Small robot arm joint and robot

Abstract

The present invention provides a small robot arm joint and a robot using the same. In the small robot arm joint of the present invention, a plurality of bearings are provided at both ends and the middle of the motor shaft, a sliding seal is added between the harmonic reducer and the motor, a seal is fitted and attached to the contact surface between the rigid circular spline and the output end and the contact surface between the rigid circular spline and the housing, the control board and the output end are both hollow structures through which cables pass, a magnetic encoder is used to miniaturize the joint, and a magnetic shielding sheet is attached on the housing separating the motor and the control board. The robot of the present invention uses the small robot arm joint to connect between robot arms. The present invention realizes a small robot arm joint and a robot using the same that has a compact structure, operates smoothly, is safe and reliable. The smoothness of the rotating shaft can be effectively improved. It can also effectively prevent the intrusion of lubricating grease into the inside of the motor or the control board.

Description

[Technical Field]

[0001] The present invention relates to the field of robotics, and more particularly to a miniature robot arm joint and the robot. [Background technology]

[0002] A robot arm joint unit includes a motor, a harmonic reducer, a unit housing, and an encoder. To ensure the harmonic reducer operates effectively, an appropriate amount of lubricating grease must be added between the rigid circular spline and flexspline of the harmonic reducer. However, when the joint unit is in operation, improper structural design can cause grease to infiltrate electrical components such as the motor and encoder, seriously affecting their safety and reliability. Furthermore, poor sealing can cause grease to leak out of the housing, resulting in wasted grease and contaminating the robot arm. In conventional designs, the motor input shaft and the support at the fixed end of the housing are located in two locations, close to each other and far from the motor output end, which can easily cause instability in the motor input shaft. Furthermore, when designing a hollow cable routing hole, a single large hole is typically drilled, through which both the power and signal lines pass, resulting in the power line easily interfering with the signal transmission.

[0003] Therefore, a new joint structure is needed to solve the above problems. Summary of the Invention [Problem to be solved by the invention]

[0004] In response to the need for a new joint structure to solve the above problems, the present invention provides a small robot arm joint that has a compact structure, operates smoothly, is safe, and is highly reliable, and a robot using the joint. [Means for solving the problem]

[0005] Specifically, the present invention provides a small robot arm joint in which the motor, the harmonic reducer, and the control board are separated into different spaces by a housing. The small robot arm joint also includes the following structures:

[0006] The motor shaft is coaxially connected to the housing by bearings A and C, and the harmonic reducer is separated from the motor by the housing and bearing C. A sliding seal is added to the gap between the separated housing and the motor shaft. The sliding seal consists of a plastic seal and an O-ring. The O-ring contacts the housing, and the plastic seal contacts the surface of the motor shaft. Retaining rings are installed on both sides of the plastic seal for axial positioning. Bearings B and D are installed between the left and right ends of the motor shaft and the output end. The inner rings of bearings B and D are fixed to the output end, and the outer rings are fixed to the groove surface of the motor shaft. The radial dimension of the groove surface is larger than the radial dimension of the shaft bore surface of the motor shaft, and the inner rings of bearings B and D are approximately level with the shaft bore surface of the motor shaft.

[0007] The rigid circular spline of the harmonic reducer is mechanically fixedly connected to the output end, and the outer diameter of the rigid circular spline is the maximum outer diameter of the joint unit. Seals are fitted and attached to the contact surfaces between the rigid circular spline and the output end and between the rigid circular spline and the housing.

[0008] The rotor of the motor is connected to the motor shaft by a flat key, and the stator of the motor is fixedly connected to the housing. The left end of the rotor of the motor is positioned by the shaft shoulder on the side closer to the harmonic reducer, and the right end is positioned axially by a spacer ring.

[0009] The control board is mechanically fixed to the housing, and both the control board and the output terminal have hollow structures through which cables pass. Two magnetic encoders are fixed to the control board by electrical connections, and the magnetic disk corresponding to encoder sensor tab A is fixedly connected to the motor shaft, and the magnetic ring corresponding to encoder sensor tab B is fixedly connected to the shaft of the output terminal.

[0010] Two cable holes are formed in the shaft of the output end, and the power line and signal line of the joint unit are passed through one cable hole each.

[0011] A magnetic isolation sheet is mounted on the housing to provide separation between the motor and the control board.

[0012] The bearings B and D are deep groove ball bearings with seal rings on both sides.

[0013] The robot realized by the present invention uses the small robot arm joints to connect the robot arms.

[0014] The advantages and favorable effects of the present invention over the prior art are as follows:

[0015] (1) The robot arm joint of the present invention has two bearings B and D installed between the left and right ends of the motor shaft and the output end, and two bearings A and C installed in the middle of the motor shaft, providing multiple support points, thereby effectively improving the smoothness of the rotating shaft. At the same time, bearings B and D are deep groove ball bearings with double seal rings, which also serve to prevent the lubricating grease of the harmonic reducer from flowing into the right control board along the gap between the motor shaft and the output end, thereby avoiding grease contamination of the control board and causing short circuits, etc.

[0016] (2) In the robot arm joint according to the present invention, a sliding seal is disposed between the electric motor and the reducer, thereby effectively preventing the intrusion of lubricating grease into the electric motor.

[0017] (3) In the robot arm joint according to the present invention, the maximum outer diameter of the rigid circular spline is the same as the maximum outer diameter of the joint unit, eliminating the need to provide an additional housing on the outside of the rigid circular spline. By cooperating with the seal, it is possible to effectively prevent impurities from entering the reducer from the outside and to prevent the lubricating grease inside from leaking out, which would result in grease waste or contamination.

[0018] (4) In the robot arm joint of the present invention, the rotor of the motor is connected to the motor shaft by a flat key, and the left end of the rotor of the motor is harmonics. reducer Positioned by the shaft shoulder of the motor shaft on the side closest to reducer The flat key is positioned axially on the side away from the rotor by a spacer ring, and the side of the flat key and the mounting groove of the motor shaft and the rotor are all transition fits. By using this connection method, disassembly and installation are easy and installation is reliable.

[0019] (5) The outer rings of bearings B and D designed according to the present invention are fixed to the groove surface of the motor shaft, and the radial dimension of the groove surface is much larger than the radial dimension of the shaft hole surface of the motor shaft. Therefore, the installation of bearings B and D does not increase the radial dimension of the entire joint, and the overall structure of the joint is more compact than that of conventional designs.

[0020] (6) In this invention, a magnetic shielding sheet is added between the motor and the control board, and the motor shaft is made of aluminum alloy, a non-magnetic conductive material. These two solutions can significantly reduce the electromagnetic interference between the motor and the control board.

[0021] (7) In the present invention, a magnetic encoder is used, which has superior interference resistance and vibration resistance compared to a photoelectric encoder, and can reduce the structural volume of the entire joint unit.

[0022] (8) The output shaft of the present invention is designed with a two-hole structure, allowing the power line and signal line of the joint unit to be routed separately. This design effectively prevents the power line from interfering with the signal line. [Brief explanation of the drawings]

[0023] [Figure 1] FIG. 1 is a schematic diagram of the internal structure of a robot arm joint provided by the present invention.

[0024] [Figure 2] FIG. 2 is an enlarged view of the interior of circle A of a robot arm joint provided by the present invention.

[0025] [Figure 3] FIG. 3 is a schematic diagram of the structure of the robot provided by the present invention.

[0026] [Explanation of symbols]

[0027] 1 - output end, 1.1 - cable hole A, 1.2 - cable hole B, 2 - motor shaft, 2.1 - inner groove surface A of the motor shaft,

[0028] 2.2 - shaft hole surface of the motor shaft, 2.3 - inner groove surface B of the motor shaft, 3 - wave generator, 3.1 - inner mounting surface, 4 - flexspline, 5 - rigid circular spline,

[0029] 6 - motor stator, 7 - housing A, 8 - motor rotor, 9 - flat key, 10 - magnetic blocking sheet, 11 - housing B, 12 - encoder sensor tab A,

[0030] 13 - magnetic disk, 14 - control board, 15 - encoder sensor tab B, 16 - magnetic ring, 17 - bearing A, 18 - bearing B, 19 - cover plate,

[0031] 20 - bearing C, 21 - bearing D, 22 - seal A, 23 - seal B, 24 - sliding seal, 24.1 - seal plastic,

[0032] 24.2 - O-ring, 25 - retaining ring A, 26 - spacer ring, 27 - retaining ring B, 28 - joint unit, 29 - robot arm A, 30 - robot arm B,

[0033] 31 - Robot arm C, 32 - Robot arm D, 33 - Robot arm E, 34 - Robot arm F. DETAILED DESCRIPTION OF THE INVENTION

[0034] The present invention will now be described in more detail with reference to the accompanying drawings and embodiments.

[0035] An object of the present invention is to provide a small robot arm joint that has a compact structure, operates smoothly, is safe, and is highly reliable, and to provide a robot using the same.

[0036] As shown in FIG. 1, a robot arm joint realized by an embodiment of the present invention has the following configuration.

[0037] (1) The output end 1 has a shaft structure coaxial with the motor shaft 2, and two cable holes, namely, cable hole A1.1 and cable hole B1.2, are opened on the shaft of the output end 1. This cable hole structure allows the power line and signal line of the joint unit to be routed separately, and this design can effectively prevent electromagnetic interference between the power line and the signal line.

[0038] (2) The reducer according to the present invention is a harmonic reducer including a wave generator 3, a flexspline 4, and a rigid circular spline 5. The flexspline 4 engages with the rigid circular spline 5 via its teeth, resulting in high transmission efficiency. The outer diameter of the rigid circular spline 5 in the present invention is the maximum outer diameter of the joint unit, eliminating the need for an additional housing outside the rigid circular spline for fixing it to the robot arm. The wave generator 3 functions as a torque input end and transmits torque to the rigid circular spline 5 via the flexspline 4. The rigid circular spline 5 is mechanically fixedly connected to the output end 1. In the present invention, the engagement of seals A22 and B23 at the contact surfaces between the rigid circular spline 5 and the output end 1 and between the rigid circular spline 5 and the housing A7 effectively prevents external impurities from entering the reducer and also prevents the leakage of lubricating grease inside.

[0039] The seal used in the present invention may have a circular or rectangular structure, and the shape is not limited.

[0040] (3) The motor is separated from the harmonic reducer and control board by the housing and located in different spaces. The motor includes a motor stator 6 and a motor rotor 8. The motor rotor 8 is connected to the motor shaft 2 by a flat key 9, and both ends are fixed axially by shaft shoulders and spacer rings 26. This connection method is easy to disassemble and install, and installation is reliable. The motor stator 6 is fixedly connected to the housing A7 without limiting the connection method. The left end of the motor rotor 8 is positioned on the side closer to the harmonic reducer by the shaft shoulder of the motor shaft 2, and the right end of the motor rotor 8 is positioned axially on the side farther from the harmonic reducer by the spacer ring 26. The side of the flat key 9, the mounting groove of the motor shaft 2, and the rotor mounting groove all have a transition fit.

[0041] (4) In the present invention, the wave generator 3 is mechanically fixedly connected to the motor shaft 2, and this motor shaft 2 is fixedly connected to the rotor 8 of the motor, thereby connecting the wave generator 3 coaxially with the rotor 8 of the motor.

[0042] (5) In the present invention, a magnetic shielding sheet 10 is added. The electric motor generates a certain amount of electromagnetic interference during operation. To prevent the electric motor from interfering with the communication of the right control board 14, the present invention uses the following two preventive measures. One is to add a magnetic shielding sheet 10 between the electric motor and the control board 14, and the magnetic shielding sheet 10 is mechanically fixedly connected to the housing B11. The other is to make the electric motor shaft 2 out of a non-magnetic aluminum alloy. These two options can significantly reduce the electromagnetic interference of the electric motor with the control board 14. The housing A7 and the housing B11 refer to different parts of the housing, and the different parts of the housing are numbered for ease of explanation.

[0043] (6) The present invention uses a magnetic encoder. Compared with the currently commonly used photoelectric encoder, the magnetic encoder has a faster rotation speed, is easier to use, is more resistant to vibration, has a faster response speed, and is highly suitable for use in situations with limited installation space. The magnetic encoder is fixed to the control board 14 via electrical connections. The present invention has two magnetic encoders: one is encoder sensor tab A12 and the other is encoder sensor tab B15. The magnetic disk 13 corresponding to encoder sensor tab A12 is fixedly connected to the motor shaft 2 and is coaxially connected. The magnetic ring 16 corresponding to encoder sensor tab B15 is fixedly connected to the shaft of the output end 1 and is also coaxially connected. The encoder sensor tab A12 is used to detect the speed of the motor input end, and the encoder sensor tab B15 is used to detect the speed of the output end.

[0044] (7) In the present invention, the control board 14 is mechanically and fixedly connected to the housing B11. The control board 14 has a hollow structure, and the output terminal 1 also has a hollow structure, so that the cable can pass through the hollow structure. This structural design makes it possible to make the entire joint unit more compact.

[0045] In addition, in order to prevent interference of the reducer grease with the control board 14, in the embodiment of the present invention, a protective adhesive may be applied to the surface of the control board 14.

[0046] (8) In the present invention, the motor shaft 2 is coaxially connected to the housing A7 by the bearings A17 and C20. A The reducer is separated from the housing A7 by bearing C20. Because grease is sealed in the reducer, in this invention, a sliding seal 24 is added to the gap between the housing A7 and the motor shaft 2 between the reducer and the motor to prevent the grease from entering the motor. The sliding seal 24 is composed of two components: a plastic seal 24.1 and an O-ring 24.2. The O-ring 24.2 is brought into contact with the fixed housing A7 to prevent dynamic wear and extrusion damage to the O-ring 24.2. The plastic seal 24.1 contacts the surface of the motor shaft 2 and is positioned axially on both the left and right sides by snap rings A25 and B27. The plastic seal 24.1 is made of wear-resistant TFE (tetrafluoroethylene), and the O-ring 24.2 is made of oil-resistant nitrile rubber, effectively improving sealing performance.

[0047] (9) In order to improve the rotational stability of the motor shaft 2, the present invention adds bearing support to the motor shaft 2, and designs bearings B18 and D21 between the left and right ends of the motor shaft 2 and the output end 1. The inner ring of bearing D21 is fixed to the output end 1, and the outer ring is fixed to the inner mounting surface 3.1 of the wave generator 3 and the groove surface A2.1 inside the motor shaft 2. Groove surface AThe radial dimension of bearing B18 is much larger than that of bore surface 2.2 of the motor shaft, placing the inner ring of bearing D21 at approximately the same level as bore surface 2.2. In conventional designs, the outer ring of bearing D21 is sometimes flush with bore surface 2.2. In contrast, the design of this invention reduces the radial dimension of the entire joint. The inner ring of bearing B18 is fixed to output end 1, and its outer ring is fixed to groove surface B2.3 of motor shaft 2. Because the radial dimension of groove surface B2.3 is much larger than that of bore surface 2.2, the installation of bearing B18 does not increase the radial dimension of the entire joint, making the overall structure more compact. Motor shaft 2 can rotate freely around output end 1. Bearings B18 and D21 also prevent lubricating grease from the harmonic reducer from flowing into the right control board 14 along the gap between motor shaft 2 and output end 1. Preferably, in the embodiment of the present invention, bearings B and D adopt deep groove ball bearings with double seal rings.

[0048] The motor shaft of the present invention has four support points, bearings A to D, with bearings A and C located in the middle of the motor shaft and bearings B and D located at both ends, and the multiple support points can effectively improve the smoothness of the rotating shaft.

[0049] (10) In the present invention, the cover plate 19 is mechanically and fixedly connected to the housing B11 to prevent dust, impurities, etc. from entering the electrical components. The cover plate 19 is made of aluminum, which has a good heat dissipation effect.

[0050] As shown in Figure 2, the robot realized by the embodiment of the present invention is composed of robot arm A29, robot arm B30, robot arm C31, robot arm D32, robot arm E33, robot arm F34 and each joint unit 28. The robot arms are connected to each other by joint units 28 or connectors. 4 A load may be fixedly connected to the joint units 28 of the robot arm to move or rotate the load. Each joint unit 28 of the robot arm has the functions of the robot joint units described above, and a description thereof will be omitted here.

[0051] The above description provides a miniature robot arm joint and a robot thereof. It should be understood that the embodiments described above do not represent all embodiments consistent with the present invention, and that various modifications or variations that can be made by those skilled in the art based on the technical scheme of the present invention without requiring creative effort still fall within the scope of protection of the present invention.

[0052] All technical features other than those described in the specification are known to those skilled in the art, and in the present invention, descriptions of known components and known techniques are omitted to avoid redundancy and unnecessary limitations of the present invention.

Claims

1. The housing separates the motor, harmonic reducer, and control board into different spaces, The motor shaft is coaxially connected to the housing by bearings A and C, and the harmonic reducer is separated from the motor by the housing and bearing C. A sliding seal is added in the gap between the separated housing and the motor shaft. Separation means that the housing is separated into two parts, and the motor shaft connects the two parts via bearings A and C. The sliding seal is made of a sealing plastic and an O-ring. The O-ring contacts the housing, and the sealing plastic contacts the surface of the motor shaft. Retaining rings are provided on both sides of the sealing plastic to position it in the axial direction. bearings B and D are attached between both ends of the motor shaft and the output end, bearing B is attached between one end of the motor shaft and one connection part of the output end, bearing D is attached between the other end of the motor shaft and the other connection part of the output end, inner rings of bearings B and D are fixed to the output end and outer rings are fixed to the groove surface of the motor shaft, the radial dimension of said groove surface is larger than the radial dimension of the shaft hole surface of the motor shaft, the inner rings of bearings B and D are at approximately the same height as the shaft hole surface of the motor shaft, said output end is an output structure that performs the output function of the robot arm joint, and the groove surface is the inner concave surface of the groove, the rigid circular spline of the harmonic reducer is mechanically fixedly connected to the output end, the outer diameter of the rigid circular spline is the maximum outer diameter of the robot arm joint, and seals are fitted and attached to contact surfaces between the rigid circular spline and the output end and between the rigid circular spline and the housing; the rotor of the motor is connected to the motor shaft by a flat key, the stator of the motor is fixedly connected to the housing, one end of the rotor of the motor is positioned by a shaft shoulder of the motor shaft on a side closer to the harmonic reducer, and the other end is positioned in the axial direction by a spacer ring, and the spacer ring maintains an axial space between the other end of the motor rotor and bearing A; a control board mechanically and fixedly connected to the housing, the control board and the output end both having a hollow structure through which a cable passes, a first magnetic encoder and a second magnetic encoder are fixed to the control board by electrical connection, the first magnetic encoder includes an encoder sensor tab A and a magnetic disk fixedly connected to the motor shaft, and the second magnetic encoder includes an encoder sensor tab B and a magnetic ring fixedly connected to the shaft of the output end, the encoder sensor tab A detects magnetic changes in the magnetic disk, and the encoder sensor tab B detects magnetic changes in the magnetic ring.

2. 2. The robot arm joint according to claim 1, wherein two cable-passing holes are opened in the shaft of the output end, and the power line of the robot arm joint is passed through one hole and the signal line is passed through the other hole.

3. 3. A robot arm joint according to claim 1, wherein the side surface of the flat key, the mounting groove of the motor shaft, and the mounting groove of the rotor are all transition fit.

4. 3. The robot arm joint according to claim 1, wherein a magnetic shielding sheet is attached on the housing separating the motor and the control board.

5. 5. The robot arm joint according to claim 4, wherein the motor shaft is made of a non-magnetic aluminum alloy.

6. 5. The robot arm joint according to claim 4, wherein a protective adhesive is applied to the surface of the control board.

7. 3. A robot arm joint according to claim 1, wherein the bearings B and D are deep groove ball bearings with seal rings on both sides.

8. 3. The robot arm joint according to claim 1, wherein the housing has an opening for accommodating a control board, and is mechanically and fixedly connected to a cover plate that seals the opening.

9. A robot, characterized in that robot arms are connected using the robot arm joint according to claim 1 or 2.

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