EP4034312A1 - Device for cleaning a support member covered with a liquid - Google Patents
Device for cleaning a support member covered with a liquidInfo
- Publication number
- EP4034312A1 EP4034312A1 EP20775644.6A EP20775644A EP4034312A1 EP 4034312 A1 EP4034312 A1 EP 4034312A1 EP 20775644 A EP20775644 A EP 20775644A EP 4034312 A1 EP4034312 A1 EP 4034312A1
- Authority
- EP
- European Patent Office
- Prior art keywords
- support
- transducers
- liquid
- orientation
- wave
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Pending
Links
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- 239000000523 sample Substances 0.000 claims description 5
- XLOMVQKBTHCTTD-UHFFFAOYSA-N Zinc monoxide Chemical compound [Zn]=O XLOMVQKBTHCTTD-UHFFFAOYSA-N 0.000 claims description 4
- GQYHUHYESMUTHG-UHFFFAOYSA-N lithium niobate Chemical compound [Li+].[O-][Nb](=O)=O GQYHUHYESMUTHG-UHFFFAOYSA-N 0.000 claims description 3
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Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B60—VEHICLES IN GENERAL
- B60S—SERVICING, CLEANING, REPAIRING, SUPPORTING, LIFTING, OR MANOEUVRING OF VEHICLES, NOT OTHERWISE PROVIDED FOR
- B60S1/00—Cleaning of vehicles
- B60S1/02—Cleaning windscreens, windows or optical devices
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B06—GENERATING OR TRANSMITTING MECHANICAL VIBRATIONS IN GENERAL
- B06B—METHODS OR APPARATUS FOR GENERATING OR TRANSMITTING MECHANICAL VIBRATIONS OF INFRASONIC, SONIC, OR ULTRASONIC FREQUENCY, e.g. FOR PERFORMING MECHANICAL WORK IN GENERAL
- B06B1/00—Methods or apparatus for generating mechanical vibrations of infrasonic, sonic, or ultrasonic frequency
- B06B1/02—Methods or apparatus for generating mechanical vibrations of infrasonic, sonic, or ultrasonic frequency making use of electrical energy
- B06B1/06—Methods or apparatus for generating mechanical vibrations of infrasonic, sonic, or ultrasonic frequency making use of electrical energy operating with piezoelectric effect or with electrostriction
- B06B1/0607—Methods or apparatus for generating mechanical vibrations of infrasonic, sonic, or ultrasonic frequency making use of electrical energy operating with piezoelectric effect or with electrostriction using multiple elements
- B06B1/0622—Methods or apparatus for generating mechanical vibrations of infrasonic, sonic, or ultrasonic frequency making use of electrical energy operating with piezoelectric effect or with electrostriction using multiple elements on one surface
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B08—CLEANING
- B08B—CLEANING IN GENERAL; PREVENTION OF FOULING IN GENERAL
- B08B17/00—Methods preventing fouling
- B08B17/02—Preventing deposition of fouling or of dust
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B08—CLEANING
- B08B—CLEANING IN GENERAL; PREVENTION OF FOULING IN GENERAL
- B08B7/00—Cleaning by methods not provided for in a single other subclass or a single group in this subclass
- B08B7/02—Cleaning by methods not provided for in a single other subclass or a single group in this subclass by distortion, beating, or vibration of the surface to be cleaned
- B08B7/026—Using sound waves
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B08—CLEANING
- B08B—CLEANING IN GENERAL; PREVENTION OF FOULING IN GENERAL
- B08B7/00—Cleaning by methods not provided for in a single other subclass or a single group in this subclass
- B08B7/02—Cleaning by methods not provided for in a single other subclass or a single group in this subclass by distortion, beating, or vibration of the surface to be cleaned
- B08B7/026—Using sound waves
- B08B7/028—Using ultrasounds
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B60—VEHICLES IN GENERAL
- B60S—SERVICING, CLEANING, REPAIRING, SUPPORTING, LIFTING, OR MANOEUVRING OF VEHICLES, NOT OTHERWISE PROVIDED FOR
- B60S1/00—Cleaning of vehicles
- B60S1/02—Cleaning windscreens, windows or optical devices
- B60S1/56—Cleaning windscreens, windows or optical devices specially adapted for cleaning other parts or devices than front windows or windscreens
Definitions
- the present invention relates to a method for moving a liquid, in particular a drop, a puddle or a liquid film, on a support, in particular in motion, by means of an ultrasonic surface wave.
- EWOD Electro Wetting On Devices
- autonomous motor vehicles include a large number of sensors in order to determine the distances and speeds of other vehicles on the road.
- sensors for example lidars
- lidars are also subject to inclement weather and splashing mud and require frequent cleaning.
- a wiper is unsuitable for cleaning a small area of such a sensor.
- WO 2012/095643 A1 describes a method for removing raindrops from a windshield by ultrasonic spraying.
- the amplitude and frequency of vibration are chosen so that the raindrops falling on the windshield are vaporized as soon as they enter the zone of vibratory movement of the surface of the windshield.
- the powers necessary for the setting in vibration of a support are high, which limits their practical implementation, in particular for the development of stand-alone devices. It is also well known that vaporization requires energies greater than those necessary to move drops on a support.
- the invention aims to meet this need, and it achieves this by providing an electroacoustic device comprising:
- At least two wave transducers acoustically coupled with the support and each being configured to generate an ultrasonic surface wave propagating in the support, the directions of propagation of the ultrasonic surface waves generated by the transducers being different,
- control unit configured to control at least one of the transducers, from the estimation of the orientation of the external force, so that the acoustic force is applying to the liquid, produced by the interaction between the ultrasonic surface wave (s) and the liquid, is oriented in a predetermined direction.
- the invention facilitates the movement of the liquid on the medium, by combining the effect of external force and the effect of acoustic force.
- external force is meant any force different from the acoustic force.
- external force are the weight of the liquid or an aerodynamic force induced by the flow of a fluid over the liquid.
- Those skilled in the art easily know how to determine the orientation of the acoustic force applied to a liquid placed on a support, and which is induced by a surface wave generated by a transducer.
- the acoustic force is oriented along the wave vector associated with the plane wave.
- the liquid is moved to the focal point of the transducer.
- the phenomena at the origin of the displacement of the liquid can be nonlinear.
- the acoustic force can therefore be substantially proportional to the intensity of the radiated acoustic wave and to the electrical intensity supplied to the transducer.
- the control unit may in particular include:
- a storage module for example a flash memory in which are recorded, for example in the form of a table, said set of orientations of the acoustic forces and the associated characteristics of the electric currents controlling the transducers, and
- a synthesis module configured to compare the estimated orientation of the external force with all the orientations of the acoustic forces recorded in the module and to supply the transducers with the associated electric control currents.
- control unit is configured to control the transducer (s) so as to minimize the angle between the orientation of the acoustic force projected onto the support and the estimated orientation of the external force projected onto the support, in order to to facilitate the movement of the liquid on the support.
- the evacuation of the liquid from the face of the support is thus accelerated.
- the control unit can be configured to choose transducers that generate an ultrasonic surface wave oriented in a direction close to the external force projected onto the media.
- Near direction is meant that the angle between the direction of the external force and the direction of propagation of the wave is less than 90 °, or even less than 45 °.
- the control unit can be configured to control each of the transducers thus chosen, so that the acoustic energy of the wave generated by the corresponding transducer is proportional to the angle between the external force projected on the support and the direction wave propagation.
- control unit is configured to control the transducer (s) so that the orientation of the acoustic force projected onto the support is substantially parallel to the orientation of the external force projected onto the support.
- the control unit may include a plurality of switches each configured to electrically open or close an electrical circuit for supplying a corresponding transducer.
- the control unit may include an electrical amplification member configured to amplify an electrical current supplied to one of the transducers.
- the control unit can be configured so that at least two of the transducers generate surface ultrasonic waves of different amplitudes.
- the fundamental frequency of the ultrasonic surface wave generated by at least one of the transducers, or even by each of the transducers is preferably between 0.1 MHz and 1000 MHz, preferably between 10 MHz and 100 MHz, for example equal to 40 MHz.
- the amplitude of the surface ultrasonic wave generated by at least one of the transducers, or even by each of the transducers, can be between 1 picometer and 500 nanometers. It can in particular depend on the fundamental frequency of the wave. It corresponds to the normal displacement of the face of the support on which the ultrasonic surface wave propagates and can be measured by laser interferometry.
- the ultrasonic surface wave can be a Rayleigh wave or a Lamb wave.
- it can be a Rayleigh wave when the medium has a thickness greater than the wavelength of the ultrasonic surface wave.
- a Rayleigh wave is preferred because the energy of the wave is concentrated on the face of the medium on which it propagates, and can thus be transmitted efficiently to the liquid.
- the analysis unit is configured to estimate, when a liquid is placed on the holder, the orientation of the external force applied to the liquid.
- the device comprises a measurement unit connected to the analysis unit and configured to measure at least one physical quantity. It is configured to receive the physical quantity, in particular with a frequency greater than 1 Hz, or even greater than 10 Hz, for example equal to 50 Hz.
- the physical quantity can characterize the support.
- the physical quantity can be chosen from the speed of the support with respect to a frame of reference and the position and / or orientation of the support in a frame of reference.
- the physical quantity is the speed of a motor vehicle comprising the electroacoustic device.
- the repository can be an absolute repository.
- An “absolute frame of reference” designates a geodetic frame of reference in which the location of an object on earth can be defined unambiguously.
- the absolute reference can be chosen from the following: French Geodetic Network 1993 (RGF93), World Geodetic System (WGS84), International Terrestrial Rotational Service (ITRS) or European Terrestrial Reference System (ETRS).
- the measurement unit can be connected to the analysis unit by means of an electric cable.
- the connection between the measurement unit and the analysis unit can be made by an electromagnetic wave link.
- the electroacoustic device may include the unit of measurement.
- the measurement unit can be remote from the device.
- the support is a surface of a motor vehicle and the measuring unit is disposed in the gearbox and is configured to convert the speed of the motor shaft to the speed of the vehicle, or is disposed in a wheel of the vehicle and is configured to measure the rotational speed of the wheel and convert it to the speed of the vehicle.
- the measurement unit can be a GPS transmitter / receiver configured to measure the position and / or orientation of the media.
- the physical quantity can characterize the liquid. For example, it can be the area of the liquid covering the support or the thickness of the liquid.
- the physical quantity can be the speed of a fluid, for example air, flowing around the medium.
- a measurement unit capable of measuring the speed of the fluid is, for example, a Pito probe or an MEMs sensor which can be mounted on the support.
- the device comprises a plurality of measurement units as described above.
- the device may include a communication module configured to communicate with a remote data server and to receive meteorological information from the data server, for example. the mean speed and / or the mean orientation of the wind, relative to the position and / or the orientation of the support.
- the communication module may in particular include a means of telecommunication, in particular cellular, for communicating with the data server.
- the analysis unit is configured to estimate the orientation of the external force by means of a digital estimation model taking as input data the physical quantity, the orientation of the support with respect to the horizontal and optionally the meteorological information provided by the communication module.
- the communication module can be configured to communicate with at least one other remote device which is provided with an analysis unit configured to estimate the orientation of the external force applied to the liquid, the communication module being further configured to receive the estimate of the orientation of the external force from the analysis unit of the other device.
- the device and the other device may be more than 1 m apart, or even more than 5 m and / or less than 1 km, or even less than 100 m.
- the device is mounted on a motor vehicle and the other device is mounted on another motor vehicle.
- Vehicles can follow the same path and the device mounted on the vehicle upstream in the path can transmit the estimate of the external force to the device mounted on the vehicle downstream.
- a person skilled in the art knows how to develop such an estimation model. For example, in a variant where the support is carried by a vehicle or is a surface of a vehicle, those skilled in the art can determine the air flow paths in different zones of the envelope of a vehicle. moving at a determined speed, based on an aerodynamic test in a wind tunnel. It can further determine the local velocity of the air flow in each of said zones, and thereby calculate an estimate of the force applied to the liquid in each of the zones.
- the analysis unit can estimate the orientation of the external force applied to a liquid, for example raindrops, on the external face of a support such as a windshield or a protective member.
- a sensor of a vehicle from the measurement of the speed of the vehicle, the orientation of the vehicle transmitted by a GPS transmitter / receiver, and the average speed and the average direction of the wind obtained from the server of data.
- the displacement of the liquid induced by the ultrasonic surface wave can in particular result from an acoustic streaming effect and / or from a radiation pressure effect induced by the ultrasonic surface wave (s).
- the liquid can be in the form of at least one drop, or in the form of a plurality of drops which may be of different sizes.
- the liquid can be in the form of at least one film, continuous or discontinuous.
- film is meant a thin film formed on the support.
- the liquid may be in the form of a puddle.
- the liquid can be aqueous.
- it can be rainwater or dew water.
- Rainwater and / or dew water may in particular contain fatty particles.
- Dew water forms a mist on the surface of a support. It results from the condensation on the support, under appropriate pressure and temperature conditions, of water in vapor form contained in the air.
- the device may include a detection unit configured to detect the presence of the liquid on the support.
- the detection unit can be configured to process a stream of images acquired by a camera and to detect when the camera is blinded by liquid.
- the sensing unit can be configured to process a flow of information from a LiDAR to detect the liquid-induced reduction in LiDAR range.
- the detection unit can be configured to measure and analyze a surface wave emitted by at least one of the transducers, in order to detect the presence of the liquid in contact with the support.
- the detection unit can be configured to measure the wave transmitted between two of the transducers arranged opposite each other on the support.
- the device can be configured so that one of the transducers generates an ultrasonic wave in the form of a pulse, for example a pulse or a Dirac, and to measure whether a response wave is produced by interaction between the liquid and the impulse, if the liquid is in contact with the support.
- surface wave transducers can themselves be used to detect the presence of liquid on the support, either by measuring the signal transmission between two transducers located opposite each other, or by sending pulses and measuring the echo generated by the reflection of the wave by the liquid.
- the support can be made of any material capable of propagating an ultrasonic surface wave. Preferably, it is made of a material for which the absorption length of the ultrasonic surface wave in the material is at least more than 10 times, or even at least more than 100 times greater than the surface of the support.
- the face of the medium on which the longitudinal surface wave propagates may be planar. It can also be curved, provided that the radius of curvature of the face is greater than the wavelength of the ultrasonic surface wave.
- the face may be rough. It may have roughness Ra less than the wavelength.
- the support may in particular be in the form of a flat plate, or having at least one curvature in one direction.
- the thickness of the plate can be less than 10 cm, or even less than 1 cm, or even less than 1 mm.
- the length of the plate may be greater than 1 cm, or even greater than 10 m, or even greater than 1 m.
- thickness of the support we consider the smallest dimension of the support measured in a direction perpendicular to the surface on which the ultrasonic wave propagates.
- the support can be laid out flat with respect to the horizontal. As a variant, it may be inclined relative to the horizontal by an angle a greater than 10 °, or even greater than 20 °, or even greater than 45 °, or even greater than 70 °. It can be arranged vertically.
- the support can be optically transparent, in particular to light in the visible.
- the method is thus particularly suitable for applications in which the improvement of the visual comfort of a user observing his environment through the medium is sought.
- the support can be made of a material chosen from piezoelectric materials, polymers, in particular thermoplastics, in particular polycarbonate, glasses, metals and ceramics.
- the support is made of a material other than a piezoelectric material.
- the support is chosen from the group formed by:
- an automotive surface for example chosen from a windshield of a vehicle, a glazing of a rear-view mirror, or
- an optical device for example chosen from a lens of a camera, a glass of a telescope, and a sensor, in particular a probe, for example a Pitot probe, or a lidar, and
- the support can be an element of the structure of an aircraft, for example a wing, a fuselage or an empennage.
- the device has at least two transducers.
- the device preferably comprises at least three, even at least four, better still at least eight wave transducers, preferably distributed regularly around an axis normal to one face. support.
- the device comprises at least two, or even at least three, better still at least four pairs of transducers, the transducers of the same pair being arranged so as to generate ultrasonic surface waves propagating in the same direction but in different directions. different meanings.
- the transducers of the same pair are arranged facing each other according to the direction of propagation of the waves that they can generate.
- the device may include an even number of transducers.
- the transducers can be fixed, and preferably glued, to the support. In particular, they can be arranged on an edge of the support.
- the transducers can at least partially cover the support, in particular the face of the support on which the liquid rests.
- At least one of the transducers, or even each of the transducers can directly generate the ultrasonic surface wave.
- at least one of the transducers, or even each of the transducers can generate an ultrasonic guided wave, which propagates at the interface between the medium and the transducer, and then transforms into the ultrasonic surface wave along it. a portion of the support disposed at a distance from said transducer.
- At least one of the transducers, or even each transducer may be in direct contact with the support or with an intermediate layer, for example formed of adhesive, disposed on the support.
- each transducer comprises first and second electrodes respectively forming first and second combs, the first and second combs being interdigitated and being arranged on the support and / or placed in direct contact with the support and / or in contact with an intermediate substrate in contact with, in particular placed on, the support, the substrate being made of a piezoelectric material.
- the piezoelectric material can be selected from the group consisting of lithium niobate, aluminum nitride, lead titanozircanate, zinc oxide, and mixtures thereof.
- the piezoelectric material can be opaque to light in the visible.
- the support is formed from the piezoelectric material and at least one of the transducers includes the support.
- the first and second combs are then preferably placed in contact with the support.
- the support is made of a material other than a piezoelectric material and the electrodes are arranged on the intermediate substrate.
- the first and second electrodes can be deposited by photolithography on the support and / or on the substrate.
- the first and second electrodes can be sandwiched between the support and the substrate, which preferably has a thickness at least once or even at least twice as much as the fundamental wavelength of the ultrasonic guided wave.
- the substrate can be sandwiched between the support and the first and second electrodes, and preferably has a thickness less than the fundamental wavelength of the ultrasonic guided wave.
- the first and second combs may preferably have a base from which extends a row of fingers, the fingers preferably being parallel to each other.
- the fingers may have a width of between one-eighth of the wavelength of the ultrasonic surface wave and half of said wavelength, preferably equal to one-quarter of said wavelength. The width of the fingers partly determines the fundamental frequency of the ultrasonic surface wave.
- the spacing between two consecutively adjacent fingers of a row of the first comb, respectively of the second comb may be between one eighth of the wavelength of the ultrasonic surface wave and half of said length d 'wave, preferably equal to a quarter of said wavelength.
- the row of fingers of the first comb and / or the row of fingers of the second comb may each comprise more than 2 fingers, or even more than 10 fingers, or even more. 40 fingers. Increasing the number of fingers increases the quality factor of the transducer.
- the substrate can be a thin film deposited, for example by chemical vapor deposition or by spraying on the support.
- the substrate can be self-supporting, that is, sufficiently rigid not to flex under the effect of its own weight.
- the self-supporting substrate can be fixed, for example glued, on the support.
- the portion of the liquid furthest from the transducer can be disposed at a distance several times the attenuation length of the surface wave in the holder.
- the device may include an electric generator, for example a battery, to supply each transducer electrically.
- the generator can be connected to the control unit. It can power the analysis unit.
- the electrical generator can deliver at least one of the transducers, or even each of the transducers, a power between 10 milliwatts and 50 watts.
- the invention also relates to a motor vehicle chosen from among a car, a bus, a motorcycle and a truck, the vehicle comprising a device according to the invention.
- the vehicle comprises a frame and the device is fixed relative to the frame.
- the invention also relates to a method comprising the provision of a device, in particular as according to the invention, comprising a support covered with a liquid and at least two wave transducers acoustically coupled with the support and each being configured to generate an ultrasonic surface wave propagating in the medium, the directions of propagation of the ultrasonic surface waves generated by the transducers being different, the method comprising estimating the orientation of the external force applied to the liquid, and by depending on said estimate, the power supply of at least one of the transducers to propagate one or more ultrasonic surface waves in the support so that the acoustic force applied to the liquid, produced by the interaction between the one or more ultrasonic surface waves and liquid, or oriented in a predetermined direction.
- the device is mounted on a motor vehicle and the estimation of the external force comprises the measurement of the speed of the vehicle.
- the invention finally relates to a motor vehicle comprising a vehicle speed sensor and an electroacoustic device, in particular according to the invention, comprising:
- At least two wave transducers acoustically coupled with the support and each being configured to generate an ultrasonic surface wave propagating in the support, the directions of propagation of the ultrasonic surface waves generated by the transducers being different, and
- control unit configured to control, by means of the speed of the vehicle, at least one of the transducers so that, when a liquid is placed on the support, the acoustic force applied to the liquid, produced by the interaction between the ultrasonic surface wave (s) and the liquid is oriented in a predetermined direction.
- Figure 1 shows, in a perspective view, a motor vehicle comprising an example of a device according to the invention
- FIG 2 is an enlargement of Figure 1 showing a portion of the device according to the invention
- FIG 3 is a schematic representation of the device of the example
- Figure 4 illustrates an example of a method for choosing the transducers to activate
- Figure 5 shows an embodiment of a transducer of an example device
- Figure 6 shows another embodiment of a transducer of an exemplary device.
- FIG. 1 represents a motor vehicle 5 which contains an example of a device 10 according to the invention.
- the device comprises a plurality of ultrasonic surface wave transducers 15a-h and a support 20, defined by a porthole mounted in a window 25 formed in a protective case 30 of a lidar, on which the transducers are arranged.
- the device further comprises an analysis unit 35 and a control unit 40 of the transducers, both housed in the vehicle.
- the window is transparent to visible light and is for example made of glass or polycarbonate.
- a lidar is housed in the protective housing and emits an L laser beam through the window, in order to detect obstacles 45, pedestrians and other vehicles located in the vicinity of the vehicle.
- the window is flat, but in a variant, it can be curved.
- transducers are arranged on the contour of the external face 50 of the window, exposed to the wind and to the rain. They are also arranged regularly around the axis X passing through the center C of the window and which is perpendicular to the face.
- transducers for example referenced 15 a and 15 e, arranged symmetrically relative to the center form pairs, each transducer of a pair of ultrasonic wave emitting surface, e.g. Wa, in an opposite direction to the direction of the wave, for example We, emitted by the transducer of the other pair.
- each transducer is configured to propagate an ultrasonic surface wave W ae oriented substantially towards the center C.
- at least one transducers of the device can be controlled to generate a surface wave capable of inducing an acoustic force whose component projected onto the support is oriented substantially parallel to the projected external force.
- transducers can be envisaged.
- the number of transducers is not limiting, and can be reduced or increased.
- the analysis unit is housed in the vehicle, for example under the front hood or in the passenger compartment. It is connected by means of electric cables 53 to a vehicle speed measuring unit 55 arranged in a wheel 60 of the vehicle and is configured to measure the rotational speed of the wheel and convert it into the speed of the vehicle.
- Unity analysis is further connected and to a GPS transmitter / receiver 65 which measures the position and orientation of the vehicle, and which can further estimate the speed of the vehicle.
- the analysis unit can receive the speed, orientation and position of the vehicle.
- the analysis unit is connected to a cellular communication module 70 to interrogate a remote weather data server and receive from the server the direction and speed of the wind, in the position of the vehicle.
- the analysis unit estimates the orientation of the external force using a digital estimation model taking as input the speed, vehicle position and orientation, and weather information.
- the estimation model also takes into account the position of the window relative to the horizontal to estimate the component related to the weight of the liquid.
- G analysis unit can estimate the orientation OF e of the external force and transmit it to the control unit 40.
- the control unit is electrically connected to the analysis unit and to a multi-channel current generator 75.
- Each 80a-h channel of the current generator is electrically connected to a corresponding 15a-h transducer to supply power to the transducer.
- the control unit further includes a plurality of switches 85ah, each electrically disposed between the current generator and the transducer.
- the control unit further comprises a synthesis module 90.
- the synthesis module chooses, from among all the transducers of the device, the transducers generating an ultrasonic surface wave having an angle ⁇ of less than 90 ° with the orientation of the device. the projected external force OF ep on the support. For example, in Figure 3, the transducers 15d, 15 e and 15f are selected because they have angles ot df less than 90 °.
- the control unit places the switches of the electrical circuits supplying the selected transducers in the open position and the other switches in the closed position. It then controls the current generator so that the intensity of the current transmitted to each of the selected transducers is proportional to the angle ⁇ .
- the acoustic force generated by the interaction between the acoustic waves of the selected transducers and the liquid, projected onto the OF ap support is substantially parallel and oriented in the same direction as the force external projection onto the support.
- the liquid is then subjected to a force of greater intensity than the only external force, which facilitates its detachment and its displacement on the support.
- Figure 5 illustrates an example of the arrangement of one of the transducers on the support of the example shown in Figure 1.
- the transducer comprises a substrate 100 on which are arranged first 105 and second 110 electrodes.
- the substrate is for example lithium niobate cut at 128 °.
- the electrodes are deposited by photolithography. They consist of a layer of bonding to the intermediate substrate formed of titanium and a thickness equal to 20 nm and a conductive layer of gold with a thickness of 100 nm.
- the first and second electrodes form first 115 and second 120 combs.
- Each comb has a base 125,130 and a row of fingers 135,140 extending parallel to each other from the base.
- the first and second combs are interdigitated.
- the spacing between the fingers determines the resonant frequency of the transducer which one skilled in the art can easily determine.
- the alternating electrical voltage of the first and second electrodes induces a mechanical response of the piezoelectric material disposed between two consecutive fingers of the first and second combs, which results in the generation of an ultrasonic surface wave W which propagates in the support according to a direction of propagation P, perpendicular to the fingers of the first and second combs.
- Figure 6 illustrates another arrangement of the transducers on the support.
- the transducer comprises a self-supporting substrate 100 and the first 105 and second 110 electrodes are deposited on the face of the substrate 50 bonded to the support 100.
- the transducer When an electric current passes through the first and second electrodes, the transducer generates an ultrasonic guided wave G, which propagates between the support and the substrate.
- the guided wave reaches the end 150 of the substrate along its direction of propagation, it is transformed into an ultrasonic surface wave W which propagates in the portion 160 of the support separated from the substrate, in substantially the same direction of propagation. than the guided wave.
- the transformation of the guided wave into a surface wave results from the absence of an interface between two solids in the portion of the support.
- the arrangement of the transducer illustrated in FIG. 6 has the advantage of protecting the first and second electrodes.
- the device illustrated in FIG. 4 can include a protection member 155 which defines with the support a housing for the transducer. This prevents objects which strike the device from damaging the transducer.
Landscapes
- Engineering & Computer Science (AREA)
- Mechanical Engineering (AREA)
- Measurement Of Velocity Or Position Using Acoustic Or Ultrasonic Waves (AREA)
- Investigating Or Analyzing Materials By The Use Of Ultrasonic Waves (AREA)
- Cleaning By Liquid Or Steam (AREA)
- Rear-View Mirror Devices That Are Mounted On The Exterior Of The Vehicle (AREA)
- Cleaning In General (AREA)
- Measurement Of Mechanical Vibrations Or Ultrasonic Waves (AREA)
Abstract
Device for cleaning a support member covered with a liquid
Electroacoustic device (10) comprising: - a support member (50), - at least two wave transducers (15a-h) which are acoustically coupled to the support member and each configured to generate an ultrasonic surface wave (Wa-h) which propagates in the support member, the propagation directions (P) of the ultrasonic surface waves generated by the transducers being different; - a control unit (40), the device comprising an analysis unit (35) which is configured to estimate the orientation of the external force (OFe) which is applied to a liquid when the liquid is in contact with the support member and/or the device being configured to receive the estimate of the orientation of the external force, the control unit being configured to control at least one of the transducers, from the estimate of the orientation of the external force, so that the acoustic force which is applied to the liquid and produced by the interaction between the ultrasonic surface wave(s) and the liquid is orientated in a predetermined direction.
Description
Description Description
Titre : Dispositif pour nettoyer un support recouvert d’un liquide Title: Device for cleaning a support coated with liquid
La présente invention concerne un procédé pour déplacer un liquide, notamment une goutte, une flaques ou un film liquide, sur un support, notamment en mouvement, au moyen d’une onde de surface ultrasonore. The present invention relates to a method for moving a liquid, in particular a drop, a puddle or a liquid film, on a support, in particular in motion, by means of an ultrasonic surface wave.
Dans des domaines variés, il est nécessaire de s’affranchir des effets liés à l’accumulation d’un liquide sur une surface. In various fields, it is necessary to overcome the effects of the accumulation of liquid on a surface.
Il est connu de mettre en rotation les gouttes d’un liquide pour les évacuer d’une surface. Cependant, une telle technique n’est pas adaptée à des surfaces dont l’aire est supérieure à quelques centimètres carrés. It is known to rotate the drops of a liquid to evacuate them from a surface. However, such a technique is not suitable for surfaces with an area of more than a few square centimeters.
La mise en œuvre d’un champ électrique pour contrôler l’hydrophobicité d’une surface est aussi connue, par exemple de KR 2018 0086173 Al. Cette technique, connue sous l’acronyme EWOD (pour « Electro Wetting On Devices » en anglais) consiste à appliquer une différence de potentiel entre deux électrodes, de sorte à polariser électriquement la surface pour la rendre hydrophile, déliant ainsi la goutte de la surface. En contrôlant la localisation de la polarisation, la goutte peut alors être déplacée. Cependant, cette technique ne peut être mise en œuvre qu’avec des matériaux particuliers et nécessite un positionnement particulièrement précis des électrodes sur toute la surface où l’on veut contrôler les propriétés de mouillage. The implementation of an electric field to control the hydrophobicity of a surface is also known, for example from KR 2018 0086173 Al. This technique, known by the acronym EWOD (for “Electro Wetting On Devices”) consists in applying a potential difference between two electrodes, so as to electrically polarize the surface to make it hydrophilic, thus unbinding the drop from the surface. By controlling the location of the polarization, the drop can then be moved. However, this technique can only be implemented with particular materials and requires particularly precise positioning of the electrodes over the entire surface where we want to control the wetting properties.
Il est aussi bien connu d’appliquer un effort mécanique sur le liquide, par exemple au moyen d’un essuie-glace sur un pare-brise d’un véhicule automobile. Toutefois, un essuie-glace limite le champ de vision accessible au conducteur. Il étale en outre les particules grasses déposées en surface du pare-brise. De plus, il est nécessaire de renouveler les garnitures de l’essuie-glace régulièrement. It is also well known to apply a mechanical force to the liquid, for example by means of a wiper on a windshield of a motor vehicle. However, a wiper limits the field of vision accessible to the driver. It also spreads the fatty particles deposited on the surface of the windshield. In addition, it is necessary to renew the wiper linings regularly.
Par ailleurs, les véhicules automobiles autonomes comportent un nombre élevé de capteurs afin de déterminer les distances et vitesses des autres véhicules présents sur la route. De tels capteurs, par exemple des lidars, sont eux aussi soumis aux intempéries et aux projections de boue et requièrent d’être nettoyés fréquemment. Cependant, un essuie-glace est inadapté au nettoyage d’une surface faiblement étendue d’un tel capteur. In addition, autonomous motor vehicles include a large number of sensors in order to determine the distances and speeds of other vehicles on the road. Such sensors, for example lidars, are also subject to inclement weather and splashing mud and require frequent cleaning. However, a wiper is unsuitable for cleaning a small area of such a sensor.
Des procédés pour évacuer un liquide s’accumulant sur un support sont connus, qui mettent en œuvre la génération et la propagation d’ondes de surface ultrasonores dans le
support. En particulier, WO 2012/095643 Al décrit un procédé pour évacuer les gouttes de pluie d’un pare-brise par vaporisation ultrasonique. Les amplitude et fréquence de vibration sont choisies de sorte que les gouttes de pluie tombant sur le pare-brise soient vaporisées dès qu’elles entrent dans la zone de mouvement vibratoire de la surface du pare-brise. Toutefois, afin d’obtenir une vaporisation d’une goutte de liquide, d’une flaque ou d’un film, les puissances nécessaires à la mise en vibration d’un support sont élevées, ce qui limite leur mise en œuvre pratique, notamment pour le développement de dispositifs autonomes. Il est d’ailleurs bien connu que la vaporisation nécessite des énergies supérieures à celles nécessaires pour déplacer des gouttes sur un support. Methods for removing liquid accumulating on a medium are known which involve the generation and propagation of ultrasonic surface waves in the medium. support. In particular, WO 2012/095643 A1 describes a method for removing raindrops from a windshield by ultrasonic spraying. The amplitude and frequency of vibration are chosen so that the raindrops falling on the windshield are vaporized as soon as they enter the zone of vibratory movement of the surface of the windshield. However, in order to obtain a vaporization of a drop of liquid, of a puddle or of a film, the powers necessary for the setting in vibration of a support are high, which limits their practical implementation, in particular for the development of stand-alone devices. It is also well known that vaporization requires energies greater than those necessary to move drops on a support.
Il existe toujours un besoin pour améliorer l’évacuation d’un liquide hors d’un support revêtu par le liquide. There is still a need to improve the removal of liquid from a medium coated with the liquid.
L’invention vise à satisfaire ce besoin, et elle y parvient en proposant un dispositif électroacoustique comportant : The invention aims to meet this need, and it achieves this by providing an electroacoustic device comprising:
- un support, - a support,
- au moins deux transducteurs d’onde couplés acoustiquement avec le support et étant configurés chacun pour générer une onde de surface ultrasonore se propageant dans le support, les directions de propagation des ondes de surface ultrasonores générées par les transducteurs étant différentes, - at least two wave transducers acoustically coupled with the support and each being configured to generate an ultrasonic surface wave propagating in the support, the directions of propagation of the ultrasonic surface waves generated by the transducers being different,
- une unité de contrôle, le dispositif comportant une unité d’analyse configurée pour estimer l’orientation de la force externe s’appliquant sur un liquide, lorsque le liquide est au contact du support et/ou le dispositif étant configuré pour recevoir l’estimation de l’orientation de la force externe, l’unité de contrôle étant configurée pour commander au moins l’un des transducteurs, à partir de l’estimation de l’orientation de la force externe, de manière que la force acoustique s’appliquant sur le liquide, produite par l’interaction entre la ou les ondes de surface ultrasonores et le liquide, soit orientée dans un sens prédéterminé. a control unit, the device comprising an analysis unit configured to estimate the orientation of the external force applied to a liquid, when the liquid is in contact with the support and / or the device being configured to receive the estimation of the orientation of the external force, the control unit being configured to control at least one of the transducers, from the estimation of the orientation of the external force, so that the acoustic force is applying to the liquid, produced by the interaction between the ultrasonic surface wave (s) and the liquid, is oriented in a predetermined direction.
L’invention facilite le déplacement du liquide sur le support, en combinant l’effet de la force externe et l’effet de la force acoustique. The invention facilitates the movement of the liquid on the medium, by combining the effect of external force and the effect of acoustic force.
Par « force externe », on entend toute force différente de la force acoustique. Le poids du liquide ou une force aérodynamique induite par l’écoulement d’un fluide sur le liquide sont des exemples de force externe.
L’homme du métier sait aisément déterminer l’orientation de la force acoustique s’appliquant sur un liquide disposé sur un support, et qui est induite par une onde de surface générée par un transducteur. Dans le cas d’une onde de surface plane, la force acoustique est orientée suivant le vecteur d’onde associée à l’onde plane. Dans le cas d’une onde de surface focalisée, le liquide est déplacé vers le point focal du transducteur. Les phénomènes à l’origine du déplacement du liquide peuvent être non linéaires. La force acoustique peut donc être sensiblement proportionnelle à l’intensité de l’onde acoustique rayonnée et à l’intensité électrique alimentant le transducteur. By "external force" is meant any force different from the acoustic force. Examples of external force are the weight of the liquid or an aerodynamic force induced by the flow of a fluid over the liquid. Those skilled in the art easily know how to determine the orientation of the acoustic force applied to a liquid placed on a support, and which is induced by a surface wave generated by a transducer. In the case of a plane surface wave, the acoustic force is oriented along the wave vector associated with the plane wave. In the case of a focused surface wave, the liquid is moved to the focal point of the transducer. The phenomena at the origin of the displacement of the liquid can be nonlinear. The acoustic force can therefore be substantially proportional to the intensity of the radiated acoustic wave and to the electrical intensity supplied to the transducer.
L’unité de contrôle peut notamment comprendre : The control unit may in particular include:
- un module de stockage, par exemple une mémoire flash dans laquelle sont enregistrées, par exemple sous la forme d’une table, ledit ensemble des orientations des forces acoustiques et les caractéristiques associées des courants électriques de commande des transducteurs, et- a storage module, for example a flash memory in which are recorded, for example in the form of a table, said set of orientations of the acoustic forces and the associated characteristics of the electric currents controlling the transducers, and
- un module de synthèse configuré pour comparer l’orientation estimée de la force externe avec l’ensemble des orientations des forces acoustiques enregistrées dans le module et pour alimenter les transducteurs avec les courants électriques de commande associés. - a synthesis module configured to compare the estimated orientation of the external force with all the orientations of the acoustic forces recorded in the module and to supply the transducers with the associated electric control currents.
De préférence, l’unité de contrôle est configurée pour commander le ou les transducteurs de manière à minimiser l’angle entre l’orientation de la force acoustique projetée sur le support et l’orientation estimée de la force externe projetée sur le support, afin de faciliter le déplacement du liquide sur le support. L’évacuation du liquide de la face du support est ainsi accélérée. Preferably, the control unit is configured to control the transducer (s) so as to minimize the angle between the orientation of the acoustic force projected onto the support and the estimated orientation of the external force projected onto the support, in order to to facilitate the movement of the liquid on the support. The evacuation of the liquid from the face of the support is thus accelerated.
L’unité de contrôle peut être configurée pour choisir les transducteurs générant une onde de surface ultrasonore orientée dans un sens proche de la force externe projetée sur le support. Par « sens proche », on entend que l’angle entre la direction de la force externe et le sens de propagation de l’onde est inférieure à 90°, voire inférieure à 45°. L’unité de contrôle peut être configurée pour commander chacun des transducteurs ainsi choisis, de telle sorte que l’énergie acoustique de l’onde générée par le transducteur correspondant soit proportionnelle à l’angle entre la force externe projetée sur le support et le sens de propagation de l’onde. The control unit can be configured to choose transducers that generate an ultrasonic surface wave oriented in a direction close to the external force projected onto the media. By "near direction" is meant that the angle between the direction of the external force and the direction of propagation of the wave is less than 90 °, or even less than 45 °. The control unit can be configured to control each of the transducers thus chosen, so that the acoustic energy of the wave generated by the corresponding transducer is proportional to the angle between the external force projected on the support and the direction wave propagation.
De préférence, l’unité de contrôle est configurée pour commander le ou les transducteurs de manière que l’orientation de la force acoustique projetée sur le support soit sensiblement parallèle à l’orientation de la force externe projetée sur le support.
L’unité de contrôle peut comporter une pluralité de commutateurs configurés chacun pour ouvrir ou fermer électriquement un circuit électrique d’alimentation d’un transducteur correspondant. Preferably, the control unit is configured to control the transducer (s) so that the orientation of the acoustic force projected onto the support is substantially parallel to the orientation of the external force projected onto the support. The control unit may include a plurality of switches each configured to electrically open or close an electrical circuit for supplying a corresponding transducer.
L’unité de contrôle peut comporter un organe d’amplification électrique configuré pour amplifier un courant électrique alimentant l’un des transducteurs. En particulier, l’unité de contrôle peut être configurée pour qu’au moins deux des transducteurs génèrent des ondes ultrasonores de surface d’amplitudes différentes. The control unit may include an electrical amplification member configured to amplify an electrical current supplied to one of the transducers. In particular, the control unit can be configured so that at least two of the transducers generate surface ultrasonic waves of different amplitudes.
Afin d’assurer un déplacement optimal du liquide sur la surface du support, la fréquence fondamentale de l’onde de surface ultrasonore générée par au moins l’un des transducteurs, voire par chacun des transducteurs, est de préférence comprise entre 0,1 MHz et 1000 MHz, de préférence comprise entre 10 MHz et 100 MHz, par exemple égale à 40 MHz. In order to ensure optimum movement of the liquid on the surface of the support, the fundamental frequency of the ultrasonic surface wave generated by at least one of the transducers, or even by each of the transducers, is preferably between 0.1 MHz and 1000 MHz, preferably between 10 MHz and 100 MHz, for example equal to 40 MHz.
L’amplitude de l’onde ultrasonore de surface générée par au moins l’un des transducteurs, voire par chacun des transducteurs, peut être comprise entre 1 picomètre et 500 nanomètres. Elle peut notamment dépendre de la fréquence fondamentale de l'onde. Elle correspond au déplacement normal de la face du support sur laquelle se propage l’onde de surface ultrasonore et peut être mesurée par interférométrie laser. The amplitude of the surface ultrasonic wave generated by at least one of the transducers, or even by each of the transducers, can be between 1 picometer and 500 nanometers. It can in particular depend on the fundamental frequency of the wave. It corresponds to the normal displacement of the face of the support on which the ultrasonic surface wave propagates and can be measured by laser interferometry.
L’onde de surface ultrasonore peut être une onde de Rayleigh ou une onde de Lamb. En particulier, elle peut être une onde de Rayleigh lorsque le support présente une épaisseur supérieure à la longueur d’onde de l’onde de surface ultrasonore. Une onde de Rayleigh est privilégiée car l’énergie de l’onde est concentrée sur la face du support sur laquelle elle se propage, et peut ainsi être transmise efficacement au liquide. The ultrasonic surface wave can be a Rayleigh wave or a Lamb wave. In particular, it can be a Rayleigh wave when the medium has a thickness greater than the wavelength of the ultrasonic surface wave. A Rayleigh wave is preferred because the energy of the wave is concentrated on the face of the medium on which it propagates, and can thus be transmitted efficiently to the liquid.
L’unité d’analyse est configurée pour estimer, lorsqu’un liquide est disposé sur le support, l’orientation de la force externe s’appliquant sur le liquide. The analysis unit is configured to estimate, when a liquid is placed on the holder, the orientation of the external force applied to the liquid.
De préférence, le dispositif comporte une unité de mesure connectée à l’unité d’analyse et configurée pour mesurer au moins une grandeur physique. Elle est configurée pour recevoir la grandeur physique, en particulier avec une fréquence supérieure à 1 Hz, voire supérieure à 10 Hz, par exemple égale à 50Hz. Preferably, the device comprises a measurement unit connected to the analysis unit and configured to measure at least one physical quantity. It is configured to receive the physical quantity, in particular with a frequency greater than 1 Hz, or even greater than 10 Hz, for example equal to 50 Hz.
La grandeur physique peut caractériser le support. Par exemple, la grandeur physique peut être choisie parmi la vitesse du support par rapport à un référentiel et la position et/ou l’orientation du support dans un référentiel. Par exemple, la grandeur physique est la vitesse d’un véhicule automobile comportant le dispositif électroacoustique.
Le référentiel peut être un référentiel absolu. Un « référentiel absolu » désigne un référentiel géodésique dans lequel on peut définir la localisation d’un objet sur terre de manière univoque. Le référentiel absolu peut être choisi parmi les suivants : Réseau Géodésique Français 1993 (RGF93), World Geodetic System (WGS84), International Terrestrial Rotational Service (ITRS) ou European Terrestrial Reference System (ETRS). The physical quantity can characterize the support. For example, the physical quantity can be chosen from the speed of the support with respect to a frame of reference and the position and / or orientation of the support in a frame of reference. For example, the physical quantity is the speed of a motor vehicle comprising the electroacoustic device. The repository can be an absolute repository. An “absolute frame of reference” designates a geodetic frame of reference in which the location of an object on earth can be defined unambiguously. The absolute reference can be chosen from the following: French Geodetic Network 1993 (RGF93), World Geodetic System (WGS84), International Terrestrial Rotational Service (ITRS) or European Terrestrial Reference System (ETRS).
L’unité de mesure peut être reliée à l’unité d’analyse au moyen d’un câble électrique. En variante, la connexion entre l’unité de mesure et l’unité d’analyse peut être opérée par une liaison par ondes électromagnétiques. The measurement unit can be connected to the analysis unit by means of an electric cable. Alternatively, the connection between the measurement unit and the analysis unit can be made by an electromagnetic wave link.
Le dispositif électroacoustique peut comporter l’unité de mesure. Selon une autre variante, l’unité de mesure peut être distante du dispositif. The electroacoustic device may include the unit of measurement. According to another variant, the measurement unit can be remote from the device.
Par exemple, le support est une surface d’un véhicule automobile et l’unité de mesure est disposée dans la boîte de vitesses et est configurée pour convertir la vitesse de l’arbre du moteur en la vitesse du véhicule, ou est disposée dans une roue du véhicule et est configurée pour mesurer la vitesse de rotation de la roue et la convertir en la vitesse du véhicule. For example, the support is a surface of a motor vehicle and the measuring unit is disposed in the gearbox and is configured to convert the speed of the motor shaft to the speed of the vehicle, or is disposed in a wheel of the vehicle and is configured to measure the rotational speed of the wheel and convert it to the speed of the vehicle.
L’unité de mesure peut être un émetteur/récepteur GPS configuré pour mesurer la position et/ou l’orientation du support. The measurement unit can be a GPS transmitter / receiver configured to measure the position and / or orientation of the media.
La grandeur physique peut caractériser le liquide. Par exemple, elle peut être l’aire du liquide recouvrant le support ou l’épaisseur du liquide. The physical quantity can characterize the liquid. For example, it can be the area of the liquid covering the support or the thickness of the liquid.
Elle peut encore caractériser l’environnement du support. Par exemple, lorsque le support est mobile dans un référentiel, la grandeur physique peut être la vitesse d’un fluide, par exemple de l’air, en écoulement autour du support. Une unité de mesure apte à mesurer la vitesse du fluide est par exemple une sonde de Pito ou un capteur MEMs qui peut être montée sur le support. It can still characterize the environment of the medium. For example, when the medium is mobile in a frame of reference, the physical quantity can be the speed of a fluid, for example air, flowing around the medium. A measurement unit capable of measuring the speed of the fluid is, for example, a Pito probe or an MEMs sensor which can be mounted on the support.
De préférence, le dispositif comporte une pluralité d’unités de mesure telles que décrites précédemment. Preferably, the device comprises a plurality of measurement units as described above.
Par ailleurs, afin d’améliorer l’estimation de l’orientation de la force externe, le dispositif peut comporter un module de communication configuré pour communiquer avec un serveur de données à distance et pour recevoir du serveur de données une information météorologique, par exemple la vitesse moyenne et/ou l’orientation moyenne du vent, relativement à la position et/ou à l’orientation du support. Le module de communication
peut notamment comporter un moyen de télécommunication, notamment cellulaire, pour communiquer avec le serveur de données. Furthermore, in order to improve the estimation of the orientation of the external force, the device may include a communication module configured to communicate with a remote data server and to receive meteorological information from the data server, for example. the mean speed and / or the mean orientation of the wind, relative to the position and / or the orientation of the support. The communication module may in particular include a means of telecommunication, in particular cellular, for communicating with the data server.
De préférence, l’unité d’analyse est configurée pour estimer l’orientation de la force externe au moyen d’un modèle numérique d’estimation prenant en données d’entrée la grandeur physique, l’orientation du support par rapport à l’horizontale et optionnellement l’information météorologique fournie par le module de communication. Preferably, the analysis unit is configured to estimate the orientation of the external force by means of a digital estimation model taking as input data the physical quantity, the orientation of the support with respect to the horizontal and optionally the meteorological information provided by the communication module.
En variante ou de manière additionnelle, le module de communication peut être configuré pour communiquer avec au moins un autre dispositif distant qui est muni d’une unité d’analyse configurée pour estimer l’orientation de la force externe s’appliquant sur le liquide, le module de communication étant en outre configuré pour recevoir l’estimation de l’orientation de la force externe en provenance de l’unité d’analyse de l’autre dispositif. As a variant or additionally, the communication module can be configured to communicate with at least one other remote device which is provided with an analysis unit configured to estimate the orientation of the external force applied to the liquid, the communication module being further configured to receive the estimate of the orientation of the external force from the analysis unit of the other device.
Le dispositif et l’autre dispositif peuvent être distants de plus de 1 m, voire de plus de 5 m et/ou de moins de 1 km, voire de moins de 100 m. The device and the other device may be more than 1 m apart, or even more than 5 m and / or less than 1 km, or even less than 100 m.
Par exemple, le dispositif est monté sur un véhicule automobile et l’autre dispositif est monté sur un autre véhicule automobile. Les véhicules peuvent suivent un même trajet et le dispositif monté sur le véhicule en amont sur le trajet peut transmettre l’estimation de la force externe au dispositif monté sur le véhicule en aval. For example, the device is mounted on a motor vehicle and the other device is mounted on another motor vehicle. Vehicles can follow the same path and the device mounted on the vehicle upstream in the path can transmit the estimate of the external force to the device mounted on the vehicle downstream.
De manière routinière, l’homme du métier sait mettre au point un tel modèle d’estimation. Par exemple, dans une variante où le support est porté par un véhicule ou est une surface d’un véhicule, l’homme du métier peut déterminer les trajectoires d’écoulement de l’air en différentes zones de l’enveloppe d’un véhicule se déplaçant à une vitesse déterminée, à partir d’un essai aérodynamique en soufflerie. Il peut en outre déterminer la vitesse locale de l’écoulement d’air en chacune desdites zones, et calculer ainsi une estimation de l’effort s’appliquant sur le liquide dans chacune des zones. Routinely, a person skilled in the art knows how to develop such an estimation model. For example, in a variant where the support is carried by a vehicle or is a surface of a vehicle, those skilled in the art can determine the air flow paths in different zones of the envelope of a vehicle. moving at a determined speed, based on an aerodynamic test in a wind tunnel. It can further determine the local velocity of the air flow in each of said zones, and thereby calculate an estimate of the force applied to the liquid in each of the zones.
Par exemple, l’unité d’analyse peut estimer l’orientation de la force externe s’appliquant sur un liquide, par exemple des gouttes de pluie, sur la face externe d’un support tel un pare-brise ou un organe de protection d’un capteur d’un véhicule, à partir de la mesure de la vitesse du véhicule, de l’orientation du véhicule transmise par un émetteur/récepteur GPS, et de la vitesse moyenne et de l’orientation moyenne du vent obtenues du serveur de données.
Le déplacement du liquide induit par l’onde de surface ultrasonore peut notamment résulter d’un effet de streaming acoustique et/ou d’un effet de pression de radiation induits par la ou les ondes de surface ultrasonore. For example, the analysis unit can estimate the orientation of the external force applied to a liquid, for example raindrops, on the external face of a support such as a windshield or a protective member. a sensor of a vehicle, from the measurement of the speed of the vehicle, the orientation of the vehicle transmitted by a GPS transmitter / receiver, and the average speed and the average direction of the wind obtained from the server of data. The displacement of the liquid induced by the ultrasonic surface wave can in particular result from an acoustic streaming effect and / or from a radiation pressure effect induced by the ultrasonic surface wave (s).
Le liquide peut se présenter sous la forme d’au moins une goutte, ou sous la forme d’une pluralité de gouttes pouvant présenter des tailles différentes. Le liquide peut se présenter sous la forme d’au moins un film, continu ou discontinu. Par « film », on entend une pellicule mince formée sur le support. Le liquide peut se présenter sous la forme d’une flaque. The liquid can be in the form of at least one drop, or in the form of a plurality of drops which may be of different sizes. The liquid can be in the form of at least one film, continuous or discontinuous. By “film” is meant a thin film formed on the support. The liquid may be in the form of a puddle.
Le liquide peut être aqueux. En particulier, il peut être de l’eau de pluie ou de l’eau de rosée. L’eau de pluie et/ou l’eau de rosée peut notamment contenir des particules grasses. Une eau de rosée forme une buée en surface d’un support. Elle résulte de la condensation sur le support, dans des conditions ad hoc de pression et de température, de l’eau sous forme vapeur contenue dans l’air. The liquid can be aqueous. In particular, it can be rainwater or dew water. Rainwater and / or dew water may in particular contain fatty particles. Dew water forms a mist on the surface of a support. It results from the condensation on the support, under appropriate pressure and temperature conditions, of water in vapor form contained in the air.
Le dispositif peut comporter une unité de détection configurée pour détecter la présence du liquide sur le support. Par exemple, l’unité de détection peut être configurée pour traiter un flux d'images acquises par une caméra et pour déceler lorsque la caméra est aveuglée par le liquide. L’unité de détection peut être configurée pour traiter un flux d'informations d'un LiDAR afin de détecter la réduction du portée du LiDAR induite par le liquide. The device may include a detection unit configured to detect the presence of the liquid on the support. For example, the detection unit can be configured to process a stream of images acquired by a camera and to detect when the camera is blinded by liquid. The sensing unit can be configured to process a flow of information from a LiDAR to detect the liquid-induced reduction in LiDAR range.
Par ailleurs, l’unité de détection peut être configurée pour mesurer et analyser une onde de surface émise par au moins l’un des transducteurs, afin de détecter la présence du liquide au contact du support. Par exemple, l’unité de détection peut être configurée pour mesurer l’onde transmise entre deux des transducteurs disposés en face l’un de l’autre sur le support. Selon un autre exemple, le dispositif peut être configuré pour que l’un des transducteurs génère une onde ultrasonore sous la forme d’une impulsion, par exemple un créneau ou un Dirac, et pour mesurer si une onde de réponse est produite par interaction entre le liquide et l’impulsion, si le liquide est en contact du support. Furthermore, the detection unit can be configured to measure and analyze a surface wave emitted by at least one of the transducers, in order to detect the presence of the liquid in contact with the support. For example, the detection unit can be configured to measure the wave transmitted between two of the transducers arranged opposite each other on the support. According to another example, the device can be configured so that one of the transducers generates an ultrasonic wave in the form of a pulse, for example a pulse or a Dirac, and to measure whether a response wave is produced by interaction between the liquid and the impulse, if the liquid is in contact with the support.
Enfin les transducteurs à ondes de surface peuvent eux même être utilisés pour détecter la présence du liquide sur le support, soit en mesurant la transmission du signal entre deux transducteurs situés l’un en face de l’autre, soit en envoyant des puises et en mesurant l’écho généré par la réflexion de l’onde par le liquide.
Le support peut être en tout matériau apte à propager une onde de surface ultrasonore. De préférence, il est en un matériau pour lequel la longueur d’absorption de l’onde de surface ultrasonore dans le matériau est au moins plus de 10 fois, voire au moins plus de 100 fois supérieure à la surface du support Finally, surface wave transducers can themselves be used to detect the presence of liquid on the support, either by measuring the signal transmission between two transducers located opposite each other, or by sending pulses and measuring the echo generated by the reflection of the wave by the liquid. The support can be made of any material capable of propagating an ultrasonic surface wave. Preferably, it is made of a material for which the absorption length of the ultrasonic surface wave in the material is at least more than 10 times, or even at least more than 100 times greater than the surface of the support.
La face du support sur laquelle l’onde de surface longitudinale se propage peut être plane. Elle peut aussi être courbe, sous réserve que le rayon de courbure de la face soit supérieur à la longueur d’onde de l’onde de surface ultrasonore. The face of the medium on which the longitudinal surface wave propagates may be planar. It can also be curved, provided that the radius of curvature of the face is greater than the wavelength of the ultrasonic surface wave.
La face peut être rugueuse. Elle peut présenter une rugosité Ra inférieure à la longueur d’onde. The face may be rough. It may have roughness Ra less than the wavelength.
Le support peut notamment se présenter sous la forme d’une plaque plane, ou présentant au moins une courbure selon une direction. L’épaisseur de la plaque peut être inférieure à 10 cm, voire inférieure à 1 cm, voir même inférieure à 1 mm. La longueur de la plaque peut être supérieure à 1 cm, voire supérieure à 10 m, voire même supérieure à 1 m. The support may in particular be in the form of a flat plate, or having at least one curvature in one direction. The thickness of the plate can be less than 10 cm, or even less than 1 cm, or even less than 1 mm. The length of the plate may be greater than 1 cm, or even greater than 10 m, or even greater than 1 m.
Par « épaisseur du support », on considère la plus petite dimension du support mesurée selon une direction perpendiculaire à la surface sur laquelle se propage l’onde ultrasonore. By "thickness of the support", we consider the smallest dimension of the support measured in a direction perpendicular to the surface on which the ultrasonic wave propagates.
Le support peut être disposé à plat par rapport à l’horizontale. En variante, il peut être incliné par rapport à l’horizontale d’un angle a supérieur à 10°, voire supérieur à 20°, voire supérieur à 45°, voire supérieure à 70°. Il peut être disposé verticalement. The support can be laid out flat with respect to the horizontal. As a variant, it may be inclined relative to the horizontal by an angle a greater than 10 °, or even greater than 20 °, or even greater than 45 °, or even greater than 70 °. It can be arranged vertically.
Le support peut être optiquement transparent, notamment à la lumière dans le visible. Le procédé est ainsi alors particulièrement adapté aux applications dans lesquelles l’amélioration du confort visuel d’un utilisateur observant son environnement à travers le support est recherchée. The support can be optically transparent, in particular to light in the visible. The method is thus particularly suitable for applications in which the improvement of the visual comfort of a user observing his environment through the medium is sought.
Le support peut être en un matériau choisi parmi les matériaux piézoélectriques, les polymères, en particulier les thermoplastiques, notamment le polycarbonate, les verres, les métaux et les céramiques. The support can be made of a material chosen from piezoelectric materials, polymers, in particular thermoplastics, in particular polycarbonate, glasses, metals and ceramics.
De préférence, le support est en matériau différent d’un matériau piézoélectrique. Preferably, the support is made of a material other than a piezoelectric material.
De préférence, le support est choisi dans le groupe formé par : Preferably, the support is chosen from the group formed by:
- une surface automobile, par exemple choisie parmi un pare-brise d’un véhicule, un vitrage d’un rétroviseur, ou - an automotive surface, for example chosen from a windshield of a vehicle, a glazing of a rear-view mirror, or
- une visière d’un casque,
- une vitre d’un bâtiment, - a visor of a helmet, - a window of a building,
- une surface d’un dispositif optique, par exemple choisi parmi un objectif d’une caméra, un verre d’une lunette de vue, et un capteur, notamment une sonde, par exemple une sonde de Pitot, ou un lidar, et - a surface of an optical device, for example chosen from a lens of a camera, a glass of a telescope, and a sensor, in particular a probe, for example a Pitot probe, or a lidar, and
- un élément de protection d’un tel capteur. - a protective element for such a sensor.
Le support peut être un élément de la structure d’un aéronef, par exemple une aile, un fuselage ou un empennage. The support can be an element of the structure of an aircraft, for example a wing, a fuselage or an empennage.
Le dispositif comporte au moins deux transducteurs. Afin de définir encore plus précisément l’orientation de la force acoustique, le dispositif comporte de préférence au moins trois, voire au moins quatre, mieux au moins huit transducteurs d’onde, de préférence répartis régulièrement autour d’un axe normal à une face du support. The device has at least two transducers. In order to define even more precisely the orientation of the acoustic force, the device preferably comprises at least three, even at least four, better still at least eight wave transducers, preferably distributed regularly around an axis normal to one face. support.
De préférence, le dispositif comporte au moins deux, voire au moins trois, mieux au moins quatre paires de transducteurs, les transducteurs d’une même paire étant disposés de façon à générer des ondes de surface ultrasonores se propageant dans une même direction mais selon des sens différents. De préférence, les transducteurs d’une même paire sont disposés en regard l’un de l’autre selon la direction de propagation des ondes qu’ils peuvent générer. Preferably, the device comprises at least two, or even at least three, better still at least four pairs of transducers, the transducers of the same pair being arranged so as to generate ultrasonic surface waves propagating in the same direction but in different directions. different meanings. Preferably, the transducers of the same pair are arranged facing each other according to the direction of propagation of the waves that they can generate.
Le dispositif peut comporter un nombre pair de transducteurs. The device may include an even number of transducers.
Les transducteurs peuvent être fixés, et de préférence collés, sur le support. En particulier, ils peuvent être disposés sur un bord du support. The transducers can be fixed, and preferably glued, to the support. In particular, they can be arranged on an edge of the support.
Les transducteurs peuvent recouvrir au moins partiellement le support, en particulier la face du support sur laquelle repose le liquide. The transducers can at least partially cover the support, in particular the face of the support on which the liquid rests.
Au moins l’un des transducteurs, voire chacun des transducteurs, peut générer directement l’onde de surface ultrasonore. En variante, au moins l’un des transducteurs, voire chacun des transducteurs, peut générer une onde guidée ultrasonore, qui se propage à l’interface entre le support et le transducteur, puis se transforme en l’onde de surface ultrasonore le long d’une portion du support disposée à distance dudit transducteur. At least one of the transducers, or even each of the transducers, can directly generate the ultrasonic surface wave. Alternatively, at least one of the transducers, or even each of the transducers, can generate an ultrasonic guided wave, which propagates at the interface between the medium and the transducer, and then transforms into the ultrasonic surface wave along it. a portion of the support disposed at a distance from said transducer.
Au moins l’un des transducteurs, voire chaque transducteur, peut être en contact direct avec le support ou avec une couche intermédiaire, par exemple formée d’adhésif, disposée sur le support. At least one of the transducers, or even each transducer, may be in direct contact with the support or with an intermediate layer, for example formed of adhesive, disposed on the support.
De préférence, au moins l’un des transducteurs, de préférence chaque transducteur comporte des première et deuxième électrodes formant respectivement des
premier et deuxième peignes, les premier et deuxième peignes étant interdigités et étant disposés sur le support et/ou disposés au contact direct du support et/ou au contact d’un substrat intermédiaire en contact avec, notamment disposé sur, le support, le substrat étant en un matériau piézoélectrique. Preferably, at least one of the transducers, preferably each transducer comprises first and second electrodes respectively forming first and second combs, the first and second combs being interdigitated and being arranged on the support and / or placed in direct contact with the support and / or in contact with an intermediate substrate in contact with, in particular placed on, the support, the substrate being made of a piezoelectric material.
Le matériau piézoélectrique peut être choisi dans le groupe formé par le niobate de lithium, le nitrure d’aluminium, le titano-zircanate de plomb, l’oxyde de zinc, et leurs mélanges. Le matériau piézoélectrique peut être opaque à la lumière dans le visible. The piezoelectric material can be selected from the group consisting of lithium niobate, aluminum nitride, lead titanozircanate, zinc oxide, and mixtures thereof. The piezoelectric material can be opaque to light in the visible.
Dans une variante, le support est formé du matériau piézoélectrique et au moins l’un des transducteurs comporte le support. Les premier et deuxième peignes sont alors de préférence disposés au contact du support. Alternatively, the support is formed from the piezoelectric material and at least one of the transducers includes the support. The first and second combs are then preferably placed in contact with the support.
Dans une autre variante, le support est en un matériau différent d’un matériau piézoélectrique et les électrodes sont disposées sur le substrat intermédiaire. In another variant, the support is made of a material other than a piezoelectric material and the electrodes are arranged on the intermediate substrate.
Les première et deuxième électrodes peuvent être déposées par photolithographie sur le support et/ou sur le substrat. The first and second electrodes can be deposited by photolithography on the support and / or on the substrate.
Les première et deuxième électrodes peuvent être prises en sandwich entre le support et le substrat, qui de préférence présente une épaisseur au moins une fois, voire au moins deux fois supérieure à la longueur d’onde fondamentale de l’onde guidée ultrasonore. En variante, le substrat peut être pris en sandwich entre le support et les première et deuxième électrodes, et présente de préférence une épaisseur inférieure à la longueur d’onde fondamentale de l’onde guidée ultrasonore. The first and second electrodes can be sandwiched between the support and the substrate, which preferably has a thickness at least once or even at least twice as much as the fundamental wavelength of the ultrasonic guided wave. Alternatively, the substrate can be sandwiched between the support and the first and second electrodes, and preferably has a thickness less than the fundamental wavelength of the ultrasonic guided wave.
Les premier et deuxième peignes peuvent comporter de préférence une base à partir de laquelle s’étend une rangée de doigts, les doigts étant de préférence parallèle les uns aux autres. Les doigts peuvent présenter une largeur comprise entre un huitième de la longueur d’onde de l’onde de surface ultrasonore et la moitié de ladite longueur d’onde, de préférence égale à un quart de ladite longueur d’onde. La largeur des doigts détermine en partie la fréquence fondamentale de l’onde de surface ultrasonore. The first and second combs may preferably have a base from which extends a row of fingers, the fingers preferably being parallel to each other. The fingers may have a width of between one-eighth of the wavelength of the ultrasonic surface wave and half of said wavelength, preferably equal to one-quarter of said wavelength. The width of the fingers partly determines the fundamental frequency of the ultrasonic surface wave.
Par ailleurs, l’espacement entre deux doigts consécutivement adjacents d’une rangée du premier peigne, respectivement du deuxième peigne, peut être comprise entre un huitième de la longueur d’onde de l’onde de surface ultrasonore et la moitié de ladite longueur d’onde, de préférence égale à un quart de ladite longueur d’onde. Furthermore, the spacing between two consecutively adjacent fingers of a row of the first comb, respectively of the second comb, may be between one eighth of the wavelength of the ultrasonic surface wave and half of said length d 'wave, preferably equal to a quarter of said wavelength.
La rangée de doigts du premier peigne et/ou la rangée de doigts du deuxième peigne peuvent comporter chacun plus de 2 doigts, voire plus de 10 doigts, voire même plus
de 40 doigts. L’augmentation du nombre de doigts augmente le facteur de qualité du transducteur. The row of fingers of the first comb and / or the row of fingers of the second comb may each comprise more than 2 fingers, or even more than 10 fingers, or even more. 40 fingers. Increasing the number of fingers increases the quality factor of the transducer.
Le substrat peut être une couche mince déposée, par exemple par dépôt chimique en phase vapeur ou par pulvérisation sur le support. En variante, le substrat peut être autoporteur, c’est-à-dire suffisamment rigide pour ne pas fléchir sous l’effet de son propre poids. Le substrat autoporteur peut être fixé, par exemple collé, sur le support. The substrate can be a thin film deposited, for example by chemical vapor deposition or by spraying on the support. Alternatively, the substrate can be self-supporting, that is, sufficiently rigid not to flex under the effect of its own weight. The self-supporting substrate can be fixed, for example glued, on the support.
La portion du liquide la plus éloignée du transducteur peut être disposée à une distance correspondant à plusieurs fois la longueur d’atténuation de l’onde de surface dans le support. The portion of the liquid furthest from the transducer can be disposed at a distance several times the attenuation length of the surface wave in the holder.
Par ailleurs, le dispositif peut comporter un générateur électrique, par exemple une batterie, pour alimenter électriquement chaque transducteur. Le générateur peut être relié à l’unité de contrôle. Il peut alimenter l’unité d’analyse. Furthermore, the device may include an electric generator, for example a battery, to supply each transducer electrically. The generator can be connected to the control unit. It can power the analysis unit.
Le générateur électrique peut délivrer à au moins l’un des transducteurs, voire à chacun des transducteurs, une puissance comprise entre 10 milliwatts et 50 watts. The electrical generator can deliver at least one of the transducers, or even each of the transducers, a power between 10 milliwatts and 50 watts.
Enfin, l’invention concerne encore un véhicule automobile choisi parmi une voiture, un bus, une motocyclette et un camion, le véhicule comportant un dispositif selon l’invention. Finally, the invention also relates to a motor vehicle chosen from among a car, a bus, a motorcycle and a truck, the vehicle comprising a device according to the invention.
De préférence, le véhicule comporte un châssis et le dispositif est fixe par rapport au châssis. Preferably, the vehicle comprises a frame and the device is fixed relative to the frame.
L’invention concerne aussi un procédé comportant la fourniture d’un dispositif, notamment tel que selon l’invention, comportant un support recouvert d’un liquide et au moins deux transducteurs d’onde couplés acoustiquement avec le support et étant configurés chacun pour générer une onde de surface ultrasonore se propageant dans le support, les directions de propagation des ondes de surface ultrasonores générées par les transducteurs étant différentes, le procédé comportant l’estimation de l’orientation de la force externe s’appliquant sur le liquide, et en fonction de ladite estimation, l’alimentation électrique d’au moins un des transducteurs pour propager une ou des ondes de surface ultrasonores dans le support de manière que la force acoustique s’appliquant sur le liquide, produite par l’interaction entre la ou les ondes de surface ultrasonores et le liquide, soit orientée dans un sens prédéterminé. The invention also relates to a method comprising the provision of a device, in particular as according to the invention, comprising a support covered with a liquid and at least two wave transducers acoustically coupled with the support and each being configured to generate an ultrasonic surface wave propagating in the medium, the directions of propagation of the ultrasonic surface waves generated by the transducers being different, the method comprising estimating the orientation of the external force applied to the liquid, and by depending on said estimate, the power supply of at least one of the transducers to propagate one or more ultrasonic surface waves in the support so that the acoustic force applied to the liquid, produced by the interaction between the one or more ultrasonic surface waves and liquid, or oriented in a predetermined direction.
De préférence, le dispositif est monté sur un véhicule automobile et l’estimation de la force externe comporte la mesure de la vitesse du véhicule.
L’invention concerne enfin un véhicule automobile comportant un capteur de vitesse du véhicule et un dispositif électroacoustique, notamment selon l’invention, comportant : Preferably, the device is mounted on a motor vehicle and the estimation of the external force comprises the measurement of the speed of the vehicle. The invention finally relates to a motor vehicle comprising a vehicle speed sensor and an electroacoustic device, in particular according to the invention, comprising:
- un support, - a support,
- au moins deux transducteurs d’onde couplés acoustiquement avec le support et étant configurés chacun pour générer une onde de surface ultrasonore se propageant dans le support, les directions de propagation des ondes de surface ultrasonores générées par les transducteurs étant différentes, et - at least two wave transducers acoustically coupled with the support and each being configured to generate an ultrasonic surface wave propagating in the support, the directions of propagation of the ultrasonic surface waves generated by the transducers being different, and
- une unité de contrôle configurée pour commander, au moyen de la vitesse du véhicule, au moins l’un des transducteurs de manière que, lorsqu’un liquide est disposé sur le support, la force acoustique s’appliquant sur le liquide, produite par l’interaction entre la ou les ondes de surface ultrasonores et le liquide soit orientée dans un sens prédéterminé. - a control unit configured to control, by means of the speed of the vehicle, at least one of the transducers so that, when a liquid is placed on the support, the acoustic force applied to the liquid, produced by the interaction between the ultrasonic surface wave (s) and the liquid is oriented in a predetermined direction.
L’invention pourra être mieux comprise à la lecture de la description détaillée qui va suivre, d’exemples de mise en œuvre non limitatifs de celle-ci, et à l’examen du dessin annexé, sur lequel : The invention may be better understood from reading the detailed description which follows, of non-limiting examples of implementation thereof, and by examining the appended drawing, in which:
[Fig 1] la figure 1 représente, selon une vue en perspective, un véhicule automobile comportant un exemple de dispositif selon l’invention, [Fig 1] Figure 1 shows, in a perspective view, a motor vehicle comprising an example of a device according to the invention,
[Fig 2] la figure 2 est un agrandissement de la figure 1 représentant une portion du dispositif selon l’invention, [Fig 2] Figure 2 is an enlargement of Figure 1 showing a portion of the device according to the invention,
[Fig 3] la figure 3 est une représentation schématique du dispositif de l’exemple[Fig 3] Figure 3 is a schematic representation of the device of the example
1, 1,
[Fig 4] la figure 4 illustre un exemple de méthode pour choisir les transducteurs à activer, [Fig 4] Figure 4 illustrates an example of a method for choosing the transducers to activate,
[Fig 5] la figure 5 représente un mode de réalisation d’un transducteur d’un exemple de dispositif, et [Fig 5] Figure 5 shows an embodiment of a transducer of an example device, and
[Fig 6] la figure 6 représente un autre mode de réalisation d’un transducteur d’un exemple de dispositif. [Fig 6] Figure 6 shows another embodiment of a transducer of an exemplary device.
Les éléments constitutifs du dessin n’ont pas été représentés à l’échelle par souci de clarté. The constituent parts of the drawing have not been shown to scale for the sake of clarity.
La figure 1 représente un véhicule automobile 5 qui contient un exemple de dispositif 10 selon l’invention.
Le dispositif comporte une pluralité de transducteurs d’onde de surface ultrasonore 15a-h et un support 20, défini par un hublot monté dans une fenêtre 25 ménagée dans un boitier de protection 30 d’un lidar, sur lequel sont disposés les transducteurs. Le dispositif comporte en outre une unité d’analyse 35 et une unité de contrôle 40 des transducteurs, toutes deux logées dans le véhicule. FIG. 1 represents a motor vehicle 5 which contains an example of a device 10 according to the invention. The device comprises a plurality of ultrasonic surface wave transducers 15a-h and a support 20, defined by a porthole mounted in a window 25 formed in a protective case 30 of a lidar, on which the transducers are arranged. The device further comprises an analysis unit 35 and a control unit 40 of the transducers, both housed in the vehicle.
Le hublot est transparent à la lumière visible et est par exemple en verre ou en poly carbonate. The window is transparent to visible light and is for example made of glass or polycarbonate.
Un lidar est logé dans le boîtier de protection et émet un faisceau laser L à travers le hublot, afin de détecter les obstacles 45, les piétons et les autres véhicules situés dans l’environnement du véhicule. Dans l’exemple illustré, le hublot est plan, mais dans une variante, il peut être courbe. A lidar is housed in the protective housing and emits an L laser beam through the window, in order to detect obstacles 45, pedestrians and other vehicles located in the vicinity of the vehicle. In the example illustrated, the window is flat, but in a variant, it can be curved.
Les transducteurs sont disposés sur le contour de la face externe 50 du hublot, exposée au vent et à la pluie. Ils sont par ailleurs disposés de manière régulière autour de l’axe X passant par le centre C du hublot et qui est perpendiculaire à la face. Ainsi, les transducteurs, par exemple référencés 15a et 15e , disposés symétriquement par rapport au centre forment des paires, chaque transducteur d’une paire émettant une onde de surface ultrasonore, par exemple Wa, dans un sens opposée au sens de l’onde, par exemple We, émise par le transducteur de l’autre paire. The transducers are arranged on the contour of the external face 50 of the window, exposed to the wind and to the rain. They are also arranged regularly around the axis X passing through the center C of the window and which is perpendicular to the face. Thus, transducers, for example referenced 15 a and 15 e, arranged symmetrically relative to the center form pairs, each transducer of a pair of ultrasonic wave emitting surface, e.g. Wa, in an opposite direction to the direction of the wave, for example We, emitted by the transducer of the other pair.
Dans l’exemple illustré sur la figure 1, chaque transducteur est configuré pour propager une onde de surface ultrasonore Wa e orientée sensiblement vers le centre C. Ainsi, quelque soit l’orientation estimée de la force externe projetée sur le support, au moins un des transducteurs du dispositif peut être commandé pour générer une onde de surface apte à induire une force acoustique dont la composante projetée sur le support est orientée sensiblement parallèlement à la force externe projetée. In the example illustrated in FIG. 1, each transducer is configured to propagate an ultrasonic surface wave W ae oriented substantially towards the center C. Thus, whatever the estimated orientation of the external force projected onto the support, at least one transducers of the device can be controlled to generate a surface wave capable of inducing an acoustic force whose component projected onto the support is oriented substantially parallel to the projected external force.
Bien évidemment, d’autres agencements des transducteurs peuvent être envisagés. De même, le nombre de transducteurs n’est pas limitatif, et peut être réduit ou augmenté. Obviously, other arrangements of the transducers can be envisaged. Likewise, the number of transducers is not limiting, and can be reduced or increased.
L’unité d’analyse est logée dans véhicule, par exemple sous le capot avant ou dans l’habitacle. Elle est connectée au moyen de câbles électriques 53 à une unité de mesure de la vitesse du véhicule 55 disposée dans une roue 60 du véhicule et est configurée pour mesurer la vitesse de rotation de la roue et la convertir en la vitesse du véhicule. L’unité
d’analyse est en outre reliée et à un émetteur/récepteur GPS 65 qui mesure la position et l’orientation du véhicule, et qui peut en outre estimer la vitesse du véhicule. The analysis unit is housed in the vehicle, for example under the front hood or in the passenger compartment. It is connected by means of electric cables 53 to a vehicle speed measuring unit 55 arranged in a wheel 60 of the vehicle and is configured to measure the rotational speed of the wheel and convert it into the speed of the vehicle. Unity analysis is further connected and to a GPS transmitter / receiver 65 which measures the position and orientation of the vehicle, and which can further estimate the speed of the vehicle.
Ainsi, selon une fréquence d’acquisition prédéterminée, par exemple supérieure à 1 Hz, voire supérieure à 10 Hz , par exemple égale à 50 Hz, l’unité d’analyse peut recevoir la vitesse, l’orientation et la position du véhicule. Thus, according to a predetermined acquisition frequency, for example greater than 1 Hz, or even greater than 10 Hz, for example equal to 50 Hz, the analysis unit can receive the speed, orientation and position of the vehicle.
Par ailleurs, l’unité d’analyse est reliée à un module de communication cellulaire 70 pour interroger un serveur de données météorologiques distant et recevoir du serveur l’orientation et la vitesse du vent, dans la position du véhicule. Furthermore, the analysis unit is connected to a cellular communication module 70 to interrogate a remote weather data server and receive from the server the direction and speed of the wind, in the position of the vehicle.
L’unité d’analyse estime l’orientation de la force externe au moyen d’un modèle numérique d’estimation prenant en données d’entrée la vitesse, la position et l’orientation du véhicule et l’information météorologique. Le modèle d’estimation tient aussi compte de la position du hublot par rapport à l’horizontale pour estimer la composante liée au poids du liquide. The analysis unit estimates the orientation of the external force using a digital estimation model taking as input the speed, vehicle position and orientation, and weather information. The estimation model also takes into account the position of the window relative to the horizontal to estimate the component related to the weight of the liquid.
Ainsi, lorsqu’un liquide 88 est détecté sur la face du hublot, par exemple par temps de pluie, G unité d’analyse peut estimer l’orientation OFe de la force externe et la transmettre à l’unité de contrôle 40. Thus, when a liquid 88 is detected on the face of the window, for example in rainy weather, G analysis unit can estimate the orientation OF e of the external force and transmit it to the control unit 40.
L’unité de contrôle est reliée électriquement à l’unité d’analyse et à un générateur de courant 75 multivoie. Chaque voie 80a-h du générateur de courant est reliée électriquement à un transducteur 15a-h correspondant pour assurer l’alimentation électrique du transducteur. L’unité de contrôle comporte en outre une pluralité de commutateurs 85a- h, chacun disposé électriquement entre le générateur de courant et le transducteur. The control unit is electrically connected to the analysis unit and to a multi-channel current generator 75. Each 80a-h channel of the current generator is electrically connected to a corresponding 15a-h transducer to supply power to the transducer. The control unit further includes a plurality of switches 85ah, each electrically disposed between the current generator and the transducer.
L’unité de contrôle comporte en outre un module de synthèse 90. Le module de synthèse choisit, parmi l’ensemble des transducteurs du dispositif, les transducteurs générant une onde de surface ultrasonore présentant un angle a inférieur à 90° avec l’orientation de la force externe projetée OFep sur le support. Par exemple, sur la figure 3, les transducteurs 15d, 15e et 15f sont choisis car ils présentent des angles otd-f inférieurs à 90°. L’unité de contrôle dispose ensuite les commutateurs des circuits électriques d’alimentation des transducteurs choisis en position ouverte et les autres commutateurs en position fermée. Il commande ensuite le générateur de courant pour que l’intensité du courant transmis à chacun des transducteurs choisis soit proportionnelle à l’angle a. Ainsi, la force acoustique générée par l’interaction entre les ondes acoustiques des transducteurs choisis et le liquide, projetée sur le support OFap, est sensiblement parallèle et orientée dans le même sens que la force
externe projetée sur le support. Le liquide est alors soumis à une force d’intensité plus élevée que la seule force externe, ce qui facilite son décollement et son déplacement sur le support. The control unit further comprises a synthesis module 90. The synthesis module chooses, from among all the transducers of the device, the transducers generating an ultrasonic surface wave having an angle α of less than 90 ° with the orientation of the device. the projected external force OF ep on the support. For example, in Figure 3, the transducers 15d, 15 e and 15f are selected because they have angles ot df less than 90 °. The control unit then places the switches of the electrical circuits supplying the selected transducers in the open position and the other switches in the closed position. It then controls the current generator so that the intensity of the current transmitted to each of the selected transducers is proportional to the angle α. Thus, the acoustic force generated by the interaction between the acoustic waves of the selected transducers and the liquid, projected onto the OF ap support, is substantially parallel and oriented in the same direction as the force external projection onto the support. The liquid is then subjected to a force of greater intensity than the only external force, which facilitates its detachment and its displacement on the support.
La figure 5 illustre un exemple d’arrangement d’un des transducteurs sur le support de l’exemple illustré sur la figure 1. Figure 5 illustrates an example of the arrangement of one of the transducers on the support of the example shown in Figure 1.
Le transducteur comporte un substrat 100 sur lequel sont disposées des première 105 et deuxième 110 électrodes. Le substrat est par exemple en niobate de lithium coupe à 128°. The transducer comprises a substrate 100 on which are arranged first 105 and second 110 electrodes. The substrate is for example lithium niobate cut at 128 °.
Les électrodes sont déposées par photolithographie. Elles sont constituées d’une couche d’ accroche au substrat intermédiaire formée de titane et d’épaisseur égale à 20 nm et d’une couche conductrice d’or d’une épaisseur de 100 nm. The electrodes are deposited by photolithography. They consist of a layer of bonding to the intermediate substrate formed of titanium and a thickness equal to 20 nm and a conductive layer of gold with a thickness of 100 nm.
Les première et deuxième électrode forment des premier 115 et deuxième 120 peignes. Chaque peigne comporte une base 125,130 et une rangée de doigts 135,140 s’étendant parallèlement les uns aux autres à partir de la base. Les premier et deuxième peignes sont interdigités. The first and second electrodes form first 115 and second 120 combs. Each comb has a base 125,130 and a row of fingers 135,140 extending parallel to each other from the base. The first and second combs are interdigitated.
L’espacement entre les doigts détermine la fréquence de résonance du transducteur que l’homme du métier sait aisément déterminer. The spacing between the fingers determines the resonant frequency of the transducer which one skilled in the art can easily determine.
La mise sous tension électrique alternative des première et deuxième électrodes induit une réponse mécanique du matériau piézoélectrique disposé entre deux doigts consécutifs des premier et deuxième peignes, qui résulte en la génération d’une onde de surface ultrasonore W qui se propage dans le support selon un sens de propagation P, perpendiculaire aux doigts des premier et deuxième peignes. The alternating electrical voltage of the first and second electrodes induces a mechanical response of the piezoelectric material disposed between two consecutive fingers of the first and second combs, which results in the generation of an ultrasonic surface wave W which propagates in the support according to a direction of propagation P, perpendicular to the fingers of the first and second combs.
La figure 6 illustre un autre arrangement des transducteurs sur le support. Figure 6 illustrates another arrangement of the transducers on the support.
Le transducteur comporte un substrat 100 autoporteur et les première 105 et deuxième 110 électrodes sont déposées sur la face du substrat 50 collée sur le support 100. Lorsqu’un courant électrique parcourt les première et deuxième électrodes, le transducteur génère une onde guidée ultrasonore G, qui se propage entre le support et le substrat. Lorsque l’onde guidée atteint l’extrémité 150 du substrat le long de sa direction de propagation, elle se transforme en une onde de surface ultrasonore W qui se propage dans la portion 160 du support séparée du substrat, sensiblement selon la même direction de propagation que l’onde guidée. La transformation de l’onde guidée en onde de surface résulte de l’absence d’interface entre deux solides dans la portion du support.
L’arrangement du transducteur illustré sur la figure 6 présente l’avantage de protéger les première et deuxième électrodes. Par exemple, le liquide 88 ne pas peut s’écouler sur les électrodes et les oxyder. Par ailleurs, de manière optionnelle, le dispositif illustré sur la figure 4 peut comporter un organe de protection 155 qui définit avec le support un logement pour le transducteur. On évite ainsi que des objets qui percutent le dispositif n’endommagent le transducteur. The transducer comprises a self-supporting substrate 100 and the first 105 and second 110 electrodes are deposited on the face of the substrate 50 bonded to the support 100. When an electric current passes through the first and second electrodes, the transducer generates an ultrasonic guided wave G, which propagates between the support and the substrate. When the guided wave reaches the end 150 of the substrate along its direction of propagation, it is transformed into an ultrasonic surface wave W which propagates in the portion 160 of the support separated from the substrate, in substantially the same direction of propagation. than the guided wave. The transformation of the guided wave into a surface wave results from the absence of an interface between two solids in the portion of the support. The arrangement of the transducer illustrated in FIG. 6 has the advantage of protecting the first and second electrodes. For example, liquid 88 cannot flow over the electrodes and oxidize them. Furthermore, optionally, the device illustrated in FIG. 4 can include a protection member 155 which defines with the support a housing for the transducer. This prevents objects which strike the device from damaging the transducer.
Bien évidemment, l’invention n’est pas limitée aux modes de réalisation et aux exemples présentés à titre illustratif.
Obviously, the invention is not limited to the embodiments and examples presented by way of illustration.
Claims
1. Dispositif électroacoustique (10) comportant : 1. Electroacoustic device (10) comprising:
- un support (50), - a support (50),
- au moins deux transducteurs d’onde (15a-h) couplés acoustiquement avec le support et étant configurés chacun pour générer une onde de surface ultrasonore (Wa-h) se propageant dans le support, les directions de propagation (P) des ondes de surface ultrasonores générées par les transducteurs étant différentes, - at least two wave transducers (15 ah ) acoustically coupled with the support and each being configured to generate an ultrasonic surface wave (W ah ) propagating in the support, the directions of propagation (P) of the ultrasonic surface waves generated by the transducers being different,
- une unité de contrôle (40), le dispositif comportant une unité d’analyse (35) configurée pour estimer l’orientation de la force externe (OFe) s’appliquant sur un liquide, lorsque le liquide est au contact du support et/ou le dispositif étant configuré pour recevoir l’estimation de l’orientation de la force externe, l’unité de contrôle étant configurée pour commander au moins l’un des transducteurs, à partir de l’estimation de l’orientation de la force externe, de manière que la force acoustique s’appliquant sur le liquide, produite par l’interaction entre la ou les ondes de surface ultrasonores et le liquide, soit orientée dans un sens prédéterminé. - a control unit (40), the device comprising an analysis unit (35) configured to estimate the orientation of the external force (OF e ) applied to a liquid, when the liquid is in contact with the support and / or the device being configured to receive the estimate of the orientation of the external force, the control unit being configured to control at least one of the transducers, from the estimate of the orientation of the force external, so that the acoustic force applied to the liquid, produced by the interaction between the ultrasonic surface wave (s) and the liquid, is oriented in a predetermined direction.
2. Dispositif selon la revendication 1, l’unité de contrôle étant configurée pour commander le ou les transducteurs de manière à minimiser l’angle entre l’orientation de la force acoustique projetée sur le support (OFap) et l’orientation estimée de la force externe projetée sur le support (OFep), afin de faciliter le déplacement du liquide sur le support. 2. Device according to claim 1, the control unit being configured to control the transducer or transducers so as to minimize the angle between the orientation of the acoustic force projected onto the support (OF ap ) and the estimated orientation of the external force projected on the support (OF ep ), in order to facilitate the movement of the liquid on the support.
3. Dispositif selon l’une quelconque des revendications 1 et 2, comportant au moins une unité de mesure (55;65) connectée à l’unité d’analyse et configurée pour mesurer au moins une grandeur physique, par exemple choisie parmi la vitesse du support par rapport à un référentiel donné et la position et/ou l’orientation du support dans un référentiel donné. 3. Device according to any one of claims 1 and 2, comprising at least one measurement unit (55; 65) connected to the analysis unit and configured to measure at least one physical quantity, for example chosen from the speed. of the support with respect to a given frame of reference and the position and / or orientation of the support in a given frame of reference.
4. Dispositif selon l’une quelconque des revendications précédentes, comportant un module de communication (70) configuré pour communiquer avec un serveur de données à distance et pour recevoir du serveur de données une information météorologique, par exemple la vitesse moyenne et/ou l’orientation moyenne du vent, relative à la position et/ou à l’orientation du support dans un référentiel, notamment absolu. 4. Device according to any one of the preceding claims, comprising a communication module (70) configured to communicate with a remote data server and to receive meteorological information from the data server, for example the average speed and / or l. 'mean wind direction, relative to the position and / or orientation of the support in a frame of reference, in particular absolute.
5. Dispositif selon l’une quelconque des revendications 3 et 4, l’unité d’analyse étant configurée pour estimer l’orientation de la force externe au moyen d’un modèle
numérique d’estimation prenant en données d’entrée la grandeur physique et optionnellement l’information météorologique. 5. Device according to any one of claims 3 and 4, the analysis unit being configured to estimate the orientation of the external force by means of a model. digital estimation taking as input data the physical quantity and optionally the meteorological information.
6. Dispositif selon l’une quelconque des revendications précédentes, comportant un module de communication configuré 6. Device according to any one of the preceding claims, comprising a configured communication module
- pour communiquer avec au moins un autre dispositif distant comportant une unité d’analyse et tel que défini en revendication 1, et - to communicate with at least one other remote device comprising an analysis unit and as defined in claim 1, and
- pour recevoir l’estimation de l’orientation de la force externe en provenance de l’unité d’analyse de l’autre dispositif. - to receive the estimate of the orientation of the external force from the analysis unit of the other device.
7. Dispositif selon l’une quelconque des revendications précédentes, comportant au moins trois, voire au moins quatre transducteurs d’onde, de préférence répartis régulièrement autour d’un axe normal à une face du support. 7. Device according to any one of the preceding claims, comprising at least three, or even at least four wave transducers, preferably distributed regularly around an axis normal to one face of the support.
8. Dispositif selon l’une quelconque des revendications précédentes, la fréquence fondamentale de l’onde de surface ultrasonore générée par au moins l’un des transducteurs, étant comprise entre 0,1 MHz et 1000 MHz, de préférence comprise entre 10 MHz et 100 MHz, par exemple égale à 40 MHz. 8. Device according to any one of the preceding claims, the fundamental frequency of the ultrasonic surface wave generated by at least one of the transducers, being between 0.1 MHz and 1000 MHz, preferably between 10 MHz and 100 MHz, for example equal to 40 MHz.
9. Dispositif selon l’une quelconque des revendications précédentes, le support étant transparent ou translucide. 9. Device according to any one of the preceding claims, the support being transparent or translucent.
10. Dispositif selon l’une quelconque des revendications précédentes, le support étant en un matériau choisi parmi les matériaux piézoélectriques, les polymères, en particulier les thermoplastiques, les verres, les métaux et les céramiques. 10. Device according to any one of the preceding claims, the support being made of a material chosen from piezoelectric materials, polymers, in particular thermoplastics, glasses, metals and ceramics.
11. Dispositif selon l’une quelconque des revendications précédentes, le support étant choisi dans le groupe formé par 11. Device according to any one of the preceding claims, the support being chosen from the group formed by
- une surface automobile, par exemple choisie parmi un pare-brise d’un véhicule, un vitrage d’un rétroviseur, - an automotive surface, for example chosen from a vehicle windshield, a mirror glazing,
- une visière d’un casque, - a helmet visor,
- une vitre d’un bâtiment, - a window of a building,
- une surface d’un dispositif optique, par exemple choisi parmi un objectif d’une caméra, un verre d’une lunette de vue et un capteur, notamment une sonde, par exemple une sonde de Pitot, et - a surface of an optical device, for example chosen from a lens of a camera, a glass of a telescope and a sensor, in particular a probe, for example a Pitot probe, and
- un élément de protection d’un tel dispositif optique.
- a protective element of such an optical device.
12. Dispositif selon l’une quelconque des revendications précédentes, le transducteur étant en contact direct avec le support ou avec une couche intermédiaire, par exemple formée d’adhésif, disposée sur le support. 12. Device according to any one of the preceding claims, the transducer being in direct contact with the support or with an intermediate layer, for example formed of adhesive, arranged on the support.
13. Dispositif selon la revendication précédente, le transducteur comportant des première et deuxième électrodes formant respectivement des premier (115) et deuxième (120) peignes, les premier et deuxième peignes étant interdigités et disposés au contact direct du support et/ou au contact d’un substrat (100) intermédiaire en contact avec, notamment disposé sur, le support, le substrat étant en un matériau piézoélectrique, en particulier choisi dans le groupe formé par le niobate de lithium, le nitrure d’aluminium, le titano-zircanate de plomb, l’oxyde de zinc, et leurs mélanges. 13. Device according to the preceding claim, the transducer comprising first and second electrodes respectively forming first (115) and second (120) combs, the first and second combs being interdigitated and arranged in direct contact with the support and / or in contact with 'an intermediate substrate (100) in contact with, in particular disposed on, the support, the substrate being made of a piezoelectric material, in particular chosen from the group formed by lithium niobate, aluminum nitride, titano-zircanate lead, zinc oxide, and mixtures thereof.
14. Véhicule automobile (5) choisi parmi une voiture, un bus, une motocyclette et un camion, le véhicule comportant un dispositif selon l’une quelconque des revendications précédentes. 14. Motor vehicle (5) selected from a car, a bus, a motorcycle and a truck, the vehicle comprising a device according to any one of the preceding claims.
15. Véhicule automobile comportant un capteur de vitesse du véhicule et un dispositif électroacoustique comportant 15. Motor vehicle comprising a vehicle speed sensor and an electroacoustic device comprising
- un support (50), - a support (50),
- au moins deux transducteurs d’onde (15a-h) couplés acoustiquement avec le support et étant configurés chacun pour générer une onde de surface ultrasonore (Wa-h) se propageant dans le support, les directions de propagation (P) des ondes de surface ultrasonores générées par les transducteurs étant différentes, - at least two wave transducers (15 ah ) acoustically coupled with the support and each being configured to generate an ultrasonic surface wave (W ah ) propagating in the support, the directions of propagation (P) of the ultrasonic surface waves generated by the transducers being different,
- une unité de contrôle (40) configurée pour commander, au moyen de la vitesse du véhicule, au moins l’un des transducteurs de manière que, lorsqu’un liquide est disposé sur le support, la force acoustique produite par l’interaction entre la ou les ondes de surface ultrasonores et le liquide soit orientée dans un sens prédéterminé.
- a control unit (40) configured to control, by means of the speed of the vehicle, at least one of the transducers so that, when a liquid is placed on the support, the acoustic force produced by the interaction between the ultrasonic surface wave (s) and the liquid is oriented in a predetermined direction.
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PCT/EP2020/076758 WO2021058662A1 (en) | 2019-09-25 | 2020-09-24 | Device for cleaning a support member covered with a liquid |
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US12030094B2 (en) * | 2021-12-23 | 2024-07-09 | Volkswagen Aktiengesellschaft | Acousto-vibratory sensor cleaning |
FR3131396B1 (en) * | 2021-12-23 | 2024-03-29 | Valeo Systemes Dessuyage | Detection assembly comprising a sensor and at least one wave transducer for cleaning an optical surface of the sensor |
FR3131234A1 (en) * | 2021-12-23 | 2023-06-30 | Valeo Systèmes D’Essuyage | Device for cleaning a surface |
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GB1372235A (en) * | 1971-05-05 | 1974-10-30 | Secr Defence | Acoustic surface wave devices |
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GB201100290D0 (en) * | 2011-01-10 | 2011-02-23 | Trevett David R M | Clearing precipitation from windaows |
JP5780890B2 (en) * | 2011-08-31 | 2015-09-16 | 株式会社国際電気セミコンダクターサービス | Ultrasonic cleaning method and apparatus |
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GB2518136B (en) * | 2013-07-22 | 2016-09-14 | Echovista Gmbh | Ultrasonically clearing precipitation |
CN103831271A (en) * | 2014-03-19 | 2014-06-04 | 中国科学院声学研究所 | Ultrasonic cavitation cloud control device and ultrasonic cavitation cloud control method |
FR3044937B1 (en) * | 2015-12-09 | 2018-01-12 | Universite De Lille 1 | METHOD FOR PROMOTING SLIDING AT LEAST ONE DROP ON A SUPPORT |
FI127711B (en) * | 2016-05-13 | 2018-12-31 | Altum Tech Oy | A method for cleaning of a device |
EP3460460B1 (en) * | 2016-05-18 | 2024-02-28 | Myongji University Industry and Academia Cooperation Foundation | Cleaning apparatus and method |
US10071400B2 (en) * | 2016-06-20 | 2018-09-11 | Texas Instruments Incorporated | Ultrasonic lens cleaning with travelling wave excitation |
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JP2022550937A (en) | 2022-12-06 |
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