Actuator with low system friction torque

Abstract

The utility model provides an actuator with low system friction torque. The actuator comprises a motor shaft (1); the output gear (2) is arranged on the motor shaft (1) through a rolling bearing (3); a gear drive (2a) for transmitting a rotational movement of the motor shaft (1) to the output gear (2); a first limiting structure (4) is arranged at the end (1a), used for containing the rolling bearing (3), of the motor shaft, a second limiting structure (5) is arranged on the side, facing the rolling bearing, of the output gear (2), and the rolling bearing is axially fixed to the motor shaft through cooperation of the first limiting structure and the second limiting structure.

Description

Technical Field

[0001] This utility model relates to the field of actuator technology, and in particular to an actuator with low system friction torque. Background Technology

[0002] Currently, the output shaft (motor shaft / motor output shaft) and gear output shaft of the permanent magnet linear actuator (also known as PLA motor) of brushless DC motor (BLDC) are located on different parts, and the rotation reference is not unified. This can easily cause the motor output shaft and gear output shaft to deviate (i.e. there is an interaction force between the two), resulting in large internal friction force, which in turn leads to large system friction torque and large positioning torque of the actuator.

[0003] Furthermore, in current permanent magnet linear actuators, the motor output shaft and output gear operate on a contact friction method, resulting in high frictional torque. Additionally, the sensor magnet on the motor output shaft is mounted on the output gear. After assembly, the output gear tends to move up and down along the Z-axis (the axial direction of the motor output shaft), causing the sensor to fail to accurately capture the signal from the sensor magnet on the output gear, leading to initialization failure.

[0004] Current motor shafts are generally designed with ball joints, which have high tolerance precision, complex processing technology, and high manufacturing costs. Furthermore, the ball joint and the output gear are in constant rotational contact during operation, resulting in dry friction, high frictional resistance, and short lifespan. In addition, the surface of the ball joint requires special hardening treatment, which is costly. Utility Model Content

[0005] In order to overcome at least one of the above problems, the purpose of this invention is to provide an actuator with an improved design that has a lower system friction torque.

[0006] Therefore, this utility model provides an actuator with low system friction torque, the actuator comprising: a motor shaft; an output gear, the output gear being mounted to the motor shaft via a rolling bearing; a gear transmission mechanism for transmitting the rotational motion of the motor shaft to the output gear; a first limiting structure being provided at one end of the motor shaft for receiving the rolling bearing, and a second limiting structure being provided on the side of the output gear facing the rolling bearing, wherein the rolling bearing is axially fixed on the motor shaft through the cooperation of the first limiting structure and the second limiting structure.

[0007] The actuator configured as described above reduces friction between the motor shaft and the output gear by using rolling bearings between them, instead of frictional operation. This reduces the positioning torque of the actuator. In this configuration, the rolling bearings reduce friction through rolling, bear the load transmitted by the output gear, and ensure precise alignment and smooth operation between the motor shaft and the output gear. This significantly improves the efficiency of the gear transmission system, reduces energy loss and wear, extends component life, and ultimately enhances the operational stability and reliability of the entire mechanical system.

[0008] According to a preferred embodiment of the present invention, the rolling bearing includes an inner ring and an outer ring; the first limiting structure includes a first step portion disposed on the motor shaft and a retaining ring spaced apart from the first step portion, for axially fixing the inner ring of the bearing; and the output gear has a mounting hole on the side facing the ball bearing, wherein the mounting hole is a stepped hole, and the second limiting structure is a second step portion of the stepped hole, for axially fixing the outer ring of the bearing.

[0009] According to one aspect of this utility model, the stepped hole includes a first hole segment with a first diameter and a second hole segment with a second diameter, wherein the first diameter is larger than the second diameter; and the output gear is press-fitted onto the outer ring of the ball bearing through the first hole segment.

[0010] According to a preferred embodiment of the present invention, one end of the motor shaft is configured as a non-spherical end, which extends into the second hole section and is clearance-fitted with the second hole section.

[0011] In one embodiment of this utility model, the stepped hole further includes a third hole segment located between the first hole segment and the second hole segment. The third hole segment has a third diameter, which is greater than the second diameter and less than the first diameter, wherein the retaining spring is located within the third hole segment.

[0012] According to one aspect of the present invention, the actuator further includes a printed circuit board, a position sensor for determining the angular position of the output gear, and a sensor magnet opposite to the position sensor, wherein the position sensor is fixedly mounted on the side of the printed circuit board facing the output gear, and the sensor magnet is fixedly mounted to the output gear.

[0013] In one embodiment of this invention, the sensor magnet is fixedly mounted to the output gear by means of a pin and an opening provided in the output gear.

[0014] Advantageously, the position sensor and the sensor magnet are arranged with a gap of 3 mm to 4.24 mm, for example, 3.5 mm.

[0015] According to one aspect of this utility model, the rolling bearing can be a deep groove ball bearing, a tapered roller bearing, an angular contact bearing, or a cylindrical roller bearing. Preferably, the rolling bearing is a deep groove ball bearing, which is suitable for bearing radial loads and relatively small axial loads, has a simple structure, and is suitable for high-speed operation.

[0016] In one embodiment of this utility model, the gear transmission mechanism includes a pinion fixedly mounted to the motor shaft and a transmission gear meshing with the pinion. The transmission gear meshes with an output gear, thereby transmitting the rotational motion of the motor shaft to the output gear.

[0017] Due to the adoption of the above technical solution, the actuator of this utility model can produce at least one of the following beneficial technical effects: it has low frictional torque, which reduces energy loss and improves the overall efficiency of the mechanical system; the reduction of frictional torque means that the heat generated by the system is reduced, thereby avoiding overheating and protecting the equipment; low friction can reduce wear and extend the service life of mechanical parts; systems with less friction generally operate more smoothly, and the noise and vibration are relatively low; by fixing the output gear on the motor shaft through the rolling bearing, the distance between the sensor magnet and the position sensor can be fixed, thereby ensuring the positional accuracy of the client output shaft fixedly connected to the output gear and avoiding initialization failure. Attached Figure Description

[0018] Referring to the accompanying drawings and reading the following detailed description, further features and advantages of this utility model will become clearer:

[0019] Figure 1 A cross-sectional view of an actuator according to an embodiment of the present invention is shown;

[0020] Figure 2 for Figure 1 The enlarged view of section B shown;

[0021] Figure 3 for Figure 2 The enlarged view of section C shown; and

[0022] Figure 4 For use Figure 1 A schematic diagram of one embodiment of the output gear of the actuator shown. Detailed Implementation

[0023] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. The descriptions of orientations used in the following description, such as "upper," "lower," "inner," and "outer," are for convenience only unless explicitly stated otherwise and are not intended to limit the technical solution of the present invention. Furthermore, terms such as "first" and "second" are used below to describe elements of this application; these terms are only used to distinguish individual elements and are not intended to limit the nature, sequence, order, or number of these elements. Additionally, it should be noted that in this specification, the same technical features are represented by the same or similar reference numerals.

[0024] In this article, "actuator" is primarily used for parking, clutching, or shifting gears in automobiles, but it applies to all applications involving parking (locking), clutching, and shifting, such as gasoline-powered vehicles, hybrid vehicles, pure electric vehicles, and other automated devices. "Actuator" can also be replaced with "drive".

[0025] In this article, "low system friction torque" refers to a low resistance torque generated by friction in a mechanical system. This means that the various components in the system (such as bearings, gears, shafts, transmission devices, etc.) encounter very little friction during operation, thereby reducing energy loss, improving efficiency, and reducing heat generation and wear.

[0026] In this application, the "motor shaft" is one of the core components of the electric actuator, and it provides power mainly in the following ways: providing rotational motion, the motor shaft transmits the rotational power of the motor to the reducer or other transmission device, and during the rotation, the rotational motion is converted into the required linear motion (such as lifting, pushing and pulling) through the transmission device; driving the transmission system, the motor shaft is connected to the transmission system such as gears, screws or belts, and when rotating, greater torque or motion conversion is achieved through these mechanical components.

[0027] Figure 1 A cross-sectional view of an embodiment of an actuator with low system friction torque according to the present invention is shown. As can be seen from the figure, the actuator 100 includes a housing 10, a motor shaft 1, a gear transmission mechanism 2a, and an output gear 2 housed within a cavity defined by the housing 10. The output gear 2 is mounted to the motor shaft 1 via rolling bearings 3. The gear transmission mechanism 2a transmits rotational motion of the motor shaft to the output gear 2. A client output shaft (not shown) is fixedly connected to the output gear, for example, via a spline connection. The gear transmission mechanism 2a includes a pinion 2a1 fixedly mounted to the motor shaft 1 and a transmission gear 2a2 meshing with the pinion, which meshes with the output gear 2.

[0028] Advantageously, in order to prevent the output gear, especially the client output shaft fixedly connected to the output gear, from moving up and down along the axial direction of the motor shaft 1, a first limiting structure 4 is provided at one end 1a of the motor shaft for receiving the rolling bearing 3, and a second limiting structure 5 is provided on the side of the output gear 2 facing the rolling bearing. The rolling bearing is axially fixed on the motor shaft by the cooperation of the first limiting structure and the second limiting structure, that is, it cannot move in the axial direction.

[0029] In this embodiment, by replacing the contact friction operation in the existing actuator with a rolling bearing between the motor shaft and the output gear, the motor shaft and the output gear (client output shaft) rotate along the same axis of rotation, that is, rotate on the same shaft. This reduces the dimensional chain / dimensional control, lowers the interaction force inside the system, reduces the internal system friction, and thus reduces the positioning torque of the actuator.

[0030] In a preferred embodiment, the rolling bearing 3 is preferably a deep groove ball bearing, which includes an inner ring 31 and an outer ring 32. Deep groove ball bearings are typically made of steel, stainless steel, ceramic, or other materials, and can be sealed or lubricated according to different application requirements to extend their service life and improve performance. Deep groove ball bearings are suitable for high-speed rotation, operate smoothly, are easy to maintain, have a long service life, and have a simple structure and low cost. Those skilled in the art will understand that rolling bearings can also be tapered roller bearings, angular contact bearings, or cylindrical roller bearings.

[0031] See Figure 2 and Figure 3 The first limiting structure 4 includes a first stepped portion 41 disposed on the motor shaft and a retaining ring 42 spaced apart from the first stepped portion, for axially fixing the bearing inner ring 31. See also Figure 4 The output gear 2 has a mounting hole 20 on the side facing the ball bearing. This mounting hole is a stepped hole, and the second limiting structure 5 is the second step of the stepped hole, used for axially fixing the outer ring 32 of the bearing. In a preferred embodiment, the stepped hole includes a first hole segment 21 with a first diameter, a second hole segment 22 with a second diameter, and a third hole segment 23 with a third diameter. The first diameter is larger than the second diameter, the third diameter is smaller than the first diameter but larger than the second diameter, and the third hole segment 23 is located between the second and third hole segments. During assembly, the rolling bearing 3 is first fixed, specifically by press-fitting it onto the motor shaft 1, and then the output gear is pressed, for example, onto the outer ring 32 of the rolling bearing 3 through the first hole segment 21.

[0032] In a preferred embodiment, the end 1a of the motor shaft 1 to be connected to the output gear 2 is constructed as a non-spherical end, such as the cylindrical and rounded end shown in the figure. In the assembled state, the non-spherical end extends into the second hole segment and has a clearance fit with the second hole segment. In this embodiment, the motor shaft is designed with a non-spherical end, which has low tolerance accuracy, simple processing technology, and relatively low manufacturing cost. Furthermore, the clearance fit between the non-spherical end and the output gear results in frictionless rotation during movement, which can improve service life.

[0033] In one embodiment of the actuator according to this utility model, a printed circuit board 7, a position sensor 6, and a sensor magnet are also included. The position sensor 6 is fixedly mounted on the side of the printed circuit board 7 facing the output gear and is used to determine the angular position of the output gear. The sensor magnet 6a is fixedly mounted to the output gear 2 by, for example, a pin 61 engaging with an opening 23a provided in the output gear 2. Since the output gear 2 is axially fixed to the motor shaft 2 by a rolling bearing, the distance of the sensor magnet 6a relative to the sensor can be fixed. In this embodiment, the sensor magnet 6a, in combination with the position sensor 6, detects the angular position of the output gear 2 by changes in the magnetic field. Common types of magnets include permanent magnets or electromagnets. In this embodiment, the sensor magnet is a permanent magnet.

[0034] In this utility model, see especially Figure 2 The position sensor 6 and the sensor magnet 6a are arranged with a gap of 3mm to 4.24mm, for example, 3.5mm. If the distance between the magnet and the sensor is greater than 4.24mm, the magnetic field strength decreases, and the sensor cannot detect changes in the magnetic field, causing the gear output shaft position to deviate from the design range (position accuracy < -0.885°). Conversely, if the distance between the magnet and the sensor is less than 3.0mm, the magnetic field strength will be very strong, interfering with the sensor and causing the gear output shaft position to deviate from the design range (position accuracy > +0.885°). Therefore, the magnet and sensor need to be placed within a reasonable distance range (3~4.24mm) to ensure that the sensor can accurately detect changes in the magnetic field, thereby achieving accurate position measurement.

[0035] Position sensors and sensor magnets are widely used in modern industry and consumer electronics, often for detecting the position or motion of objects. They are usually used together, with the sensor magnet being an important component or auxiliary element of the position sensor, providing the required magnetic field signal and offering a stable, responsive magnetic field for the sensor to detect.

[0036] Although the present invention has been disclosed above with reference to preferred embodiments, it is not limited thereto. Any combinations, changes, and modifications made by those skilled in the art without departing from the spirit and scope of the present invention should be included within the protection scope of the present invention. Therefore, the protection scope of the present invention should be determined by the scope defined in the claims.

Claims

1. An actuator having low system friction torque, characterized by, The actuator (100) comprises: a motor shaft (1); an output gear (2) mounted to the motor shaft (1) by a rolling bearing (3); a gear transmission mechanism (2a) for transmitting the rotary motion of the motor shaft (1) to the output gear (2); one end (1a) of the motor shaft for receiving the rolling bearing (3) is provided with a first limiting structure (4), and one side of the output gear (2) facing the rolling bearing is provided with a second limiting structure (5), wherein the rolling bearing is axially fixed on the motor shaft through the cooperation of the first limiting structure and the second limiting structure.

2. The actuator according to claim 1, wherein the rolling bearing (3) comprises a bearing inner ring (31) and a bearing outer ring (32); the first limiting structure (4) comprises a first stepped portion (41) provided on the motor shaft and a circlip (42) spaced apart from the first stepped portion for axially fixing the bearing inner ring (31); and one side of the output gear (2) facing the rolling bearing is provided with a mounting hole (20), wherein the mounting hole is a stepped hole, and the second limiting structure (5) is a second stepped portion of the stepped hole for axially fixing the bearing outer ring (32).

3. The actuator according to claim 2, wherein the stepped hole comprises a first hole section (21) having a first diameter and a second hole section (22) having a second diameter, wherein the first diameter is greater than the second diameter; and the output gear (2) is press-fitted to the bearing outer ring of the rolling bearing through the first hole section (21).

4. The actuator according to claim 3, wherein the one end (1a) of the motor shaft is configured as a non-spherical head end portion, which extends into the second hole section and is in clearance fit with the second hole section.

5. The actuator of claim 3, wherein, The stepped hole further comprises a third hole section (23) between the first hole section (21) and the second hole section (22), wherein the circlip is located in the third hole section.

6. The actuator according to any one of claims 1 to 5, wherein the actuator further comprises a printed circuit board, a position sensor (6) for determining the angular position of the output gear, and a sensor magnet (6a) opposite to the position sensor, wherein the position sensor is fixedly mounted on one side of the printed circuit board (7) facing the output gear, and the sensor magnet (6a) is fixedly mounted to the output gear (2).

7. The actuator of claim 6, wherein, The sensor magnet (6a) is fixedly mounted to the output gear through the cooperation of a stud (61) and an opening (23a) provided in the output gear.

8. The actuator of claim 6, wherein, The gap between the position sensor and the sensor magnet is 3mm to 4.24mm.

9. The actuator of any one of claims 1 to 5, wherein, The rolling bearing (3) is a deep groove ball bearing, a tapered roller bearing, an angular contact bearing, or a cylindrical roller bearing.

10. The actuator of any one of claims 1 to 5, wherein, The gear mechanism (2a) comprises a pinion (2a1) fixedly mounted to the motor shaft (1) and a transmission gear (2a2) engaged with the pinion, which is engaged with the output gear (2).

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