An electric rotating joint for a robotic arm

Abstract

The present invention relates to an electric rotating joint of a robotic arm, belonging to the technical field of underwater robots. The electric rotating joint of the robotic arm comprises a cylinder body, an end cover, an outer rotor motor, a rotating shaft and a rotating external connection part. The power output end of the outer rotor motor is provided with an external flange, and a flange plate is arranged on the rotating shaft. The flange plate is connected to the external flange. The outer rotor motor is installed on the end cover, the end cover covers the opening of the cylinder body and the outer rotor motor is placed inside the cylinder body. One end of the rotating shaft passes through the outer rotor motor and extends out of the bottom of the cylinder body, and the other end of the rotating shaft passes through the end cover and extends out. The rotating external connection part is connected to the end of the other end of the rotating shaft, and the axial pressures received by both ends of the rotating shaft are the same. Through the above structure, when the electric rotating joint of the robotic arm provided by the present invention is placed in a medium, the pressures received by both ends of the rotating shaft are the same, so it can be applied to deep-sea robots, and its structure is simple and the cost is lower.

Description

Technical Field

[0001] The present invention belongs to the technical field of underwater robots, and particularly relates to an electric rotating joint for a robotic arm. Background Art

[0002] With the increasing development of the ocean to deeper depths, more diverse underwater operations have emerged. Underwater robots have become one of the essential tools. The robotic arms equipped on underwater robots are mainly used for tasks such as resource collection and sample acquisition. Tools in shallow waters can no longer meet people's exploration and development of deeper waters. Currently, most deep-sea underwater robotic arm joints adopt a hydraulic form. Each joint needs to be equipped with a hydraulic cylinder, and a hydraulic pump station needs to be set up for the supply of hydraulic oil. The weight is relatively large, making it not suitable for being carried by small and medium-sized underwater robots.

[0003] The patent application with the publication number CN110253618A discloses a modular underwater robotic arm joint driven by an electric motor. This robotic arm joint mainly consists of a waterproof stepper motor, a waterproof multi-core connector, an output shaft, a cable, a fixing part, and a threaded connector, etc. It can be seen that in this patented technology, the purpose of rotational motion is achieved by connecting the output shaft with a waterproof stepper motor, and the connection with other joints is realized through threaded connectors. However, the robotic arm joint disclosed in this patent has the disadvantages of complex structure and high cost. Summary of the Invention

[0004] The present invention provides an electric rotating joint for a robotic arm to solve the technical problems of complex structure and high cost existing in the robotic arm joints for deep sea in the prior art.

[0005] The present invention is realized through the following technical solutions: An electric rotating joint for a robotic arm includes a cylinder body, an end cover, an outer rotor motor, a rotating shaft, and a rotating external connection part. The power output end of the outer rotor motor has an external flange. A flange disk is coaxially arranged on the rotating shaft, and the flange disk is connected to the external flange. The outer rotor motor is installed on the end cover. The end cover covers the opening of the cylinder body and the outer rotor motor is placed inside the cylinder body. One end of the rotating shaft passes through the outer rotor motor and extends out of the bottom of the cylinder body, and the other end of the rotating shaft passes through the end cover and extends out. The rotating external connection part is connected to the end of the other end of the rotating shaft, and the axial pressures on both ends of the rotating shaft are the same.

[0006] Further, to better implement the present invention, the two ends of the rotating shaft are respectively an A end passing through the outer rotor motor and a B end passing through the end cover. The outer diameter of the A end is smaller than the outer diameter of the B end;

[0007] A first bearing chamber is provided at the bottom of the cylinder body. The A end extends into the first bearing chamber. A first bearing is installed in the first bearing chamber, and the rotating shaft is fitted and inserted into the first bearing;

[0008] A piston adapted thereto is installed in the first bearing chamber. The piston is sleeved on the A end, and further includes a baffle for preventing the piston from moving out of the first bearing chamber. The baffle is installed on the end wall of the first bearing chamber, and a through hole is provided on the baffle.

[0009] The end face area of one end of the piston close to the baffle is the same as the end face area of the B end.

[0010] Further, to better implement the present invention, a second bearing chamber is provided on the end cover, and further includes a second bearing. The second bearing is installed in the second bearing chamber, the second bearing chamber is inserted into the cylinder body, and the outer wall of the external flange and the outer wall of the flange plate are both in interference fit with the inner ring wall of the second bearing.

[0011] Further, to better implement the present invention, the first bearing chamber extends out of the bottom of the cylinder body, and the section of the first bearing chamber extending out of the cylinder body forms an installation pipe, and a driven plate is rotatably installed outside the installation pipe.

[0012] The rotary external connection part includes a driving plate and an external connection plate. The driving plate is vertically connected to the end of the B end, the external connection plate is connected to the driving plate, and the driven plate is connected to the external connection plate.

[0013] Further, to better implement the present invention, a sliding bearing is further included. The sliding bearing is sleeved outside the installation pipe, and the driven plate is connected to the sliding bearing.

[0014] Further, to better implement the present invention, an external connection block is detachably and fixedly installed on the outer wall of the cylinder body.

[0015] Further, to better implement the present invention, an annular groove coaxial with the cylinder body is provided on the outer wall of the cylinder body. The external connection block is provided with a first arc-shaped plate adapted to the annular groove. A second arc-shaped plate is further included. The second arc-shaped plate and the first arc-shaped plate are connected together by a first screw to form a sleeve structure, and the sleeve structure is sleeved in the annular groove.

[0016] Further, to better implement the present invention, the first arc-shaped plate and the cylinder wall of the cylinder body are connected together by a second screw, and the second arc-shaped plate and the cylinder wall of the cylinder body are connected together by a third screw.

[0017] Further, to better implement the present invention, a cable installation hole is further provided at the bottom of the cylinder body. A cable adapter is installed at the edge of the cable installation hole. A cable electrically connected to the outer rotor motor is further included, and the cable is inserted into the cable adapter.

[0018] Furthermore, to better implement the present invention, sealing rings are provided between the outer wall of the second bearing chamber and the inner wall of the cylinder body, between the rotating shaft and the end cover, between the piston and the inner wall of the first bearing chamber, and between the cable adapter and the bottom of the cylinder body.

[0019] The present invention has the following beneficial effects compared with the prior art:

[0020] The robotic arm electric rotating joint provided by the present invention includes a cylinder body, an end cover, an outer rotor motor, a rotating shaft, and a rotating external connection part. The power output end of the outer rotor motor has an external flange. A flange is provided on the rotating shaft, and the flange is connected to the external flange. In this way, the outer rotor motor can drive the rotating shaft to rotate. One end of the rotating shaft passes through the outer rotor motor and extends out. The outer rotor motor is installed on the end cover, and the end cover covers the opening of the cylinder body. At this time, the outer rotor motor is placed in the cylinder body, and the other end of the rotating shaft passes through the end cover and extends out. The rotating external connection part is connected to the end of the other end of the rotating shaft. In this way, the rotating shaft can drive the rotating external connection part to rotate. At this time, the other end of the rotating shaft is outside the cylinder body and the end cover. The end of the rotating shaft passing through the outer rotor motor passes through the bottom of the cylinder body. In this way, both ends of the rotating shaft are outside the cylinder body and the end cover. Moreover, when the robotic arm electric rotating joint is placed in water or air, both ends of the rotating shaft are in the medium, ensuring that the axial pressures exerted on both ends of the rotating shaft by the medium are the same. Through the above structure, when the robotic arm electric rotating joint provided by the present invention is placed in water, both ends of the rotating shaft are in the water, and the axial pressures on both ends of the rotating shaft are the same, thus canceling each other out, preventing the rotating shaft from generating radial offset. Therefore, the water pressure will not affect the outer rotor motor. Therefore, the robotic arm electric rotating joint provided in this embodiment is applicable to deep sea, and its structure is simple and the cost is lower. Description of the Drawings

[0021] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained based on these drawings.

[0022] Figure 1 is a schematic structural diagram of the robotic arm electric rotating joint in the embodiment of the present invention;

[0023] Figure 2 is Figure 1 another perspective view of the structure shown;

[0024] Figure 3 isFigure 1 Cross-sectional view of the structure shown;

[0025] Figure 4 is Figure 3 Partial enlarged view of area A in;

[0026] Figure 5 is Figure 3 Partial enlarged view of area B in;

[0027] Figure 6 is the exploded view when the external connection block in the embodiment of the present invention is installed on the cylinder body.

[0028] In the figure:

[0029] 1 - cylinder body; 2 - end cover; 3 - outer rotor motor; 4 - rotating shaft; 5 - flange; 6 - active plate; 7 - external connection plate; 8 - first bearing chamber; 9 - first bearing; 10 - piston; 11 - baffle; 12 - second bearing chamber; 13 - second bearing; 14 - driven plate; 15 - sliding bearing; 16 - external connection block; 17 - first arc-shaped block; 18 - second arc-shaped block; 19 - first screw; 20 - second screw; 21 - third screw; 22 - cable adapter; 23 - sealing ring; 24 - snap ring; 25 - ring plate. Specific implementation mode

[0030] To make the purpose, technical solutions and advantages of the present invention clearer, the technical solutions of the present invention will be described in detail below. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other implementation manners obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts belong to the scope protected by the present invention.

[0031] Embodiment 1:

[0032] This embodiment provides a robotic arm electric rotating joint, which can be applied to a robotic arm for deep-sea operation.

[0033] The robotic arm electric rotating joint includes a cylinder body 1, an end cover 2, an outer rotor motor 3, a rotating shaft 4 and a rotating connection part. The cylinder body 1 is a straight cylinder structure and has a cylinder opening and a cylinder bottom. Preferably, the cylinder wall and the cylinder bottom of the cylinder body 1 are both made of waterproof materials (such as stainless steel). The end cover 2 is also a structural member made of water-blocking materials. The end cover 2 covers the cylinder opening of the cylinder body 1. Specifically, the end cover 2 is detachably fixedly connected to the cylinder opening of the cylinder body 1 by a fourth screw. At this time, the end cover 2 can seal the cylinder opening of the cylinder body 1.

[0034] The above-mentioned outer rotor motor 3 is installed on the above-mentioned end cover 2, and the outer rotor motor 3 is placed inside the above-mentioned cylinder 1. The power output end of the outer rotor motor 3 has an external flange. The above-mentioned rotating shaft 4 is rotatably inserted inside the outer rotor motor 3, and a flange plate 5 is coaxially provided on the rotating shaft 4. The flange plate 5 is connected to the above-mentioned external flange by a fifth screw. At this time, when the outer rotor motor 3 is powered on and running, it can drive the above-mentioned flange plate 5 and the rotating shaft 4 to rotate in the above-mentioned cylinder 1.

[0035] In this embodiment, one end of the above-mentioned rotating shaft 4 passes through the outer rotor motor 3 and extends out of the bottom of the cylinder 1 of the cylinder, and the other end of the rotating shaft 4 passes through the above-mentioned end cover 2 and extends out. In this way, both ends of the rotating shaft 4 extend out of the above-mentioned cylinder 1 and the end cover 2, and the above-mentioned rotating external connection part is connected to one end of the rotating shaft 4 extending out of the end cover 2. The rotating shaft 4 can drive the rotating external connection part to rotate. It should be noted that the rotating external connection part in this embodiment is actually a component for connecting with an external joint.

[0036] With the above structure, in the robotic arm electric rotating joint provided in this embodiment, both ends of the rotating shaft 4 extend out. In this way, when it is placed in a medium, both ends of the rotating shaft 4 are placed in the medium, and it is defined that the axial pressures received by both ends of the rotating shaft 4 are the same. In this way, the axial pressures exerted by the medium on both ends of the rotating shaft 4 will cancel each other out, so that the rotating shaft 4 will not generate axial offset, and thus will not cause damage to the outer rotor motor 3. With the help of this structure, the robotic arm electric rotating joint provided in this embodiment can be applied to the robotic arm for deep-sea operation, and its structure is simpler and the cost is lower.

[0037] As an optimal implementation manner of this embodiment, the outer rotor motor 3 in this embodiment is a harmonic reduction motor, so that the overall structure is lighter and the load that the rotating external connection part can bear is greater.

[0038] Embodiment 2:

[0039] As an optimal implementation manner of Embodiment 1, in this embodiment, the end of the rotating shaft 4 passing through the outer rotor motor 3 is defined as end A, and the end of the rotating shaft 4 passing through the end cover 2 is defined as end B. Since end A will pass through the above-mentioned outer rotor motor 3 and end B is connected to the above-mentioned rotating external connection part, it is necessary to design the diameter of end B to be larger to output a greater torque, and design the diameter of the above-mentioned end A to be smaller to facilitate its passing through the above-mentioned outer rotor motor 3, that is, the outer diameter of end B is larger than the outer diameter of end A.

[0040] A first bearing chamber 8 is provided at the bottom of the cylinder body 1. A first bearing 9 is installed in the first bearing chamber 8. The A end of the rotating shaft 4 extends into the first bearing chamber 8, and the A end is fitted and inserted into the first bearing 9. In this way, the first bearing 9 plays a role in radially positioning and limiting the A end of the rotating shaft 4, so that the rotating shaft 4 rotates more flexibly.

[0041] A piston 10 is also installed in the first bearing chamber 8. The piston 10 is adapted to the first bearing chamber 8, that is, the piston 10 can slide axially along the rotating shaft 4 in the first bearing chamber 8, and the piston 10 is sleeved on the A end of the rotating shaft 4. A baffle 11 is also installed on the end wall of the first bearing chamber 8. The baffle 11 can block the piston 10 to prevent it from sliding out of the first bearing chamber 8, so that the piston 10 can only slide in the first bearing chamber 8. Preferably, the baffle 11 can seal the first bearing chamber 8, and a through hole is provided in the baffle 11.

[0042] When the robotic arm electric rotating joint provided in this embodiment is placed in a medium, the medium can pass through the through hole in the baffle 11 and enter the first bearing chamber 8 and act on the piston 10. Preferably, the end face area of the end of the piston 10 close to the baffle 11 is the same as the end face area of the B end of the rotating shaft 4. In this way, when the rotating shaft 4 is at the same height or depth in the medium, the pressure exerted by the medium on the B end is the same as the pressure exerted on the piston 10. Since the areas of the two are the same, the axial pressures exerted by the medium on the B end and the piston 10 are the same, and the pressure transmitted by the piston 10 to the A end of the rotating shaft 4 is the same as the pressure received by the B end of the rotating shaft 4. Thus, the pressures received at both ends of the rotating shaft 4 are the same.

[0043] In the above structure, the piston 10 is cleverly used to balance the pressures received at both ends of the rotating shaft 4. The structure is simpler, and the piston 10 can also play a sealing effect, and the rotation of the rotating shaft 4 will not be affected.

[0044] As a more preferred implementation manner of this embodiment, in this embodiment, a shaft step is provided on the section of the rotating shaft 4 close to the A end. The end face of the piston 10 abuts against the end face of the shaft step. Moreover, the shaft step cooperates with the first bearing 9. A snap ring groove is provided on the shaft step, and a snap ring 24 is installed in the snap ring groove. The snap ring 24 presses the first bearing 9 against the inner wall of the first bearing chamber 8, so that the first bearing 9 is firmly installed in the first bearing chamber 8.

[0045] Embodiment 3:

[0046] As a more optimal implementation of Embodiment 2, in this embodiment, a second bearing chamber 12 is further provided on the end cover 2. When the end cover 2 is installed at the barrel opening of the above-mentioned barrel 1, the second bearing chamber 12 is inserted into the interior of the barrel 1, and the outer rotor motor 3 is connected to the free end of the second bearing chamber 12 by a sixth screw.

[0047] A second bearing 13 is fitted and installed in the second bearing chamber 12. The outer wall of the external flange at the power output end of the outer rotor motor 3 and the outer wall of the flange plate 5 are both in interference fit with the inner ring wall of the second bearing 13. With this structure, the rotating shaft 4 and the power output end of the outer rotor motor 3 in this embodiment share a second bearing 13, thus making the structure more compact, and further greatly reducing the volume of the robotic arm electric rotary joint provided in this embodiment.

[0048] As a specific implementation in this embodiment, the robotic arm electric rotary joint provided in this embodiment further includes an annular plate 25. The annular plate 25 is connected to the end wall of the second bearing chamber 12 by a ninth screw, and the housing of the outer rotor motor 3 is connected to the annular plate 25 by a tenth screw. Moreover, an annular boss is provided on the annular plate 25, and the annular boss presses the second bearing 13 in the second bearing chamber 12.

[0049] Embodiment 4:

[0050] As a more optimal implementation of the above embodiment, specifically, in this embodiment, the rotating external connection part includes a driving plate 6 and an external connection plate 7. Among them, the driving plate 6 is connected to the B end of the rotating shaft 4 by key connection and locked by a seventh screw. The external connection plate 7 is provided with through holes and / or threaded holes for connecting with external structures, and the external connection plate 7 is connected to the end of the driving plate 6 away from the rotating shaft 4 by an eighth screw. Optimally, the driving plate 6 is perpendicular to the rotating shaft 4, and the external connection plate 7 is perpendicular to the driving plate 6. At this time, the external connection plate 7 is parallel to the rotating shaft 4. When the rotating shaft 4 rotates, the rotating shaft 4 can drive the driving plate 6 to rotate, and the driving plate 6 can drive the external connection plate 7 to rotate.

[0051] In this embodiment, the first bearing chamber 8 extends out of the bottom of the barrel 1, and the section of the first bearing chamber 8 extending out of the barrel 1 is a round tube and this section forms an installation tube. A driven plate 14 is rotatably sleeved outside the installation tube, and the driven plate 14 is connected to the external connection plate 7. That is, the driving plate 6 and the driven plate 14 are respectively connected to both ends of the external connection plate 7 to form a rotating support. In this way, the rotation of the external connection plate 7 can be ensured to be smoother, and moreover, both ends of the external connection plate 7 have supports, and the load it can bear is greater.

[0052] As a more optimal implementation manner of this embodiment, in this embodiment, a sliding bearing 15 is sleeved outside the above-mentioned mounting pipe, and the above-mentioned driven plate 14 is connected to the sliding bearing 15, that is, the above-mentioned driven plate 14 is connected to the above-mentioned mounting pipe through the sliding bearing 15, so that the rotation of the driven plate 14 on the mounting pipe is more flexible.

[0053] Embodiment 5:

[0054] As a more optimal implementation manner of the above embodiment, in this embodiment, an external connection block 16 is detachably and fixedly installed on the outer wall of the above-mentioned cylinder body 1, and through holes and / or threaded holes for installation are also provided on the external connection block 16. By using the external connection block 16, the cylinder body 1 and the robotic arm electric rotary joint provided in this embodiment can be connected to an external object. In this way, for example, when three such robotic arm electric rotary joints are combined to form a robotic arm, the external connection plate 7 of the first one can be connected to the external connection block 16 of the second one, and then the external connection block 16 of the first one can be connected to the external connection plate 7 of the third one.

[0055] As a specific implementation manner of this embodiment, in this embodiment, an annular groove is provided on the outer wall of the above-mentioned cylinder body 1, the annular groove is coaxial with the above-mentioned cylinder body 1, a first arc-shaped plate 17 adapted to the annular groove is provided on the above-mentioned external connection block 16, and a second arc-shaped plate 18 is further included. The first arc-shaped plate 17 and the second arc-shaped plate 18 are spliced to form a sleeve structure and fastened by a first screw 19. During installation, the above-mentioned sleeve structure is sleeved in the annular groove and the sleeve structure is embedded in the annular groove so that the overall structure is more compact. In this way, the external connection block 16 can be quickly disassembled and assembled from the cylinder body 1.

[0056] As a more optimal implementation manner of this embodiment, in this embodiment, the above-mentioned first arc-shaped plate 17 is connected to the barrel wall of the above-mentioned cylinder body 1 through a second screw 20, and the above-mentioned second arc-shaped plate 18 is connected to the barrel wall of the cylinder body 1 through a third screw 21. In this way, the connection between the first arc-shaped plate 17 and the second arc-shaped plate 18 can be made more firm, so that the external connection block 16 is more firmly connected to the cylinder body 1. Specifically, a plurality of blind holes are provided on the end face of the end of the above-mentioned cylinder body 1 where the first bearing chamber 8 is provided. First screw holes and second screw holes are respectively provided on the end walls of the above-mentioned first arc-shaped plate 17 and the second arc-shaped plate 18. The second screw 20 passes through the corresponding blind hole and is screwed into the above-mentioned first screw hole, and the third screw 21 passes through the corresponding blind hole and is screwed into the above-mentioned second screw hole.

[0057] Embodiment 6:

[0058] As a more optimal implementation manner of the above embodiment, in this embodiment, a cable installation hole is further provided at the bottom of the cylinder body 1. The cable installation hole supplies power to the outer rotor motor 3. A cable adapter 22 is installed at the edge of the cable installation hole. The cable adapter 22 is located outside the cylinder body 1, and the cable adapter 22 is electrically connected to the cable that supplies power to the outer rotor motor 3. That is, through the cable adapter 22, the cable outside the cylinder body 1 and the cable inside the cylinder body 1 are connected, and the cable is the cable that supplies power to the outer rotor motor 3.

[0059] Embodiment 7:

[0060] As a more optimal implementation manner of the above embodiment, in this embodiment, a sealing ring 23 is further included. The sealing ring 23 is provided between the outer wall of the second bearing chamber 12 and the inner wall at the opening of the cylinder body 1, between the rotating shaft 4 and the end cover 2, between the piston 10 and the inner wall of the first bearing chamber 8, and between the cable adapter 22 and the bottom of the cylinder body 1. The sealing ring 23 between the rotating shaft 4 and the end cover 2 and the sealing ring 23 between the piston 10 and the inner wall of the first bearing chamber 8 are both rotary sealing rings, that is, sealing rings that can play a sealing role during rotation. The sealing ring 23 between the outer wall of the second bearing chamber 12 and the inner wall at the opening of the cylinder body 1 and the sealing ring 23 between the cable adapter 22 and the bottom of the cylinder body 1 are rubber sealing rings.

[0061] Through the above structure, the effect of sealing and waterproofing can be achieved, and water is prevented from seeping into the cylinder body 1 through the gaps between the rotating shaft 4 and the end cover 2, between the piston 10 and the inner wall of the first bearing chamber 8, between the outer wall of the second bearing chamber 12 and the inner wall of the cylinder body 1, and between the cable adapter 22 and the bottom of the cylinder body 1, thereby damaging the outer rotor motor 3. It should be noted that the sealing ring 23 is a high-pressure sealing ring, which can withstand a pressure of at least 3,500 meters of water depth.

[0062] The above is only the specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art within the technical scope recorded in the present invention can easily think of changes or substitutions, which should all be covered within the protection scope of the present invention. Therefore, the protection scope of the present invention should be subject to the protection scope of the claims.

Claims

1. An electric rotating joint of a robotic arm, characterized in that: It includes a cylinder body, an end cover, an outer-rotor motor, a rotating shaft and a rotating external connection part. The power output end of the outer-rotor motor has an external flange. A flange plate is coaxially arranged on the rotating shaft. The flange plate is connected to the external flange. The outer-rotor motor is installed on the end cover. The end cover covers the opening of the cylinder body and the outer-rotor motor is placed inside the cylinder body. One end of the rotating shaft passes through the outer-rotor motor and extends out of the bottom of the cylinder body. The other end of the rotating shaft passes through the end cover and extends out. The rotating external connection part is connected to the end of the other end of the rotating shaft. The axial pressures on both ends of the rotating shaft are the same; The two ends of the rotating shaft are respectively an A end passing through the outer-rotor motor and a B end passing through the end cover. The outer diameter of the A end is smaller than the outer diameter of the B end; A first bearing chamber is provided at the bottom of the cylinder body. The A end extends into the first bearing chamber. A first bearing is installed in the first bearing chamber. The rotating shaft is fitted and inserted into the first bearing; A suitable piston is installed in the first bearing chamber. The piston is sleeved on the A end. A baffle for preventing the piston from moving out of the first bearing chamber is also included. The baffle is installed on the end wall of the first bearing chamber. A through hole is provided on the baffle; The end face area of one end of the piston close to the baffle is the same as the end face area of the B end; When the robotic arm electric rotating joint is placed in a medium, the medium can pass through the through hole on the baffle and enter the first bearing chamber to act on the piston.

2. The electric rotating joint of a robotic arm according to claim 1, characterized in that: A second bearing chamber is provided on the end cover. A second bearing is also included. The second bearing is installed in the second bearing chamber. The second bearing chamber is inserted into the cylinder body. The outer wall of the external flange and the outer wall of the flange plate are both in interference fit with the inner ring wall of the second bearing; 3. The electric rotating joint of a robotic arm according to claim 2, wherein: The first bearing chamber extends out of the bottom of the cylinder body and the section of the first bearing chamber extending out of the cylinder body forms an installation pipe. A driven plate is rotatably installed outside the installation pipe; The rotating external connection part includes a driving plate and an external connection plate. The driving plate is vertically connected to the end of the B end. The external connection plate is connected to the driving plate. The driven plate is connected to the external connection plate.

4. The electric rotating joint of a robotic arm according to claim 3, characterized in that: A sliding bearing is also included. The sliding bearing is sleeved outside the installation pipe. The driven plate is connected to the sliding bearing.

5. A robotic arm electric rotating joint according to any one of claims 1-4, characterized in that: An external connection block is detachably and fixedly installed on the outer wall of the cylinder body.

6. The electric rotating joint of a robotic arm according to claim 5, characterized in that: An annular groove coaxial with the cylinder body is provided on the outer wall of the cylinder body. The external connection block is provided with a first arc-shaped plate adapted to the annular groove. A second arc-shaped plate is also included. The second arc-shaped plate and the first arc-shaped plate are connected together by a first screw to form a sleeve structure. The sleeve structure is sleeved in the annular groove.

7. The electric rotating joint of a robotic arm according to claim 6, characterized in that: The first arc-shaped plate is connected to the cylinder wall of the cylinder body by a second screw. The second arc-shaped plate is connected to the cylinder wall of the cylinder body by a third screw.

8. The electric rotating joint of a robotic arm according to claim 4, wherein: A cable installation hole is also provided at the bottom of the cylinder body. A cable adapter is installed at the edge of the cable installation hole. A cable electrically connected to the outer-rotor motor is also included. The cable is inserted into the cable adapter.

9. The electric rotating joint of a robotic arm according to claim 8, characterized in that: Sealing rings are provided between the outer wall of the second bearing chamber and the inner wall of the cylinder body, between the rotating shaft and the end cover, between the piston and the inner wall of the first bearing chamber, and between the cable adapter and the bottom of the cylinder body.

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