

In the closed position, the shutter means 206 can cover a section of the air extractor so as to prevent at least the external particles from passing through this section. Said section can be located in the ventilation chamber 210, in the inlet or outlet of the air extractor.

The shutter means 206 may be a hatch made of gas-impermeable material or of material permeable to air and impermeable to external particles.

The shutter means 206 can be movable between a closed position (Figure 2B) and an open position (Figure 2C) by a translational movement or by a shutter system (s).

The air extractor 201 may also include an air guide 204. The air guide 204 makes it possible to fluidly connect the air inlet 203 of the air extractor with the ventilation chamber 210.

The air extractor 201 may also include leaktight seals 208 to guarantee sealing between the extractor 201 and the projector 213 and / or between the walls of the extractor 201 and the closure means 206.

FIG. 2D illustrates a variant of the first embodiment, in which the shutter means 206 is arranged at the entrance to the ventilation chamber 210. The two embodiments can also be combined.

In this first embodiment, the projector further comprises a control device 209 for the air extractor 201, shown in FIGS. 2A and 2D. This control device may comprise an activator, arranged to control the opening and closing of the at least one closure means 206. The activator 209 may comprise a motor or an animated arm making it possible to move the closure means 206. The control device may, in addition, comprise a computer 207 and / or a computer, physically arranged within or close to the projector or positioned remotely within the vehicle. The computer 207 can be connected to the activator 209 by a means of communication, in order to control the shutter means through the activator. The computer 207 may include a data storage medium 211 readable by the computer 207. The data storage medium 211 may include a computer program comprising instructions for controlling the activator 209.

The controller is also configured to control the fan 202 of the air extractor. The controller is configured to control the operation of the fan. In one embodiment, the control device also controls the speed of the fan, and therefore the air flow through the air extractor and through the projector.

FIGS. 3A and 3B represent an air extractor 301 according to a second embodiment, respectively in the open and closed configuration.

In this embodiment, the air extractor 301 comprises at least one shutter means 306 movable in rotation. In particular, the closure means 306 can be movable in rotation around a pivot 309, oriented in the transverse direction. This shutter means 306 is designed for, in the closed position represented by FIG. 3A, simultaneously closing the inlet and the outlet of the ventilation chamber 310. In the open position represented by FIG. 3B, it simultaneously opens the entry and exit of the ventilation chamber 310. As a variant, this closure means could open and close the air inlet 303 and the outlet 314 of the air extractor 301.

The closure means 306 is of sufficient length on either side of the pivot 309 to, in the closed position, make it possible to cover the section of the inlet of the ventilation chamber 310 and the section of the outlet of the ventilation chamber 310.

The ventilation chamber 310 may include leaktight seals 308 disposed between the pivot 309 and the wall of the projector 313. The extractor 301 may also include a leaktight seal 308 between the ventilation chamber and the walls of the projector.

The sealing means 306 may comprise a surface 305 which is impermeable to external particles and permeable to gases.

The air extractor 301 further comprises an air guide 304 designed so that the air inlet of the extractor 303 is oriented upwards or towards the upper face of the projector 313. Thus, the extractor 301 can draw in warmer air 311, rather than cooler air 312 located in the bottom of the projector.

In a third embodiment illustrated by FIG. 4, an air extractor 401 likewise comprises an air inlet 403, then an air guide 404 towards a ventilation chamber 410 equipped with at least one fan 402. In this embodiment, the sealing system comprises an outlet channel 405 having at least one curvature. This outlet channel 405 having at least one curvature is arranged between the ventilation chamber 410 comprising the fan 402 and the air outlet 414 of the air extractor 404. As a variant, the outlet channel 405 may comprise several curvatures . Preferably, said outlet channel 405 comprises a curvature between 150 ° and 200 °, that is to say that it guides the air extracted by the air extractor 401 along a path comprising such a significant curvature, before it leaves the extractor. Such a curve, substantially around 180 °, allows the outlet channel 405 to orient the air outlet 414 towards the rear wall of the projector 413. Thus, the air outlet 414 is not oriented towards the motor of the vehicle. This orientation makes it impossible or very difficult, when the fan is off, for the entry of external particles inside the projector by the air extractor. The outlet channel 405 thus fulfills the sealing function. Alternatively, the sealing system could be implemented by any other channel having at least one curvature, not necessarily positioned at the outlet of the air extractor.

In one embodiment, the outlet channel 405 further comprises a filter or a grid 415 near the air outlet 414. This grid makes it possible to brake or stop the external particles, which will tend to deposit on this grid. rather than traveling the route through the outlet channel 405.

The grid 415 covers the section of the outlet channel 405. Preferably, the grid completely covers the section of the outlet channel 405 at the air outlet 414. Preferably, the grid comprises a succession of flaps or wires. The spacing between each adjacent flap or between each adjacent wire is between 0.5 and 3 mm

Preferably, the outlet channel 405 further extends over a length sufficient to seal the external particles of the air extractor 401. The outlet channel 405 can extend over a length at least greater than 25 mm and / or less than 200mm.

The diameter or the width of the section of the outlet channel 405 can be between 15 and 50 mm. The dimensions of the section of the outlet channel 405 contribute to the sealing of the air extractor 401, while allowing the passage of the air flow during the operation of the fan 402.

The advantage of this solution is that it avoids the use of mechanical devices such as mobile shutter means, such as shutters. Advantageously, this solution can also do without an air filter.

The outlet channel 405 can also be designed to, once mounted on the headlight 413 and on a vehicle, have a slope so that water which would be present in the outlet channel, for example following a projection or by condensation, either evacuated by gravity through the air outlet 414 of the extractor 401. The air outlet 414, when the air extractor is mounted on a headlight on a vehicle, is advantageously arranged at a height lower than the air outlet of ventilation chamber 410.

In addition, in all the embodiments, the ventilation chamber is designed to have a slope with respect to a horizontal plane. This slope makes it possible, once the extractor is mounted on a headlight of a vehicle, to allow an outward flow of water on the walls of the ventilation chamber, without entering the headlight. As shown in FIGS. 2A to 4, the upper part of the ventilation chamber, arranged outside the projector, has a slope with a horizontal plane so as to evacuate the water. In these embodiments, water cannot stagnate in the air extractor or enter the interior of the projector.

In all of the alternative embodiments of the air extractor, described above as well as their combinations, the projector is equipped with a device for controlling the air extractor, as described previously in the embodiment represented by Figures 2A to 2D. This control device implements a control method, which will now be described in more detail, with reference to FIG. 5.

The control method 500 comprises a first step 501 of detecting the ignition state of an optical module of the projector.

It is considered that an optical module of the projector can take an on state in which it emits light and an off state. The first step therefore consists in determining whether an optical module is switched on. This determination can be made by detecting a light emitted by said optical module. In an alternative embodiment, the detection can be done by detecting a voltage of the power supply circuit of said optical module or even by interrogation of a control system of said optical module. As a variant, this information is simply transmitted by the on-board computer of the motor vehicle. In addition, a projector can include several optical modules, and this first step 501 can be implemented for each of the optical modules, making it possible to know their state on or off.

The control method 500 comprises a second step 502 of operating at least one fan of the air extractor when the ignition of said at least one optical module is detected.

During this start-up step, the rotation of the air extractor fan is started. Turning on the fan generates air flow into the projector from the projector air inlet to the air extractor air outlet. The hot air of the projector is thus replaced by cooler air via the air inlet of the projector and the temperature inside the projector decreases or is maintained at a temperature lower than the maximum temperature of use of the at least one optical module, that is to say at a temperature which guarantees that the limit operating temperature of the heating and sensitive components is not reached.

The step of putting 502 into operation of the at least one fan can advantageously comprise the following substeps:

- activation of at least one fan; then

- the displacement of a shutter of the air extractor to reach an open position.

Preferably, the step of moving the shutter is performed with a delay according to a predefined duration relative to the instant of operation of the at least one fan, for example of at least one second, preferably at least 3 or 4 seconds, very preferably between 3 and 6 seconds after the execution of the activation step. In this way, the activation of the fan causes the ventilation chamber to be pressurized before the shutter means open. This overpressure advantageously makes it possible to guarantee that no particle can enter the interior of the projector through the extractor when it is put into operation.

In one embodiment, the step of putting into operation at least one fan of the air extractor is executed as soon as the ignition of at least one optical module is detected.

In an alternative embodiment, once the ignition of at least one optical module is detected, the step of putting a fan into operation is performed after a waiting time of a predefined duration. Indeed, when the optical modules are switched on, the temperature rise takes a certain time. During this time, you can choose not to start the fan operation in order to preserve it. By operating the fan for a shorter time, it also advantageously limits the power consumption of the system.

This time lag between these two stages makes it possible to reduce the overall operating time of an air extractor and thus increase its service life.

The predefined duration of the waiting time between the detection of the ignition of at least one optical module and the start-up of the fan can be between 30 seconds and 45 minutes inclusive. Preferably, the predefined duration is between 8 and 15 minutes. These duration values between the two stages advantageously make it possible to maintain the performance of the optical module since the air extractor is started before the temperature approaches the limit temperature for using the optical module. At the same time, this duration significantly extends the life of the air extractor. We note that the duration of a night car journey is often shorter than a day journey, and often less than thirty minutes. Triggering the operation of the air extractor after ten minutes statistically extends the life of said air extractor between 30 and 50%.

When the projector comprises a plurality of optical modules, this predefined duration of the waiting time may be a function of the optical module or modules whose ignition has been detected. This waiting time will be all the shorter as the power (and therefore its heating effect) of the optical module is high.

In one embodiment, a predefined duration of the waiting time is associated with each optical module and / or with each combination of optical modules. The waiting time between detection and start-up is then the time associated with the optical module or the combination of optical modules whose ignition has been detected.

Alternatively, the waiting time can be a function of the sum of the powers of each optical module whose ignition has been detected.

According to another alternative embodiment, the method can take into account at least one temperature value, by at least one measurement and / or an estimation of this temperature value. Thus, in this variant embodiment, the method comprises an intermediate step of measuring or estimating 503 of a temperature. The fan is then put into operation if the measured or estimated temperature is higher than a predefined threshold temperature.

The measured temperature can be a temperature measured outside the vehicle, for example the ambient temperature. For example, it may be predetermined that the air extractor is not necessary under an ambient temperature less than or equal to a certain threshold value, for example 15 degrees Celsius.

Alternatively, the method can take into account a temperature measured inside the projector and / or a temperature measured near at least one optical module of said projector. In particular, several electronic components or electronic cards already have a temperature measurement, useful for other functionalities. The method can receive this or these values available for the implementation of the control method of the invention.

According to a variant, the method takes into account an estimated temperature, which can be a function of a measured temperature or from a temperature estimation model.

The temperature threshold value is naturally linked to the limit temperature for using one (or more) components of an optical module. The predefined threshold temperature may have been predefined by a calibration step allowing the measured or estimated temperature to be linked to the actual temperature of a temperature-sensitive component. This calibration step therefore advantageously makes it possible to determine from which measured or estimated temperature value the component of the optical module actually reaches its operating limit temperature.

This approach makes it possible to avoid starting the fan of the air extractor if the temperature of the sensitive component (s) is sufficiently low, in particular if the temperature of the component is sufficiently low so as not to risk its degradation or its malfunction.

The step of measuring or estimating a temperature 503 can be executed before and / or after the waiting time between the step of detecting the ignition state of an optical module and putting it into operation of the fan, or even before step 501 of detecting the ignition state of an optical module of the projector. Naturally, this step can include measuring or estimating several temperature values, spread over time according to a chosen frequency, and / or distributed in the space around and / or in the projector. In this case, a threshold value can be reliably deduced from this plurality of available values.

In one embodiment, the control method comprises a step of measuring the speed 504, or of taking into account the speed of the vehicle comprising the headlight comprising the air extractor. This step of taking into account the speed 504 can be executed before and / or after the waiting time between the step of detecting the ignition state of an optical module and the operation of the fan. This step 504 can be used to replace or supplement the step of measuring or estimating a temperature 503.

In this embodiment, the operation of the fan is triggered if the measured speed of the vehicle over a predetermined duration is less than a predefined speed threshold value. The measured speed taken into account can be a function of a maximum speed or an average speed over a predetermined period.

This approach takes into account the fact that below a certain speed of the vehicle, the temperatures of the engine environment are higher than at higher speeds. Speed can therefore affect the temperature inside a projector, which is usually located a short distance from the engine. This speed threshold value is for example preset by calibration, such a calibration making it possible to establish a relationship between the speed of the vehicle, the temperature of the engine, and the temperature of a headlight.

Thus, by suspending the operation of the air extractor fan before the temperature of the optical components increases, the life of the fan and the air extractor is advantageously increased without reducing the performance of the at least one optical module and one projector.

In one embodiment of the invention, the method implements a determination of the optimal fan speed, which is variable.

In this embodiment, the method comprises a step of determining the speed of the fan 505, 507, and optionally a step of regulating 506 of this speed.

The method may include a first step 505 of determining the speed of the at least one fan of said projector as a function of the temperature calculated or estimated within the projector. The fan rotation speed will be higher as this temperature approaches the threshold value and / or increases on a steep slope.

The control method can also include a second step 507 of determining a fan speed as a function of the optical module or modules whose ignition has been detected. Thus, if the optical module whose ignition has been detected is of low power, the fan speed, and therefore the air flow passing through the projector will be lower than if the optical module whose ignition has been detected is of stronger power.

In one embodiment, a fan speed is associated with each optical module and / or with each combination of optical modules. The fan speed when it is put into operation is then the speed associated with the optical module or the combination of optical modules whose ignition has been detected.

In an alternative embodiment, each optical module is associated with a predefined power and the method comprises a step of determining a fan speed as a function of the sum of the powers of the optical modules whose ignition has been detected.

In one embodiment, the method comprises only one of the first determination step 505 and of the second determination step 507.

In an alternative embodiment, the determination step comprises the implementation of a combination of the first determination step 505 and the second determination step 507. FIG. 6 thus illustrates by way of example a step of determination of the operating speed of the air extractor fan (which includes only one in this example) as a function of both a measured temperature and the optical modules switched on. For this, three curves C1, C2, C3 are pre-established, for example in a preliminary calibration step, to determine the recommended ventilation speed as a function of an equivalent temperature of the projector. The first curve C1 corresponds to a situation in which only one low beam optical module is in the on state. The second curve C2 corresponds to a situation in which an optical low beam module and a high beam optical module are both in the on state. The third curve C3 corresponds to a situation in which a low beam optical module, a high beam optical module and at least one other optical module are in the on state. Each of these curves makes it possible to determine (on the ordinate) the ventilation rate (in l / min), that is to say indirectly the fan speed, recommended for cooling the projector as a function of the equivalent temperature of the projector (in abscissa). As a reminder, the operating state, lit or not, of each optical module was determined during the first step 501 of detecting the ignition state. The equivalent temperature is a value representative of the temperature inside the projector, calculated from values measured by several sensors.

For example, before turning on the headlight functions, the equivalent headlight temperature can be a ratio between the temperature of the engine environment and the outside temperature of the vehicle.

In all cases, this temperature value can be arbitrary, since the calibration step or a calculation model makes it possible to deduce the real temperature of a sensitive component from knowledge of this arbitrary temperature value, in particular the temperature equivalent.

Optionally, the method comprises a step 506 for regulating the speed of the fan in order to reach a predetermined temperature set point within the projector. This temperature setpoint is advantageously set below the threshold value, with a safety margin. Naturally, this regulation step is only implemented in a situation where the temperature would exceed this setpoint without regulation. In this case, the fan speed is regulated according to a set temperature to be reached. In this regulation, the initial speed of the fan is determined by the determination step (s) 505, 507. This speed can then in practice substantially oscillate around the speed determined by FIG. 6.

The method may finally comprise a step 508 of stopping the fan of the air extractor. The fan can be stopped when the at least one optical module to be cooled goes from the on state to the off state.

Similarly to putting into operation, the method comprises a step of stopping the extractor comprising a step 508 of stopping the fan and optionally a step of moving the shutter means in the closed position.

Preferably, the stop step 508 of the fan is executed with a delay on the opening of the shutter means, at least one second, preferably at least 3 or 4 seconds, very preferably between 3 and 6 seconds after execution of the step of moving the shutter means. In this way, it can be guaranteed that no dust can enter the interior of the projector through the extractor when it is stopped.

The steps of the method described above can be independent or be combined with each other, making it possible to obtain several embodiments of the control method. In addition, they are repeated periodically, to take account of any change in situation, such as switching an optical module on or off, a change in temperature, vehicle speed, etc.

The invention also relates to a motor vehicle headlamp comprising hardware and / or software elements implementing the method according to the invention, in particular hardware and / or software elements designed to implement the method according to the invention.

The projector comprises at least one air extractor comprising an air inlet and an air outlet, a ventilation chamber arranged between said air inlet and said air outlet, said ventilation chamber comprising at least one fan arranged to produce an air flow from the air inlet to the air outlet. The projector also includes at least one optical module to be cooled and a control device which implements the control method as described above.

The invention also relates to a vehicle comprising such a headlamp and implementing the method described in the present application.

The invention also consists of a computer program product comprising program code instructions recorded on a computer-readable medium for implementing the method according to the invention when said program is running on a computer.

The invention also consists of a computer program product downloadable from a communication network and / or recorded on a data medium readable by a computer and / or executable by a computer, comprising instructions which, when the program is executed by a computer, lead the latter to implement the method according to the invention.

The invention also consists of a data storage medium, readable by a computer, on which is recorded a computer program comprising program code instructions for implementing the method according to the invention.

The invention also consists of a computer-readable recording medium comprising instructions which, when executed by a computer, lead the latter to implement the method according to the invention.

The device for controlling the air extractor is advantageously connected to a computer or to a computer comprising such a computer program. As a variant, such a computer is integrated into the control device.

Claims (16)

Claims: 1. Method for controlling an air extractor from a headlight of a vehicle; said air extractor comprising an air inlet and an air outlet, a ventilation chamber disposed between said air inlet and said air outlet, said ventilation chamber comprising at least one fan arranged to produce a flow of air from the air inlet to the air outlet to cool at least one optical module of said projector, characterized in that the method comprises the following steps: - Detection (501) of the ignition state of at least one optical module of the projector; and - putting into operation (502) of at least one fan of the air extractor when the ignition of said at least one optical module is detected, characterized in that it comprises a measurement or estimation step (503 ) of a temperature, and in which the step of putting the fan into operation (502) is triggered only if the measured or estimated temperature is greater than a predefined threshold temperature. 2. Control method according to claim 1, characterized in that the step of putting into operation (502) of at least one fan of the air extractor is executed after a waiting time of a predefined duration after detecting (501) the ignition of said at least one optical module. 3. Control method according to claim 2, wherein the predefined duration is between 30 seconds to 45 minutes inclusive, or even is between 8 and 15 minutes. 4. The control method as claimed in claim 2 or 3, in which the projector comprises a plurality of optical modules and in which the predefined duration of the waiting time between the detection (501) of the ignition of at least one optical module and the operation (502) of the fan is a function of the type, in particular of the power, of the optical module whose ignition has been detected and / or of the number of optical modules whose ignition has been detected. 5. Control method according to the preceding claim, characterized in that the step of measuring or estimating (503) a temperature comprises measuring or estimating the temperature outside the vehicle, and / or comprises measuring or estimating the temperature inside the projector and / or comprises measuring or estimating the temperature near at least one optical module of said projector. 6. Control method according to claim 4 or 5, characterized in that it comprises a preliminary calibration step to predefine a threshold temperature from a measured or estimated temperature so that this threshold temperature corresponds to a threshold temperature d a component of the projector, above which its operation may be degraded. 7. Control method according to one of the preceding claims, characterized in that it comprises a step of measuring the speed of the vehicle (504), and in which the operation (502) of the fan is triggered only if the measured vehicle speed is less than a predefined threshold value. 8. Control method according to one of claims 4 to 7, characterized in that it comprises a step of determining (505) a speed of the fan, which is variable, as a function of the measured or estimated temperature and / or according to the on or not on state of the optical module (s). 9. Control method according to the preceding claim, wherein each optical module is associated with a predefined power and characterized in that the fan speed is determined as a function of the sum of the powers of the optical modules whose ignition has been detected. 10. Control method according to one of claims 8 or 9, characterized in that it comprises a step of regulating (506) the speed of the at least one fan of said projector. 11. Control method according to one of the preceding claims, in which the air extractor comprises a sealing system for external particles comprising at least one sealing means (206; 306), designed to take: - an open position allowing fluid communication between the air inlet and the air outlet; and - a closed position to prevent at least the passage of external particles; and characterized in that the step of operating (502) the at least one fan of the air extractor comprises a step of positioning the shutter means (206; 306) in the open position, optionally with a delay according to a predefined duration relative to the instant of operation of at least one fan of the air extractor. 12. Control method according to one of the preceding claims, characterized in that it comprises a step of stopping (508) the fan when the at least one optical module to be cooled goes from the on state to the off state. . 13. Headlamp (213; 313; 413) of a motor vehicle, characterized in that it comprises an air extractor (201; 301; 401) comprising an air inlet (203; 303; 403) and an outlet d air (214; 314; 414), a ventilation chamber (210; 310; 410) disposed between said air inlet (203; 303; 403) and said air outlet (214; 314; 414), said ventilation chamber comprising at least one fan (202; 302; 402) arranged to produce an air flow from the air inlet to the air outlet, in that said projector also comprising at least one optical module ( 105) to be cooled, and in that the projector comprises a control device which implements the method according to one of the preceding claims. 14. Vehicle, in particular motor vehicle, characterized in that it comprises a headlight according to the preceding claim. 15. A computer program product characterized in that it comprises program code instructions recorded on a computer-readable medium for implementing the method according to any one of claims 1 to 12 when said program is running on a computer. or product computer program downloadable from a communication network and / or recorded on a data medium readable by a computer and / or executable by a computer, characterized in that it comprises instructions which, when the program is executed by a computer, lead the latter to implement the method according to any one of claims 1 to 13. 16. data recording medium (211), readable by a computer (207), on which is recorded a computer program comprising program code instructions for implementing the method according to one of claims 1 to 12 or computer-readable recording medium comprising instructions which, when executed by a computer, cause the latter to implement the method according to any one of claims 1 to 12.