FR3142973A1 - Gear motor, wiping device and associated motor vehicle - Google Patents

Abstract

Gear motor, wiping device and associated motor vehicle The present invention relates to a geared motor (6), in particular for a motor vehicle wiping device (1), comprising: - an electric motor (7), - a reduction gear (8) configured to cooperate with the electric motor (7) so as to to transform the values of the torque and the speed of the electromagnetic part to the forces necessary at the output of the geared motor (6) in which the reduction gear (8) comprising an endless screw (17) and a nut (15) configured to move the along the endless screw (17), one of the nut (15) or the endless screw (17) being configured to be coupled in rotation to the electric motor (7). Fig.1

Description

Geared motor, wiping device and associated motor vehicle

The present invention is part of the field of geared motors and in particular geared motors used in motor vehicle wiping devices to drive the wiper blades.

These geared motors comprise an electric motor and a reducer rotatably coupled to the electric motor and configured to produce a predetermined reduction ratio.

In the case of wiping devices, the output of the geared motor is generally coupled to a linkage allowing several wiping blades to be set in motion.

However, the reducer includes mechanical connections that can induce high mechanical losses.

Indeed, in particular with the use of reversible motors configured to rotate in a first direction of rotation to drive the wiper arms in a first direction and in a second direction of rotation to drive the wiper arms in a second direction of rotation, a reducer comprising a worm screw and a toothed wheel configured to mesh with the worm screw can have very significant mechanical losses of up to 50%. The losses are also very significant when the geared motor is used in reverse, for example under the effect of the air pressure exerted on the wiper blades in the case of a wiping device. These losses are dissipated in the reducer in the form of heat.

To compensate for these losses, it is advisable to use an electric motor with a high power, for example a power of 40 W.

However, particularly in the case of electric vehicles, such high-power electric motors result in increased electricity consumption and tend to reduce the vehicle's range.

It is therefore necessary to find a solution to reduce the mechanical losses linked to the reducer and possibly to recover part of the energy transmitted by the wiper blades to the geared motor, for example under the effect of the action of the air on the wiper blades.

For this purpose, the present invention relates to a geared motor, in particular for a motor vehicle wiping device comprising:
-an electric motor,
- a reducer configured to cooperate with the electric motor so as to transform the values of the torque and speed of the electromagnetic part of the electric motor to the forces required at the output of the geared motor,
the reducer comprising a worm screw and a nut configured to move along the worm screw, one of the nut and the worm screw being configured to be rotatably coupled to the electric motor.

Using a reducer comprising a worm screw and a nut configured to move along the worm screw reduces the friction of the reducer compared to a solution comprising a worm screw and a toothed wheel meshing with the worm screw.

According to another aspect of the present invention, the electric motor is configured to rotate the reducer nut to produce a translational movement of the reducer worm screw.

According to another aspect of the present invention, the electric motor is configured to rotate in a first predetermined direction of rotation to a first extreme position of the worm screw and then in a second direction of rotation opposite the first direction of rotation to a second extreme position of the worm screw to produce a reciprocating movement of the worm screw between the two extreme positions.

According to another aspect of the present invention, the worm screw comprises a threaded central portion, a first end portion of non-circular section configured to be blocked in rotation by a first guide ring and a second end portion of non-circular section configured to be blocked in rotation by a second guide ring.

According to another aspect of the present invention, the electric motor is configured to rotate the worm screw of the reducer to produce a translational movement of the nut of the reducer.

According to another aspect of the present invention, the geared motor also comprises a drive part rotatably mounted about a drive axis perpendicular to the worm screw, said drive part comprising a U-shaped arm whose hollow is configured to receive a pin linked to the nut of the reducer so that the translation of the nut of the reducer causes the rotation of the drive part.

Such a drive part makes it possible to convert the translational movement of the nut into rotational movement, thereby simplifying or eliminating the linkage.

According to another aspect of the present invention, the reducer comprises a ball screw in which the nut comprises a ball circulation channel, the combination of the ball circulation channel and the thread of the worm screw forming an endless loop of ball circulation.

The use of a ball screw helps to minimize friction linked to the reducer.

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

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

The present invention also relates to a motor vehicle wiping device comprising:
- a geared motor as described above,
- at least one wiping arm configured to receive a wiping blade,
- a linkage interposed between the geared motor and at least one wiper arm.

According to another aspect of the present invention, the wiping device comprises two wiping arms, the linkage forming a deformable parallelogram connected to the output of the geared motor to drive the two wiping arms in a back-and-forth movement.

The present invention also relates to a motor vehicle comprising a wiping device as described above.

Other characteristics and advantages of the invention will appear more clearly on reading the following description, given as an illustrative and non-limiting example, and the appended drawings among which:

represents a schematic view of a wiping device comprising two wiping arms;

represents a schematic view of a geared motor and a linkage of a wiping device;

represents a schematic sectional view of a ball screw;

represents a schematic perspective view of a geared motor according to a first embodiment;

represents a schematic perspective view of the interior of the geared motor of the showing the rotating part and the electromagnetic part of the geared motor;

represents a schematic perspective view of a geared motor according to a second embodiment;

represents a schematic perspective view of the interior of the geared motor of the showing the rotating part and the electromagnetic part of the geared motor;

represents a schematic perspective view of a geared motor according to a third embodiment;

In these figures, identical elements have the same references.

The following embodiments are examples. Although the description refers to one or more embodiments, this does not necessarily mean that each reference is 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.

The present invention relates to a geared motor 6. The geared motor 6 is for example used in a motor vehicle wiping device 1 but other uses are also possible.

There represents a schematic view of a wiping device 1 of a motor vehicle. The wiping device 1 is for example placed on the front or rear windshield of the motor vehicle. The wiping device 1 comprises one or more wiping arms 3, two in the case of the , configured to receive 5 wiper blades.

The wiping device 1 also comprises a geared motor 6 configured to drive the wiping arms, for example via a linkage 9 configured to move the wiping arm(s) 3 from the movement provided at the output of the geared motor 6. The linkage 9 comprises, for example, a deformable parallelogram mechanism, better visible in the , whose wiping arms 3 are connected to two parallel sides of the parallelogram.

The geared motor 6 comprises an electric motor 7, for example a brushless and reversible electric motor (i.e. capable of rotating in one direction of rotation and in the other direction of rotation), and a mechanical reducer 8 coupled in rotation to the electric motor 7 so as to adapt the values of the torque and the speed provided by the electromagnetic part of the electric motor 7 to the forces required at the output of the geared motor 6 to drive the wiping arms.

The mechanical reducer 8 is configured to produce a predetermined reduction ratio.

The mechanical reducer 8 includes a worm screw and a nut configured to move along the worm screw. Thus, the worm screw may be rotatably coupled to the electric motor to drive translational movement of the nut along the worm screw or, alternatively, the nut may be rotatably coupled to the electric motor to drive translational movement of the worm screw relative to the nut.

According to a first embodiment configuration, the nut is a simple nut screwed onto the worm screw.

According to a second embodiment configuration shown in the sectional view of the , the reducer 6 comprises a ball screw 13 configured to obtain this reduction ratio and to convert the rotational movement of the output shaft of the electric motor 3 into a translational movement.

The ball screw 13 comprises a nut 15 in which a circulation channel 15a for balls 19 is provided. The nut 15 is arranged around a worm screw 17 formed by a threaded shaft whose threads located inside the nut 15 form, in combination with the circulation channel 15a, an endless loop for circulation of balls 19. The diameter of the circulation channel 15a is preferably similar to the diameter of the threads of the worm screw 17. The ball screw 13 also comprises a plurality of balls 19 arranged in the endless loop.

Thus, the relative rotation of the nut 15 with respect to the worm screw 17 causes the movement of the balls 19 in the circulation channel which produces a relative translation of the nut 15 with respect to the worm screw 17 (in the axial direction of the worm screw). The ball screw 13 makes it possible to reduce the friction between the nut 15 and the worm screw 17.

According to a first embodiment of the geared motor 6 shown in FIGS. 4 and 5, the electric motor 7 is configured to drive the nut 15 in rotation. The worm screw 17 comprises a threaded central portion 17a and non-threaded end portions 17b. The non-threaded portions 17b have, for example, a non-circular section, in particular a rectangular section. The geared motor 6 comprises means for blocking the rotation of the worm screw, for example two rings 20 arranged respectively at the end portions 17b. The rings 20 comprise a through-hole of a shape complementary to the section of the end portions 17b to allow translation of the worm screw 17 while blocking its rotation. The rings 20 as well as the nut 15, the threaded part 17a of the worm screw 17 and the electric motor 7 can be arranged in a casing 21 of the geared motor 6 as shown in the .

Thus, in operation, the rotation of the output shaft of the electric motor 7 in a first direction of rotation causes the rotation of the nut 15 in a first direction of rotation and the movement of the worm screw 17 in translation in a first direction while the rotation of the output shaft of the electric motor 7 in a second direction of rotation, opposite to the first direction of rotation, causes the rotation of the nut 15 in a second direction of rotation, opposite to the first direction of rotation, and the movement of the worm screw 17 in translation in a second direction opposite to the first direction.

The worm screw 17 is for example arranged on one side of the deformable parallelogram of the wiping device 1 so that the translation from one side to the other of the worm screw 17 causes the back and forth movement of the wiping arms 3.

The electric motor 7 is for example configured to rotate in a first direction of rotation to a first extreme position of the worm screw 17 associated with a first extreme position of the wiping arms 3 and in a second direction of rotation, opposite to the first direction of rotation, to a second extreme position of the worm screw 17 associated with a second extreme position of the wiping arms 3. One of the extreme positions corresponds for example to a rest position in which the electric motor 7 positions the wiping arms 3 when the wiping device 1 is stopped. Alternatively, the rest position may correspond to a third extreme position.

According to a second embodiment of the geared motor 6 shown in FIGS. 6 and 7, the electric motor 7 is configured to drive the worm screw 17 in rotation. The worm screw 17 is for example integral in rotation with the output shaft of the electric motor 7. The nut 15 is blocked in rotation, for example via a pin 23 configured to be housed in a groove 25 extending in the axial direction of the worm screw as shown in FIG. . The groove 25 is for example formed in a casing 27 of the geared motor 6 containing the electric motor 7, the worm screw 17 and the nut 15. The pin 23 is for example connected to one side of the deformable parallelogram of the linkage 9. The different elements may also be similar to the elements of the first embodiment.

The electric motor 7 is for example configured to rotate in a first direction of rotation to a first extreme position of the nut 15 associated with a first extreme position of the wiping arms 3 and in a second direction of rotation, opposite to the first direction of rotation, to a second extreme position of the nut 15 associated with a second extreme position of the wiping arms 3. One of the extreme positions corresponds for example to a rest position in which the electric motor 7 positions the wiping arms when the wiping device 1 is stopped. Alternatively, the rest position may correspond to a third extreme position.

According to a third embodiment of the geared motor 6 shown in the , the electric motor 7 is configured to drive the worm screw 17 in rotation as in the second embodiment. The third embodiment differs from the second embodiment by the presence of a drive part 29 configured to cooperate with the pin 23. The drive part 29 is rotatably mounted about a drive axis 29a arranged perpendicular to the axial direction of the worm screw 17. The drive part 29 comprises a U-shaped arm whose hollow is configured to receive the pin 23 linked to the nut 15.

Thus, the rotation of the electric motor 7 causes the translational movement of the nut 15 along the worm screw 17 which causes the sliding of the pin 23 in the hollow of the U of the drive part 29 and the rotation of the drive part 29 around the drive axis 29a. The drive part 29 is for example configured to be connected to an element of the deformable parallelogram of the linkage 13. The electric motor 7, the worm screw 17, the nut 15 and a part of the drive part 29 can be arranged in a casing 27' of the geared motor 6.

Thus, in operation, the rotation of the electric motor 7 in a first direction of rotation causes the rotation of the worm screw 17 in a first direction of rotation, the movement of the nut 15 in translation in a first direction and the rotation of the drive part 29 in a first direction of rotation while the rotation of the output shaft of the electric motor 7 in a second direction of rotation, opposite to the first direction of rotation, causes the rotation of the worm screw 17 in a second direction of rotation, opposite to the first direction of rotation, the movement of the nut 15 in translation in a second direction opposite to the first direction and the rotation of the drive part 29 in a second direction of rotation, opposite to the first direction of rotation.

The electric motor 7 is for example configured to rotate in a first direction of rotation to a first extreme position of the nut 15 associated with a first extreme position of the wiping arms 3 and in a second direction of rotation, opposite to the first direction of rotation, to a second extreme position of the nut 15 associated with a second extreme position of the wiping arms 3.

The use of the drive part 29 makes it possible to obtain a rotational movement at the output of the geared motor 6 and to smooth the transitions between the back-and-forth movements of the wiping arms 3.

The different embodiments presented above can be adapted to the different embodiment configurations presented above.

The present invention relates to all types of geared motors 6 comprising an electric motor 7 and a reducer 8 and all types of wiping devices 1 comprising a geared motor 6, at least one wiping arm 3 and a linkage 9 for driving the at least one wiping arm 3 from the geared motor 6 and is not limited to the types of linkage shown in the various figures nor to a wiping device comprising two wiping arms.

The present invention also relates to a motor vehicle comprising a wiping device as described above. The wiping device 1 is for example arranged at a front or rear windshield of the motor vehicle.

Thus, the use of a geared motor 6 comprising a worm screw 17-nut 15 assembly and in particular a ball screw 13 to achieve the mechanical reduction makes it possible to significantly reduce friction at the reducer 8 and thus improve the overall efficiency of the geared motor 6. The losses linked to mechanical friction in the wiping device 1 are thus reduced. This reduction in losses makes it possible, for example, to use a lower power motor and thus reduce the energy consumption of the wiping device 1.

Claims (12)

Geared motor (6), in particular for a motor vehicle wiping device (1) comprising:
- an electric motor (7),
- a reducer (8) configured to cooperate with the electric motor (7),
the reducer (8) comprising a worm screw (17) and a nut (15) configured to move along the worm screw (17), one of the nut (15) or the worm screw (17) being configured to be rotatably coupled to the electric motor (7). Geared motor (6) according to claim 1 in which the electric motor (7) is configured to rotate the nut (15) of the reducer (8) to produce a translational movement of the worm screw (17) of the reducer (6). Geared motor (6) according to claim 2 wherein the electric motor (7) is configured to rotate in a first predetermined direction of rotation to a first extreme position of the worm screw (17) then in a second direction of rotation opposite to the first direction of rotation to a second extreme position of the worm screw (17) to produce a back and forth movement of the worm screw (17) between the two extreme positions. Geared motor (6) according to claim 3, in which the worm screw (17) comprises a threaded central part (17a), a first end portion (17b) of non-circular section configured to be blocked in rotation by a first guide ring (19) and a second end portion (17b) of non-circular section configured to be blocked in rotation by a second guide ring (20). Geared motor (6) according to claim 1 in which the electric motor (7) is configured to drive in rotation the worm screw (17) of the reducer (8) to produce a translational movement of the nut (15) of the reducer (8). Geared motor (6) according to the preceding claim also comprising a drive part (29) rotatably mounted around a drive axis (29a) perpendicular to the worm screw (17), said drive part (29) comprising a U-shaped arm whose hollow is configured to receive a pin (23) linked to the nut (15) of the reducer (8) so that the translation of the nut (15) of the reducer (8) causes the rotation of the drive part (29). Geared motor (6) according to one of the preceding claims, in which the reducer (8) comprises a ball screw (13). Geared motor (6) according to one of the preceding claims in which the electric motor (7) is a brushless motor. Geared motor (6) according to one of the preceding claims in which the electric motor (7) is a reversible motor. Wiping device (1) for a motor vehicle comprising:
- a geared motor (6) according to one of the preceding claims,
- at least one wiping arm (3) configured to receive a wiping blade (5),
- a linkage (9) interposed between the geared motor (8) and the at least one wiping arm (3). Wiping device (1) for a motor vehicle according to the preceding claim comprising two wiping arms (3), the linkage (9) forming a deformable parallelogram and in which the linkage (9) is connected to the output of the geared motor (6) to drive the two wiping arms (3) in a back-and-forth movement. Motor vehicle comprising a wiping device (1) according to one of claims 10 or 11.