Screw drill transmission shaft assembly using hydrodynamic thrust bearing group and hydrodynamic seal

Abstract

The present invention discloses a screw drill transmission shaft assembly that uses a liquid dynamic pressure thrust bearing group and a liquid dynamic pressure seal. It is mainly composed of a transmission shaft, a lower seal assembly, a lower sleeve, a lower housing, a lower TC assembly, a liquid dynamic pressure thrust bearing group assembly, an upper housing, an upper TC assembly, an upper sleeve, an upper seal assembly, etc. The transmission shaft and the lower seal assembly, the lower sleeve, the lower housing, the upper housing, the upper sleeve, and the upper seal assembly together form a closed space, which is first evacuated and then filled with lubricating oil. The lower TC assembly, the liquid dynamic pressure thrust bearing group assembly, and the upper TC assembly work in oil, which improves the working environment. The liquid dynamic pressure thrust bearing group assembly uses two groups of upper and lower liquid dynamic pressure thrust bearing groups to jointly bear the axial impact load, and has a low friction coefficient and a high load-bearing capacity. Compared with the existing screw drill transmission shaft assembly, it has the advantages of compact size, simple structure, good sealing effect, and strong resistance to axial impact loads.

Description

Technical field:

[0001] The present invention relates to the field of a transmission shaft assembly for a screw drill, and in particular to a transmission shaft assembly for a screw drill using a liquid dynamic pressure thrust bearing group and a liquid dynamic pressure seal. Background technology:

[0002] Screw drill tools are one of the most widely used downhole power drilling tools in oil drilling and workover operations. They primarily consist of a bypass valve assembly, a motor assembly, a universal joint assembly, and a drive shaft assembly. With the continuous deepening of oilfield exploration and development, the drilling of complex wells, such as deep and ultra-deep wells, horizontal wells, and extended-reach wells, is increasing. This places increasing demands on screw drill tools, such as longer service life, improved impact resistance, higher torque output, and greater overload capacity. This necessitates continuous advancements in screw drill tool research and application technology to enhance screw performance and meet on-site requirements.

[0003] The drive shaft assembly of a screw drill tool primarily consists of a drive shaft, drive shaft housing, radial bearings, and thrust bearing groups. Currently, most screw drill tool drive shaft assemblies utilize an open structure, meaning the radial bearings and thrust bearing groups operate in a drilling fluid environment lubricated and cooled by the drilling fluid. However, the drilling fluid contains highly abrasive solid particles, which accelerates wear of the radial bearings and thrust bearing group, significantly reducing the service life of the drive shaft assembly. Furthermore, the thrust bearing group utilizes a deep groove ball bearing string, which has limited axial load-bearing capacity and is susceptible to damage when subjected to strong impact loads in hard formations.

[0004] In recent years, some domestic units have carried out research on oil-sealed drive shaft assemblies and applied for patents. For example, the Chinese invention patent "Automatic Pressure-Regulating Oil-Sealed Drive Shaft Assembly" (Patent No. ZL 200810154096.1) discloses an oil-sealed drive shaft structure. Both the upper and lower seal assemblies have a pressure-regulating function to maintain the balance between the internal pressure and the external drilling fluid pressure. However, the drive shaft is divided into two parts, the upper and lower parts have a complex structure, and both the upper and lower seals use ordinary seals, which are difficult to adapt to the high-pressure drilling fluid environment downhole, affecting the sealing effect and service life.

[0005] The invention patent "A screw drill drive shaft assembly with high sealing performance" (patent number ZL200810045153.2) discloses a knife-edge sealing device. Compared with the piston-type compensating seal, the compensation amount of this sealing compensation form is small and the sealing life is short.

[0006] The current domestic screw drill thrust bearing group uses a deep groove ball rolling bearing string, and no literature or patents using a liquid dynamic pressure thrust bearing group have been retrieved. Summary of the invention:

[0007] The purpose of the present invention is to address the problems existing in the prior art and provide a screw drill drive shaft device with better sealing effect and stronger resistance to axial impact loads, thereby increasing the service life of the drive shaft and reducing drilling costs, and adopting a screw drill drive shaft assembly using a liquid dynamic pressure thrust bearing group and a liquid dynamic pressure seal.

[0008] In order to achieve the above object, the technical solution adopted by the present invention to solve this technical problem is:

[0009] A screw drill drive shaft assembly using a liquid dynamic pressure thrust bearing group and a liquid dynamic pressure seal comprises a drive shaft and a lower sleeve, a lower seal assembly, a lower housing, a lower TC assembly, a liquid dynamic pressure thrust bearing group assembly, an upper TC assembly, an upper housing, an upper seal assembly and an upper sleeve, which are sequentially mounted on the outside of the drive shaft from bottom to top; the upper end of the lower housing is fixedly connected to the lower end of the upper housing, the upper end of the upper housing is provided with a connection end for the screw drill universal shaft housing, the lower end of the drive shaft is provided with a connection end for the drill bit, and the upper end of the drive shaft is provided with a connection end for the screw drill universal shaft; wherein: the drive shaft, the lower housing, the upper housing, the upper seal assembly, the lower seal assembly, the lower sleeve and the upper sleeve are combined to form a closed space, the lower TC assembly, the liquid dynamic pressure thrust bearing group assembly and the upper TC assembly are sequentially mounted on the drive shaft in the closed space from bottom to top, an oil filling hole is radially provided on the outer shell of the upper housing, the oil filling hole is connected to the closed space, and a sealing head is provided outside the oil filling hole.

[0010] The liquid dynamic pressure thrust bearing group assembly consists of an upper liquid dynamic pressure thrust bearing group, a spacer ring, a spacer ring sleeve, a lower liquid dynamic pressure thrust bearing group and multiple pins; the upper liquid dynamic pressure thrust bearing group consists of a fixed shoe B, a thrust ring B and a connecting ring B, and the lower liquid dynamic pressure thrust bearing group consists of a fixed shoe A, a thrust ring A and a connecting ring A; wherein, the spacer ring consists of two half rings, which are fastened together and installed on the transmission shaft with an interference fit using a spacer ring sleeve; the fixed shoe B is fixed to the upper shell body by a pin and is stationary, and the fixed shoe A is fixed to the lower shell body by a pin; the thrust ring B, the connecting ring B and the thrust ring A, the connecting ring A are all fixed by pins and the spacer ring, and rotate with the transmission shaft.

[0011] The upper TC assembly consists of an upper bearing inner ring and an upper bearing outer ring; the lower TC assembly consists of a lower bearing inner ring and a lower bearing outer ring; one or more straight grooves or spiral grooves are arranged on the outer surfaces of the upper bearing inner ring and the lower bearing inner ring, or on the inner surfaces of the upper bearing outer ring and the lower bearing outer ring.

[0012] The upper sealing assembly consists of an upper piston, a shaft seal B, a hole seal B and an O-ring C; the lower sealing assembly consists of a lower piston, a shaft seal A, a hole seal A and an O-ring A; the upper sealing assembly can move axially relative to the upper housing and the upper sleeve, and the lower sealing assembly can move axially relative to the lower housing and the lower sleeve; the shaft seals B and A are special liquid dynamic pressure seals; the hole seals B and A are car-type seals.

[0013] The upper sleeve and the lower sleeve are interference fitted on the transmission shaft. The outer surfaces of the two sleeves are sprayed with a nickel-based carbide coating with a thickness of 0.1 to 0.4 mm, and the surface hardness of the coating reaches 70 to 75 HRC.

[0014] Compared with the existing screw drill transmission shaft, the present invention has the following advantages:

[0015] (1) In the upper and lower sealing assemblies, the rotary dynamic seal between the piston and the sleeve adopts a special liquid dynamic pressure seal, the sliding seal between the piston and the outer shell adopts a car-type seal with high anti-pollution ability, and the sleeve surface is sprayed with a high-hardness nickel-based carbide coating to improve the wear resistance of the sleeve. The use of such a sealing structure can improve the sealing effect and have a longer service life.

[0016] (2) The thrust bearing group adopts a liquid dynamic pressure thrust bearing group, which has better impact resistance and axial load capacity than the conventional deep groove ball thrust bearing group. At the same time, the structure is more compact, shortening the length of the drive shaft assembly and improving the performance of the drive shaft assembly. Description of the drawings:

[0017] Figure 1 This is a structural sectional view of a screw drill transmission shaft assembly that uses a liquid dynamic pressure thrust bearing group and a liquid dynamic pressure seal according to the present invention.

[0018] Markings in the figure:

[0019] 1. Drive shaft, 2. Hole seal A, 3. Shaft seal A, 4. Lower piston, 5. Lower sleeve, 6. O-ring A, 7. Lower housing, 8. Lower bearing outer ring, 9. Lower bearing inner ring, 10. O-ring B, 11. Pin, 12. Fixing shoe A, 13. Groove A, 14. Thrust ring A, 15. Connecting ring A, 16. Spacer ring, 17. Spacer ring, 18. Connecting ring B, 19. Thrust ring B, 20. Fixing shoe B, 21. Groove B, 22. Oil filling hole, 23. Upper bearing outer ring, 24. Upper bearing inner ring, 25. Upper housing, 26. O-ring C, 27. Upper sleeve, 28. Upper piston, 29. Shaft seal B, 30. Hole seal B. Specific implementation method:

[0020] The following is a further detailed description with reference to the accompanying drawings.

[0021] Example 1

[0022] Refer to the attached Figure 1 A screw drill drive shaft assembly using a liquid dynamic pressure thrust bearing group and a liquid dynamic pressure seal comprises a drive shaft 1 and a lower sleeve 5, a lower seal assembly, a lower housing 7, a lower TC assembly, a liquid dynamic pressure thrust bearing group assembly, an upper TC assembly, an upper housing 25, an upper seal assembly and an upper sleeve 27, which are sequentially sleeved on the outside of the drive shaft 1 from bottom to top; wherein the upper end of the lower housing 7 is fixedly connected to the lower end of the upper housing 25, the upper end of the upper housing 25 is provided with a connection end to the screw drill universal shaft housing, and the lower end of the drive shaft 1 is provided with a connection end to the screw drill universal shaft housing. The drill bit connection end and the upper end of the transmission shaft 1 are provided with a universal shaft connection end for connecting the screw drill tool; it is characterized in that: the transmission shaft 1 and the lower shell 7, the upper shell 25, the upper seal assembly, the lower seal assembly, the lower sleeve 5, and the upper sleeve 27 are combined to form a closed space, and the lower TC assembly, the liquid dynamic pressure thrust bearing group assembly and the upper TC assembly are installed on the transmission shaft 1 in the closed space from bottom to top, and an oil filling hole 22 is radially provided on the outer shell of the upper shell 25, the oil filling hole 22 is connected to the closed space, and a sealing head is provided outside the oil filling hole 22.

[0023] Furthermore, the liquid dynamic pressure thrust bearing group assembly consists of an upper liquid dynamic pressure thrust bearing group, a spacer ring 17, a spacer ring sleeve 16, a lower liquid dynamic pressure thrust bearing group and multiple pins 11; the upper liquid dynamic pressure thrust bearing group consists of a fixed shoe B20, a thrust ring B19 and a connecting ring B18, and the lower liquid dynamic pressure thrust bearing group consists of a fixed shoe A12, a thrust ring A14 and a connecting ring A15; wherein, the spacer ring 17 consists of two half rings, which are fastened together and then installed on the transmission shaft 1 with an interference fit using a spacer ring sleeve 16; the fixed shoe B20 is fixed to the upper shell 25 by the pin 11 and is stationary, and the fixed shoe A12 is fixed to the lower shell 7 by the pin 11; the thrust ring B19, the connecting ring B18 and the thrust ring A14, the connecting ring A15 are all fixed to the spacer ring 17 by the pin 11 and rotate with the transmission shaft 1.

[0024] Furthermore, the upper TC assembly is composed of an upper bearing inner ring 24 and an upper bearing outer ring 23; the lower TC assembly is composed of a lower bearing inner ring 9 and a lower bearing outer ring 8; one or more straight grooves or spiral grooves are arranged on the outer surfaces of the upper bearing inner ring 24 and the lower bearing inner ring 9, or on the inner surfaces of the upper bearing outer ring 23 and the lower bearing outer ring 8.

[0025] Furthermore, the upper sealing assembly is composed of an upper piston 28, a shaft seal B29, a hole seal B30 and an O-ring C26; the lower sealing assembly is composed of a lower piston 4, a shaft seal A3, a hole seal A2 and an O-ring A6; the upper sealing assembly can move axially relative to the upper housing 25 and the upper sleeve 27, and the lower sealing assembly can move axially relative to the lower housing 7 and the lower sleeve 5; the shaft seal B29 and the shaft seal A3 are special liquid dynamic pressure seals; the hole seal B30 and the hole seal A2 are vehicle-type seals.

[0026] Furthermore, the upper sleeve 27 and the lower sleeve 5 are interference fitted on the transmission shaft 1 , and the outer surfaces of the two sleeves are sprayed with a nickel-based carbide coating with a thickness of 0.1 to 0.4 mm, and the surface hardness of the coating reaches 70 to 75 HRC.

[0027] Typical embodiments

[0028] comparison Figure 1 The screw drill drive shaft assembly of the present invention, which utilizes a hydrodynamic thrust bearing assembly and a hydrodynamic seal, primarily comprises a drive shaft 1, a lower seal assembly, a lower sleeve 5, a lower housing 7, a lower TC assembly, a hydrodynamic thrust bearing assembly, an upper housing 25, an upper TC assembly, an upper sleeve 27, and an upper seal assembly.

[0029] The upper end of the lower housing 7 and the lower end of the upper housing 25 are threadedly connected. The upper end of the upper housing 25 is connected to the screw drill universal joint housing. The lower end of the drive shaft 1 is connected to the drill bit, and the upper end is connected to the screw drill universal joint. The drive shaft 1, lower housing 7, upper housing 25, upper seal assembly, lower seal assembly, lower bushing 5, and upper bushing 27 form a closed space. Within this closed space, the lower TC assembly, the hydrodynamic thrust bearing assembly, and the upper TC assembly are mounted on the drive shaft 1 in order from bottom to top. An oil filling port 22 is provided on the outer shell of the upper housing 25. This port is used to evacuate the closed space before oil is added. The advantage of evacuating the closed space before oiling is that it prevents air contained in the closed space from expanding under the high-temperature and high-pressure environment downhole, potentially causing seal failure. Once the closed space is filled with lubricating oil, the upper and lower TC assemblies and the hydrodynamic thrust bearing assembly operate in an oily environment, significantly extending the lifespan of the radial and thrust bearings.

[0030] The upper seal assembly consists of the upper piston 28, shaft seal B29, bore seal B30, and O-ring C26; the lower seal assembly consists of the lower piston 4, shaft seal A3, bore seal A2, and O-ring A6. The upper seal assembly is axially movable relative to the upper housing 25 and upper sleeve 27, while the lower seal assembly is axially movable relative to the lower housing 7 and lower sleeve 5. Shaft seals B29 and A3 are specialized hydrodynamic seals adapted to the downhole drilling fluid environment; bore seals B30 and A2 are highly contamination-resistant, vehicle-type seals. Hydrodynamic seals operate by utilizing the hydrodynamic effect to form a hydrodynamic oil film between the dynamic sealing surfaces, preventing direct contact between the relatively moving surfaces. Since shaft seals A29 and B3 operate on this oil film, wear and friction are significantly reduced. Because a lubricating film must form on the friction surface, a certain amount of lubricating oil leakage is required. This leakage loss is compensated by the axial movement of the upper and lower seal assemblies, thereby maintaining a constant balance between internal pressure and external drilling fluid pressure. The A2 and B30 bore seals utilize a J-shaped sliding ring seal (a cart-type seal structure). This cart-type seal is characterized by ultrahigh pressure resistance, impact resistance, long life, suitability for harsh working conditions, and strong anti-contamination capabilities. It is particularly suitable for downhole high-temperature and high-pressure drilling fluid environments.

[0031] The upper sleeve 27 and the lower sleeve 5 are assembled on the transmission shaft 1 with interference fit. The outer surfaces of the two sleeves are sprayed with a nickel-based carbide coating with a thickness of 0.1 to 0.4 mm. The surface hardness of the coating reaches above 70HRC. The high hardness coating improves the wear resistance of the sleeve.

[0032] By adopting the above-mentioned special liquid dynamic pressure seal for the shaft, the lathe-type J-shaped sliding ring seal for the hole, and the high wear-resistant shaft sleeve, the sealing effect is greatly improved and the sealing life is extended.

[0033] The upper TC assembly consists of an upper bearing inner ring 24 and an upper bearing outer ring 23; the lower TC assembly consists of a lower bearing inner ring 9 and a lower bearing outer ring 8. The upper bearing inner ring 24 and the lower bearing inner ring 9 are interference-fitted onto the transmission shaft 1, the upper bearing outer ring 23 is interference-fitted within the upper housing 25, and the lower bearing outer ring 8 is interference-fitted within the lower housing 7. One or more straight or spiral grooves are arranged on the outer surfaces of the upper bearing inner ring 24 and the lower bearing inner ring 9, or on the inner surfaces of the upper bearing outer ring 23 and the lower bearing outer ring 8. These grooves ensure smooth lubrication within the enclosed space and maintain internal and external pressure balance.

[0034] The liquid dynamic pressure thrust bearing group assembly consists of an upper liquid dynamic pressure thrust bearing group, a lower liquid dynamic pressure thrust bearing group, a spacer ring 17, a spacer ring sleeve 16 and multiple pins 11; the upper liquid dynamic pressure thrust bearing group consists of a fixed shoe B20, a thrust ring B19 and a connecting ring B18, and the lower liquid dynamic pressure thrust bearing group consists of a fixed shoe A12, a thrust ring A14 and a connecting ring A15; the spacer ring 17 consists of two half rings, which are fastened together and then installed on the transmission shaft 1 with an interference fit using a spacer ring sleeve 16; the fixed shoe B20 is fixed and stationary to the upper shell 25 by the pin 11, and the fixed shoe A12 is fixed and stationary to the lower shell 7 by the pin 11; the thrust ring B19, the connecting ring B18, the thrust ring A14 and the connecting ring A15 are all fixed to the spacer ring 17 by the pin 11 and rotate with the transmission shaft 1.

[0035] The surface of the stationary shoe B20 (the side that contacts the thrust ring B19) is decorated with multiple (generally more than three) radial grooves B21. The surface of the stationary shoe A12 (the side that contacts the thrust ring A14) is decorated with multiple (generally more than three) radial grooves A13. The radial grooves B21 on the surface of the stationary shoe B20 and the radial grooves A13 on the surface of the stationary shoe A12 store a certain amount of lubricating oil, forming a dynamic oil film on the relative moving surfaces between the stationary shoe B20 and the thrust ring B19, and between the stationary shoe A12 and the thrust ring A14. This oil film generates pressure to withstand loads, forming a hydrodynamic thrust bearing. Compared to rolling bearings and ordinary sliding bearings, hydrodynamic thrust bearings have the advantages of low friction coefficient, high load-bearing capacity, small size, compact structure, and long service life.

Claims

1. A screw drill transmission shaft assembly using a liquid dynamic pressure thrust bearing group and a liquid dynamic pressure seal, comprising a transmission shaft (1) and a lower sleeve (5) which is sequentially sleeved on the outside of the transmission shaft (1) from bottom to top, a lower seal assembly, a lower housing (7), a lower TC assembly, a liquid dynamic pressure thrust bearing group assembly, an upper TC assembly, an upper housing (25), an upper seal assembly and an upper sleeve (27); wherein the upper end of the lower housing (7) and the lower end of the upper housing (25) are fixedly connected, the upper end of the upper housing (25) is provided with a connection end to a screw drill universal shaft housing, the lower end of the transmission shaft (1) is provided with a connection end to a drill bit, and the upper end of the transmission shaft (1) is provided with a connection end to a screw drill universal shaft; and characterized in that: The transmission shaft (1) is combined with the lower housing (7), the upper housing (25), the upper sealing assembly, the lower sealing assembly, the lower sleeve (5), and the upper sleeve (27) to form a closed space. The lower TC assembly, the liquid dynamic pressure thrust bearing assembly, and the upper TC assembly are sequentially installed on the transmission shaft (1) in the closed space from bottom to top. An oil filling hole (22) is radially provided on the outer shell of the upper housing (25). The oil filling hole (22) is communicated with the closed space, and a plugging head is provided outside the oil filling hole (22). The liquid dynamic pressure thrust bearing assembly consists of an upper liquid dynamic pressure thrust bearing assembly, a spacer ring (17), a spacer ring sleeve (16), a lower liquid dynamic pressure thrust bearing assembly, and a plurality of pins (11). The upper liquid dynamic pressure thrust bearing assembly consists of a fixed bushing B (20), a thrust ring B (19), and a connecting ring B (18). The lower liquid dynamic pressure thrust bearing assembly consists of a fixed bushing A (12), a thrust ring A (14), connecting ring A (15); wherein, the spacer ring (17) is composed of two half rings, which are fitted on the transmission shaft (1) with a spacer ring sleeve (16) after being buckled together; the fixed shoe B (20) is fixed and stationary with the upper shell (25) through the pin (11), and the fixed shoe A (12) is fixed and stationary with the lower shell (7) through the pin (11); the thrust ring B (19), connecting ring B (18) and thrust ring A (14), connecting ring A (15) are all fixed to the spacer ring (17) through the pin (11) and rotate with the transmission shaft (1); the surface of the fixed shoe B (20), that is, the side in contact with the thrust ring B (19), is provided with a plurality of radially distributed grooves B (21); the surface of the fixed shoe A (12), that is, the side in contact with the thrust ring A (14), is provided with a plurality of radially distributed grooves A (13).

2. The screw drill drive shaft assembly using a hydrodynamic thrust bearing group and a hydrodynamic seal according to claim 1, characterized in that: The upper TC assembly is composed of an upper bearing inner ring (24) and an upper bearing outer ring (23); the lower TC assembly is composed of a lower bearing inner ring (9) and a lower bearing outer ring (8); one or more straight grooves or spiral grooves are arranged on the outer surfaces of the upper bearing inner ring (24) and the lower bearing inner ring (9), or on the inner surfaces of the upper bearing outer ring (23) and the lower bearing outer ring (8).

3. The screw drill drive shaft assembly using a hydrodynamic thrust bearing group and a hydrodynamic seal according to claim 1 or 2, characterized in that: The upper sealing assembly is composed of an upper piston (28), a shaft seal B (29), a hole seal B (30) and an O-ring C (26); the lower sealing assembly is composed of a lower piston (4), a shaft seal A (3), a hole seal A (2) and an O-ring A (6); the upper sealing assembly is movable in the axial direction relative to the upper housing (25) and the upper shaft sleeve (27), and the lower sealing assembly is movable in the axial direction relative to the lower housing (7) and the lower shaft sleeve (5); the shaft seal B (29) and the shaft seal A (3) are special liquid dynamic pressure seals; the hole seal B (30) and the hole seal A (2) are vehicle-type seals.

4. The screw drill drive shaft assembly using a hydrodynamic thrust bearing group and a hydrodynamic seal according to claim 1 or 2, characterized in that: The upper sleeve (27) and the lower sleeve (5) are interference-fitted on the transmission shaft (1). The outer surfaces of the two sleeves are sprayed with a nickel-based carbide coating with a thickness of 0.1 to 0.4 mm, and the surface hardness of the coating reaches 70 to 75 HRC.

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