Inlet nozzle adjustment mechanism and spring mounting structure

Abstract

The utility model provides an entrance nozzle adjusting mechanism and spring mounting structure. Entrance nozzle adjusting mechanism is used for turboexpander. Among them, the mounting end of pressure spring is installed in the mounting hole of support disc, and the telescopic end of pressure spring is connected to nozzle cover ring. The entrance nozzle adjusting mechanism further includes a protective cylinder, which is installed in the mounting hole of the support disc. The bottom end of the pressure spring is accommodated in the cylinder hole of the protective cylinder, and there is a gap between the pressure spring and the cylinder hole. The bottom end includes the mounting end. The cylinder hole has a hole bottom, and the mounting end of the pressure spring abuts against the hole bottom. The above-mentioned entrance nozzle adjusting mechanism can reduce maintenance cost.

Description

Technical Field

[0001] This utility model relates to mechanical structures, to an inlet nozzle adjustment mechanism, and more particularly, to a spring mounting structure. Background Technology

[0002] Chinese invention patent CN109983204B discloses an inlet nozzle adjustment mechanism for a turboexpander. A pressure spring is installed between the support disc and the nozzle cover ring. By extending and retracting the pressure spring, the position of the nozzle cover ring can be finely adjusted, thereby maintaining the axial clearance of the inlet nozzle blades.

[0003] In actual use, components such as pressure springs, support plates, and nozzle cover rings are frequently damaged, thus requiring frequent replacement and incurring high maintenance costs.

[0004] Therefore, it is necessary to find a solution to the above problems. Utility Model Content

[0005] The purpose of this invention is to provide an inlet nozzle adjustment mechanism that can reduce maintenance costs.

[0006] A further objective of this invention is to provide an inlet nozzle adjustment mechanism that can reduce the probability of damage.

[0007] Another objective of this invention is to provide a spring mounting structure that can be applied to similar situations where the spring is subject to fluid disturbance, thereby reducing maintenance costs.

[0008] This invention provides an inlet nozzle adjustment mechanism for a turbine expander. The inlet nozzle adjustment mechanism includes a nozzle cover ring, a support plate, and a pressure spring. The mounting end of the pressure spring is installed in a mounting hole in the support plate, and the telescopic end of the pressure spring is connected to the nozzle cover ring. The inlet nozzle adjustment mechanism also includes a protective cylinder, which is installed in the mounting hole of the support plate. The bottom end of the pressure spring is accommodated in a hole in the protective cylinder, with a gap between the pressure spring and the hole. The bottom end includes a mounting end. The hole has a bottom, and the mounting end of the pressure spring abuts against the bottom of the hole.

[0009] In one embodiment, the protective cylinder has a protruding section that extends beyond the surface of the support disc, the surface of the support disc facing the nozzle cover ring.

[0010] In one embodiment, there is a gap between the end face of the protruding cylinder section and the annular surface of the nozzle cover ring, wherein the annular surface of the nozzle cover ring faces the protruding cylinder section, and the gap is 1 to 5 mm. The pressure spring is arranged such that the gap between the pressure spring and the cylinder bore is 1 to 3 mm at any point.

[0011] In one embodiment, the protective sleeve has a threaded rod segment with external threads, and the protective sleeve is adapted to the mounting hole by being threadedly connected to the threaded hole segment of the mounting hole through the threaded rod segment.

[0012] In one embodiment, the mounting hole is a stepped hole. The smaller diameter section of the stepped hole forms a threaded section, which is threadedly connected to the smaller outer diameter threaded rod section of the protective cylinder, while the larger diameter section of the stepped hole is a smooth hole, which is adapted to the larger outer diameter smooth rod section of the protective cylinder.

[0013] In one embodiment, the protective cylinder has a through hole extending through the smooth section of the protective cylinder, while the protective cylinder also has a perforation in the threaded section. The smaller-diameter perforation communicates with the larger-diameter cylinder hole, thereby forming a stepped hole, the stepped surface of which constitutes the bottom of the cylinder hole.

[0014] This utility model provides a spring mounting structure for fluid machinery. The spring mounting structure includes a movable seat, a base, and a pressure spring. Fluid flows around the pressure spring. The mounting end of the pressure spring is installed in a mounting hole in the base, and the telescopic end of the pressure spring is connected to the movable seat. The spring mounting structure also includes a protective cylinder, which is installed in the mounting hole in the base. The bottom end of the pressure spring is accommodated in a hole in the protective cylinder, with a gap between the pressure spring and the hole. The bottom end includes a mounting end. The hole has a bottom, and the mounting end of the pressure spring abuts against the bottom of the hole.

[0015] In one embodiment, the protective cylinder has a protruding section extending beyond the surface of a base, the surface of which faces a movable seat. A gap of 1-5 mm exists between the end face of the protruding section and the surface of the movable seat, wherein the surface of the movable seat faces the protruding section. A pressure spring is arranged such that the gap between the pressure spring and the cylinder bore is 1-3 mm at any point.

[0016] In one embodiment, the protective sleeve has a smooth section with a larger outer diameter and a threaded section with a smaller outer diameter and external threads. The mounting hole is a stepped hole, which includes a small-diameter hole section with internal threads and a large-diameter hole section in the form of a smooth hole. The threaded section of the protective sleeve is threadedly connected to the small-diameter hole section of the mounting hole, and the smooth section of the protective sleeve is adapted to the large-diameter hole section of the mounting hole.

[0017] In one embodiment, the protective cylinder has a through hole extending through the smooth section of the protective cylinder, while the protective cylinder also has a perforation in the threaded section. The smaller-diameter perforation communicates with the larger-diameter cylinder hole, thereby forming a stepped hole, the stepped surface of which constitutes the bottom of the cylinder hole.

[0018] The inventors discovered that the aforementioned damage is primarily caused by the vibration of the pressure spring due to airflow disturbances, leading to wear on the pressure spring and surrounding components. When the aforementioned inlet nozzle adjustment mechanism is used in a turboexpander, by adding a protective sleeve to support the pressure spring on the support plate, when damage occurs to the pressure spring's components, it is no longer necessary to replace the entire support plate; only the protective sleeve needs to be replaced. Therefore, maintenance costs can be significantly reduced.

[0019] Furthermore, by setting the protective cylinder to have a protruding section that protrudes from the support plate, and optimizing the distance between the end face of the protruding section and the annular surface of the nozzle cover ring, as well as the gap between the pressure spring and the cylinder hole, the disturbance of the airflow to the pressure spring can be reduced or even prevented, thereby reducing the probability of damage from the source and avoiding damage.

[0020] Similar to the previous one, the above-described spring mounting structure can be applied to similar situations where the spring is subject to fluid disturbance, reducing maintenance costs. Attached Figure Description

[0021] The advantages and spirit of this utility model can be further understood through the following detailed description and accompanying drawings.

[0022] Figure 1 This is a schematic diagram showing the inlet nozzle adjustment mechanism according to the present invention.

[0023] Figure 2 This is a magnified view of the inlet nozzle adjustment mechanism.

[0024] Figure 3 This is a schematic diagram showing the original inlet nozzle adjustment mechanism. Detailed Implementation

[0025] The specific embodiments of this utility model are described in detail below with reference to the accompanying drawings. However, it should be understood that this utility model is not limited to the embodiments described below, and the technical concept of this utility model can be implemented in combination with other known technologies or functions, or with other technologies that are the same as those known technologies.

[0026] For example, if the first feature described subsequently in the specification is formed above or on the second feature, this can include embodiments where the first and second features are formed by direct connection, or embodiments where an additional feature is formed between the first and second features, so that the first and second features are not directly connected. Furthermore, when the first element is described in a manner connected or combined with the second element, the description includes embodiments where the first and second elements are directly connected or combined with each other, as well as embodiments where one or more other intervening elements are incorporated to indirectly connect or combine the first and second elements with each other.

[0027] It is understood that the terms "first" and "second" are used for descriptive purposes only and do not refer to limitations on chronological order, quantity, or importance. They should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated, but are merely used to distinguish one technical feature from another in this technical solution. Therefore, a feature specified as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this utility model, "multiple" means two or more (i.e., more than two), unless otherwise explicitly specified. Similarly, qualifiers such as "one" appearing in the text do not refer to limitations on quantity, but rather describe technical features not previously mentioned. Likewise, unless a noun is modified by a specific quantifier, the text should be considered to include both singular and plural forms; the technical solution may include either a singular or plural number of that technical feature. Similarly, modifiers such as "approximately" or "about" preceding numerals in the text usually include the number itself, and their specific meaning should be understood in conjunction with the context. In addition, unless otherwise stated, descriptions such as "above", "below", "at least", and "at most" include the corresponding numerical value, while descriptions such as "higher than", "lower than", "more than", and "less than" do not include the corresponding numerical value.

[0028] like Figure 3 As shown, in the inlet nozzle adjustment mechanism 10a of the turboexpander 100a, a pressure spring 3 is provided between the support plate 2a and the nozzle cover ring 1 to maintain the axial clearance of the blades at the inlet nozzle S1. Under normal circumstances, the pressure spring 3 applies a preload to the nozzle cover ring 1, thereby reducing airflow leakage at the inlet nozzle S1.

[0029] Figure 3 The document also shows related components near the inlet nozzle S1, such as the cam follower 5, the nozzle guide vane 6, and the nozzle pivot pin 7. For detailed structure information, please refer to CN109983204B. Figure 3 It can be seen that the support plate 2a, nozzle cover ring 1, etc. are actually disc-shaped or ring-shaped objects that rotate around the central axis O1; the pressure springs 3 can be distributed in multiples along the circumference, and are commonly evenly distributed.

[0030] The inlet nozzle adjustment mechanism 10a frequently fails, requiring replacement of related components. However, replacement costs are high. Therefore, a solution is needed to reduce maintenance costs.

[0031] The inventors analyzed the inlet nozzle adjustment mechanism 10a and concluded that the damage was caused by turbulence in the airflow near the pressure spring 3 due to the presence of the inlet nozzle S1. This turbulence caused the pressure spring 3 to vibrate at high frequency. The vibration of the pressure spring 3 caused wear between it and other components such as the support plate 2a and the nozzle cover ring 1, thus damaging these components.

[0032] Figure 1 The construction of the inlet nozzle adjusting mechanism 10 is illustrated exemplarily. The inlet nozzle adjusting mechanism 10 is used in the turbine expander 100. It is understood that the accompanying drawings are for illustrative purposes only and are not necessarily drawn to scale, and should not be construed as limiting the scope of protection of this invention.

[0033] The inlet nozzle adjusting mechanism 10 includes a nozzle cover ring 1, a support plate 2, and a pressure spring 3. The mounting end 33 of the pressure spring 3 is installed in the mounting hole 21 of the support plate 2. The telescopic end 34 of the pressure spring 3 is connected to the nozzle cover ring 1.

[0034] In the illustrated embodiment, the inlet nozzle adjusting mechanism 10 further includes a protective cylinder 4. The protective cylinder 4 is installed in the mounting hole 21 of the support plate 2. The bottom end 31 of the pressure spring 3 is accommodated in the cylinder hole 41 of the protective cylinder 4. There is a gap g3 between the pressure spring 3 and the cylinder hole 41. The bottom end 31 includes a mounting end 33.

[0035] Combination Figure 2 and Figure 1 The cylindrical hole 41 has a bottom 43. The mounting end 33 of the pressure spring 3 abuts against the bottom 43. Thus, a portion of the pressure spring 3 is housed within the cylindrical hole 41 of the protective cylinder 4, with one end supported by the protective cylinder 4, and thus supported by the support plate 2. As will be mentioned later, the bottom 43 shown in the figure is essentially an annular plane.

[0036] The protective cylinder 4 has a protruding cylindrical section 48 that extends beyond the disc surface 28 of the support plate 2. This disc surface 28 of the support plate 2 faces the nozzle cover ring 1. That is, the protective cylinder 4 not only has an internal cylindrical section housed within the support plate 2, but also a protruding cylindrical section 48 that extends toward the nozzle cover ring 1 and protrudes beyond the support plate 2. In this way, the protruding cylindrical section 48 can block the disturbance of the surrounding airflow to the pressure spring 3, thereby weakening and preventing the vibration of the pressure spring 3.

[0037] A distance s1 exists between the end face 49 of the protruding cylindrical section 48 and the annular surface 18 of the nozzle cover ring 1. The annular surface 18 of the nozzle cover ring 1 faces the protruding cylindrical section 48. The end face 49 of the protruding cylindrical section 48 is also the free end face of the protective cylinder 4. The aforementioned distance s1 is 1~5mm. The aforementioned distance s1 is the axial distance X0 between the end face 49 of the protruding cylindrical section 48 and the annular surface 18 of the nozzle cover ring 1. This distance s1 ensures that the adjustment function of the pressure spring 3 is not affected. Simultaneously, most of the pressure spring 3 (i.e., more than half its length) is housed within the protective cylinder 4, minimizing the impact of airflow on the pressure spring 3.

[0038] The pressure spring 3 is arranged such that the gap g3 between the pressure spring 3 and the cylindrical hole 41 is 1~3mm at any point. The aforementioned gap g3 is also the radial distance R0 between the outer periphery of the pressure spring 3 and the cylindrical wall of the cylindrical hole 41. Preferably, the pressure spring 3 and the protective cylinder 4 are arranged coaxially; therefore, the gap g3 is the difference between the radius of the bore 41 of the protective cylinder 4 and the outer radius of the pressure spring 3. This also balances the influence on the adjustment function of the pressure spring 3 and its protective function.

[0039] Figure 2 An enlarged view of the portion near the protective sleeve 4 is shown as an example. The protective sleeve 4 has a threaded rod segment 47 with external threads. The protective sleeve 4 is adapted to the mounting hole 21 by being threadedly connected to the threaded hole segment 22 of the mounting hole 21 via the threaded rod segment 47. This configuration allows for convenient and reliable installation.

[0040] Mounting hole 21 is a stepped hole. The small-diameter section of this stepped hole forms a threaded hole section 22, which is threadedly connected to the threaded rod section 47 with a smaller outer diameter of the protective cylinder 4. The large-diameter section 23 of this stepped hole is a smooth hole, which is adapted to the smooth rod section 46 with a larger outer diameter of the protective cylinder 4. Figure 1 In the protective cylinder 4, the smooth rod section 46 includes a protruding cylindrical section 48. That is, a portion of the smooth rod section 46 is also located within the support plate 2. This structure facilitates installation.

[0041] The protective cylinder 4 has a through hole 41 that is provided in the smooth rod section 46 of the protective cylinder 4, and the protective cylinder 4 also has a through hole 42 in the threaded rod section 47.

[0042] The smaller perforation 42 connects with the larger cylindrical hole 41, thus forming a stepped hole. The stepped surface of this stepped hole forms the bottom 43 of the cylindrical hole 41. The stepped surface forming the bottom 43 is essentially a hollow annular surface.

[0043] For example, the pressure spring 3 and the protective cylinder 4 can be made of metal. For example, the pressure spring 3 and the protective cylinder 4 can be made of stainless steel. This allows them to withstand low temperatures.

[0044] Figure 1 The diagram also shows that the nozzle cover ring 1 includes a cover plate 1 connected to a pressure spring 3 and a plug 12 extending protruding from the cover plate 1. The plug 12 is inserted into the central hole 25 of the support plate 2, thereby allowing the nozzle cover ring 1 and the support plate 2 to slide together. Figure 1 The diagram also shows that the central disc hole 25 has an enlarged section 26 with a relatively larger diameter at one end near the cover plate 1. The enlarged section 26 can be filled with a sealing ring, thereby achieving a sealing effect.

[0045] The specific structure of the aforementioned inlet nozzle adjusting mechanism 10 can essentially serve as an example of a more general spring-mounted structure 20. The spring-mounted structure 20 is used in fluid machinery. Fluid machinery, for example, is... Figure 1 The turbine expander 100 in the middle.

[0046] The spring mounting structure 20 includes a movable seat (e.g., nozzle cover ring 1), a base (e.g., support plate 2), and a pressure spring 3. Fluid flows around the pressure spring 3. Figure 1 In the turbine expander 100 shown, process gas flows around the pressure spring 3, making it susceptible to vibration due to the flow of the process gas, which can easily cause wear.

[0047] The mounting end 33 of the pressure spring 3 is installed in the mounting hole 21 of the base, and the telescopic end 34 of the pressure spring 3 is connected to the movable seat.

[0048] Similar to the previously mentioned, the spring mounting structure 20 also includes a protective sleeve 4, which is installed in the mounting hole 21 of the base. The bottom end 31 of the pressure spring 3 is accommodated in the cylinder hole 41 of the protective sleeve 4, with a gap g3 between the pressure spring 3 and the cylinder hole 41. The bottom end 31 includes a mounting end 33. The cylinder hole 41 has a bottom 43. The mounting end 33 of the pressure spring 3 abuts against the bottom 43.

[0049] As previously described, the protective cylinder 4 may have a protruding cylindrical section 48 that protrudes from the surface of the base (for example, the disc surface 28 of the support disc 2). The surface of the aforementioned base faces the movable seat.

[0050] There is a gap s1 between the end face 49 of the protruding cylindrical section 48 and the surface of the movable seat (for example, the annular surface 18 of the nozzle cover ring 1). The aforementioned gap s1 can be 1~5mm. The surface of the movable seat faces the protruding cylindrical section 48.

[0051] The pressure spring 3 can be arranged such that the gap g3 between the pressure spring 3 and the cylinder hole 41 is 1~3mm at any point.

[0052] The protective cylinder 4 may have a smooth rod section 46 with a larger outer diameter and a threaded rod section 47 with a smaller outer diameter and external threads. The mounting hole 21 may be a stepped hole, which includes a small-diameter hole section with internal threads (i.e., threaded hole section 22) and a large-diameter hole section 23 in the form of a smooth hole. The threaded rod section 47 of the protective cylinder 4 is threadedly connected to the small-diameter hole section (i.e., threaded hole section 22) of the mounting hole 21, and the smooth rod section 46 of the protective cylinder 4 is adapted to the large-diameter hole section 23 of the mounting hole 21.

[0053] The protective cylinder 4 can have a through hole 41 in the smooth rod section 46 of the protective cylinder 4, and the protective cylinder 4 can also have a through hole 42 in the threaded rod section 47.

[0054] The smaller perforation 42 can connect with the larger cylindrical hole 41, thus forming a stepped hole. The stepped surface of this stepped hole forms the bottom 43 of the cylindrical hole 41.

[0055] The text actually mentions an optimized method for an inlet nozzle adjustment mechanism used in a turbine expander 100. The original inlet nozzle adjustment mechanism 10a can be found, for example, in [reference needed]. Figure 3 This optimization method modifies the original inlet nozzle adjustment mechanism 10a, and therefore can also be called a modification method.

[0056] The original inlet nozzle adjustment mechanism 10a may include a nozzle cover ring 1, a support plate 2, and a pressure spring 3. The mounting end 33 of the pressure spring 3 is installed in the mounting hole 21 of the support plate 2, and the telescopic end 34 of the pressure spring 3 is connected to the nozzle cover ring 1.

[0057] In this optimized method, a protective cylinder 4 is added and installed in the mounting hole 21 of the support plate 2. The bottom end 31 of the pressure spring 3 is accommodated in the cylinder hole 41 of the protective cylinder 4, creating a gap between the pressure spring 3 and the cylinder hole 41. The bottom end 31 includes a mounting end 33. This gives the cylinder hole 41 a bottom 43, and the mounting end 33 of the pressure spring 3 abuts against the bottom 43. For example, the pressure spring 3 can be directly placed in the cylinder hole 41 with the mounting end 33 abutting against the bottom 43, or the mounting end 33 of the pressure spring 3 can be fixed to the bottom 43 by a fixing means.

[0058] After using this optimization method, the following can be obtained: Figure 1 The optimized inlet nozzle adjustment mechanism 10 shown is constructed as follows.

[0059] In this optimization method, the protective cylinder 4 can have a protruding section 48 that protrudes beyond the disk surface 28 of the support disk 2, with the disk surface 28 of the support disk 2 facing the nozzle cover ring 1. The distance s1 between the end face 49 of the protruding section 48 and the annular surface 18 of the nozzle cover ring 1 can also be 1~5mm, wherein the annular surface 18 of the nozzle cover ring 1 faces the protruding section 48. Furthermore, the gap g3 between the pressure spring 3 and the cylinder hole 41 can be 1~3mm at any point.

[0060] In this optimization method, the protective cylinder 4 can have a threaded rod segment 47 with external threads, so that the protective cylinder 4 is threadedly connected to the threaded hole segment 22 of the mounting hole 21 through the threaded rod segment 47 and thus adapted to the mounting hole 21.

[0061] The term "and / or" as used herein includes any and all combinations of one or more of the related listed items. Unless otherwise stated, all terms used herein (including technical and scientific terms) have the same meaning as commonly understood in the art to which this invention pertains. It should also be understood that terms, such as those defined in common dictionaries, should be understood to have the same meaning as they have in the context of this specification and the related art, and should not be interpreted in an idealized or overly formal sense unless expressly stated herein. For the sake of brevity and / or clarity, well-known functions or constructions may not be described in detail.

[0062] Unless otherwise clearly indicated, each aspect or embodiment defined herein may be combined with any other aspect or embodiment. In particular, any feature indicated as preferred or advantageous may be combined with any other feature indicated as preferred or advantageous.

[0063] The embodiments described in this specification are merely preferred embodiments of the present invention. These embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit the scope of the present invention. All technical solutions that can be obtained by those skilled in the art based on the concept of the present invention through logical analysis, reasoning, or limited experimentation should be within the scope of the present invention.

Claims

1. An inlet nozzle adjusting mechanism for a turbine expander, comprising a nozzle cover ring, a support plate, and a pressure spring, wherein the mounting end of the pressure spring is installed in a mounting hole of the support plate, and the telescopic end of the pressure spring is connected to the nozzle cover ring, characterized in that, The inlet nozzle adjustment mechanism further includes a protective cylinder, which is installed in the mounting hole of the support plate. The bottom end of the pressure spring is accommodated in the cylinder hole of the protective cylinder, and there is a gap between the pressure spring and the cylinder hole. The bottom end includes the mounting end. The cylinder hole has a bottom, and the mounting end of the pressure spring abuts against the bottom of the hole.

2. The inlet nozzle adjusting mechanism as described in claim 1, characterized in that, The protective cylinder has a protruding section that extends beyond the surface of the support disk, the surface of the support disk facing the nozzle cover ring.

3. The inlet nozzle adjusting mechanism as described in claim 2, characterized in that, There is a gap between the end face of the protruding cylindrical section and the annular surface of the nozzle cover ring, wherein the annular surface of the nozzle cover ring faces the protruding cylindrical section, and the gap is 1~5mm; and / or The pressure spring is arranged such that the gap between the pressure spring and the cylinder hole is 1~3mm at any point.

4. The inlet nozzle adjusting mechanism as described in claim 1, characterized in that, The protective cylinder has a threaded rod section with external threads, and the protective cylinder is adapted to the mounting hole by being threadedly connected to the threaded hole section of the mounting hole through the threaded rod section.

5. The inlet nozzle adjusting mechanism as described in claim 4, characterized in that, The mounting hole is a stepped hole; The small-diameter section of the stepped hole constitutes the threaded section, which is threadedly connected to the threaded rod section with a smaller outer diameter of the protective cylinder, while the large-diameter section of the stepped hole is a smooth hole, which is adapted to the smooth rod section with a larger outer diameter of the protective cylinder.

6. The inlet nozzle adjusting mechanism as described in claim 5, characterized in that, The protective cylinder has a through hole that is disposed in the smooth rod section of the protective cylinder, and the protective cylinder also has a through hole in the threaded rod section; The smaller-diameter perforation is connected to the larger-diameter cylindrical hole, thereby forming a stepped hole, and the stepped surface of the stepped hole constitutes the bottom of the cylindrical hole.

7. A spring mounting structure for fluid machinery, comprising a movable seat, a base, and a pressure spring, wherein fluid flows around the pressure spring, a mounting end of the pressure spring is mounted in a mounting hole in the base, and a telescopic end of the pressure spring is connected to the movable seat, characterized in that, The spring mounting structure further includes a protective cylinder, which is installed in the mounting hole of the base. The bottom end of the pressure spring is accommodated in the cylinder hole of the protective cylinder, and there is a gap between the pressure spring and the cylinder hole. The bottom end includes the mounting end. The cylinder hole has a bottom, and the mounting end of the pressure spring abuts against the bottom of the hole.

8. The spring mounting structure as described in claim 7, characterized in that, The protective cylinder has a protruding section that extends beyond the surface of the base, and the surface of the base faces the movable seat; There is a gap of 1-5 mm between the end face of the protruding cylindrical section and the surface of the movable seat, wherein the surface of the movable seat faces the protruding cylindrical section; and / or The pressure spring is arranged such that the gap between the pressure spring and the cylinder hole is 1~3mm at any point.

9. The spring mounting structure as described in claim 7, characterized in that, The protective cylinder has a smooth rod section with a large outer diameter and a threaded rod section with a small outer diameter and external threads; The mounting hole is a stepped hole, which includes a small-diameter hole section with internal threads and a large-diameter hole section in the form of a smooth hole. The threaded section of the protective cylinder is threadedly connected to the small-diameter hole section of the mounting hole, and the smooth section of the protective cylinder is adapted to the large-diameter hole section of the mounting hole.

10. The spring mounting structure as described in claim 9, characterized in that, The protective cylinder has a through hole that is disposed in the smooth rod section of the protective cylinder, and the protective cylinder also has a through hole in the threaded rod section; The smaller-diameter perforation is connected to the larger-diameter cylindrical hole, thereby forming a stepped hole, and the stepped surface of the stepped hole constitutes the bottom of the cylindrical hole.

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