An automatically openable and closable sliding sleeve assembly

Abstract

The application provides a sliding sleeve assembly capable of automatic opening and closing, comprising an outer sleeve with a flow hole, a moving sleeve capable of opening and closing the flow hole, a switch tool for driving the moving sleeve to move axially, the switch tool comprising a mounting mandrel, a limiting driving block, an elastic member and a driving control unit for controlling the moving direction of the switch tool, wherein the limiting driving block is radially telescopically mounted on the mounting mandrel through the elastic member; the driving control unit is mounted on one end of the mounting mandrel; the limiting driving block is extended into a limiting groove of the moving sleeve when the switch tool is lowered to a preset position, and drives the moving sleeve to move under the driving of the driving control unit. The application has the advantages of automatic opening and closing of the sliding sleeve, high operation efficiency, convenient tool lowering and taking out and the like.

Description

Technical Field

[0001] This invention relates to the field of well completion tools, and more particularly to an automatically opening and closing sliding sleeve assembly. Background Technology

[0002] Switchable sliding sleeves are important downhole tools for well completion, mainly including completion sliding sleeves and staged fracturing sliding sleeves. Their primary applications include well completion operations such as stratified production, circulating well control, gas lift, and multi-stage mixed injection. Meanwhile, with the development of staged fracturing technology for unconventional oil and gas resources such as shale gas, low-permeability sandstone, and coalbed methane, the demand for selective production, staged water shut-off, and secondary fracturing is constantly increasing, leading to a growing need for the multiple-operation switching function of sliding sleeves.

[0003] Currently, the existing methods for opening the sliding sleeve initially mainly include ball-drop opening, mechanical opening, and differential pressure opening. Closing or reopening the sliding sleeve involves connecting specialized switching tools with equipment such as steel wire, drilling tools, tubing, or coiled tubing for operation. This operation not only requires large equipment such as drilling and workover rigs or coiled tubing trucks, but also involves complex and difficult operations, resulting in high operating costs and long operation times. This greatly limits the flexibility and applicability of sliding sleeve switching operations. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to overcome the shortcomings of the prior art and provide an automatic switch slide assembly that can open and close the slide independently, has high operating efficiency, and facilitates tool insertion and removal.

[0005] To solve the above-mentioned technical problems, the technical solution proposed by this invention is as follows:

[0006] An automatically opening and closing sliding sleeve assembly includes an outer sleeve with a flow hole, a movable sleeve capable of opening and closing the flow hole, and a switching tool for driving the movable sleeve to move axially. The switching tool includes a mounting mandrel, a limiting drive block, an elastic element, and a drive control unit for driving the switching tool to move. The limiting drive block is radially telescopically mounted on the mounting mandrel via the elastic element. The drive control unit is mounted on one end of the mounting mandrel. When the switching tool is lowered to a preset position, the limiting drive block extends into a limiting groove of the movable sleeve and drives the movable sleeve to move under the drive of the drive control unit.

[0007] As a further improvement to the above technical solution:

[0008] It also includes a sensor that generates a sensing signal when the switching tool is lowered into place; the drive control unit includes a bidirectional turbine, a control section and a turbine housing, the two ends of the control section are respectively connected to the bidirectional turbine and the mounting mandrel, the turbine housing is located at the head end of the bidirectional turbine, the control section is controlled by the sensor, the control section receives the sensing signal from the sensor and controls the rotation direction of the bidirectional turbine.

[0009] A limiting component is provided between the worm gear housing and the outer sleeve to fix the lowering position of the switch tool, and the sensor is located at the limiting component.

[0010] The limiting component includes a pointed limiting boss and limiting grooves adapted to both sides of the pointed limiting boss. The pointed end of the pointed limiting boss faces the downward direction of the switching tool. The limiting groove includes a flared mating section and a straight clearance section that are interconnected. The sensor is located at both sides of the pointed limiting boss and generates a sensing signal when the pointed limiting boss and the limiting groove are engaged in a limiting action.

[0011] The outer surface of the limiting drive block is provided with an upper boss, and the upper and lower end faces of the upper boss are both extrusion slopes. The upper part of the outer sleeve is provided with a mating slope. When the limiting drive block moves upward to the mating slope and abuts against the upper end face of the upper boss, it retracts to disengage from the limiting groove of the moving sleeve.

[0012] The outer surface of the limiting drive block is provided with a lower boss. The upper end face of the lower boss and the upper end face of the limiting groove are limiting planes that mutually limit and cooperate when the moving sleeve moves. The lower end face of the lower boss and the lower end face of the limiting groove are extrusion slopes that facilitate the retraction of the limiting drive block.

[0013] The limiting drive blocks are arranged in multiple circumferentially along the mounting mandrel, and the mounting mandrel has the same number of mounting slots as the limiting drive blocks; the two ends of the limiting drive blocks are respectively radially limited in the mounting slots by a clamping sleeve; the clamping sleeve is installed at both ends of the mounting mandrel.

[0014] Each of the aforementioned limiting drive blocks is provided with at least two of the aforementioned elastic elements; the elastic elements are pre-pressed in the mounting groove and arranged along the axial direction of the limiting drive block.

[0015] The end of the mounting spindle furthest from the drive control unit is provided with a buoyancy cylinder to provide buoyancy and reduce movement resistance.

[0016] The outer sleeve includes an upper connector, an outer sleeve body, and a lower connector connected in sequence. The flow hole is located in the outer sleeve body, and the movable sleeve is axially movable and fitted inside the outer sleeve body.

[0017] Compared with the prior art, the advantages of the present invention are as follows:

[0018] The switching tool of this invention includes a mounting mandrel, a limit drive block, an elastic element, and a drive control unit. The drive control unit is mounted on one end of the mounting mandrel and can drive the switching tool to move and control its direction of movement. This allows the switching tool to autonomously descend along the tubing to the sliding sleeve, and to automatically close the sliding sleeve by changing its direction of movement. The switching tool can also autonomously separate from the sliding sleeve and return to the wellhead. The switching tool of this invention is self-powered, capable of autonomously moving to the sliding sleeve position and opening / closing it, and can automatically return to the wellhead.

[0019] Meanwhile, the limit drive block is radially telescopically mounted on the mounting spindle via an elastic element. This ensures that the limit drive block does not encounter obstruction when the switching tool moves up and down, and that it can disengage from the moving sleeve during the upward movement of the switching tool to complete the tool's return. Simultaneously, when the switching tool is lowered to the preset position, the limit drive block can extend into the limiting groove of the moving sleeve to provide the moving driving force for the moving sleeve, thereby closing the flow hole on the outer sleeve. Its ingenious structural design ensures reliable lowering and return of the switching tool while achieving the automatic opening and closing function of the sliding sleeve.

[0020] This invention is applicable to horizontal well segmented fracturing operations or well completion sliding sleeve operations. It eliminates the need to use special tubing strings such as drill strings, tubing, or coiled tubing to be run into the well when the sliding sleeve is closed and opened again, solving the problem that conventional sliding sleeve switching tools require the use of special equipment to be run in. This effectively improves the efficiency and flexibility of sliding sleeve switching, simplifies the operation process, and significantly reduces operation costs and time. Attached Figure Description

[0021] The invention will now be described in more detail with reference to embodiments and the accompanying drawings.

[0022] Figure 1 This is a schematic diagram of the automatic opening and closing sliding sleeve assembly of the present invention (with the switching tool in the lowered state).

[0023] Figure 2 This is a schematic diagram of the automatic opening and closing sliding sleeve assembly of the present invention (flow hole closed state).

[0024] Figure 3 This is a schematic diagram of the automatic opening and closing sliding sleeve assembly of the present invention (the switching tool is disengaged from the moving sleeve).

[0025] Figure 4 This is a three-dimensional structural diagram of the switching tool of the present invention.

[0026] Figure 5 This is a front sectional view of the switching tool of the present invention.

[0027] Figure 6 This is a three-dimensional structural diagram of the turbine housing of the present invention.

[0028] Figure 7 This is a schematic diagram showing the positional relationship between the outer sleeve and the movable sleeve of the present invention.

[0029] Figure 8 This is a schematic diagram of the limiting connector of the present invention.

[0030] The labels in the diagram represent:

[0031] 1. Outer sleeve; 11. Flow hole; 12. Mating bevel; 13. Upper connector; 14. Outer sleeve body; 15. Lower connector; 2. Moving sleeve; 21. Limiting groove; 3. Switch tool; 31. Mounting spindle; 311. Mounting groove; 32. Limiting drive block; 321. Upper boss; 322. Lower boss; 323. Extrusion bevel; 324. Limiting plane; 33. Elastic element; 34. Drive control unit; 341. Bidirectional turbine; 342. Control section; 343. Turbine housing; 35. Pressing sleeve; 36. Buoyancy cylinder; 4. Limiting component; 41. Sharp-angled limiting boss; 42. Limiting groove; 421. Horn-shaped mating section; 422. Straight clearance section; 5. Sensor. Detailed Implementation

[0032] The present invention will now be described in further detail with reference to the accompanying drawings and specific embodiments, but this does not limit the scope of protection of the present invention.

[0033] like Figures 1 to 5 As shown, the automatically opening and closing sliding sleeve assembly of this embodiment includes an outer sleeve 1, a movable sleeve 2, and a switching tool 3. The outer sleeve 1 is provided with an overflow hole 11. The movable sleeve 2 moves axially along the outer sleeve 1 to open and close the overflow hole 11. The switching tool 3 drives the movable sleeve 2 to move axially. In this embodiment, the switching tool 3 includes a mounting mandrel 31, a limiting drive block 32, an elastic element 33, and a drive control unit 34. The drive control unit 34 is mounted at one end of the mounting mandrel 31. It can drive the switching tool 3 to move, control the direction of movement of the switching tool 3, so that the switching tool 3 can autonomously descend along the tubing to the sliding sleeve, and autonomously close the sliding sleeve by changing the direction of movement of the switching tool 3. The switching tool 3 can also autonomously separate from the sliding sleeve and return to the wellhead. The switching tool 3 of this invention is self-powered, capable of autonomously moving to the sliding sleeve position and opening and closing the sliding sleeve, and can automatically return to the wellhead.

[0034] Meanwhile, the limit drive block 32 is radially telescopically mounted on the mounting spindle 31 via the elastic element 33. This ensures that the limit drive block 32 will not encounter obstruction when the switching tool 3 moves up and down, and the limit drive block 32 can disengage from the moving sleeve 2 when the switching tool 3 moves up to complete the tool's return. At the same time, when the switching tool 3 is lowered into the preset position, the limit drive block 32 extends into the limiting groove 21 of the moving sleeve 2 to provide the moving driving force for the moving sleeve 2, thereby closing the flow hole 11 on the outer sleeve 1. Its ingenious structural design ensures reliable lowering and return of the switching tool 3 while realizing the automatic opening and closing function of the sliding sleeve.

[0035] This invention is applicable to horizontal well segmented fracturing operations or well completion sliding sleeve operations. It eliminates the need to use special tubing strings such as drill strings, tubing, or coiled tubing to be run into the well when the sliding sleeve is closed and opened again, solving the problem that conventional switching tools 3 require the use of special equipment to be run in. This effectively improves the efficiency and flexibility of sliding sleeve switching, simplifies the operation process, and significantly reduces operation costs and time.

[0036] like Figure 6 As shown, the automatically opening and closing sliding sleeve assembly includes a sensor 5, which generates a sensing signal when the switching tool 3 is lowered into position. Figure 4 and 5 As shown, the drive control unit 34 includes a bidirectional turbine 341, a control sub 342, and a turbine housing 343. The bidirectional turbine 341 can rotate in both directions, driving the switching tool 3 to move bidirectionally in the well fluid, providing power for the switching tool 3 to move back and forth in the well and to open and close the flow orifice 11. The two ends of the control sub 342 are connected to the bidirectional turbine 341 and the mounting spindle 31, respectively. The control sub 342 includes a power source and a control circuit. The power source provides the operating power for the bidirectional turbine 341, and the control circuit realizes the starting and reversing actions of the bidirectional turbine 341. The control sub 342 is also connected to a sensor 5, receiving the sensing signals from the sensor 5 and controlling the rotation direction of the bidirectional turbine 341. The turbine housing 343 is located at the head end of the bidirectional turbine 341.

[0037] When sensor 5 detects that the switching tool 3 has been lowered to a preset position, it generates a sensing signal and sends it to the control section 342 of the drive control unit 34. The control section 342 receives the sensing signal from sensor 5 and drives the bidirectional turbine 341 to rotate in the opposite direction. At this time, the switching tool 3 moves upward, and the limit drive block 32 of the switching tool 3 drives the moving sleeve 2 upward to close the flow hole 11. The switching tool 3 can continue to move upward to achieve the automatic retrieval function. At the same time, the drive control unit 34 of the present invention has a compact layout, simple structure, and realizes the automatic control function of the sliding sleeve assembly.

[0038] Furthermore, such as Figure 1As shown, a limiting component 4 is provided between the worm gear housing 343 and the outer sleeve 1. The limiting component 4 is used to fix the lowering position of the switching tool 3. After the outer sleeve 1 and the switching tool 3 are limited by the limiting component 4, the limiting drive block 32 extends exactly into the limiting groove 21 of the moving sleeve 2, so that the moving sleeve 2 can be effectively moved when the switching tool 3 moves upward. In this embodiment, the sensor 5 is provided at the limiting component 4. The sensor 5 generates a sensing signal when it is pressed by the limiting component 4 during the limiting engagement.

[0039] Furthermore, such as Figures 6 to 8 As shown, the limiting component 4 includes a pointed limiting boss 41 and a limiting groove 42. The pointed end of the pointed limiting boss 41 faces the downward direction of the switching tool 3. The pointed limiting boss 41 is disposed on the turbine housing 343 and spaced apart circumferentially along the turbine housing 343. When the switching tool 3 reaches its downward position, both ends of the pointed limiting boss 41 fit into the limiting groove 42, allowing the switching tool 3 and the outer casing 1 to be precisely limited in both the circumferential and axial directions, ensuring reliable positioning of the switching tool 3. In other embodiments, the structural form of the limiting component 4 only needs to ensure reliable limiting between the outer casing 1 and the switching tool 3.

[0040] In this embodiment, sensor 5 is located at both ends of the pointed-corner limiting boss 41. When the pointed-corner limiting boss 41 and the limiting groove 42 are engaged, sensor 5 is pressed and generates a sensing signal, which is sent to the control section 342 of the drive control unit 34 to realize the upward movement of the switching tool 3. In this embodiment, sensor 5 is a pressure sensor.

[0041] like Figure 8 As shown, the limiting groove 42 includes a flared mating section 421 and a straight clearance section 422 that are interconnected. A pointed limiting boss 41 engages with the flared mating section 421, and the pointed corner of the pointed limiting boss 41 extends into the straight clearance section 422. The circumferential width of the pointed limiting boss 41 is smaller than the width of the straight clearance section 422, and the inner diameter of the limiting groove 42 is smaller than the outer diameter of the pointed limiting boss 41, thereby ensuring that the switching tool 3 will not pass through the limiting groove 42, thus enabling precise positioning of the switching tool 3.

[0042] Furthermore, such as Figure 4 and Figure 5 As shown, the outer surface of the limiting drive block 32 is provided with an upper boss 321, and both the upper and lower end faces of the upper boss 321 are extruded inclined surfaces 323; as Figures 1 to 3As shown, the upper part of the outer sleeve 1 is provided with a mating inclined surface 12. When the flow hole 11 is closed and the switching tool 3 continues to move upward, the mating inclined surface 12 abuts against the upper end face of the upper boss 321. At this time, the limiting drive block 32 retracts radially under the action of the mating inclined surface 12, thereby disengaging from the limiting groove 21 of the moving sleeve 2. The switching tool 3 continues to move upward, thus driving the tool back to the wellhead. Its structure is simple, and it enables the rapid and reliable removal of the switching tool 3 after the moving sleeve 2 is closed.

[0043] Furthermore, the outer surface of the limiting drive block 32 is provided with a lower boss 322. The upper end face of the lower boss 322 and the upper end face of the limiting groove 21 are limiting planes 324. When the switching tool 3 moves upward, the limiting planes 324 of the lower boss 322 and the limiting planes 324 of the limiting groove 21 mutually limit and cooperate to provide axial driving force for the moving sleeve 2; the lower end face of the lower boss 322 and the lower end face of the limiting groove 21 are extrusion slopes 323 to facilitate the radial retraction of the limiting drive block 32. This invention, through the ingenious combination design of the upper boss 321 and the lower boss 322 in the limiting drive block 32, not only realizes the unobstructed and reliable lowering of the switching tool 3, but also realizes the automatic opening and closing function of the sliding sleeve.

[0044] like Figure 4 and Figure 5 As shown, multiple limit drive blocks 32 are arranged, and the mounting spindle 31 has the same number of mounting slots 311 as the limit drive blocks 32. The multiple limit drive blocks 32 are arranged at intervals along the circumference of the mounting spindle 31. Each end of a limit drive block 32 is radially limited within the mounting slots 311 by a clamping sleeve 35, which is installed at both ends of the mounting spindle 31. This structure is compact and simple, and the clamping sleeves 35 effectively fix the position of the limit drive blocks 32, preventing them from radially moving out, thus ensuring the safe and reliable operation of the sliding sleeve opening and closing function.

[0045] In this embodiment, each limiting drive block 32 is provided with two elastic elements 33. The two elastic elements 33 are pre-pressed into the mounting groove 311, and are arranged along the axial direction of the limiting drive block 32. The position and number of elastic elements 33 ensure reliable radial expansion and contraction of each limiting drive block 32. In other embodiments, the number of elastic elements 33 provided in each limiting drive block 32 can be adjusted according to actual conditions, such as three or four.

[0046] like Figure 7 As shown, the outer sleeve 1 includes an upper connector 13, an outer sleeve body 14, and a lower connector 15 connected in sequence. A limiting component 4 is located at the upper connector 13, and a mating inclined surface 12 is located at the upper connector 13; a flow hole 11 is located at the outer sleeve body 14; and a movable sleeve 2 is axially movable and fitted inside the outer sleeve body 14. Its structure is reasonable and compact, and occupies little space.

[0047] When the flow hole 11 is open, the lower end face of the moving sleeve 2 contacts and limits the upper end face of the lower connector 15. At this time, the upper end face of the moving sleeve 2 is located at the lower part of the flow hole 11, and the flow hole 11 is in the open state. When the moving sleeve 2 moves upward under the drive of the limit drive block 32, it gradually closes the flow hole 11 of the outer body 14. When the switching tool 3 continues to move upward, the abutting mating surface of the limit drive block 32 abuts and engages with the mating inclined surface 12 of the upper connector 13. Under the action of the mating inclined surface 12, the limit drive block 32 retracts radially, thereby disengaging from the limit groove 21 of the moving sleeve 2. The switching tool 3 continues to move upward, which drives the tool back to the wellhead.

[0048] In this embodiment, a sealing element is provided between the outer body 14 and the upper connector 13 and the lower connector 15 to prevent liquid from entering; a plurality of sealing elements are provided between the outer body 14 and the outer casing 1 to achieve sliding sealing.

[0049] In this embodiment, a buoyancy cylinder 36 is provided at the end of the mandrel 31 that is furthest from the drive control unit 34. The buoyancy cylinder 36 has a hollow structure inside. When the switching tool 3 ascends to the vertical well section, the buoyancy cylinder 36 can provide buoyancy and reduce the upward resistance.

[0050] The working process of the automatically opening and closing sliding sleeve assembly of the present invention is as follows:

[0051] 1. Lower the outer sleeve 1 and the movable sleeve 2 into the designed position along with the tubing string, and open the flow hole 11 for production; when it is necessary to close the flow hole 11, put the switching tool 3 into the wellhead. The switching tool 3 is pushed down along the casing / tubing by the bidirectional turbine 341, and the limit drive block 32 is in a retracted state under the action of the casing wall.

[0052] 2. For example Figure 1 As shown, when the switching tool 3 reaches the outer sleeve 1, the pointed limiting boss 41 of the turbine housing 343 engages with the limiting groove 42 of the outer sleeve 1, preventing the switching tool 3 from descending further. Simultaneously, the limiting drive block 32 is positioned within the limiting groove 21 at the upper end of the moving sleeve 2. Due to the engagement between the pointed limiting boss 41 and the limiting groove 42, the pressure on the sensor 5 at the pointed limiting boss 41 increases. At this point, the sensor 5 transmits a sensing signal to the control sub-section 342, which controls the bidirectional turbine 341 to rotate in the opposite direction, thereby driving the switching tool 3 upwards. Figure 2 As shown, the limiting plane 324 of the limiting drive block 32 contacts the limiting plane 324 of the moving sleeve 2, thereby driving the moving sleeve 2 to move upward together and gradually close the flow hole 11, thus realizing the closing of the sliding sleeve.

[0053] 3. For example Figure 3As shown, when the sliding sleeve is closed, the switching tool 3 continues to move upward. The extrusion slope 323 on the upper end face of the limit drive block 32 contacts the extrusion slope 323 on the inner surface of the limit connector. At this time, the limit drive block 32 retracts radially under the action of the mating slope 12, thereby disengaging from the limit groove 21 of the moving sleeve 2. The switching tool 3 continues to move upward, which drives the tool back to the wellhead.

[0054] Although the invention has been described with reference to preferred embodiments, various modifications can be made and components can be replaced with equivalents without departing from the scope of the invention. In particular, the technical features mentioned in the various embodiments can be combined in any manner as long as there is no structural conflict. The invention is not limited to the specific embodiments disclosed herein, but includes all technical solutions falling within the scope of the claims.

Claims

1. An automatically opening and closing sliding sleeve assembly, comprising an outer sleeve with a flow passage, a movable sleeve capable of opening and closing the flow passage, and a switching tool for driving the movable sleeve axially, characterized in that, The switching tool includes a mounting mandrel, a limiting drive block, an elastic element, and a drive control unit for moving the switching tool. The limiting drive block is radially telescopically mounted on the mounting mandrel via the elastic element. The drive control unit is mounted on one end of the mounting mandrel. When the switching tool is lowered to a preset position, the limiting drive block extends into the limiting groove of the moving sleeve and drives the moving sleeve to move under the drive of the drive control unit. It also includes a sensor that generates a sensing signal when the switching tool is lowered into place; the drive control unit includes a bidirectional turbine, a control section and a turbine housing, the two ends of the control section are respectively connected to the bidirectional turbine and the mounting mandrel, the turbine housing is located at the head end of the bidirectional turbine, the control section is controlled by the sensor, and the control section receives the sensing signal from the sensor and controls the rotation direction of the bidirectional turbine; A limiting component is provided between the turbine housing and the outer jacket to fix the lowering position of the switch tool, and the sensor is located at the limiting component; The limiting component includes a pointed limiting boss and limiting grooves adapted to both sides of the pointed limiting boss. The pointed end of the pointed limiting boss faces the downward direction of the switching tool. The limiting groove includes a flared mating section and a straight clearance section that are interconnected. The sensor is located at both sides of the pointed limiting boss and generates a sensing signal when the pointed limiting boss and the limiting groove are engaged in a limiting fit. The outer surface of the limiting drive block is provided with an upper boss, and the upper and lower end faces of the upper boss are both extrusion slopes. The upper part of the outer sleeve is provided with a mating slope. When the limiting drive block moves upward to the point where the mating slope abuts against the upper end face of the upper boss, it retracts to disengage from the limiting groove of the movable sleeve. The outer surface of the limiting drive block is provided with a lower boss. The upper end face of the lower boss and the upper end face of the limiting groove are limiting planes that mutually limit and cooperate when the moving sleeve moves. The lower end face of the lower boss and the lower end face of the limiting groove are extrusion slopes that facilitate the retraction of the limiting drive block.

2. The automatically opening and closing sliding sleeve assembly according to claim 1, characterized in that, The limiting drive blocks are arranged in multiple circumferentially along the mounting mandrel, and the mounting mandrel has the same number of mounting slots as the limiting drive blocks; the two ends of the limiting drive blocks are respectively radially limited in the mounting slots by a clamping sleeve; the clamping sleeve is installed at both ends of the mounting mandrel.

3. The automatically opening and closing sliding sleeve assembly according to claim 2, characterized in that, Each of the aforementioned limiting drive blocks is provided with at least two of the aforementioned elastic elements; the elastic elements are pre-pressed in the mounting groove and arranged along the axial direction of the limiting drive block.

4. The automatically opening and closing sliding sleeve assembly according to any one of claims 1 to 3, characterized in that, The end of the mounting spindle furthest from the drive control unit is provided with a buoyancy cylinder to provide buoyancy and reduce movement resistance.

5. The automatically opening and closing sliding sleeve assembly according to any one of claims 1 to 3, characterized in that, The outer sleeve includes an upper connector, an outer sleeve body, and a lower connector connected in sequence. The flow hole is located in the outer sleeve body, and the movable sleeve is axially movable and fitted inside the outer sleeve body.

Images