WO2020057817A1

WO2020057817A1 - Detection of snow on a glazed surface of a motor vehicle

Info

Publication number: WO2020057817A1
Application number: PCT/EP2019/070421
Authority: WO
Inventors: Christophe Chassaing; Vincent Gaucher; David Peschard; Patrick ASSUID; Aurélie FRAYSSE; Denis Thebault; Franck DARSES
Original assignee: Valeo Systèmes d'Essuyage
Priority date: 2018-09-19
Filing date: 2019-07-30
Publication date: 2020-03-26
Also published as: FR3085922A1; FR3085922B1

Abstract

The invention relates to a device (100) for detecting snow on a glazed surface (400) of a motor vehicle (500). The detection device (100) comprises at least a first electrode (1) and a second electrode (2) arranged at a distance from one another in the vicinity of the glazed surface (400), and also a member (3) configured to measure an electrical quantity (300) between the first electrode (1) and the second electrode (2).

Description

Snow detection on a glass surface of a motor vehicle

The invention relates to the field of wiping and / or cleaning the glass surfaces of a motor vehicle.

The technical problem to which the present invention proposes to provide a solution is that of detecting snow on such a glazed surface, in order to remove this snow before it disturbs the visibility of the driver and / or passengers, in particular when the glass surface considered is the windshield, and / or before it disturbs the operation or the performance of detectors or optical elements of the vehicle such as, for example, lighting and signaling devices thereof this.

In particular, there are known electrode devices in which the aim is to detect a short circuit generated by a drop of rain forming a conductor between the two electrodes when the rain is in contact with the glass surface. There are thus known rain detection devices integrated in the glazed surface, for example of the windshield, which comprise electrodes entangled one inside the other with constant spacing between them, the electrodes being sufficiently close to one another. the other so that a drop of rain is likely to form the short-circuit necessary for detection. It is understood, however, that this detection has a random nature in that a drop of rain must come into contact with the windshield between two electrodes. However, it is not possible to extend over the entire glass surface this entanglement of electrodes thus integrated in the windshield, because if these are made of the most transparent material possible, they remain visible to the driver and may represent discomfort while driving.

Consequently, the detection devices configured for rain detection have drawbacks. Furthermore, the problem described above of the accumulation of snow on the glass surface and in particular on the windshield is different from that of the rain falling on the windshield, which is discharged at the bottom of the windshield and only has a drawback when the vehicle is running. As a result, the present invention, which aims to solve a specific problem of snow present on the windshield, must find an alternative to the rain detection devices as previously presented. And the present invention aims to provide a simple, reliable and inexpensive solution for this detection of snow on a glass surface.

To achieve its object, the subject of the present invention is a device for detecting snow on a glazed surface of a motor vehicle, characterized in that it comprises at least a first electrode and a second electrode arranged at a distance from one of the other in the vicinity of the glass surface, a measuring device configured to measure an electrical quantity in a detection zone between the first electrode and the second electrode, and at least one central unit configured to compare this measurement of the electrical quantity with at least one threshold value representative of this electrical quantity for a given thickness of snow on the glazed surface in the detection zone.

The present invention applies to any glazed surface of a motor vehicle on which the presence of snow accumulated or in the course of accumulation may hinder the visibility of the driver and / or the passengers of the vehicle, or may disturb the operation or the performance. one or more detectors or optical elements of the vehicle such as, for example, one or more lighting or signaling devices, or optical devices associated with driving assistance systems such as, for example, parking assistance.

The electrical quantity measured by the measuring member of the detection device according to the invention between the first electrode and the second electrode is an electrical quantity whose value is modified by the presence of snow in the region separating the two above-mentioned electrodes. By way of nonlimiting examples, the electrical quantity measured can be an electrical resistance of the ambient medium separating the two previously defined electrodes, or an electrical conductivity of the aforementioned ambient medium.

By the expression "in the vicinity of the glazed surface", it is intended to protect the fact that the electrodes are integrated into the glazed surface at the surface outside of the windscreen subjected to the ambient air of the vehicle, or else they are installed in one or more separate components at a distance close to the glazed surface, that is to say a distance of the order of t to 5 centimeters.

It should be understood that, in the detection device according to the invention, the first and the second electrode are in contact with the ambient air and that the measurement of electrical quantity in the detection zone between them is impacted by the resistance of the medium. in which they are arranged.

It should be noted that the determined electrical quantity, for example the resistivity or the electrical conductivity, varies according to whether the ambient environment is air, ice, snow or water. According to the present invention, the electrodes are dimensioned to make it possible to detect the variation of an electrical quantity specific to the presence of snow.

In this context of variable electrical quantities as a function of the composition of the ambient medium, it is worth noting the specificity of snow which has a variable resistivity as a function of the thickness of the snow layer. Therefore, it is advantageous to provide for comparing the value of the electrical quantity with representative thresholds of different thicknesses.

The type of detection by comparison of an electrical quantity between two electrodes with respect to threshold values thus makes it possible to separate the electrodes from one another and to avoid that a detection surface is penalizing for the visibility of the driver. According to a characteristic of the invention, the two electrodes are separated by at least one centimeter. According to the application cases which will be described below, these electrodes can be separated by around five centimeters, by being carried on the same component, or else be separated by several tens of centimeters, over a large glazed area. windshield type.

According to various characteristics of the invention, the measurement of the electrical quantity considered can be carried out at previously defined time intervals, or it can be controlled by a control unit of such a vehicle as soon as a parameter representative of the meteorology, for example an outside temperature, crosses a previously defined threshold value. According to a characteristic of the invention, the measuring member is configured to measure the electrical conductivity of the detection zone between the first electrode and the second electrode.

According to a characteristic of the invention, the detection device according to the invention can be electrically powered by a vehicle battery.

According to a first series of characteristics of the invention, taken alone or in combination, it can be provided that:

- At least one of the previously defined electrodes is arranged on the glass surface on which the detection is carried out. Advantageously, the two electrodes are arranged on this glazed surface. For example, the two electrodes can be included in a sheet of transparent or translucent material attached to the glass surface.

the glazed surface on which the snow detection is carried out is a windshield of a motor vehicle, and the electrodes are arranged in the lower part of such a windshield. The lower part here designates the part of the windscreen closest to the ground on which the vehicle in question is placed, with reference to a vertical direction of the vehicle. It is therefore a region in which the snow will accumulate preferentially, in particular by sliding by gravity on the glazed, inclined surface of the windshield.

- The two electrodes can be arranged along an edge of such a windshield, and the distance separating them can range from a few millimeters to a few tens of centimeters. In particular, they may be arranged along a transverse edge, an edge of the windshield parallel to a transverse direction of the vehicle and located near the top of the vehicle (that is to say close to the roof of said vehicle) or close to the bottom of the vehicle (i.e. close to the ground on which the vehicle is placed).

According to other characteristics of the invention, taken alone or in combination, provision can be made for at least one of the electrodes to be arranged on a wiper blade of the glass surface on which the snow detection is carried out, and that in this context:

- The two electrodes are arranged on such a wiper blade. - At least one of the electrodes of the device according to the invention is arranged on the connection assembly by which the wiper blade, formed of the wiper blade and its support structure, is attached to the drive arm , or at least one of the aforementioned electrodes is arranged on an end piece as mentioned above.

- The first electrode and the second electrode are arranged on the same side of the wiper blade with respect to a median longitudinal axis of extension of the wiper blade formed by the wiper blade and its supporting structure. The term “median longitudinal axis” is understood here to mean an axis parallel to the longitudinal direction, previously defined, of the wiper blade, and passing through the middle of the wiper blade and of its supporting structure in the transverse direction, previously defined, wiper blade.

More precisely still, when the two previously defined electrodes are arranged on a wiper blade of a vehicle, the invention provides that these two electrodes are placed, relatively to the glazed surface against which the wiper blade is placed on the side of the wiper blade intended to be oriented towards the region of this glazed surface in which snow is likely to accumulate most quickly. For example, in the case where the glazed surface on which the detection is carried out is a windshield of a motor vehicle, the electrodes will advantageously be arranged on the side of a wiper blade intended to be oriented towards the part high of the windscreen, with reference to the vertical direction, previously mentioned, of the vehicle. Indeed, such a windshield having an inclined surface, the snow will accumulate in the first place, in particular by gravity, in the region located between the glass surface and the side of the wiping blade, pressed against the aforementioned glass surface. , oriented towards the upper part of the windscreen.

According to another series of characteristics, taken separately or in combination:

- the central processing unit is configured to compare a value of the electrical quantity measured by the measuring device with at least a predefined threshold value, and to control a vehicle wiper assembly as a function of the result of this comparison. The wiper assembly may here include, in addition to a wiper blade as mentioned above, a drive arm drive motor and a control assembly of such a drive motor. Let us recall here that the object of the invention is to detect snow present on a glass surface in order to prevent its accumulation on this glass surface. The central unit is therefore configured to, as soon as a quantity of snow is detected, to control the evacuation of the glazed surface. This evacuation is advantageously carried out by one or more operations for wiping the glass surface under consideration, that is to say by triggering one or more back and forth movements of the wiper blade against the glass surface, by starting the corresponding drive motor.

the threshold value can be defined experimentally, for example by calibrating the detection device according to the invention.

- the snow removal operation by wiping the glass surface can be controlled as soon as the value of the electrical quantity measured is greater than the aforementioned threshold value. For example, in the case where the electrical quantity measured is an electrical conductivity between the first electrode and the second electrode, the wiping operation of the glazed surface can be controlled as soon as the measured electrical conductivity is greater than or equal to 1st ⁸ iî m (ohms-meter), value representative of a layer of thickness of one centimeter.

the central unit can be configured to control a wiping operation on the glazed surface as soon as a variation in the electrical quantity measured is greater than a previously defined threshold variation. In other words, according to this other exemplary embodiment, the central unit is configured to calculate, from different values, measured by the measuring member of the detection device, a variation of the electrical quantity chosen, and for compare this variation to a previously defined threshold variation. This allows, in particular, to take into account an initial state of the glazed surface in which a small residual amount of snow would be present, insufficient to be detected as such, but sufficient for the value of the quantity electrical measured is different from an initial value when the glass surface is, for example, completely dry.

- the central unit is configured to prevent the use or stop of a vehicle wiping assembly as soon as the value of the chosen electrical quantity, measured by the measuring device of the detection device, is greater than a second threshold value, previously defined. This allows, for example in the event of heavy snowfall, to avoid any damage to the wiper assembly by overheating of its drive motor.

As it has just been described, the invention makes it possible, with simple and inexpensive means, to carry out a reliable detection of the snow accumulated or being accumulated on a glass surface. The invention thus achieves the goal it set for itself.

The invention also extends to a method of detecting snow on a glazed surface of a motor vehicle, comprising at least:

a first step of measuring an electrical quantity between a first electrode and a second electrode of a snow detection device as just described,

a second step of comparing the measured value of the electrical quantity with at least a first predefined threshold value,

a third step of controlling a wiping operation of the glazed surface considered.

According to an example, a first threshold value and a second threshold value can be defined. The first threshold value is defined in relation to a minimum amount of snow from which a glass surface wiping operation is controlled, and the second threshold value is defined in relation to a maximum amount of snow above which a wiping operation of the glass surface in question is stopped and / or is not started so as not to damage the wiper assembly of the vehicle. By way of nonlimiting example, in the case where the electrical quantity measured is an electrical conductivity between the two previously defined electrodes, the first threshold value may be of the order of 1 ⁸ Ohm-m, value representative of a layer snow of the order of t centimeter and the second threshold value may be of the order of io-s Ohm m, value representative of a layer of snow of the order of 10 centimeters.

It should be noted that the wiping operation of the glazed surface controlled as part of the third step of the method according to the invention may include one or more consecutive back and forth movements of a wiping brush on the glass surface considered. Furthermore, according to an advantageous variant, a wiping operation can be simultaneously controlled on the glazed surface in the vicinity of which the electrodes of the detection device according to the invention are placed, as well as on other glazed surfaces of the vehicle such as , for example, glazed surfaces of optical lighting and / or signaling devices or optical devices for assisting in driving the vehicle in question.

The invention also advantageously provides that, during the wiping operation of the glazed surface, the previously defined electrodes are also cleaned so that the value of the electrical quantity measured between them returns to its initial value or to a value close to this, before snow is present. In the case where the electrodes are arranged on the glass surface on which the snow detection is carried out, they are therefore advantageously placed on the path of at least one wiper blade of this surface. In the case where the aforementioned electrodes are arranged on a wiper blade, the invention may, for example, provide that the electrodes are arranged in such a way that the snow will be automatically evacuated therefrom by the back-and-forth movement. comes from the wiper blade, or, according to one example, a slight electric current could be generated between the two electrodes in order to evacuate the snow by the Joule effect.

According to an advantageous variant, the method according to the invention comprises a preliminary step of measuring an outside ambient temperature and of comparing this outside ambient temperature with a previously defined threshold value. Such a step makes it possible to reduce the energy expenditure induced by the detection device and the method according to the invention, by limiting the use of the detection device and the implementation of the method according to the invention to the circumstances in which a drop in snow is possible from a meteorological point of view. By way of nonlimiting example, the implementation of the first step of the method according to the invention, previously defined, could be conditioned by an ambient temperature value less than a few degrees Celsius, for example less than 4 or 5 degrees Celsius.

The invention finally extends to a motor vehicle comprising at least one snow detection device as described above. According to an example, the glass surface of such a vehicle in the vicinity of which the first electrode and the second electrode previously defined are placed is a vehicle windshield. The invention also extends to such a vehicle comprising a central unit configured to implement a method as previously described.

It should be noted that, according to an advantageous example, several pairs of electrodes as defined above can be, without harming the invention, arranged in the vicinity of different glass surfaces of such a vehicle, and that for example all these electrodes can be connected to a common control unit as previously mentioned. The invention can then provide that the values of the chosen electrical quantity, measured between the different pairs of electrodes, are compared with each other and with the threshold value (s) previously defined, thus increasing the sensitivity and the precision of the detection carried out.

Other characteristics, details and advantages of the invention will appear more clearly with the aid of the following description and the drawings, among which:

- Figure 1 is a general schematic view of a motor vehicle equipped with a snow detection device according to the invention, in which the electrodes of this detection device are arranged on a windshield of the vehicle, in a part lower windshield,

- Figure 2 is a schematic view of a vehicle windshield illustrating a variant of the embodiment illustrated in Figure 1, in which the electrodes are this time arranged in an upper part of the windshield,

FIG. 3 schematically illustrates a particular arrangement of the elements of the detection device according to the invention for implementing a method according to the invention, Figure 4 is a schematic view of the different steps of a method according to the invention, Figure 5 is a schematic perspective view of a wiper blade of a motor vehicle, capable of being fitted with a snow detection device, FIG. 6 is a schematic perspective view of a detail of a wiper blade such as that represented by FIG. 5, in which the electrodes of the detection device according to the invention are arranged on a connection assembly of the wiper blade, FIG. 7 is a schematic perspective view of a detail of a wiper blade such as that represented by FIG. 5, in which the electrodes of the detection device according to the invention are arranged on an end piece of the wiper blade, FIG. 8 is a schematic sectional view illustrating an arrangement of the electrodes of a snow detection device according to the invention on a wiper blade by relative to a glazed surface against which the wiper blade is placed,

It should first be noted that if the figures show the invention in detail for its implementation, they can of course be used to better define the invention if necessary. It should also be noted that, in all of the figures, similar elements and / or fulfilling the same function are indicated by the same reference.

Figure t is a general perspective view of a motor vehicle 500 equipped with a snow detection device 100 according to the invention. With reference to this figure, a trihedron (L, T, V) is defined representing the directions, respectively, longitudinal L, transverse T, and vertical V, of the vehicle. With reference to these different directions, the term "top" designates the parts of the vehicle 500 located closest to the roof 510 of the latter in the vertical direction V previously defined, and the term "bottom" designates the parts of the vehicle 500 located the closer to a chassis 520 of the latter according to the direction vertical V above. In other words, the designation "low" designates the elements of the vehicle 500 located closest to the ground on which said vehicle 500 is placed, and the designation "high" designates the elements of the vehicle 500 most distant from the ground on which said vehicle 500 is placed.

The snow detection device 100 comprises a first electrode 1 and a second electrode 2, each arranged in the vicinity of the windshield, as well as a measurement member 3 schematically mentioned in FIG. 1.

According to the particularly advantageous, but not exclusive, exemplary embodiment illustrated in FIG. 1, the first electrode 1 and the second electrode 2 are arranged in a lower part of the windshield 400, in the vicinity of the two wiper blades. 4 when these are in their rest position. In this context, the first electrode 1 and the second electrode 2 can be arranged on the exterior surface of the windshield 400 of the vehicle 500, or else be embedded in the thickness of the windshield as soon as they are flush with this surface. outside, exposed to ambient air outside the vehicle 500 and therefore exposed to the possible presence of snow.

It should be noted that the illustration in FIG. 1 also applies to an integration of each of the two electrodes respectively in a nozzle for windshield cleaning fluid, arranged on an edge of the windshield.

Whatever the embodiment, it is preferable that the electrodes 1, 2 are arranged one and the other at equal distance from the external surface of the windshield, which is obvious when the two electrodes are arranged on the surface. of the windshield and this must also be the case when the electrodes are arranged at a distance on separate nozzles.

With reference to FIG. 1, the electrodes 1, 2 are placed near a low edge 420 of the windshield 400 substantially parallel to the transverse direction T previously defined, and their spacing 450, measured substantially parallel to the transverse direction T above, is substantially equal to the distance separating, in this same transverse direction T, the axis of rotation of the drive arms 45 of the two wiper blades 4 shown in Figures 1 and 2. The distance 450 above may be of the order of a few centimeters to several tens of centimeters depending on the size of the windshield 400. According to a variant schematically represented in FIG. 2, the electrodes i, 2 can be arranged near a high transverse edge 430 of the windshield 400.

In the example described above of electrodes arranged on or in the windshield, these electrodes 1, 2 are advantageously arranged on the windshield 400 in such a way that, during the angular reciprocating movements of the brushes d 'wiper 4 on the windshield 400, they are located in a surface 460 swept by a wiper blade of the wiper blades 4.

In the example described above of electrodes arranged on or in the windshield, the electrodes 1, 2 can be inserted in a transparent film attached, for example by gluing, on the windshield 400. Consequently, and whatever either the area in which the electrodes are installed, they should not be in the driver's field of vision, or at the very least they will impair the visibility of the driver as little as possible, it being understood that even if the electrodes are made of a substantially transparent or translucent material, they can remain visible to the conductor. Examples of embodiments will be described below in which the electrodes are embedded on components already present in the driver's field of vision so as not to impose additional potential discomfort, as may have been already mentioned for implantation in cleaning fluid jets.

The measuring member 3 is configured to measure an electrical quantity 300 between the first electrode 1 and the second electrode 2. According to the invention, the electrical quantity 300 measured is chosen for its sensitivity to the presence of snow on the windshield 400 or, more generally, on the glass surface on which the snow detection is carried out. In other words, the electrical quantity 300 measured by the measuring member 3 is chosen in such a way that the presence of a small amount of snow causes a measurable variation of this electrical quantity 300. According to one example, the electrical quantity 300 measured by the measuring member 3 is an electrical conductivity of a detection volume 700, as will be described below, comprised between the first electrode 1 and the second electrode 2. According to the embodiment illustrated by FIGS. T and 2, in which the electrodes t, 2, are placed on a windshield 400, the detection volume 700 consists of the external surface 410 of the windshield 400 and d an outside air gap situated in contact with the above-mentioned outer surface 410, between the electrodes 1, 2, of the detection device 100. When snow is deposited on the outer surface 410 of the windshield 400, the electrical conductivity of the air space situated in contact with this external surface varies significantly, thus allowing the desired detection.

By way of nonlimiting examples, the electrical conductivity of the detection volume 700 comprised between the first electrode 1 and the second electrode 2 when a layer of snow about one centimeter thick is present on the outer surface 410 of the barrier. breeze 400 is of the order of 1 ⁸ Wm (ohms-meter), and this same electrical conductivity has a value of the order of 10-5 iî m when the thickness of this layer of snow is of the order about ten centimeters on the outer surface 410 of the windshield 400. An electrical quantity 300 such as the electrical conductivity therefore allows detection with a high sensitivity of a layer of snow being accumulated on the windshield 400 .

FIG. 4 illustrates more particularly the means used to control and to communicate with the electrodes of the detection device.

According to the invention, the detection device 100 comprises, in addition to the electrodes and the measurement member mentioned above, a central unit 5 comprising at least one control module 50 for the measurement member, an acquisition and data processing 52 to deduce therefrom information on the presence of snow and a control module 54 to generate a control instruction for a wiping system.

The control module 50 is configured to determine whether these conditions for implementing the measuring member are met, in particular in order to avoid measurements being carried out when it is certain that the glazed surface is not covered of snow. By way of nonlimiting example, the control module receives outside temperature information measured by a temperature sensor 51 of the vehicle. Such a configuration makes it possible, in particular, to reduce the energy expenditure of the detection device too, by stopping the operation of the detection device during meteorological conditions in which snowfall is excluded.

The data acquisition and processing module 52 is configured to recover on the one hand, by appropriate communication means, wired or wireless depending on the variants, at least one value 310 of the electrical quantity 300, measured by the measuring member 3, and on the other hand compare this value 310 of the electrical quantity 300 with at least a first predefined threshold value 350, as illustrated by the operating process diagram in FIG. 5. For example, the first threshold value 350 can be defined as being the value of the electrical conductivity 300 of the ambient air when a layer of snow of the order of a few millimeters to one centimeter is present on the outer surface 410 of the windshield 400 .

More generally, the first threshold value 350 is defined as being the value of the electrical quantity 300 for a minimum thickness of snow on the windshield 400 or, more generally, on a glazed surface of the vehicle 500, minimum thickness beyond which the presence of snow on the aforementioned glazed surface 400 may impair visibility for the driver and / or for the passengers of the vehicle 500, or may impair the operation or the performance of an optical element having a glazed surface 400 as mentioned above.

Alternatively or cumulatively, the data acquisition and processing module 52 can recover or be implemented with a second threshold value 360, previously defined, and this data acquisition and module is configured to compare the value 310 of the electrical quantity 300, measured by the measuring member 3, with this second threshold value 360. Advantageously, the second threshold value 360 is defined as being the value of the electrical quantity 300 for a maximum thickness of snow on the windshield 400 or, more generally, on a glazed surface 400 of the vehicle 500, maximum thickness beyond which a wiping operation, by one or more wiper blades 4, of the snow present on the glazed surface 400, could damage the drive system of the wiper blade (s) 4, for example by overheating of the drive motor 6 of such brushes, shown schematically in FIG. 4. For example, the second threshold value 360 can be defined as being the value of the electrical conductivity 300 when a layer of snow about ten centimeters thick is present on the glass surface 400.

The control module 54 is configured to generate an instruction for controlling the wiper blades 4 as a function of the result of the comparisons of the value of electrical quantity with respect to the different thresholds chosen. A first level of control results in actuation or stopping of the wiping system, that is to say of the drive motor or motors 6 of the wiper blades 4 according to the absence of snow or the amount of snow detected. A second level of control can consist in the modulation over time of the control instruction, for example the determination of the number of successive movements of angular back and forth of one or more wiper blades 4 on the exterior surface 410 of the windshield 400 as a function of the thickness E of snow, it being understood that the data acquisition and processing module and the control module can correlate the measured value with an estimated thickness of snow.

Both the measuring device 3, the drive motor 6 and the central unit 5 can be electrically powered by a battery 530 of the vehicle 500, so that the detection system according to the invention is capable of operating at stopping the vehicle. Such a configuration also makes it possible, for example, to trigger a detection of snow when the vehicle is not occupied, for example before the vehicle is used in the morning. In this case, the control module 50 can be configured to start the ignition, if the temperature conditions are met, at one or more hours predefined by a user, before using the vehicle. This is of particular interest for example for vehicles located in regions in which snowfall can frequently occur during the night. In this case, in particular by configuring the control module so that it proceeds with such an implementation of the measurement member at time intervals of a few hours, the detection device 100 according to the invention and the associated method avoid excessive accumulation of snow on one or more several glass surfaces 400 of the vehicle during the night, thus reducing, for the user, the duration of any snow removal before use of the vehicle.

FIG. 4 schematically presents the different steps of a method according to the invention.

As previously described, the method according to the invention comprises a first step Si during which the measuring member 3 of the detection device 100, as previously described and illustrated, performs a measurement of an electrical quantity 300.

During a second step S2 of the method according to the invention, the value 310 of the electrical quantity 300 measured by the measuring member 3 is recovered by the data acquisition and processing module 52, and this module data acquisition and processing also recovers the first threshold value 350 and the second threshold value 360.

During a third step S3 of the method according to the invention, the data acquisition and processing module 52 compares the value 310 of the electrical quantity 300 acquired beforehand with a first threshold value 350. If the result of the comparison is such that the acquired value 310 is less than the first threshold value (310 <350), then no action is carried out and the loop ends, starting again towards a measurement step.

If the result of the comparison is such that the value 310 acquired is greater than the first threshold value (310> 350), it is determined that the amount of snow is sufficient to impair the visibility of the driver or to interfere with the detection of the sensors behind the glass surface and that the process must proceed to the next step.

During a third step S4, which is optional but which has the advantages described above, the value 310 acquired is compared with the second threshold value 360, in order to determine whether the amount of snow is not too large to authorize an operation of wiping by the wiping system without risk of system overheating. If the result of the comparison is such that the value acquired 310 is less than the second threshold value (310 <360), then the module of control is implemented in a fifth step S5 to generate a command for controlling the vehicle's wiping system. Simultaneously, the process can be restarted to determine whether the layer of snow remaining after the wiping operation should be considered or not. Furthermore, in the fourth step, if the result of the comparison is such that the value acquired 310 is greater than the second threshold value (310> 360), then no action is carried out and the loop ends, starting again towards a measurement step.

The process can be carried out in a loop for a determined period or at the end of a determined number of cycles. Alternatively, it may also be decided to end the process as soon as a wiping operation is controlled by the control module 52.

In the example illustrated in FIG. 4, a preliminary step Sp has been envisaged, carried out before the first step Si previously described. The preliminary step is implemented by the control module 50 and consists in recovering outside temperature information 600, if necessary by controlling an outside temperature measurement by a vehicle measurement device. The control module 50 is configured to compare, during this preliminary Sp, the measured value of the temperature 600 with a third threshold value 650 previously defined and for, depending on the result of this comparison, to control or not the realization of the first step If previously described. According to one example, the first step Si of the method according to the invention will be controlled as soon as the outside temperature 600 is less than a threshold value 650 of the order of a few degrees Celsius, for example 4 to 5 degrees Celsius.

We will now describe a second embodiment, with reference to FIGS. 5 to 7, according to which the snow detection device is configured with at least one electrode secured to a wiper blade 4 as shown in the figure 5.

It should be noted that the principle of the invention according to which a quantity of snow is detected as a function of the comparison of an electric magnitude value measured between the electrodes remains the same depending on whether the electrodes on board the windshield or on the wiper blade. One could envisage that one of the electrodes is placed on the windshield and that the other is on board the wiper blade without this changing the principle of the invention. However, in this case it should be ensured that the measurement is carried out when the spacing between the electrodes is known, for example when the brush equipped with the electrode is in its rest position.

In what follows, we will describe an advantageous embodiment in which the two electrodes are mounted on the same wiper blade, without this being limiting of this second embodiment.

As shown in FIG. 5, a wiper blade 4 comprises in particular a scraper blade 41, also designated as a wiper blade, received in a support structure 40. The wiper blade 41 and its support structure 40 all have two an elongated shape in a common direction, designated in the following as the longitudinal direction L of the wiper blade 4. Advantageously, at each of their ends in the longitudinal direction L above, the wiping blade 41 and its structure carrier are equipped with an end piece 43. Each end piece 43 is configured to receive both a longitudinal end of the support structure 40 and a longitudinal end of the wiper blade 41. Each end piece 43 therefore ensures the maintenance in particular of the carrying structure 40 and the wiping blade 41 at the longitudinal ends thereof.

The wiper blade 4 also comprises a drive arm 45, diagrammatically shown in FIG. 5, and an assembly 42 for connecting this drive arm 45 to the assembly formed by the wiper blade 41 and its support structure 40. In a wiper assembly of a motor vehicle 500, the drive arm 45 is controlled to perform an angular back-and-forth movement above the glass surface 400 to be wiped / cleaned. In this angular back-and-forth movement of the drive arm 45, the support structure 40 and the scraper blade 41 are pressed and driven in an angular movement against the glass surface 400 to carry out the desired wiping / cleaning operation. . With reference to FIG. 5, the common direction of the width of the wiper blade 41 and of its support structure 40, perpendicular to the abovementioned longitudinal direction L, is defined as transverse direction T of the wiper blade 4. The longitudinal direction L and the transverse direction T together define a wiping plane in which the wiping blade 41 and its support structure 40 are driven by the angular reciprocating movement of the drive arm 45. In with reference to the longitudinal direction L and to the aforementioned transverse direction T, a vertical direction V of the wiper blade 4 is defined, perpendicular both to the longitudinal direction L and to the transverse direction T, so that the directions L, V, T together form a direct trihedron, visible in Figures 5 to 8.

Also shown in FIG. 5 is a median longitudinal axis X of the wiper blade 4, parallel to the longitudinal direction L and passing substantially through the middle of the support structure 40 and of the wiper blade 41 in the transverse direction. T previously defined.

Figures 6 and 7 each illustrate an exemplary embodiment of the detection device 100 according to the invention, in which the first electrode 1 and the second electrode 2 are arranged on a wiper blade 4 such as that illustrated in the figure 4.

With reference to FIG. 6, the first electrode 1 and the second electrode 2 are arranged on the connection assembly 42 previously defined, while with reference to FIG. 7, the first electrode 1 and the second electrode 2 are arranged on an end fitting 43, previously defined, of the wiper blade 4. It should be noted that, according to these two embodiments, the distance 450 between the first electrode 1 and the second electrode 2 may be 1 'order of a few millimeters to a few centimeters, while this same spacing 450 was greater, if necessary of the order of a meter, according to the first embodiment of the invention illustrated in Figures 1 and 2. The invention therefore offers a wide variety of installation of the electrodes of the snow detection device 100, allowing the installation of the electrodes 1, 2, of the latter, on a large variety of glass surfaces 400 of a vehicle 500, whatever their size and destination.

The fact that the electrodes are made integral with the connection assembly 42 or an end piece 43 has the same advantage of having electrodes integral with an element attached to the wiping brush. In this way, the electrodes can be easily attached to the brush as an aftermarket, that is to say on the market for spare parts, without being provided on the original wiping brushes, by changing only plastic parts that can be easily assembled and disassembled in relation to the supporting structure of the wiper blade.

The second embodiment differs from the first embodiment mainly due to the position of the electrodes on the wiper blade rather than on a glass surface. It should be noted that in this second embodiment, the measuring member can be on board the brush, and it is then necessary to provide means of communication between the measuring member and the central unit 5 to transmit the value 310 of electrical quantity measured 300.

Due to their incorporation in the wiper blade, the electrodes do not present any additional potential inconvenience to the driver. As illustrated, they can then have a substantial thickness as long as they remain within the volume defined by the wiper blade and thus have sufficient capacity to detect the variations in resistivity of the ambient air specific to the presence of snow.

It should also be noted that, according to the two embodiments illustrated by FIGS. 6 and 7, the electrodes 1, 2, are aligned in a direction substantially parallel to the longitudinal direction L of the wiper blade 4. This configuration allows sufficient spacing between the two electrodes without the space between the two electrodes where the detection of the resistivity of the ambient air is crossed by the scraper blade of the brush. It follows from this arrangement that the two electrodes are arranged on the same side of the brush, relative to the median longitudinal axis X of the brush and in the transverse direction T of the brush. FIG. 8 illustrates, in section along a vertical transverse plane substantially parallel to the transverse direction T and to the vertical direction V, a wiper blade 4 equipped with the electrodes t, 2, of the detection device too according to the invention , and a glass surface 400 against which the wiper blade 4 is placed.

Found in Figure 8, schematically shown, the connection assembly 42, the support structure 40 and the wiper blade 41 previously defined. Also found, schematically shown, the first electrode 1 and the second electrode 2 of the snow detection device 100 according to the invention. The longitudinal arrangement of the two electrodes here allows only the closest electrode to be seen.

As may have been specified previously, the first electrode 1 and the second electrode 2 are arranged on the same side of the wiper blade 4 with respect to the median longitudinal axis X, in the transverse direction T of the blade . More specifically, the first electrode 1 and the second electrode 2 are arranged on the same side of a median vertical longitudinal plane P containing the median longitudinal axis X previously defined.

Advantageously, the invention provides that the first electrode 1 and the second electrode 2 are arranged, with respect to the above-mentioned median vertical longitudinal plane P, on the side of the wiper blade 4 oriented towards the upper part of the glass surface 400, with reference to the names previously defined.

Such a configuration makes it possible in particular to consider the accumulation of snow against the brush and to facilitate the detection of the modification of the electrical quantity measured due to this greater depth of snow. The measurement of the electrical quantity is done when the vehicle is stopped, with the wiper blades in the rest position, conventionally in the lower part of the windshield. Snow coming by gravity against the wiper blade tends to accumulate and the level of snow in this area just above the blade is therefore higher than on the rest of the windshield. The electrodes being arranged at a distance from the surface of the windshield, it is advantageous here to ensure that they are turned towards the upper part so that the accumulation of snow makes it possible to quickly reach the electrodes and that the snow detection information, because the resistivity of the ambient air between the electrodes is disturbed, or taken into account as soon as possible. The detection of this snow can therefore be carried out early by the too detection device according to the invention, and, therefore, the snow can be removed more quickly from the glazed surface 400 considered.

The invention, as just described and illustrated, allows, by the implementation of simple and inexpensive means, to carry out an effective and reliable detection of the presence of snow during accumulation or already accumulated. on one or more glass surfaces of a motor vehicle. By the simplicity of the means which it implements, the invention makes it possible, by means of centralized detection within the vehicle in question, to simultaneously remove the snow present on several glazed surfaces of the vehicle. By the low cost of the means which it implements, the invention makes it possible, by the installation of pairs of electrodes as previously described, to carry out the detection of snow at different points of the vehicle, thus increasing the precision of the detection carried out. Finally, the invention offers the possibility of detection when the vehicle is not in use, thus making it possible to reduce possible snow removal times for one or more glazed surfaces of the vehicle before use of the latter.

The invention cannot however be limited to the means and configurations described and illustrated, and it also applies to all means or equivalent configurations and to any combination of such means. In particular, if the invention has been described and illustrated here preferentially in its application to a windshield of a vehicle, it applies to any glazed surface of such a vehicle, in particular to glazed surfaces and / or to lenses of optical driving assistance and / or parking assistance devices such as, by way of nonlimiting examples, reversing cameras, lighting and / or signaling systems, etc.

In addition, if the invention has been described and illustrated here according to embodiments in which the electrodes of the detection device are placed in the vicinity of the glass surface on which the detection is carried out, it is clear from the above that such electrodes can be installed in any region of a motor vehicle, provided that it is possible to measure, in a detection zone which they help to delimit, an electrical quantity whose value is modified by the presence of snow, and insofar as the detection of snow snow between these electrodes generates a wiping operation one or more glass surfaces of the vehicle as described in this document.

Claims

1. Device (ioo) for detecting snow on a glazed surface (400) of a motor vehicle (500), characterized in that it comprises at least a first electrode (1) and a second electrode (2) arranged at distance from each other in the vicinity of the glass surface (400), a measuring member (3) configured to measure an electrical quantity (300) in a detection zone between the first electrode (1) and the second electrode (2), and at least one central unit (5) configured to compare this measurement of the electrical quantity (300) with at least one threshold value (350, 360) representative of this electrical quantity for a given thickness (E) of snow on the glass surface (400) in the detection zone.

2. Device (100) according to the preceding claim, characterized in that at least one of the electrodes (1, 2) is arranged on the glass surface (400).

3. Device (100) according to any one of the preceding claims, characterized in that at least one of the electrodes (1, 2) is arranged on a wiper blade (4) of the glass surface (400 ).

4. Device (100) according to the preceding claim, characterized in that the first electrode (1) and the second electrode (2) are arranged on the same side of the wiper blade (4) relative to an axis longitudinal median elongation (X) of the wiper blade (4).

5. Device (100) according to any one of the preceding claims, characterized in that the central unit (5) is configured to on the one hand compare a value (310) of the electrical quantity (300) measured by the measuring member (3) with at least a first predefined threshold value (350) and, on the other hand, order a wiping operation of the glass surface (400) according to the result of this comparison.

6. Device (100) according to any one of the preceding claims, wherein the measuring member (3) is configured to measure the electrical conductivity of the detection area (700) between the first electrode (1) and the second electrode (2).

7. A method of detecting snow on a glazed surface (400) of a motor vehicle, comprising at least:

- a first step (Si) of measuring an electrical quantity (300) between a first electrode (1) and a second electrode (2) of a snow detection device (100) according to any one of the preceding claims ,

a second step (S2) of comparing the measured value (310) of the electrical quantity (300) with at least one predefined threshold value (350, 360),

- A third step (S3) for controlling a wiping operation on the glass surface (400).

8. Method according to the preceding claim, characterized in that it comprises a preliminary step (Sp) for measuring an outdoor ambient temperature (600).

9. Motor vehicle (500) comprising at least one snow detection device (100) according to any one of claims 1 to 6.

10. Vehicle (500) according to the preceding claim, characterized in that it comprises a central unit configured to implement a method according to any one of claims 7 and 8 on a glass surface (400) of the vehicle (500) .