Abstract:
The invention relates to a headlight ( 100 ) for a two-wheeled vehicle ( 1 ), including at least one light source combined with at least one reflector for reflecting the light from the light source in the traveling direction of the vehicle (e 1 ), characterized in that the headlight has a rotational axis about which it can pivot, said axis extending, when the headlight is in a reference position corresponding to a position in which the vehicle is substantially vertical and not inclined, in a substantially median and vertical longitudinal plane (e 1 , e 3 ) of the headlight, the rotational axis further being inclined relative to the vertical direction.

Description:
TECHNICAL FIELD 
     The present invention relates to a headlight for a two-wheeled vehicle, in particular a motorcycle, as well as a two-wheeled vehicle equipped with such a headlight. 
     BRIEF DESCRIPTION OF RELATED ART 
     Motorcycle headlights are designed to meet safety standards when the motorcycle is moving in a straight line and is kept substantially on the vertical of the road. 
     When the motorcycle undertakes a turn, the driver turns the handlebars and tilts the motorcycle. As a result, the headlight is no longer oriented in an optimal direction. The illumination of the road in the direction in which the motorcycle is oriented is thereby greatly reduced, which presents an obvious danger, in particular at night, when the driver&#39;s field of vision is extremely reduced as a result, and does not facilitate anticipation of the path (end of the turn, oncoming vehicles, obstacles, holes, etc.). 
     This problem is well known, and builders have sought to develop numerous solutions making it possible to optimize the orientation of the headlight as a function of the direction assumed by the motorcycle. 
     Known in particular are front illumination systems with three lights comprising a central headlight, designed to illuminate the road when the motorcycle is traveling in a straight line, and two side headlights, situated on either side of the central light, and designed to illuminate the road when the motorcycle is inclined, the headlight on the side where the motorcycle is inclined being lit to complete the illumination area of the central headlight. 
     Of course, such a system does not precisely account for the incline angle of the motorcycle and is based on an average incline angle up the heart of a standard turn. 
     Builders as well as institutions/universities have therefore conducted many studies to develop dynamically multi-directional headlights using actuators as a function of the incline angle of the motorcycle and potentially other parameters. It should be noted that at this time, there is no commercial solution, and the current solutions are rather based on sets of mirrors or multi-directional masks. 
     Aside from the relative bulk of the means for actuating and controlling headlights, a major problem in this type of system is the real-time measurement of those parameters, and in particular measurement of the incline angle of the motorcycle. 
     Traditionally, a gyroscopic sensor is used to measure the incline of the motorcycle and deduce therefrom the correction to be applied to the orientation of the headlight. 
     Recent technological developments have made it possible to introduce MEMS accelerometer and gyroscopic sensors, which are less expensive and more reliable. The mechanical part of orienting the headlight remains relatively complex, however, which is a potential source of numerous breakdowns and failures of the system, limiting the practical implementation of such products. 
     For more information on measuring the incline angle, reference may be made, inter alia, to the following articles:
         On Navigation Systems for Motorcycles: The influence and Estimation of Roll Angle (2005)—USA, Department of Mechanical Engineering, University of California. THE JOURNAL OF NAVIGATION (2005), 58, 375-388.   A Study on Motorcycle AFS Visibility and Glare (59 th  GRE, Mar. 31-Apr. 4, 2008)—Japan.   Corner Adapting Motorcycle MIM 1501-1502. Technical Design Report (May 29, 2002) Department of Mechanical, Industrial and Manufacturing Engineering, College of Engineering, Northeastern University, Boston, Mass. 02115.       

     It has also been observed that the correction angle of the headlight must at most be equal to the incline angle of the two-wheeled vehicle, and preferably slightly smaller. 
     Thus, to make the headlight horizontal again in a turn, it is necessary to apply a rotation thereto around an illumination and travel direction of the vehicle by an angle substantially equal to the incline angle of the motorcycle, and in any case to remain smaller than that angle. 
     This is the recommendation of the aforementioned Japanese study for speed conditions comprised between 30 and 60 km/h and turn radii of 30 to 140 m. 
     The study does not, however, mention a correction in the direction of the beams of light in the horizontal plane, in particular by orienting the headlights slightly toward the inside of the turn so as to better illuminate the portion of the road toward which the motorcyclist is traveling, and suggests that acting on the incline alone is sufficient. 
     It is, however, possible, in many cases, and even at reduced speeds, for the incline angle to be much larger, in particular greater than 40°, and for a significant direction correction in the horizontal plane to be necessary. 
     This direction correction must therefore be able to be done at the same time as the incline correction of the headlight. It will be noted that a pitch correction may also be necessary. 
     This generally results in the design of particularly complex, relatively bulky lighting correction means, which are therefore relatively expensive. It follows that such systems are difficult to incorporate into more modest two-wheeled vehicles such as scooters, mopeds, entry-level motorcycles, etc. 
     It will also be noted that the current actuating systems generally depend on the type of headlight used (elliptical, parabolic, etc.), and that there is a need for a system that is easily adaptable to all types of headlight. 
     BRIEF SUMMARY 
     The present invention aims to propose a multi-directional headlight benefiting from a simpler and more reliable mechanical system. 
     To that end, the present invention relates to a headlight for a two-wheeled vehicle, including at least one light source combined with at least one reflector for reflecting the light from the light source in the traveling direction of the vehicle, the headlight having a rotational axis around which it can pivot, said axis extending, when the headlight is in a reference position corresponding to a position in which the vehicle is substantially vertical and not inclined, in a substantially median and vertical longitudinal plane of the headlight, the rotational axis further being inclined relative to the vertical direction, characterized in that it comprises at least one actuator capable of rotating the headlight around its axis. 
     In this way, by providing a headlight having an axis of rotation situated in a substantially median longitudinal plane of the headlight and inclined relative to the vertical direction, a rotation of the headlight around that axis will cause a simultaneous correction of the incline angle of the vehicle and the projection direction of the light. The combination with driving means also allows precise driving of the headlight, in particular using a controller combined with sensors. 
     Preferably, the incline angle of the axis of rotation is comprised between 20 and 45°. 
     Also preferably, the incline angle of the axis of rotation is substantially equal to 45°. 
     In fact, with a primary axis of rotation substantially inclined at 45°, the corrections made to the incline and the projection direction of the light are substantially identical. A variation in the angle of the primary axis of rotation will make it possible to define an appropriate and optimal simultaneous correction relationship for these two angles according to the concerned vehicle. 
     It will also be noted that the correction can be done with a single actuator and with a relatively modest amplitude. The construction and control of the headlight are therefore greatly simplified, and the final cost is reduced. 
     Additionally advantageously, the headlight has a second axis of rotation around which it can pivot, said second axis of rotation being oriented, when the headlight is in its reference position, in a substantially median plane of the substantially horizontal headlight and in a direction substantially transverse to the projection direction of the light. The possibility of rotation around this second axis allows a possible correction of the pitch if necessary. 
     Also additionally advantageously, the headlight has a third axis of rotation around which it can pivot, said third axis of rotation being oriented, when the headlight is in its reference position, in a substantially vertical direction of the headlight. 
     Preferably, the headlight comprises at least one means for rotating the headlight around the second and/or third axis of rotation. 
     Advantageously, the means for rotating around the axes are rotary and/or linear actuators with a low amplitude, preferably rotary. The rotary actuators are less expensive and more reliable. 
     Additionally, the headlight comprises at least one diaphragm. More specifically, it may be a high beam or low beam or both by means of said diaphragm. 
     Advantageously, the headlight comprises at least one microcontroller capable of controlling the actuator(s) as a function of input parameters such as the speed of the vehicle and the incline angle of said vehicle. 
     Alternatively, this microcontroller and the sensors may belong to the vehicle. 
     According to alternative embodiments, the headlight comprises at least one gyroscopic sensor and/or at least one inclinometer. 
     It will also be noted that the headlight may indifferently be of the elliptical or parabolic type. 
     The present invention also relates to a two-wheeled vehicle, in particular a motorcycle, characterized in that it comprises at least one headlight according to the invention. 
     The term “two-wheeled vehicle” does not exclude vehicles of the three-wheeled scooter type, the issue of the incline on turns also applying to that type of vehicle. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The present invention will be better understood in light of the following detailed description in reference to the appended drawing, in which: 
         FIG. 1  is a diagrammatic illustration of a motorcycle inclined in a turn with its associated three-dimensional reference, 
         FIG. 2  is a diagrammatic illustration of a headlight and its correction axes, 
         FIG. 3  is an overall view of the orientation axes of the headlight of  FIG. 2 , 
         FIGS. 4 to 7  show example embodiments of headlights according to the invention, and 
         FIG. 8  is a diagrammatic illustration of a control chain of a headlight according to the invention. 
     
    
    
     DETAILED DESCRIPTION 
       FIG. 1  is a partial view of a motorcycle equipped with a headlight  100  according to the invention. The motorcycle  1  is inclined in a turn, and its associated three-dimensional reference {e 1 , e 2 , e 3 } has been shown in dotted lines and solid lines, respectively corresponding to the reference when the motorcycle  1  is upright and when the motorcycle  1  is inclined. 
     The axis e 1  corresponds to a direction of travel of the motorcycle, and is therefore not modified by the incline. However, it also represents the projection direction of the light from the headlight, direction which, in a turn, should be corrected by an angle α. 
     The axis e 2  corresponds to a direction transverse to the motorcycle  1 . When the motorcycle  1  is upright, the axis e 2  substantially corresponds to a horizontal direction. When the motorcycle  1  is inclined in a turn, the axis e 2  undergoes a rotation by an angle β around the axis e 1 . 
     The axis e 3  corresponds to a substantially vertical direction when the motorcycle  1  is upright. When the motorcycle  1  is inclined in a turn, the axis e 3  is inclined by an angle φ (roll angle). 
       FIG. 2  is a detailed view of the headlight  100  and axes previously defined on which the necessary corrections according to the invention have also been marked. 
     As previously explained, it is recommended for the compensation correction made to the headlight according to the angle β to be substantially equal to the incline angle φ of the motorcycle  1 , or slightly smaller. A correction according to the angle α is also necessary. 
     In order to simply and effectively make the necessary corrections according to the invention, the headlight  100  has an axis of rotation R (thick arrow) inclined relative to the vertical axis e 3 . In the case at hand, the axis R is inclined by 45° relative to e 3 . 
     By rotating the headlight around the axis R by an angle δ, compensation will be done both on the angles α and β. 
     It will be noted that with an axis of rotation R of the headlight  100  inclined at 45°, the corrections made will be the angles α and β will be identical. 
     A modification in the incline of the axis of rotation R of the headlight  100  will make it possible to change this correction ratio between β and α as a function of the considered vehicle to obtain an optimal correction. 
     In the case at hand, the angle δ=φ/0.7 (in this case), with an axis of rotation R inclined by 45° (α=β=φ), and a single actuator, preferably rotary, makes it possible to perform this double correction. 
     As a function of the vehicle and if necessary, it may also be interesting to take the pitch of the vehicle  1  into account and correct it. In fact, when the motorcycle  1  is inclined, the height of the headlight  100  relative to the ground is reduced. As a result, the portion of the path illuminated in front of the motorcycle  1  is also reduced and that pitch should be corrected. Furthermore, the distance between the motorcycle and the location to be illuminated depends significantly on the curvature (radius) of the turn and the speed of the motorcycle. 
     To that end, according to one additional aspect of the invention, the headlight  100  has a second axis of rotation R′, substantially parallel to e 2  and passing through an intersection of the rotary axis R with a center line of the headlight substantially parallel to e 1 , around which it will be pivoted by a compensation angle ε. 
     In general, such a correction remains limited and a rotary or linear actuator with a small amplitude may be used. 
     As a function of the bulk and the available space, the correction actuator for the pitch may be positioned on a structure of the motorcycle  1  or in the headlight  100  itself. 
     All of the axes and corrective angles are shown in  FIG. 3  without a headlight  100 . 
       FIGS. 4 to 7  show example embodiments of headlights according to the invention. 
       FIG. 4  shows a first example embodiment of a headlight  101  according to the invention with an axis of rotation R inclined by 40°. 
     The headlight  101  is held by a foot  102  rotatably mounted on a platen  103  such that the axis of rotation R is inclined by 40° relative to the vertical. 
     The platen  103  supports means for rotating the foot  102 , and therefore the headlight  101 , around the axis R. 
     These driving means comprise a rotary actuator  104  having axle capable of driving a toothed wheel  105  rotatably meshing with a toothed wheel  106  of the foot  102 . 
     Of course, any alternative driving solution is possible, in particular driving using a belt, for example. 
       FIG. 5  shows the headlight of  FIG. 4  on which a correction of the pitch is provided. To that end, the headlight  101  is associated with a second rotary actuator  107  capable of rotating a toothed arm  108  making it possible to tilt the headlight  101  around a transverse axis. 
       FIG. 6  shows an alternative embodiment in which a linear actuator  109  with a small amplitude pulls or pushes an associated arm  110  also so as to tilt the headlight  101  around a transverse axis. 
     It will be noted that one primary advantage of the correction of the pitch lies in being able to offset a change in the illumination area due to a modification in the attitude of the vehicle, in particular in case of braking or acceleration. 
       FIG. 7  shows another example embodiment of a headlight  200  according to the invention in which the headlight  200  has a third axis of rotation R″ around which it can pivot, said third axis of rotation R″ being oriented, when the headlight is in its reference position, in a substantially median plane of the substantially vertical headlight and in a substantially vertical direction. 
     The example of  FIG. 7  only shows an adjustment around the first and third axes, the pitch angle not having been corrected. This nevertheless remains possible. 
     The headlight  200  is rotated around said axis R″ by a rotary actuator  201  and driving wheels  202 ,  203 , mounted on the foot  102  of the headlight  200 . 
     In addition to the other axes of rotation R and R′, this third axis of rotation R″ allows a correction in all directions. In particular in the illustrated example, a correction of both the incline (φ) and the direction of the light beam (α) is made possible. 
       FIG. 8  diagrammatically shows the arrangement of a control chain for a headlight according to the invention. 
     This control system is built around a microcontroller  300  capable of receiving speed and incline values from a gyroscopic MEMS sensors  302 , an inclinometer  300  and a speed sensor  303 . 
     It should be noted that the only information the microprocessor of the controller needs is the speed and the levels of the angles of rotation. The inclinometer is used when the speed of the motorcycle is zero and it does not operate when the motorcycle is traveling. However, it is used to correct the incline angle when the motorcycle tilts while stopped (red light or other reason, for example). 
     The yaw level, roll level, possibly pitch level, and speed are thus provided to the microcontroller  300  as parameters so that the latter can compute and send, as output, the appropriate commands to the corrective actuators  109  and  104 . 
     Of course, this control change is provided solely as an example and must be adapted as a function of the headlight used according to the invention and the parameters necessary to determine the corrections. 
     In a known manner, integrating the roll level makes it possible to obtain the incline angle φ of the vehicle. This integration does, however, risk adding a growing error in the time, and the angle φ may be calibrated by the yaw rate and the speed and/or by the absolute signal from the inclinometer  301 . 
     Using the incline angle φ, it is possible to compute the curve radius of the turn and to determine, using the speed of the vehicle, the ideal correction according to the angle α. 
     Although the invention has been described with one particular embodiment, it is of course in no way limited thereto and encompasses all technical equivalents of the described means as well as combinations thereof if they are within the scope of the invention.