Motor assembly for downhole tools

Abstract

The application discloses a motor assembly for downhole tools, which comprises an upper part, a middle part and a lower part arranged in a downhole tool outer cylinder, the upper part comprises an upper stator, the upper stator is sequentially sleeved with a sealing shaft sleeve, an upper thrust bearing I, a lower thrust bearing, a small-diameter radial bearing, a small-diameter radial bearing retainer ring, an upper rotor and an upper turbine in a radial outward direction, the lower part comprises a lower stator, the lower stator is sequentially sleeved with a lower motor shaft locking nut, a sealing shaft sleeve, an upper thrust bearing II, a lower thrust bearing, a small-diameter radial bearing, a small-diameter radial bearing retainer ring, a lower rotor and a lower turbine in a radial outward direction, and the middle part comprises a large-diameter radial bearing and a large-diameter radial bearing retainer ring arranged in the upper part and the lower part; the application provides stable power supply and torque output, improves the heat dissipation effect, makes the motor assembly more convenient, is convenient to maintain, and is helpful for downhole tools such as measurement while drilling, vertical drilling and rotary steering to work more efficiently in deep wells.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of oil and gas drilling, and particularly relates to a motor assembly for downhole tools. BACKGROUND

[0002] With the continuous increase of drilling depth, more accurate control of the well trajectory is required. The downhole operation time of downhole tool systems such as measurement while drilling, vertical drilling and rotary steering is getting longer and longer, and more durable and stable power supply and torque output are required, so the service life and operation quality of the motor assembly for downhole tools are particularly important. The motor assembly includes a generator, a motor or a combination of the two, which can be selected according to the specific working conditions. One of the main factors affecting the service life and operation quality of the motor assembly for downhole tools is the erosion and jamming of impurities in the downhole fluid to the motor rotating system. Under the condition that the high-pressure rotary sealing technology in the downhole is not mature, how to solve the above problems is extremely urgent. SUMMARY

[0003] The purpose of the present application is to provide a motor assembly for downhole tools, which solves the problem that the service life and operation quality of the motor assembly for downhole tools need to be further improved.

[0004] The technical scheme adopted by the present application is,

[0005] The motor assembly for downhole tools comprises an upper part, a middle part and a lower part arranged in the outer cylinder of the downhole tool. The upper part comprises an upper stator, which is sequentially sleeved with a sealing shaft sleeve, an upper thrust bearing I, a lower thrust bearing, a small-diameter bearing, a small-diameter bearing retainer, an upper rotor and an upper turbine along the radial direction outward. The lower part comprises a lower stator, which is sequentially sleeved with a lower motor shaft locking nut, a sealing shaft sleeve, an upper thrust bearing II, a lower thrust bearing, a small-diameter bearing, a small-diameter bearing retainer, a lower rotor and a lower turbine along the radial direction outward. The middle part comprises a large-diameter bearing and a large-diameter bearing retainer arranged in the upper part and the lower part.

[0006] The upper turbine, the upper rotor and the lower rotor, the lower turbine, the upper motor shaft locking nut and the upper stator, and the lower motor shaft locking nut and the lower stator are connected by threads. The upper turbine and the upper thrust bearing I are connected by pin parts. The upper rotor and the lower rotor are fixed in the circumferential direction, and then axially fixed by the small-diameter bearing retainer and the large-diameter bearing retainer. The two lower thrust bearings are fixed in the circumferential direction by the upper motor shaft locking nut and the lower motor shaft locking nut. The two lower thrust bearings are limited in axial movement by the upper thrust bearing I and the upper thrust bearing II. The upper thrust bearing I and the upper thrust bearing II can rotate relative to the lower thrust bearing. The upper stator and the lower stator are tightly connected with the sealing shaft sleeve by interference. The upper stator and the lower stator are fixedly connected.

[0007] The application also has the characteristics that

[0008] The central hole of the lower thrust bearing is provided with four convex circular structures, the lower motor shaft locking nut is provided with four lower motor shaft locking nut inner concave circular groove structures, and the upper motor shaft locking nut is provided with four upper motor shaft locking nut inner concave circular groove structures.

[0009] The lower motor shaft locking nut is provided with a lower motor shaft locking nut buffer groove, and the upper motor shaft locking nut is provided with an upper motor shaft locking nut buffer groove.

[0010] The small radial bearing is provided with at least one pair of small radial bearing outer convex circular structures, and the inner hole of the small radial bearing is uniformly arranged with a plurality of small radial bearing inner turbine grooves.

[0011] The large radial bearing is provided with at least one pair of large radial bearing outer square structures, and the inner hole of the large radial bearing is uniformly arranged with a plurality of large radial bearing inner turbine grooves.

[0012] The upper rotor is provided with a concave circular groove structure and an inner square structure, wherein the number of the concave circular groove structure is not less than twice the number of the small radial bearing outer convex circular structure.

[0013] The upper thrust bearing II is uniformly provided with at least eight upper thrust bearing II chip removal grooves, and the upper thrust bearing II chip removal groove is uniformly provided with at least four upper thrust bearing II inner concave circular groove structures; the upper thrust bearing II is internally provided with an upper thrust bearing II octagonal tip central hole.

[0014] The lower rotor is provided with a lower rotor central hole inner concave circular groove structure, a lower rotor central hole inner square structure, a lower rotor central hole convex circular structure and a lower rotor octagonal tip central hole.

[0015] The upper turbine and the lower turbine can be interchanged left-handed and right-handed.

[0016] Both sides of the threaded connection are respectively provided with sealing elements.

[0017] The beneficial effects of the application are: the motor assembly for downhole tools of the application provides stable power supply and / or torque output through flexible combination of upper and lower motor functions; improves the effects of debris flushing, discharge and motor heat dissipation, reduces the debris pollution of the motor by downhole fluid, prolongs the downhole working life of the motor; makes the processing and assembly of the motor more convenient, and the post-operation maintenance more convenient, which is helpful for the more efficient operation of the downhole tools such as measurement while drilling, vertical drilling and rotary steering in deep well downhole. BRIEF DESCRIPTION OF DRAWINGS

[0018] Figure 1 It is a structural schematic diagram of the motor assembly for downhole tools of the application.

[0019] Figure 2Fig. 1 is a schematic view of the upper part of the motor assembly for downhole tools according to the present application;

[0020] Figure 3 Fig. 2 is a schematic view of the middle part of the motor assembly for downhole tools according to the present application;

[0021] Figure 4 Fig. 3 is a schematic view of the lower part of the motor assembly for downhole tools according to the present application;

[0022] Figure 5 Fig. 4 is a schematic view of the cooperation profile of the lower thrust bearing and the upper / lower motor shaft locking nut of the motor assembly for downhole tools according to the present application;

[0023] Figure 6 Fig. 5 is a schematic view of the cooperation profile of the upper / lower rotor and the small radial bearing of the motor assembly for downhole tools according to the present application;

[0024] Figure 7 Fig. 6 is a schematic view of the cooperation profile of the upper / lower rotor and the large radial bearing of the motor assembly for downhole tools according to the present application;

[0025] Figure 8 Fig. 7 is a schematic view of the cooperation profile of the upper thrust bearing II and the lower rotor of the motor assembly for downhole tools according to the present application;

[0026] Figure 9 Fig. 8 is a schematic view of the structure of the large / small radial bearing of the motor assembly for downhole tools according to the present application;

[0027] Figure 10 Fig. 9 is a schematic view of the structure of the lower thrust bearing, the upper / lower motor shaft locking nut of the motor assembly for downhole tools according to the present application;

[0028] Figure 11 Fig. 10 is a schematic view of the structure of the upper thrust bearing II of the motor assembly for downhole tools according to the present application.

[0029] In the figure, 1. upper turbine, 2. upper thrust bearing I, 3. lower thrust bearing, 4. small radial bearing retainer, 5. small radial bearing, 6. sealing sleeve, 7. upper rotor, 8. upper stator, 9. large radial bearing, 10. large radial bearing retainer, 11. lower rotor, 12. lower turbine, 13. upper thrust bearing II, 14. lower motor shaft locking nut, 15. lower stator, 16. upper motor shaft locking nut, 17. pin-like part, 18. sealing part, 19. buffer-like part, 20. circumferential fixing surface;

[0030] 301. convex circle structure, 501. small radial bearing outer convex circle structure, 502. small radial bearing inner turbine groove, 601. interference surface, 701. concave circle groove structure, 702. square inner structure, 901. large radial bearing outer square structure, 902. large radial bearing inner turbine groove, 1101. lower rotor center hole inner concave circle groove structure, 1102. lower rotor center hole inner square structure, 1103. lower rotor center hole convex circle structure, 1104. lower rotor octagonal tip center hole, 1301. upper thrust bearing II chip removal groove, 1302. upper thrust bearing II inner concave circle groove structure, 1303. upper thrust bearing II octagonal tip center hole, 1401. lower motor shaft locking nut inner concave circle groove structure, 1402. lower motor shaft locking nut buffer groove, 1601. upper motor shaft locking nut inner concave circle groove structure, 1602. upper motor shaft locking nut buffer groove. DETAILED DESCRIPTION

[0031] The motor assembly for downhole tools of the present application will be further described in detail below in conjunction with the accompanying drawings and specific embodiments.

[0032] The motor assembly for downhole tools of the present application, as shown in Figure 1 , Figure 2 , Figure 3 and Figure 4 , comprises an upper turbine 1, an upper thrust bearing I 2, a lower thrust bearing 3, a small radial bearing retainer 4, a small radial bearing 5, a sealing sleeve 6, an upper rotor 7, an upper stator 8, a large radial bearing 9, a large radial bearing retainer 10, a lower rotor 11, a lower turbine 12, an upper thrust bearing II 13, a lower motor shaft locking nut 14, a lower stator 15, an upper motor shaft locking nut 16; the entire motor assembly is installed in the outer cylinder of the downhole tool through the motor fixing device, and can rotate but cannot move axially. The upper turbine 1 and the upper rotor 7, and the lower turbine 12 and the lower rotor 11 are connected through threads. The upper turbine 1 and the upper thrust bearing I 2 are connected through a pin-like part 17. The upper rotor 7 and the lower rotor 11 are fixed circumferentially between the large radial bearing 9 and the small radial bearing 5, and then axially fixed through the small radial bearing retainer 4 and the large radial bearing retainer 10. The two lower thrust bearings 3 located at the upper and lower parts are circumferentially fixed through the convex circle-concave circle groove structure with the upper motor shaft locking nut 16 and the lower motor shaft locking nut 14, respectively, and at the same time, the two lower thrust bearings 3 are limited in axial movement by the upper thrust bearing I 2 and the upper thrust bearing II 13, respectively, and the upper thrust bearing I 2 and the upper thrust bearing II 13 can rotate relative to the lower thrust bearing 3. The upper stator 8 and the lower stator 15 are tightly connected with the sealing sleeve 6 through interference, respectively. The upper stator 8 and the lower stator 15 are connected with the upper motor shaft locking nut 16 and the lower motor shaft locking nut 14 through threads, respectively, and the upper stator 8 and the lower stator 15 are fixedly connected between them.

[0033] As shown in Figure 5 ,Figure 10 As shown, four convex circular structures 301 are arranged in the central hole of the lower thrust bearing 3, and the lower motor shaft locking nut 14 and the upper motor shaft locking nut 16 are respectively provided with four lower motor shaft locking nut inner concave circular groove structures 1401 and upper motor shaft locking nut inner concave circular groove structures 1601 matched with the convex circular structures 301. The above features can also be changed to that the lower thrust bearing 3 has four concave circular groove structures, and the lower motor shaft locking nut 14 and the upper motor shaft locking nut 16 are respectively provided with four convex structures.

[0034] As shown in Figure 2 , Figure 4 , Figure 10 As shown, the lower motor shaft locking nut 14 and the upper motor shaft locking nut 16 are respectively provided with a circle of lower motor shaft locking nut buffer grooves 1402 and upper motor shaft locking nut buffer grooves 1602 around the center. Buffering elements 19 including but not limited to rubber rings and springs can be installed in the grooves.

[0035] As shown in Figure 9 , the small-diameter bearing 5 is provided with a pair of small-diameter bearing outer convex circular structures 501 including but not limited to, and a plurality of small-diameter bearing inner turbine grooves 502 are uniformly arranged on the inner hole. The large-diameter bearing 9 is provided with a pair of large-diameter bearing outer square structures 901 including but not limited to (i.e. two symmetrical planes), and a plurality of large-diameter bearing inner turbine grooves 902 are uniformly arranged on the inner hole.

[0036] As shown in Figure 6 , Figure 7 As shown, the upper rotor 7 is provided with concave circular groove structures 701 and inner square structures 702 matched with the small-diameter bearing outer convex circular structures 501 and the large-diameter bearing outer square structures 901, wherein the number of the concave circular groove structures 701 is twice or more than the number of the convex circular structures 301.

[0037] As shown in Figure 11 , the upper thrust bearing II 13 is uniformly provided with eight upper thrust bearing II chip removal grooves 1301 including but not limited to, and the shape of the upper thrust bearing II chip removal grooves 1301 includes but is not limited to rectangular grooves, concave circular grooves, dovetail grooves, etc.; four upper thrust bearing II inner concave circular groove structures 1302 including but not limited to are uniformly arranged; and the upper thrust bearing II octagonal pointed central hole 1303 is provided, and the number of the upper thrust bearing II octagonal pointed central hole 1303 is not limited to eight.

[0038] As shown in Figure 6 , Figure 7 , Figure 8As shown, the lower rotor 11 is provided with concave groove structure 1101 matched with convex circle structure 301 and large radial bearing square structure 901, and the number of concave groove structure 1101 is twice or more than the number of convex circle structure 301; the lower rotor center hole convex circle structure 1103 corresponding to the concave groove structure 1302; the lower rotor octagonal tip center hole 1104 corresponding to the upper thrust bearing II octagonal tip center hole 1303, wherein the lower rotor octagonal tip center hole 1104 is the same shape as the upper thrust bearing II octagonal tip center hole 1303 and is completely aligned.

[0039] As shown in Figure 1 , the rotation direction of the upper turbine 1 and the lower turbine 12 can be interchanged between left-handed and right-handed.

[0040] As shown in Figure 1 , Figure 2 , Figure 3 and Figure 4 , the threaded connection between the upper turbine 1 and the upper rotor 7, the threaded connection between the lower rotor 11 and the lower turbine 12, the threaded connection between the lower motor shaft locking nut 14 and the lower stator 15, and the interference surface 601 of the sealing sleeve 6 and the upper stator 8 and the lower stator 15 are respectively provided with sealing elements 18 on both sides of the above four surfaces, so that the above three threaded connection surfaces and the interference surface 601 are in a sealed state.

[0041] The working principle of the motor assembly for the downhole tool is as follows:

[0042] As shown in Figure 1 , Figure 2 , Figure 3 and Figure 4 , the upper turbine 1, the upper thrust bearing I 2, the small diameter bearing retainer ring 4, the small diameter bearing 5, the upper rotor 7, the large diameter bearing 9, and the large diameter bearing retainer ring 10 are connected by threads, pin parts and convex circle-groove structure to form a rotating whole, which can be called an upper rotor assembly; the lower thrust bearing 3, the sealing sleeve 6, the upper stator 8 and the upper motor shaft locking nut 16 are connected by threads and convex circle-groove structure to form a rotating whole, which can be called an upper stator assembly; the upper rotor assembly and the upper stator assembly finally form an upper motor part. Figure 1 As shown, the fluid flows into the outer cylinder of the downhole tool from top to bottom at a certain speed, acts on the blades of the upper turbine 1, makes the upper turbine 1 rotate, drives the entire upper rotor assembly to rotate relative to the upper stator assembly, and the upper rotor 7 has a permanent magnet material, thereby generating electric energy for the upper motor part, realizing the supply of electric power.

[0043] Similarly, as shown in Figure 1 , Figure 2 , Figure 3 and Figure 4As shown, the lower rotor 11, the lower turbine 12, the small-diameter bearing blocking ring 4, the small-diameter bearing 5, the upper thrust bearing II 13, the large-diameter bearing 9, and the large-diameter bearing blocking ring 10 form a rotating whole, which can be called a lower rotor assembly; the lower thrust bearing 3, the sealing sleeve 6, the lower motor shaft locking nut 14, and the lower stator 15 form a rotating whole, which can be called a lower stator assembly; and the lower rotor assembly and the lower stator assembly finally form a lower motor part. The function of the lower motor part can have two settings. When set as a generator, the blade rotation direction of the lower turbine 12 is the same as that of the upper turbine 1, and the principle of the upper motor part is the same, forming a double motor power supply to meet the long-time operation requirement of downhole tools such as logging while drilling; when set as a torque motor, the fluid flows into the outer cylinder of the downhole tool from top to bottom at a certain speed, because the lower stator 15 and the upper stator 8 are fixedly connected and have the same direction, while the blade rotation direction of the lower turbine 12 is opposite to that of the upper turbine 1. At this time, the upper motor part supplies direct current to the lower stator 15, so that the lower rotor assembly driven to rotate by the lower turbine 12 generates a reverse torque to the lower stator assembly, thereby controlling the torque and rotating action output of the lower stator part to perform vertical drilling, rotary steering, and other downhole operations as required. According to the working condition, the function of the torque motor can also be set in the upper motor part, and the function of the generator can be set in the lower motor part. The rotation directions of the upper turbine 1 and the lower turbine 12 can be interchangeable.

[0044] As shown in Figures 5-11 , the lower thrust bearing 3, the small-diameter bearing 5, the upper rotor 7, the large-diameter bearing 9, the lower rotor 11, the upper thrust bearing II 13, the lower motor shaft locking nut 14, and the upper motor shaft locking nut 16 are respectively provided with corresponding convex circular structures and concave circular groove structures: the convex circular structure 301, the small-diameter bearing outer convex circular structure 501, the concave circular groove structure 701, the lower rotor center hole inner concave circular groove structure 1101, the lower rotor center hole convex circular structure 1103, the upper thrust bearing II inner concave circular groove structure 1302, the lower motor shaft locking nut inner concave circular groove structure 1401, the upper motor shaft locking nut inner concave circular groove structure 1601, the square structure 702, the large-diameter bearing outer square structure 901, and the lower rotor center hole inner square structure 1102. The circumferential fixation of the rotating parts can be more simply realized, and the machining and assembly are relatively convenient. However, the traditional design usually adopts threads or circumferentially arranged locking screws for clamping to realize the fixation, and the machining and assembly are relatively cumbersome, and the threads are prone to loosening, causing the falling of parts.

[0045] As shown in Figure 2 , Figure 4 , Figure 10As shown, the lower motor shaft locking nut 14 and the upper motor shaft locking nut 16 are respectively provided with a circle of lower motor shaft locking nut buffer grooves 1402 and upper motor shaft locking nut buffer grooves 1602 around the center. Buffer elements 19 such as but not limited to rubber rings and springs can be installed in the grooves. When the fluid flow rate in the outer cylinder of the downhole tool is unstable, the buffer elements can respectively reduce the axial impact between the lower thrust bearing 3 and the lower motor shaft locking nut 14 and the upper motor shaft locking nut 16, thereby prolonging the service life of the motor assembly during downhole operation.

[0046] As shown in Figure 9 , the inner holes of the small radial bearing 5 and the large radial bearing 9 are provided with a plurality of uniformly arranged small radial bearing inner turbine grooves 502 and large radial bearing inner turbine grooves 902. Due to the current technical difficulties in high pressure, high temperature and long time operation, the bearing gap between the small radial bearing 5 and the large radial bearing 9 and the sealing sleeve 6 cannot be sealed. During operation of the motor assembly, the fluid in the outer cylinder of the downhole tool carries debris that can enter the annulus between the rotor and the stator through the bearing gap. If the debris is not treated in time, the final debris deposition will cause the motor assembly to fail to work, so when the small and large radial bearings rotate, the inner turbine grooves in their inner holes can generate strong rotational flow, which can enhance the self-flushing effect of the fluid, thereby minimizing debris deposition, and also has a good effect on heat dissipation of the stator and the rotor.

[0047] As shown in Figure 6 , Figure 8 , and Figure 11 , the number of concave circular groove structures 701 of the upper rotor 7 and the lower rotor 11 and the concave circular groove structure 1101 in the center hole of the lower rotor is twice or more than the number of convex circular structures 501, so there are one or more concave grooves in the vacant position. The lower rotor center hole convex circular structure 1303 and the lower rotor octagonal tip center hole 1104 provided on the lower rotor 11 and the upper thrust bearing II 13 are uniformly provided with a plurality of chip removal grooves 1301 including but not limited to eight. The above structures provide sufficient debris removal channels and auxiliary rotational flow effect to enhance the debris cleaning effect.

[0048] As shown in Figure 1 , Figure 2 , Figure 3 , and Figure 4As shown, the threaded connection of the upper turbine 1 and the upper rotor 7, the threaded connection of the lower rotor 11 and the lower turbine 12, the threaded connection of the lower motor shaft locking nut 14 and the lower stator 15, the interference surface 601, the two sides of the above four surfaces are respectively provided with sealing elements 18, so that the above three threaded connection surfaces and the interference surface are in a sealed state, and the downhole contaminated fluid cannot enter. In this way, the problem that the downhole tool cannot be disassembled for maintenance after long-term operation in a harsh downhole environment due to corrosion of the above surfaces caused by fluid corrosion is avoided, the use of corrosion-resistant materials for related parts is reduced, and the cost of the motor is reduced.

[0049] The motor assembly for the downhole tool provides stable power supply and torque output through flexible combination of the upper and lower motor functions, improves the effects of debris flushing, discharge and motor heat dissipation, prolongs the service life of the motor in the downhole, makes the processing and assembly of the motor more convenient, and facilitates the operation of the downhole tool such as the measurement while drilling, the vertical drilling and the rotary steering in the deep well.

Claims

1. A motor assembly for use in a downhole tool, characterized by The application relates to a downhole tool, which comprises an upper part, a middle part and a lower part arranged in the outer cylinder of the downhole tool, the upper part comprises an upper stator (8), the upper stator (8) is sequentially sleeved with a sealing sleeve (6), an upper thrust bearing I (2), a lower thrust bearing (3), a small radial bearing (5), a small radial bearing retainer (4), an upper rotor (7) and an upper turbine (1) in a radial direction, the lower part comprises a lower stator (15), the lower stator (15) is sequentially sleeved with a lower motor shaft locking nut (14), the sealing sleeve (6), the upper thrust bearing II (13), the lower thrust bearing (3), the small radial bearing (5), the small radial bearing retainer (4), a lower rotor (11) and a lower turbine (12) in a radial direction, and the middle part comprises a large radial bearing (9) and a large radial bearing retainer (10) arranged in the upper part and the lower part. The upper turbine (1) is connected with the upper rotor (7), the lower rotor (11) is connected with the lower turbine (12), the upper motor shaft locking nut (16) is connected with the upper stator (8), the lower motor shaft locking nut (14) is connected with the lower stator (15), the upper turbine (1) is connected with the upper thrust bearing I (2) through a pin-like part (17), the upper rotor (7) and the lower rotor (11) are fixed in a circumferential direction, and then are axially fixed through the small radial bearing retainer (4) and the large radial bearing retainer (10), the two lower thrust bearings (3) are fixed in a circumferential direction through the upper motor shaft locking nut (16) and the lower motor shaft locking nut (14) respectively, the two lower thrust bearings (3) are axially limited by the upper thrust bearing I (2) and the upper thrust bearing II (13) respectively, the upper thrust bearing I (2) and the upper thrust bearing II (13) can rotate relative to the lower thrust bearing (3), the upper stator (8) and the lower stator (15) are tightly connected with the sealing sleeve (6) through interference, and the upper stator (8) and the lower stator (15) are fixedly connected.

2. The motor assembly for a downhole tool of claim 1, wherein, The central hole of the lower thrust bearing (3) is provided with four convex circular structures (301), the lower motor shaft locking nut (14) is provided with four lower motor shaft locking nut inner recessed groove structures (1401), and the upper motor shaft locking nut (16) is provided with four upper motor shaft locking nut inner recessed groove structures (1601).

3. The motor assembly for a downhole tool of claim 1, wherein, The lower motor shaft locking nut (14) is provided with a lower motor shaft locking nut buffer groove (1402), and the upper motor shaft locking nut (16) is provided with an upper motor shaft locking nut buffer groove (1602).

4. The motor assembly for a downhole tool of claim 1, wherein, The small radial bearing (5) is provided with at least one pair of small radial bearing outer convex circular structures (501), and the inner hole of the small radial bearing (5) is uniformly arranged with a plurality of small radial bearing inner turbine grooves (502).

5. The motor assembly for a downhole tool of claim 1, wherein, The large radial bearing (9) is provided with at least one pair of large radial bearing outer square structures (901), and the inner hole of the large radial bearing (9) is uniformly arranged with a plurality of large radial bearing inner turbine grooves (902).

6. The motor assembly for a downhole tool of claim 4, wherein, The upper rotor (7) is provided with concave circular groove structure (701), inner square structure (702), wherein the number of the concave circular groove structure (701) is not less than twice the number of the small diameter bearing outer convex circular structure (501).

7. The motor assembly for a downhole tool of claim 1, wherein, The upper thrust bearing II (13) is uniformly provided with at least eight upper thrust bearing II chip removal grooves (1301), and the upper thrust bearing II chip removal grooves (1301) are uniformly provided with at least four upper thrust bearing II inner concave circular groove structures (1302); the upper thrust bearing II (13) is internally provided with an upper thrust bearing II octagonal tip center hole (1303).

8. The motor assembly for a downhole tool of claim 1, wherein, The lower rotor (11) is provided with a lower rotor center hole inner concave circular groove structure (1101), a lower rotor center hole inner square structure (1102), a lower rotor center hole convex circular structure (1103) and a lower rotor octagonal tip center hole (1104).

9. The motor assembly for a downhole tool of claim 1, wherein, The upper turbine (1) and the lower turbine (12) can be interchanged left-handed and right-handed.

10. The motor assembly for a downhole tool of claim 1, wherein, Both sides of the threaded connection are respectively provided with sealing elements (18).

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