Patent Publication Number: US-10767831-B2

Title: Motor vehicle headlight air extractor

Description:
BACKGROUND OF THE INVENTION 
     Field of the Invention 
     The invention concerns an air extractor for a headlight, in particular an air extractor for a motor vehicle headlight. The invention also relates to a headlight including an air extractor and a motor vehicle including a headlight of this kind. The invention finally concerns a method of using an air extractor of this kind. 
     Description of the Related Art 
     To improve the efficiency of headlights or the lighting modules in headlights, in particular in motor vehicle headlights, components of the light spatial modulator type may be used to form segmented beams that can be activated selectively. Light source matrices are one example of components of light spatial modulator type. However, these matrices heat up considerably because of their number and the rise in temperature rapidly degrades their performance. 
     Also known as another example of light spatial modulator type components are components of LCD screen type or matrices of micromirrors (also known as digital micromirror devices or DMD). 
     It would therefore be beneficial to integrate into a headlight components of light spatial modulator type such as MEMS (microelectromechanical systems), matrices of micromirrors, LCD screens or lasers. 
     However, the limit operating temperature of components of this kind is relatively low (around 85° C.), and it is therefore impossible to use them under the usual headlight temperature conditions. In fact, a headlight takes the form of a closed assembly including heat-generating elements positioned in the vicinity of an engine, the temperature inside the headlight can reach high values and the limit operating temperature of the components is rapidly exceeded. 
     Also, components of this kind require an environment that is sealed, in particular sealed against external particles. In fact, the presence of external particles can greatly reduce the performance of the electronic components in the headlight. The headlight must therefore be protected from the external environment. 
     To address these constraints there exist headlights that include heat exchangers coupled to fans positioned in the vicinity of the sensitive components in order to cool them directly. 
     However, a first disadvantage of such headlights is the number of additional manufacturing steps and the addition of a large number of extra components in small areas during manufacture. 
     A second disadvantage is that a system of this kind is complicated to repair in the event of a fan failing. It will therefore be preferable to replace the entire headlight or the housing containing the light spatial modulator type components, which involves additional costs. 
     BRIEF SUMMARY OF THE INVENTION 
     A general object of the invention is to provide a headlight solution improving the existing solutions and enabling the use of heat generating components without risk of exceeding their limit operating temperature. 
     To be more precise, a first object of the invention is to find a compromise allowing the use of light spatial modulator type components in a headlight so that their temperature is kept below the limit operating value at the same time as guaranteeing that the headlight is sealed. 
     A second object of the invention is to provide a headlight solution that is simple to implement at lower cost. 
     According to a first aspect, the invention concerns a vehicle headlight air extractor including: an air inlet and an air outlet; a ventilation chamber disposed between said air inlet and said air outlet of the air extractor, said ventilation chamber including a fan adapted to produce a flow of air from the air inlet to the air outlet; and a sealing system against external particles. 
     In one embodiment, the sealing system against external particles includes at least one blocking means designed to assume an open position and a closed position. The open position allowing fluidic communication between the air outlet and the air inlet and the closed position enabling prevention of at least the passage of the external particles between the air outlet and the air inlet. 
     In one embodiment, the air extractor includes a control device of the at least one blocking means. 
     In one embodiment, the at least one blocking means is arranged in the air outlet and/or in the air inlet. 
     In one embodiment, the at least one blocking means is mobile between the open position and the closed position by movement in rotation about an axis or by movement in translation. 
     In one embodiment, the sealing system against external particles includes, between the ventilation chamber and the air outlet, a channel having a bend. 
     In one embodiment, said channel has a slope when the air extractor is integrated into a headlight for evacuating liquid to the air outlet. 
     In one embodiment, the air outlet includes a grille. 
     In one embodiment, the air inlet includes an air guide oriented toward upper side of the air extractor. 
     According to a second aspect, the invention concerns a vehicle headlight including an air extractor according to the first aspect of the invention. 
     In one embodiment, the headlight further includes a headlight air inlet optionally including an air filter. 
     In one embodiment, the air extractor is arranged on an upper and/or rear part of the headlight. 
     In one embodiment, the headlight air inlet is arranged on a lower and/or front part of the headlight. 
     In one embodiment, the air extractor is removably fixed to the headlight. 
     In one embodiment, the headlight further includes at least one optical module including at least one electronic component and at least one system for cooling said electronic component, said cooling system including only a system for cooling by conduction. The at least one electronic component may be a light spatial modulator. 
     According to a third aspect, the invention concerns a method of controlling a headlight air extractor according to the second aspect of the invention in which the air extractor includes a mobile blocking means. Said method includes the following steps: activating the fan, then opening the at least one blocking means. 
    
    
     
       BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS 
         FIG. 1  is a diagram of the front of a vehicle including a headlight including an air extractor according to a first embodiment of the invention. 
         FIG. 2A  represents an air extractor according to one embodiment of the invention in which the sealing system includes a flap. 
         FIG. 2B  represents the air extractor shown in  FIG. 2A  in which the flap is in a closed position. 
         FIG. 2C  represents the air extractor shown in  FIG. 2A  in which the flap is in an open position. 
         FIG. 2D  represents a variant of the first embodiment of the air extractor from  FIG. 2A  in which the flap is arranged at the inlet of the ventilation chamber. 
         FIG. 3A  represents an air extractor according to a second embodiment of the invention in which the sealing system includes at least one slat and in which the slat is in a closed position. 
         FIG. 3B  represents the air extractor shown in  FIG. 3A  in which the slat is in an open position. 
         FIG. 4  represents an air extractor according to a third embodiment in which the sealing system is a channel extending from the outlet of the ventilation chamber. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     The following terms are defined in the remainder of the description and may be understood in the following manner: 
     We define as the longitudinal direction the direction oriented from the front toward the rear relative to a motor vehicle, the adjectives front and rear being defined relative to the usual motion of the vehicle. We define as a transverse direction the direction perpendicular to the longitudinal direction and oriented from the right to the left of a motor vehicle. The two longitudinal and transverse directions define a horizontal plane. The vertical direction is perpendicular to the horizontal plane and oriented upwards. These same directions are used for the description of a headlight with the headlight considered as if it were positioned in a vehicle. 
     The adjectives “upper” and “lower” are also used relative to the vertical direction defined hereinabove. 
     The expression “external particles” denotes an element present in the external environment of the headlight and liable to reduce the performance of the components present in the headlight through contact therewith. External particles may include, nonlimitingly, dust, water, oil splashes, washing product splashes and leaves. 
     The concept of the invention is based on the use of an air extractor, arranged at the level of a headlight, enabling evacuation of hot air present in the headlight to replace it with cool air, to reduce the average temperature of the air inside a headlight and consequently the temperature of the components positioned inside the headlight. This principle is shown diagrammatically in  FIG. 1 , which represents a headlight  103  mounted on a motor vehicle  101  equipped with an air extractor  102  according to one embodiment of the invention. An air extractor  102  of this kind is advantageously fixed to the headlight  103  in a removable manner in order to enable replacement thereof in the event of failure. 
     The headlight  103  includes at least one optical module  105 . This optical module includes one or more temperature-sensitive components, including, for example, at least a component of the light spatial modulator type, a semiconductor component, an MEMS, a matrix of micromirrors, a liquid crystal screen or a laser. 
     This optical module advantageously includes a cooling system dedicated to the electronic component or components: however, because the optical module is integrated into a headlight including an air extractor according to one embodiment of the invention, which limits its average temperature, this dedicated cooling system may be simple and cooled only by conduction and by natural convection. The optical module therefore does not include a fan. It is therefore simplified compared to the usual optical modules including the same electronic components. The invention naturally remains compatible with these traditional optical modules including their own cooling system with a fan or fans. 
     By “natural convection” is meant convection that is not forced, that is to say produced without a fan or any other similar means enabling imposition of a flow of air locally in contact with or in the vicinity of the optical module. 
     The headlight  103  also includes an outer lens  106  arranged flush with or projecting from the bodywork  107  of the vehicle  101 . 
     The air extractor  102  is arranged on or through a wall of the headlight  103 . The air extractor is therefore able to provide fluidic communication between the interior and the exterior of the headlight  103 . The air extractor  102  is adapted to enable extraction of air from the interior the headlight  103  to the exterior of the headlight. In one embodiment, the headlight includes a headlight air inlet  104 . The hot air inside the headlight is therefore replaced by cooler air and the overall temperature of the air inside the headlight decreases. 
     The air extractor  102  is preferably arranged on the upper part of the headlight  103 . In fact, hot air being less dense than cold air, the air inside the headlight  103  is hotter in the upper part of the headlight  103  than in the lower part. Arranging the air extractor  102  in the upper part of the headlight  103  therefore advantageously enables extraction of the hottest air to the exterior of the headlight  103  and thus favours the reduction in temperature of the air inside the headlight. 
     In one embodiment, the air extractor  102  includes an air guide the inlet of which is arranged on the upper part of the headlight  103 . The air extractor  102  could then be arranged on a lower part or an intermediate part situated between the lower part and the upper part of the headlight  103 , the air guide enabling hot air situated in the upper part of the headlight  103  to be fed to the extractor. 
     In one embodiment, an air inlet  104  of the headlight  103  is arranged on the lower part of the headlight. The air inlet  104  of the headlight may be arranged on the lower surface  108  of the headlight. The air inlet  104  of the headlight is preferably situated below a horizontal plane passing through the air extractor  102 . 
     In one embodiment, the air inlet  104  of the headlight is arranged on the front part of the headlight  103 , that is to say the part nearest the outer lens  106  of the headlight  103 . This kind of arrangement of the air inlet  104  of the headlight advantageously enables cooler air to enter the interior of the headlight  103 , in particular by moving the air inlet  104  of the headlight farther away from the engine of the vehicle  101 , generally situated to the rear of the headlight  103 . 
     In one embodiment, the air inlet  104  of the headlight includes an air guide the inlet of which is arranged on the front part and/or on the lower part of the headlight  103 . 
     The air inlet  104  of the headlight may include an air filter. The air filter advantageously enables air to flow from the exterior to the interior of the headlight  103 , preventing external particles from penetrating to the interior of the headlight  103  via the air inlet  104  of the headlight. 
     An example of an air extractor  201  according to a first embodiment is described hereinafter with reference to  FIGS. 2A, 2B and 2C . 
     The air extractor  201  includes an air inlet  203  and an air outlet  214 , shown more particularly in  FIG. 2C . The air extractor  201  also includes 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  includes a fan  202 . By fan is meant any means for generating a flow of air between the air inlet  203  and the air outlet  214 . 
     The fan  202  may 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 air outlet at a velocity substantially equal to 5 metres per second. In one embodiment, the fan  202  is designed to generate a flow of air at the air outlet between 100 and 500 L/min inclusive. 
     As shown in  FIG. 2B , the air extractor  201  is arranged in the rear and upper part of a headlight  213 , in a manner similar to the  FIG. 1  diagram. The air inlet  203  is adapted to be positioned inside the headlight  213 . The air outlet  214  is adapted to be outside the headlight  213 . The fan  202  therefore enables aspiration of internal hot air inside the headlight  213  via the air inlet  203  and expulsion thereof to the exterior of the headlight  213  and the air outlet  214  of the air extractor. 
     The air extractor  201  also includes a system sealing at least against external particles. In one nonlimiting embodiment, the sealing system is also airtight. The sealing system against external particles enables external particles present in the air outside the headlight  213  to be prevented from penetrating to the interior of the headlight  213  when the fan is turned off or when the fan is not activated. 
     In fact, when the air extractor  201  is operating, a through-flow of air is generated from the air inlet  203  to the air outlet  214  of the air extractor  201 . This through-flow of air prevents external particles from passing through the extractor to the interior of the headlight. However, if the fan  202  is turned off no flow of air is generated and it is therefore important, for the preservation of the components present in the headlight, to close the extraction system in order for no dust to enter the headlight via the air extractor. 
     In one embodiment, the air extractor does not include an air filter, which prevents creation of too high a resistance to the flow of air. 
     A first example of a sealing system is shown in  FIG. 2A . In this first embodiment, the sealing system includes a blocking means  206 . The blocking means  206  may be situated in the ventilation chamber  210 , in the air inlet  203  or in the air outlet  214 . The blocking means  206  may be a flap covering the entire section of the air extractor. 
     The blocking means  206  is designed to be able to assume or to be able to move between two positions: an open position ( FIG. 2C ) allowing fluidic communication between the air inlet and the air outlet of the air extractor and a closed position ( FIG. 2B ) for preventing at least the passage of external particles between the air outlet and the air inlet. 
     In one embodiment, the blocking means  206  is mobile between two limit positions: the closed position and the open position. 
     In the closed position, the blocking means  206  may cover a section of the air extractor so as to prevent at least external particles from passing through that section. Said section may be situated in the ventilation chamber  210 , in the inlet or in the outlet of the air extractor. 
     The blocking means  206  may be a flap made from a gastight material or a material permeable to air and sealed against external particles. 
     The blocking means  206  may be mobile between a closed position ( FIG. 2B ) and an open position ( FIG. 2C ) by a movement in translation or by a system of slat(s). 
     The air extractor  201  may also include an air guide  204 . The air guide  204  enables fluidic connection between the air inlet  203  of the air extractor and the ventilation chamber  210 . The air guide  204  therefore enables the provision of an air extractor  201  including an air inlet  203  oriented toward the upper side of the extractor. This air guide  204  therefore advantageously enables placement of the air inlet  203  toward the top of the headlight. In this way, the air guide  204  allows aspiration of air from the headlight in the highest possible position, and thus the hottest air  211 , rather than the cooler air  212  present in the lower part of the headlight  213 . The air guide  204  includes a channel or a longitudinal pipe. In the embodiment, the air guide  204  makes it possible to form a tortuous path for the air, which also contributes to limiting the possible passage of any external particles from the exterior to the interior of the headlight, and therefore contributes to the sealing function. 
     The air extractor  201  may also include seals  208  to guarantee a seal between the extractor  201  and the headlight  213  and/or between the walls of the extractor  201  and the blocking means  206 . 
       FIG. 2D  shows a variant of the first embodiment in which the blocking means  206  is disposed at the inlet of the ventilation chamber  210 . The two variant embodiments may equally be combined. 
     In this first embodiment, the headlight further includes a control device  209  of the air extractor  201 , represented in  FIGS. 2A and 2D . This control device may include an activator, adapted to control the opening and the closing of the at least one blocking means  206 . The activator  209  may include a motor or a driven arm enabling movement of the blocking means  206 . The control device may further include a processor  207  and/or a printed circuit. The processor may be connected to the activator  209  by a communication means in order to control the blocking means via the activator. 
     The control device is configured to trigger operation of the air extractor when the engine of the vehicle  101  is started and to stop it when the engine is stopped. 
       FIGS. 3A and 3B  represent an air extractor  301  according to a second embodiment, in a closed configuration and in an open configuration, respectively. 
     In this embodiment, the air extractor  301  includes at least one blocking means  306  mobile in rotation. In particular, the blocking means  306  may be mobile in rotation about a pivot  309  oriented in the transverse direction. This blocking means  306  is designed, when in the closed position represented in  FIG. 3A , simultaneously to close the inlet and the outlet of the ventilation chamber  310 . When in the open position represented in  FIG. 3B , it simultaneously opens the inlet and the outlet of the ventilation chamber  310 . Alternatively, this blocking means could open and close the air inlet  303  and the outlet  314  of the air extractor  301 . 
     The blocking means  306  is of sufficient length on either side of the pivot  309  so as, when in the closed position, to be able 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 seals  308  disposed between the pivot  309  and the wall  313  of the headlight. The extractor  301  may equally include a seal  308  between the ventilation chamber and the walls of the headlight. 
     The blocking means  306  may include a surface  305  sealed against external particles and permeable to gases. 
     The air extractor  301  further includes an air guide  304  designed so that the air inlet of the extractor  303  is oriented upward or toward the upper face of the headlight  313 . The extractor  301  is therefore able to aspirate the hottest gases  311  rather than the cooler gases  312  situated in the lower part of the headlight. 
     In a third embodiment illustrated by  FIG. 4 , an air extractor  401  likewise includes an air inlet  403  and then an air guide  404  leading to a ventilation chamber  410  equipped with at least one fan  402 . In this embodiment, the sealing system includes an outlet channel  405  having at least one bend. This outlet channel  405  having at least one bend is arranged between the ventilation chamber  410  containing the fan  402  and the air outlet  414  of the air extractor  404 . Alternatively, the outlet channel  405  may include a plurality of bends. Said outlet channel  405  preferably includes a bend between 150° and 200° inclusive, that is to say it guides the air extracted by the air extractor  401  along a path including this kind of sharp bend before it exits the extractor. A curve of this kind, around substantially 180°, enables the air channel  405  to orient the air outlet  414  toward the rear wall of the headlight  413 . The air outlet  414  is therefore not oriented toward the engine of the vehicle. This orientation makes it impossible or very difficult, when the fan is switched off, for external particles to penetrate to the interior of the headlight via the air extractor. The outlet channel  405  therefore provides the sealing function. Alternatively, the sealing system could be implemented by any other channel having at least one bend, not necessarily positioned at the level of the outlet of the air extractor. 
     In one embodiment, the outlet channel  405  further includes a filter or a grille  415  in the vicinity of the air outlet  414 . This grille makes it possible to slow or to stop external particles, which will tend to be deposited on this grille rather than to follow the path through the outlet channel  405 . 
     The grille  415  covers the section of the outlet channel  405 . The grille preferably covers the entirety of the section of the outlet channel  405  at the level of the arrow  414 . The grille preferably includes a succession of slats or filaments. The spacing between adjacent slats or between adjacent filaments is between 0.5 and 3 mm inclusive. 
     The outlet channel  405  preferably further extends over a sufficient length to provide the seal of the air extractor  401  against the external particles. The outlet channel  405  may extend over a length at least greater than 25 mm and/or less than 200 mm. 
     The diameter or the width of the section of the outlet channel  405  may be between 15 and 50 mm inclusive. The dimensions of the section of the outlet channel  405  contribute to sealing the air extractor  401  whilst allowing the passage of the flow of air when the fan  402  is operating. 
     The advantage of this solution is that it dispenses with the use of mechanical devices such as mobile blocking means, such as slats. This solution may advantageously also dispense with the air filter. 
     The outlet channel  405  may equally be designed so that, once mounted on the headlight  413  and on a vehicle, it has a slope so that any water present in the outlet channel, for example after spraying water or through condensation, is evacuated by gravity via the air outlet  414  of the extractor  401 . When the air extractor is mounted on a headlight on a vehicle, the air outlet  414  is advantageously arranged at a lower height than the air outlet of the ventilation chamber  410 . 
     In a complementary manner, in all the embodiments the ventilation chamber is designed to have a slope relative to a horizontal plane. Once the extractor is mounted on a headlight of a vehicle, this slope allows an outlet flow of water over the walls of the ventilation chamber without penetrating into the headlight. As represented in  FIGS. 2A to 4 , the upper part of the ventilation chamber, disposed outside the headlight, has a slope relative to a horizontal plane so as to evacuate water. In these embodiments, water is not able to stagnate in the air extractor or penetrate into the interior of the headlight. 
     The invention is not limited to the embodiments described. For example, other embodiments may be obtained by eliminating the air guide of these embodiments, which remains optional. Also, any other blocking means may be envisaged. For example, a slat may be mobile with a movement other than a movement in translation or in rotation, or with a movement in translation in a direction other than that described for the first embodiment, or in rotation about an axis oriented in a direction other than that described for the second embodiment. 
     Also, the at least one blocking means may include at least two or a plurality of slats. In this case, the various slats are configured to effect a synchronized movement in rotation. Each slat is arranged so that, when in the closed position, it covers a part of the section of the air extractor. The slats are such that, when they are all in the closed position, they together cover the entirety of the section of the air extractor. For example, in one embodiment, the at least one blocking means includes a double slat. 
     Also, in all the embodiments, the air extractor includes a control device such as that described with reference to the first embodiment. 
     That control device may moreover implement a method for extraction of air from a headlight, including in particular a method of activating the air extractor, triggered automatically on starting the motor vehicle and stopped automatically on stopping the engine of the motor vehicle. The headlight and/or the air extractor therefore includes a mobile blocking means and includes hardware and/or software elements for implementing the air extraction method. 
     In an embodiment associated with a mobile slat air extractor, as in accordance with the first or the second embodiment of the invention, the method of activating the air extractor advantageously includes the following steps:
         activating the fan, then   moving the blocker or the at least one blocker to reach an open position.       

     The movement step is preferably executed at least one second, preferably at least three or four seconds, most preferably between three and six seconds after the execution of the activation step. In this way, activation of the fan brings about the pressurization of the ventilation chamber before the blocking means is opened. This increased pressure advantageously makes it possible to guarantee that no dust can enter the interior of the headlight via the extractor when it is started up. 
     The step of activating the fan may be preceded by a step of receiving a control signal, for example a signal generated when the engine is switched on, is powered up. 
     Similarly, the method for deactivating the extractor includes the following steps:
         moving the blocking means into the closed position,   deactivating the fan.       

     The deactivation step is preferably executed at least one second, preferably at least three or four seconds, most preferably between three and six seconds after executing the movement step. In this way it is possible to guarantee that no dust is able to enter the interior of the headlight via the extractor when it is turned off. 
     The movement step may be preceded by a step of receiving a control signal, for example a signal generated when the engine is turned off, is powered down.