ELECTROMECHANICAL ACTUATOR

Description

[0001] The invention relates to an electromechanical actuator.

[0002] The invention applies more specifically 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 referred to as a transmission. This locking system is better known by its English term. « park-lock » Or « parking lock ». Such an actuator allows the transmission to be locked in parking position by means of a lever that engages with a gear in the transmission.

[0003] The invention also applies to the field of actuators for a system of connecting / disconnecting elements in the transmission of the aforementioned vehicles.

[0004] Actuators of this type are known, for example in document ES1217209UA. This type of actuator has the disadvantage of offering a complex mechanism for detecting the position of the main shaft with a worm gear system.

[0005] It is also known as patent application FR3143079A1 in the name of the applicant. The architecture of this actuator has the disadvantage of being complicated to assemble, particularly the assembly of the first roto-linear system carrying the magnet. Indeed, it is necessary to screw the magnet support inside the actuator from the torque output element, which results in complex handling. Furthermore, the screwing must also be carried out to a specific position, which requires counting the number of rotations.

[0006] It is therefore necessary to propose a system that is simpler to assemble while still being effective.

[0007] Thus, the invention proposes an electromechanical actuator as described in claim 1 comprising a housing and an electric motor housed in the housing, the electric motor acting on a torque output element suitable for coupling with an element of a transmission of a motor vehicle, the torque output element being connected to the electric motor by drive means, the torque output element being a main shaft configured to rotate about its axis of rotation with a first end and a second end, the actuator further comprises an electronic board located in the housing, the electronic board includes a sensor which faces a magnet mounted on a support characterized in that the magnet support is coupled to the second end of the main shaft by means of a first roto-linear mechanism,said magnet support being prevented from rotating relative to the housing by means of a plate attached to and fixed to the housing.

[0008] This design allows, during actuator assembly, the creation of a sub-assembly comprising the torque output element, i.e., the main shaft on which the magnet support is mounted. This sub-assembly is integrated into the housing, and the plate then prevents the magnet support from rotating relative to the housing, thus generating the translation of the first roto-linear system along the main shaft.

[0009] Advantageously, the first roto-linear mechanism is a screw-nut system. The screw part is located on the main shaft, specifically at one of its ends. The nut part can be the magnet support directly or indirectly connected to it. Any other type of roto-linear mechanism can be used as an alternative, for example, a ball screw system.

[0010] Advantageously, the plate is fixed to the housing by means of at least one centering pin made of the same material as the housing. The housing is, for example, made of plastic. Preferably, two pins are made of the same material as the housing.

[0011] According to a preferred embodiment of the invention, the centering pin is capable of being deformed by a hot deformation or welding operation once the plate has been inserted.

[0012] According to a preferred embodiment of the invention, the plate is made of metal. Metal has the advantage of absorbing the forces generated by the magnet support without deforming.

[0013] According to a preferred embodiment of the invention, the magnet support comprises at least one protrusion in contact with the plate. Preferably, two protrusions extend radially on either side of the magnet support. The magnet support is preferably made of plastic to achieve a plastic-to-metal contact with the plate. This plastic-to-metal contact allows for smooth sliding and optimized lifespan.

[0014] Advantageously, in the assembled configuration, the plate is positioned above the magnet support. This arrangement facilitates the assembly of the actuator.

[0015] According to an additional feature of the invention, the housing includes an axial opening, and the magnet support is sized to pass through this opening. This arrangement facilitates the assembly of the actuator.

[0016] According to another feature of the invention, the main shaft is connected to the electric motor by means of a pinion-wheel system to rotate the main shaft. The pinion is located on the shaft of the electric motor, and the wheel is located on the torque output element, i.e., the main shaft. Preferably, the pinion-wheel system has spur gears.

[0017] Advantageously, a second roto-linear mechanism is coupled to the first end of the main shaft. This second roto-linear mechanism transforms the rotary motion of the main shaft into linear motion. The second roto-linear mechanism is a screw-nut system; the screw portion is located on the main shaft, specifically at one end, and the nut portion acts as a thrust element. Any other type of roto-linear mechanism can be used as an alternative, for example, a ball screw system.

[0018] According to a particular feature of the invention, the stroke of the first roto-linear mechanism is different from the stroke of the second roto-linear mechanism. For example, the stroke of the first roto-linear mechanism and the stroke of the second roto-linear mechanism have a ratio between 0.1 and 3.

[0019] According to a preferred embodiment of the invention, the main shaft is guided in rotation by a bearing, the inner ring of the bearing is in contact with the main shaft and the outer ring of the bearing is in contact with a flange fixed to the housing.

[0020] Other features and advantages of the invention will become apparent from the following detailed example of an embodiment, with reference to the attached figures: there [ Figure 1 ] represents a cross-sectional view of an actuator according to the invention; the [ Figure 2 ] represents a perspective view of the actuator according to the invention; the [ Figure 3 ] represents another cross-sectional view of the actuator according to the invention; the [ Figure 4 ] represents a perspective view of the actuator flange; the [ Figure 5 ] represents a cross-sectional view focused on the actuator flange.

[0021] 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.

[0022] On the [ Figure 1 An electromechanical actuator 1 is illustrated, comprising a DC electric motor 3 housed inside a plastic casing 2. The casing 2 can be attached to the transmission via mounting eyelets 20. The upper part of the casing 2 is designed to be closed by means of a cover (not shown).

[0023] The electric motor 3 acts on a thrust member 18 configured to perform a predetermined linear displacement (an extension and retraction movement) to come into contact with an external mechanism (not shown) in the transmission box.

[0024] The thrust member 18 is connected to the electric motor 3 via a main shaft 7 axially aligned with the thrust member 18. The main shaft 7 is preferably made of metal and is configured to rotate about its axis of rotation X. A first end 7a of the main shaft 7, i.e., the end facing the transmission element, is coupled to the thrust member 18 by a roto-linear mechanism 9, so that the thrust member 18 can move in translation relative to the main shaft 7 when the main shaft 7 is rotating. The roto-linear mechanism 9 is a screw-nut system. The first end 7a of the main shaft 7 has an external threaded section that is coupled to a threaded section in an internal housing of the thrust member 18.

[0025] The main shaft 7 is connected to the electric motor 3 by means of drive 4, i.e. a pinion-wheel system to perform the rotation of the main shaft 7. The toothed wheel 6 of the pinion-wheel system is fixedly coupled to the main shaft 7 which engages with a pinion 5 mounted on a shaft of the electric motor 3.

[0026] The electric motor 3 is controlled by means of an electronic board 13 located in the housing 2.

[0027] To ensure the operation of the actuator 1, detection means are provided, configured to detect the axial position of the thrust member 18. These means include a permanently mounted Hall effect sensor 14 connected to the electronic board 13 and a permanent magnet 17. This magnet 17 is mounted on a support 16, which is coupled to the main shaft 7 by means of a roto-linear mechanism 15. This allows the magnet support to move in translation relative to the main shaft 7 when the main shaft 7 is rotating. The roto-linear mechanism 15 is a screw-nut system.

[0028] With regard more specifically to the magnet support 16, it comprises a plastic body having an upper area receiving the magnet 17 and a lower area in the form of a threaded nut configured to engage with a threaded section of the second end 7b of the main shaft 7. The threaded nut is a metal insert 19 overmolded with the magnet support 16.

[0029] The stroke of the two roto-linear mechanisms 9 and 15 is different. In particular, the stroke of the first roto-linear mechanism 15, that is, the one associated with the sensor 14 and magnet 17 detection system, is shorter than the stroke of the second roto-linear mechanism 9 of the thrust member 18. For example, the stroke of the first roto-linear mechanism 15 is 14 mm and the stroke of the second roto-linear mechanism 9 is 22 mm. Thus, the stroke of the first roto-linear mechanism and the stroke of the second roto-linear mechanism have a ratio between 0.5 and 0.8. Preferably, the ratio is 0.7.

[0030] Thus, depending on the magnetic field generated by the permanent magnet 17 which is detected by the sensor 14, the system will know the exact position of the thrust member 18.

[0031] The main shaft 7 is supported and guided in rotation by a double-row ball bearing 11. The inner ring of the bearing 11 is in contact with the main shaft 7, and the outer ring of the bearing 11 is in contact with the housing 2 and a flange 10 attached to the housing 2. The flange 10 also serves as a guide for the second roto-linear mechanism 9. A lip seal 12 is housed in the flange 10 and is located axially between the bearing 11 and the thrust member 18 to prevent external contaminants from entering the actuator 1.

[0032] There [ Figure 2 ] allows for a better visualization of the different components of the actuator and in particular the plate 30 which is fixed in the housing 2.

[0033] During the assembly of the actuator, a subassembly is created comprising the main shaft 7, the magnet support 16 and its magnet 17, the gear 6, the bearing 12, as well as the flange 10 and the thrust member 18. This subassembly is then inserted into the housing 2 through the axial opening 22 concentric with the axis of rotation X. Due to its small size, i.e. in width and height, the magnet support 16 is able to pass through this opening 22. Once the magnet support is inside the housing 2, a plate 30 is attached and positioned on the pins 21 which protrude from the housing through openings 31 in the plate 30.

[0034] Once plate 20 is positioned in the housing along the pins 21, these are deformed by a hot forming operation to create a bead of material that locks plate 30 in position. This locking of plate 30 is visible in the [ Figure 3 It is also visible in this figure that the electric motor 3 is held in the housing by a compression plate 40.

[0035] The magnet support 16, in particular the upper region receiving the magnet 17, passes through the plate 30 via an opening 32. The lower region of the magnet support 16 is configured to engage with a threaded section of the second end 7b of the main shaft 7 via the metal insert 19 to perform the nut function. The magnet support 16, in particular its lower part, includes two wing-shaped protrusions 81 that contact the plate 30 to perform the anti-rotation function. The two protrusions 81 extend radially on either side of the magnet support 16. Contact is made by a linear pin 82 which is located on each protrusion 81 in order to minimize the contact area between the magnet support 16 and the plate 30. The plate 30 is metallic and the magnet support 16 is made of plastic to make a plastic-metal contact.

[0036] THE [ Figure 4 ] And [ Figure 5[ ] show in more detail the design of the flange 10. For reasons of weight and cost optimization of the actuator, the flange is made of plastic. The process of obtaining this plastic flange does not allow for the creation of a groove for inserting a retaining ring necessary for the axial locking of the bearing 11 in the flange 10. A pin 50 is therefore radially inserted into an opening 51 in the flange. The pin 50 is substantially U-shaped. Once the pin 50 is mounted in the flange 10, the bearing 11 is axially locked. Once the flange 10 is assembled onto the housing 2, the pin 50 is radially locked by the housing 2, i.e., it can no longer come out of its housing 51, which ensures optimized locking of the bearing 11.

[0037] 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.

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

Claims

1. Electromechanical actuator (1) comprising a housing (2) and an electric motor (3) housed within the housing (2), the electric motor (3) acting on a torque output element capable of being coupled to an element of a motor vehicle transmission, the torque output element being connected to the electric motor (3) by drive means (4), the torque output element being a main shaft (7) configured to rotate about its axis of rotation (X) with a first end (7a) and a second end (7b), the actuator (1) further comprises an electronic board (13) located within the housing (2), the electronic board (13) includes a sensor (14) that faces a magnet (17) mounted on a support (16), characterized in that the magnet support (16) is coupled to the second end (7b) of the main shaft (7) by means of a first rotary-linear mechanism (15), said magnet support (16) being locked against rotation relative to the housing (2) by means of a plate (30) attached to and secured to the housing (2).

2. Electromechanical actuator (1) according to claim 1, characterized in that the first rotary-linear mechanism (15) is a screw-nut system.

3. Electromechanical actuator (1) according to claim 1 or 2, characterized in that the plate (30) is secured to the housing (2) by means of at least one centering pin (21) formed integrally with the housing (2).

4. Electromechanical actuator (1) according to claim 2, characterized in that the centering pin (21) is capable of being deformed by a hot forming or welding operation once the plate (30) is inserted.

5. Electromechanical actuator (1) according to one of the preceding claims, characterized in that the magnet support (16) comprises at least one protrusion (81) in contact with the plate (30).

6. Electromechanical actuator (1) according to one of the preceding claims, characterized in that the housing (2) comprises an axial opening (22) and the magnet support (16) is sized to pass through said opening (22).

7. Electromechanical actuator (1) according to one of the preceding claims, characterized in that the main shaft (7) is connected to the electric motor (3) by means of a pinion (5)-gear (6) system to effect the rotation of the main shaft (7).

8. Electromechanical actuator (1) according to one of the preceding claims, characterized in that a second rotary-linear mechanism (9) is coupled to the first end (7a) of the main shaft (7).

9. Electromechanical actuator (1) according to claim 8, characterized in that the stroke of the first rotary-linear mechanism (15) is different from the stroke of the second rotary-linear mechanism (9).

10. Electromechanical actuator (1) according to one of the preceding claims, characterized in that the main shaft (7) is rotatably guided by a bearing (11), the inner ring of the bearing (11) is in contact with the main shaft (7) and the outer ring of the bearing (11) is in contact with a flange (10) secured to the housing (2).