Electromechanical actuator
By designing an electromechanical actuator including an electric motor, Hall effect sensor and permanent magnet, the complexity and cost of actuators in existing parking lock systems is solved, and simple, economical and accurate spindle position measurement is achieved.
Patent Information
- Application Number
- CN202380075211.9
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Priority Date
- 2022-12-07
- Filing Date
- 2023-11-16
- Publication Date
- 2025-05-27
AI Technical Summary
The actuators in existing parking lock systems use complex worm gear and worm systems to detect spindle positions, resulting in high cost, complex implementation, and lack of simple and economical solutions.
An electromechanical actuator is designed, including an electric motor, torque output element and electronic board, and the spindle position is detected using Hall effect sensors and permanent magnets, and position measurement is achieved through a simple screw-nut system.
The spindle position is achieved using a simple and inexpensive design, reducing system costs and simplifying the implementation process while ensuring measurement accuracy.
Smart Images
Figure CN120051645A_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The present invention relates to an electromechanical actuator.
[0002] More specifically, the present invention is applied to the field of actuators for parking lock systems for immobilizing the gearbox of a vehicle, particularly a motor vehicle equipped with an automatic gearbox, such as a hybrid vehicle. The present invention is also applied to parking lock systems for immobilizing a reduction gear associated with an electric vehicle motor. The gearbox or reduction gear is generally referred to as a transmission gearbox. This locking system is better known as a parking lock or a parking brake. Such an actuator allows the transmission gearbox to be immobilized when parking by means of a lever that engages with the gear set of the transmission gearbox.
[0003] The present invention is also applied to the field of actuators for systems for connecting / disconnecting elements in the transmission gearbox of the above-mentioned vehicle. BACKGROUND OF THE INVENTION
[0004] This type of actuator is known, for example, from document ES1217209UA. The drawback of this type of actuator is that it proposes a complex mechanism using a worm gear system to detect the position of the main shaft.
[0005] Therefore, it is necessary to propose a system that is less costly, simpler to implement, and still effective. SUMMARY OF THE INVENTION
[0006] Therefore, the present invention proposes an electromechanical actuator that includes an electric motor housed in a housing. The electric motor acts on a torque output element that can be coupled to an element of a motor vehicle transmission. The torque output element is connected to the electric motor by a drive device. The torque output element is a main shaft that is configured to rotate about its axis of rotation and has a first end and a second end. The actuator also includes an electronic board located inside the housing. The electronic board includes a sensor facing a magnet. The magnet is mounted on a support that is coupled to the second end of the main shaft by a first rotary linear mechanism.
[0007] This design allows for a simple and inexpensive design to reliably measure the position of the main shaft.
[0008] According to one aspect of the present invention, the sensor is preferably a Hall effect sensor, and the magnet is a permanent magnet and is polarized.
[0009] Advantageously, the first rotary linear mechanism is a screw-nut system. The screw part is located on the main shaft, more specifically at its second end. The nut part can directly be the magnet support, or can be indirectly connected to the magnet support. Any other type of rotary linear mechanism can be used as an alternative, such as a ball screw system.
[0010] According to the present invention, the main shaft is connected to an electric motor by a pinion-rotor system so as to rotate the main shaft. The pinion is on the shaft of the electric motor, and the rotor is on the torque output element, i.e., the main shaft. Preferably, the pinion-rotor system has straight-cut teeth.
[0011] According to the present invention, a first rotary linear mechanism is coupled to the surface of the housing so as to perform an anti-rotation function. More specifically, the nut portion of the first rotary linear mechanism is coupled to the surface of the housing.
[0012] According to an alternative embodiment, the first rotary linear mechanism is associated with the magnet support by a cam-slot system. This enables the linear movement of the first rotary linear mechanism to be converted into the rotation of the magnet support.
[0013] According to an additional feature of the present invention, a second rotary linear mechanism is coupled to the first end of the main shaft. The second rotary linear mechanism is capable of converting the rotational movement of the main shaft into a linear movement. The second rotary linear mechanism is a screw-nut system, with the screw portion on the main shaft, more specifically at its first end, and the nut portion being a thrust member. Any other type of rotary linear mechanism can be used as an alternative, such as a ball screw system.
[0014] According to another feature of the present invention, the stroke of the first rotary linear mechanism is different from the stroke of the second rotary linear mechanism. For example, the ratio between the stroke of the first rotary linear mechanism and the stroke of the second rotary linear mechanism is between 0.1 and 3.
[0015] In particular, the stroke of the first rotary linear mechanism can be shorter than the stroke of the second rotary linear mechanism. This feature enables the reduction of the stroke of the first rotary linear mechanism related to the magnet support and the use of standard sensors.
[0016] Alternatively, the stroke of the first rotary linear mechanism can be longer than the stroke of the second rotary linear mechanism. This feature enables the improvement of the measurement accuracy.
[0017] Advantageously, the main shaft is rotationally guided by a rolling bearing, with the inner ring of the rolling bearing in contact with the main shaft and the outer ring of the rolling bearing in contact with the housing and the flange fixed to the housing. The rolling bearing is preferably a double-row ball bearing because the main shaft bears a large axial load of approximately 700 N.
[0018] According to a specific feature of the present invention, the electric motor includes a front face and a back face facing the drive device, and the housing includes a removable plug at the back of the electric motor. The removal of the plug advantageously allows access to the motor in order to perform a manual operation of engaging or disengaging the locking system. Description of the Drawings
[0019] With reference to the accompanying drawings, other features and advantages of the present invention will become apparent by reading the following detailed description of exemplary embodiments:
[0020] Figure 1 is a cross-sectional view of an actuator according to the first embodiment;
[0021] Figure 2 is Figure 1 a perspective and partial cross-sectional view of the actuator;
[0022] Figure 3 is a cross-sectional view of an actuator according to the second embodiment;
[0023] Figure 4 is a top view of an actuator without a cover according to the third embodiment;
[0024] Figure 5 is Figure 4 a perspective and partial cross-sectional view of the actuator.
[0025] It should be noted that the drawings disclose the implementation of the present invention in a sufficiently detailed manner, and the drawings help to better define the present invention as needed. However, the present invention should not be limited to the embodiments disclosed in the specification. Detailed Description of the Invention
[0026] In Figure 1 the first embodiment shown, the electromechanical actuator 1 includes a DC electric motor 3 housed inside a housing 2 made of, for example, aluminum or plastic. The electric motor 3 includes a front face 3a and a back face 3b. The housing 2 includes a removable plug 30 at the back face 3b of the electric motor 3. The housing 2 can be fixed to the transmission gearbox by a fixing ring 20. At its upper part, the housing 2 is closed by a cover 40, which includes a gas-permeable but liquid-impermeable membrane 50. The cover 40 includes an electrical connector so that the actuator 1 can be powered.
[0027] The electric motor 3 acts on a thrust member 18 configured to perform a predetermined linear motion (extension and retraction motion) in order to contact an external mechanism (not shown) in the transmission gearbox.
[0028] The thrust member 18 is connected to the electric motor 3 by a main shaft 7, which is 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. The first end 7a of the main shaft 7, i.e., the end facing the element of the transmission gearbox, is connected to the thrust member 18 by a rotary linear mechanism 9 such that when the main shaft 7 rotates, the thrust member 18 can translate relative to the main shaft 7 and rotate simultaneously. The rotary linear mechanism 9 is a screw-nut system. The first end 7a of the main shaft 7 has an external threaded portion, which is connected to a threaded portion inside the cavity of the thrust member 18.
[0029] The main shaft 7 is connected to the electric motor 3 via a drive means 4 (i.e., a pinion - runner system) so as to rotate the main shaft 7. The toothed runner 6 of the pinion - gear system is fixedly coupled to the main shaft 7, and the main shaft 7 engages with a pinion 5 mounted on the shaft of the electric motor 3.
[0030] The electric motor 3 is controlled by an electronic board 13 located in the housing 2.
[0031] In order to operate the actuator 1, detecting means configured to detect the axial position of the thrust member 18 are provided, and these means include a permanently mounted Hall - effect sensor 14 and a permanent magnet 17 connected to the electronic board 13. The magnet 17 is mounted on a support 16, and the support 16 is coupled to the main shaft 7 via a rotary - linear mechanism 15 such that when the main shaft 7 rotates, the magnet support can translate relative to the main shaft 7. The rotary - linear mechanism 15 is a screw - nut system.
[0032] More specifically, with respect to the magnet support 16, it includes a plastic body provided with an upper region for receiving the magnet 17 and a lower region in the form of a threaded nut configured to engage with the threaded portion of the second end 7b of the main shaft 7. The magnet support 16 is preferably clamped to the threaded nut.
[0033] The strokes of the two rotary - linear mechanisms 9, 15 are different. In particular, the stroke of the first rotary - linear mechanism 15, i.e., the stroke associated with the detection system including the sensor 14 and the magnet 17, is shorter than the stroke of the second rotary - linear mechanism 9 for the thrust member 18. For example, the stroke of the first rotary - linear mechanism 15 is 14 mm, while the stroke of the second rotary - linear mechanism 9 is 22 mm. Thus, the ratio between the stroke of the first rotary - linear mechanism and the stroke of the second rotary - linear mechanism is between 0.5 and 0.8. This ratio is preferably 0.7.
[0034] Therefore, based on the magnetic field generated by the permanent magnet 17 and detected by the sensor 14, the system will know the exact position of the thrust member 18.
[0035] The main shaft 7 is supported and rotationally guided by a double - row ball bearing 11. The inner ring of the rolling bearing 11 contacts the main shaft 7, and the outer ring of the rolling bearing 11 contacts the housing 2 and a flange 10 attached and fixed to the housing 2. The flange 10 is also used to guide the second rotary - linear mechanism 9. A lip seal 12 is housed in the flange 10 and axially positioned between the rolling bearing 11 and the thrust member 18 to prevent external contaminants from entering the actuator 1.
[0036] Figure 2Provides a better visual effect of the magnet support 16, especially the upper region that houses the magnet 17 and the lower region in the form of a threaded nut configured to engage with the threaded portion of the second end 7b of the main shaft 7. The magnet support 16 is substantially T-shaped, and the two arms of the T-shape of the magnet support 16 contact the two planar surfaces 8 of the housing 2 to perform an anti-rotation function. This contact is linear with the protrusion 81. The housing 2 thus includes two planar surfaces 8 along which the two arms of the magnet support 16 slide. The magnet 17 is located on one of the two arms of the support 16.
[0037] Different from the first embodiment, Figure 3 The second embodiment shown does not include a second rotary linear mechanism. In other words, the first end 7a of the main shaft 7 does not include a screw thread but simply has a surface capable of contacting an external mechanism. Since Figure 3 the other elements cited in Figure 1 and Figure 2 are similar to the elements in
[0038] Figure 4 they will not be described herein again.
[0039] Figure 5 Provides a better visual effect of the cam-slot system between the first rotary linear mechanism 15 and the magnet support 161. It can be seen that the magnet support 161 is partially housed in the recess of the housing 2, thereby preventing the translational movement of the magnet support 161 and thus forcing it to pivot about the axis Z. The slot 162 of the magnet support 161 is elliptical. The roller cam 151 is integral with the threaded nut portion of the first rotary linear mechanism 15. In operation, when the threaded nut portion of the first rotary linear mechanism 15 achieves translational movement, the magnet support 161 pivots about the axis Z. Therefore, the position of the thrust member can be obtained by detecting the rotation of the magnet 17 associated with the sensor 14, which is not shown in this figure.
[0040] Although the invention has been described in connection with two specific embodiments, it is obvious that the invention is in no way limited thereto, and that the invention includes all technical equivalents of the means described.
[0041] In the claims, reference signs placed between parentheses shall not be construed as limiting the claim.
Claims
1. An electromechanical actuator (1, 1', 1"), comprising an electric motor (3) housed in a housing (2), the electric motor (3) acting on a torque output element of an element that can be coupled to a transmission gearbox of a motor vehicle, the torque output element being connected to the electric motor (3) by a drive means (4), the torque output element being a main shaft (7) configured to rotate about its axis of rotation (X) and having a first end (7a) and a second end (7b), the actuator (1, 1') further comprising an electronic board (13) located inside the housing (2), the electronic board (13) including a sensor (14) facing a magnet (17), the magnet being mounted on a support (16, 161), the support (16, 161) being coupled to the second end (7b) of the main shaft (7) by a first rotary-linear mechanism (15).
2. The electromechanical actuator (1, 1', 1") according to claim 1, characterized in that, the main shaft (7) is connected to the electric motor (1) by a pinion (5)-runner (6) system so as to rotate the main shaft (7).
3. The electromechanical actuator (1, 1', 1") according to claim 1 or 2, characterized in that, the first rotary-linear mechanism (15) is coupled to a surface (8) of the housing (2) so as to perform an anti-rotation function.
4. The electromechanical actuator (1") according to any one of the preceding claims, characterized in that, the first rotary-linear mechanism (15) is associated with the magnet support (161) by a cam-slot system (151, 162).
5. The electromechanical actuator (1, 1', 1") according to any 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).
6. The electromechanical actuator (1, 1', 1") according to claim 5, characterized in that, the stroke of the first rotary-linear mechanism (15) is different from the stroke of the second rotary-linear mechanism (9).
7. The electromechanical actuator (1, 1', 1") according to claim 5 or 6, characterized in that, the stroke of the first rotary-linear mechanism (15) is shorter than the stroke of the second rotary-linear mechanism (9), or the stroke of the first rotary-linear mechanism (15) is longer than the stroke of the second rotary-linear mechanism (9).
8. The electromechanical actuator (1, 1', 1") according to any one of the preceding claims, characterized in that, the main shaft (7) is rotationally guided by a rolling bearing (11), the inner ring of the rolling bearing (11) being in contact with the main shaft (7), and the outer ring of the rolling bearing (11) being in contact with the housing (2) and a flange (10) fixed to the housing (2).
9. The electromechanical actuator (1, 1', 1") according to claim 8, characterized in that, the rolling bearing (11) is a double-row ball bearing.
10. The electromechanical actuator (1, 1', 1") according to any one of the preceding claims, characterized in that, The electric motor (3) includes a front face (3a) and a back face (3b) facing the drive device (4), and the housing (2) includes a removable plug (30) at the back face of the electric motor (3b).