WO2020065076A1

WO2020065076A1 - Device for protecting an optical sensor/transmitter of a driver assistance system for a motor vehicle

Info

Publication number: WO2020065076A1
Application number: PCT/EP2019/076322
Authority: WO
Inventors: Frédéric BRETAGNOL; Marcel Trebouet; André Rey; Quentin FROSSARD; Sébastien-Victor ROCHE; Aurélien COUAVOUX
Original assignee: Valeo Systèmes d'Essuyage
Priority date: 2018-09-27
Filing date: 2019-09-27
Publication date: 2020-04-02
Also published as: FR3086769B1; FR3086769A1

Abstract

The invention concerns a device (4) for protecting an optical sensor/transmitter (2) of a driver assistance system for a motor vehicle, in which a first sub-assembly (B) comprises a protective housing (8) capable of at least partially accommodating the optical sensor/transmitter (2), the protective housing comprising an optical element (12) arranged opposite the optical sensor/transmitter (2), and in which a second sub-assembly (C) comprises a motor (14) configured to rotate the first sub-assembly (B) about an axis of rotation (A1). According to the invention, the first sub-assembly (B) and the second sub-assembly (C) are linked via reversible retaining means (40).

Description

PROTECTION DEVICE FOR AN OPTICAL SENSOR / TRANSMITTER OF A DRIVING ASSISTANCE SYSTEM FOR A MOTOR VEHICLE

The present invention relates to the field of driving assistance and in particular to driving assistance systems, installed on certain vehicles, the driving assistance system possibly comprising an optical sensor / transmitter, such as for example a camera including a lens. More particularly, the invention relates to a protective housing of such an optical sensor / transmitter.

Currently, optical sensors / transmitters and, for example, front, rear or even side vision cameras, equip a large number of motor vehicles. They are notably part of driving assistance systems, such as parking assistance systems, or line crossing detection systems. In order to best detect the obstacles situated all around the vehicle, it is known to install the optical sensors / transmitters of the driving assistance systems on the periphery of the vehicles in different places according to the desired use, for example integrated in the rear or front bumpers, in the side reinforcement strips, or at the rear or front registration plate of the vehicle.

In this case, the optical sensors / transmitters are highly exposed to splashes of mineral or organic dirt which can deposit on the corresponding optical surface and thus reduce the efficiency of signal transmission, shooting or detection of information, or even make the sensor / transmitter, detector, or camera concerned totally inoperative. In particular in rainy weather, projections of rain and dirt can be observed which can greatly affect the operability of the driving assistance system comprising such an optical sensor / transmitter.

It is therefore understood that the optical surfaces of the sensors / transmitters must be cleaned in order to guarantee their good operating condition, and this need is all the more important in the case of an autonomous vehicle, in which the control of the vehicle is carried out through the information sent and / or collected by the sensors / transmitters.

It is thus known to arrange a device for cleaning the optics of the sensor / transmitter near this optics in order to remove the polluting elements which have deposited there beforehand. In particular, the cleaning devices can consist of nozzles supplied with cleaning fluid. Where appropriate, these nozzles can be arranged at the end of a telescopic device configured to pass from a retracted rest position to a deployed cleaning position. If the use of these nozzles allows proper cleaning of the sensors / transmitters, it generates significant operating costs because it is necessary to provide fairly large quantities of cleaning fluid and sophisticated means of kinematics of the nozzle.

Alternatively, it is known to provide cleaning devices comprising on the one hand a protective glass, arranged facing the optical surface of the sensor / transmitter so that the dirt is deposited on this glass and not directly on the optical surface, and on the other hand vibration means which are controlled to vibrate the protective glass in order to peel off the dirt. However, it has been found that the effectiveness of such a device for stubborn and encrusted soiling can be limited despite the vibration of the protective glass.

Another alternative provides that a sensor / transmitter, and more particularly a camera, of a driving assistance system is associated with a protection device which comprises a protective housing housing the sensor / optical transmitter while protecting it from the outdoor environment. The protective housing comprises an optical element, transparent and arranged opposite the optical surface of the sensor / transmitter to allow the transmission and / or acquisition of data. The protective housing and the associated optical element are rotated by a motor forming part of the protective device. More specifically, the motor is configured to drive rotation of the protective housing at a speed sufficient to remove by centrifugal effect dirt or water which may be present on the optical element. This centrifugal cleaning solution is much more effective than the vibration of the optical element described above. The rotational speeds necessary for effective centrifugal cleaning are of the order of 10,000 rpm. At this speed, the rotary part of the motor and the protective casing should be secured and there should be no risk of detachment as the casing relative to the subassembly comprising the actuator. It can in particular be provided to form a peripheral skirt of the housing configured and dimensioned to be inserted and held by welding in a peripheral groove of corresponding shape of the rotary part of the motor. Although effective with regard to the rotational drive of the housing, this configuration has the drawback of having to replace the entire protective device, that is to say the subassembly comprising the protective housing and the sub-assembly comprising the motor, when it is desired, for example, to change only the optical element in the event of an impact on its surface, or else to replace the optical sensor / transmitter.

The present invention proposes to solve this technical problem, by presenting an alternative to the protection devices of a known optical sensor / transmitter, allowing easier maintenance, and therefore less costly, of the protection device and of the elements present in said housing. , while ensuring reliable long-term drive of the rotating protective housing.

To this end, the subject of the invention is a device for protecting an optical sensor / transmitter of a driving assistance system for a motor vehicle, in which a first sub-assembly comprises a protective box capable of receiving at least part of the optical sensor / transmitter, said protective casing comprising an optical element disposed opposite the optical sensor / transmitter and in which a second sub- assembly includes a motor configured to rotate the first sub-assembly about an axis of rotation.

The invention is remarkable in that the first sub-assembly and the second sub-assembly are linked by means of reversible holding means. In other words, the holding means are capable of allowing rapid assembly and disassembly, between the first and the second subassembly making up the protection device. Thus, advantageously, the invention allows easier maintenance and therefore less costly of the protection device, by allowing the change of only part of the protection device in the event of failure, and no longer the whole of the protection device. protection. This is in particular particularly advantageous when it is a question of changing the optical element, and therefore the protective casing of which it is integral, it being understood that this optical element is arranged opposite the optical sensor / emitter to protect it from dirt and impacts and can therefore be degraded or soiled irreversibly, which requires its replacement, without it being necessary to dismantle the second sub-assembly. In this way, the motor and the optical sensor / transmitter can be left in place.

In one aspect, the protection device is a separate element from the optical element.

According to an alternative, the protection device is part of the optical element. According to different characteristics of the invention, taken alone or in combination, it can be provided that according to a first embodiment:

- The reversible holding means comprise a set of threads configured to cooperate with each other and allow the first sub-assembly to be screwed on, comprising a first thread on the second sub-assembly, comprising a second thread. - The first thread of the first sub-assembly is produced on an internal face of a peripheral wall of the protective housing, in the vicinity of an opposite axial end to the optical element. By "internal face" is meant a face of the protective housing facing the cavity which it participates in defining to house the optical sensor / transmitter.

- The second thread of the second sub-assembly is produced on an external face of a cylindrical wall projecting from a flange extending the rotor of the motor opposite to it.

- The cylindrical wall and the flange form part of an intermediate piece made integral in rotation with the motor rotor.

- The sub-assemblies are characterized so that the cylindrical wall and the peripheral wall overlap at least partially for the screwing of the first sub-assembly on the second sub-assembly.

According to a characteristic of the invention, the protection device comprises a control unit configured to control the power supply to the motor, so as to allow rotation of the first sub-assembly, and of the protective housing which it comprises, of the '' order of 10,000 rpm. In this context, the protection device according to the invention is such that the reversible holding means comprise a securing system configured to prevent the protective casing from being able to unscrew from the second subassembly when the casing is rotated. motor protection.

More particularly, the motor and the threads can be configured so that the motor rotates the first sub-assembly, in the same direction as the direction of screwing between the first sub-assembly and the second sub-assembly. It is understood that the direction of screwing between the two sub-assemblies is determined by the orientation of the direction of the first and second threads. Thus, when we look at the protection device from the rear of it, that is to say opposite the optical element, threads are produced in the form of a right-hand thread when the engine is configured to rotate the first sub-assembly clockwise. Alternatively or cumulatively, the securing system may include a latching device making it possible to ensure the axial position of the subassemblies relative to one another when they are at the end of screwing.

According to a characteristic of the invention, the reversible holding means comprise at least one device for axial positioning of the protective housing. The aim is thus to ensure the correct axial position of the protective housing. It is understood that this characteristic is important here in that the reliable position of the optical element is part of an optical context of transmission and / or acquisition of data by the optical sensor / transmitter through the optical element.

This axial positioning device may in particular comprise a mechanical abutment face carried by the second sub-assembly. The aim is thus to ensure the correct axial position of the protective housing, which can be removed at each necessary intervention on the optical element for example and which can be replaced or replaced by another protective housing, compared to the second sub-assembly which remains fixed during these interventions. The mechanical stop face makes it possible to return to the original position of the protective housing before intervention by forcing the screwing of the two sub-assemblies until arriving at the axial stop. As soon as the assembly of the optical sensor / transmitter in the protection device is such that the position of the optical sensor / transmitter, and therefore of its optical surface, is known with respect to the mechanical stop face formed by the second sub- assembly, which remains in place during the replacement of the first sub-assembly, the position of the optical element relative to the optical surface of the sensor / transmitter can be precisely ensured by abutting the protective housing against the face of mechanical stop.

The mechanical abutment face carried by the second sub-assembly can in particular be produced by a face of the flange, the cylindrical wall of which extends projecting.

According to a characteristic of the invention, the reversible holding means comprise a device for radial centering of the first subassembly relative to the second subset. The aim is thus to ensure the correct radial position of the protective housing. More particularly, the aim is to ensure that the optical element carried by the protective housing is correctly centered on the optical axis of the optical sensor / transmitter, or at the very least positioned in accordance with the desired theoretical position. Again, it is understood that this characteristic is important here in that the reliable position of the optical element is part of an optical context of transmission and / or acquisition of data by the optical sensor / transmitter through the optical element.

The radial centering device can comprise at least one inclined plane formed by a shoulder of the cylindrical wall of the second sub-assembly and / or by a shoulder of the peripheral wall of the protective housing.

According to another characteristic of the invention, the reversible holding means also comprise a sealing means arranged between the first sub-assembly and the second sub-assembly. The sealing means may in particular comprise a seal disposed in a groove formed around the entire periphery of the internal face of the protective housing and / or of the external face of the cylindrical wall of the second sub-assembly.

The radial centering device and / or the sealing means can be located axially between the threads and the mechanical stop face of said axial positioning arrangement. According to an alternative embodiment, the reversible holding means differ from the first embodiment in that they comprise a set of fixing means configured to cooperate with one another and allow the latching of the first sub-assembly, comprising at least one member fixing having the shape of a female organ, on the second sub-assembly comprising a fixing element having the shape of a male organ.

The fixing member is produced on an internal face of a peripheral wall of the protective housing, in the vicinity of an axial end opposite the optical element. The fixing member having the shape of a female member capable of receiving a male element of complementary shape. This can be at least one annular groove, at least one point housing or at least one hook.

The fastening element is produced on an external face of a cylindrical wall projecting from a flange extending the rotor of the motor opposite it.

The fixing element may be at least one annular protuberance, at least one point stud, or at least one fixing lug.

The cylindrical wall and the flange form part of an intermediate piece made integral in rotation with the motor rotor.

The sub-assemblies are characterized in such a way that the cylindrical wall and the peripheral wall overlap at least partially for the locking of the first sub-assembly on the second sub-assembly.

According to another variant, the fixing member is carried by the second sub-assembly and the fixing element is carried by the first sub-assembly.

According to an alternative or complementary variant, a screw is introduced transversely to a portion of the flange forming a stop at an end portion of the peripheral wall of the protective housing and passes through said portions. Thus the cylindrical wall and the flange form part of an intermediate piece made integral in rotation with the motor rotor.

According to another alternative or complementary variant, a deformable retention piece is used to fix the end portion of the flange and the end portion of the peripheral wall of the protective housing together. The deformable retention part is configured to be deformed so as to engage and join the end portion of the flange and the end portion of the peripheral wall of the protective housing together. The invention also relates to a motor vehicle comprising a device for protecting an optical sensor / transmitter of a driving assistance system, as described above.

Other characteristics and advantages of the invention will appear more clearly on reading the following description, given by way of illustrative and nonlimiting example, and of the appended drawings among which:

- Figure 1 shows a front view of a motor vehicle, comprising at its grille, a driving assistance system according to the prior art;

- Figure 2 shows schematically and in perspective, a view of a device for protecting an optical sensor / transmitter of a driving assistance system according to the invention, a housing forming part of the device protection being made transparent to make visible the optical sensor / transmitter that it allows to be housed;

- Figure 3 shows in section the protection device illustrated in Figure 2, without the optical sensor / transmitter capable of being housed in the device;

- Figure 3bis is a detail of Figure 3, making more particularly visible the reversible holding means fitted to the protection device according to the invention;

- Figure 4 shows an exploded sectional view of the protection device of Figure 3, wherein the protective housing part and a motorized drive part are spaced from each other to facilitate viewing;

- Figure 5 shows in perspective the motorized drive part illustrated in Figure 4; and

- Figure 6 shows an alternative embodiment of a protection device according to the invention, in which the optical sensor / transmitter on the one hand and the motor configured to allow the driving of the protection device arranged around this sensor / optical transmitter on the other hand are represented this time. In these figures, identical elements have the same references.

The different realizations are examples. Although the description refers to one or more embodiments, this does not necessarily mean that each reference relates to the same embodiment, or that the characteristics apply to a single embodiment. Simple features of different embodiments can also be combined or interchanged to provide other embodiments.

Furthermore, it should be noted that in the description, it is possible to index certain elements, with for example a first element or a second element. In this case, it is a simple indexing to differentiate and name similar, but not identical, elements. This indexing does not imply a priority of one element over another and one can easily interchange such names without departing from the scope of this description. This indexing does not imply an order in time either.

A vehicle 100 is equipped according to the invention with a driving assistance system 1, which comprises at least one optical sensor / transmitter 2 and a protection device 4 arranged around this optical sensor / transmitter. In the example illustrated, it has been more particularly made visible an optical sensor / transmitter 2 formed by a front vision camera disposed in the grille 5 of the vehicle, but it will be understood that what follows in relation to such a sensor / transmitter optics can be implemented for devices also or alternately arranged at the rear or laterally with respect to the vehicle. According to the invention, at least the protection device 4 associated with the optical sensor / transmitter 2 is configured to prevent or limit the occurrence of condensation on the optical surfaces of the protection device and / or the optical sensor / transmitter.

The optical sensor / transmitter 2 is for example an optical sensor for taking pictures such as a camera. It can be a CCD sensor (for “charged coupled device” in English, namely a charge transfer device) or a CMOS sensor comprising a matrix of miniature photodiodes.

According to another variant, without this list being exhaustive, it may be an infrared radiation sensor such as an infrared camera, a light emitter such as a headlight, an optoelectronic device such as a light-emitting diode (LED), an electromagnetic radiation sensor / emitter such as a Lidar ("Laser, Imaging, Detection And Ranging") or as a Radar ("Radio, Detection And Ranging").

In FIG. 2, the protection device has been shown partially transparent to make the optical sensor / transmitter housed in the protection device visible. The optical sensor / transmitter 2 has an optical surface 6 and an optical axis 7. The optical surface 6 is for example a camera lens, which can include one or more lenses depending on the field of vision and the desired resolution.

In order to protect the optical sensor / transmitter 2 from possible splashing of dirt, it is arranged in the protection device 4, comprising a first sub-assembly B and a second sub-assembly C as illustrated in FIGS. 2 to 4.

The first subset B is configured to house at least the part of the optical sensor / transmitter used for the transmission and / or acquisition of images or data. More particularly, the first sub-assembly B comprises a protective casing 8 capable of rotating around this part of the optical sensor / transmitter.

The protective housing 8 has a peripheral wall 9 and a transverse wall 10 disposed perpendicular to the peripheral wall 9 at a first axial end 91 of the latter. These walls participate in delimiting a cavity 11 in which the optical sensor is housed, the optical sensor / transmitter being able to be inserted into the cavity 11 through the opening at the second axial end 92 open. The peripheral wall 9 and the transverse wall 10 are preferably centered around the optical axis 7 of the optical sensor / transmitter 2. In the example illustrated, the peripheral wall 9 is of substantially cylindrical shape.

The protective housing 8 also comprises an optical element 12 formed by a transparent wall and disposed downstream of the optical surface 6 of the optical sensor / transmitter 2. The optical element 12 is arranged on all or part of the transverse wall 10 and this the optical element 12 is advantageously dimensioned so as to cover the entire optical surface 6. In other words, the optical element 12 is arranged in the field of vision / emission of the optical sensor / transmitter 2, the transparent wall making it possible not to affect the efficiency of the optical sensor / transmitter 2. The optical element 12 can be made in one piece with the protective housing 8. Alternatively, the protective housing 8 and the optical element 12 can be two pieces distinct joined together. The transparent wall forming all or part of the optical element 12 can be made of glass or a plastic material such as poly carbonate. The protective housing 8 can be made of any suitable material known to those skilled in the art, preferably from a waterproof material.

By arrangement of the optical element 12 downstream of the optical surface 6, it is understood that the optical element 12 is disposed between the exterior of the vehicle and the optical surface 6 of the optical sensor / transmitter 2, so that the element optical 12 protects the optical surface 6 from possible projections of solid dirt or debris which could damage this optical surface 6. It is therefore a protective element, or more precisely a protective mask for the optical sensor / transmitter 2 , and it is this optical element 12 which is subjected to attacks from the outside, that is to say both water splashes, pollutants, gravel as pollutant deposits or traces of water.

In order to allow the cleaning of the surface of the optical element 12 by centrifugal effect, as described above, the protection device 4 comprises a motor 14 forming a second sub-assembly C. The motor 14 is coupled to the first sub-assembly assembly B, and more particularly to the protective housing 8, so as to rotate the protective housing 8 and therefore the optical element 12 around an axis of rotation A1, coincident with the optical axis 7 of the sensor / transmitter optics 2.

The motor 14 forming the second sub-assembly C is rotatably mounted around an axis of rotation A2 coincident with the axis of rotation Al of the first sub-assembly B, and with the optical axis 7 of the optical sensor / transmitter 2.

The motor 14 comprises a casing, a bottom wall and a peripheral wall of which form a housing inside which are arranged a rotor 22 and a stator 24. The stator 24 is here fixed on an internal face of the peripheral wall of this casing , the rotor 22 being movable in rotation relative to the fixed stator 24.

In the illustrated embodiment, the motor is an internal rotor motor, the rotor 22 rotating inside the stator 24. It will be understood that it may be envisaged that, without departing from the context of the invention, the motor comprises an external rotor.

The protective housing 8 and the associated optical element 12 are integral with the rotor 22 of the motor 14. In the example illustrated, an intermediate connecting piece 26 is disposed between the rotor 22 and the protective housing 8, being integral with each of its longitudinal ends of one and the other of these components. The rotational drive of the rotor 22 via the power supply of the stator 24 allows the intermediate connecting piece 26 to rotate, which rotates the protective housing 8 and the optical element 12 to be cleaned by centrifugal force if applicable.

The motor 14 comprises at least one magnet 28 integral with the rotor 22, and a predefined number of electromagnetic coils 30 mounted on the stator 24 and supplied with current to generate a magnetic field in which this at least one magnet 28 is capable of moving. It should be understood that the motor 14 comprises a control circuit configured to drive and supply the electromagnetic coils 30 and an associated electrical supply harness, not shown here. In the illustrated embodiment, and as more particularly visible in FIG. 6, the rotor 22 is arranged around a support element 32 secured to the optical sensor / transmitter 2 and forming a sheath for a bundle of electrical connection cables and video. The protection device 4, and more particularly at the level of the second sub-assembly C, comprises two bearings 34, 36 to ensure appropriate pivoting of a movable part of the protection device, formed in particular by the rotor 22 of the motor, the housing protection 8 and the optical element 12, relative to a fixed part of the protection device 4, formed in particular by the stator 24 of the motor. More particularly, with reference to the example illustrated in FIG. 6, the two bearings are arranged one between the support element 32 secured to the optical sensor / transmitter and the intermediate part 26 and the other between this same support element 32 integral with the optical sensor / transmitter and the rotor 22. It is understood that this arrangement is only a nonlimiting example and that the number and the position of the bearings could vary as soon as this allows the rotation of the movable part relative to the fixed part of the protection device.

According to the invention, and as is more particularly visible in FIGS. 3 to 4, the protective housing 8 and the rotor 22, here via the intermediate piece 26 secured to the rotor 22, are linked together by reversible holding means 40 . The reversible holding means 40 comprise at least a first thread 42 produced on the protective housing 8 and a second corresponding thread 44 produced on the intermediate piece 26, or on the rotor 22 in an embodiment where the rotor has a shape such that it is in direct relation with the protective box. More particularly, the first thread 42 forms a thread present on an internal face 90 of the peripheral wall 9 of the protective housing 8. The first thread 42 is produced with a screw pitch complementary to that of the second thread 44. The second thread 44 forms a bore on an external face of the intermediate part 26 integral in rotation with the rotor 22. The intermediate part 26 has a connection portion 46 with the rotor which is extended axially by a central junction portion 48, and this intermediate piece 26 comprises a flange 50 disposed at the end of this junction portion and which is extended substantially perpendicularly by a cylindrical wall 52 which extends opposite the second sub-assembly C. According to the invention, the second thread 44 is formed on the external face of the cylindrical wall 52.

The cylindrical wall 52 of the intermediate piece 26 is configured to be fitted into the protective housing 8 at the peripheral wall 9, so as to allow cooperation between the first and the second thread.

More particularly, the internal face of the peripheral wall 9 of the protective housing has a recess at its end so that a first end portion 54 and a second portion can be seen from the edge of the second axial end 92 end 56 of different diameters, the first end portion having a first internal diameter of greater value than the second internal diameter of the second end portion. It is understood that the internal diameters are measured in a direction radial to the axis of rotation of the protective housing.

As illustrated in FIGS. 3 to 4, the first thread 42 is produced on this second end portion of smaller internal diameter. In this way, the first thread 42 is distant from the second axial end 92 of the peripheral wall 9 of the protective housing. By way of example, the first thread 42 and the second axial end 92 are spaced apart by a distance, measured along the axis of rotation Al of the housing, between

5 mm and 25 mm.

The shoulder 58 thus formed between the two end portions advantageously allows a larger internal space to be provided at the end of the protective casing 8, in order to allow easier insertion of the protective casing around the cylindrical wall 52 of the intermediate piece 26, so as to limit the risks of impact and friction between the second thread 44 and the internal face of the peripheral wall 9 of the housing. This limits the risk of early wear of these elements. It should be noted that as is more visible in FIG. 3a, the shoulder has an inclined plane. In order to facilitate insertion guidance, it can be noted in the figures that the edge of the second axial end 92 of the peripheral wall 9 is chamfered on its internal edge.

Correspondingly, the cylindrical wall 52 of the intermediate piece 26 has a first zone 60 and a second zone 62 of different diameters, this time external. More particularly, the external diameter of the first zone is less than the external diameter of the second zone, the second thread 44 being produced on the first zone 60. And a second shoulder 64 is formed between the two zones of the cylindrical wall. The second shoulder 64 has an inclined plane of inclination substantially similar to that of the shoulder 58 formed on the protective housing 8. It is understood that the complementary shape of the shoulders 58, 64 allows the protective housing 8 to be fitted precisely on the intermediate part 26 in order to ensure unconstrained cooperation of the threads between them.

In this way, it is notable that the reversible holding means comprise a device for radial centering of the first sub-assembly relative to the second sub-assembly, which makes it possible to ensure that the radial dimension D illustrated in FIG. 3 is well centered on the Al, Al axis.

FIG. 3a more particularly illustrates a configuration of the second zone 62 according to which two bearings 66, 68 are formed at different heights, that is to say with different external diameters, the two bearings being separated by a groove 70.

The gradual increase in thickness of the second zone allows progressive alignment of the protective casing on the cylindrical wall during its fitting on the intermediate piece, so that the first and the second thread are perfectly aligned when they are screwed and that stresses which can degrade the threads are thus avoided.

In order to provide a seal between the rotating protective housing 8 and the intermediate piece 26 integral with the rotor 22, the reversible holding means also include a sealing means. As illustrated by way of example, an O-ring 72, for example an elastomer, is placed in the groove 70 formed in the second zone 62 of the cylindrical wall. The thickness of the O-ring 72 and the depth of the groove 70 are chosen so that on the one hand the O-ring does not protrude too much from the cylindrical wall so as not to be driven longitudinally during the fitting of the protective housing 8 onto the intermediate piece, and so that on the other hand the O-ring protrudes enough to prevent the passage of a fluid between the rotating protective housing and the intermediate piece 26 once assembled.

The cylindrical wall 52 extends from the collar 50 to a smaller radial dimension than the dimension of the radial end of this collar. In this way, the face of the flange facing the cylindrical wall forms a mechanical abutment face 74 around the entire periphery of the intermediate piece 26.

As is more particularly visible in the detailed view in FIG. 3b, the mechanical abutment face 74 forms a stop surface against which the protective casing 8 may come into contact when it is screwed onto the intermediate piece 26 In other words, the mechanical stop face 74 forms a stop making it possible to stop the screwing of the protective housing 8 on the intermediate piece 26, when the sub-assemblies B, C reach a certain fitting depth. It is understood that in this way, the mechanical abutment face, and here the flange which carries it, form a device for axial positioning of the reversible holding means, in order to respect a theoretical longitudinal dimension L, illustrated in FIG. 3, between the optical element and a reference surface of the second sub-assembly C on which the protective housing is assembled using the reversible holding means.

Thus, according to the invention, the reversible holding means 40 are configured on the one hand to allow the screwing and unscrewing of the protective box when it is necessary to replace the optical element at the end of the protective box, and d on the other hand to allow a seal between the two components which are screwed together. And advantageously, in a context where the protective housing has at its free end an optical element disposed upstream of the optical sensor / transmitter housed in the protective housing, and therefore in a context where the position of the optical element relative to the optical surface of the optical sensor / transmitter must be as precise as possible, the reversible holding means are configured to allow radial centering, by adjusting the position of the two stages formed respectively on the internal face of the housing and the external face of the intermediate piece, and the axial centering, by the stop of the end of the protective housing against the flange of the intermediate piece.

According to the invention, the reversible holding means of the protection device comprise a securing system configured to prevent the protective box 8 from being able to unscrew from the second sub-assembly C when the protective box is rotated by the motor. 14. The securing system may consist of a particular configuration of the direction of rotation of the threads produced respectively on the protective housing and on an element of the second sub-assembly, here the cylindrical wall 52 of the intermediate piece 26. More particularly, ensures according to the invention that the motor 14 is configured to pivot the rotor 22 in the same direction of rotation as this direction of rotation of the threads. The securing system may consist of a latching means which is not shown here and which could in particular be arranged at the end of the peripheral wall 9 of the housing. protection 8 so as to cooperate with the external face of the cylindrical wall 52, between the sealing groove and the shoulder forming an abutment wall.

If necessary, the reversible holding means 40 can consist of the combination of these latching means with the orientation of the same direction of rotation of the threads and rotation of the motor.

The protective device 4 can advantageously include, in the embodiment which has just been described, means for absorbing moisture. The moisture absorption means are present here to prevent or at least limit condensation on the transparent wall forming the optical element 12 integral with this protective housing 8. It is understood that a cleaning system operating by effect centrifugal involves on the one hand difficulties in sealing the cavity in which the sensor / transmitter extends, both with respect to air and humidity, and on the other hand an increase in the temperature of the made the engine work and therefore a change in the pressure in the cavity housing this sensor / transmitter, thus amplifying the air circulation, and the humidity entry, inside the protective housing.

It is therefore advantageous to provide, even if they are not illustrated in FIGS. 2 to 5, means for absorbing moisture, whether they are arranged in the cavity 11, on the rotor 22 or on the sensor / optical transmitter 2. It may for example be advantageous for the moisture absorption means to remain static when the protective housing 8 is pivoted by the motor, so that the humidity absorption means do not participate in modifying the balance of the body mass.

FIG. 6 illustrates an alternative embodiment in which moisture absorption means 76 are arranged on the internal face 90 of the peripheral wall 9 of the protective housing 8. It is advantageous in this variant that the absorption means d humidity are integral with the protective housing in the context of the invention or this protective housing is mounted on the second sub-assembly C via means of reversible support. Thus, each time it is necessary to replace the optical element integral with the protective housing, the new protective housing installed on the second sub-assembly is equipped with unused moisture absorption means and therefore more effective. The moisture absorption means 76 may in particular consist of a specific absorbent material such as magnesium carbonate, and for example upsalite, or any other equivalent porous material.

In order to avoid the creation of an unbalance during the rotation of the protective housing, the absorption means are preferably arranged all around the optical sensor / transmitter, around the entire periphery of the internal face of the peripheral wall.

Figures 7-10 illustrate different variants of reversible holding means connecting the protective housing and the rotor together.

Figures 7, 7bis and 8 illustrate other alternative embodiments, the holding means 40 comprise at least one fixing member 42 'produced on the protective housing 8 and at least one corresponding fixing element 44' produced on the part intermediate 26 or on the rotor in an embodiment where the rotor has a shape such that it is in direct relation with the protective housing.

The fixing member 42 ’having the shape of a female member capable of receiving a male element 44’ of complementary shape. More particularly, the fixing member 42 ’of this alternative embodiment forms an annular groove present on an internal face 90 of the peripheral wall 9 of the protective housing. The fastener 42 ’is made with a shape complementary to that of the fastening element 44’.

The fixing element 44 ′ forms an annular protuberance on an external face of the intermediate piece 26 integral in rotation with the rotor 22. The intermediate piece 26 has a connection portion 46 with the rotor which is extended axially by a central junction portion 48 and this intermediate part comprises a flange 50 disposed at the end of this junction portion and which is extended substantially perpendicularly by a cylindrical wall 52 which extends opposite the second subset. According to this embodiment, the fixing element is formed on the external face of the cylindrical wall 52. It is however conceivable that the fixing member 42 'is carried on the internal face 90 of the peripheral wall 9 of the protective housing. and that the fixing element 44 ′ is carried on the external face of the intermediate piece 26 integral in rotation with the rotor 22, as shown in FIG. 7a. The fixing member of FIG. 7bis is a fixing stud 42 ”carried on the internal face 90 of the peripheral wall 9 of the protective housing and the fixing element corresponds to a housing 44” on the external face of the part. intermediate 26.

The cylindrical wall 52 of the intermediate piece 26 is configured to be fitted into the protective housing 8 at the peripheral wall 9, so as to allow cooperation between the fixing member and the fixing element and the holding by snap-fastening the protective housing onto the intermediate piece 26.

The other technical characteristics described in the first embodiment corresponding to Figures 1 - 6 are also valid and applicable in this second embodiment. According to another alternative embodiment shown in Figure 8, the fixing member forms a hook 42 ”'on the internal face 90 of the peripheral wall 9 of the protective housing. The hook 42 ”has a lateral opening and a reception zone offset from the lateral opening in the main direction of elongation. The fixing element is produced in the form of a fixing lug 44 ”'formed in radial projection from the cylindrical wall 52. The fixing lug is then arranged in such a way that it cooperates with the complementary fixing member taking the hook shape carried by the wall the peripheral wall 9 of the protective housing. The fixing lug 44 '”is capable, in a bayonet type assembly, of passing through the lateral opening of the hook to come into abutment against the uprights of the hook delimiting the reception area. Such cooperation between the fixing lug and the hook allows the protective housing to be held and locked on the intermediate piece 26.

It is of course conceivable that the fixing lug 44 "'is carried on the internal face 90 of the peripheral wall 9 of the protective housing and that the hook 42"' is carried on the external face of the intermediate part 26 secured in rotor rotation 22.

According to this other alternative embodiment, the reversible holding means 40 of the protection device comprise the securing system described in the first embodiment, configured to prevent the protection box from being able to be dismantled from the second sub-assembly C during the setting in rotation.

The other technical characteristics described for the first embodiment corresponding to Figures 1 - 6 are also valid and applicable in this other alternative embodiment.

It is of course understood that the fixing member of the variants described above can also be carried by the second sub-assembly and the fixing element is carried by the first sub-assembly.

In addition, the number of fasteners 42 ', 42 ”, 42”' and fastening element 44 ', 44 ”, 44”' associated with the variants below carried by the two subsets can be 1 , 2, 3 or more.

Cumulatively to the two variants described above, the securing system may include a latching device 43 such as those shown in FIG. 9 making it possible to ensure the rotation of the subassemblies one relative to the other when these are snapped either by form cooperation according to the first variant, or by bayonet mounting according to the second variant. FIG. 10 illustrates an alternative or complementary variant of the reversible holding means described above, a screw 80 can be inserted transversely to a portion of the collar 50 forming a stop at an end portion of the peripheral wall of the protective housing and pass through these portions. Thus the cylindrical wall and the flange 50 form part of an intermediate piece made integral in rotation with the rotor of the motor.

FIG. 11 illustrates another alternative or complementary variant of the preceding variants of reversible holding means, a deformable retention piece 81 is used to fix the end portion of the flange 50 and the end portion of the peripheral wall 9 of the protective case together. The deformable retention piece 81 is configured to be deformed so as to engage and join the end portion of the flange and the end portion of the peripheral wall of the protective housing together in a reversible manner.

The invention, as just described, achieves the goals it set for itself and allows, by simple means, to produce a protection device in which maintenance operations are facilitated, with here a protective housing arranged around the optical sensor / transmitter which is both rotating and which is not permanently fixed, for example welded, on the rotating part of the drive motor of the protective housing.

It should be noted that the protection device adapts to all types of sensors / transmitters, whether optical, electromagnetic or even ultrasonic.

It should be noted that the different variants described above of a protection device according to the invention can be combined together in order to form a new embodiment not described.

Claims

1. Protection device (4) of an optical sensor / transmitter (2) of a driving assistance system (1) for a motor vehicle (100), in which a first sub-assembly (B) comprises a housing protection (8) able to receive at least partially the optical sensor / transmitter (2), said protective housing comprising an optical element (12) disposed opposite the optical sensor / transmitter (2) and in which a second sub-assembly (C) comprises a motor (14) configured to rotate the first sub-assembly (B) around an axis of rotation (Al), characterized in that the first sub-assembly (B) and the second sub- assembly (C) are linked by means of reversible holding means (40).

2. Protection device (4) according to the preceding claim, characterized in that the reversible holding means (40) comprise a set of threads configured to cooperate with each other and allow the first sub-assembly (B) to be screwed in, comprising a first thread (42) on the second sub-assembly (C), comprising a second thread (44).

3. Protection device (4) according to the preceding claim, characterized in that the first thread (42) of the first sub-assembly (B) is produced on an internal face of a peripheral wall (9) of the protective housing ( 8), in the vicinity of an axial end opposite the optical element.

4. Protection device (4) according to claim 2 or 3, characterized in that the second thread (44) of the second sub-assembly (C) is produced on an external face of a cylindrical wall (52) projecting d 'A flange (50) extending the rotor (24) of the motor (14) opposite the latter.

5. Protection device (4) according to one of claims 2 to 4, characterized in that the reversible holding means comprise a securing system configured to prevent the protective housing (8) from unscrewing from the second sub-assembly (C) when the protective housing is rotated by the motor (14).

6. Protection device (4) according to the preceding claim, characterized in that the motor (14) and the threads (42, 44) are configured so that the motor rotates the first sub-assembly (B), in the same direction as the direction of screwing between the first sub-assembly (B) and the second sub-assembly (C).

7. Protection device (4) according to one of the preceding claims, characterized in that the reversible holding means (40) comprise at least one axial positioning device (50, 74) of the protective housing.

8. Protection device (4) according to one of the preceding claims, characterized in that the reversible holding means (40) comprise a radial centering device (58, 64) of the first sub-assembly (B) relative to the second subset (C).

9. Protection device (4) according to one of the preceding claims, characterized in that the reversible holding means (40) also comprise a sealing means (70, 72) arranged between the first sub-assembly (B) and the second subset (C).

10. Protection device (4) according to claims 8 and 9, characterized in that the radial centering device (58, 64) and / or the sealing means are located axially between the threads (42, 44) and a mechanical stop face (74) of said axial positioning arrangement.