Linear robot joint EMA execution device

Abstract

The invention provides a light, large-stroke and short-installation-length linear robot joint EMA execution device. The device comprises an upper supporting lug, a rear end cover, a coded disc installation base, a coded disc, an actuator shell, a lower supporting lug, a reverse planetary roller lead screw, a frameless torque motor stator, a frameless torque motor rotor assembly and a front end cover. The frameless torque motor rotor assembly is composed of a reverse planetary roller screw nut, a motor balancing ring, motor magnetic steel, a motor rotor protection sleeve, a locking nut, an angular contact ball bearing and a deep groove ball bearing. According to the device, the structural characteristics of the reverse planetary roller lead screw are utilized, the motor-reverse planetary roller lead screw integrated design is adopted, a Halbach structure is adopted for magnetic steel of the permanent magnet synchronous motor, and the high power density, the high volume density and the large stroke and installation zero position length ratio can be achieved.

Description

Technical Field

[0001] The invention belongs to the field of robots, and in particular relates to a linear EMA actuator for robot joints. Background Art

[0002] Robot joints are a type of actuator that drives the robot's trunk to move. They are divided into two categories: electromechanical (EMA) and electrostatic (EHA). The electromechanical (EMA) is further divided into two structural forms of joint modules. One is that the motor drives the harmonic or planetary reducer to output rotational motion as the rotational motion of the joint; the other is that the motor drives the lead screw to output linear motion, and then drives the rocker arm to rotate to drive the joint rotation. The performance of the robot joint directly determines the key indicators of the robot's entire machine, such as the bounce height and movement speed, so high-performance robot joints are one of the key technologies for the development of robot technology.

[0003] CN 106787412A, an integrated design highly integrated electromechanical actuator, applied by Beijing Precision Electromechanical Control Equipment Research Institute, and CN 117578791 A, an integrated linear drive electric cylinder integrating drive, perception and control, applied by Harbin Institute of Technology, can both be used for linear robot joint EMA actuators, but these devices have the following problems: the rotors of the motor angle measurement sensors are all installed axially, which increases the axial size. For example, the invention patent CN106787412A, an integrated design highly integrated electromechanical actuator, has a smaller inner diameter of the angular contact ball bearing for the lead screw, which also occupies the axial size of the actuator, and has a longer installation length under the same stroke conditions. For example, the invention patent CN117578791 A, an integrated linear drive electric cylinder integrating drive, perception and control, has an additional guide mechanism to prevent the lead screw nut and the lead screw from rotating, which increases the volume and complexity of the actuator. For example, invention patent CN117578791 A discloses an integrated linear drive electric cylinder screw that integrates drive, sensing and control. The angular contact ball bearing is arranged on one side of the extended end of the screw, making the motor housing a load-bearing component. The housing thickness needs to be increased to ensure the load-bearing performance.

[0004] For example, in the invention patent CN117578791 A, an integrated linear drive electric cylinder integrating drive, sensing and control, after the screw shaft is extended, the threads on the screw shaft are directly exposed to the external environment. After being contaminated by dust, the screw is very likely to get stuck. Summary of the invention

[0005] The purpose of the present invention is to overcome the above-mentioned deficiencies of the prior art and to provide a lightweight, long-stroke, short-installation-length linear robot joint EMA actuator to achieve the purposes of high power density, high volume density and a large stroke to installation zero length ratio.

[0006] The present invention provides a light-weight, long-stroke, short-installation-length linear robot joint EMA actuator, which comprises an upper support ear, a rear end cover, a code disc mounting seat, a code disc, an actuator housing, a lower support ear, a reverse planetary roller screw, a frameless torque motor stator, a frameless torque motor rotor assembly, and a front end cover.

[0007] Furthermore, the stator of the frameless torque motor is heat-fitted inside the actuator housing and axially positioned by a stepped shaft shoulder.

[0008] Furthermore, the outer ring of the deep groove ball bearing of the frameless torque motor rotor assembly is installed in the bearing hole of the front end cover, and the angular contact ball bearing is installed in the bearing hole of the actuator housing.

[0009] Furthermore, the long screw passes through the rear cover and the code disc mounting seat and is tightened on the threaded hole of the actuator housing; the rear cover is connected to the upper support ear by thread. The rear cover integrates the function of the tension and pressure sensor, and the sensor outputs an electrical signal to reflect the tension and pressure load borne by the linear robot joint EMA actuator.

[0010] Furthermore, the frameless torque motor rotor assembly is composed of a reverse planetary roller screw nut, a motor balance ring, a motor magnet, a motor rotor protective cover, a locking nut, an angular contact ball bearing, and a deep groove ball bearing. The frameless torque motor rotor assembly is integrated with the reverse planetary roller screw nut in an integrated design. During assembly, the motor balance ring a and the motor balance ring b are successively hot-fitted onto the reverse planetary roller screw nut, wherein the inner aperture of the motor balance ring a is larger than that of the motor balance ring b, thereby improving the installation processability. Then, the motor magnet is bonded to the outside of the reverse planetary roller screw nut, the motor rotor protective cover is hot-fitted onto the outside of the balance ring and the magnet, the angular contact ball bearing and the angular contact ball bearing are installed at one end of the reverse planetary roller screw nut and tightened with a locking nut, and the deep groove ball bearing is hot-fitted onto the other end of the reverse planetary roller screw nut and positioned by a shoulder step.

[0011] Furthermore, the magnets are divided into radially magnetized magnets and tangentially magnetized magnets, which are arranged in a Halbach array and installed on the outer polygonal plane of the reverse planetary roller screw nut, and a motor rotor protection cover is installed on the outer layer to prevent the magnets from falling out during high-speed rotation.

[0012] Furthermore, the inner thread hole of the lower support ear and the outer connection thread of the reverse planetary roller screw are keyed to prevent loosening. When in use, first screw the lower support ear in to a suitable length, align the inner thread keyway with the outer thread keyway, push the flat key in, and finally install the top screw 1 to prevent the flat key from slipping out. When the flat key needs to be removed, first screw out the top screw 1 and then push the flat key out through the front key hole.

[0013] Furthermore, the actuator locks the extension and retraction amount of the reverse planetary roller screw at zero position through a zero position tool before installation. One end of the zero position tool is installed on the front end cover by a screw, and the other end locks the position through an arc-shaped protrusion that cooperates with the arc-shaped groove on the reverse planetary roller screw.

[0014] Furthermore, the code disc stator is mounted on the code disc mounting seat, the code disc rotor is axially positioned by the stepped shoulder of the reverse planetary roller screw nut, and is radially mounted and tightened by the top screw 2. The inner diameter of the code disc rotor is larger than the outer diameter of the safe wall thickness allowed by the reverse planetary roller screw nut.

[0015] Furthermore, a slot structure is provided on one side of the reverse planetary roller screw nut close to the stepped shoulder of the encoder rotor installation, so as to facilitate rotation and debugging during installation.

[0016] The undisclosed technologies in the present invention are common knowledge to those skilled in the art.

[0017] The beneficial effects of the present invention are as follows:

[0018] 1. The present invention utilizes the structural characteristics of the reverse planetary roller screw and adopts the integrated design of "motor-reverse planetary roller screw". Compared with the ball screw, it saves the protective extended thread structure and has a shorter total length. At the same time, the screw nut is integrated with the motor, which significantly improves the system power density;

[0019] 2. The present invention utilizes the small lead characteristic of the planetary roller screw, eliminates the reducer, and reduces the weight;

[0020] 3. The permanent magnet synchronous motor magnetic steel of the present invention adopts Halbach structure, which avoids the disadvantage of non-magnetic conductivity of the planetary roller screw material and improves the power density of the motor;

[0021] 4. The screw support bearing of the present invention is installed on one side of the code disc, so that the force transmission path does not pass through the motor housing, so that the motor housing can be thinner and lighter;

[0022] 5. The present invention uses a magnetic code disk that can be radially mounted on the screw shaft, which releases the working stroke and shortens the installation length;

[0023] 6. The anti-rotation of the lower support ear of the present invention adopts a key connection form, eliminating the traditional locking nut and releasing the working stroke;

[0024] 7. The actuator of the present invention realizes the guiding function by designing arc-shaped bosses on the upper and lower ears, thereby simplifying the structural design and providing an additional degree of freedom of rotation around the output shaft when used for a multi-degree-of-freedom joint with double push rods. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] The accompanying drawings constituting a part of the present application are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention:

[0026] Figure 1 It is a schematic diagram of the mechanism in an embodiment of the present invention;

[0027] Figure 2 is a schematic diagram of a rotor assembly according to an embodiment of the present invention;

[0028] Figure 3 is a schematic diagram of a Halbach array of a motor according to an embodiment of the present invention;

[0029] Figure 4 The bolt head anti-rotation structure according to an embodiment of the present invention;

[0030] Figure 5 It is a zeroing tool according to an embodiment of the present invention;

[0031] Figure 6 This is a code disk installation structure according to an embodiment of the present invention;

[0032] Figure 7 This is a straight groove structure at the tail end of a lead screw in an embodiment of the present invention.

[0033] Among them: 1-upper ear 2-rear cover 3-code disc mounting seat 4-code disc 5-actuator housing 6-lower ear 7-reverse planetary roller screw 8-frameless torque motor stator 9-frameless torque motor rotor assembly 10-front cover 11-motor balance ring 12-motor magnet 13-motor rotor protection cover 14-locking nut 15-angular contact ball bearing 16-deep groove ball bearing 17-top screw 1 18-flat key 19-zero position tooling 20-screw 22-top screw 2 23-long screw 4a-code disc stator 4b-code disc rotor 6a-internal thread keyway 6b-front end back key hole 7a-reverse planetary roller screw nut 7b-reverse planetary roller screw lead 7c-external thread keyway 7d-arc-shaped groove 7e-stepped shoulder 7f-slot structure 11a-motor balance ring a 11b-motor balance ring b12a-radial magnetized magnetic steel 12b-tangential magnetized magnetic steel 15a-angular contact ball bearing a 15b-angular contact ball bearing b19a-arc-shaped protrusion DETAILED DESCRIPTION

[0034] In order to enable those skilled in the art to better understand the scheme of the present invention, the technical scheme in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work should fall within the scope of protection of the present invention.

[0035] The embodiment of the present invention provides a linear robot joint EMA actuator. Figure 1 As shown, the linear robot joint EMA actuator of the present invention comprises an upper support ear (1), a rear end cover (2), a code disc mounting seat (3), a code disc (4), an actuator housing (5), a lower support ear (6), a reverse planetary roller screw (7), a frameless torque motor stator (8), a frameless torque motor rotor assembly (9), and a front end cover (10).

[0036] Furthermore, the lead of the reverse planetary roller screw is less than 2 mm.

[0037] like Figure 1 As shown, the motor stator (8) is heat-fitted inside the actuator housing (5) and axially positioned by a stepped shaft shoulder.

[0038] like Figure 1 As shown, the outer ring of the deep groove ball bearing (16) of the frameless torque motor rotor assembly (9) is installed in the bearing hole of the front cover (10), and the angular contact ball bearing (15) is installed in the bearing hole of the actuator housing (5).

[0039] like Figure 1 As shown, the long screw (23) passes through the rear cover (2) and the code disc mounting seat (3) and is tightened on the threaded hole of the actuator housing (5); the rear cover (2) is connected to the upper support ear (1) by threading. The rear cover integrates the function of the tension and pressure sensor, and the sensor outputs an electrical signal to reflect the tension and pressure load borne by the linear robot joint EMA actuator.

[0040] like Figure 2 As shown, the frameless torque motor rotor assembly (9) is composed of a reverse planetary roller screw nut (7a), a motor balance ring (11), a motor magnet (12), a motor rotor protection sleeve (13), a locking nut (14), an angular contact ball bearing (15), and a deep groove ball bearing (16). The frameless torque motor rotor assembly (9) is integrated with the reverse planetary roller screw nut (7a) in an integrated design. During assembly, the motor balance ring a (11a) and the motor balance ring b (11b) are heat-fitted onto the reverse planetary roller screw nut in sequence. The inner diameter of the motor balance ring a (11a) is larger than that of the motor balance ring b (11b), thereby improving the installation processability. Then, the motor magnet (12) is bonded to the outside of the reverse planetary roller screw nut (7a), the motor rotor protection cover (13) is heat-fitted to the outside of the motor balance ring (11) and the motor magnet (12), the angular contact ball bearing a (15a) and the angular contact ball bearing b (15b) are installed on one end of the reverse planetary roller screw nut (7a) and tightened with a locking nut (14), and the deep groove ball bearing (16) is heat-fitted to the other end of the reverse planetary roller screw nut (7a) and positioned by the shaft shoulder step;

[0041] like Figure 3 As shown, the motor magnets are divided into radial magnetized magnets (12a) and tangential magnetized magnets (12b), which are arranged in a Halbach array and installed on the outer polygonal plane of the reverse planetary roller screw nut (7a), and a motor rotor protection cover (13) is installed on the outer layer to prevent the magnets from falling out under high-speed rotation.

[0042] like Figure 4 As shown, the internal thread hole of the lower support ear (6) and the external connection thread of the reverse planetary roller screw (7b) are keyed to prevent loosening. When in use, first screw the lower support ear (6) to a suitable length, align the internal thread keyway (6a) and the external thread keyway (7c), push the flat key (18), and finally install the top screw 1 (17) to prevent the flat key from sliding out. When the flat key (18) needs to be removed, first screw out the top screw 1 (17) and then push the flat key out through the front end key hole (6b).

[0043] like Figure 5 As shown, the actuator locks the extension and contraction amount of the reverse planetary roller screw (7b) at zero position through a zero position fixture (19) before installation. One end of the zero position fixture (19) is installed on the front end cover (10) through a screw (20), and the other end cooperates with the arc-shaped groove (7d) on the reverse planetary roller screw (7b) through an arc-shaped protrusion (19a) to lock the position.

[0044] like Figure 6 As shown, the code disc stator (4a) is mounted on the code disc mounting seat (3), the code disc rotor (4b) is axially positioned by the stepped shaft shoulder (7e) of the reverse planetary roller screw nut (7a), and is radially installed with a top screw 2 (22) to tighten. The inner diameter of the code disc rotor is larger than the outer diameter of the safe wall thickness allowed by the reverse planetary roller screw nut (7a).

[0045] like Figure 7 As shown, a slot structure (7f) is provided on one side of the reverse planetary roller screw nut (7a) close to the step shoulder (7e) of the encoder rotor (4b) for installation, so as to facilitate rotation and debugging during installation.

[0046] The undisclosed technologies in the present invention are common knowledge to those skilled in the art.

[0047] The above description of the disclosed embodiments enables one skilled in the art to implement or use the present invention. Various modifications to these embodiments will be apparent to one skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the scope of the present invention. Therefore, the present invention will not be limited to the embodiments shown herein, but rather to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A linear robot joint EMA actuator, characterized in that: include: Upper support ear, rear end cover, code disc mounting seat, code disc, actuator housing, lower support ear, reverse planetary roller screw, frameless torque motor stator, frameless torque motor rotor assembly, front end cover, wherein the rear end cover is integrated with a tension and pressure sensor, and the sensor outputs an electrical signal to respond to the tension and pressure loads borne by the linear robot joint EMA actuator.

2. A linear robot joint EMA actuator according to claim 1, characterized in that: The frameless torque motor rotor assembly consists of a reverse planetary roller screw nut, a motor balance ring a, a motor balance ring b, a motor magnetic steel, a motor rotor protection sleeve, a locking nut, an angular contact ball bearing, and a deep groove ball bearing.

3. A linear robot joint EMA actuator according to claim 2, characterized in that: The outer ring of the deep groove ball bearing of the frameless torque motor rotor assembly is installed in the bearing hole of the front end cover, and the angular contact ball bearing is installed in the bearing hole of the actuator housing.

4. A linear robot joint EMA actuator according to claim 2, characterized in that: The angular contact ball bearing comprises an angular contact ball bearing a and an angular contact ball bearing b. When the frameless torque motor rotor assembly is assembled, the motor balance ring a and the motor balance ring b are successively heat-fitted onto the reverse planetary roller screw nut, and then the motor magnet is bonded to the outside of the reverse planetary roller screw nut, the motor rotor protection cover is heat-fitted onto the motor balance rings a, b and the outside of the motor magnet, the angular contact ball bearing a and the angular contact ball bearing b are installed on one end of the reverse planetary roller screw nut and tightened with a locking nut, the deep groove ball bearing is heat-fitted onto the other end of the reverse planetary roller screw nut and positioned by a shaft shoulder step, wherein the inner aperture of the motor balance ring a is larger than that of the motor balance ring b.

5. The linear robot joint EMA actuator according to claim 2, characterized in that: The motor magnets are divided into radial magnetized magnets and tangential magnetized magnets, which are arranged in a Halbach array and installed on the outer polygonal plane of the reverse planetary roller screw nut, and a motor rotor protection cover is installed on the outer layer to prevent the magnets from falling out during high-speed rotation.

6. A linear robot joint EMA actuator according to claim 1, characterized in that: The internal threaded hole of the lower support ear and the external connecting thread of the reverse planetary roller screw are keyed to prevent loosening. When in use, first screw the lower support ear in to a suitable length, align the internal thread keyway and the external thread keyway and push the flat key in, and finally install the top screw 1 to prevent the flat key from slipping out. When the flat key needs to be removed, first screw out the top screw 1 and then push the flat key out through the front key withdrawal hole.

7. The linear robot joint EMA actuator according to claim 5, characterized in that: The extension and retraction amount of the reverse planetary roller screw is locked at the zero position by means of a zero position fixture. One end of the zero position fixture is mounted on the front end cover by means of a screw, and the other end locks the position by means of an arc-shaped protrusion that cooperates with an arc-shaped groove on the reverse planetary roller screw.

8. The linear robot joint EMA actuator according to claim 2, characterized in that: A code disc stator is installed on the code disc mounting seat, the code disc rotor is axially positioned by a stepped shoulder of a reverse planetary roller screw nut, and is radially installed with a top screw 2 for tightening, and the inner hole diameter of the code disc rotor is larger than the outer diameter of the safe wall thickness allowed by the reverse planetary roller screw nut.

9. The linear robot joint EMA actuator according to claim 2, characterized in that: The reverse planetary roller screw nut has a slot structure on one side close to the mounting step shoulder of the encoder rotor, which is convenient for rotation and debugging during installation.

10. A linear robot joint EMA actuator according to any one of claims 1 to 9, characterized in that: The reverse planetary roller screw has a lead of less than 2 mm.

Images