Electric precise rotating nipple

Abstract

The invention provides an electric precise rotating nipple which comprises an upper connector and a lower connector which are provided with a first oil way channel and a first cable channel, and a driving part connected between the upper connector and the lower connector, and the driving part comprises a fixing sleeve and a driving rotating device installed in the fixing sleeve. The rotating shaft is connected with the driving rotating device, one end of the rotating shaft extends out of the fixing sleeve, the outer surface corresponding to the rotating shaft is movably sleeved with a rotating sleeve, one end of the rotating sleeve is movably connected with the fixing sleeve, the other end of the rotating sleeve is fixedly connected with the lower connector, and a guide sleeve is installed at the end of the rotating shaft and connected with the rotating sleeve and the rotating shaft in a clamped mode at the same time. When rotating, the rotating shaft drives the rotating sleeve and the lower connector to rotate synchronously through the guide sleeve. The device is short and small in structure, the upper connector and the lower connector can serve as a middle connecting short section of any measuring equipment, angle adjustment is conducted on the connected measuring equipment, or the device is connected to the same measuring equipment, and relative rotation of the short sections of the measuring equipment is achieved.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of oil exploration, in particular to an electric precision rotating nipple capable of adjusting the working angle of downhole measuring equipment. BACKGROUND

[0002] In the field of oil, the geological conditions of the downhole need to be understood for a newly drilled well, therefore, a drill pipe or a cable is often used to connect corresponding measuring equipment to the downhole to collect or analyze information of the liquid and the formation in the downhole.

[0003] Taking sampling as an example, there is a drill bit sampling device at present, which collects the material in the formation through a drill bit installed on the nipple and perpendicular to the well wall, and then collects the material into a sampling barrel. However, the current sampling structure can only install one drill bit, and therefore can only sample in the direction of the drill bit. Since the underground conditions are complex, it cannot be determined whether the sample in the current direction meets the detection requirements. If more samples in the same position are needed for comprehensive analysis, the well must be lowered repeatedly for sampling, which is low in efficiency.

[0004] In addition, a large amount of mud exists in the downhole, and the measuring equipment connected by the cable to the downhole may be adhered to the well wall due to contact with the well wall, which affects the speed of lowering into the well, and even is stuck in the non-designated position. SUMMARY

[0005] The present application aims to provide an electric precision rotating nipple capable of adjusting the working angle of downhole measuring equipment.

[0006] Specifically, the present application provides an electric precision rotating nipple, which comprises an upper joint and a lower joint with a first oil passage and a first cable passage, and a driving part connected between the upper joint and the lower joint. The driving part comprises a fixed sleeve, a driving rotating device installed in the fixed sleeve, a rotating shaft connected with the driving rotating device and having one end extending out of the fixed sleeve, a rotating sleeve movably sleeved on the outer surface corresponding to the rotating shaft, one end of the rotating sleeve movably connected with the fixed sleeve, and the other end fixedly connected with the lower joint, a guide sleeve installed at the end of the rotating shaft, the guide sleeve being simultaneously connected with the rotating sleeve and the rotating shaft, and the rotating shaft driving the rotating sleeve and the lower joint to rotate synchronously through the guide sleeve when the rotating shaft rotates.

[0007] In one embodiment, the driving rotating device comprises a motor fixedly installed in the fixed sleeve and a speed reducer driven by the motor, and the output end of the speed reducer is connected with the rotating shaft.

[0008] In one embodiment, the end of the rotating shaft extending out of the fixed sleeve is provided with a radially protruding clamping block, the inside of the guide sleeve is provided with a limiting slot for inserting the clamping block, the inner surface of the rotating sleeve is provided with an axial sliding slot, the inside of the guide sleeve is provided with a limiting slot for inserting the clamping block, and the outer surface is provided with a clamping rail which is inserted into the sliding slot of the rotating sleeve.

[0009] In one embodiment, the side wall of the fixed sleeve is provided with a second oil passage and a second cable passage in the axial direction, the side wall of the guide sleeve is provided with a third oil passage and a third cable passage which pass through in the axial direction, and the end of the third cable passage close to the lower connector is provided with a cable extension pipe which is inserted into the lower connector, and a multi-core plug or a multi-core socket is inserted into the opening of the cable extension pipe.

[0010] In one embodiment, the end of the fixed sleeve close to the guide sleeve is provided with an axially protruding cable bundling column which is used for bundling the cables led out of the second cable passage.

[0011] In one embodiment, the upper connector and the lower connector each comprise a transfer connector, and a plug-in seat is installed in the inside of the transfer connector, the first oil passage and the first cable passage are arranged on the plug-in seat, the first oil passage and the first cable passage are communicated with the second oil passage and the second cable passage on the fixed sleeve through a sealing connector, a circuit board cavity is arranged in the plug-in seat of the upper connector, and a circuit board for controlling the operation of the motor is installed in the circuit board cavity.

[0012] In one embodiment, the reducer is sleeved with a limiting sliding sleeve at the connection position with the rotating shaft, the side wall of the limiting sliding sleeve is provided with a protruding first limiting block on the inner surface, and a protruding second limiting block is arranged on the outer surface at the corresponding position, an inner groove is arranged at the corresponding position of the rotating shaft and the limiting sliding sleeve, the inner diameter of the limiting sliding sleeve is larger than the diameter of the rotating shaft, an angle limiting block is inserted into the inner groove, the inserted angle limiting block protrudes out of the inner groove and contacts with the inner surface of the limiting sliding sleeve, and a corresponding annular groove is arranged at the corresponding position of the fixed sleeve and the limiting sliding sleeve.

[0013] In one embodiment, a reducer fixing seat is installed between the reducer and the fixed sleeve, a motor fixing seat is installed at the end of the motor close to the upper connector, corresponding axial channels are arranged on the reducer fixing seat and the motor fixing seat, positioning sealing pipes are inserted at both ends of the channels, the reducer fixing seat and the motor fixing seat are directly connected through the positioning sealing pipes, the channel on the reducer fixing seat protrudes out of the outer surface of the reducer fixing seat, an inner clamping groove with the same shape is arranged at the corresponding position of the inner surface of the fixed sleeve, and the reducer fixing seat is inserted into the fixed sleeve and fixed by the channel and the inner clamping groove.

[0014] In one embodiment, bearings are installed between the rotating sleeve and the fixed sleeve, the outer surface of the fixed sleeve is provided with a first step and a second step, the inner surface of the rotating sleeve is provided with a third step, one end of the installed bearings is blocked by the second step, the other end is blocked by the third step, a first positioning ring is installed at the first step and is screwed with the inner surface of the rotating sleeve, a second positioning ring is installed at the third step and is screwed with the fixed sleeve, and the number of bearings is four.

[0015] In one embodiment, the driving rotating device comprises a swing cylinder connected with the rotating shaft, and a forward rotation oil path and a reverse rotation oil path connected with the swing cylinder are arranged on the first oil path channel.

[0016] The electric precise rotating short section has a short structure, can be connected with any measuring device through the upper joint and the lower joint, is internally provided with independent oil paths and cable channels, can supply oil paths and cables for itself, can provide oil path and cable connection for adjacent measuring devices, and does not affect any work of the measuring device. In addition, the device can be directly connected on the same measuring device, so that relative rotation of each short section of one measuring device is realized.

[0017] When the electric precise rotating short section is used for a drill bit sampling device, the drill bit can perform annular sampling at the same position, the sampling effect is improved, when other measuring devices are used, if the current measuring position effect is not up to standard, the position can be adjusted through the short section. In addition, the length of the existing measuring device can reach dozens of meters, when the measuring device is lowered into the well, the measuring device is in contact with the well wall, so that adhesion between the measuring device and the mud between the well wall is generated, the measuring device is not conducive to being lowered into or pulled out of the well, the short section can be rotated to separate part of the pipe body from the well wall, the adhesion is reduced, and the short section can prevent stagnation, and is particularly suitable for measuring devices lowered into the well by using a cable. Further, the short section takes the driving part as a reference, the upper joint and the lower joint are relatively rotatable, when the rotating shaft rotates without the lower joint, the measuring device connected with the upper joint can also rotate, that is, when the upper joint is stationary, the lower joint can rotate, when the lower joint is stationary, the upper joint can also rotate, and the working efficiency of the whole electric precise rotating short section is greatly improved. BRIEF DESCRIPTION OF DRAWINGS

[0018] Figure 1 is a structural schematic view of the electric precise rotating short section of the present application; Figure 2 is an A-A sectional view of Figure 1 ; Figure 3 is a B-B sectional view of Figure 1 ; Figure 4 is a schematic view of a rotating angle of the rotating shaft and the limiting sliding sleeve in Figure 3 ; Figure 5is another schematic view of the electric precision rotary short section structure of the present application; Figure 6 is Figure 4 a C-C sectional view of the present application; Figure 7 is a schematic view of the structure of the swing cylinder in one embodiment of the present application. DETAILED DESCRIPTION

[0019] The structure and working process of the present application will be further described through specific embodiments and drawings. In the following embodiments, the orientation of the drawings is described when facing the screen. In the following embodiments, only the present application is described.

[0020] As Figure 1 shown, the present embodiment discloses an electric precision rotary short section, which comprises an upper connector 1 and a lower connector 3 with a first oil passage 14 and a first cable passage 15, and a driving part 2 connected between the upper connector 1 and the lower connector 3 to allow the upper connector 1 to rotate radially relative to the lower connector 3.

[0021] The internal structures of the upper connector 1 and the lower connector 3 are basically the same, but the upper connector 1 represents a plug structure, while the lower connector 3 represents a socket structure, i.e. the upper connector 1 can be directly inserted into the lower connector 3 of the connected measuring equipment, forming a sealed connection while realizing the internal connection of the oil passage and the cable, while the lower connector 3 can directly insert the upper connector 1 of the connected measuring equipment, and internally form the direct connection of the oil passage and the cable. The internal structure and installation method of both will be described below taking the structure of the upper connector 1 as an example, and the difference will be described separately.

[0022] The upper connector 1 comprises a first transfer connector 11 and a plug-in seat 12 inside the first transfer connector 11, the first transfer connector 11 is fixedly connected with the driving part 2 through a clamp 13, the fixed plug-in seat 12 of the first transfer connector 11 forms a plug-in with the driving part 2, a plurality of independent passages are provided in the plug-in seat 12, including a first oil passage 14 and a first cable passage 15, the number of the first oil passage 14 can be set as needed, such as for conveying high-pressure hydraulic oil, low-oil hydraulic and liquid sample, etc., a sealing universal pipeline connector head 141 is inserted and assembled at the mouth of the first oil passage 14, and a multi-core plug or a multi-core socket 151 is sealingly installed at both ends of the mouth of the first cable passage 15.

[0023] The specific driving part 2 comprises a hollow fixed sleeve 21, the entire fixed sleeve 21 is taperedly reduced from one end to the other end, as Figure 1 shown, the left end is a driving section 211 threadedly connected with the first transfer connector 11, and the right end is a rotating section 212, which is gradually reduced from the driving section 211 to the rotating section 212.

[0024] The driving rotating device in the embodiment can be selected as required, such as a motor and a reducer cooperation driving, a motor and a screw structure cooperation driving, and a swing cylinder driving, and the following is described by taking the structure of the motor cooperating with the reducer.

[0025] The motor 22 and the reducer 23 driven by the motor 22 are fixedly installed in the driving section 211, the reducer 23 is connected with the rotating shaft 24, the rotating shaft 24 is located in the rotating section 211 of the fixed sleeve 21, and an end of the rotating shaft 24 away from the reducer 23 extends out of the rotating section 212, the rotating sleeve 25 is movably sleeved on the outer surface of the rotating section 212 of the fixed sleeve 21, one end of the rotating sleeve 25 is movably connected with the fixed sleeve 21, and the other end is threadedly connected with the second intermediate joint 31 of the lower joint 3, and the guide sleeve 26 is installed on the end of the rotating shaft 23, the guide sleeve 26 is simultaneously clamped with the rotating sleeve 25 and the rotating shaft 23, so that the rotating shaft 23 drives the rotating sleeve 25 to synchronously rotate through the guide sleeve 26 when rotating.

[0026] In work, the electric precise rotating short section is connected with adjacent measuring devices through the upper joint 1 and the lower joint 3, and at this time, the oil passage and the cable can be communicated between adjacent short sections. When rotation is required, the motor 22 is controlled to rotate, thereby driving the reducer 23 and the rotating shaft 24 to rotate, the guide sleeve 25 clamped with the rotating shaft 24 is synchronously rotated and drives the rotating sleeve 26 to rotate, thereby driving the connected lower joint 3 to rotate, so that the measuring device connected with the lower joint 3 is radially rotated, so that the angle of sampling of the measuring device can be adjusted, for example, the currently connected drill bit sampling short section is oriented at 0 degree, and under the driving of the lower joint 3, the drill bit sampling short section can be rotated in the range of 360 degrees, so that annular sampling can be performed at the same position of the well wall, a plurality of samples are taken at different angles at the same position, and then comprehensive analysis is performed on the samples, so that the sample analysis precision at the position can be improved.

[0027] The electric precise rotating short section in the embodiment has a short structure since only the motor 22 and the reducer 23 are installed, can be connected with any measuring device through the upper joint 1 and the lower joint 3, is internally provided with independent oil passage and cable passage, can supply oil passage and cable for itself, and can provide oil passage and cable connection for adjacent measuring devices, and does not affect any work of the measuring device. In addition, the device can be directly connected on the same measuring device, so that relative rotation of short sections of the measuring device is realized.

[0028] When used in drill bit sampling equipment, this embodiment allows the drill bit to perform circumferential sampling at the same location, improving sampling efficiency. When using other measuring equipment, if the current measurement position is not satisfactory, the position can also be adjusted using this short section. Furthermore, existing measuring equipment can be over ten meters long, and when lowered into the well, it comes into contact with the well wall, causing adhesion to the mud, which is detrimental to both lowering and raising the equipment. This embodiment can rotate the tube to detach part of the tube from the well wall, reducing adhesion and preventing stagnation. It is particularly suitable for measuring equipment lowered into the well using cables.

[0029] Furthermore, in this embodiment, the upper connector 1 and the lower connector 3 rotate relative to each other, with the drive unit 2 as the reference. When the rotating shaft 24 cannot drive the lower connector 3 to rotate, the measuring device connected to the upper connector 1 can also rotate. That is, when the upper connector 1 is stationary, the lower connector 3 can rotate, and when the lower connector 3 is stationary, the upper connector 1 can also rotate, which greatly improves the working efficiency of the entire electric precision rotating section.

[0030] like Figure 2 As shown, in one embodiment, the engaging structure of the guide sleeve 26 is as follows: a radially protruding locking block 241 is provided at one end of the rotating shaft 24 extending out of the rotating section 212; an axial sliding groove 251 is provided on the inner surface of the rotating sleeve 25; a limiting groove 261 is provided inside the guide sleeve 26 for the locking block 241 of the rotating shaft 24 to be inserted; and a locking rail 262 is provided on the outer surface to interlock with the sliding groove 251 on the rotating sleeve 25. When the guide sleeve 26 is fitted onto the rotating shaft 24, the locking block 241 on the rotating shaft 24 enters along the inner limiting groove 261, while the locking rail 262 on the outer surface enters the sliding groove 251 on the inner surface of the rotating sleeve 25. When the rotating shaft 24 rotates, the locking block 241 drives the guide sleeve 26 to rotate synchronously, and the rotation of the guide sleeve 26 drives the rotation of the rotating sleeve 25, thereby driving the lower connector 3 and the measuring device connected to the lower connector 3 to rotate simultaneously.

[0031] A second oil passage 213 and a second cable passage 214 are axially arranged on the side wall of the fixed sleeve 21. A third oil passage 263 and a third cable passage 264 are axially connected inside the side wall of the guide sleeve 26. A cable extension tube 265 is provided at one end of the third cable passage 264 near the lower connector 3, which can be inserted into the lower connector 3. A multi-core plug or a multi-core socket can be inserted into the opening of the cable extension tube 265. In this embodiment, the internal oil passage and cable can be connected by the oil passage and cable passage in the upper connector 1, the drive part 2, and the lower connector 3.

[0032] like Figure 3As shown, in one embodiment, in order to accurately position the angle of rotation, a limiting sleeve 27 is sleeved at the connection between the reducer 23 and the rotating shaft 24. A first limiting block 271 is protruded on the inner surface of the side wall of the limiting sleeve 27, and a second limiting block 272 is protruded on the corresponding position of the outer surface of the side wall. An inner recess 242 is arranged at the corresponding position of the rotating shaft 24 and the limiting sleeve 27. The inner diameter of the limiting sleeve 27 is larger than the diameter of the rotating shaft 24. An angle limiting block 243 is inserted into the inner recess 242. After being inserted, the angle limiting block 243 protrudes out of the inner recess 242 and is in contact with the inner surface of the limiting sleeve 27. A corresponding annular groove 215 is arranged at the corresponding position of the fixed sleeve 21 and the limiting sleeve 27. The limiting sleeve 27 installed in the annular groove 242 is positioned and cannot rotate radially by the second limiting block 272.

[0033] In operation, since the inner diameter of the limiting sleeve 27 is larger than the diameter of the rotating shaft 24, the angle limiting block 243 can rotate with the surface of the rotating shaft 24. When the rotating shaft 24 drives the angle limiting block 243 in the inner recess 242 to rotate, the rotation of the angle limiting block 243 to the right will be blocked by the first limiting block 271. At this time, the rotating shaft 24 remains stationary, that is, the lower joint 3 does not rotate while the fixed sleeve 21 rotates and drives the upper joint 1 to rotate. Figure 4 As shown, the state diagrams of the rotation of the angle limiting block 243 at 90°, 180°, 270° and 360° are shown. When the rotating shaft rotates, the lower joint 3 will rotate synchronously and finally be blocked by the first limiting block 271.

[0034] As shown, Figure 5 In one embodiment, a reducer fixing seat 231 is installed between the reducer 23 and the driving section 211. A motor mounting seat 221 is installed at the end of the motor 22 close to the upper joint 1. Corresponding axial channels are arranged on the reducer fixing seat 231 and the motor mounting seat 221. The channels are used to connect the first oil passage and the second oil passage, and the first cable passage and the second cable passage. Positioning sealing tubes 232 are inserted at both ends of the channels. The adjacent channels of the reducer fixing seat 231 and the motor mounting seat 221 are directly connected through the positioning sealing tubes 232. The motor 22 and the reducer 23 can be directly fixed together through the positioning sealing tubes 232 to prevent radial rotation between them. Further, the motor 22 is directly fixed with the reducer fixing seat 231 through bolts.

[0035] As shown, Figure 6As shown, in order to improve the fixing effect with the fixing sleeve 21, the channel on the reducer fixing seat 231 protrudes from the outer surface of the reducer fixing seat 231, forming multiple protruding ridges 233. At the same time, corresponding inner slots 215 are provided at corresponding positions on the inner surface of the drive section 211. The reducer fixing seat 231 is inserted into the drive section 211 and fixed by the protruding ridges 233 and the inner slots 215.

[0036] like Figure 1 As shown, in one embodiment, a bearing 28 that facilitates radial rotation is installed between the rotating sleeve 25 and the rotating section 212. To stabilize the bearing 28, a first step 216 and a second step 217 are provided on the outer surface of the rotating section 212 of the fixed sleeve 21. After installation, one end (left end) of the bearing 28 is blocked by the second step 217. A first positioning ring 281, threadedly connected to the inner surface of the rotating sleeve 25, is installed at the first step 216. A third step 252, blocking the other end (right end) of the bearing 28, is provided on the inner surface of the rotating sleeve 25. A second positioning ring 282, threadedly connected to the rotating section 212 of the fixed sleeve 21, is installed at the third step 252. The bearing 28 is used to improve the rotational effect between the rotating sleeve 25 and the fixed sleeve 21. The second step 217 and the third step 252 can fix the bearing 28, while the first positioning ring 281 and the second positioning ring 284 can adjust the installation space of the bearing 28. The specific number of bearings 28 is installed as needed; in this embodiment, four bearings 28 are installed.

[0037] In one embodiment, to prevent the cable extending from the fixed sleeve 21 from getting caught in the rotating shaft 24, an axially protruding cable bundling post 218 is provided at one end of the rotating section 212 of the fixed sleeve 21 near the guide sleeve 26. The cable leading out from the second cable channel 214 in the rotating section 212 is tied to the cable bundling post 218 and then introduced into the cable extension tube 265 of the guide sleeve 26 to connect with the multi-core plug.

[0038] In one embodiment, to facilitate the control of the motor 21, a circuit cavity is provided in the plug socket 12 of the upper connector 1, and a circuit board 16 is installed in the circuit cavity. The cable led out from the multi-core plug of the upper connector 1 is directly connected to the circuit board 16, and then connected to the motor 21 through the circuit board 16 to achieve individual control.

[0039] Hydraulic oil is filled into each cavity of the precision rotating section of the motor to prevent compression by downhole pressure.

[0040] like Figure 7As shown, the driving rotating device 2 adopts a swing cylinder 4 instead, and other structures are the same as those of the motor matching reducer, which will not be repeated here. The difference between the swing cylinder 4 and the motor matching reducer is that the swing cylinder 4 is directly installed on the rotating shaft 24, so that the swing motion of the swing cylinder 4 is converted into the rotating motion of the rotating shaft 24. At the same time, the direct rotation oil path 41 and the reverse rotation oil path 42 directly communicated with the swing cylinder 4 are installed on the first oil path channel 14 or the second oil path channel 213, and the direct rotation oil path 41 and the reverse rotation oil path 42 respectively input high-pressure hydraulic oil into the swing cylinder 4 to drive the swing cylinder 4 to rotate forward or reverse, thereby driving the rotating shaft 24 to rotate forward or reverse.

[0041] At this point, those skilled in the art should recognize that although the present application has been shown and described in detail in the above embodiments, many other variations or modifications can be directly determined or deduced according to the disclosure of the present application without departing from the spirit and scope of the present application, which conform to the principles of the present application. Therefore, the scope of the present application should be understood and recognized as covering all these other variations or modifications.

Claims

1. An electrically operated precision rotary joint, comprising an upper connector and a lower connector having a first oil passage and a first cable passage, and a drive unit connected between the upper connector and the lower connector, characterized in that, The drive unit includes a fixed sleeve, a drive rotation device installed inside the fixed sleeve, a rotating shaft connected to the drive rotation device and extending one end out of the fixed sleeve, a rotating sleeve movably fitted on the outer surface corresponding to the rotating shaft, one end of the rotating sleeve being movably connected to the fixed sleeve, and the other end being fixedly connected to the lower connector, a guide sleeve being installed at the end of the rotating shaft, the guide sleeve being engaged with both the rotating sleeve and the rotating shaft, and the rotating shaft driving the rotating sleeve and the lower connector to rotate synchronously through the guide sleeve when rotating.

2. The electric precision rotary sub-joint according to claim 1, characterized in that, The drive rotation device includes a motor fixedly installed in a fixed sleeve and a reducer driven by the motor, with the output end of the reducer connected to the rotation shaft.

3. The electric precision rotary sub-joint according to claim 1, characterized in that, The end of the rotating shaft extending out of the fixed sleeve is provided with a radially protruding locking block. The inside of the guide sleeve is provided with a limiting groove for the locking block to be inserted. The inner surface of the rotating sleeve is provided with an axial sliding groove. The inside of the guide sleeve is provided with a limiting groove for the locking block to be inserted. The outer surface is provided with a locking rail that interlocks with the sliding groove on the rotating sleeve.

4. The electric precision rotary sub-joint according to claim 1, characterized in that, The side wall of the fixed sleeve is provided with a second oil passage and a second cable passage along the axial direction. The side wall of the guide sleeve is provided with a third oil passage and a third cable passage that pass through the axial direction. The end of the third cable passage near the lower connector is provided with a cable extension tube that is inserted into the lower connector. A multi-core plug or multi-core socket is inserted into the opening of the cable extension tube.

5. The electrically operated precision rotary sub-joint according to claim 4, characterized in that, The fixing sleeve is provided with an axially protruding cable bundling post at one end near the guide sleeve. The cable bundling post is used to bundle the cable led out from the second cable channel.

6. The electrically operated precision rotary sub-joint according to claim 4, characterized in that, The upper connector and the lower connector each include a transfer connector and a plug socket installed inside the transfer connector. The first oil passage and the first cable passage are arranged on the plug socket. The first oil passage and the first cable passage are connected to the second oil passage and the second cable passage on the fixed sleeve through a sealing connector. A circuit board cavity is provided in the plug socket of the upper connector, and a circuit board for controlling the operation of the motor is installed in the circuit board cavity.

7. The electrically operated precision rotary sub-joint according to claim 2, characterized in that, A limiting sleeve is fitted at the connection between the reducer and the rotating shaft. A first limiting block is provided on the inner surface of the side wall of the limiting sleeve, and a second limiting block is provided on the corresponding position on the outer surface of the side wall. An inner groove is provided at the position corresponding to the rotating shaft and the limiting sleeve. The inner diameter of the limiting sleeve is larger than the diameter of the rotating shaft. An angle limiting block is inserted into the inner groove. After insertion, the angle limiting block extends out of the inner groove and contacts the inner surface of the limiting sleeve. An annular groove of a corresponding shape is provided at the position corresponding to the fixed sleeve and the limiting sleeve.

8. The electrically operated precision rotary sub-joint according to claim 2, characterized in that, A reducer mounting base is installed between the reducer and the fixed sleeve. A motor mounting base is installed at the end of the motor near the upper connector. Corresponding axial channels are provided on the reducer mounting base and the motor mounting base. Positioning sealing tubes are inserted at both ends of the channels. The reducer mounting base and the motor mounting base are directly connected through the positioning sealing tubes. The channel on the reducer mounting base protrudes from the outer surface of the reducer mounting base. A corresponding inner groove of the same shape is provided on the inner surface of the fixed sleeve. The reducer mounting base is inserted into the fixed sleeve and fixed by the channel and the inner groove.

9. The electrically operated precision rotary sub-joint according to claim 1, characterized in that, A bearing is installed between the rotating sleeve and the fixed sleeve. The outer surface of the fixed sleeve is provided with a first step and a second step, and the inner surface of the rotating sleeve is provided with a third step. After installation, one end of the bearing is blocked by the second step and the other end is blocked by the third step. A first positioning ring that is threaded to the inner surface of the rotating sleeve is installed at the first step, and a second positioning ring that is threaded to the fixed sleeve is installed at the third step. The number of bearings is four.

10. The electrically operated precision rotary sub-joint according to claim 1, characterized in that, The drive rotation device includes a swing cylinder connected to the rotation shaft, and a forward rotation oil circuit and a reverse rotation oil circuit connected to the swing cylinder are provided on the first oil circuit channel.

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