Electromechanical actuator

Abstract

The present invention relates to an electromechanical actuator (1) comprising an electric motor (2) acting on a torque output element (6) able to be coupled with a mobile member of a transmission box of a vehicle, the torque output element (6) is configured to rotate about its axis of rotation between a first extreme position and a second extreme position defining an actuation range, the torque output element (6) is connected to the electric motor (2) by drive means (4, 5) comprising a first gear wheel (4) and a second gear wheel (5), the actuator (1) further comprises an electronic board (10). The electronic board (10) comprises a sensor (12) that faces a magnet (15) mounted on a third gear wheel (11), said third gear wheel (11) meshing with the second gear wheel (5) such that when the torque output element (6) makes n revolutions corresponding to the actuation range, the third gear wheel (11) makes only one single revolution at most.

Description

Description Title of the invention: Electromechanical actuator [1] The invention relates to an electromechanical actuator. More particularly, the invention relates to an electromechanical actuator that can be rotary or linear. [2] The invention applies, for example, to the field of actuators for a parking lock system for a vehicle gearbox, particularly a motor vehicle equipped with an automatic transmission, for example, a hybrid vehicle. The invention also applies to a parking lock system for a reduction gear associated with an electric vehicle motor. The gearbox or reduction gear will more generally be called a transmission. This locking system is better known by its English term "park lock." Such an actuator allows the transmission to be locked in the parking position by means of a lever engaging with a gear in the transmission. [3] The invention also applies to the field of actuators for a system of connecting / disconnecting components in the transmission of the aforementioned vehicles such as, for example, forks, synchronizers, selectors, etc... [4] It is typical with these designs for the actuator to be located outside the transmission and for the moving part to be actuated to be inside the transmission. In order for the actuator to reliably act on the moving part of the transmission, it is necessary to know the exact position of the moving part within the transmission. [5] In the case of a rotary actuator, one solution would be to count the number of revolutions of the actuator's torque output element to determine the position of the moving part, having prior knowledge of the number of revolutions required for the torque output element to traverse the entire actuation range of the moving part. This solution has the disadvantage of requiring the rotation position to be stored in a storage unit. Furthermore, in the case In the event of a power outage, the memorized position will be lost, which requires a complex learning procedure to implement. [6] One of the aims of the invention is to provide an actuator capable of solving the problems mentioned above. The actuator must be able to reliably and autonomously determine the position of the moving part in the gearbox over its entire actuation range without involving any elements external to the actuator. [7] Thus, the invention proposes an electromechanical actuator comprising an electric motor acting on a torque output element suitable for coupling with a moving part of a vehicle's transmission. The torque output element is configured to rotate about its axis of rotation between a first extreme position and a second extreme position defining an actuation range. The torque output element is connected to the electric motor by drive means comprising a first gear and a second gear. The actuator further comprises an electronic board including a sensor facing a magnet mounted on a third gear meshing with the second gear such that when the torque output element completes n revolutions corresponding to the actuation range, the third gear completes only one revolution at most. [8] This design thus makes it possible to recover the signal generated by the sensor associated with the angular position of the third toothed wheel, which makes it possible to know the angular position of the torque output element over its actuation range. [9] The moving part of the transmission is, for example, a roto-linear device. The rotary actuation range of the torque output element of the actuator corresponds to the linear actuation range of the moving part.

[0010] According to the invention, the actuation range of the torque output element is greater than one revolution. In other words, the actuation range of the torque output element is greater than 360°.

[0011] Preferably, the sensor is an absolute sensor, for example a Hall effect sensor.

[0012] According to the invention, the electric motor comprises a drive shaft extending along an axis X1 and a drive pinion; this drive pinion meshes with the The first gear, which is mounted to rotate freely around an axis X2, meshes in turn with the second gear, which is also mounted to rotate freely around an axis X3. According to a particular feature of the invention, the axes X1, X2, and X3 are parallel. This U-shaped design is particularly compact and optimized for integration into a vehicle.

[0013] According to the invention, the drive pinion and the three gear wheels have straight teeth. The teeth can also be helical.

[0014] According to the invention, the torque output element is a shaft rotationally linked to the second gear and is configured to rotate around the axis of rotation X3. In other words, the torque output element and the second gear are coaxial.

[0015] According to another feature of the invention, the third gear and the first gear are mounted to rotate relative to each other. In other words, the third gear and the first gear are coaxial. Due to the reduction ratio of the three gears, the third gear and the first gear rotate at different speeds.

[0016] A washer is positioned axially between the first gear and the third gear in order to limit wear due to friction.

[0017] According to the invention, the second gear is two-stage, the first stage meshes with the first gear and the second stage meshes with the third gear.

[0018] Advantageously, the reduction ratio between the second and third gears is chosen based on the number of revolutions the torque output element must make. For example, when the torque output element makes n revolutions to cover the entire actuation range, the reduction ratio must be greater than n. More precisely, when the torque output element makes n revolutions corresponding to the actuation range, the third gear makes a maximum of only one revolution. Therefore, the position of the torque output element can be easily determined by the angular position of the third gear, provided the reduction ratio between the second and third gears is known.

[0019] According to another feature of the invention, the electric motor, the motor pinion, the drive means, the third gear with the magnet, the electronic board with the sensor, and at least part of the torque output element are housed in a casing.

[0020] The invention, in general, relates to a rotary or linear electromechanical actuator comprising at least one of the above characteristics. In the case of a linear electromechanical actuator, the torque output element will be coupled to a roto-linear device.

[0021] Other features and advantages of the invention will become apparent from the following detailed example of an embodiment, with reference to the attached figures:

[0022] [Figure 1] represents a perspective view of the actuator according to the present invention;

[0023] [Figure 2] represents a front view of the actuator according to the present invention.

[0024] It should be noted that the figures disclose the invention in sufficient detail for its implementation, and these figures help to further define the invention if necessary. However, the invention should not be limited to the embodiment disclosed in the description.

[0025] With reference to [Figure 3] and [Figure 2], an electromechanical actuator is shown comprising an electric motor 2 acting on a torque output element 6 suitable for coupling with a moving part of a vehicle's transmission. The electric motor 2 is a brushed DC type and comprises a motor shaft extending along an axis X1 and a motor pinion 3 fixed to this shaft. The electric motor 2 is axially mounted in the housing (not shown) by a compression plate 21, known per se.

[0026] The torque output element 6 is configured to rotate about its axis of rotation between a first extreme position and a second extreme position, defining an actuation range. The actuation range of the torque output element 6 is greater than one revolution.

[0027] The torque output element 6 is connected to the electric motor 2 by drive means. These drive means comprise a first gear 4 and a second gear 5. The drive pinion 3 of the electric motor 2 meshes with the first gear 4, which is mounted to rotate about an axis X2 via a shaft 9. The first gear 4, in turn, meshes with the second gear 5, which is mounted to rotate about an axis X3. The drive pinion 3 and both gears 4 and 5 have spur gears. The torque output element 6 is a shaft rotationally connected to the second gear 5 and is configured to rotate about the axis of rotation X3. The torque output element 6 is guided in rotation by a bearing 8 and a plain bearing 7. A seal is located between the bearing 8 and the plain bearing 7.The end of the torque output element 6 is grooved so that it can be coupled to the moving part of the transmission box.

[0028] The axes X1, X2, X3 are parallel so that the actuator has a "U" shaped design.

[0029] The actuator 1 further includes a third gear 11 which meshes with the second gear 5. This third gear 11 carries a magnet 15 at one of its ends. This magnet 15 is preferably attached to the gear 11 by snap-fitting with hooks. Other means of attaching the magnets are also possible, in particular by gluing. The magnet 15 faces a sensor 12 mounted on an electronic board 10. The interaction of the magnet 15 with the sensor 12 allows the angular position of the third gear 11 to be detected.

[0030] A particular aspect of the invention is that the third gear 11 and the first gear 4 are mounted to rotate freely relative to each other. A washer 13 is positioned axially between the first gear 4 and the third gear 11.

[0031] The second gear 5 has two stages 51, 52. The first stage 51 meshes with the first gear 4, and the second stage 52 meshes with the third gear 11. The reduction ratio between the second gear 5 and the third gear 11 is chosen according to the number of revolutions that the torque output element 6 must make. In this case, the element The torque output element 6 must make 4 revolutions to cover the actuation range, the reduction ratio between the second gear 5 and the third gear 11 must therefore be greater than 4. It is thus possible to easily detect the position of the torque output element 6 thanks to the angular position of the third gear by knowing the reduction ratio between the second gear 5 and the third gear 11.

[0032] The motor pinion 3 and the three gear wheels 4, 5, 11 have straight teeth.

[0033] The electric motor 2, the motor pinion 3, the drive means 4, 5, the third gear 11 with the magnet 15, the electronic board 10 with the sensor 12, and at least part of the torque output element 6 are housed in a casing 14.

[0034] Although the invention has been described in connection with a particular embodiment, it is clearly not limited to it and includes all technical equivalents of the means described.

[0035] In claims, reference symbols in parentheses should not be interpreted as a limitation of the claim.

Claims

Claims

1. Electromechanical actuator (1) comprising an electric motor (2) acting on a torque output element (6) capable of being coupled with a movable member of a transmission box of a vehicle, the torque output element (6) is configured to rotate about its axis of rotation between a first extreme position and a second extreme position defining an actuation range, the torque output element (6) is connected to the electric motor (2) by drive means (4, 5) comprising a first toothed wheel (4) and a second toothed wheel (5), the actuator (1) further comprises an electronic card (10),characterized in that the electronic card (10) comprises a sensor (12) which faces a magnet (15) mounted on a third toothed wheel (11), said third toothed wheel (11) meshing with the second toothed wheel (5) so that when the torque output element (6) performs n turns corresponding to the actuation range, the third toothed wheel (11) only performs a maximum of one turn.,

2. Actuator (1) according to claim 1, characterized in that the actuation range of the torque output element (6) is greater than one revolution.

3. Actuator (1) according to claim 1 or 2, characterized in that the electric motor (2) comprises a motor shaft which extends along an axis X1 and a motor pinion (3), this motor pinion (3) meshes with the first toothed wheel (4) which is mounted to be able to rotate about an axis X2, this first toothed wheel (4) in turn meshes with the second toothed wheel (5) mounted to be able to rotate about an axis X3.

4. Actuator (1) according to one of the preceding claims, characterized in that the motor pinion (3) and the three toothed wheels (4, 5, 11) have straight or helical teeth.

5. Actuator (1) according to one of the preceding claims, characterized in that the torque output element (6) is a shaft rotatably connected to the second toothed wheel (5) and is configured to rotate about the axis of rotation X3.

6. Actuator (1) according to one of the preceding claims, characterized in that the third toothed wheel (11) and the first toothed wheel (4) are mounted to rotate relative to each other.

7. Actuator (1) according to claim 6, characterized in that a washer (13) is positioned axially between the first toothed wheel (4) and the third toothed wheel (11).

8. Actuator (1) according to one of the preceding claims, characterized in that the second toothed wheel (5) has two stages (51, 52), the first stage (51) meshes with the first toothed wheel (4) and the second stage (52) meshes with the third toothed wheel (11).

9. Actuator (1) according to one of the preceding claims, characterized in that the reduction ratio between the second toothed wheel (5) and the third toothed wheel (11) is chosen as a function of the number of revolutions that the torque output element (6) must make.

10. Actuator (1) according to one of the preceding claims, characterized in that the electric motor (2), the motor pinion (3), the drive means (4, 5), the third toothed wheel (11) with the magnet (15), the electronic card (10) with the sensor (12), and at least partly the torque output element (6) are housed in a housing (14).

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