Electromechanical actuator

Abstract

The present invention relates to an electromechanical actuator (1) comprising an electric motor (2) acting on a torque output element (6) adapted to be coupled with a moving part of a vehicle's transmission. 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 (4) and a second gear (5). The actuator (1) further comprises an electronic board (10). The electronic board (10) includes two sensors (12, 13), each facing a magnet (41, 51) associated with each gear (4, 5) in order to detect the angular position of each gear (4, 5). (See Figure 1 for abbreviations.)

Description

Title of the invention: Electromechanical actuator

[0001] The invention relates to an electromechanical actuator. More particularly, the invention relates to an electromechanical actuator that can be rotary or linear.

[0002] 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.

[0003] 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...

[0004] 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.

[0005] 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, provided that the number of revolutions required for the torque output element to traverse the entire actuation range of the moving part is known beforehand. This solution has the disadvantage of requiring the rotation position to be stored in a memory unit. Furthermore, in the event of a power failure, the stored position will be lost, necessitating a complex learning procedure.

[0006] One of the aims of the invention is to provide an actuator that solves 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.

[0007] 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 gearbox; the torque output element is configured to rotate about its axis of rotation between a first position The torque output element is connected to the electric motor via a drive mechanism comprising a first gear and a second gear. The actuator further includes an electronic board with two sensors, each facing a magnet associated with a gear, to detect the angular position of each gear.

[0008] This design thus makes it possible to recover two signals generated by the two angular position sensors of each toothed wheel for analysis by a controller capable of generating a signal corresponding to an angular position of the torque output element on its actuation range.

[0009] 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 two sensors are absolute sensors, for example, Hall effect sensors.

[0012] According to the invention, the electric motor comprises a drive shaft extending along an axis XI and a drive pinion. This drive pinion meshes with the first gear, which is mounted to rotate freely about an axis X2. This first gear, in turn, meshes with the second gear, which is also mounted to rotate freely about an axis X3. According to a particular feature of the invention, the axes XI, 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 two gear wheels have straight teeth. The teeth can also be helical.

[0014] According to an additional feature of the invention, the two gears have a different number of teeth. Consequently, the two gears also have different diameters. Thus, the angular position of the two gears will be different, which allows for the generation of different signals. These different signals are the basic data for the controller to generate a signal corresponding to an angular position of the torque output element within its actuation range.

[0015] According to another feature of the invention, the two gear wheels are guided in rotation by an intermediate frame.

[0016] 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.

[0017] Advantageously, the electric motor, the motor pinion, the drive means with their magnets, the electronic board with the two sensors, the intermediate frame and at least part of the torque output element are housed in a casing.

[0018] 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.

[0019] The invention also relates to an assembly comprising an actuator according to one of the above characteristics and a controller, said controller being configured to generate a signal corresponding to an angular position of the torque output element over its actuation range from a comparison of the signals generated by the two angular position sensors of each gear.

[0020] Preferably, the controller is located on the electronic board of the actuator.

[0021] Finally, the invention also relates to a method for determining the position angular of the torque output element of the actuator of the assembly mentioned above, the method comprises the following steps: i) retrieval of a first signal associated with the angular position of the first toothed wheel, ii) retrieval of a second signal associated with the angular position of the second toothed wheel, iii) comparison of the two signals by the controller, iv) generation by the controller of a signal corresponding to an angular position of the torque output element on its actuation range.

[0022] Other features and advantages of the invention will become apparent from the following detailed embodiment, with reference to the attached figures:

[0023] [Fig.1] represents a perspective view of the actuator according to the present invention;

[0024] [Fig.2] represents a front view of the actuator according to the present invention;

[0025] [Fig.3] represents a schematic diagram of the controller associated with the actuator according to the present invention;

[0026] [Fig.4] represents a graph of the input and output signals of the controller.

[0027] It should be noted that the figures disclose the invention in sufficient detail for its implementation, and that the figures help to further define the invention if necessary. However, the invention should not be limited to the embodiment disclosed in the description.

[0028] With reference to [Fig. 1] and [Fig. 2], an electromechanical actuator is shown without its housing to better highlight the internal elements. This actuator 1 comprises an electric motor 2 acting on a torque output element 6 suitable for coupling with a moving part in translation of a gearbox. Vehicle transmission. The electric motor 2 is a brushed DC type and comprises a motor shaft extending along an axis XI and a motor pinion 3 fixed to this shaft. The electric motor 2 is axially pressed into the housing (not shown) by a compression plate 21, known per se.

[0029] 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.

[0030] The torque output element 6 is connected to the electric motor 2 by means of a drive. 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 by means of 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 the two gears 4 and 5 have spur gears. The two gears 4 and 5 are guided in rotation by an intermediate frame 20 fixed to the housing (not shown). 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.

[0031] Axes XI, X2, X3 are parallel so that the actuator has a "U" shaped design.

[0032] Each gear 4, 5 has a magnet 41, 51 at one end. These magnets are preferably attached to the gears by snap-fitting via hooks 42, 52. Other means of attaching the magnets are also possible, in particular by gluing. The magnets 41, 51 face two sensors 12, 13 mounted on an electronic board 10. The association of the magnet 41, 51 with its respective sensor 12, 13 makes it possible to detect the angular position of each gear 4, 5. The electronic board 10 also includes a controller 100 for processing the SI and S2 signals generated by the sensors 12, 13. This sensor and its functionalities will be discussed in relation to [Fig. 3] and [Fig. 4].

[0033] A particular aspect of the invention is that the two gears 4 and 5 have a different number of teeth. In this case, the first gear has fewer teeth than the second gear. For example, the first gear 4 has 24 teeth and the second gear 5 has 28 teeth. Because of this difference, the angular position of the two gears 4 and 5 will be different.

[0034] It is thus established when the actuator 1 is in operation, due to the different number of teeth, that the angular position of the two toothed wheels 4, 5 will be different, each toothed wheel 4, 5 generating its own angular position signal SI, S2 via the magnets 41, 51 and the sensors 12, 13. Thus the signal SI is associated with the first toothed wheel 4 and the signal S2 is associated with the second toothed wheel 5.

[0035] Fig. 3 schematically shows how these two input signals are processed by the controller 100. The controller 100 is configured to generate an output signal SF corresponding to the angular position of the torque output element 6 over its actuation range from a comparison of the input signals SI, S2 based on the graph in Fig. 4.

[0036] Figure 4 shows a graph with, in particular, the two input data SI and S2 used to generate the output signal SF. Depending on its angular position, each gear 4, 5 generates a signal SI, S2 whose voltage varies. Due to the different number of teeth, a shift between these two signals is measured, which makes it possible to artificially create an SF signal using a modulo function of the voltage difference between the signals SI and S2 divided by the number of teeth difference between the gears 4, 5.

[0037] Although the invention has been described in connection with a particular embodiment, it is clearly evident that it is by no means limited to it and that it includes all technical equivalents of the means described.

[0038] In the claims, the reference symbols in parentheses should not be interpreted as a limitation of the claim.

Claims

Demands

1. Assembly comprising an electromechanical actuator (1) and a controller (100), said electromechanical actuator (1) comprising an electric motor (2) acting on a torque output element (6) suitable for coupling with a moving part of a vehicle transmission, 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 (4) and a second gear (5), the electric motor (2) comprising a drive shaft extending along an axis XI and a drive pinion (3), this drive pinion (3) meshes with the first gear (4) which is mounted to rotate about an axis X2,This first gear (4) in turn meshes with the second gear (5) which is mounted to rotate about an axis X3. The torque output element (6) is a shaft rotationally linked to the second gear (5) and is configured to rotate about the axis of rotation X3. The actuator (1) further comprises an electronic board (10), including two sensors (12, 13) which each face a magnet (41, 51) associated with each gear (4, 5) in order to detect the angular position of each gear (4, 5). Said controller (100) is configured to generate a signal (SF) corresponding to an angular position of the torque output element (6) over its actuation range from a comparison of the signals (SI, S2) generated by the two sensors (12, 13) of the angular position of each gear (4, 5).

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

3. Assembly according to claim 1 or 2, characterized in that the drive pinion (3) and the two gear wheels (4, 5) have straight or helical teeth.

4. Assembly according to any one of the preceding claims, characterized in that the two gear wheels (4, 5) have a different number of teeth.

5. Assembly according to any one of the preceding claims, characterized in that the two gear wheels (4, 5) are guided in rotation by a frame intermediate (20).

6. Assembly according to claim 5, characterized in that the electric motor (2), the motor pinion (3), the drive means (4, 5) with their magnets (41, 51), the electronic board (10) with the two sensors (12, 13), the intermediate frame (20) and at least part of the torque output element (6) are housed in a casing.

7. A method for determining the angular position of the torque output element (6) of the actuator (1) of the assembly according to any one of the preceding claims, characterized in that the method comprises the following steps: i) retrieval of a first signal (SI) associated with the angular position of the first toothed wheel (4), ii) retrieval of a second signal (S2) associated with the angular position of the second toothed wheel (5), iii) comparison of the two signals (SI, S2) by the controller (100), iv) generation by the controller of a signal (SF) corresponding to an angular position of the torque output element (6) over its actuation range.

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