Magnetic suspension sealing anti-explosion sampler

Abstract

The utility model discloses a magnetic suspension sealing anti-explosion sampler which comprises a shell, an opening is formed in the upper end of the shell, a liquid inlet is formed in the lower end of the shell, and a one-way sealing mechanism and a magnetic pressure applying assembly are arranged in the shell; the one-way sealing mechanism can seal the liquid inlet and unseal the liquid inlet, a magnetic pressure bearing part is arranged in the one-way sealing mechanism, and the magnetic pressure applying assembly can continuously apply downward force to the magnetic pressure bearing part, so that the one-way sealing mechanism is quickly reset to seal the liquid inlet. The liquid inlet mode is improved, suspension automatic sealing is achieved through the magnetic force repulsion principle, the driving thrust is stable, the sealing speed is high, the sealing effect is good, and the service life is long.

Description

Technical Field

[0001] The utility model relates to the technical field of oil sampling, in particular to a magnetic levitation sealed explosion-proof sampler. Background Technique

[0002] In the production of gathering and transportation stations and depots, in order to master the crude oil production of each storage tank, a three-stage sampler is required to sample successively at the upper, middle, and lower positions of the oil layer of the storage tank. Through chemical analysis, the crude oil production of the storage tank is calculated, which is a basic task for crude oil inventory measurement.

[0003] The existing sampler has an open-top structure. A plug with a spring clip is placed on the top. When reaching the sampling position, the plug is opened by manually pulling the rope, allowing the medium to be sampled to enter the sampler. This sampling method is too complex to operate and has the following disadvantages: First, there is a risk of sampling failure due to the plug being opened in advance before the sampler reaches the designated position; Second, when reaching the sampling position, the plug cannot be opened due to reasons such as the large extensibility of the sampling rope or the plug being too tight, resulting in no sample being taken, which affects the first-time success rate of sampling; Third, if the plug has poor sealing when lowering the sampler, it is easy for liquids at other heights to enter the sampler, leading to deviations in chemical analysis; Fourth, to overcome the buoyancy of the liquid, the sampler is heavy, making it inconvenient for sampling personnel to carry the sampler onto the storage tank for sampling. All these reasons increase the difficulty of sampling operations and pose difficulties for determining the composition of the medium in the storage tank.

[0004] Publication No.: CN216717919U discloses a detachable three-stage oil sampler. Sampling buckets are provided on the support rod, and three sampling buckets are provided to achieve three-stage stratified sampling; the spacing between the sampling buckets can be adjusted, enabling it to be changed according to the actual situation during sampling, making the hierarchical sampling of oil more reasonable and accurate.

[0005] This utility model has many components for three - stage sampling of petroleum. To complete a stratified sampling once, the sampler needs to be made very large to have enough sampling volume, and the sampler will be very heavy. When sampling, first, the distance between the sampling buckets needs to be adjusted according to the actual situation and requirements to achieve hierarchical sampling. During the operation, the nuts and bolts need to be loosened so that the fixing frame can move. Then, use the fixing frame to change the position of the sampling bucket, so that the bucket lid will be aligned with the sampling bucket. After adjustment, the nuts and bolts need to be tightened, and then the device is inserted into the petroleum for three - stage sampling of petroleum. When sampling, the pull - ring also needs to be pulled so that the insertion rod is pulled out from the jack at the upper end of the support rod. The pull - plate needs to be pulled upward, and the pull - plate drives the pull - rod to lift the bucket lid upward, and the bucket lid opens, and the petroleum enters the sampling bucket. During this process, due to the poor extensibility of the sampling rope, it is difficult to judge whether the bucket lid is opened to complete the sampling. After sampling, the pull - plate needs to be loosened so that the insertion rod is inserted into the jack at the upper end of the support rod again. Even if three - stage stratified sampling is achieved, due to the large number of sealing points, it is impossible to avoid the situation that each layer of samples is contaminated due to poor sealing, and the representativeness of the samples is not accurate enough.

[0006] Publication number: CN215525176U, discloses a new type of three - stage sampler for oil tanks, which adopts double - rope synchronous falling and lifting, one rope has a scale, mainly to determine the accurate sampling position of the sampling bucket, and the other rope falls synchronously with the rope with a scale. When the sampler reaches the established position, the soft cork is opened by lifting the other rope, and the oil sample enters. After it is full, the rope is continued to be lifted, and the sampler port is closed by the sealing ball until it is lifted to the top of the tank.

[0007] When sampling with this utility model, first, the bottom cover at the bottom of the sampler needs to be removed, the sealing ball and the connecting rope are placed into the standard sampling bottle, the sampling bottle is placed into the outer shell, and the sampling bottle is rotated to be clamped with the installation ring, and then the bottom cover is installed through screw - thread connection. When sampling, hold the scale rope by hand and lower the sampler to the specified oil layer level. When the specified level is reached, stop the scale rope and keep it still; then shake the connecting rope to open the soft cork. Due to the double - rope design, it is impossible to avoid the two ropes winding around each other, which may cause the cork to be accidentally opened or unable to be opened. During the operation, due to the dual action of the buoyancy of the medium and the extensibility of the rope, the cork is very difficult to open, and it is difficult to judge whether the sampling is completed. After sampling, the bottom cover still needs to be unscrewed, and the built - in sampling bottle is taken out and placed properly to complete the operation of one oil sample. Then, a new sampling bottle is replaced to complete the sampling of different liquid levels; in this way, to complete three - stage sampling, the outer wall of the sampler needs to be frequently cleaned, and operations such as opening the lid, removing the bottle, installing the bottle, closing the lid, and lowering the sampler for sampling are required each time.

[0008] Publication number: CN219532571U, which discloses a self-cleaning locking pin type three-stage sampler for oil-water storage tanks. The bottle stopper rope and the bottle body rope of the traditional three-stage sampler are integrated into one sampling rope, reducing the phenomenon of sampling failure caused by knotting of the sampling rope during sampling. By using a specific sampling mechanism, the opening and closing processes of the sampling bottle are completed during sampling, avoiding the situation that the medium of other layers is mixed into the sampling bottle during the lifting process of the sample, resulting in inaccurate sampling.

[0009] For the sampling operation of this self-cleaning locking pin type three-stage sampler for oil-water storage tanks, first, the outer shell of the sampler needs to be disassembled, the sampling bottle is placed inside the outer shell, and then the outer shell is installed through threaded connection. During sampling, hold the sampling rope by hand and lower the sampler to the specified oil layer liquid level. When the specified liquid level is reached, shake the sampling rope to open the locking pin to complete the sampling. After judging that the sampling is completed, it is also necessary to instantaneously lift the sampling rope again. Using inertia, the pull rod moves upward. The pull rod mechanism moves to the closing positioning pin and is locked, and the reserved flow channel is closed. Lift the sampling bottle out of the oil-water storage tank, open the copper protection shell, and remove the sampling bottle to complete the sampling work. During operation, due to the combined action of the buoyancy of the medium and the extension force of the rope, it is very difficult to open the locking pin, and it is not easy to judge whether the sampling is completed or the flow channel is closed. After sampling is completed, the outer shell needs to be unscrewed, and the built-in sampling bottle needs to be taken out and placed properly to complete the operation of one oil sample. Then, a new sampling bottle is replaced to complete sampling at different liquid levels. To complete three-stage sampling in this way, the outer shell of the sampler needs to be frequently cleaned each time sampling is carried out. Open the outer shell, remove the bottle, install the bottle, close the outer shell, lower the sampler, shake the sampling rope to open the locking pin to complete sampling, and then shake the sampling rope to close the flow channel and lift the sample.

[0010] In summary, the technical solutions, the technical problems to be solved, and the beneficial effects of the above-disclosed technologies are all different from those of the present utility model. Regarding more technical features, technical problems to be solved, and beneficial effects of the present utility model, there is no technical inspiration in the above-disclosed technical documents. Content of the Utility Model

[0011] Aiming at the above-mentioned defects existing in the prior art, the purpose of the present utility model is to provide a magnetic levitation sealed explosion-proof sampler, which can efficiently solve the problem of accurate, fast, and convenient three-stage sampling through a simple, easy-to-produce, and easy-to-install structure.

[0012] To achieve the above purpose, the present utility model adopts the following technical solutions:

[0013] A magnetic levitation sealed explosion-proof sampler, comprising a housing, the upper end of the housing is open, the lower end of the housing is provided with a liquid inlet, and a one-way sealing mechanism and a magnetic pressure component are arranged in the housing; the one-way sealing mechanism can seal and release the liquid inlet, a magnetic pressure-receiving member is arranged in the one-way sealing mechanism, and the magnetic pressure component can continuously apply a downward force to the magnetic pressure-receiving member to quickly reset the one-way sealing mechanism to seal the liquid inlet.

[0014] Further, the lower end of the inner wall of the housing is connected with a sealing seat, the liquid inlet is arranged at the center of the sealing seat, a support rod is arranged at the upper end of the sealing seat, a support plate is arranged at the top of the support rod, the one-way sealing mechanism is arranged between the liquid inlet and the support plate, and the magnetic pressure component is arranged above the support plate.

[0015] Further, the one-way sealing mechanism comprises a guide frame, a sealing member and a guide rod;

[0016] Specifically, the guide frame is fixedly connected to the lower end face of the support plate, a slideway is arranged at the center of the guide frame, the guide rod is arranged in the slideway, the lower end of the guide rod is fixedly connected with the sealing member, the upper end of the guide rod passes through the guide frame, the upper end of the guide rod passes through the support plate, and a magnetic pressure-receiving member is embedded at the upper end of the guide rod.

[0017] Further, the magnetic pressure component comprises a magnetic pressure member and a suspension frame;

[0018] Specifically, the magnetic pressure member is arranged at the center of the suspension frame, the suspension frame is fixedly connected to the upper end face of the support plate, the magnetic pressure member and the magnetic pressure-receiving member are on the same axis, and the lower end of the magnetic pressure member and the upper end of the magnetic pressure-receiving member repel each other with the same polarity to continuously apply pressure.

[0019] Further, the suspension frame, the support plate, the guide frame and the guide rod are all made of non-magnetic conductive materials.

[0020] Further, both the magnetic pressure member and the magnetic pressure-receiving member are neodymium magnets.

[0021] Further, the upper end of the housing is a reduced-diameter port, at least three hanging ears are arranged on the outer wall of the upper end of the housing, the housing is made of pure copper, and a nano oil-repellent coating is applied to the inner part of the housing.

[0022] Further, the sealing member is made of polytetrafluoroethylene material and a nano oil-repellent coating is applied to the surface.

[0023] In the first embodiment of the present utility model, the lower end face of the sealing member is a sealing surface, a sealing ring is arranged at the liquid inlet of the sealing seat, and sealing is achieved after the sealing surface contacts the sealing ring.

[0024] In the second embodiment of the present utility model, the sealing member is a spherical crown plate, the sealing seat is provided with a spherical crown surface at the liquid inlet for cooperating with the spherical crown plate, and a sealing ring is arranged on the spherical crown surface;

[0025] Specifically, the lower end surface of the sealing member includes an internal drainage surface and an external sealing surface. The sealing surface is in contact with the spherical crown surface for sealing, and the drainage surface is not in contact with the spherical crown surface;

[0026] Specifically, at least three convex ribs are arranged on the drainage surface and are evenly distributed circumferentially. A diversion groove is formed between two adjacent convex ribs, and each convex rib is in an arc strip shape bent along the same rotation direction.

[0027] The present utility model has the following beneficial effects compared with the prior art:

[0028] 1. The present utility model adopts a pure copper material, has strong explosion-proof performance, and at the same time improves the liquid inlet mode. It realizes suspended automatic sealing by using the principle of magnetic repulsion, has stable driving thrust, fast sealing speed, good sealing effect, and long service life.

[0029] 2. The sealing member of the present utility model is in the shape of a spherical crown plate and is coated with a nano oil-repellent coating. The sealing member is designed with a drainage surface, which can make the liquid flow into the liquid in a 360° vortex along the axis of the drainage groove. The liquid inlet and drainage volume is about 300 ml / s, reducing the liquid inlet resistance, accelerating the liquid inlet and drainage speed, and ensuring the sampling accuracy.

[0030] 3. The sealing member and the inner part of the shell of the present utility model are coated with a nano oil-repellent coating, which can effectively avoid the wall hanging phenomenon of the sampled medium and facilitate the cleaning of the sampler. Description of the Drawings

[0031] Figure 1 is a schematic structural diagram of a magnetic levitation sealed explosion-proof sampler of the present utility model;

[0032] Figure 2 is a schematic structural diagram of the sealing member in the present utility model.

[0033] In the figure: 1. Shell; 2. Hanging ear; 3. First magnetic member; 4. Suspension frame; 5. Support plate: 6. Support rod; 7. Guide frame; 8. Sealing seat; 9. Sealing member; 9a. Drainage surface; 9b. Diversion groove; 9c. Convex rib; 10. Liquid inlet; 11. Guide rod; 12. Second magnetic member. Specific Embodiments

[0034] The following will be combined with the drawings in the embodiments of the utility model to clearly and completely describe the technical solutions in the embodiments of the utility model. Obviously, the described embodiments are only part of the embodiments of the utility model, not all of the embodiments. Based on the embodiments in the utility model, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the utility model.

[0035] Embodiment 1:

[0036] See also Figures 1 to 2 The utility model provides a magnetic levitation sealed explosion-proof sampler, including a shell 1, the upper end of the shell 1 is open, the lower end of the shell 1 is provided with a liquid inlet 10, the shell 1 is provided with a one-way sealing mechanism and a magnetic pressure component, the one-way sealing mechanism can seal the liquid inlet 10 and unseal the liquid inlet 10, the one-way sealing mechanism is provided with a magnetic pressure piece 12, the magnetic pressure component can continuously apply a downward force to the magnetic pressure piece 12, so that the one-way sealing mechanism quickly resets the sealed liquid inlet 10.

[0037] A sealing seat 8 is threadedly connected to the lower end of the inner wall of the shell 1, the liquid inlet 10 is arranged at the center of the sealing seat 8, a support rod 6 is arranged at the upper end of the sealing seat 8, a support plate 5 is arranged on the top of the support rod 6, the one-way sealing mechanism is arranged between the liquid inlet 10 and the support plate 5, and the magnetic pressure component is arranged on the upper end surface of the support plate 5.

[0038] The one-way sealing mechanism includes a guide frame 7, a sealing member 9, and a guide rod 11. The guide frame 7 is fixedly connected to the lower end surface of the support plate 5. A slideway is provided at the center of the guide frame 7. The guide rod 11 is provided in the slideway. The lower end of the guide rod 11 is fixedly connected to the sealing member 9. The upper end of the guide rod 11 passes through the guide frame 7. The upper end of the guide rod 11 passes through the support plate 5. A magnetic pressure piece 12 is embedded in the upper end of the guide rod 11.

[0039] The magnetic pressure component includes a magnetic pressure piece 3 and a suspension frame 4. The magnetic pressure piece 3 is arranged at the center of the suspension frame 4. The suspension frame 4 is fixedly connected to the upper end surface of the support plate 5. The magnetic pressure piece 3 and the magnetic pressure piece 12 are on the same axis. The lower end of the magnetic pressure piece 3 and the upper end of the magnetic pressure piece 12 repel each other with the same polarity and continuously apply pressure.

[0040] The suspension frame 4, the support plate 5, the guide frame 7 and the guide rod 11 are all made of non-magnetic conductive materials, such as aluminum, etc., to avoid magnetization affecting the application of repulsive force.

[0041] The lower end surface of the sealing member 9 is a sealing surface, and the sealing seat 8 is provided with a sealing ring at the liquid inlet 10, and sealing is achieved after the sealing surface contacts the sealing ring.

[0042] Among them, at least three support rods 6 are provided. The outer walls of the suspension bracket 4 and the guide bracket 7 are both conical to reduce the resistance to the liquid flow. The suspension bracket 4, the support plate 5, and the guide bracket 7 are integrally formed or connected by bolts. The support rod 6 is connected to the seal seat 8 through a threaded joint and a threaded hole. The support plate 5 is connected to the support rod 6 by bolts. The seal 9 is connected to the guide rod 11 by bolts.

[0043] Among them, the upper end of the housing 1 is a reduced-diameter opening. At least three hanging ears are provided on the upper end of the outer wall of the housing 1 for connecting lifting tools such as suspension ropes for lowering and lifting.

[0044] Preferably, the housing 1, the suspension bracket 4, the support plate 5, the support rod 6, the guide bracket 7, the seal seat 8, and the seal 9 are all made of pure copper material, with strong explosion-proof performance.

[0045] Preferably, the seal 9 is made of polytetrafluoroethylene material and is coated with a nano oil-repellent coating after surface polishing.

[0046] Preferably, the inner wall of the housing 1 is coated with a nano oil-repellent coating, and the outer walls of the suspension bracket 4, the support plate 5, the support rod 6, and the guide bracket 7 are coated with a nano oil-repellent coating.

[0047] Preferably, the magnetic pressure member 3 and the magnetic pressure-receiving member 12 are both neodymium magnets, and the two neodymium magnets have opposite magnetic poles. The suspension and automatic sealing are achieved by the repulsion between the same poles of the magnetic poles.

[0048] Embodiment 2:

[0049] Based on Embodiment 1, this embodiment provides a method for using a magnetic suspension sealed explosion-proof sampler, which specifically includes the following steps:

[0050] Connect the hanging ear 2 with a suspension rope and lower the sampler. Under the action of gravity, the seal moves downward. Under the action of the buoyancy of the liquid flow and the impact of the liquid flow, the seal 9 automatically opens and continuously takes in liquid from the lower part of the sampler and discharges the liquid from the top.

[0051] When the sampler reaches the sampling point, stop lowering the sampler. At this time, the seal 11 rebounds under the repulsive force between the magnetic pressure member 3 and the magnetic pressure-receiving member 12 and abuts against the liquid inlet 10 to achieve sealing. The medium at the sampling point is stored in the sampler. Lift the sampler. During the lifting process, no flow channel can be established between the sampler and the outside world, and only a small amount of diffusion exchange exists at the top opening. After taking it out, first pour out the liquid at the bottle mouth, and then pour the remaining liquid into the sampling bottle to complete the sampling operation.

[0052] Clean and repeat three times, or prepare three samplers to complete three-level sampling. Only two actions of lowering and lifting are required during the sampling process, which is simple and fast.

[0053] Furthermore, a spring door panel is provided at the upper opening of the housing 1. During the lowering process, the door panel is opened by the impact of the liquid flow for liquid passage. After hovering, the door panel resets under the action of the spring, blocking the upper opening of the housing 1 to reduce liquid exchange.

[0054] Embodiment 3:

[0055] Based on Embodiment 1, in this embodiment, the seal 11 is a spherical crown plate, and the seal seat 8 is provided with a spherical crown surface that cooperates with the spherical crown plate at the liquid inlet 10, and a sealing ring is provided on the spherical crown surface.

[0056] The machining accuracy of the seal 11 reaches IT3 level, and the surface roughness Ra is 0.8 - 0.25 μm. The lower end surface of the seal 11 includes an internal drainage surface 9a and an external sealing surface. The sealing surface is in contact with the spherical crown surface for sealing, and the drainage surface 9a is not in contact with the seal seat 8.

[0057] The drainage surface 9a is provided with at least three convex ribs 9c evenly distributed in the circumferential direction. A diversion groove 9b is formed between two adjacent convex ribs 9c. Each convex rib 9c is in the shape of an arc strip bent in the same rotation direction. The diversion groove 9b can enable the liquid flow to enter the liquid along the axis of the diversion groove 9b, accelerating the liquid inlet and drainage speed.

[0058] For the components themselves that are not elaborated in this application and the connection methods of the various components in this application, they all belong to the well-known technologies in the technical field. They can be directly applied and will not be elaborated further.

[0059] In the present utility model, the term "a plurality of" refers to two or more, unless otherwise clearly defined. Terms such as "installation", "connection", "coupling", "fixing" and other terms should be understood in a broad sense. For example, "connection" can be a fixed connection, a detachable connection, or an integral connection; "coupling" can be a direct connection or an indirect connection through an intermediate medium. For those of ordinary skill in the art, the specific meanings of the above terms in the present utility model can be understood according to specific circumstances.

[0060] In the description of the present utility model, it should be understood that the orientation or positional relationship indicated by terms such as "upper", "lower", "left", "right", "front", "rear", etc. is based on the orientation or positional relationship shown in the drawings, and is only for the convenience of describing the present utility model and simplifying the description, rather than indicating or implying that the device or unit referred to must have a specific direction, be constructed and operated in a specific orientation. Therefore, it should not be construed as a limitation to the present utility model.

[0061] In the description of this specification, the descriptions of the terms "one embodiment", "some embodiments", "specific embodiments", etc. mean 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 the present utility model. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner.

[0062] The foregoing is only the preferred embodiment of the present utility model and is not intended to limit the present utility model. For those skilled in the art, the present utility model may have various modifications and changes. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present utility model shall be included within the protection scope of the present utility model.

Claims

1. A magnetic suspension sealed explosion-proof sampler, comprising a shell, the upper end of which is open, characterized in that: A liquid inlet is arranged at the lower end of the shell, and a one-way sealing mechanism and a magnetic pressure component are arranged inside the shell; The one-way sealing mechanism can seal and unseal the liquid inlet. A magnetic pressure piece is provided in the one-way sealing mechanism. The magnetic pressure component can continuously apply downward force to the magnetic pressure piece, so that the one-way sealing mechanism can quickly reset the sealed liquid inlet.

2. A magnetic suspension sealed explosion-proof sampler according to claim 1, characterized in that: A sealing seat is connected to the lower end of the inner wall of the shell, the liquid inlet is arranged at the center of the sealing seat, a support rod is arranged at the upper end of the sealing seat, a support plate is arranged on the top of the support rod, the one-way sealing mechanism is arranged between the liquid inlet and the support plate, and the magnetic pressure assembly is arranged above the support plate.

3. A magnetic suspension sealed explosion-proof sampler according to claim 2, characterized in that: The one-way sealing mechanism comprises a guide frame, a sealing member and a guide rod; The guide frame is fixedly connected to the lower end surface of the support plate, a slideway is arranged at the center of the guide frame, the guide rod is arranged in the slideway, the lower end of the guide rod is fixedly connected to the sealing member, the upper end of the guide rod passes through the guide frame, the upper end of the guide rod passes through the support plate, and a magnetic pressure piece is embedded in the upper end of the guide rod.

4. The magnetic suspension sealed explosion-proof sampler according to claim 3, characterized in that: The magnetic pressure component includes a magnetic pressure piece and a suspension frame; The magnetic pressure piece is arranged at the center of the suspension frame, the suspension frame is fixedly connected to the upper end surface of the support plate, the magnetic pressure piece and the magnetic pressure piece are on the same axis, the lower end of the magnetic pressure piece and the upper end of the magnetic pressure piece repel each other with the same polarity and continuously apply pressure.

5. The magnetic suspension sealed explosion-proof sampler according to claim 4, characterized in that: The suspension frame, support plate, guide frame and guide rod are all made of non-magnetic conductive materials.

6. The magnetic suspension sealed explosion-proof sampler according to claim 4, characterized in that: The magnetic pressure-applying member and the magnetic pressure-receiving member are both neodymium magnets.

7. The magnetic suspension sealed explosion-proof sampler according to claim 1, characterized in that: The upper end of the shell is a reduced diameter opening, the upper end of the outer wall of the shell is provided with at least three hanging ears, the shell is made of pure copper, and the inside of the shell is coated with a nano-oil-repellent coating.

8. The magnetic suspension sealed explosion-proof sampler according to claim 3, characterized in that: The sealing element is made of polytetrafluoroethylene material, and the surface is coated with a nano-oil-repellent coating.

9. The magnetic suspension sealed explosion-proof sampler according to claim 3, characterized in that: The lower end surface of the sealing member is a sealing surface, and the sealing seat is provided with a sealing ring at the liquid inlet, and sealing is achieved after the sealing surface contacts the sealing ring.

10. The magnetic suspension sealed explosion-proof sampler according to claim 3, characterized in that: The sealing member is a spherical crown plate, the sealing seat is provided with a spherical crown surface matching the spherical crown plate at the liquid inlet, and a sealing ring is provided on the spherical crown surface; The lower end surface of the sealing member includes an internal drainage surface and an external sealing surface, wherein the sealing surface contacts and seals with the spherical crown surface, and the drainage surface does not contact with the spherical crown surface; The drainage surface is provided with at least three convex ribs evenly distributed along the circumferential direction, a guide groove is formed between two adjacent convex ribs, and each convex rib is in the shape of an arc strip bent along the same rotation direction.

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