Brake unit, joint drive device and robot

Abstract

a brake unit including a motor rotor, a brake disc fixed to the motor rotor, a friction plate fixed so as to surround the brake disc, a bearing rotatably fitted into the motor rotor, an electromagnet assembly fixed to the bearing, a baffle fixed to the electromagnet assembly and positioned on one side of the friction plate, an armature slidably fitted into the motor rotor and positioned on the other side of the friction plate, and positioned between the brake disc and the electromagnet assembly, and a spring assembly provided between the armature and the electromagnet assembly, wherein when the electromagnet assembly is de-energized, the armature is pressed by the spring assembly to move in a direction approaching the baffle, and the friction plate is sandwiched between the armature and the baffle, thereby achieving braking.

Description

[Technical field]

[0001] The present application relates to the technical field of brakes, and in particular to a brake unit, an articulated drive device and a robot. CROSS-REFERENCE TO RELATED APPLICATIONS This application claims priority to a Chinese patent application filed with the State Intellectual Property Office of China on December 21, 2021, bearing application number 2021115710751 and entitled "Brake Unit, Articulated Drive Device and Robot", the entire contents of which are incorporated herein by reference. [Background technology]

[0002] An industrial robot is an automatically controlled, reprogrammable, versatile manipulator with multiple degrees of freedom and the ability to perform work tasks independently. The industrial robot may have several axes, each of which is powered by an actuator, e.g. an electric motor. The operation of each motor is stopped by a brake, which brakes the operation of the motor.

[0003] A conventional brake mechanism includes a friction member for fixedly connecting to a motor rotor, a brake member abutting one side of the friction member, a thrust member abutting the other side of the friction member for providing a thrust to the brake member such that the thrust on the brake member is adjustable, and a lock mechanism for preventing the brake member from rotating based on a brake command. The lock mechanism includes a striker and a drive member connected to each other, an outer ring of the brake member is provided with brake teeth, and the drive member is used to drive the striker to extend and retract, so that the striker can extend in response to the brake command and contact the brake teeth to prevent the brake member from rotating.

[0004] Although such multi-disc brakes are capable of achieving braking, they have some obvious drawbacks.

[0005] (1) The axial dimension is large, and the weight distribution in the circumferential direction is uneven. Since the electromagnetic switch is mounted in the axial direction, the axial dimension of the entire joint becomes large, which further affects the structural form and mounting of other members; the axial space inside the joint is very limited, and the axial structure is not compact enough.

[0006] (2) Low reliability and durability of brake collisions. As the number of collisions increases, many small pits and debris are generated at the collision site between the striker and the brake teeth, causing wear and reducing reliability and durability. Summary of the Invention [Problem to be solved by the invention]

[0007] According to some embodiments, a brake unit, an articulation drive and a robot are provided. [Means for solving the problem]

[0008] a brake unit including a motor rotor, a brake disc fixed to the motor rotor, a friction plate fixed so as to surround the brake disc, a bearing rotatably fitted into the motor rotor, an electromagnet assembly fixed to the bearing, a baffle fixed to the electromagnet assembly and positioned on one side of the friction plate, an armature slidably fitted into the motor rotor and positioned on the other side of the friction plate, and positioned between the brake disc and the electromagnet assembly, and a spring assembly provided between the armature and the electromagnet assembly, wherein when the electromagnet assembly is de-energized, the armature is pressed by the spring assembly to move in a direction approaching the baffle, and the friction plate is sandwiched between the armature and the baffle, thereby achieving braking.

[0009] The joint drive device includes a motor and the above brake unit.

[0010] A robot including the above-mentioned joint drive device.

[0011] The details of one or more embodiments of the invention are set forth in the accompanying drawings and the description below. Other features, objects, and advantages of the invention will become apparent from the description, the accompanying drawings, and the claims. [Brief description of the drawings]

[0012] The above and other objects, features and advantages of the present application will become more apparent from a more particular description of the preferred embodiments of the present application, as illustrated in the accompanying drawings, in which like reference numerals refer to like parts throughout and the drawings are not drawn to scale with respect to actual dimensions, with emphasis on illustrating the subject matter of the present application. [Figure 1] FIG. 1 is a perspective view of a brake unit according to an embodiment. [Diagram 2] FIG. 2 is a front view of the brake unit shown in FIG. [Diagram 3] FIG. 2 is an exploded perspective view of the brake unit shown in FIG. [Figure 4] FIG. 3 is a cross-sectional view taken along line AA in FIG. 2. [Diagram 5] FIG. 2 is a schematic diagram of a friction plate and a brake disc combined. [Figure 6] FIG. 2 is a block diagram of a joint driving device according to an embodiment. [Figure 7] FIG. 1 is a schematic diagram of a robot according to an embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0013] In order to make the objectives, technical solutions and advantages of the present application clearer, the present application will be described in more detail below with reference to the drawings and specific embodiments. It should be understood that the specific embodiments described herein are only for interpreting the present application, and do not limit the protection scope of the present application.

[0014] It should be noted that when an element is referred to as "fixed" to another element, it may be directly on the other element or there may be intervening elements. When an element is referred to as "connected" to another element, it may be directly connected to the other element or there may be intervening elements. When an element is referred to as "abutting" another element, it may be directly abutting the other element or there may be intervening elements. Terms such as "vertical," "horizontal," "left," "right," and the like, as used herein, are for illustrative purposes only and do not refer to exclusive embodiments.

[0015] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art to which this application belongs. The terms used herein are only for the purpose of describing specific embodiments and are not intended to limit the present application. The term "and / or" used herein includes any and all combinations of one or more of the associated listed items.

[0016] 1 to 3, according to one embodiment of the present application, there is provided a brake unit 100 for use in a robot, the brake unit 100 including a motor rotor 10, a brake disc 20, a friction plate 30, a bearing 40, an electromagnet assembly 50, a baffle 60, an armature 70 and a spring assembly 80. The brake disc 20 and the friction plate 30 are fitted and fixed to the motor rotor 10. The bearing 40 is movably fitted to the motor rotor 10, and the electromagnet assembly 50, the baffle 60 and the armature 70 are fixed to the bearing 40.

[0017] As shown in FIG. 3, the motor rotor 10 is a cylindrical shaft extending from the motor 222 (see FIG. 7). The motor rotor 10 is provided with a number of keyways 12 extending in the axial direction. In this embodiment, the four keyways 12 are equally spaced and distributed on the circumferential surface of the motor rotor 10. The brake disc 20 is generally ring-shaped, and is provided with a number of positioning grooves 22 corresponding to the number of keyways 12 on its inner edge. The brake unit 100 further includes a number of fixed keys 18. The fixed keys 18 are simultaneously inserted into the keyways 12 and the positioning grooves 22, so that the brake disc 20 is fixed to the motor rotor 10 by the fixed keys 18, thereby causing the brake disc 20 to rotate together with the motor rotor 10. In this embodiment, the fixed keys 18 are hook keys, which can realize accurate positioning in three directions: radial, circumferential and axial. In addition, the fixed key 18 is tightly fitted with the motor rotor 10, and during installation, the fixed key 18 is coated with a first adhesive layer on both sides and then pressed into the keyway 12 to improve the stability and reliability of the structure. Specifically, the first adhesive may be LOCTITE 609 adhesive.

[0018] 3 and 4, the motor rotor 10 is further provided with a ring-shaped first positioning boss 14. The brake unit 100 further includes a washer 90. The washer 90 is located between the first positioning boss 14 and the brake disc 20, and adjusts the axial position of the brake disc 20 on the motor rotor 10. Since the outer diameter of the first positioning boss 14 is larger than the inner diameter of the brake disc 20, the brake disc 20 can abut against the first positioning boss 14 via the washer 90, thereby realizing the axial positioning of the brake disc 20 on the motor rotor 10.

[0019] 3 and 5, the generally ring-shaped brake disc 20 can be made of a metal material. The friction plate 30 is generally ring-shaped, fixed to surround the periphery of the brake disc 20, and flush with the brake disc 20. The friction plate 30 can be made of a non-metallic material, such as ceramic or rubber, or engineering plastics with other suitable friction coefficients. The outer edge of the brake disc 20 extends radially to form a blade 24, and an accommodation groove 32 is opened on the inner edge of the friction plate 30 to accommodate the blade 24. In this embodiment, the blade 24 is generally U-shaped and includes two fork arms 242, 244 that are parallel and spaced apart from each other. The two fork arms 242, 244 contact two opposing side walls of the accommodation groove 32, respectively. In this embodiment, the number of the blades 24 is six, and the six blades 24 are equally and symmetrically distributed at intervals of 60° on the outer edge of the brake disc 20. The number and positions of the accommodation grooves 32 correspond one-to-one to the number and positions of the blades 24.

[0020] When the motor rotor 10 accelerates from a stationary state and starts to rotate counterclockwise, the brake disc 20 accelerates and starts to rotate together with the motor rotor 10, and at this time, the fork arm 242 generates a pressure F1 against one side wall of the accommodation groove 32, driving the friction plate 30 to rotate together. When the friction plate 30 is sandwiched between the armature 70 and the baffle 60 to realize braking, the side wall of the accommodation groove 32 generates a pressure F1' against the fork arm 242. Since the fork arm 242 has a long and thin rod structure and the brake disc 20 is manufactured from a material with excellent flexibility, when the friction plate 30 is sandwiched between the armature 70 and the baffle 60 and stops rotating, the six fork arms 242 all receive resistance F1' from the six accommodation grooves 32 (F1' received by each fork arm 242 is different), and generate bending deformation (deflection) of different degrees. Thereafter, the fork arm 242 returns to its original shape due to the action of its own elasticity, and the motor rotor 10 stops rotating. Similarly, when the motor rotor 10 accelerates from a stationary state and rotates clockwise, the brake disc 20 accelerates and starts to rotate together with the motor rotor 10, and at this time, the fork arm 244 generates a pressure F2 against the other side wall of the accommodation groove 32, driving the friction plate 30 to rotate together. When the friction plate 30 is sandwiched between the armature 70 and the baffle 60 to realize braking, the side wall of the accommodation groove 32 generates a pressure F2' against the fork arm 244. Since the fork arms 244 have a long and thin rod structure and the brake disc 20 is made of a material with excellent flexibility, when the friction plate 30 is clamped between the armature 70 and the baffle 60 and stops rotating, the six fork arms 244 all receive resistance F2' from the six accommodation grooves 32 (F2' received by each fork arm 244 is different), generating bending deformation (deflection) to different degrees. After that, the fork arms 244 return to their original shape by the action of their own elasticity, and the motor rotor 10 stops rotating. Therefore, the fork arms 244 are slightly bent and deflected.Therefore, during starting and braking, the U-shaped fork arms 242, 244 of the brake disc 20 can absorb the impact energy caused by the collision by elastic deformation, and also protect other components in the joint, such as the reducer. Also, compared with the conventional single blade solution, any one of the six fork arms 244, 242 always receives only one-sided force, thereby avoiding the defect that the conventional single blade is prone to fatigue failure and breakage due to repeated large impact forces from two directions, and improving the durability and reliability of the use of the brake disc 20.

[0021] 3 and 4, the bearing 40 is fitted to the end of the motor rotor 10. The inner ring of the bearing 40 is tightly fitted and fixed to the motor rotor 10, and the outer ring of the bearing 40 can rotate freely relative to the inner ring. In this embodiment, the bearing 40 is a deep groove ball bearing, which is characterized by its low friction resistance and high rotation speed, and can be used in mechanisms that receive radial loads or combined loads that act simultaneously in the radial and axial directions. The motor rotor 10 is further provided with a ring-shaped second positioning boss 16. Since the outer diameter of the second positioning boss 16 is larger than the inner diameter of the inner ring of the bearing 40, one side of the bearing 40 can abut against the second positioning boss 16, thereby realizing the axial positioning of the bearing 40 on the motor rotor 10.

[0022] The electromagnet assembly 50 is fixedly installed on the bearing 40. As shown in FIG. 3, the electromagnet assembly 50 includes a case 52 and an electromagnet 54 housed in the case 52. The case 52 is generally ring-shaped, and a ring-shaped housing cavity 522 is opened on one side thereof. The ring-shaped electromagnet 54 is fixedly housed in the housing cavity 522 and faces the armature 70. The depth of the housing cavity 522 is smaller than the thickness of the case 52, thereby dividing the case 52 into an inner ring 524 and an outer ring 526. The inner ring 524 and the outer ring 526 have edges that are flush with each other and are connected (see FIG. 4). The inner ring 524 is fixedly fitted into the outer ring of the bearing 40 and is press-fitted with the outer ring. In this embodiment, the outer ring of the bearing 40 is further coated with a second adhesive layer, thereby improving the connection strength between the bearing 40 and the electromagnet assembly 50. The second adhesive may be a Rakuten 609 adhesive. The spring assembly 80 is provided in the outer ring 526. Specifically, a plurality of receiving holes 528 are opened in the outer ring 526, and the plurality of spring assemblies 80 are respectively received in the plurality of receiving holes 528. Each receiving hole 528 penetrates both sides of the outer ring 526. The receiving hole 528 further includes a spring receiving portion 5282 and a threaded portion 5284. The spring receiving portion 5282 faces the armature 70, and the threaded portion 5284 is connected to the spring receiving portion 5282 so as to be located on one side of the outer ring 526 away from the armature 70. The diameter of the spring receiving portion 5282 is slightly larger than the diameter of the threaded portion 5284.

[0023] The spring assembly 80 includes a spring 82, an adjustment screw 84, and a gasket 86. One end of the spring 82 is accommodated in a spring accommodating portion 5282 of the accommodation hole 528, and the other end of the spring 82 protrudes from the spring accommodating portion 5282. Alternatively, the spring 82 may be abutted against one side of the armature 70. The adjustment screw 84 is screwed into a threaded portion 5284 of the accommodation hole 528, and can be moved axially by rotating the threaded portion 5284. The gasket 86 is located between the spring 82 and the adjustment screw 84. Therefore, the position of the adjustment screw 84 in the threaded portion 5284 can be adjusted by an L-shaped wrench, and the initial compression amount of the spring 82 (the greater the compression deformation of the spring, the greater the elasticity) can be precisely adjusted, and further, the frictional force of the armature 70 against the friction plate 30 can be adjusted by adjusting the degree of elastic abutment of the spring 82 against the armature 70. Needless to say, the gasket 86 may be omitted, in which case the adjustment screw 84 directly abuts the end of the spring 82. In this embodiment, the number of the spring assemblies 80 is six, and the six spring assemblies 80 are equally and symmetrically distributed on the outer ring 526 at intervals of 60°.

[0024] The armature 70 is generally ring-shaped, fitted to the motor rotor 10, and can slide left and right in the axial direction of the motor rotor 10. The armature 70 is located on one side of the brake disc 20 and the friction plate 30, and the baffle 60 is located on the other side of the brake disc 20 and the friction plate 30. The baffle 60 is generally ring-shaped, fitted to the motor rotor 10, and fixed to the electromagnet assembly 50. Specifically, as shown in FIG. 3, the baffle 60 is provided with a stopper protrusion 62 extending in the axial direction, the armature 70 is provided with a notch 72 corresponding to the stopper protrusion 62, and the baffle 60 is fixed to the outer ring 526 of the electromagnet assembly 50 by a screw 64 extending through the stopper protrusion 62. Thus, the baffle 60 and the electromagnet assembly 50 are fixed to one another and do not rotate with the motor rotor 10 , and the armature 70 can slide in the axial direction of the motor rotor 10 between the baffle 60 and the electromagnet assembly 50 .

[0025] The operating principle of the brake unit 100 will be briefly explained below. When the joint operates normally and braking is not required, the electromagnet assembly 50 is normally energized, the electromagnet 54 generates magnetism and attracts the armature 70, and at this time, the armature 70 moves in a direction away from the baffle 60 against the elastic force of the spring 82 and separates from the friction plate 30. At this time, the gap between the baffle 60 and the armature 70 is larger than the thickness of the friction plate 30, and there is no friction force between the baffle 60 and the friction plate 30, or the friction force is much smaller than the braking force available for braking, and at this time, the brake disc 20 is in a brake release state, and the motor rotor 10 is rotatable, thereby driving the brake disc 20 to rotate normally together with the friction plate 30.

[0026] When braking of the joint is required, the electromagnet assembly 50 is de-energized, the magnetism from the electromagnet 54 disappears, the armature 70 moves toward the baffle 60 by the elastic force of the spring 82, the armature 70 and the baffle 60 further clamp the friction plate 30 from both sides, and transmit the friction torque acting on the friction plate 30 to the brake disc 20 through the slightly elastically deformable blade 24, and finally the motor rotor 10 is stopped from rotating by the friction torque through the fixed key 18, thereby realizing braking. As can be understood, the current flowing through the electromagnet assembly 50 can be gradually decreased, so that the elastic force of the spring 82 against the armature 70 gradually increases, i.e., the clamping force of the armature 70 against the friction plate 30 gradually increases, thereby achieving a fine and precise braking effect.

[0027] As described above, the brake unit 100 according to this embodiment has the following advantages.

[0028] (1) The brake friction force is adjustable. A plurality of spring assemblies 80 are distributed at equal intervals on the outer ring 526 of the electromagnet assembly 50, and the elastic force of the springs 82 can be adjusted and calibrated by the adjustment screw 84, and the magnitude of the friction force can be further adjusted.

[0029] (2) A new type of friction structure. In the conventional structure, there are two friction plates between two movable armatures, and a friction wheel exists between the two friction plates. The disadvantages of this structure are that there are many parts, the magnetic force required for brake control is large, and the brake pieces are easily worn. The core of the idea of ​​the present application is that the baffle 60 is fixed and the armature 70 is movable, and there are the brake disc 20 and the friction plate 30 between them, and the U-shaped fork arm of the brake disc 20 and the receiving groove 32 of the friction plate 30 are convex and concave fitted. When operating, the brake disc 20 drives the friction plate 30 to rotate together, and when braking, the baffle 60 and the armature 70 clamp the non-metallic friction plate 30, and the friction plate 30 stops rotating after stopping the brake disc 20, so that the brake disc 20 only generates a restorable bending deformation, the brake disc 20 does not wear, there are few parts, the required electromagnetic force is small, the control is simple, and the braking accuracy is high.

[0030] (3) A new fastening method is achieved. The brake disc 20 and the motor rotor 10 are fastened to the fixing key 18 by means of 609 adhesive, which is convenient to assemble and ensures reliable fastening.

[0031] (4) Higher system robustness and functional reliability. Compared with the prior art, the contact surface between the baffle 60 and armature 70 of the present invention and the friction plate 30 is larger, and the friction torque generated by the friction plate 30 being in close contact with the circumference at equal intervals is more stable, which avoids the fatigue failure and breakage caused by the collision between the striker and the brake teeth in the prior art and improves the durability of the operation.

[0032] (5) The layout of the brake unit 100 according to the present embodiment is more compact, which can significantly save the axial space inside the joint. The diameter of the brake unit 100 can be within 60 mm, the thickness can be within 20 mm, and the total weight is lighter.

[0033] (6) All of the members according to the present invention are symmetrically distributed at equal intervals in the circumferential direction, providing excellent dynamic balance.

[0034] (7) The structure of the present invention is simple, and modular design and production are possible. The structure can be widely used in a wide range of rotating body braking applications, and multiple brake structures can be used in series in one system.

[0035] 6 is a block diagram showing a connection configuration on a system of a joint driving device 200 used in a robot according to an embodiment. The joint driving device 200 mainly includes a driving circuit 210 for realizing accurate control of an output shaft of a motor, a photoelectric pulse encoder 220 for performing speed measurement for an output end of a joint, a servo motor 230 with a Hall sensor for providing an output of a driving force, and a harmonic reducer 240 for reducing the rotation speed and improving the driving torque. The joint driving device 200 further includes a brake unit 100 located between the servo motor 230 and the encoder 220. The servo motor 230 includes a motor rotor 10.

[0036] 7 shows an industrial robot 300 having multiple degrees of freedom (DOF). The robot has six axes, and each joint of the axes is driven by an actuator. The robot includes multiple robot arms 320 and multiple joints 340, and the multiple robot arms 320 are connected in sequence, adjacent robot arms 320 are connected by joints, and the above-mentioned joint drive device 200 is provided at the joints.

[0037] The technical features of the above embodiments can be combined in any manner. For the sake of brevity, not all possible combinations of the technical features of the above embodiments are described. However, as long as no contradiction occurs in the combination of these technical features, they should be considered to be within the scope of the present specification.

[0038] The above examples merely show some embodiments of the present application, and the description is made more specific and detailed, and therefore should not be understood as limiting the scope of the claims. It should be noted that those skilled in the art can make some modifications and improvements without departing from the concept of the present application, all of which are included in the protection scope of the present application. Therefore, the protection scope of this patent application should be determined by the attached claims.

Claims

1. A brake unit, A motor rotor; a brake disc fixed to the motor rotor; a friction plate fixed to surround the periphery of the brake disc; a bearing rotatably fitted to the motor rotor; an electromagnet assembly fixedly mounted to the bearing; a baffle fixed to the electromagnet assembly and positioned on one side of the friction plate; an armature slidably fitted to the motor rotor and positioned on the other side of the friction plate and between the brake disc and the electromagnet assembly; a spring assembly disposed between the armature and the electromagnet assembly; when the electromagnet assembly is de-energized, the armature is pushed by the spring assembly to move in a direction approaching the baffle, and the friction plate is sandwiched between the armature and the baffle, thereby achieving braking.

2. The motor rotor is provided with a key groove; A positioning groove is provided on the inner edge of the brake disc, The brake unit further includes a fixed key.

2. The brake unit according to claim 1, wherein the brake disc is fixed to the motor rotor by a fixing key that is simultaneously inserted into the key groove and the positioning groove.

3. 3. The brake unit according to claim 2, wherein a surface of the fixed key is coated with a first adhesive layer.

4. 2. The brake unit according to claim 1, characterized in that the motor rotor is provided with a ring-shaped first positioning boss, and the brake unit further includes a washer, the washer being located between the first positioning boss and the brake disc.

5. 2. The brake unit according to claim 1, wherein an outer edge of the brake disc extends radially to form a blade, and an inner edge of the friction plate forms a receiving groove for receiving the blade.

6. 6. The brake unit according to claim 5, wherein the blade includes two fork arms spaced apart from each other, the two fork arms contacting two opposing side walls of the receiving groove, respectively.

7. 6. The brake unit according to claim 5, characterized in that the number of the blades is six, the six blades are equally spaced apart on the outer edge of the brake disc, and the number and positions of the accommodating grooves correspond one-to-one to the number and positions of the blades.

8. 2. The brake unit according to claim 1, wherein the brake discs are made of a metallic material and the friction plates are made of a non-metallic material.

9. 2. The brake unit according to claim 1, wherein the motor rotor is provided with a ring-shaped second positioning boss, and one side of the bearing abuts against the second positioning boss.

10. 2. The brake unit according to claim 1, wherein the baffle is provided with a stopper projection extending in an axial direction, the armature is provided with a notch corresponding to the stopper projection, and the baffle is fixed to the electromagnet assembly by a screw extending through the stopper projection.

11. 2. The brake unit according to claim 1, wherein the electromagnet assembly includes a case and an electromagnet housed in the case, the case including an inner ring and an outer ring, the inner ring being fixedly fitted in the bearing, the outer ring being fixed to the baffle, and the electromagnet being housed between the inner ring and the outer ring.

12. The brake unit according to claim 11, wherein the spring assembly is mounted to the outer ring.

13. 13. The brake unit according to claim 12, wherein the outer ring has an accommodation hole, the spring assembly includes a spring and an adjustment screw, the adjustment screw is movably positioned within the accommodation hole, and one end of the spring abuts against the adjustment screw and the other end abuts against the armature.

14. 14. The brake unit according to claim 13, further comprising a gasket disposed between the spring and the adjusting screw.

15. 12. The brake unit according to claim 11, wherein a surface of the bearing is coated with a second adhesive layer.

16. 12. The brake unit according to claim 11, wherein the bearing is a deep groove ball bearing.

17. 2. The brake unit of claim 1, wherein when the electromagnet assembly is energized, a gap between the baffle and the armature is greater than a thickness of the friction plate.

18. A joint drive device, A joint drive device comprising a motor and a brake unit according to any one of claims 1 to 17.

19. A robot, A robot comprising the joint drive device according to claim 18.

20. 20. The robot according to claim 19, further comprising a plurality of robot arms and a plurality of joints, the plurality of robot arms being connected in series, adjacent robot arms being connected by the joints, and the joints being provided with the joint drive devices.

Images