A transmission mechanism of a rack and pinion underground tractor

Abstract

The utility model relates to a transmission mechanism of underground tractor, concretely relates to a transmission mechanism of rack and pinion underground tractor. The transmission mechanism of rack and pinion underground tractor, it is by tool casing, wedge rack, support connector and drive assembly constitute: the mutual fixed connection of symmetrically arranged tool casing through support connector; each support connector is symmetrically movable and is installed with drive assembly; the inside movable mounting of support connector has wedge rack; wedge rack and drive assembly meshed connection. The transmission mechanism of rack and pinion underground tractor simple structure, reliable operation can intermittently pass through friction wheel drive the whole tractor and advance, solved the problem that the existing tractor has reduced the drilling efficiency and the tool conveying capacity, met the need of enterprise use.

Description

Technical Field

[0001] This utility model relates to a transmission mechanism for a downhole traction device, specifically a transmission mechanism for a gear and rack downhole traction device. Background Technology

[0002] In the field of petroleum engineering, horizontal well exploration and development can maximize the exposure of oil and gas reservoirs, significantly improve oil and gas extraction efficiency and ultimate recovery rate. Horizontal well technology has become the mainstream engineering technology for global exploration and development. Moreover, unconventional resources such as shale gas, due to their tight reservoirs and low permeability, are almost entirely explored, developed, and produced using horizontal wells. In my country, the horizontal displacement of shale gas development is around 2000m, while abroad it reaches 3000m, with some well shapes even resembling fishhooks. With the increase in horizontal displacement and horizontal sections of these wells, the issue of downhole extension has become a key technology and bottleneck restricting operational capabilities. Existing long-distance horizontal well traction devices not only increase tubing friction, reduce drilling efficiency and tool delivery capacity, but may also, in severe cases, lead to insufficient drilling depth or failure to deliver tools to the target location. Summary of the Invention

[0003] The purpose of this utility model is to provide a simple and easy-to-use transmission mechanism for a gear and rack downhole traction device that solves the problems of reduced drilling efficiency and tool delivery capacity in existing traction devices.

[0004] The technical solution of this utility model is: A transmission mechanism for a rack and pinion downhole traction device comprises a tool casing, a wedge-shaped rack, a support connector, and a drive assembly; characterized in that: the tool casings arranged symmetrically are fixedly connected to each other through support connectors; the drive assembly is symmetrically and movably mounted on each support connector; a wedge-shaped rack is movably mounted inside the support connector; and the wedge-shaped rack is meshed with the drive assembly.

[0005] One end of the wedge-shaped rack is tapered; the middle part of the two sides of the wedge-shaped rack is provided with clearance grooves, and the wedge-shaped rack on both sides of the clearance grooves is provided with drive teeth.

[0006] The support pipe consists of two pipe joints, an assembly plate, and a limiting block; the two pipe joints are arranged symmetrically; the pipe joints are fixedly connected by the symmetrically arranged assembly plates; each assembly plate has a U-shaped opening arranged symmetrically, and a limiting block is provided at the upper end of each U-shaped opening; a drive assembly is installed in the U-shaped opening below the limiting block.

[0007] Each of the aforementioned pipe joints is equipped with a buffer spring inside.

[0008] The drive assembly consists of a drive shaft, a positioning collar, a one-way bearing, a friction wheel, and a drive gear. The drive shaft, which is stepped, has a one-way bearing mounted in the middle via a flat key. A friction wheel is mounted on the circumference of the one-way bearing. Drive gears are mounted on both sides of the one-way bearing via flat keys. A positioning collar is mounted on one side of each drive gear via a snap ring, and each positioning collar is in contact with the drive gear on one side.

[0009] Each positioning collar is provided with an assembly ring groove, and the positioning collar is movably connected to the U-shaped opening through the assembly ring groove; a return spring is provided between the limit block and the positioning collar.

[0010] The advantages of this utility model are: The transmission mechanism of this rack and pinion downhole traction device is simple in structure and reliable in operation. It can intermittently drive the entire traction device forward through the friction wheel, which solves the problems of reduced drilling efficiency and tool delivery capacity of existing traction devices and meets the needs of enterprises. Attached Figure Description

[0011] Figure 1 This is a schematic diagram of the structure of this utility model; Figure 2 for Figure 1 Schematic diagram of the structure in the AA direction; Figure 3 for Figure 1 Schematic diagram of the structure in the middle BB direction; Figure 4 This is a schematic diagram of the drive assembly of this utility model; Figure 5 This is a schematic diagram of the main structure of the wedge-shaped rack of this utility model; Figure 6 This is an isometric structural diagram of the wedge-shaped rack of this utility model; Figure 7 This is an isometric structural diagram of the support pipe of this utility model; Figure 8 This is a front view schematic diagram of the support pipe of this utility model.

[0012] In the diagram: 1. Tool sleeve, 2. Wedge rack, 3. Support pipe, 4. Clearance groove, 5. Drive gear, 6. Pipe joint, 7. Assembly plate, 8. Limiting block, 9. U-shaped opening, 10. Buffer spring, 11. Drive shaft, 12. Positioning collar, 13. One-way bearing, 14. Friction wheel, 15. Drive gear, 16. Assembly ring groove, 17. Snap ring. Detailed Implementation

[0013] The transmission mechanism of the rack and pinion downhole traction device consists of a tool casing 1, a wedge rack 2, a support pipe 3, and a drive assembly: the tool casings 1, which are arranged symmetrically, are fixedly connected to each other through the support pipe 3.

[0014] The support pipe 3 consists of two pipe joints 6, an assembly plate 7, and a limiting block 8; the two pipe joints 6 are arranged symmetrically; each pipe joint 6 is threadedly connected to the corresponding tool sleeve 1.

[0015] The pipe fittings 6 are fixedly connected by symmetrically arranged assembly plates 7; each assembly plate 7 has a symmetrically arranged U-shaped opening 9, and each U-shaped opening 9 has a limit stop 8 at its upper end (see the instruction manual appendix). Figure 7 and 8 ).

[0016] The drive assembly is housed in the U-shaped opening 9 below the limit stop 8. The drive assembly consists of a drive shaft 11, a positioning collar 12, a one-way bearing 13, a friction wheel 14, and a transmission gear 15. The one-way bearing 13 is mounted in the middle of the stepped shaft 11 via a flat key. The friction wheel 14 is mounted on the circumferential surface of the one-way bearing 13.

[0017] When the drive shaft 11 rotates forward, the drive shaft 11 can drive the outer ring and friction wheel 14 to rotate together through the inner ring of the one-way bearing 13; when the drive shaft 11 rotates in reverse and drives the inner ring of the one-way bearing 13 to rotate, the inner ring of the one-way bearing 13 cannot transmit torque to the outer ring and friction wheel 14, thus preventing the drive shaft 11 from driving the friction wheel 14 to rotate when it rotates in reverse.

[0018] One-way bearing 13 has drive gears 15 mounted on both sides via flat keys; each drive gear 15 has a locating collar 12 mounted on one side via a snap ring 17, and each locating collar 12 is in contact with the drive gear 15 on one side (see instruction manual appendix). Figure 4 With this configuration, when the drive shaft 11 rotates, it can drive the drive gear 15, the positioning collar 12, and the one-way bearing 13 to rotate synchronously.

[0019] Each positioning collar 12 is provided with an assembly ring groove 16, and the positioning collar 12 is movably connected to the U-shaped opening 9 through the assembly ring groove 16. The purpose of providing the assembly ring groove 16 is to limit each drive assembly within the U-shaped opening 9, so that the drive assembly can only move up and down within the U-shaped opening 9.

[0020] A return spring (not shown in the figure) is provided between the limit stop 8 and the positioning collar 12. The purpose of providing the return spring is to ensure that each drive assembly maintains a tendency to move towards the center under the elastic force of the return spring, thereby forcing the transmission gear 15 of each drive assembly to always maintain meshing with the drive teeth 5 on the wedge rack 2.

[0021] Each pipe joint 6 is equipped with a buffer spring 10. The purpose of the buffer spring 10 is to provide a certain buffering force to the wedge rack 2 when it reaches its limit position during reciprocating motion, so as to avoid damage when the two ends of the wedge rack 2 directly contact the pipe joint 6.

[0022] The support pipe 3 has a wedge-shaped rack 2 installed inside; one end of the wedge-shaped rack 2 is tapered; the middle part of the two sides of the wedge-shaped rack 2 is provided with relief grooves 4 respectively. The purpose of setting the relief grooves 4 is to provide movement space for the friction wheel 14 so that the friction wheel 14 can move freely during the movement of the drive assembly, thereby avoiding the problem of the wedge-shaped rack 2 hindering the rotation of the friction wheel 14.

[0023] Drive teeth 5 are provided on the wedge-shaped racks 2 on both sides of the clearance groove 4. Each drive tooth 5 on the wedge-shaped rack 2 meshes with the transmission gear 15 on the corresponding drive assembly. During the reciprocating motion of the wedge-shaped rack 2, the drive teeth 5 and the transmission gear 15 can drive the corresponding drive assembly to move.

[0024] When the transmission mechanism of the rack and pinion downhole traction device is working, the wedge-shaped rack 2 inside it moves back and forth continuously under the action of other components.

[0025] During the movement of the wedge-shaped rack 2 from right to left, the drive teeth 5 on its side drive the transmission gear 15 of the corresponding drive assembly to rotate, thereby driving the transmission shaft 11 to rotate clockwise. During the clockwise rotation of the transmission shaft 11, the friction wheel 14 rotates through the one-way bearing 13. At the same time, during this process, the wedge-shaped rack 2 gradually transitions from a thin section to a thick section, driving the corresponding drive assembly to move; thereby pushing each drive assembly to expand radially. When the thick section of the wedge-shaped rack 2 contacts each drive assembly, each drive assembly is expanded to its maximum position. At this time, the friction wheel 14 of each drive assembly contacts the oil well casing. Subsequently, under the friction action of the rotating friction wheel 14, the transmission mechanism is driven to move forward as a whole inside the oil well casing.

[0026] After the wedge rack 2 moves to its extreme left position, it moves from left to right. During this process, the wedge rack 2 drives the corresponding drive assembly's transmission gear 15 and drive shaft 11 to reverse direction via the drive teeth 5. During the reverse rotation of the drive shaft 11, the inner ring of the one-way bearing 13 rotates, preventing the inner ring of the one-way bearing 13 from transmitting torque to the outer ring and friction wheel 14. Thus, the transmission mechanism remains in a fixed position within the well casing. Simultaneously, during this process, the wedge rack 2 gradually transitions from a thick section to a thin section, driving the corresponding drive assembly to move. At this point, under the action of the return spring, each drive assembly retracts inward and disengages from the well casing.

[0027] When the wedge rack 2 moves to its limit position to the right, each drive assembly remains connected to the thinnest end of the wedge rack 2, and at this time each drive assembly returns to its initial state; thus, during the continuous back-and-forth movement of the wedge rack 2, the transmission mechanism can drive the entire traction device to move intermittently within the oil well casing.

[0028] The transmission mechanism of this rack and pinion downhole traction device is simple in structure and reliable in operation. It can intermittently drive the entire traction device forward through the friction wheel, which solves the problems of reduced drilling efficiency and tool delivery capacity of existing traction devices and meets the needs of enterprises.

Claims

1. A transmission mechanism for a rack and pinion downhole traction device, comprising a tool casing (1), a wedge-shaped rack (2), a support pipe (3), and a drive assembly; characterized in that: The tool sleeves (1) arranged symmetrically are fixedly connected to each other by support tubes (3); each support tube (3) is symmetrically and movably mounted with a drive assembly; a wedge rack (2) is movably mounted inside the support tube (3); the wedge rack (2) is meshed with the drive assembly.

2. The transmission mechanism of a gear and rack downhole traction device according to claim 1, characterized in that: One end of the wedge-shaped rack (2) is conical; the middle part of the two sides of the wedge-shaped rack (2) is provided with clearance grooves (4), and the wedge-shaped rack (2) on both sides of the clearance grooves (4) is provided with driving teeth (5).

3. The transmission mechanism of a gear and rack downhole traction device according to claim 2, characterized in that: The support pipe (3) consists of two pipe joints (6), an assembly plate (7) and a limiting block (8); the two pipe joints (6) are arranged symmetrically; the pipe joints (6) are fixedly connected by the symmetrically arranged assembly plate (7); each assembly plate (7) is symmetrically arranged with a U-shaped opening (9), and the upper end of each U-shaped opening (9) is provided with a limiting block (8); the U-shaped opening (9) below the limiting block (8) contains a drive assembly.

4. The transmission mechanism of a gear and rack downhole traction device according to claim 3, characterized in that: Each of the aforementioned pipe joints (6) is equipped with a buffer spring (10).

5. The transmission mechanism of a gear and rack downhole traction device according to claim 4, characterized in that: The drive assembly consists of a drive shaft (11), a positioning collar (12), a one-way bearing (13), a friction wheel (14), and a drive gear (15). The drive shaft (11), which is in the form of a stepped shaft, is fitted with a one-way bearing (13) via a flat key in the middle. A friction wheel (14) is mounted on the circumferential surface of the one-way bearing (13). Drive gears (15) are mounted on both sides of the one-way bearing (13) via flat keys. A positioning collar (12) is mounted on one side of each drive gear (15) via a snap ring (17), and each positioning collar (12) is in contact with the drive gear (15) on one side.

6. The transmission mechanism of a gear and rack downhole traction device according to claim 5, characterized in that: Each positioning ring (12) is provided with an assembly ring groove (16), and the positioning ring (12) is movably connected to the U-shaped opening (9) through the assembly ring groove (16); a return spring is provided between the limiting block (8) and the positioning ring (12).

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