Reduction drive motor, motor vehicle wiping device, and associated motor vehicle

Abstract

The present invention relates to a reduction drive motor (7) for a motor vehicle wiping device, comprising: - an electric motor (3) configured to be powered by a main electric power source (15, 15') and to rotate an output shaft, - and a mechanical reduction gear (5) coupled to the output shaft of the electric motor (3), characterized in that the reduction drive motor (7) also comprises an electric accumulator (17) forming a secondary electric power source for powering the electric motor (3), said electric accumulator (17) being configured to recover at least some of the electric power generated by the electric motor (3) when a torque is applied to the output shaft of the electric motor (3) via the mechanical reduction gear (5).

Description

Geared motor, motor vehicle wiping device and associated motor vehicle

[0001] The present invention falls within the field of motor vehicle wiping devices for driving the wiper blades and in particular energy recovery via such a device.

[0002] These wiping devices generally comprise an electric geared motor and a linkage for converting the rotational movement at the output of the electric motor into a reciprocating movement of the wiping arms on which the wiping blades are mounted.

[0003] However, during a cycle (back and forth movement of the wiper blades on the windscreen), the torque supplied by the geared motor varies and can even be negative due to the inertia of the blades when their speed decreases or under the effect of the air when the wiper arms are moved towards the top of the windscreen.

[0004] In order to reduce the overall consumption of the wiping device, it is appropriate to recover part of the mechanical energy provided by this negative torque.

[0005] Indeed, particularly in the case of electric vehicles, it is important to limit the consumption of various electrical equipment because this can impact the vehicle's autonomy.

[0006] Furthermore, in the case of electric vehicles, the geared motor is generally powered from the vehicle's main battery via a voltage converter to adapt the voltage supplied to the geared motor. The converter is, for example, a 400-450V DC / 12-24V DC converter. However, using the geared motor as a current generator when the torque is negative can seriously damage the electrical components of the geared motor's power supply circuit, particularly the voltage converter and also the battery.

[0007] It is therefore necessary to find a solution that allows at least part of the energy supplied by the wiping device to be recovered during a cycle without risking damage to the elements of the power supply circuit. In addition, the cost of such a solution must be limited.

[0008] To this end, the present invention relates to a geared motor for a motor vehicle wiping device comprising:- an electric motor configured to be powered by a main electrical power source and to rotate an output shaft,- a mechanical reducer coupled to the output shaft of the electric motor, in which the geared motor also comprises an electrical accumulator forming a secondary electrical power source for powering the electric motor, said electrical accumulator being configured to recover at least part of an electrical energy generated by the electric motor when a torque is applied to the output shaft of the electric motor via the mechanical reducer.

[0009] The present invention also relates to a motor vehicle wiping device comprising:- an electric motor configured to rotate an output shaft,- at least one wiping arm configured to receive a wiper blade,- a mechanism interposed between the output shaft of the electric motor and the at least one wiping arm,- a main electrical energy source configured to power the electric motor, in which the wiping device also comprises an electrical accumulator forming a secondary electrical energy source for powering the electric motor, said electrical accumulator being configured to recover at least a portion of electrical energy generated by the electric motor when a torque is applied to the output shaft of the electric motor.

[0010] According to another aspect of the present invention, the wiping device also comprises a blocking element configured to prevent an electric current generated by the electric motor from being transmitted to the main electrical power source.

[0011] According to another aspect of the present invention, the blocking element is a diode or a transistor.

[0012] According to another aspect of the present invention, the mechanism comprises a reducer.

[0013] According to another aspect of the present invention, the time constant of the electric accumulator is less than or equal to 1s.

[0014] According to another aspect of the present invention, the electric accumulator comprises a supercapacitor.

[0015] According to another aspect of the present invention, the main electrical energy source is a main battery of the motor vehicle.

[0016] According to another aspect of the present invention, the motor vehicle wiping device also comprises a DC-DC voltage converter interposed between the main electrical energy source and the electric motor.

[0017] According to another aspect of the present invention, the electric motor is a reversible motor.

[0018] According to another aspect of the present invention, the electric motor is a brushless motor.

[0019] The present invention also relates to a motor vehicle comprising a wiping device as described previously.

[0020] Other characteristics and advantages of the invention will appear more clearly on reading the following description, given by way of illustrative and non-limiting example, and the appended drawings among which:

[0021] represents a schematic view of a wiping device of a motor vehicle;

[0022] represents a schematic view of an electrical circuit supplying power to an electric motor of a wiping device of a motor vehicle according to a first embodiment of the present invention;

[0023] represents a schematic view of an electrical circuit supplying power to an electric motor of a wiping device of a motor vehicle according to a second embodiment of the present invention.

[0024] In these figures, identical elements have the same references.

[0025] The following embodiments are examples. Although the description refers to one or more embodiments, this does not necessarily mean that each reference relates to the same embodiment, or that the features apply only to a single embodiment. Single features of different embodiments may also be combined or interchanged to provide other embodiments.

[0026] The diagram represents a diagram of a wiping device 1 of a motor vehicle. The wiping device 1 comprises an electric motor 3, for example a brushless direct current motor. The electric motor 3 may be a reversible motor configured to drive an output shaft of the electric motor 3 in a first direction of rotation and in a second direction of rotation opposite to the first direction of rotation.

[0027] The wiping device 1 may also comprise a mechanical reducer 5 coupled to the output shaft of the electric motor 3 to form a geared motor 7 whose casing contains the electric motor 3 and the mechanical reducer 5. The mechanical reducer 5 is for example produced by a worm screw and a toothed wheel meshing with the worm screw and makes it possible to use an electric motor 3 having a reduced torque but a high rotation speed.

[0028] The wiping device 1 also comprises at least one wiping arm 9 on which a wiping blade 11 is arranged, two wiping arms 9 in the case of the and a linkage 13 connecting the geared motor 1 to the wiping arms 9. The linkage 13 and possibly the reducer 7 thus form a mechanism connecting the output shaft of the electric motor 3 to the wiping arm(s) 9.

[0029] Thus, in operation, the rotation of the output shaft of the electric motor 3 is transmitted to the linkage 13 via the mechanical reducer 5. The linkage 13 is configured to convert the rotational movement at the output of the mechanical reducer 5 and drive the wiping arms 9 in a reciprocating movement.

[0030] The represents a first example of an electrical circuit for supplying power to the electric motor 3. The supply circuit comprises a main electrical energy source 15 for supplying power to the electric motor 3. This main electrical energy source 15 corresponds for example to a battery supplying power to the vehicle in the case of an electric or hybrid vehicle.

[0031] The power supply circuit also comprises a DC / DC voltage converter 19 produced here by an H-bridge comprising four transistors 21 distributed over the branches of the H-bridge. The voltage converter 19 is configured to adapt the voltage delivered by the main energy source 15, for example 400V or 450V to the supply voltage of the electric motor 3, for example 12V or 24V. Other types of voltage converter can also be used.

[0032] The power supply circuit also comprises a secondary source of electrical energy for powering the electric motor 3 produced by an electrical accumulator 17 such as a supercapacitor or a battery. The electrical accumulator 17 is configured to recover at least a portion of the electrical energy generated by the electric motor 3 when the latter acts as a generator, that is to say when a torque is applied to the output shaft of the electric motor 3. This may in particular be the case when the torque supplied by the electric motor 3 to the linkage 13 is reduced (slowing down of the wiper arm 9), due to the inertia of the wiper arm 9 or when the air creates a driving torque on the wiper arm 9 due to the speed of the vehicle and / or the speed of the wind.

[0033] Indeed, during a cycle, the wiping arm 9 passes from a first position called the internal wiping position (“In-Wipe” in English) in which the wiping blade 11 is positioned on the lower part of the windshield to a second position called the external wiping position (“Out-Wipe” in English) in which the wiping blade 11 is positioned on the upper part of the windshield and then returns to its first position. During a cycle, the speeds of the wiping arm 9 are therefore zero when the wiping blade 9 is in the first or second position so that the torque supplied by the geared motor 7 to the wiping arm 9 can be negative when the wiping arm 9 approaches the first or second position due to the inertia of the wiping arm 9 while its speed decreases. When the torque is negative, torque is supplied to the output shaft of the electric motor 3 via the reducer 5.The electric motor 3 then acts as a generator and supplies an electric current to the power supply device. A negative torque may also occur due to the air flow driving the wiper arm 9, in particular when the wiper arm 9 moves from the first position to the second position.

[0034] Thus, the electric accumulator 17 is configured to store the electrical energy supplied by the electric motor 3 when it acts as a generator and to subsequently restore the accumulated electrical energy to power the electric motor 3 when it acts as a motor which transmits a torque to the linkage 13, in particular via the reducer 7. The power supply of the electric motor 3 can be carried out as a priority by the electric accumulator 17 and supplemented by the main electrical energy source 15 if the energy supplied by the electric accumulator 17 is insufficient.

[0035] Due to the duration of a cycle of the wiping arm 9, the time constant of the electric accumulator 17 must be sufficiently low, for example 1s or less, to be able to store the electrical energy when the torque is negative and the electric motor 3 acts as a generator and then to power the electric motor 3 when the torque becomes positive again.

[0036] The power supply circuit may also comprise a blocking element 23 for blocking an electric current transmitted from the electric motor 3 to the main electrical energy source 15 when the electric motor 3 operates in generator mode. The blocking element 23 is for example produced by a passive element such as a diode or by an active element such as a transistor or a switch 23 as shown in the. In the latter case, the transistor or switch 23 is controlled to be conducting (closed) when the electric motor 3 must be powered and blocking (open) when the electric motor 3 operates as a generator.

[0037] For this, the supply current transmitted to the electric motor 3 can be measured and the transistor (or switch) can be controlled according to the value (positive or negative) of the measured current.

[0038] The blocking element 23 thus makes it possible to protect the electrical or electronic components of the power supply device and in particular the main electrical energy source 15.

[0039] According to a second exemplary embodiment shown in the, the main electrical energy source 15' for supplying the electric motor 3 is an accessory battery, for example of a thermal vehicle.

[0040] The main electrical energy source 15' is for example configured to provide a voltage of 12V or 24V. In this case, there is no need for a voltage converter since the voltage delivered by the main electrical energy source 15' corresponds to the supply voltage of the electric motor 3. The blocking element 23 is similar to that of the embodiment of the and its operation is also similar, that is to say that the blocking element 23 prevents the transmission of an electric current from the electric motor 3 to the main electrical energy source 15' when the electric motor 3 operates as a generator.

[0041] The operation of the electric accumulator 17 is also similar and makes it possible to recover the electrical energy supplied by the electric motor 3 when it operates as a generator and to restore this electrical energy later to power the electric motor 3 when it must provide mechanical torque to the linkage 13.

[0042] The present invention also relates to a geared motor 7 comprising an electric motor 3, a mechanical reducer 5 and an electric accumulator 17 as described previously in which the electric accumulator 17 makes it possible to recover at least part of the electrical energy supplied by the electric motor when it operates in generator mode, that is to say when a torque is transmitted to the output shaft of the electric motor 3 via the mechanical reducer 5 and to subsequently restore the recovered electrical energy.

[0043] The electric accumulator 17 can be positioned in the same protective casing as the electric motor 3 and possibly as the mechanical reducer 7 so as to form a geared motor unit allowing energy recovery. The blocking element 23 can also be arranged in the casing of the geared motor or geared motor unit.

[0044] The present invention also relates to a motor vehicle comprising a wiping device 1 as described previously.

[0045] The use of an electric accumulator 17 configured to recover at least a portion of the electrical energy generated by the electric motor 3 when a torque is supplied to the output shaft of the electric motor 3 makes it possible to use the recovered energy to power the electric motor 3 when it must supply a torque on its output shaft and thus obtain a secondary source of electrical energy for powering the electric motor 3 making it possible to reduce the use of the main power source 15, 15', which makes it possible to reduce the overall energy consumption of the wiping system 1. In addition, the use of a blocking element 23 configured to block the electrical current supplied by the electric motor 3 when it operates as a generator to the main power source 15, 15' makes it possible to avoid damaging the latter.

Claims

Geared motor (7) for a motor vehicle wiping device comprising:- an electric motor (3) configured to be powered by a main electrical power source (15, 15') and to drive an output shaft in rotation,- a mechanical reducer (5) coupled to the output shaft of the electric motor (3), characterized in that the geared motor (7) also comprises an electric accumulator (17) forming a secondary electrical power source for powering the electric motor (3), said electric accumulator (17) being configured to recover at least a portion of electrical energy generated by the electric motor (3) when a torque is applied to the output shaft of the electric motor (3) via the mechanical reducer (5). Wiping device (1) for a motor vehicle comprising:- an electric motor (3) configured to rotate an output shaft,- at least one wiping arm (9) configured to receive a wiper blade (11),- a mechanism (5, 13) interposed between the output shaft of the electric motor and the at least one wiping arm (9),- a main electrical energy source (15, 15') configured to power the electric motor (3),characterized in that the wiping device (1) also comprises an electrical accumulator (17) forming a secondary electrical energy source for powering the electric motor (3), said electrical accumulator (17) being configured to recover at least a portion of electrical energy generated by the electric motor (3) when a torque is applied to the output shaft of the electric motor (3). A wiping device according to claim 2 also comprising a blocking element (23) configured to prevent an electric current generated by the electric motor (3) from being transmitted to the main electrical power source (15, 15'). A wiping device according to claim 3 wherein the blocking element is a diode or a transistor. Wiping device (1) for a motor vehicle according to one of claims 2 to 4 in which the mechanism (7, 13) comprises a reducer (7). Wiping device (1) for a motor vehicle according to one of claims 2 to 5 in which the time constant of the electric accumulator (17) is less than or equal to 1s. Wiping device (1) for a motor vehicle according to one of claims 2 to 6 in which the electric accumulator (17) comprises a supercapacitor. Wiping device (1) for a motor vehicle according to one of claims 2 to 7, in which the main electrical energy source (15, 15') is a main battery (15) of the motor vehicle. Wiping device (1) for a motor vehicle according to claim 8 also comprising a DC-DC voltage converter (19) interposed between the main electrical energy source (15) and the electric motor (3). Motor vehicle comprising a wiping device (1) according to one of claims 2 to 9.

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