Pressure-maintaining sampling device, underwater robot and sampling method

Abstract

The invention discloses a pressure-maintaining sampling device, an underwater robot and a sampling method.The pressure-maintaining sampling device comprises a first sleeve, a second sleeve and a coring assembly, the second sleeve is arranged in the first sleeve, and a first opening is formed in one end of the second sleeve; the coring assembly is movably arranged in the second sleeve and comprises a first end used for sampling, and the first end can be ejected out of the second sleeve through the first opening and can be recycled into the second sleeve through the first opening; the first opening is provided with a first sealing mechanism, and when the first end is retracted into the second sleeve, the first opening is sealed by the first sealing mechanism; a second sealing mechanism is arranged between the coring assembly and the second sleeve, and the second sealing mechanism and the first sealing mechanism seal the second sleeve so that a pressure maintaining cavity can be formed in the second sleeve. Therefore, the pressure of the sample can be maintained after sampling, and the integrity of the sample is improved.

Description

Technical Field

[0001] This application relates to the technical field of marine drilling coring, and particularly relates to a pressure-maintaining sampling device, an underwater robot, and a sampling method. Background Art

[0002] The sampling device used in conjunction with an underwater robot can reach the seabed under the transportation of the underwater robot, and the coring component can obtain seabed core samples for further research or utilization. Since there may be natural gas hydrates or gases in the core, during the recovery process after sampling, as the pressure decreases, there is a risk of decomposition or emission of the hydrates or gases, which is not conducive to maintaining the sample characteristics. Therefore, pressure-maintaining measures need to be taken for the sampling device.

[0003] In related technologies, core sampling can be carried out in several different ways. For example, a sampling tool is used in conjunction with a drilling system. However, due to the rotation of the drill string, there are problems such as the sample being interfered by debris such as cuttings during the sampling process, and it is difficult to achieve a pressure-maintaining effect; or a rotary drilling sampling method is adopted. However, there is a problem of formation disturbance, which is not conducive to pressure-maintaining of the sample. The penetration sampling device can reduce the disturbance problem, but still lacks a good pressure-maintaining means. Summary of the Invention

[0004] To solve at least one of the above technical problems, this application provides a pressure-maintaining sampling device, an underwater robot, and a sampling method, which can maintain the pressure of the sample after sampling. The technical solutions adopted are as follows.

[0005] In a first aspect, this application provides a pressure-maintaining sampling device, including a first sleeve, a second sleeve, and a coring component. The first sleeve is used for fixedly setting on an underwater robot; the second sleeve is arranged inside the first sleeve, and one end of the second sleeve is provided with a first opening; the coring component is movably arranged inside the second sleeve. The coring component includes a first end for sampling, and the first end can be ejected out of the second sleeve through the first opening and can be recovered into the second sleeve through the first opening. The first sleeve is used for fixing the second sleeve when the coring component ejects out of the second sleeve. Wherein, the first opening is provided with a first sealing mechanism. When the first end is recovered into the second sleeve, the first sealing mechanism seals the first opening; a second sealing mechanism is arranged between the coring component and the second sleeve. The second sealing mechanism is arranged on the outer periphery of the coring component far from the first end, or the outer periphery of the coring component and the inner wall of the second sleeve are in contact with each other to form the second sealing mechanism. The second sealing mechanism and the first sealing mechanism seal the second sleeve, so as to form a pressure-maintaining cavity inside the second sleeve.

[0006] In certain embodiments of the first aspect of the present application, the first sealing mechanism includes a plate valve, which is rotatably connected to the inner wall surface of the first opening. When the first end is inserted into the first opening, the outer wall surface of the coring assembly abuts against the plate valve to keep the first opening open. When the first end is recovered into the second sleeve, the plate valve rotates to seal the first opening.

[0007] In certain embodiments of the first aspect of the present application, the second sealing mechanism includes an elastic seal, and the elastic seal is arranged between the outer wall surface of the coring assembly and the inner wall surface of the second sleeve.

[0008] In certain embodiments of the first aspect of the present application, a pressure injection chamber is further provided in the second sleeve, and the pressure injection chamber is located at the end of the pressure maintaining chamber away from the first opening, and the pressure injection chamber is not connected to the pressure maintaining chamber. The second sleeve is provided with a power medium injection port for injecting power medium into the pressure injection chamber.

[0009] In certain embodiments of the first aspect of the present application, the first sleeve includes a third opening and a fourth opening arranged opposite to each other, the end of the second sleeve having the first opening is located in the third opening, and a second limiting step is protruding from the inner wall of the third opening. When the coring assembly is ejected from the second sleeve, the second limiting step is used to limit the movement of the second sleeve along the ejection direction.

[0010] In certain embodiments of the first aspect of the present application, the first sleeve includes a third opening and a fourth opening that are oppositely disposed, an end of the second sleeve having the first opening is located in the third opening, and a limiting pin is provided on an inner wall of the fourth opening, with one end of the limiting pin abutting against an outer circumference of the second sleeve;

[0011] The first end is recovered into the second sleeve, and before the first sealing mechanism closes the first opening, the limit pin is used to limit the movement of the second sleeve along the recovery direction; the limit pin is also used to cut off when the second sleeve leaves the first sleeve along the recovery direction to separate the second sleeve from the first sleeve.

[0012] In a second aspect, the present application provides an underwater robot, comprising a main body and a pressure-maintaining sampling device as provided in the first aspect above, wherein the main body is provided with a sampling channel, the sampling channel is connected to the outside of the underwater robot, and the outer wall of the first sleeve of the pressure-maintaining sampling device is fixed to the inner wall of the sampling channel.

[0013] In certain embodiments of the second aspect of the present application, the main body includes at least two sampling channels and at least two pressure-maintaining sampling devices, and one pressure-maintaining sampling device is provided in each sampling channel.

[0014] In a third aspect, the present application further provides a sampling method, which uses the underwater robot provided in the second aspect to perform sampling, and the sampling method includes:

[0015] Launching an underwater robot, which moves to the first sampling point;

[0016] Sampling is performed using one of the pressure-maintaining sampling devices of the underwater robot;

[0017] Move the underwater robot to the second sampling point;

[0018] Sampling is carried out using another pressure-maintaining sampling device of the underwater robot;

[0019] Recover the underwater robot.

[0020] In a fourth aspect, the present application also provides a sampling method, comprising

[0021] Fill the pressure injection chamber with water until the injection pressure is reached;

[0022] ejecting the coring assembly from the second sleeve so that the first end is inserted into the core;

[0023] Start the lifting assembly and pull the coring assembly along the recovery direction;

[0024] The first end of the coring assembly is recovered into the second sleeve, and the first sealing mechanism seals the first opening;

[0025] The coring assembly continues to move in the recovery direction until the lifting shoulder abuts against the lifting step, and drives the second sleeve to move in the recovery direction;

[0026] The second sleeve is lifted in the recovery direction to be separated from the first sleeve.

[0027] The embodiments of the present application have at least the following beneficial effects: the coring assembly is arranged to move relative to the second sleeve, and when the coring assembly ejects the second sleeve, the coring assembly can penetrate into the core, and the sample can enter the coring assembly to achieve sampling. When the coring assembly is recovered into the second sleeve, the core sample located in the coring assembly can be brought back together to achieve sample recovery. By utilizing the first sealing mechanism and the second sealing mechanism, closure can be achieved at both ends of the second sleeve at the same time, so that the internal space of the second sleeve forms a closed pressure-maintaining cavity, so that after the sample enters the pressure-maintaining cavity and during the recovery process of the sampling device, a certain pressure can be maintained in the pressure-maintaining cavity, for example, the pressure in the pressure-maintaining cavity does not drop or drops within an allowable range, thereby ensuring that the properties of the sample do not change during the recovery process, such as preventing hydrate decomposition or avoiding gas escape, thereby meeting the needs of sampling and research. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] The aspects and advantages described and / or appended in the embodiments of the present application will become obvious and easy to understand in conjunction with the following drawings. It should be noted that the embodiments shown in the following drawings are exemplary and are only used to explain the present application, and should not be construed as a limitation to the present application.

[0029] Figure 1 Schematic structural diagram of the pressure-holding sampling device provided by an embodiment of the present application;

[0030] Figure 2 Schematic diagram of the first opening of the second sleeve in the pressure-holding sampling device provided by an embodiment of the present application in an open state;

[0031] Figure 3 Schematic diagram of the first opening of the second sleeve in the pressure-holding sampling device provided by an embodiment of the present application in a sealed state;

[0032] Figure 4 Schematic structural diagram of the core-taking component of the pressure-holding sampling device provided by an embodiment of the present application;

[0033] Figure 5 Schematic structural diagram of the second sleeve of the pressure-holding sampling device provided by an embodiment of the present application;

[0034] Figure 6 Schematic structural diagram of the first sleeve of the pressure-holding sampling device provided by an embodiment of the present application;

[0035] Figure 7 is Figure 1 Partial enlarged view at A in

[0036] Figure 8 is Figure 1 Partial enlarged view at B in

[0037] Figure 9 Schematic structural diagram of the underwater robot provided by an embodiment of the present application;

[0038] Figure 10 Flowchart of an implementation manner of the sampling method provided by an embodiment of the present application;

[0039] Figure 11 Flowchart of another implementation manner of the sampling method provided by an embodiment of the present application.

[0040] Reference numerals:

[0041] 100, pressure-holding sampling device;

[0042] 10, first sleeve; 11, third opening; 111, second limiting step; 12, fourth opening; 121, limiting pin; 1211, elastic support member; 13, retaining groove;

[0043] 20. Second sleeve; 21. First opening; 211. First sealing mechanism; 212. Bearing seat; 22. Pressure holding cavity; 23. Lifting step; 24. Pressure injection cavity; 25. Power medium injection port; 26. Second opening; 261. Third sealing mechanism; 27. Shearing pin;

[0044] 30. Core sampling assembly; 31. First end; 32. Second sealing mechanism; 33. Lifting shoulder; 34. Second end; 341. Shoulder structure; 35. First limiting step; 36. Core barrel; 361. Core sampling cavity; 37. Annular boss; 371. Drainage pipe; 38. Core sampling tube; 39. Centralizer;

[0045] 40. Lifting assembly; 41. Clamp;

[0046] 200. Underwater robot; 201. Main body; 2011. Sampling channel. Detailed implementation manners

[0047] The following combines Figures 1 to 11 Describe the embodiments of the present application in detail. The examples of the embodiments are shown in the drawings, where the same or similar reference numerals represent the same or similar elements or elements with the same or similar functions from beginning to end. The embodiments described below by referring to the drawings are exemplary and are only used to explain the present application and should not be construed as a limitation to the present application.

[0048] In the description of the present application, it should be understood that if terms such as "center", "middle part", "longitudinal", "transverse", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "axial", "radial", "circumferential", etc. are used to indicate the orientation or positional relationship, it is based on the orientation or positional relationship shown in the drawings. It is only for the convenience of describing the present application and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation. Therefore, it should not be construed as a limitation to the present application. In addition, features defined with "first" and "second" may explicitly or implicitly include one or more of such features. In the description of the present application, unless otherwise specified, the meaning of "multiple" is two or more.

[0049] In the description of the present application, it should be noted that unless otherwise clearly specified and limited, the terms "installation", "connection", and "coupling" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, and it can be the communication inside two components. For those of ordinary skill in the art, the specific meanings of the above terms in the present application can be understood according to specific situations.

[0050] In a first aspect, please refer to Figures 1 to 5 , the present application provides a pressure-holding sampling device 100, which includes a first sleeve 10, a second sleeve 20, and a core sampling component 30. The first sleeve 10 is used to be fixedly arranged on an underwater robot 200. The second sleeve 20 is arranged inside the first sleeve 10. One end of the second sleeve 20 is provided with a first opening 21. The core sampling component 30 is movably arranged inside the second sleeve 20. The core sampling component 30 includes a first end 31 for sampling. The first end 31 can be ejected out of the second sleeve 20 through the first opening 21, and the first end 31 can also be recovered into the second sleeve 20 through the first opening 21. The first sleeve 10 is used to fix the second sleeve 20 when the core sampling component 30 is ejected out of the second sleeve 20. Among them, the first opening 21 is provided with a first sealing mechanism 211. When the first end 31 is recovered into the second sleeve 20, the first sealing mechanism 211 seals the first opening 21. A second sealing mechanism 32 is provided between the core sampling component 30 and the second sleeve 20. The second sealing mechanism 32 is arranged on the outer periphery of the core sampling component 30 far from the first end 31, or the outer periphery of the core sampling component 30 and the inner wall of the second sleeve 20 are in contact with each other to form the second sealing mechanism 32. The second sealing mechanism 32 and the first sealing mechanism 211 seal the second sleeve 20, so as to form a pressure-holding cavity 22 inside the second sleeve 20. The core sampling component 30 moves relative to the second sleeve 20. When the core sampling component 30 is ejected out of the second sleeve 20 along the ejection direction a, the core sampling component 30 can penetrate into the core, and the sample can enter the core sampling component 30 to achieve sampling. When the core sampling component 30 is recovered into the second sleeve 20 along the recovery direction b, the core sample located in the core sampling component 30 can be brought back together to achieve the recovery of the sample. By using the first sealing mechanism 211 and the second sealing mechanism 32, the two ends of the second sleeve 20 can be simultaneously closed, so that the internal space of the second sleeve 20 forms a closed pressure-holding cavity 22, so that after the sample enters the pressure-holding cavity 22 and during the recovery process of the sampling device, it can maintain a certain pressure in the pressure-holding cavity 22, for example, the pressure in the pressure-holding cavity 22 does not drop or drops within an allowable range, so as to ensure that the properties of the sample do not change during the recovery process, for example, the hydrate does not decompose or gas leakage is avoided, so as to meet the requirements of sampling and research.

[0051] In some embodiments, please refer to Figure 2 andFigure 3 The first sealing mechanism 211 includes a plate valve, which is rotatably connected to the inner wall of the first opening 21. When the first end 31 is inserted into the first opening 21, the outer wall of the core removal assembly 30 abuts against the plate valve to keep the first opening 21 open. When the first end 31 is recovered into the second sleeve 20, the plate valve rotates to cover the first opening 21. The rotation of the plate valve can realize the switching between the opening and closing of the first opening 21. When the core removal assembly 30 has not completely entered the second sleeve 20, the plate valve cannot be closed due to the blocking effect of the outer wall of the core removal assembly 30, thereby keeping the first opening 21 open (such as Figure 2 As shown in FIG2 , the coring assembly 30 is facilitated to move in the first opening 21, and the plate valve is prevented from blocking or interfering with the coring assembly 30. When the coring assembly 30 is completely inserted into the second sleeve 20, the plate valve can rotate and fall under the action of its own gravity, thereby closing the first opening 21 and sealing the first opening 21 (as shown in FIG2 ). Figure 3 As shown). For example, the plate valve and the first sealing mechanism 211 can be connected by hinges or hinges. Of course, in other examples, the plate valve can also be installed by means of a sliding rail sliding connection. After the plate valve rotates and falls under the action of its own gravity, it can continue to remain in a closed state under the action of gravity, thereby maintaining the sealed state of the first opening 21. When sampling next time, the plate valve can be opened and the core removal assembly 30 can be re-installed in the second sleeve 20 so that the core removal assembly 30 keeps the plate valve in an open state. Optionally, the second sealing mechanism 32 can be arranged at an end of the second sleeve 20 away from the first opening 21, so that there can be enough space between the second sealing mechanism 32 and the first sealing mechanism 211 to form a pressure-maintaining cavity 22, providing sufficient recovery space for the core removal assembly 30, and ensuring that the core removal assembly 30 is always in the pressure-maintaining cavity 22 after entering the second sleeve 20 and during the process of being lifted relative to the second sleeve 20.

[0052] In some embodiments, the second sealing mechanism 32 includes an elastic seal, which is disposed between the outer wall surface of the coring assembly 30 and the inner wall surface of the second sleeve 20. By using the elastic seal, the sealing effect between the outer wall of the coring assembly 30 and the inner wall of the second sleeve 20 can be improved, thereby enhancing the sealing performance. The elastic seal can be arranged at one end of the second sleeve 20 away from the first opening 21 to achieve the sealing effect at both the upper and lower ends of the second sleeve 20. Compared with the direct sealing between the inner wall of the second sleeve 20 and the outer wall of the coring assembly 30, using an elastic seal to achieve the sealing between the two can reduce the friction between them, thereby reducing the occurrence of wear and improving the reliability and lifespan of the pressure-maintaining sampling device 100. Exemplarily, the elastic seal can be a sealing ring with certain flexibility, such as a silicone rubber ring, a rubber ring, or a sealing ring made of other polymer materials. Of course, in other examples, instead of using an elastic seal, the sealing can also be achieved by the mating effect between the inner wall of the second sleeve 20 and the outer wall of the coring assembly 30.

[0053] In some embodiments, refer to Figure 4 and Figure 5 , a lifting step 23 is convexly provided on the inner wall of the second sleeve 20, and a lifting shoulder 33 is convexly provided on the outer periphery of the coring assembly 30. When the coring assembly 30 moves along the recovery direction, the lifting shoulder 33 abuts against the lifting step 23 to drive the second sleeve 20 to move along the recovery direction to separate from the first sleeve 10. When the lifting shoulder 33 moves to abut against the lifting step 23, the first end 31 completely enters the pressure-maintaining cavity 22. In this way, when the coring assembly 30 is recovered, the coring assembly 30 can be used to simultaneously drive the second sleeve 20 to be recovered. On the one hand, it can ensure that the pressure-maintaining effect is maintained throughout the recovery process of the coring assembly 30. On the other hand, it can also eliminate the need to set up a recovery device for the second sleeve 20. That is, by only using a set of equipment to lift and recover the coring assembly 30, the second sleeve 20 can be lifted and recovered simultaneously with the cooperation of the lifting shoulder 33 and the lifting step 23, thereby simplifying the structural design of the pressure-maintaining sampling device 100 and also simplifying the operation steps during sample recovery, thus improving the reliability and sampling efficiency of the sampling operation.

[0054] It can be understood that when the lifting shoulder 33 moves to abut against the lifting step 23 and the first end 31 completely enters the pressure-maintaining cavity 22, it can be achieved by limiting the setting position of the lifting shoulder 33. Specifically, when the first end 31 of the coring assembly 30 sprays out beyond the second sleeve 20, the lifting shoulder 33 moves in a direction away from the lifting step 23. At this time, the lifting shoulder 33 moves to the farthest point from the lifting step 23. Subsequently, as the coring assembly 30 is recovered, the lifting shoulder 33 gradually approaches the lifting step 23 until it abuts against the lifting step 23. During this recovery process, the moving stroke of the lifting shoulder 33 is H (seeFigure 1 When the first end 31 of the coring assembly 30 extends beyond the second sleeve 20, the length of the portion of the coring assembly 30 extending beyond the first seal is T. Assuming H>T, before the lifting shoulder 33 moves to abut against the lifting step 23, the first end 31 of the coring assembly 30 can be completely retracted into the second sleeve 20 and released from its abutment against the plate valve, allowing the plate valve to close and seal the first opening 21. This ensures that the lifting shoulder 33 cannot move to the position of the lifting step 23 before the plate valve seals the first opening 21, thereby ensuring that the plate valve can promptly seal the first opening 21 before the coring assembly 30 drives the second sleeve 20 away from the first sleeve 10.

[0055] In some embodiments, see Figure 1 and Figure 7 The second sleeve 20 also includes a pressure injection chamber 24, which is located at the end of the pressure-maintaining chamber 22 facing away from the first opening 21. The pressure injection chamber 24 and the pressure-maintaining chamber 22 are not connected to each other. The second sleeve 20 is provided with a motive medium injection port 25 for injecting motive medium into the pressure injection chamber 24. The pressure-maintaining chamber 22 can store a certain amount of motive medium (such as seawater or air). When a certain amount of motive medium is injected, the pressure in the pressure injection chamber 24 reaches the injection pressure, thereby ejecting the coring assembly 30 from the second sleeve 20. The first end 31 of the coring assembly 30 penetrates the core to achieve sampling. The third sealing mechanism 261 can seal the pressure injection chamber 24, thereby ensuring that the pressure can continue to increase during the injection of the motive medium. By separating the pressure-maintaining cavity 22 and the pressure-injecting cavity 24 from each other and arranging the pressure-maintaining cavity 22 and the pressure-injecting cavity 24 adjacent to each other along the axial direction of the second sleeve 20, the space in the second sleeve 20 can be fully and reasonably utilized, making the entire pressure-maintaining sampling device 100 more compact.

[0056] In some embodiments, the pressure-maintaining sampling device 100 further includes a water pump connected to the motive medium injection port 25 for injecting water into the pressure injection chamber 24. The water pump can inject seawater into the pressure injection chamber 24 through the motive medium injection port 25 to ensure that the pressure in the pressure injection chamber 24 can continue to increase.

[0057] In some embodiments, the coring assembly 30 further includes a second end 34 opposite the first end 31. The second sleeve 20 has a second opening 26 at the other end thereof. The second end 34 is movably inserted into the second opening 26. A shoulder structure 341 is protruding from the outer periphery of the portion of the second end 34 located within the second sleeve 20. The surface of the shoulder structure 341 facing the second opening 26 and the inner wall of the second sleeve 20 together form the pressure injection chamber 24. The inner wall of the second opening 26 is also provided with a third sealing mechanism 261, which seals the pressure injection chamber 24. The shoulder structure 341 serves as a point of force for the motive medium to propel the coring assembly 30, increasing the force-bearing area and facilitating the motive medium to push the coring assembly 30 out of the second sleeve 20. The third sealing mechanism 261 ensures that the pressure injection chamber 24 can be smoothly pressurized, preventing leakage during water injection. For example, the third sealing mechanism 261 may be a sealing ring, a gasket, or the like.

[0058] In order to ensure that the pressure injection chamber 24 can be pressurized to a certain extent before reaching the injection pressure, so as to ensure that the core collection assembly 30 can obtain sufficient injection power, in some embodiments, the inner wall of the second sleeve 20 is further provided with a shear pin 27, and one end of the shear pin 27 abuts against the outer wall of the core collection assembly 30. When the pressure injection chamber 24 is injected with power medium, the shear pin 27 is used to maintain the position of the core collection assembly 30 in the second sleeve 20. When the pressure in the pressure injection chamber 24 reaches the injection pressure, the shear pin 27 is cut off to release the core collection assembly 30. The shear pin 27 can hold the coring assembly 30. As the pressure in the pressure injection chamber 24 continues to rise, the coring assembly 30 tends to move in the injection direction. At this point, the shear pin 27 can block the coring assembly 30, allowing the pressure in the pressure injection chamber 24 to continue to increase. When the pressure reaches a sufficiently high level, the movement of the coring assembly 30 relative to the second sleeve 20 reaches a shear force sufficient to shear the shear pin 27, thereby shearing the shear pin 27 and ejecting the coring assembly 30 from the second sleeve 20 to achieve sampling. The provision of the shear pin 27 can improve the pressure holding capacity of the pressure injection chamber 24, thereby increasing the injection pressure and the ejection power of the coring assembly 30, allowing the coring assembly 30 to obtain greater kinetic energy during ejection. It is understood that a shear pin 27 with a matching shear force can be selected based on the injection pressure requirements of the pressure injection chamber 24.

[0059] During the process of the coring assembly 30 ejecting outwards, in order to avoid problems such as the entire coring assembly 30 leaving the second sleeve 20, which may cause difficulties in recovery, in some embodiments, a first limiting step 35 is further protruded on the outer periphery of the coring assembly 30, and a bearing seat 212 is further protruded on the inner wall of the first opening 21. When the first end 31 is ejected through the first opening 21 to the outside of the second sleeve 20, the first limiting step 35 abuts against the bearing seat 212, so that a part of the coring assembly 30 is located inside the second sleeve 20. In this way, through the limiting effect of the bearing seat 212 and the first limiting step 35, a part of the coring assembly 30 can be kept inside the second sleeve 20. That is, the part of the coring assembly 30 ejected outside the second sleeve 20 is used to penetrate the core for sampling, and the other part is kept inside the second sleeve 20, so as to provide a guiding effect through the part kept inside the second sleeve 20 during the recovery process of the coring assembly 30, facilitating the further recovery of the entire coring assembly 30 into the second sleeve 20. At the same time, the part of the coring assembly 30 located in the second sleeve 20 can also be used to abut against the plate valve to prevent the plate valve from rotating and falling, so as to keep the first opening 21 open before the entire coring assembly 30 is completely recovered. Exemplarily, the bearing seat 212 and the plate valve can be arranged adjacent to each other along the axial direction of the second sleeve 20, and the plate valve is arranged on the side of the bearing seat 212 away from the opening. The bearing seat 212 can be an annular boss 37 protruded on the inner wall surface of the first opening 21, or several discontinuous bosses arranged circumferentially along the first opening 21. Along the radial direction of the second sleeve 20, the inner diameter of the bearing seat 212 is smaller than the outer diameter of the first limiting step 35, so as to achieve the blocking effect on the first limiting step 35.

[0060] It can be understood that to ensure good sealing performance between the core-taking component 30 and the second sleeve 20, whether it is sealed by an elastic seal or by a tight fit between the core-taking component 30 and the second sleeve 20, there will be a certain frictional force between the two. Due to the existence of the frictional force, during the movement of the core-taking component 30 in the injection direction or the recovery direction, this may cause the second sleeve 20 to also move in the injection direction or the recovery direction under the driving effect of the core-taking component 30, resulting in the second sleeve 20 being disengaged from the first sleeve 10. The first sleeve 10 can provide a fixing and limiting function for the second sleeve 20. During the process of the core-taking component 30 spraying or being completely recovered into the second sleeve 20, the first sleeve 10 can keep the second sleeve 20 from moving, thereby ensuring that a relative movement can occur smoothly between the injection component and the second sleeve 20. Therefore, if the second sleeve 20 is disengaged from the first sleeve 10, this will cause the core-taking component 30 to be unable to be completely recovered into the second sleeve 20, which will also cause the second sleeve 20 to be unable to achieve the function of sealing and maintaining pressure at both ends. Or before the first sealing mechanism 211 closes the first opening 21, if the second sleeve 20 also moves in the recovery direction following the core-taking component 30, the first sleeve 10 will be unable to provide a fixing function for the second sleeve 20, the core-taking component 30 will be unable to be completely recovered into the second sleeve 20, and the first sealing mechanism 211 will also be unable to achieve sealing. To solve the above problems, the present embodiment provides the following two measures.

[0061] In some embodiments, please refer to Figure 1 、 Figure 6 and Figure 7 , the first sleeve 10 includes a third opening 11 and a fourth opening 12 arranged oppositely. One end of the second sleeve 20 with the first opening 21 is located in the third opening 11. A second limiting step 111 is convexly provided on the inner wall of the third opening 11. When the core-taking component 30 sprays from the second sleeve 20, the second limiting step 111 is used to limit the movement of the second sleeve 20 in the injection direction. Through the limiting effect of the second limiting step 111, a blocking effect can be provided for the second sleeve 20 to prevent the second sleeve 20 from moving in the injection direction, so as to ensure that the second sleeve 20 can have good stability during the spraying process of the core-taking component 30, so that the core-taking component 30 can smoothly enter the second sleeve 20 completely during recovery.

[0062] In some embodiments, a limiting pin 121 is provided on the inner wall of the fourth opening 12. One end of the limiting pin 121 abuts against the outer periphery of the second sleeve 20. Before the first end 31 is retracted into the second sleeve 20 and the first sealing mechanism 211 closes the first opening 21, the limiting pin 121 is used to restrict the movement of the second sleeve 20 in the retraction direction. The limiting pin 121 is also used to be cut off when the second sleeve 20 moves away from the first sleeve 10 in the retraction direction, so that the second sleeve 20 is separated from the first sleeve 10. By using the limiting pin 121, a blocking effect can be provided for the movement of the second sleeve 20 in the retraction direction. Before the limiting pin 121 is cut off by the shearing force, the limiting effect can be maintained for a period of time. At this time, it can be ensured that the first end 31 of the core-taking component 30 is completely retracted into the second sleeve 20, avoiding the situation that the second sleeve 20 moves in the retraction direction and disengages from the first sleeve 10 under the driving force of the friction of the core-taking component 30 before the plate valve covers and seals the first opening 21. The core-taking component 30 continues to move in the retraction direction under the lifting action until the first sealing mechanism 211 seals the first opening 21. Then, the lifting shoulder 33 abuts against the lifting step 23. At this time, the core-taking component 30 continues to be lifted and transmits the lifting power to the second sleeve 20 through the lifting shoulder 33. The lifting force at this time can cut off the limiting pin 121 to release the second sleeve 20 and separate it from the first sleeve 10. By providing the limiting pin 121, the limiting effect of the first sleeve 10 on the second sleeve 20 can be realized, and the second sleeve 20 can be released at an appropriate time.

[0063] In some embodiments, an elastic support member 1211 is further provided at one end of the limiting pin 121 for abutting against the second sleeve 20. The elastic support member 1211 abuts against the outer periphery of the second sleeve 20 to provide a squeezing force in the radial direction of the second sleeve 20. A retaining groove 13 is provided on the inner wall of the first sleeve 10, and at least a part of the limiting pin 121 is disposed in the retaining groove 13. By using the elastic support member 1211, the limiting effect of the limiting pin 121 on the second sleeve 20 can be further increased. For example, a plurality of limiting pins 121 are arranged along the circumferential direction of the second sleeve 20. Correspondingly, the elastic support member 1211 is provided at the end of each limiting pin 121. In this way, the plurality of elastic support members 1211 have a clamping effect on the second sleeve 20, avoiding relative movement in the axial direction between the second sleeve 20 and the first sleeve 10 before the first sealing mechanism 211 seals the first opening 21. Exemplarily, the elastic support member 1211 can be a spring. On this basis, by providing the retaining groove 13 and disposing at least a part of the limiting pin 121 in the retaining groove 13, the inner wall surface of the retaining groove 13 can support the limiting pin 121, thereby enhancing the limiting effect of the limiting pin 121.

[0064] In some embodiments, the pressure-maintaining sampling device 100 further includes a lifting assembly 40, which includes a drive member (not shown), a transmission member (not shown), and a clamp 41. The transmission member connects the coring assembly 30 and the drive member, and the drive member is used to drive the transmission member to drive the coring assembly 30 to move in the recovery direction. The clamp 41 is disposed in the recovery path of the coring assembly 30 and is used to clamp the coring assembly 30 when at least a portion of the second sleeve 20 is separated from the first sleeve 10. The drive member can provide power for the recovery and lifting of the coring assembly 30. For example, the drive member can be a power device such as a cylinder or a motor. The transmission member can be a flexible rotating device such as a soft rope, chain, or belt. When the coring assembly 30 is lifted to a certain height, the clamp 41 is used to clamp the coring assembly 30. This can improve the reliability of the clamping, prevent the coring assembly 30 from swaying or rotating, and improve the lifting efficiency.

[0065] In some embodiments, the coring assembly 30 includes a core barrel 36, the interior of which forms a coring cavity 361 for sampling. An annular boss 37 is further provided on the outer periphery of the coring assembly 30. A first limiting step 35 is formed on the side of the annular boss 37 facing the first opening 21, and a lifting shoulder 33 is formed on the side of the annular boss 37 facing away from the first opening 21. A drainage pipe 371 is further provided between the first limiting step 35 and the lifting shoulder 33, and the drainage pipe 371 is connected to the coring cavity 361. The annular boss 37 can simultaneously realize the provision of the first limiting step 35 and the lifting shoulder 33, simplifying the structural design of the coring assembly 30 and making the structure of the coring assembly 30 more compact. By setting up the drainage pipe 371, the seawater remaining in the coring cavity 361 before the coring assembly 30 penetrates into the core can be discharged through the drainage pipe 371. As the core tube 36 penetrates into the core, the core sample material gradually enters the coring cavity 361 and squeezes the seawater in the coring cavity 361 to flow out of the drainage pipe 371.

[0066] In some embodiments, the coring assembly 30 further includes a coring tube 38, which is sleeved around the outer periphery of the core barrel 36. The coring tube 38 protects the core barrel 36 during installation and transportation. For example, the core barrel 36 can be a metal tube, and the coring tube 38 can be a non-metallic tube, such as a transparent PVC tube, to facilitate removal, replacement, or cleaning.

[0067] To ensure smooth relative axial movement between the coring assembly 30 and the second sleeve 20 and provide sufficient space for setting elastic seals, lifting shoulders 33, first limiters, etc., there is a certain gap between the outer wall of the coring assembly 30 and the second sleeve 20. Also, since the coring assembly 30 and the second sleeve 20 are usually arranged as slender tubular structures, during the high-speed injection process of the coring assembly 30, the existence of the above gap easily causes the coring assembly 30 to be eccentric within the second sleeve 20, which is not conducive to the stable operation of the coring assembly 30. Therefore, in some embodiments, a centralizing ring 39 is further convexly provided on the outer periphery of the coring assembly 30. The centralizing ring 39 is used to keep the coring assembly 30 and the second sleeve 20 coaxially arranged when the coring assembly 30 moves within the second sleeve 20. By using the centralizing ring 39, the gap between the outer periphery of the coring assembly 30 and the inner wall of the second sleeve 20 can be reduced, ensuring that the coring assembly 30 and the second sleeve 20 remain coaxially arranged during the ejection process, and improving the accuracy of the movement trajectory and the reliability of use of the coring assembly 30 during injection. Optionally, multiple centralizing rings 39 can be provided, and the multiple centralizing rings 39 are arranged at intervals along the axial direction of the coring assembly 30, thereby further improving the centralizing effect on the coring assembly 30.

[0068] In a second aspect, please refer to Figure 9 , the present application further provides an underwater robot 200, including a main body 201 and a pressure-maintaining sampling device 100 provided as described in the first aspect above. The main body 201 is provided with a sampling channel 2011, and the sampling channel 2011 communicates with the outside of the underwater robot 200. The outer wall of the first sleeve 10 of the pressure-maintaining sampling device 100 is fixed to the inner wall of the sampling channel 2011. In this way, it can be ensured that the first sleeve 10 remains fixed during the entire sampling process, whether it is the injection or recovery process of the coring assembly 30, ensuring the smooth progress of the sampling and recovery processes.

[0069] To improve the sampling efficiency and sampling diversity, in some embodiments, the main body 201 can be provided with at least two sampling channels 2011 and at least two pressure-maintaining sampling devices 100, such as two, three or more, and one pressure-maintaining sampling device 100 is provided in each sampling channel 2011. In this way, the underwater robot 200 can use one pressure-maintaining sampling device 100 to sample at one sampling point. After sampling, it can continue to travel to the next sampling point, such as the second sampling point. At this time, another pressure-maintaining sampling device 100 can be used to sample. In this way, the underwater robot 200 can complete sampling at multiple sampling points during a single diving operation. The underwater robot 200 can meet the requirements of multi-point sampling without multiple dives and recoveries, improving the sampling efficiency.

[0070] Optionally, the water pump can be connected to multiple pressure-maintaining sampling devices 100 through multiple pipelines at the same time, and control valves can be set in the multiple pipelines to individually control the opening or closing of each pipeline to ensure that each pressure-maintaining sampling device 100 can operate independently without affecting each other.

[0071] Thirdly, please refer to Figure 10 , the present application also provides a sampling method, comprising the following steps:

[0072] S1. Inject water into the pressure injection chamber until the injection pressure is reached;

[0073] S2. The coring assembly is ejected from the second sleeve so that the first end is inserted into the core;

[0074] S3. Start the lifting assembly and pull the coring assembly along the recovery direction;

[0075] S4. The first end of the coring assembly is recovered into the second sleeve, and the first sealing mechanism seals the first opening;

[0076] S5. The coring assembly continues to move in the recovery direction until the lifting shoulder abuts against the lifting step, and drives the second sleeve to move in the recovery direction;

[0077] S6. The second sleeve is lifted along the recovery direction to separate from the first sleeve.

[0078] After the first end 31 completely enters the second sleeve 20, the sealing effect of the first sealing mechanism 211 is utilized, and the sealing effect of the second sealing mechanism 32 throughout the entire process is coordinated to form a pressure-maintaining cavity 22 in the second sleeve 20, thereby achieving a pressure-maintaining effect during the sampling process.

[0079] In some embodiments, before the above step S2, the sampling method further includes:

[0080] S21. The shear pin is cut off, releasing the coring assembly.

[0081] The shear pin 27 blocks the coring assembly 30, thereby increasing the pressure holding effect of the pressure injection chamber 24 and thereby enhancing the ejection power of the coring assembly 30. When the pressure in the pressure injection chamber 24 reaches the shear force of the shear pin 27, the shear pin 27 releases the coring assembly 30 to eject, thereby achieving sampling.

[0082] In some embodiments, the above step S6 further includes:

[0083] S61. The second sleeve is lifted in the recovery direction, the limit pin is cut off, and the second sleeve is separated from the first sleeve.

[0084] The blocking effect of the limit pin 121 can prevent relative movement between the second sleeve 20 and the first sleeve 10 before the first sealing mechanism 211 seals the first opening 21, and the limit pin 121 is cut off in time after the lifting shoulder 33 of the sampling component drives the lifting step 23 of the second sleeve 20 to lift, so as to release the second sleeve 20.

[0085] In some embodiments, the above step S6 further includes:

[0086] S61. When the second sleeve is lifted in the recovery direction until at least a part of the second sleeve is separated from the first sleeve, the clamp holds the coring component.

[0087] In this way, using the clamp 41 to hold the coring component 30 in time can reduce the problems of shaking and offset of the coring component 30 during the recovery process, and improve the stability and reliability of the recovery process of the coring component 30.

[0088] It can be understood that the recovery process of the coring component 30 can be divided into two stages. The first stage is to recover the entire coring component 30 into the second sleeve 20 so that the first sealing mechanism 211 closes and seals the first opening 21. The second stage is to continue to lift the coring component 30 so that the lifting shoulder 33 of the coring component 30 abuts against the lifting step 23 of the second sleeve 20 and drives the second sleeve 20 to move in the recovery direction, so that the second sleeve 20 is separated from the first sleeve 10, thus completing the entire recovery process. The recovery processes of the first stage and the second stage can be carried out continuously.

[0089] In some embodiments, please refer to Figure 11 , for the underwater robot equipped with multiple pressure-maintaining sampling devices provided in the above second aspect, its sampling method includes

[0090] S10. Deploy the underwater robot, and the underwater robot moves to the first sampling point;

[0091] S20. Use one of the pressure-maintaining sampling devices of the underwater robot to take a sample;

[0092] S30. Move the underwater robot to the second sampling point;

[0093] S40. Use another pressure-maintaining sampling device of the underwater robot to sample;

[0094] S50. Recover the underwater robot.

[0095] By sampling through the above steps, the effect of multi-point sampling during a single dive of the underwater robot 200 can be achieved. The underwater robot 200 can use a pressure-maintaining sampling device 100 to sample at the first sampling point. After sampling, it can continue to travel to the second sampling point, and at this time, another pressure-maintaining sampling device 100 can be used for sampling. In this way, the underwater robot 200 can complete sampling at multiple sampling points during a single dive operation. The underwater robot 200 can meet the multi-point sampling requirements without multiple dives and recoveries, thus improving the sampling efficiency.

[0096] The following is an example of the working process of the pressure-maintaining sampling device:

[0097] Assemble the pressure-holding sampling device 100 such that the coring assembly 30 is located within the second sleeve 20, and the plate valve at the first opening 21 of the second sleeve 20 is in the open state. The plate valve abuts against the outer periphery of the coring assembly 30 to maintain the opening state of the first opening 21. Lower the underwater robot 200 to the target position, start the water pump, and inject seawater into the pressure injection chamber 24 to gradually increase the water pressure in the pressure injection chamber 24 until it reaches a pressure capable of shearing the shear pin 27. For example, the designed injection pressure is 6 Mpa. At this time, the water pressure shears the shear pin 27, ejecting the first end 31 of the coring assembly 30 out of the second sleeve 20. The first end 31 penetrates into the core, and the core material enters the coring chamber 361 of the core tube 36 of the coring assembly 30, and squeezes the seawater in the coring chamber 361 out through the drainage pipe 371. The coring assembly 30 completes the sampling. The coring assembly 30 uses the first limiting step 35 to abut against the bearing seat 212 of the second sleeve 20, so that a part of the coring assembly 30 remains within the second sleeve 20. The end of the second sleeve 20 with the first opening 21 abuts against the second limiting step 111 of the first sleeve 10 to prevent the second sleeve 20 from leaving the first sleeve 10. After the coring assembly 30 is ejected, turn off the water pump and stop injecting water. After sampling is completed, start to recover the coring assembly 30. The driving part (oil cylinder) of the lifting assembly 40 is activated to drive the transmission part (soft rope) to lift the coring assembly 30. When the first end 31 of the coring assembly 30 completely enters the second sleeve 20, the first sealing structure closes and seals the first opening 21, and the coring assembly 30 completes the first-stage recovery. Continue to lift the coring assembly 30. The coring assembly 30 enters the second-stage recovery. During the lifting process of the coring assembly 30, the lifting shoulder 33 approaches the lifting step 23 of the second sleeve 20 until they abut against each other. The lifting force is transmitted to the second sleeve 20 through the lifting shoulder 33, driving the second sleeve 20 to move relative to the first sleeve 10 in the recovery direction. At the same time, the lifting force acting on the second sleeve 20 shears the limit pin 121, and the limit pin 121 releases the second sleeve 20, enabling the second sleeve 20 to separate from the first sleeve 10, completing the second-stage recovery of the coring assembly 30. Recover the second sleeve 20 and the coring assembly 30 into the interior of the underwater robot 200 to complete the entire sampling process.

[0098] The following is an example of the process of deploying and recovering an underwater robot:

[0099] Drive the sampling vessel to the target station in sea states within sea state 4, turn on the dynamic positioning system, and start operations after the vessel stabilizes. Lower the underwater robot 200 equipped with the pressure-maintaining sampling device 100 into the water. The operators respectively tighten the main anti-sway ropes on both sides of the underwater robot 200, start the winch, pause the winch when the underwater robot 200 is half-submerged, and completely loosen and retrieve the main anti-sway ropes. The control room controls the start of the pump station, and the underwater robot 200 starts automatic orientation. After the orientation of the underwater robot 200 stabilizes, the winch continues to pay out the cable. When the winch pays out the cable to 50 meters, the cable of the underwater robot 200 is tightened, and the underwater robot 200 starts to dive. After the underwater robot 200 dives to the target position and touches the bottom, turn on the water pump and inject water into the pressure injection chamber 24 of the pressure-maintaining sampling device 100. Subsequently, after the pressure-maintaining sampling device 100 completes the entire sampling and recovery process in the above example, the pressure-maintaining sampling device 100 completes the sampling task and starts to recover the underwater robot 200. The winch retrieves the cable. When the underwater robot 200 is recovered to the last 500 meters, closely monitor the underwater positioning information of the underwater robot 200, keep the direction in the stern direction of the vessel, and slightly push the underwater robot 200 forward to ensure that the underwater robot 200 is in the position behind the vessel; when the underwater robot 200 is recovered to 200 meters, the operators on the rear deck standby and pay attention to the cable arrangement position of the cable of the underwater robot 200 to confirm that the underwater robot 200 does not drill under the bottom of the vessel; when the underwater robot 200 is recovered to 100 meters, notify to switch to the control by the rear deck. After turning on the automatic orientation of the underwater robot 200, closely monitor the positioning information of the underwater robot 200. During the cable retrieval process, ensure that the underwater robot 200 remains in the stern direction of the vessel. If the direction deviates, the winch pauses the cable retrieval; when the underwater robot 200 is recovered to 50 meters, after confirming that the position of the underwater robot 200 in the stern is safe, control the underwater robot 200 to float up and slightly pull the underwater robot 200 forward. After the underwater robot 200 surfaces, the winch slowly retrieves the cable to complete the recovery operation of the underwater robot 200.

[0100] In the description of this specification, if there are descriptions of reference terms such as "one embodiment", "some examples", "some embodiments", "schematic embodiments", "examples", "specific examples", or "some examples", it means that the specific features, structures, materials, or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of this application. In this specification, the schematic expressions of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described can be combined in a suitable manner in any one or more embodiments or examples.

[0101] The embodiments of the present application have been described in detail in conjunction with the accompanying drawings. However, the present application is not limited to the above embodiments, and various changes can be made without departing from the gist of the present application within the scope of knowledge possessed by those of ordinary skill in the art.

[0102] In the description of the present application, if the patent name appears with a comma (,), it indicates an "and" relationship rather than an "or" relationship. For example, if the patent name is "a kind of A, B", it means that the content claimed by the present application is: the technical solution with the subject name A and the technical solution with the subject name B.

Claims

1. A pressure-maintaining sampling device, characterized in that: include A first sleeve is used for being fixedly mounted on the underwater robot; a second sleeve, disposed in the first sleeve, wherein one end of the second sleeve is provided with a first opening; a coring assembly movably disposed in the second sleeve, the coring assembly comprising a first end for sampling, the first end being ejected out of the second sleeve through the first opening, the first end being retracted into the second sleeve through the first opening, the first sleeve being used to secure the second sleeve when the coring assembly ejects the second sleeve; In which, the first opening is provided with a first sealing mechanism, and when the first end is recovered into the second sleeve, the first sealing mechanism seals the first opening; a second sealing mechanism is provided between the coring assembly and the second sleeve, and the second sealing mechanism is arranged on the outer periphery of the coring assembly away from the first end, or the outer periphery of the coring assembly and the inner wall of the second sleeve contact each other to form the second sealing mechanism, and the second sealing mechanism and the first sealing mechanism seal the second sleeve to form a pressure-maintaining cavity in the second sleeve.

2. The pressure-maintaining sampling device according to claim 1, characterized in that: The first sealing mechanism includes a plate valve, which is rotatably connected to the inner wall surface of the first opening. When the first end is inserted into the first opening, the outer wall surface of the coring assembly abuts against the plate valve to keep the first opening open. When the first end is recovered into the second sleeve, the plate valve rotates to seal the first opening.

3. The pressure-maintaining sampling device according to claim 1, characterized in that: The second sealing mechanism includes an elastic sealing member, which is arranged between the outer wall surface of the coring assembly and the inner wall surface of the second sleeve.

4. The pressure-maintaining sampling device according to claim 1, characterized in that: A pressure injection chamber is also provided in the second sleeve. The pressure injection chamber is located at the end of the pressure maintaining chamber away from the first opening, and the pressure injection chamber and the pressure maintaining chamber are not connected to each other. The second sleeve is provided with a power medium injection port for injecting power medium into the pressure injection chamber.

5. The pressure-maintaining sampling device according to claim 1, characterized in that: The first sleeve includes a third opening and a fourth opening arranged opposite to each other. The end of the second sleeve having the first opening is located in the third opening. A second limiting step is protruded from the inner wall of the third opening. When the coring assembly is ejected from the second sleeve, the second limiting step is used to limit the movement of the second sleeve along the ejection direction.

6. The pressure-maintaining sampling device according to claim 1, characterized in that: The first sleeve includes a third opening and a fourth opening that are arranged opposite to each other. The end of the second sleeve with the first opening is located in the third opening. The inner wall of the fourth opening is provided with a limit pin, and one end of the limit pin abuts against the outer periphery of the second sleeve. Before the first end is recovered into the second sleeve and the first sealing mechanism closes the first opening, the limit pin is used to limit the movement of the second sleeve along the recovery direction. The limit pin is also used to cut off when the second sleeve leaves the first sleeve along the recovery direction to separate the second sleeve from the first sleeve.

7. An underwater robot, characterized in that: It comprises a main body and a pressure-maintaining sampling device according to any one of claims 1 to 6, wherein the main body is provided with a sampling channel, the sampling channel is connected to the outside of the underwater robot, and the outer wall of the first sleeve of the pressure-maintaining sampling device is fixed to the inner wall of the sampling channel.

8. The underwater robot according to claim 7, characterized in that: The main body includes at least two sampling channels and at least two pressure-maintaining sampling devices, and one pressure-maintaining sampling device is provided in each sampling channel.

9. A sampling method, characterized in that: The underwater robot according to claim 8 is used for sampling, and the sampling method includes: Launching an underwater robot, which moves to the first sampling point; Sampling is performed using one of the pressure-maintaining sampling devices of the underwater robot; Move the underwater robot to the second sampling point; Sampling is carried out using another pressure-maintaining sampling device of the underwater robot; Recover the underwater robot.

10. A sampling method, characterized in that: include Fill the pressure injection chamber with water until the injection pressure is reached; The coring assembly is ejected from the second sleeve so that the first end is inserted into the core; Start the lifting assembly and pull the coring assembly along the recovery direction; The first end of the coring assembly is recovered into the second sleeve, and the first sealing mechanism seals the first opening; The coring assembly continues to move in the recovery direction until the lifting shoulder abuts against the lifting step, and drives the second sleeve to move in the recovery direction; The second sleeve is lifted in the recovery direction to be separated from the first sleeve.

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