Device for protecting the optical sensors of a vehicle

Abstract

The present invention relates to a device (3) for protecting an optical sensor (2), such as a camera, of a vehicle. The protective device (3) includes: a protective housing (4) configured to receive the optical sensor (2), the protective housing (4) being mounted to be movable about a rotation axis (I-I) and including an optical window (10) configured to be arranged in the field of view of the optical sensor (2); and an electric motor (6) coupled to the protective housing (4) to rotate the protective housing. The protective device (3) further includes an element for enhancing heat transfer, the element being configured to improve heat transfer of the protective housing (4).

Description

Technical Field

[0001] This invention relates to the field of driver assistance, and more particularly to driver assistance systems including at least one optical sensor that can be mounted on certain vehicles. More specifically, this invention relates to a device for protecting optical sensors (such as cameras) of a vehicle, and to an associated optical device configured to be mounted in a motor vehicle, particularly in an opening in the vehicle body. Background Technology

[0002] Driver assistance systems include, for example, parking assistance systems and lane departure detection systems that use optical sensors mounted on the exterior of the vehicle.

[0003] Optical sensors are highly susceptible to splashes of mineral or organic contaminants that may deposit on their surfaces. Therefore, it is essential to protect and clean optical sensors to ensure they are in proper working order, a need that is particularly critical in autonomous vehicles where information gathered by these sensors is used to control the vehicle.

[0004] One solution is to enclose the optical sensor (such as a camera in a driver assistance system) in a rotating protective housing, thus protecting it from the external environment. The protective housing is enclosed by a transparent optical window with lenses facing the optical sensor to allow image capture. The protective housing and the optical window are rotated by a motor at a speed sufficient to remove any dirt or water from the optical window through centrifugal effect.

[0005] However, it may be necessary to provide a system for de-icing the device, because water in the protective device (e.g., in the form of moisture) may freeze on the components of the device or in the radial working gap between the rotating protective housing and the body components, potentially causing the protective housing to become stuck.

[0006] Therefore, it is known to place the electric heating element outside the housing, for example, by fastening it to the grille close to the housing, because the heating element cannot be directly mounted on the housing, especially on the optical window, since the housing rotates. The heating element can be powered on demand, especially under extremely cold conditions, to ensure that any frozen rotating parts can rotate freely without obstruction. However, this arrangement is cumbersome, and system integration can prove complex in terms of the encapsulation of protective devices or the fastening of the heating element to the grille.

[0007] The heating element can also be arranged directly next to the optical sensor inside the housing. However, this arrangement is limited to the optical sensors of a given vehicle and is not universal.

[0008] Another known method involves heating the motor without running it to raise the temperature of the housing, thereby breaking up ice inside the motor and in the gap between the rotating housing and the grille. A sequence is used to test whether the motor is blocked by ice and to help break up the ice layer using small rotating impacts. This method is used to effectively raise the temperature of the outer surface of the housing, thus allowing the system to rotate correctly.

[0009] However, some frost or ice may remain on the optical window because the motor's heating can only propagate very slowly toward the optical window due to limited air circulation and the numerous components between the motor and the optical window. Additionally, if, for example, little or no ice does not prevent the housing from rotating, but the optical window is frosted or iced, thus obstructing good visibility, the presence of such ice or frost will not be detected. Although this method can be used to completely de-ice the housing (including the optical window), it is relatively time-consuming. Summary of the Invention

[0010] The present invention proposes to overcome at least part of the above-mentioned disadvantages, particularly by de-icing the surface of the optical window of the protective device.

[0011] Therefore, the present invention relates to a protective device for protecting optical sensors (such as cameras) of a vehicle, the protective device comprising: - A protective housing configured to receive an optical sensor, the housing being mounted to be movable about a rotation axis and including an optical window configured to be positioned within the field of view of the optical sensor, and - An electric motor, which is connected to the protective housing to drive the protective housing to rotate. The protective device is characterized by further including a heat transfer enhancement element configured to improve the thermal conductivity of the protective housing.

[0012] Therefore, during operation, any dirt or water droplets deposit on the optical window but not on the lens of the optical sensor. The optical window is cleaned through centrifugal force due to the rotation of the protective housing. The heat transfer enhancement element improves heat transfer within the protective housing through thermal conduction, and thus improves heat transfer from the motor to the optical window. This allows the area around the optical window and optical sensor to be de-iced in the event of frost or ice, which is efficient, fast, and prevents diagnostic errors.

[0013] The protective device may also have one or more of the features described below, either individually or in combination.

[0014] According to one example embodiment, the protective housing includes a housing enclosed by an optical window and having a tubular end opposite to the optical window, the tubular end being fixed to the rotor of a motor so as to be driven to rotate.

[0015] Heat transfer enhancement elements can be formed by making a protective shell with a thermally conductive material (such as aluminum or aluminum-based alloys or filled plastic) and / or by coating the shell with a thermally conductive material.

[0016] Thermally conductive materials, for example, have a thermal conductivity greater than 150 W / m Thermal conductivity of K.

[0017] The outer surface of the casing, made of thermally conductive material, can also be coated with thermal insulation material.

[0018] The heat transfer enhancement element can be formed by a thermally conductive adhesive inserted between the optical window and the housing.

[0019] The heat transfer enhancement element can be formed by at least one thermally conductive bridge connecting the housing and the optical window.

[0020] The heat transfer enhancement element can be formed by a transparent thermally conductive optical coating on all or part of the inner and / or outer surfaces of the optical window, or by forming the optical window with a transparent thermally conductive material.

[0021] The protection device may include a control unit configured to alternately rotate the protective housing to heat the motor for a heating time longer than the time required to release the rotational obstruction of the protective housing.

[0022] The protective device may include an optical control unit configured to perform an optical inspection via an optical sensor to determine whether ice or frost is present on the optical window.

[0023] The present invention also relates to an optical device configured for installation in a motor vehicle, particularly in an opening in the vehicle body, the optical device including an optical sensor, characterized in that the optical device further includes a protective device as described above, the optical sensor being housed in a protective housing of the protective device. Attached Figure Description

[0024] Other advantages and features will become apparent from the following description of specific, but by no means limiting, embodiments of the invention, along with the accompanying drawings, in which: [ Figure 1 ][ Figure 1 [ ] is a cross-sectional view of the optical device. Detailed Implementation

[0025] The following embodiments are examples. Although the specification relates to one or more embodiments, this does not necessarily mean that each reference relates to the same embodiment, or that these features are applicable only to a single embodiment. Various features of different embodiments may be combined or interchanged to provide other embodiments without departing from the scope of the invention as defined in the claims.

[0026] [ Figure 1 The image shows an optical device 1 for example, a driver assistance system for a vehicle, which is configured to be installed in a motor vehicle, particularly in an opening in the vehicle body, such as a grille or an opening formed in the rear of the vehicle or its side wall.

[0027] The optical device 1 includes an optical sensor 2 and a protective device 3 for protecting the optical sensor 2.

[0028] Optical sensor 2 is, for example, a camera. The camera is used to capture images of the road scene, and these images can then be transmitted via a rigid power and communication cable 9, known as a video cable, to an electronic board, for example, in a vehicle, which manages and processes the images.

[0029] The protective device 3 includes, on the one hand, a rotating protective housing 4 that houses the optical sensor 2, and on the other hand, a motorized housing 5 and an electric motor 6 housed in the motorized housing 5. The rotor 14 of the motor 6 is connected to the protective housing 4 to drive its rotation, as described in more detail below.

[0030] The rigid power and communication cable 9 of the optical sensor 2 passes through the motor housing 5 and is fastened to the central support rod 8 of the optical sensor 2. The motor housing 5 also houses the electronics board 7 and connectors for powering and controlling the motor 6.

[0031] The protective housing 4 includes a transparent optical window 10 and a housing 11 closed at one end by the optical window 10. Once the optical device 1 has been installed in the vehicle body, the housing can protrude from the vehicle body.

[0032] Optical window 10 is arranged to face the lens of optical sensor 2 within the field of view of optical sensor 2, allowing images to be captured through optical window 10. Optical window 10 can be flat or curved, for example, inscribed within a sphere. It is made of glass, for example.

[0033] The protective housing 4 (i.e., housing 11 and optical window 10) is movably mounted around the rotation axis II. The axis of symmetry of the optical window 10 can coincide with the rotation axis II.

[0034] In this configuration, the housing 11 is made of two parts, 11a and 11b, with the front part 11a on the same side as the optical window 10. After the optical sensor 2 is inserted into the rear part 11b, the two parts 11a and 11b can be assembled and fastened together, for example, by a threaded connection. For example, the optical window 10 is fastened to a circular groove in the front part 11a of the housing 11 by gluing.

[0035] The housing 11 (in this case, the rear portion 11b) has a tubular end 12 opposite to the optical window 10. A central support rod 8 passes through the tubular end 12, and the central support rod itself is traversed by the rigid cable 9 of the optical sensor 2. This tubular end 12 of the housing 11 is fixed to the rotor 14 of the motor 6 so that it can be driven to rotate by the motor.

[0036] The protective device 3 may also include one or more bearings 13, in this case two bearings, which are inserted between the tubular end 12 of the housing 11 and the central support rod 8 that houses the rigid cable 9 of the optical sensor 2, so that the protective housing 4 can rotate about the central support rod 8, which is fixed relative to the protective housing 4.

[0037] Therefore, during operation, any dirt or water droplets deposit on the optical window 10 rather than on the lens of the optical sensor 2. The optical window 10 is cleaned by centrifugal force due to the rotation of the protective housing 4.

[0038] The protective device 3 further includes a heat transfer enhancement element configured to enhance the thermal conductivity of the protective housing 4. The heat transfer enhancement element improves heat transfer within the protective housing 4 through thermal conduction, and thus improves heat transfer from the motor 6 to the optical window 10, thereby enabling efficient, rapid, and diagnostically accurate de-icing of the area surrounding the optical window 10 and the optical sensor 2 in the event of frost or ice.

[0039] The heat transfer enhancement element may include one or more of the embodiments detailed below.

[0040] The heat transfer enhancement element can be formed by making the shell 11 of the protective housing 4 (in this case, the front portion 11a and the rear portion 11b) of a thermally conductive material or by coating the shell 11 of the protective housing 4 with a thermally conductive material. If the thermal conductivity of the material is greater than 150 W / m... If K is a constant, then the material can be considered thermally conductive.

[0041] The thermally conductive material can be aluminum, which possesses both excellent thermal conductivity and good mechanical properties. It can be pure aluminum (99.99% purity): approximately 237 W / m. K or an aluminum-based alloy, which may have a low or equivalent thermal conductivity. More generally, the material of the thermally conductive coating can be metallic, such as copper or aluminum.

[0042] Thermally conductive materials can also be filled plastics, such as polymer composites, which can exhibit improved thermal conductivity due to the addition of conductive fillers (such as aluminum nanoparticles or graphene). Graphene is a two-dimensional material composed of a single layer of carbon atoms arranged in a hexagonal lattice. Graphene has very high thermal conductivity, approximately 3000 to 5000 W / m. K, which makes it more thermally conductive than most conventional materials. When added to polymers, graphene can form a three-dimensional conductive network, thereby promoting heat conduction through the composite material. This provides graphene-filled plastics with higher thermal conductivity, approaching that of aluminum.

[0043] In another example, the coating material is a thin layer of hexagonal boron nitride (hBN). Hexagonal boron nitride has high thermal conductivity and can be deposited in the form of a thin layer.

[0044] The housing 11 produced or coated in this way improves heat transfer from the motor 6 to the optical window 10 of the protective housing 4.

[0045] The outer surface of the housing 11 can also be made of a thermally conductive material, in which case the first portion 11a and the second portion 11b are coated with an insulating material. The insulating material can be polyurethane foam. According to another example, the coating comprises a thin layer of a reflective material or a material with low thermal conductivity (such as aluminum or ceramic). These layers reflect or absorb radiant heat rather than transfer it. This type of coating can be thin, for example, between 1 micrometer and 20 micrometers. This reduces heat loss to the vehicle body, which faces or is in contact with the outer surface of the housing 11 protecting the outer shell 4.

[0046] The heat transfer enhancement element can be formed by a thermally conductive adhesive 16 inserted between the optical window 10 and the housing 11. In this case, the adhesive 16 allows the optical window 10 to be securely fastened in a groove in the front portion 11a of the housing 11. The thermally conductive adhesive 16 is, for example, a synthetic epoxy resin containing metallic and inorganic fillers, having a concentration of approximately 1.5 W / m. K has a thermal conductivity of K. The thermally conductive adhesive 16 forms a thermal bridge between the optical window 10 and the housing 11 to facilitate heat transfer from the housing 11 to the optical window 10.

[0047] The heat transfer enhancement element may be formed by at least one thermal bridge 17 connecting the housing 11 (in this case, the front portion 11a) and the optical window 10. The thermal bridge 17 may be formed by connecting lugs, and the heat transfer enhancement element may include one or more lugs, or the thermal bridge may be formed by an annular element arranged around the periphery of the optical window 10.

[0048] Thermal bridge 17 can be made of material with a thermal conductivity of 0.5 watts / meter. Kelvin (W / m) K) and 5 watts / meter Kelvin (W / m) It can be made of silicone-based materials with thermal conductivity between K and 10 W / m, or it can be made of materials with higher thermal conductivity, up to about 10 W / m It is made of silver oxide or hexagonal boron nitride (hBN) of K.

[0049] As an alternative to or supplement to the thermally conductive adhesive 16, the thermally conductive bridge 17 forms a thermal bridge between the optical window 10 and the housing 11 in order to facilitate the transfer of heat from the housing 11 to the optical window 10.

[0050] The heat transfer enhancement element may be formed by a transparent thermally conductive optical coating on all or part of the inner and / or outer surfaces of the optical window 10.

[0051] The coating is made, for example, of indium tin oxide (ITO), which has the advantages of being transparent and thermally conductive. It is, for example, less than 1 µm thick. The thermal conductivity of indium tin oxide is typically in the range of 1 to 20 watts per meter-Kelvin (W / m²). The thermal conductivity is in the range of K), and higher than that of glass, which typically ranges from 0.8 to 1.5 W / m. Within the range of K. This improves the thermal conductivity of the optical window 10 made of glass (glass itself has poor thermal conductivity) and allows heat to be transferred towards the center of the optical window 10.

[0052] The transparent thermally conductive optical coating on all or part of the inner and / or outer surfaces of the optical window 10 can be a metallic film, such as silver or copper deposited in thin layers. These metallic films are typically transparent.

[0053] The coating can be a film based on nanomaterials. Nanomaterials (such as copper, zinc oxide, or carbon nanoparticles) can be incorporated into transparent polymers to form thin thermal films. These nanomaterials provide higher thermal conductivity than polymers alone, which improves heat transfer through the film.

[0054] The coating can be a composite film. Composite films can be created by incorporating thermally conductive nanoparticles (such as hexagonal boron nitride (hBN) or graphene) into transparent polymers. These composite films exhibit increased thermal conductivity while maintaining the optical transparency of the glass.

[0055] A heat transfer enhancement element can be formed by making the optical window 10 a transparent thermally conductive material (such as optical glass filled with conductive metal nanoparticles).

[0056] The protective device 3 may further include a control unit comprising one or more controllers, microcontrollers, processors, and memory. This control unit is configured, on the one hand, to control the rotation of the motor 6, and therefore to control the rotation of the protective housing 4, and on the other hand, to alternately rotate the protective housing 4 to heat the motor 6 without thereby causing the motor 6 to rotate, the heating time exceeding the time required to release the rotational obstruction of the protective housing 4. The control unit may be mounted on an electronic board 7 housed within the motorized housing 5.

[0057] To rotate the rotor 14 of the motor 6, the control module is configured, for example, to supply power to different phases of the motor 6 sequentially in a given order and at a given frequency, according to a main power sequence, by controlling relays between each phase and the power supply. This main control command generates a rotating magnetic field that enables the rotor 14 to rotate.

[0058] To de-ice the protective casing 4, for example, if the external temperature of the vehicle is below zero degrees Celsius, or if the rotor 14 is prevented from rotating, or at the driver's request, the control unit generates a secondary power supply sequence, for example, by generating a high-frequency alternating power supply, such as greater than or equal to 1 kHz, between two phases of the winding. Thus, alternating the power supply to each phase generates two alternating magnetic fields in opposite directions. These alternating magnetic fields tend to hold the permanent magnets associated with the rotor 14 in a fixed position, and the inertia of the rotor 14 prevents the components from rotating until the magnetic fields reverse. Current is passed between the high-frequency phases, and the switching mechanism thus dissipates heat from the associated electrical or electronic components, while the rotor 14 is not driven to rotate and is not at risk of damage due to the obstruction provided by the frost layer.

[0059] Alternating rotation is used to test whether the protection device 4 is rotating or blocked, and where applicable, maintaining the secondary control command for a sufficient time helps to break the ice between the vehicle body and the protection device 4.

[0060] In this case, the heating time is longer than the time required to release the obstruction of the protective device 4 after the ice breaks. The motor 6, and therefore the protective housing 4, is thus heated, which heats the optical window 10, and the heat transfer enhancement element facilitates heat transfer between the motor 6 and the optical window 10. The alternating rotation during the additional time simultaneously promotes the removal of ice or frost, which begins to soften on the surface of the optical window 10 due to centrifugal effect (in the form of blocks or as water droplets of melting frost).

[0061] According to another example of the secondary power supply sequence, the control unit generates a reduced frequency power supply to the winding relative to the range of power supply frequencies generated by the main control command.

[0062] The protective device 3 may further include an optical control unit, which includes one or more controllers or microcontrollers or processors and memory, and is configured to perform an optical check via the optical sensor 2 to determine whether there is ice or frost on the optical window 10 in order to start and / or stop the alternating rotation of the protective housing 4.

[0063] The optical control unit is, for example, the same unit used to control the motor 6. Once the optical control unit has detected that there is no ice or frost on the optical window 10, the control unit can stop the alternating rotation of the protective housing 4 and command the protective housing 4 to rotate only in one direction so as to remove any particles, dust or water droplets deposited on the optical window 10 by centrifugal effect.

[0064] According to another example embodiment, the optical control unit and the control unit are separate from each other and communicate with the vehicle's central processing unit. The image captured by the optical sensor 2 is sent by the optical control unit to the central processing unit, which can accordingly control the motor 6 via the control unit to heat the protective housing 4 if frost or ice is detected, or to command the protective housing 4 to rotate in only one direction to expel impurities if there is no frost or ice.

Claims

1. A protective device (3) for protecting an optical sensor (2) of a vehicle, such as a camera, said protective device (3) comprising: - A protective housing (4) configured to receive the optical sensor (2), the protective housing (4) being mounted to be movable about a rotation axis (II) and including an optical window (10) configured to be arranged in the field of view of the optical sensor (2), and - An electric motor (6), which is connected to the protective housing (4) to drive the protective housing to rotate. The protective device (3) is characterized in that it further includes a heat transfer enhancement element configured to improve the heat conduction of the protective housing (4).

2. The protection device (3) according to claim 1, characterized in that, The protective housing (4) includes a housing (11) which is closed by the optical window (10) and has a tubular end (12) opposite to the optical window (10), the tubular end (12) being fixed to the rotor (14) of the motor (6) so as to be driven to rotate.

3. The protection device (3) according to claim 2, characterized in that, The heat transfer enhancement element is formed by making the housing (11) of the protective shell (4) with a thermally conductive material, such as aluminum or an aluminum-based alloy or filled plastic, and / or by coating the housing (11) with a thermally conductive material.

4. The protection device (3) according to claim 3, characterized in that, The thermally conductive material has a strength greater than 150 W / m Thermal conductivity of K.

5. The protective device (3) according to claim 3 or 4, characterized in that, The outer surface of the housing (11), which is made of thermally conductive material, is coated with thermal insulation material.

6. The protective device (3) according to any one of claims 2 to 5, characterized in that, The heat transfer enhancement element is formed by a thermally conductive adhesive (16) inserted between the optical window (10) and the housing (11).

7. The protective device (3) according to any one of claims 2 to 6, characterized in that, The heat transfer enhancement element is formed by at least one thermally conductive bridge (17) connecting the housing (11) and the optical window (10).

8. The protective device (3) according to any one of the preceding claims, characterized in that, The heat transfer enhancement element is formed by a transparent thermally conductive optical coating on all or part of the inner and / or outer surfaces of the optical window (10), or by making the optical window (10) with a transparent thermally conductive material.

9. The protective device (3) according to any one of the preceding claims, characterized in that, The protection device includes a control unit configured to alternately rotate the protective housing (4) to heat the motor (6) for a heating time longer than the time required to remove the rotational obstruction of the protective housing (4).

10. The protective device (3) according to any one of the preceding claims, characterized in that, The protective device includes an optical control unit configured to perform an optical inspection via the optical sensor (2) to determine whether ice or frost is present on the optical window (10).

11. An optical device (1) configured to be installed in a motor vehicle, particularly in an opening in the vehicle body, the optical device (1) comprising an optical sensor (2), characterized in that, The optical device further includes a protective device (3) according to any one of the preceding claims, wherein the optical sensor (2) is housed in a protective housing (4) of the protective device (3).

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