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 technology, and more particularly to a miniature robot arm joint and the robot. [Background technology]

[0002] The robot arm joint unit includes an electric motor, a harmonic reducer, a unit housing, and an encoder, etc. In order to ensure the effective operation of the harmonic reducer, it is necessary to add an appropriate amount of lubricating grease between the rigid circular spline and the flex spline of the harmonic reducer. However, when the joint unit is working, due to an unreasonable structural design, the grease will enter the electric components such as the electric motor and the encoder, which will seriously affect the safety and reliability of the electric components. In addition, if the sealing is poor, the grease will flow outside the housing, which will waste the grease and contaminate the robot arm. In the conventional design, the input shaft of the electric motor and the support part of the fixed end of the housing are located in two places, the distance between the two places is close, and the support part is far from the output end of the electric motor, which makes the input shaft of the electric motor easy to become unstable. In addition, when designing a cable passage hole with a hollow structure, it is common to machine one large hole and pass the power line and the signal line through the cable passage hole together, which makes it easy for the power line to interfere with the transmission signal of the signal line.

[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-sized robot arm joint that has a compact structure, operates smoothly, and is safe and reliable, and a robot using the joint. [Means for solving the problem]

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

[0006] The motor shaft is coaxially connected to the housing by bearings A and C, the harmonic reducer is separated from the motor by the housing and bearing C, and a sliding seal is added in the gap between the separated housing and the motor shaft. The sliding seal is made of a sealing plastic and an O-ring. The O-ring contacts the housing, the sealing plastic contacts the surface of the motor shaft, and retaining rings are provided on both the left and right sides of the sealing plastic for axial positioning. Bearings B and D are installed between the left and right ends of the motor shaft and the output end, with the inner rings of bearings B and D fixed to the output end and the outer rings 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 hole surface of the motor shaft, and the inner rings of bearings B and D are approximately level with the shaft hole 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 motor rotor is positioned by the shaft shoulder of the motor shaft on the side closer to the harmonic reducer, and the right end is positioned in the axial direction by a spacer ring.

[0009] The control board is mechanically fixedly connected to the housing, and both the control board and the output end 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 end.

[0010] Two cable holes are opened 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 between the left and right ends of the motor shaft and the output end, and two bearings A and C in the middle of the motor shaft, providing multiple support points, which effectively improves the smoothness of the rotating shaft. At the same time, bearings B and D are deep groove ball bearings with double-sided seal rings, which prevents 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 preventing the control board from being contaminated by grease and causing a short circuit, etc.

[0016] (2) In the robot arm joint according to the present invention, by disposing a sliding seal between the electric motor and the reducer, it is possible to effectively prevent lubricating grease from entering the inside of 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 maximum outer diameter of the joint unit, and there is no 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 inside of the reducer from the outside and to prevent the internal lubricating grease from leaking out, which would result in grease waste and 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, the left end of the motor rotor is positioned by the shaft shoulder of the motor shaft on the side closer to the harmonics, and is positioned in the axial direction by a spacer ring on the side farther from the harmonics, and the side of the flat key, the mounting groove of the motor shaft, and the mounting groove of the rotor are all transition fits. By using such a connection method, disassembly and installation are easy and installation is reliable.

[0019] (5) The bearings B and D designed according to the present invention have their outer rings 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 the 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 the conventional design.

[0020] (6) In the present invention, a magnetic shielding sheet is added between the motor and the control board, and the motor shaft is made of aluminum alloy, which is a non-magnetic conductive material. These two solutions can significantly reduce the electromagnetic interference of the motor with 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 end shaft of the present invention is designed with a two-hole structure, so that the power line and the signal line of the joint unit can be passed through separately. This design can effectively avoid the electromagnetic interference of the power line with the signal line. [Brief description 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] [Diagram 2] FIG. 2 is a close-up view of the interior at circle A of a robot arm joint provided by the present invention.

[0025] [Diagram 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 seat, 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 PREFERRED EMBODIMENTS

[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-sized robot arm joint that has a compact structure, operates smoothly, and is safe and reliable, and a robot using the same.

[0036] As shown in FIG. 1, a robot arm joint realized according to 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 wired separately, and this design can effectively avoid the electromagnetic interference of the power line with 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 meshes with the rigid circular spline 5 with teeth, and has 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, and there is no need to add a housing outside the rigid circular spline to fix it to the robot arm. The wave generator 3 functions as a torque input end and transmits torque to the rigid circular spline 5 through the flexspline 4. The rigid circular spline 5 is mechanically fixedly connected to the output end 1. In the present invention, the seal A22 and the seal B23 are fitted to each other at the contact surface between the rigid circular spline 5 and the output end 1 and the contact surface between the rigid circular spline 5 and the housing A7, thereby effectively preventing external impurities from entering the reducer, and also preventing the lubricating grease inside from leaking out.

[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 the 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 in the axial direction 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 by the shaft shoulder of the motor shaft 2 on the side closer to the harmonic reducer, and the right end of the motor rotor 8 is positioned in the axial direction by the spacer ring 26 on the side farther from the harmonic reducer. The side of the flat key 9, the mounting groove of the motor shaft 2, and the mounting groove of the rotor are all transition fits.

[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 will generate a certain amount of electromagnetic interference during operation. In order 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 made of a non-magnetic aluminum alloy. These two options can greatly reduce the electromagnetic interference of the electric motor to the control board 14. Wherein, the housing A7 and the housing B11 refer to different parts of the housing, and the different parts of the housing are numbered for convenience of explanation.

[0043] (6) The present invention uses a magnetic encoder, which, compared with the currently mainly used photoelectric encoder, has a high rotation speed, is easy to use, is resistant to vibration, has a fast response speed, and is very suitable for use in situations with a small installation space. The magnetic encoder is fixed to the control board 14 by electrical connection. There are two magnetic encoders in the present invention, one is the encoder sensor tab A12 and the other is the encoder sensor tab B15. The magnetic disk 13 corresponding to the encoder sensor tab A12 is fixedly connected to the motor shaft 2 and is connected coaxially. The magnetic ring 16 corresponding to the encoder sensor tab B15 is fixedly connected to the shaft of the output end 1 and is also connected coaxially. 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) The control board 14 in the present invention is mechanically fixedly connected to the housing B11. The control board 14 has a hollow structure, and the output end 1 also has a hollow structure, and the cable can pass through the hollow structure. This structural design makes it possible to make the structure of 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 bearing A17 and the bearing C20. The reducer and the motor are separated by the housing 7 and the bearing C20. Since the reducer is filled with grease, in the present 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 inside of the motor. The sliding seal 24 is composed of two parts, a sealing plastic 24.1 and an O-ring 24.2. In order to prevent dynamic wear and extrusion destruction of the O-ring 24.2, the O-ring 24.2 is brought into contact with the fixed housing A7. The sealing plastic 24.1 contacts the surface of the motor shaft 2 and is axially positioned on both the left and right sides by the retaining rings A25 and B27. The sealing plastic 24.1 is made of wear-resistant TFE (tetrafluoroethylene), and the O-ring 24.2 is made of oil-resistant nitrile rubber, which can effectively improve the sealing performance.

[0047] (9) In order to improve the rotation 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 the 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. The radial dimension of the groove surface 2.1 is much larger than the radial dimension of the shaft hole surface 2.2 of the motor shaft, making the inner ring of the bearing D21 almost level with the shaft hole surface 2.2. In the existing conventional design, the outer ring of the bearing D21 may be level with the shaft hole surface 2.2, compared with this, the design of the present invention makes the radial dimension of the entire joint smaller. The inner ring of the bearing B18 is fixed to the output end 1, and the outer ring is fixed to the groove surface B2.3 of the motor shaft 2. Since the radial dimension of the groove surface B2.3 is much larger than that of the shaft hole surface 2.2, the installation of the bearing B18 does not increase the radial dimension of the entire joint, making the overall structure more compact. The motor shaft 2 can rotate freely around the output end 1. In addition, the bearing B18 and the bearing D21 also play a role in preventing the lubricating grease of the harmonic reducer from flowing into the right control board 14 along the gap between the motor shaft 2 and the output end 1. Preferably, in the embodiment of the present invention, the bearing B and the bearing D adopt deep groove ball bearings with double-sided sealing 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 position 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 and prevents 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 Fig. 2, a robot realized by an embodiment of the present invention is composed of a robot arm A29, a robot arm B30, a robot arm C31, a robot arm D32, a robot arm E33, and a robot arm F34, and each joint unit 28. The robot arms are connected to each other by the joint units 28 or connectors. A load may be fixedly connected to the robot arm F33 at the end to realize movement or rotation of the load. Each joint unit 28 of the robot arm has the function of the robot joint unit 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 above-described embodiments do not represent all embodiments consistent with the present invention, and various modifications or variations that can be made by those skilled in the art based on the technical scheme of the present invention without creative effort are still within the scope of protection of the present invention.

[0052] All the technical features other than those described in the specification are known to those skilled in the art. 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, 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, the sliding seal is made of a sealing plastic and an O-ring, the O-ring is in contact with the housing, the sealing plastic is in contact with the surface of the motor shaft, retaining rings are provided on both the left and right sides of the sealing plastic 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 hole surface of the motor shaft, and the inner rings of bearings B and D are approximately level with the shaft hole surface of the motor shaft, 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 joint unit, and a seal is fitted and attached to a contact surface between the rigid circular spline and the output end and a contact surface 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, the left end of the rotor of the motor is positioned by a shaft shoulder of the motor shaft on the side close to the harmonic reducer, and the right end is positioned in the axial direction by a spacer ring; a control board is mechanically and fixedly connected to a housing, the control board and the output end both have a hollow structure through which a cable passes, two magnetic encoders are fixed to the control board by electrical connections, a magnetic disk corresponding to encoder sensor tab A is fixedly connected to an electric motor shaft, and a magnetic ring corresponding to encoder sensor tab B is fixedly connected to a shaft of the output end.

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

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-fitted.

4. 3. The robot arm joint according to claim 1 or 2, characterized in that a magnetic shielding sheet is mounted on the housing separating the motor and the control board.

5. 5. A 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. A robot arm joint according to claim 1 or 2, characterized in that the housing is mechanically and fixedly connected to one cover plate.

9. A robot, comprising robot arms connected together using the robot arm joint according to claim 1 or 2.

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