FR3107969A1 - Protection device for a sensor / transmitter - Google Patents

Abstract

Device for protecting a sensor/transmitter The main object of the present invention is a device for protecting (4) a sensor/transmitter (3) of a vehicle (1), the protection device (4) comprising a motor electric motor (18) rotationally coupled to a protective casing (16) of the sensor/transmitter, the electric motor (18) being an electronically commutated motor comprising a stator (28) and a rotor (26) such that the stator (28 ) or the rotor (26) carries a winding (34, 35) comprising at least one coil and supplied with current via a sequence controlled by a control module (30), the control module (30) being configured to generate an instruction main control unit in which the supply of the winding (34) is controlled according to a main sequence defined to create a set of main magnetic fields able to drive the rotor (26) in rotation in a range of main rotation speeds, characterized in that that the control module (30) is not r further configured to issue a secondary control instruction in which the supply of the coil (34) is controlled according to at least one heating sequence distinct from said main sequence so as to generate a set of magnetic fields different from the set of main magnetic fields and configured to generate heating of the electric motor (18) leaving the rotor (26) immobile or rotating at a speed of a value lower than those of the main rotational speed range. Figure for abstract: Figure 2

Description

Sensor/transmitter protection device

The present invention relates to the field of driving assistance and in particular to driving assistance systems, comprising at least one sensor/transmitter, which can be installed on certain vehicles. More particularly, the invention relates to driving assistance systems comprising a device for protecting such a sensor/transmitter and an associated cleaning device.

Driver assistance systems include, for example, parking assistance systems and lane departure detection systems. In this context, sensors/transmitters are known to be installed on the exterior of vehicles in different places depending on the use made of them. The transmitter sensors can thus be found at the level of the rear or front bumper of the vehicle or even on the sides of the vehicle.

The sensor/transmitter, located outside the vehicle, is highly exposed to splashes of mineral or organic dirt which may be deposited on its transmission/reception surface. Especially in rainy weather, there are splashes of rain and dirt which can greatly affect the operability of the driving assistance system comprising such a sensor/transmitter. The emission/reception surfaces of the sensors/transmitters must therefore be protected and cleaned in order to guarantee their good operating condition, and this need is all the more important in the case of an autonomous vehicle, in which the piloting of the vehicle is carried out through the information collected by these sensors.

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

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

Another alternative provides for a sensor/transmitter, and for example a driving assistance system camera, to be associated with a protection device which comprises a rotating casing housing the sensor/transmitter by protecting it from the external environment. This association of a sensor/transmitter with a protective device is defined by the term sensing element. The rotating housing has a transparent cover element arranged opposite the lens of the sensor/transmitter to allow data acquisition. The rotating housing and the associated transparent cover element are driven in rotation by means of a motor forming part of the protection device. More particularly, the motor is configured to drive the rotation of the casing at a sufficient speed to remove by centrifugal effect any dirt or water that may be present on the transparent cover element. This centrifugal effect cleaning solution is significantly more effective than the vibration of the transparent cover element described above.

Such a cleaning system operating by centrifugal effect, that is to say comprising a rotating casing around the sensor/transmitter, involves difficulties in sealing the cavity in which the sensor/transmitter extends, both in relation to air than humidity.

Consequently, when the outside temperature of the vehicle and of the sensor/transmitter protection device becomes negative, during winter seasons for example, the water present in the protection device, for example in the form of humidity, can freeze on the protective device components as well as sensor/transmitter components. Frost can form at the level of the moving axes of the electric motor, or even between a moving element and a fixed element of the protection device and/or of the sensor/transmitter.

Furthermore, the detection assembly and its sensor/transmitter as they have just been described are placed in the vehicle in the vicinity of a bodywork part, and for example a grille, of a motor vehicle. In order to allow the acquisition of information by the sensor/transmitter, an opening is provided in the bodywork part and the transparent cover element, arranged at the front of the protective casing, is arranged at least partially in the opening, it being understood that the transparent cover element is arranged as far forward as possible to optimize the zones for transmitting and receiving the waves. It is understood that the transparent cover element being rotatable, an operating clearance is formed radially between this transparent element and the edge delimiting the opening which surrounds it. Again, in the event of intense cold, a layer of frost may form between the protective box and the edge delimiting the opening in the bodywork part, so that the protective box can be frozen in position.

When the layer of frost has a minimum thickness, it is possible to break this layer of frost by running the motor, for example at a higher speed than that intended for the cleaning operation. However, from a certain thickness and density of the layer of frost, the fact of using the motor to break the layer of frost may involve overheating of the motor and malfunctioning of the latter, without however being certain that the motor manages to rotate the protective casing.

It should be noted that in both cases, the operation of the electric motor generates an increase in temperature which can participate in removing at least part of the frost. But in the case of a heavy layer of frost, the part of the engine likely to be driven in rotation is blocked and prolonged starting of the engine may cause irreversible damage to this rotating part.

It is thus known to provide electric heating devices which can be powered on demand and in particular under very cold conditions, to ensure that the rotating parts comprising potentially frosted areas are free to rotate without blocking. Such an arrangement clutters the room, requiring the installation of additional means, and it is therefore sought alternative solutions that are less expensive and less penalizing for mounting the device.

In this context, the present invention proposes an alternative to existing solutions for defrosting sensor/transmitter protection devices, in particular by targeting the implementation of the electric motor associated with the protection device to heat at least part of the device without causing rotating its moving part.

The present invention firstly relates to a device for protecting a sensor/transmitter of a vehicle, the protection device comprising a protective casing configured to house the sensor/transmitter and mounted so as to move about an axis of rotation, a transparent cover element secured to the protective casing and configured to be disposed in the transmission/reception field of the sensor/transmitter, and an electric motor coupled to the protective casing to drive the protective casing and the transparent cover element, the electric motor being an electronically commutated motor comprising a stator and a rotor such that the stator or the rotor carries a winding comprising at least one coil and supplied with current via a sequence controlled by a control module and the rotor or the stator carries magnetic elements, the rotor being capable of rotating around or inside the stator under the effect of the movement of the elements m magnetic fields in rotating magnetic fields, the control module being configured to generate a main control instruction in which the supply of the winding is controlled according to a main sequence defined to create a set of main magnetic fields able to drive the rotor in rotation in a range of main rotational speeds, characterized in that the control module is also configured to issue a secondary control instruction in which the supply of the winding is controlled according to at least one heating sequence distinct from said main sequence of so as to generate a set of magnetic fields different from the set of main magnetic fields and configured to generate heating of the electric motor by leaving the rotor stationary or rotating at a speed of a value lower than those of the range of main rotational speeds .

In a main mode, that is to say when the control module generates a main control instruction, the rotation of the rotating part of the protection device, in other words the rotor, the protection box and the element transparent cover, is such that the rotating part is driven at high speeds, so as to be able to remove under the effect of centrifugal force the elements harmful to the acquisition of information by the sensor/transmitter which would be present on the surface of the transparent cover element.

The electric motor is arranged opposite the transparent cover element in the protective device, their arrangement being assessed with respect to the axis of rotation.

The electric motor consists of an electronically commutated motor, or brushless direct current motor (also known by the English name "brushless"). The rotor and the stator each carry electromagnetic elements whose interaction generates the movement of the rotor relative to the stator. The rotor and the stator are mounted independently of each other in said motor. The stator comprises a winding comprising at least one electromagnetic coil in which a switching of electric current, when it is carried out according to a defined order in a main operation, generates a rotating electromagnetic field. The rotor comprises permanent magnets whose presence in the electromagnetic field emitted by the wound stator causes the rotation of the rotor.

The power supply to the stator winding is controlled by the control module, issuing control instructions. The control module issues in particular the main control instruction to rotate the rotor around the axis of rotation in order to clean the transparent cover element of the protection device by centrifugation of dirt present on its surface.

According to the invention, the control module is also configured to issue at least one secondary control instruction thanks to which the stator of the electric motor generates a magnetic field which does not cause rotation, or at a low speed lower than the main rotation speed range, the rotor around the axis of rotation. The control instructions generated by the winding control module, and the resulting power supplies and switching, contribute to creating a temperature rise in the electric motor which is likely to propagate in the protective casing of the device according to the invention. Therefore, the invention makes it possible to create a rise in temperature likely to cause defrosting, while avoiding the rotation of the rotor of the electromagnetic motor at high speeds and therefore the risk of malfunction or breakage.

According to one characteristic of the invention, the winding comprises different phases, the main control instruction being such that the supply of the different phases of the winding is controlled according to a main sequence defined with a given order of supply of the phases and a given supply frequency range, the secondary control instruction being such that the heating sequence for supplying the different phases of the winding has a supply order different from the order of said defined sequence and/or a supply frequency distinct from the given supply frequency range.

According to an optional characteristic of the invention, the different phases of the winding are connected in star or in triangle.

According to an optional characteristic of the invention, a defined sequence of the secondary control instruction consists of an alternate supply between two phases of the winding. The alternation of the power supply is performed at a higher frequency than that of the main control instruction.

This alternating power supply, that is to say a power supply sequence in which the current flow is alternately carried out in one direction between a first phase and a second phase, then the current flow in a reverse direction between the second phase and the first phase, makes it possible to avoid producing a rotating field liable to drive the rotor in rotation, and therefore to lead to the heating of the electric motor without driving the rotor in rotation around the axis of rotation

Furthermore, according to an optional characteristic of the invention, the alternation of the supply of the secondary control instruction is carried out at a higher frequency than that of the main control instruction. For example, the alternating supply is carried out at a frequency of the order of 1kHz. In this way, the inertia of the rotating part prevents any micro-movement of the rotating part which could, in the event of a thick layer of frost, generate stresses on the rotating part, which even weak, contribute to damaging the engine.

By way of example, the winding comprising a first phase, a second phase and at least one other phase, the secondary control instruction generates an alternating supply of the phases such that the supply is made, if necessary very briefly, d a phase, for example the first phase, to another phase, for example the second phase, then, during the same period, in the opposite direction, here from the second phase to the first phase. However, the feeding period may differ, the feeding made from the first phase to the second phase may be longer than the feeding made from the second phase to the first phase, and vice versa when the feeding is alternated by being implemented first of all in a direction going from one phase to another then in the opposite direction.

In other words, it is understood that the supply of the winding according to the secondary control instruction consists in circulating an electric current from a first phase of the winding to a second phase of the winding, then in circulating an electric current in reverse direction from the second phase of the winding to the first phase of the winding without including the other phase of the winding.

According to another optional characteristic of the invention, the control module is configured to modify the secondary control instruction beyond a given period of time, said secondary control instruction being modified so as to generate an alternating supply of two other phases of the winding.

It should be understood that alternating power supply at high frequency between two phases, in one direction and then in the other, can lead to overheating of the winding at these two phases. The secondary control instruction is then able to generate a modification of the secondary control instruction so that this alternating power supply involves another phase, and if necessary one of the phases previously involved.

This modification of the secondary control instruction can be generated as soon as phase overheating is detected, but it is simpler and less expensive to theoretically define a given period of time after which it is estimated that a risk of overheating of one of the phases exists and it is therefore wise to let at least one of the phases rest. Again, such modification of the secondary instruction, and consequent modification of the phase supply, is advantageous at high frequency, so that the mass inertia of the parts forming the rotor prevents movement before the phase supply alternation is restored.

According to the invention, provision may be made for each phase of the winding to be supplied independently of each other, and the control module is in this case configured to generate a particular secondary control instruction in which a similar supply instruction for each winding phase is performed.

It is understood that each phase of the winding is independently connected to a power source, and that the current flowing in each phase is therefore independent of the current flowing in the other phases. Each phase can thus generate a magnetic field regardless of the magnetic fields generated by the other phases of the winding, all the phases of the winding being able to emit magnetic fields of the same orientation.

According to another optional characteristic of the invention, the secondary control instruction consists of supplying the phases of the winding one after the other in the order given by the main control instruction, at a frequency of lower value to that of the frequency of the main control instruction.

As mentioned, during the main operation of the electric motor, the supply of the various phases of the winding is carried out according to a given frequency range, extending from a minimum frequency to a maximum frequency, the maximum frequency allowing the rotating part to rotate fast enough, for example at about 10,000 rpm, for the centrifugal effect to clean the transparent cover element. In a main operating mode, the maximum frequency is reached gradually, by successive increases in frequency starting from the minimum frequency, to ensure that the rotating part is driven by considering the inertial forces.

According to the invention, the frequency of the power supply to the phases according to the heating sequence generated by this secondary control instruction is much lower than the minimum frequency value and remains lower than this minimum frequency value in order to ensure that the mass inertia of the rotor prevents the movement of the rotating part. The frequency of the power supply to the phases is not however zero, and in particular when the power supply to the phases is carried out in an alternating order, so that the rotor can vibrate and thus promote the breaking of the frost around it. .

According to an optional feature of the invention, the secondary control instruction generated by the control module is a pulse width modulated signal. The use of a pulse width modulation makes it possible, in particular for supply voltages of 12V, not to release too much heat and to be able to calibrate the release of heat according to the temperature and the quantity of frost to remove.

According to another optional feature of the invention, the control module is configured to generate the secondary control instruction when a driver switches on the ignition or starts the vehicle, and/or when the control module detects an abnormal resistance to drive rotating the rotor of the electric motor and/or when the temperature of the vehicle is at least below 2°C.

The secondary control instruction as it has been presented can be implemented in a preventive operation, upstream of the emission of the main control instruction. This makes it possible to ensure the defrosting of the electric motor before the rotation of the rotor by the wound stator in a main operating mode of the electric motor. This prevention is carried out when the driver of the vehicle equipped with the protective device according to the invention switches on the ignition or starts the vehicle, to prepare for the possible cleaning of the transparent cover element by centrifugal effect when the vehicle is moving.

Alternatively or additionally, the control module can generate the secondary control instruction when the rotation of the rotating part is blocked and information relating to this blockage, a measurement of torque or rotational speed for example, is received by the control module, but also when the ambient temperature or the temperature in the vicinity of the protection device is estimated to be low enough to present a risk of frost, and for example when the temperature in the vicinity of the protection device is below 2°C . It is understood that in the latter case, the protection device may include a temperature sensor.

The invention also relates to a method for de-icing the protection device according to one of the preceding characteristics, in which at least one step of de-icing the protection device is carried out during which a main control instruction of the main operation of the electric motor associated with the protection device into a secondary control instruction, by reducing the frequency of the motor winding supply switchings or by modifying the supply switching sequences so as to generate an alternating supply of two phases at high frequency.

The control module can in particular be configured to send at least two types of secondary control instruction one after the other. A first secondary control instruction consisting of supplying the phases one after the other at a frequency lower than that of the frequency range of the main operation is less brutal than a second secondary control instruction consisting of an alternating supply of two phases of the high-frequency winding, the control module is advantageously configured to issue the first secondary control instruction before the second secondary control instruction.

Thus, the control module only issues the second secondary control instruction when the first secondary control instruction is not sufficient to break the layer of frost blocking the protective device.

The invention also relates to a detection assembly comprising at least one sensor/transmitter and at least one protection device according to any one of the preceding characteristics.

Other characteristics, details and advantages of the invention will emerge more clearly on reading the description which follows on the one hand, and several examples of embodiment given by way of indication and not limitation with reference to the appended schematic drawings on the other. part, on which:

is a vehicle equipped with a protection device according to the invention;

is a longitudinal section of a protection device according to the invention and of a sensor/transmitter;

is a representation of a star-mounted three-phase winding capable of equipping the electric motor of the protection device represented in FIG. 2, according to a first step of a main mode of operation of the electric motor;

is a representation of a star-mounted three-phase winding capable of equipping the electric motor with the protection device represented in FIG. 2, according to a second stage of a main mode of operation of the electric motor;

is a representation of a star-connected three-phase winding capable of equipping the electric motor with the protection device represented in FIG. 2, according to a third stage of a main mode of operation of the electric motor;

is a representation of a star-mounted three-phase winding capable of equipping the electric motor of the protection device represented in FIG. 2, according to a fourth stage of a main mode of operation of the electric motor;

is a representation of a star-mounted three-phase winding capable of equipping the electric motor of the protection device represented in FIG. 2, according to a fifth step of a main mode of operation of the electric motor;

is a representation of a star-mounted three-phase winding capable of equipping the electric motor of the protection device represented in FIG. 2, according to a sixth step of a main mode of operation of the electric motor;

is a representation of a star-mounted three-phase winding capable of equipping the electric motor of the protection device shown in Figure 2, according to a first step of an operating mode of the electric motor aimed at defrosting the projection device by a alternation of phase supply;

is a representation of a star-mounted three-phase winding capable of equipping the electric motor of the protection device shown in Figure 2, according to a second step of an operating mode of the electric motor aimed at defrosting the projection device by a alternation of phase supply;

is a cross section of an electric motor of the protection device represented in FIG. 2 in which the electric current flows according to a supply of the phases of a winding one after the other at a frequency lower than the frequency range of the main operation of the electric motor; And

is a flowchart illustrating a method for defrosting the protection device according to one embodiment of the invention;

is a schematic representation of a single-phase electric motor capable of being supplied according to a heating sequence in accordance with the invention.

The features, variants and different embodiments of the invention may be associated with each other, in various combinations, insofar as they are not incompatible or exclusive with respect to each other. In particular, variants of the invention may be imagined comprising only a selection of characteristics described below in isolation from the other characteristics described, if this selection of characteristics is sufficient to confer a technical advantage and/or to differentiate the invention. compared to the prior art.

As a reminder, the invention relates to the field of protective devices for sensors/transmitters intended to equip vehicles and in particular motor vehicles and more particularly to devices capable of allowing cleaning by centrifugal effect of a transparent element arranged opposite the sensor/transmitter, the rotational drive of the transparent element being produced by an electric motor whose power supply is controlled by a control module. According to the invention, the control module is capable of generating a secondary control instruction intended to supply the electric motor in a way making it possible to provide controlled heating of the motor without however driving the rotating part of the protection device in rotation.

First of all with reference to FIG. 1, a vehicle 1 is equipped with a detection assembly 2 comprising at least one sensor/transmitter 3 and a protection device 4 according to the invention, the protection device 4 housing the sensor /transmitter 3 to ensure its protection. The detection assembly 2 is for example part of a vehicle driving assistance system 1.

In the example illustrated in FIG. 1, a detection assembly 2 has been more particularly illustrated arranged in the grille 5 of the vehicle 1, it being understood that such a detection assembly could also or alternatively be implemented at the rear of vehicle 1 or on its sides. The protection device 4 is in particular configured to be rotated at high speeds and to allow cleaning by centrifugal effect of a transparent cover element of the protection device 4 able to be placed facing the sensor/transmitter 3.

As illustrated in FIG. 2, the detection assembly 2, and in particular the sensor/transmitter 3 and the protection device 4 extend mainly longitudinally, around an axis of rotation A of a rotating part of the protective device. The protection device 4 defines a housing sized to receive the sensor/transmitter 3, it being understood that a part of the protection device is movable around the sensor/transmitter, the latter advantageously remaining fixed.

The sensor/transmitter 3 here has the form of a camera-type optical sensor 6, with an electronic box 8 and a sheath 10 housing power and communication cables. This sensor/transmitter 3 is mounted on a support member 12 participating in forming a fixed part of the protection device. It is understood that the camera 6 is the element of the sensor/transmitter 3 making it possible to acquire images of the road scene, which are then transmitted to the electronic unit 8 which houses electronic components not visible in all the figures. The electronic components of the electronic box 8 of the sensor/transmitter 3 ensure the management and processing of the images received by the optical camera 6 and the power supply and communication cables make it possible to ensure the transmission of the information acquired to the vehicle 1.

The protection device 4 comprises at least one transparent cover element 14, at least one casing 16 and at least one electric motor 18. The protection device 4 comprises in the example illustrated an intermediate element 20 connecting the casing 16 and the motor electric.

The housing 16 participates in defining the housing in which the sensor/transmitter is arranged, and this housing 16 is rotatably mounted around the axis of rotation A. It comprises a first end 15 and a second end 17 which are longitudinally opposite. The first end 15 is turned towards the road scene of which one wishes to acquire a representation via the sensor/transmitter and it carries the transparent cover element 14 while the second end 17 is integral with the electric motor 18, if necessary via the intermediate element 20.

The transparent cover element 14 is connected to the housing 16 in the vicinity of the first end 15, being arranged so as to be in the transmission/reception axis of the sensor/transmitter 3, coinciding with the axis of rotation A .

The electric motor 18 comprises a rotor 26 and a stator 28, both carrying electromagnetic components. The electric motor consists of an electronically commutated motor, or brushless direct current motor (also known by the English name “brushless”). The rotor 26 and the stator 28 each carry electromagnetic elements whose interaction generates the movement of the rotor relative to the stator. More particularly, the stator 28 comprises a winding comprising at least one electromagnetic coil in which a switching of the electric current supply, when it is carried out according to a defined order in a main operation, generates a rotating electromagnetic field. The rotor 26 comprises permanent magnets whose presence in the electromagnetic field emitted by the wound stator causes the rotation of the rotor. It should be noted that in the example illustrated in the figures and which will be described later, the stator 28 carries said winding and the rotor 26 carries permanent magnets but without this being limiting of the invention, since the winding power supply is controlled in accordance with the invention.

As illustrated in Figure 2, the electric motor 18 is an internal rotor motor, with the rotor 26 rotating inside the stator 28. It should be understood that the configuration of the electric motor is not here limiting of invention, and that it could alternatively have a rotor 26 positioned around the stator 28.

The stator 28, the support 12 and the sensor/transmitter 3 represent the fixed part of the protection device. The rotor 26, the housing 16, if necessary the intermediate element 20, and the transparent cover element 14 represent the mobile part of the protection device. The protection device 4 may in particular comprise at least one bearing 32, here a ball bearing, between the movable part and the fixed part, here between the intermediate element 20 and the support 12.

The power supply to the wound stator 28 is controlled by a control module 30 which is configured to issue control instructions corresponding to sequences of electrical signals which control the power supply to the stator 28 and more generally to the electric motor 18.

When the electric motor 18 is started, the control module 30 generates a main control instruction, an example of which will be described with more precision during the description of FIGS. 3 to 8 which follows, driving the rotor 26 in rotation. around the axis of rotation A. The rotor 26 drives the casing 16 and the transparent cover element 14 in rotation and the rotation of this transparent cover element 14 allows the dirt present on the cover element to be removed by centrifugal force. transparent cover 14, separating them outside the transmission/reception field of the sensor/transmitter 3.

In the example illustrated, the electric motor 18 is a polyphase motor, because one of the components of the motor, here the stator 28, is equipped with a winding, each phase of which is able to be supplied by an electric current to generate different magnetic fields in which the magnetic elements carried by the other component move. Furthermore, in the example illustrated, the winding 34 is a three-phase winding, with a first phase 36, a second phase 38 and a third phase 40, without this limiting the invention. In the following, we will speak of first phase 36, second phase 38 and at least one other phase 40.

Each phase 36, 38, 40 of the winding is connected at least one of its ends to a terminal for connection to an electrical network of the vehicle, switches represented schematically in FIG. 3 making it possible to activate or the electrical supply in the one of the stages. The current supply of each phase can therefore be carried out independently of each other, and for example with an electric current with a voltage of 12V. In a main mode, the control module controls the power supply to the phases by opening or closing such and such a switch so that the current flows in a given direction through such and such a phase.

The direction of current flow in the phases of the winding generates a particular orientation of the magnetic field created by the winding supplied with current, and the control module is configured to give a main control instruction in which the supply of the phases is determined in a given direction and at a given frequency so that the magnetic fields generated successively rotate the magnetic elements carried by the other component of the motor.

More particularly, each phase of the winding, when it is energized, creates a magnetic field which has a first pole and a second pole, each of the two poles corresponding to a phase being able to consist of a North pole N and a South pole S. known manner, the North pole N is designated as that corresponding to an orientation towards the periphery of the stator 28 of the magnetic field generated while the South pole S corresponds to an orientation towards the center of the stator 28 of the magnetic field generated. All the poles of the fields generated by the different phases 36, 38, 40 of the winding are distributed circumferentially in the stator 28 in a regular manner, the first pole corresponding to a phase being opposite to the second pole of this same phase with respect to the center of the stator 28.

The rotor 26 comprises a first magnetic element 42 and at least one second magnetic element 44, similar to a magnet. The first magnetic element 42 is polarized so as to be likened to a North pole magnet while the second magnetic element 44 is polarized so as to be likened to a South pole magnet. Depending on the North or South orientation given to the magnetic fields generated by the coil 34, the rotor 26 is caused to move in rotation by attraction and repulsion of its magnets.

According to the invention, as specified previously, the control module is configured to generate secondary control instructions in cases where a defrosting function is aimed, without the rotor rotating in or around the stator, that is to say without the generated magnetic field rotating the magnetic elements carried by the other component of the motor.

We will first describe the normal mode of operation, with a control module issuing a main control instruction, with reference to Figures 3 to 8, before describing different types of secondary control instructions according to the invention, with reference to Figures 9 to 11.

The following description relates to an assembly of the phases of the star winding, according to a known type of assembly in which each phase 36, 38, 40 is at one end connected to a current supply network 100 or to a ground 102 via a switch 36i, 38i, 40i, and at an opposite end to an interconnector 46 common to each of the phases. It should be understood that this type of assembly is not limiting and that the operation with a secondary control instruction as will be described below could be applied without departing from the context of the invention with a triangle assembly For example.

In the main operation of the electric motor 18, illustrated in FIGS. 3 to 8, the control module 30 sends a main control instruction to the winding of the stator 28 so that the different phases are successively supplied according to a main supply sequence, in a given order and at a given frequency.

As illustrated in Figure 3, the main control instruction generated by the control module 30 consists of a first step in the closing of the switch 36+ to connect the first end of the first phase to the power supply network current 100 and the closure of the switch 38- to connect the first end of the second phase to ground 102, all the other switches being open. The current thus flows from the first phase to the second phase, via the interconnector 46, and generates a magnetic field according to a first configuration.

As illustrated in Figure 4, in a second step, the main control instruction generated by the control module 30 consists of the closing of the switch 36+ to connect the first end of the first phase to the network of power supply 100 and the closing of switch 40- to connect the first end of the third phase to ground 102, all the other switches being open. The current thus flows from the first phase to the third phase, via the interconnector 46, and generates a magnetic field according to a second configuration. It should be noted that to pass from the first to the second stage, the switches associated with the first stage 36 remain in the same position.

As illustrated in Figure 5, in a third step, the main control instruction generated by the control module 30 consists of the closing of the switch 38+ to connect the first end of the second phase to the network of power supply 100 and the closing of switch 40- to connect the first end of the third phase to ground 102, all the other switches being open. The current thus flows from the second phase to the third phase, via the interconnector 46, and generates a magnetic field according to a third configuration. It should be noted that to pass from the second to the third stage, the switches associated with the third stage 40 remain in the same position.

As illustrated in FIG. 6, in a fourth step, the main control instruction generated by the control module 30 consists of the closing of the switch 38+ to connect the first end of the second phase to the network of power supply 100 and the closing of switch 36- to connect the first end of the first phase to ground 102, all the other switches being open. The current thus flows from the second phase to the first phase, via the interconnector 46, and generates a magnetic field according to a fourth configuration. It should be noted that to pass from the third to the fourth stage, the switches associated with the second stage 38 remain in the same position.

As illustrated in FIG. 7, in a fifth step, the main control instruction generated by the control module 30 consists of the closing of the switch 40+ to connect the first end of the third phase to the network of power supply 100 and the closing of switch 36- to connect the first end of the first phase to ground 102, all the other switches being open. The current thus flows from the third phase to the first phase, via the interconnector 46, and generates a magnetic field according to a fifth configuration. It should be noted that to pass from the fourth to the fifth stage, the switches associated with the first stage 36 remain in the same position.

As illustrated in Figure 8, in a sixth step of the main sequence, the main control instruction generated by the control module 30 consists of the closing of the switch 40+ to connect the first end of the third phase to the current supply network 100 and by closing switch 38- to connect the first end of the second phase to ground 102, all the other switches being open. The current thus flows from the third phase to the second phase, via the interconnector 46, and generates a magnetic field according to a sixth configuration. It should be noted that to pass from the fifth to the sixth stage, the switches associated with the third stage 40 remain in the same position.

According to this main control instruction, generating a main power supply sequence, a rotating magnetic field is thus produced allowing the rotation of the rotor. The frequency of passage from one state to another increases gradually from an excitation constant until the rotor reaches a rotational speed of approximately 10,000 revolutions per minute. “Excitation constant” means the minimum frequency of passage from one state to another of the different phases according to the main control instruction to drive the rotor in rotation when the latter is stationary.

However, when the external temperature of the vehicle 1 and thus of the optical device 2 is at least less than 2° C., or when a locking in rotation of the rotor is observed, or even at the request of the driver, the control module is able to generate a secondary control instruction to try to create a heating of the motor without however rotating the rotor, in order in particular to heat a possible layer of frost.

According to a first embodiment, more particularly illustrated in Figures 9 and 10, the secondary control instruction causes the defrosting of the protection device 4 by generating an alternating supply at high frequency between two phases of the winding 34.

More particularly, in the example illustrated, the secondary control instruction generates an alternating supply between the first phase 36 of the winding 34 and the second phase 38 of the winding 34 at high frequency.

In FIG. 9, there is illustrated a first step of this secondary control instruction which reproduces the first step of the main control instruction represented in FIG. 3. Thus, the secondary control instruction generated by the control module 30 consists first of all in the closing of switch 36+ to connect the first end of the first phase to the power supply network 100 and in the closing of switch 38- to connect the first end of the second phase to ground 102, all other switches being open. The current thus flows from the first phase to the second phase, via the interconnector 46, and generates a magnetic field according to a first configuration.

In FIG. 10, there is illustrated a following step of this secondary control instruction which aims to alternate the power supply described previously, this step corresponding to the fourth step of the main instruction illustrated in FIG. 6. Thus, the instruction secondary control generated by the control module 30 consists in a second step in the closing of the switch 38+ to connect the first end of the second phase to the current supply network 100 and in the closing of the switch 36 - To connect the first end of the first phase to ground 102, all the other switches being open. The current thus flows this time from the second phase to the first phase, via the interconnector 46, and generates a magnetic field according to a second configuration inverse to the first configuration of the previously generated magnetic field.

The alternation of supply of the first phase 36 and of the second phase 38 thus generates an alternation of two magnetic fields of opposite directions, which tends to maintain the permanent magnets associated with the rotor 26 in a fixed position, the inertia of the rotor on which these magnets are fixed preventing the assembly from rotating before the magnetic field is reversed. Indeed, it is notable in this embodiment that the supply alternation between the first phase 36 and the second phase 38 is carried out at high frequency, that is to say at a frequency of approximately 1 kHz.

The passage of electric currents between the first phase 36 and the second phase 38, at high frequency, and the switching of the switches thus generate a release of heat from the electrical or electronic components concerned, and therefore a release of heat in the housing defined by the protective casing, without the rotor being driven in rotation and risking deterioration due to blockage by the layer of frost. Maintaining this secondary control instruction for a sufficient amount of time can completely melt the frost, or at the very least decrease the frost layer and the corresponding blocking force.

However, the high frequency power supply alternation can cause overheating of the winding 34 at the level of the first phase 36 and the second phase 38 and potentially degrade this portion of the winding 34. To avoid this risk of overheating, the instruction secondary control can generate a change in the supply alternation, passing for example from an alternation between the first phase 36 and the second phase 38 of the winding 34 to an alternation between the second phase 38 and another phase 40 of the winding 34. The change in this phase supply alternation therefore makes it possible to avoid overheating of the winding 34 while continuing to release heat within the protection device 4 without driving the rotor 26 in rotation around the axis of rotation A. The secondary control instruction can be configured to perform a single or multiple phase alternation changes during the period of heat release by winding 34.

The secondary control instruction generates this supply alternation between two phases of the winding 34 for at least one millisecond (1ms). Following this duration, the control module 30 can again issue the main control instruction to generate the main operation of the electric motor 18, or else launch a request to determine whether a new secondary control instruction must be launched. Alternatively or additionally, if locking of the rotor 26 recurs, the control module 30 can issue the secondary control instruction again or block the operation of the electric motor 18.

According to a second embodiment, the secondary control instruction causes the defrosting of the protection device 4 by generating a power supply at a reduced frequency of the winding 34 compared to the supply frequency range generated by the main control instruction. On the other hand, it should be noted that in this second embodiment, the succession of the phase power supplies is the same as for the main control instruction and reference may be made thereto.

More particularly, and as illustrated in FIG. 11, the secondary control instruction like the main control instruction have the function of generating rotating magnetic fields according to a non-limiting example represented here in the counter-clockwise direction. a watch. The main control instruction can alternatively generate a set of clockwise rotating magnetic fields as well. The main control instruction first begins by generating an electric current from the first phase 36 to the second phase 38, generating a magnetic field with a first North pole 36a corresponding to the first phase 36 and a second South pole 38b corresponding to the second phase 38. Then, the main control instruction generates an electric current flowing from the first phase 36 to the other phase 40, generating a magnetic field with a first North pole 36a corresponding to the first phase 36 and a second South pole 40b corresponding to the other phase 40. The main control instruction then generates an electric current flowing from the second phase 38 to the other phase 40, generating a magnetic field with a first North pole 38a corresponding to the second phase 38 and a second South pole 40b corresponding to the other phase. The main control instruction then generates an electric current from the second phase 38 to the first phase 36, generating a magnetic field with a first North pole 38a corresponding to the second phase 38 and a second South pole 36b corresponding to the first phase. Subsequently, the main control instruction generates an electric current from the other phase 40 to the first phase 36, generating a magnetic field with a first North pole 40a corresponding to the other phase 40 and a second South pole 36 corresponding in the first phase. Finally, the main control instruction generates an electric current from the other phase 40 to the second phase 38, generating a magnetic field with a first North pole 40a corresponding to the other phase 40 and a second South pole 38b corresponding to the second stage 38.

The first magnetic element 42, or permanent magnet 42, is successively attracted by the poles corresponding to a South pole while the second magnetic element 44, arranged on the rotor opposite to the first magnetic element 42, is successively attracted by the poles corresponding to a North Pole.

These six stages of current flow form a current flow loop that repeats over a range of frequencies defined by the main control instruction. At start-up and according to the main control instruction, the frequency of formation of these loops is low to allow the rotor 26 to be rotated around the axis of rotation A from a stationary position, as mentioned above. considering the motor excitation constant. The frequency of formation of these loops then gradually increases, simultaneously increasing the speed of rotation of the rotor 26 around the axis of rotation A. The frequency of formation of these loops increases and then stagnates once the speed of rotation of the rotor 26 and of the moving part of the protection device 4 reaches approximately 10,000 revolutions/min. After the time required to clean the optical cover element 14, the frequency of formation of these loops decreases until it reaches a zero value, the speed of rotation of the rotor 26 also decreasing until the immobilization of the rotor 26.

The secondary control instruction generates a heating sequence for the supply of the winding 34 which takes up the supply diagram of the electric current circulation loops described above. Indeed, the secondary control instruction successively generates the power supply from the first phase 36 to the second phase 38, then to the other phase 40, then from the second phase 38 to the other phase 40, then from the second phase 38 to the first phase 36, then from the other phase 40 to the first phase 36 and finally from the other phase 40 to the second phase 38, also generating magnetic fields having North N and South S poles as described above.

The secondary control instruction makes it possible to generate these successive supplies at a frequency different from those of the frequency range used for the implementation of the main control instruction. Thus, the supply frequency generated by the secondary control instruction, according to the heating sequence making it possible to ensure the breakage of ice liable to block the rotation of the electric motor, is less than or equal to the minimum frequency of the frequency range of the main control instruction, or higher than the maximum frequency of the frequency range of the main control instruction. In what follows, the implementation of low frequency will be described in particular, but it should be noted that the implementation of frequency higher than the frequency range of the main mode of operation can have the same effect: the rotor remains static because due to its inertia, it does not have time to rotate in response to the presence of a magnetic field generated by a specific power supply that another magnetic field is already generated and tends to bring it back into position. A vibration of the rotor can thus be generated, which contributes to breaking the layer of frost trapping the device, in addition to the heating of the motor.

It will be understood that the minimum frequency of the frequency range of the main control instruction is the frequency at which the rotor 26 can be driven in rotation around the axis of rotation A. this minimum frequency, contrary to a main mode of operation where the frequency increases, makes it possible to try to set the rotor 26 in rotational motion, without risking that this rotation could produce damage to the electric motor 18 which would be maintained by an excessive layer of frost. The heating generated by the operation of the motor and the stress created by the slow rotation of the rotor contribute to reducing the layer of frost trapping the device.

It is understood that if the frequency is on the other hand lower than the minimum frequency of the frequency range of the main control instruction, the reduced loop frequency generated by the secondary control instruction is not sufficient to drive the rotor 26 in rotation around the axis of rotation A, due to the inertia generated by the mass of the rotor and the corresponding rotating part. The heating generated by the operation of the engine alone contributes to reducing the layer of frost trapping the device.

The secondary control instruction generates this low frequency power loop of Coil 34 for at least one second (1s). In accordance with what was previously mentioned, following this duration, the control module 30 can again issue the main control instruction to generate the main operation of the electric motor 18. If a blockage of the rotor 26 occurs produced again, the control module 30 can still issue the secondary control instruction or block the operation of the electric motor 18.

Of course, it follows from the above that the control module must decide, depending on its parameterization and/or the external conditions, which type of secondary control instruction it must issue. However, it is possible to envisage that the control module 30 is capable of initially transmitting a secondary control instruction causing the defrosting of the protection device 4 by generating a power supply at a reduced frequency of the coil 34 compared to the frequency range d power generated by the main control instruction then in a second time a second secondary control instruction causing the defrosting of the protection device 4 by generating an alternating power supply at high frequency between two phases of the winding 34.

In a third embodiment not illustrated here, the different phases of the winding are connected to the vehicle supply network independently of each other, so that it is possible to supply them simultaneously. In such a case, provision may be made for the secondary control instruction issued by the control module to be specific in that each phase is requested to be traversed simultaneously by a current of the same intensity. It follows from the above that the magnetic elements associated with the rotor are blocked in a position in which they are also repelled and attracted. As before, it is then possible to observe a heating of the electric motor without the rotor being driven in rotation.

A description will now be given, in relation to FIG. 12, of a defrosting method according to one aspect of the invention.

A start-up request 48 of the electric motor 18 is received by the control module 30. The control module 30 is thus placed in a first configuration E1a for the main start-up of the electric motor 18 and for this purpose it sends the main control instruction 52 mentioned previously, and which aims to successively supply the phases of the winding according to a given order and in a given frequency range. The control module 30 verifies the correct operation of the motor during a control step E2 validating or not the starting in rotation of the rotor 26. In the case where the rotor 26 has been correctly driven in rotation around the axis of rotation A, the winding 34 continues to be supplied according to the main control instruction 52 and the electric motor finds itself in a main operating state E1b.

When it results from the control step E2 that the rotor 26 has not succeeded in being driven in rotation around the axis of rotation A by locking of the rotor 26, the control module 30 is positioned in a step of waiting E3, during which the supply of the electric motor 18 is interrupted, the control module 30 issuing various requests to know the origin of the blockage. These requests can, for example, be a temperature measurement step E4 to find out whether the temperature inside and/or outside the protection device 4 is lower than a predefined threshold, for example 2° C. for this which is the internal temperature of the protection device. However, sending these requests is optional, as is the temperature measurement step E4.

Following the waiting step E3 and, alternatively, the temperature measurement step E4, the control module 30 performs a decision step E5 at the end of which the control module issues an instruction to immobilization 60, resulting in a step E7 of immobilization of the electric motor 18 and of the protection device 4, or issues a first secondary control instruction 64 and/or a second secondary control instruction 68 with the aim of breaking the layer of frost which is potentially the cause of the locked rotor. The control module 30 is configured to issue the secondary control instruction 64 when it detects frost in or around the protection device 4.

Initially, the control module 30 can carry out a first defrosting step E6a, by implementing a secondary control instruction of a first type 64, which corresponds to a supply of the coil 34 at low frequency, as described in the second embodiment. This low-frequency power supply can allow a release of calories in the protection device and aim to obtain micro-movements of the rotor 26 so that these micro-movements attempt to break the frost by a slight mechanical action. Once completed, the control module 30 restarts its protocol for starting the electric motor 18 at the main start-up step.

However, if the electric motor 18 does not start despite the performance upstream of the first defrosting step E6a, the control module 30 restarts the succession of protocol steps up to the decision step E5 as described above. Following this step, the control module 30 issues a second secondary control instruction 68 causing the electric motor 18 to execute a second defrosting step E6b.

This second defrosting step E6b consists in generating an alternating power supply between two phases of the high-frequency winding 34, as described in the first embodiment. This second defrosting step E6b produces a release of heat tending to significantly increase the internal temperature of the protection device 4 to melt the frost, without however driving the rotor in rotation and risking creating a breakage of the latter. In addition, this high-frequency alternating power supply could cause the vibration of the rotor 26, thus facilitating the defrosting and the setting in rotation of the rotor 26 around the axis of rotation A.

The control module 30 then and again performs the main start-up step E1 to start the electric motor 18, the rest of the process then being similar to what has been described above. The control module 30 is also configured to carry out the defrosting steps E6a, E6b one after the other or only one of the two defrosting steps E6a, E6b according to a defined number of attempts. In addition, the control module is configured to perform a defined number of attempts to start the electric motor 18 which, if all the attempts have failed, will lead to the immobilization of the rotor 26 of the electric motor 18.

In addition, the control module 30 can be configured to issue the first secondary control instruction 64 and/or the second secondary control instruction 68 in prevention. For example, the control module 30 can issue the first secondary control instruction 64 and/or the second secondary control instruction 68 before issuing the main control instruction 52 when a driver switches on the ignition or starts the vehicle 1 equipped with an optical assembly 2, comprising at least one sensor/transmitter 3 and the protection device 4 according to the invention.

Figure 13 illustrates the implementation of the invention in a protection device with a single-phase motor. The control module 30 is configured to issue control instructions aimed at circulating in one direction then in the other an electric current in a coil 35 comprising only one coil and thus generate the creation of a North pole and a South pole on either side of the air gap 31 in which the rotor 26 is able to move. According to the invention, the control module 30 is able to issue secondary control instructions to generate a sequence of heating likely to raise the temperature of the electric motor with the rotor 26 which moves little or not in the stator 28. It is understood in relation to what has been described previously that this heating sequence may in particular differ from the sequence corresponding to the main mode of operation by the winding supply frequency in one direction and then in the other, by providing a frequency of a value lower or higher than those of the supply frequency range of the operating mode main ionization. Furthermore, provision could be made to generate a heating sequence by modifying the order of supply, by providing only continuous supply in one direction for a long period.

The invention cannot however be limited to the means and configurations described and illustrated here, and it also extends to any equivalent means or configuration described and illustrated here, and it also extends to any equivalent means or configurations and to any combination technique operating such means.

Claims (10)

A device (4) for protecting a sensor/transmitter (3) of a vehicle (1), the protective device (4) comprising a protective housing (16) configured to house the sensor/transmitter (3) and mounted mobile around an axis of rotation (A), a transparent cover element (14) secured to the protective casing (16) and configured to be placed in the transmission/reception field of the sensor/transmitter (3), and an electric motor (18) coupled to the protective housing (16) for rotating the housing (16) and the transparent cover member (14), the electric motor (18) being an electronically commutated motor comprising a stator (28) and a rotor (26) such as the stator (28) or the rotor (26) carries a winding (34, 35) comprising at least one coil and supplied with current via a sequence controlled by a control module (30 ) and the rotor (26) or the stator (28) carries magnetic elements (42, 44), the rotor (26) being rotatable around or i interior of the stator (28) under the effect of the movement of the magnetic elements in magnetic fields, the control module (30) being configured to generate a main control instruction (52) in which the supply of the winding (34, 35 ) is controlled according to a main sequence defined to create a set of main magnetic fields able to drive the rotor (26) in rotation in a range of main rotational speeds, characterized in that the control module (30) is moreover configured to issue a secondary control instruction (64, 68) in which the supply of the coil (34, 35) is controlled according to at least one heating sequence distinct from said main sequence so as to generate a set of magnetic fields different from the main set of magnetic fields and configured to generate heating of the electric motor (18) by leaving the rotor (26) stationary or rotating at a speed of lower value eur to those of the main rotational speed range. A protection device (4) according to claim 1, wherein the winding (34) comprises different phases (36, 38, 40), the main control instruction (52) being such that the supply of the different phases (36, 38, 40) of the winding (34) is controlled according to a defined main sequence with a given phase supply order and a given supply frequency range, the secondary control instruction (64, 68) being such that the heating sequence for supplying the different phases (36, 38, 40) of the winding (34) has a supply order different from the order of said defined main sequence and/or a supply frequency different from the given supply frequency range. A protection device (4) according to claim 2, wherein a defined heating sequence of the secondary control instruction (68) consists of an alternating supply between two phases (36, 38; 38, 40; 36, 40) the winding (34), A protection device (4) according to claim 3, wherein the alternation of the supply of the secondary control instruction (64, 68) is carried out at a higher frequency than that of the main control instruction (52 ). A protection device (4) according to claim 4, wherein the control module (30) is configured to modify the secondary control instruction (68) beyond a given lapse of time, said secondary control instruction ( 68) being modified so as to generate an alternating supply of two other phases (36, 38; 38, 40; 36, 40) of the winding (34). Protection device (4) according to Claim 1, in which each phase (36, 38, 40) of the winding (34) is supplied independently of one another, characterized in that the secondary control instruction (64, 68) generates a similar power supply for each phase (36, 38, 40) of the winding (34). Protection device (4) according to Claim 2, in which the secondary control instruction (64) consists of supplying the phases (36, 38, 40) of the winding (34) one after the other, in the given command of the main control instruction (52), at a frequency of a value lower than that of the frequency range of the main control instruction (52). A protection device (4) according to any preceding claim, wherein the control module (30) is configured to generate the secondary control instruction (64, 68) when a driver switches the ignition on or starts the vehicle (1), and/or when the control module (30) detects abnormal resistance to drive the rotor (26) of the electric motor (18) in rotation and/or when the temperature of the vehicle (1) is at least below 2°C. Method for defrosting the protection device (4) according to one of Claims 1 to 8, in which at least one step of defrosting (E6a, E6b) of the protection device (4) is carried out during which an instruction main control (52) of the main operation of the electric motor (18) associated with the protection device (4) into a secondary control instruction (64, 68), by reducing the frequency of the supply switchings of the motor winding ( 18) or by modifying the supply switching sequences so as to generate an alternating supply of two phases (36, 38; 36, 40; 38, 40) at high frequency. Detection assembly (2) comprising at least one sensor/transmitter (3) and at least one protection device (4) according to any one of Claims 1 to 8.