Electromechanical actuator

Abstract

The present invention relates to an electric motor (3) housed in a housing (2), the electric motor (3) acting on a torque output element adapted to be coupled with an element of a transmission box of a motor vehicle, 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 card (13) located in the housing (2), the electronic card (13) comprises a sensor (14) which faces a magnet (17) mounted on a support (16) coupled to the second end (7b) of the main shaft (7) by means of a first roto-linear mechanism (15), said magnet support (16) being locked in rotation relative to the housing (2) by means of a plate (30) attached and fixed to the housing (2).Figure for abstract: Figure 2.

Description

Title of the invention: Electromechanical actuator

[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, in particular a motor vehicle equipped with an automatic gearbox, for example a hybrid vehicle. The invention also applies to a parking lock system for a reducer associated with an electric vehicle motor. The gearbox or reducer will more generally be called a transmission box. This locking system is better known by its term in English "park-lock" or "parking lock". Such an actuator allows the transmission box to be locked in parking by means of a lever engaging with a toothing of the transmission box.

[0003] The invention also applies to the field of actuators for a system for 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 proposing a complex mechanism for detecting the position of the main shaft with a wheel and worm screw system.

[0005] Patent application FR2212913 in the name of the applicant is also known. The architecture of this actuator has the disadvantage of being complicated to assemble, in particular 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. In addition, 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 comprising an electric motor housed in a housing, the electric motor acting on a torque output element capable of being coupled with an element of a transmission box 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 card located in the housing, the electronic card comprises a sensor which faces a magnet mounted on a support coupled to the second end of the main shaft by means of a first roto-linear mechanism, said magnet support being locked in rotation relative to the housing by means of a plate attached and fixed to the housing.

[0008] This design makes it possible, during assembly of the actuator, to produce a subassembly comprising the torque output element, i.e. the main shaft on which the magnet support is mounted. This subassembly is integrated into the housing and the plate then blocks the rotation of the magnet support relative to the housing, which thus generates the translation of the first roto-linear system along the main shaft.

[0009] According to one aspect of the invention, the first roto-linear mechanism is a screw nut system. The screw part is located on the main shaft, more precisely at one of its ends. The nut part can be directly the magnet support or indirectly linked to the magnet support. Any other type of roto-linear mechanism can be used as a variant, 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 a material with the housing. The housing is for example made of plastic. Preferably, two pins are made of a material with the housing.

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

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

[0013] According to 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 provide plastic-metal contact with the plate. Plastic-metal contact allows for optimized sliding and service life.

[0014] Advantageously, in the assembled configuration the plate is located above the magnet support. This arrangement makes it easier to assemble the actuator.

[0015] According to an additional characteristic of the invention, the housing comprises an axial opening and the magnet support is capable, due to its size, of passing through this opening. This arrangement makes it easier to assemble the actuator.

[0016] According to another characteristic of the invention, the main shaft is connected to the electric motor by means of a pinion wheel system to effect rotation of 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 is straight-toothed.

[0017] Advantageously, a second roto-linear mechanism is coupled to the first end of the main shaft. The second roto-linear mechanism makes it possible to transform the rotary movement of the main shaft into linear movement. The The second roto-linear mechanism is a screw-nut system, the screw part is located on the main shaft, more precisely at one of its ends, and the nut part is a thrust member. Any other type of roto-linear mechanism can be used as an alternative, for example a ball screw system.

[0018] According to a 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 of between 0.1 and 3.

[0019] According to 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 characteristics and advantages of the invention will emerge from the following reading of a detailed example embodiment, with reference to the appended figures:

[0021] [Fig.l] represents a sectional view of an actuator according to the invention;

[0022] [Fig.2] represents a perspective view of the actuator according to the invention;

[0023] [Fig.3] represents another sectional view of the actuator according to the invention;

[0024] [Fig.4] represents a perspective view of the actuator flange;

[0025] [Fig.5] represents a sectional view focused on the actuator flange.

[0026] It should be noted that the figures disclose the invention in a manner sufficiently detailed for its implementation, said figures helping to better define the invention if necessary. The invention should not, however, be limited to the embodiment disclosed in the description.

[0027] In [Fig.l] an electromechanical actuator 1 is illustrated comprising a direct current electric motor 3 housed inside a plastic housing 2. The housing 2 can be fixed to the transmission box by means of fixing eyelets 20. In the upper part, the housing 2 is able to be closed by means of a cover (not shown).

[0028] The electric motor 3 acts on a thrust member 18 configured to perform a predetermined linear movement (an extension and retraction movement) to contact an external mechanism (not shown) in the transmission box.

[0029] 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 one facing the element of the transmission box, 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 mechanism roto-linear 9 is a screw nut system. The first end 7a of the main shaft 7 has an external threaded section which is coupled to a threaded section present in an internal housing of the thrust member 18.

[0030] The main shaft 7 is connected to the electric motor 3 by drive means 4, i.e. a pinion-wheel system for effecting 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.

[0031] The electric motor 3 is controlled by means of an electronic card 13 located in the housing 2.

[0032] To ensure operation of the actuator 1, detection means are provided configured to detect the axial position of the thrust member 18, comprising a Hall effect sensor 14 permanently mounted and connected to the electronic card 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, so that the magnet support can 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.

[0033] With particular reference to the magnet holder 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 holder 16.

[0034] The stroke of the two roto-linear mechanisms 9, 15 is different. In particular, the stroke of the first roto-linear mechanism 15, that is to say the one associated with the sensor 14 and magnet 17 detection system, is smaller 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. In this way, the stroke of the first roto-linear mechanism and the stroke of the second roto-linear mechanism have a ratio of between 0.5 and 0.8. Preferably, the ratio is 0.7.

[0035] Thus, depending on the magnetic field generated by the permanent magnet 17 which is detected by the sensor 14, the system will be aware of the exact position of the thrust member 18.

[0036] 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 and fixed 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 in order to prevent external pollutants from entering the actuator 1.

[0037] [Fig.2] allows a better visualization of the different components of the actuator and in particular the plate 30 which is fixed in the housing 2.

[0038] When assembling the actuator, a sub-assembly is created and comprises the main shaft 7, the magnet support 16 and its magnet 17, the toothed wheel 6, the bearing 12 as well as the flange 10 and the thrust member 18. This sub-assembly is then inserted into the housing 2 through the axial opening 22 concentric with the axis of rotation X. Due to its reduced size, that is to say 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 added and is positioned on the pins 21 which emerge from the housing thanks to openings 31 in the plate 30.

[0039] Once the plate 20 is positioned in the housing along the pins 21, these are deformed by a hot deformation operation in order to create a bead of material which locks the plate 30 in position. This locking of the plate 30 is visible in [Fig. 3]. It is also visible in this figure that the electric motor 3 is held in the housing by a compression plate 40.

[0040] The magnet support 16, in particular the upper area receiving the magnet 17, passes through the plate 30 via an opening 32. The lower area 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 in order to perform the nut function. The magnet support 16, in particular its lower part, comprises two protrusions 81 in the form of wings which come into contact with the plate 30 in order 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 surface 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.

[0041] [Fig.4] and [Fig.5] show in more detail the design of the flange 10. For reasons of optimizing the weight and cost of the actuator, the flange is made of plastic. The process for obtaining this plastic flange does not allow the creation of a groove for inserting an elastic ring necessary for axially locking the bearing 11 in the flange 10. A pin 50 is then radially inserted into an opening 51 of 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 on the housing 2, the pin 50 is radially locked by the housing 2, that is to say it can no longer come out of its housing 51, which ensures optimized locking of the bearing 11.

[0042] Although the invention has been described in connection with a particular embodiment, it is obvious that it is in no way limited thereto and that it includes all the technical equivalents of the means described.

[0043] In the claims, the reference symbols in parentheses should not be interpreted as a limitation of the claim.

Claims

Claims

1. Electromechanical actuator (1) comprising an electric motor (3) housed in a housing (2), the electric motor (3) acting on a torque output element adapted to be coupled with an element of a transmission box of a motor vehicle, 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 card (13) located in the housing (2), the electronic card (13) comprises a sensor (14) which faces a magnet (17) mounted on a support (16) coupled to the second end (7b) of the main shaft (7) by means of a first roto-linear mechanism (15),said magnet support (16) being locked in rotation relative to the housing (2) by means of a plate (30) attached and fixed to the housing (2).,

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

3. Electromechanical actuator (1) according to claim 1 or 2, characterized in that the plate (30) is fixed to the housing (2) by means of at least one centering pin (21) made of the same material as 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 deformation 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 protuberance (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 capable, due to its size, of passing through this 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 (1) by means of a pinion (5) wheel (6) system for rotating the main shaft (7).

8. Electromechanical actuator (1) according to one of the preceding claims, characterized in that a second roto-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 roto-linear mechanism (15) is different from the stroke of the second roto-linear mechanism (9).

10. Electromechanical actuator (1) according to one of the preceding claims, characterized in that the main shaft (7) is guided in rotation 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) fixed to the housing (2).

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